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Inventors
Leonard, Willie B.
Application #
027668
Filed
Apr-6-1979
Published
Sep-20-1983
Current US Class
091/374
091/444
091/461
091/48
091/506
091/51
International Classes
F01B 003/00; F15B 009/10
Field of Search
91/51 91/506 91/448 91/402
Examiners
Maslousky; Paul E.
Attorney, Agent or Firm
Robinson; Murray, Conley; Ned L., Rose; David Alan
Referenced by:
View Backward References
Citation
Cite This Patent
More From Subclass 461
More From Class 091
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Abstract
Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor means cooperating with vent openings to vary venting and thereby vary fluid pressures in the fluid passages. Fluid conduits connect these pressure outputs to a double acting piston moving in a cylinder whose opposite ends are connected to the fluid conduits. The piston and cylinder form the responder of the system. A receiver is formed by a piston and cylinder or other fluidic motor remotely fluidically connected to the responder, the motor driving a load. A feedback means controlled by the position of the responder piston and/or the load varies pressure in the fluid conduits by variably venting same. Both rotary and linear types of transmitters and load feedback means and receivers may be used. The transmitter may vary the pressure in each of two lines, but directly varying the pressure in only one line at a time, and may be operated by a single control or by two controls, each varying the pressure in one line, or by one control varying the restriction and the other selecting the line, and may be used to operate a swash plate pump/motor load, with pressure override and emergency stop controls. The responder may form an annular space between each piston land and either side of a cylinder flange.
Claims
I claim:
1. A fluidic repeater system comprising:
a source of fluid under pressure;
a first and a second fluid restrictor;
a first fluid passage connected to said source through said first fluid restrictor;
a second fluid passage connected to said source through said second fluid restrictor;
a reservoir of fluid having a pressure less than that of the fluid of said source;
transmitter means for variably venting both said first and said second passages to said reservoir in such a manner that one of said fluid passages can be variably vented by said transmitter means while the other of said fluid passages is not vented by said transmitter means;
said transmitter means being positionable, while the second passage is not vented, in a first stationary position of low venting of the first passage and a second stationary position of increased venting of the first passage and a plurality of stationary positions between said first and second stationary positions in which said first passage is vented differing amounts;
said transmitter means being positionable, while the first passage is not vented, in a third stationary position of low venting of the second passage and a fourth stationary position of incresed venting of the second passage and a plurality of stationary positions between said third and fourth stationary positions in which said second passage is vented differing amounts; and
first responder means including a first piston in a cylinder for providing mechanical displacement of said first piston with respect to said cylinder in response to change in the differential of the pressure of the fluid in said first passage and the pressure of the fluid in said second fluid passage,
said transmitter means in each of said stationary positions venting the respective passage an amount which is invariant with respect to changes in the relative positions of the responder piston and cylinder.
2. A fluidic repeater system as recited in claim 1 further comprising:
a first load wherein said first load includes a servo means positioned swash plate of a swash plate pump unit and a load control valve means connected to said responder means for controlling supply of fluid to said servo means.
3. A fluidic repeater system as recited in claim 2 wherein:
said load control valve means is mechanically linked to said responder piston.
4. A fluidic repeater system as recited in claim 1 wherein:
said responder cylinder has a reduced diameter portion, a first normal diameter portion on one side of said reduced diameter portion, and a second normal diameter portion on the other side of said reduced diameter portion, first flow path means at all times communicating said first fluid passage with a single one of said normal diameter portions and second flow path means at all times communicating said second fluid passage with the other single one of said normal diameter portions, and
said responder means piston including a responder piston shaft disposed in said reduced diameter portion of said first responder means cylinder and extending at either end into said normal diameter portions and having responder piston bearing lands at either end of said responder piston shaft, said bearing lands slidingly and sealingly engaging said normal diameter portions of said responder cylinder.
5. A fluidic repeater system as recited in claim 4 wherein:
the cylindrical surface of said reduced diameter portion of said responder clylinder has an outlet port at its axial center and a radial passageway connecting said outlet port to said reservoir, and said responder means includes axial variable depth grooves in said responder piston for variably venting the fluid at either side of said reduced diameter portion of said responder piston for variably venting the fluid at either side of said reduced diameter portion of said responder means cylinder to said reservoir in accordance with the position of the responder piston.
6. A fluidic repeater system as recited in claim 5 wherein:
said radial passageway includes a variable restrictor means for variably restricting fluid flow through said radial passageway.
7. A fluidic repeater system as recited in claim 1 further comprising a first load wherein said first load includes a servo means positioned swash plate of a swash plate pump unit and a swash plate pump load control valve means connected to said responder means controlling supply of fluid to said servo means.
8. A fluidic repeater system as recited in claim 7 wherein:
said swash plate pump load control valve means is mechanically linked to said first responder piston.
9. A fluidic repeater system comprising
a source of fluid under pressure;
a first and a second fluid restrictor;
a first fluid passage connected to said source through said first fluid restrictor;
a second fluid passage connected to said source through said second fluid restrictor;
a reservoir of fluid having a pressure less than that of the fluid of said source;
transmitter means for variably venting both said first and second passages to said reservoir in such a manner that one of said fluid passages can be variably vented by said transmitter means while the other of said fluid passages is not vented by said transmitter means;
said transmitter means being positionable, while the second passage is not vented, in a first stationary position of low venting of the first passage and a second stationary position of increased venting of the first passage and a plurality of stationary positions between said first and second stationary positions in which said first passage is vented differing amounts;
said transmitter means being positionable, while the first passage is not vented, in a third stationary position of low venting of the second passage and a fourth stationary position of increased venting of the second passage and a plurality of stationary positions between said third and fourth stationary positions in which said second passage is vented differing amounts; and
first responder means including a first piston in a responder cylinder for providing mechanical displacement of said first piston with respect to said responder cylinder in response to change in the differential to the pressure of the fluid in said first fluid passage and the pressure of the fluid in said second fluid passage,
said transmitter means including valve means controlling fluid flow between port means connected respectively to said passage means and said reservoir, said port means having positions fixed independent of the position of said responder means,
said first responder means including first feedback means for simultaneously variably venting both of said fluid passages to said reservoir through path means different from the vent path through which said transmitter means vents said first and second passages to said reservoir, the extent of venting of a particular fluid passage by said first feedback means being dependent on the position of said first piston with respect to said responder cylinder, being independent of the rate at which said first piston is changing position, and being such that a pressure differential between the fluid within said first fluid passage and the fluid within the second fluid passage causing displacement of said first piston is negated by said first feedback means when the first piston reaches a certain position to cause said first piston to come to rest in said certain position, said first piston having a different position of rest corresponding to each position of said pluralities of positions of said transmitter means.
10. A fluidic repeater system as recited in claim 9 wherein said transmitter means includes:
an inlet conduit,
second valve means for switchably connecting said first and second fluid passages to said inlet conduit such that only one fluid passage is in communication with said inlet conduit at any given time, and
said transmitter means variably venting fluid within said inlet conduit to said reservoir.
11. A fluidic repeater system as recited in claim 10 wherein:
said valve means is a three-way, two-position fluidic valve.
12. A fluidic repeater system as recited in claim 10 wherein:
said transmitter venting means includes an outlet connected to said inlet conduit and an obstructor means for variably obstructing fluid flow from said outlet to said reservoir.
13. A fluidic repeater system as recited in claim 12 wherein:
said transmitter means further includes a cylinder in communication with said reservoir, said outlet being a sideport in said cylinder and said obstructor means being a partially cylindrical, rotatable land disposed within said cylinder, a portion of said land being undercut below full diameter.
14. A fluidic repeater system as recited in claim 13 wherein:
said undercut portion is of variable depth of undercut.
15. A fluidic repeater system as recited in claim 14 wherein:
said undercut tapers from the ends of the undercut toward the middle of the undercut.
16. A fluidic repeater system as recited in claim 13 wherein:
said undercut portion extends over an area of approximately 85 degrees of the surface of said land.
17. A fluidic repeater system as recited in claim 13 wherein:
said land is biased to a position wherein said nozzle is competely obstructed by said land.
18. A fluidic repeater system is recited in claim 9 further comprising:
a first load wherein said first load includes a servo means positioned swash plate of a swash plate pump unit and a swash plate pump load control valve means connected to said responder means for controlling supply of fluid to said servo means.
19. A fluidic repeater system, as recited in claim 18 wherein:
said swash plate pump load control valve is mechanically linked to said first responder piston.
20. A fluidic repeater system as recited in claim 19 wherein:
said swash plate pump load control valve includes a piston axially movably disposed in an extension of said responder cylinder.
21. A fluidic repeater system as recited in claim 18 wherein:
said first load includes pressure over-ride control means for limiting the amount said swash plate can move from the vertical.
22. A fluidic repeater system as recited in claim 18 wherein:
said first load includes emergency stop means for returning said swash plate toward the vertical.
23. A fluidic repeater system as recited in claim 22 wherein:
said swash plate pump load control valve has a pressure fluid input and said emergency stop means includes a stop means valve for selectively connecting said pressure fluid input to a source of pressure fluid and to said reservoir.
24. A fluidic repeater system as recited in claim 23 wherein:
said stop means valve is biased such that said pressure fluid input of said swash plate pump controller is normally connected to a source of pressure fluid.
25. A fluidic repeater system as recited in claim 9 wherein:
said first responder means further includes:
a cylinder having an annular flange therein, said annular flange having an internal cylindrical surface;
an outlet conduit connecting the axial center of said cylindrical surface of said annular flange to said reservoir;
a first inlet port on one side of said flange connected to said first fluid passage;
a second inlet port on the other side of said flange connected to said second fluid passage;
a piston spool having a generally cylindrical shaft slidingly disposed within said cylindrical surface of said flange and two cylindrical lands at either end of said shaft, said cylindrical lands slidingly engaging the wall of said cylinder.
26. A fluidic repeater as recited in claim 25 wherein:
said first feedback means includes variable depth grooves in said shaft of said piston spool, said grooves being deepest at the axial center of said shaft and being symmetrical about the center of said shaft.
27. A fluidic repeater system as recited in claim 26 wherein:
said cylindrical surface of said flange is recessed over most of its length forming a groove with ridges at either end.
28. A fluidic repeater system as recited in claim 27 wherein:
said piston spool is mechanically linked to control valve means for a swash plate pump unit.
29. A fluidic repeater system comprising:
first and second fluid passage means for communicating fluid under pressure;
transmitter means for varying the pressure of the fluid within said fluid passage means,
responder means for providing mechanical displacement in response to changes in the differential of the pressure of the fluid in said first passage means and the pressure of the fluid in said second passage means, said responder means including:
(a) a cylinder having a reduced diameter portion, a first normal diameter portion to one side of said reduced diameter portion and a second normal diameter portion to the other side of said reduced diameter portion, first flow path means at all times communicating said first flow passage means with a single one of said normal diameter portions at a point near the juncture of said one normal diameter portion with said reduced diameter portion, second flow path means at all times communicating said second flow passage means with the other single one of said normal diameter portions at a point near the juncture of said other normal diameter portion with said reduced diameter portion,
(b) a piston axially movably disposed in said cylinder, said piston having a piston shaft slidingly and sealingly disposed in said reduced diameter portion of said cylinder, said piston shaft having an axial length greater than that of said reduced diameter portion, and said piston having a first bearing land for slidingly engaging the wall of said first normal diameter portion and a second bearing land for slidingly and sealingly engaging the wall of said second normal diameter portion, said bearing lands being connected to either end of said piston shaft.
30. A fluidic repeater system as recited in claim 29 wherein:
the cylindrical surface of said reduced diameter portion of said responder cylinder has an annular groove centered thereon, and said responder means includes an outlet port at the axial center of said reduced diameter portion of said responder cylinder and an outlet passageway extending from said outlet port and connected to a low pressure fluid reservoir, and said piston shaft has variable depth grooves thereon for variabley venting fluid within said normal diameter portions of said responder cylinder to the reservoir through said outlet port.
31. A fluidic repeater system as recited in claim 30 wherein:
said outlet passageway includes variable restrictor means for variably restricting fluid flow through said outlet passageway.
32. A fluidic repeater system comprising:
a source of fluid under pressure;
a first and a second fluid restrictor;
a first fluid passage connected to said source through said second fluid restrictor;
a reservoir of fluid having a pressure less than that of the fluid of said source;
transmitter means for variably venting both said first and said second passages to said reservoir in such a manner that one of said fluid passages can be variably vented by said transmitter means while the other of said fluid passages is not vented by said transmitter means;
first responder means including a first piston in a cylinder for providing mechanical displacement of said first piston with respect to said cylinder in response to change in the differential of the pressure of the fluid in said first fluid passage and the pressure of the fluid in said second fluid passage,
said transmitter means including a first outlet connected to said first fluid passage, a second outlet connected to said second fluidic passage, a first obstructor means for variably obstructing fluid flow from said first outlet to said reservoir, and a second obstructor means for variably obstructing flor from said second outlet to said reservoir; each said obstructor being operable to close flow from one outlet while the other obstructor variably obstructs flow from the other outlet, the extent of obstructing of said outlets being independent of the relative positions of said piston and cylinder of said first responder means.
33. A fluidic repeater system as recited in claim 9 wherein
said first responder means includes first feedback means for simultaneously variably venting both of said fluid passages to said reservoir through path means different from the vent path through which said transmitter means vents said first and second passages to said reservoir, the extent of venting of a particular fluid passage by said first feedback means being dependent on the position of said first piston with respect to said cylinder, being independent of the rate at which said first piston is changing position, and being such that a pressure differential between the fluid within said first fluid passage and the fluid within the second fluid passage causing displacement of said first piston is negated by said first feedback means when the first piston reaches a certain position, said first piston having a different position of rest corresponding to each position of said pluralities of positions of said transmitter,
said transmitter means further including:
a first transmitter cylinder communicating with said reservoir, said first outlet being a side port in said first transmitter cylinder, said first obstructor means being a first plug rotatably mounted in said first transmitter cylinder about an axis coaxial with said cylinder and having a partially cylindrical first land, said second transmitter first land being undercut below full diameter over a first portion of its surface; and
a second transmitter cylinder communicating with said reservoir, said second outlet being a side port in said second transmitter cylinder, said second obstructor means being a second plug rotatably mounted in said second transmitter cylinder about an axis coaxial with said cylinder and having a partially cylindrical second land, said second land being undercut over a first portion of its surface.
34. A fluidic repeater as recited in claim 33 wherein:
said first transmitter cylinder and said first plug are substantially identical to said second transmitter cylinder and said second plug respectively.
35. A fluidic repeater system as recited in claim 33 wherein:
said lands are biased to a position wherein the corresponding outlet is completetly obstructed.
36. A fluidic repeater system as recited in claim 33 further comprising:
a third and a fourth fixed fluid restrictor;
a third fluid passage connected to said source through said third fluid restrictor;
a fourth fluid passage connected to said source through said fourth fluid restrictor;
a second responder means including a second piston in a cylinder for providing mechanical displacement of said second piston relative to said cylinder in response to change in the differential of the pressure of the fluid in said third fluid passage and the pressure of the fluid in said fourth fluid passage; and
second feedback means for variable venting said third and fourth fluid passages to said reservoir, the extent of venting of a particular fluid passage being dependent on the position of said second piston relative to said second cylinder, being independent of the rate at which said second piston is changing position, and being such that a pressure differential between the fluid within said third fluid passage and the fluid within said fourth fluid passage causing displacement of the load is negated by said second feedback means when said second piston reaches a certain position;
said transmitter means further including a third outlet which is a sideport in said first transmitter cylinder, said third outlet being substantially diametrically opposed to said first outlet and connected to said third fluid passage, and a fourth outlet which is a sideport in said second transmitter cylinder, said fourth outlet being substantially diametrically opposed to said second outlet and connected to said fourth fluid passage.
37. A fluidic repeater system as recited in claim 36 further comprising:
a first load and a second load, wherein said first load includes a servo means positioned first swash plate of a first swash plate pump unit and a first swash plate pump load control valve means connected to said first responder means for controlling supply of fluid to said servo means, and said second load includes a servo means positioned second swash plate of a second swash plate pump unit and a second swash plate pump load control means connected to said second responder means for controlling supply of fluid to said servo means.
38. A fluidic repeater system as recited in claim 37 wherein:
said first swash plate pump load control valve means is mechanically linked to said first responder means piston, and said second swash plate pump load control valve means is mechanically linked to said second responder means piston.
39. A fluidic repeater system as recited in claim 32 wherein:
said first responder means includes first feedback means for variably venting at least one of said fluid passages to said reservoir through path means different from the vent path through which said transmitter means vents said first and second passages to said reservoir,
the extent of venting of a particular fluid passage by said first feedback means being dependent on the position of said first piston with respect to said cylinder, being independent of the rate at which said first piston is changing position, and being such that a pressure differential between the fluid within said first fluid passage causing displacement of said first piston is negated by said first feedback means when the first piston reaches a certain position to cause said first piston to come to rest in said certain position,
said first piston having a different position of rest corresponding to each position of said pluralities of positions of said transmitter.
40. A fluidic repeater as recited in claim 39 wherein:
said first feedback means vents the same passage as is vented by the transmitter.
41. A fluidic repeater as recited in claim 39 wherein:
when said transmitter means vents one of said fluid passages said feedback means vents another of said fluid passages.
42. A fluidic repeater as recited in claim 39 wherein:
when said transmitter means vents one of said passages said feedback means vents both of said fluid passages.
43. Fluidic repeater system comprising
a source of fluid under pressure;
a first and a second fluid restrictor;
a first fluid passage connected to said source through said first fluid restrictor;
a second fluid passage connected to said source through said second fluid restrictor;
a reservoir of fluid having a pressure less than that of the fluid of said source;
transmitter means for variably venting both said first and said second passages to said reservoir in such a manner that one of said fluid passages can be variably vented by said transitter means while the other of said fluid passages is not vented by said transmitter means;
first responder means including a first piston in a cylinder for providing mechanical displacement of said first piston with respect to said cylinder in response to change in the differential of the pressure of the fluid in said first fluid passage and the pressure of the fluid in said second fluid passage,
said transmitter means comprising:
a transmitter cylinder communicating with said reservoir;
a plug having a generally cylindrical outer periphery mounted for rotation in said cylinder about an axis coaxial with the cylinder axis of said cylinder and plug;
said outlets being substantially diametrically opposed sideports in said cylinder;
said first obstructor means being a land formed by a first half of said periphery and said second obstructor means being a land formed by the second half of said periphery, said first half being undercut below full diameter at a first undercut portion and said second half being undercut at a second undercut portion, other portions of said lands having a diameter substantially equql to the inner diameter of said transmitter cylinder,
said transmitter cylinder having an inner periphery immediately adjacent the outer periphery of said plug, except where undercut, said side ports in said transmitter cylinder opening to said inner periphery of the transmitter cylinder, said transmitter cylinder and said side ports therein being stationary and their positions remaining fixed despite movement of said piston of the responder means.
44. A fluidic repeater system comprising:
a source of fluid under pressure;
a first and a second fluid restrictor;
a first fluid passage connected to said source through said first fluid restrictor;
a second fluid passage connected to said source through said second fluid restrictor;
a reservoir of fluid having a pressure less than that of the fluid of said source;
transmitter means for variably venting both said first and second passages to said reservoir in such a manner that one of said fluid passages can be variably vented by said transmitter means while the other of said fluid passages is not vented by said transmitter means;
said transmitter means being positionable, while the second passage is not vented, in a first stationary position of low venting of the first passage and a second stationary position of increased venting of the first passage and a plurality of stationary positions between said first and second stationary positions in which said first passage is vented differing amounts;
said transmitter means being positionable, while the first passage is not vented, in a third stationary position of low venting of the second passage and a fourth stationary position of increased venting of the second passage and a plurality of stationary positions between said third and fourth stationary positions in which said second passage is vented differing amounts; and
first responder means including a first piston in a cylinder for providing mechanical displacement of said first piston with respect to said cylinder in response to change in the differential of the pressure of the fluid in said first fluid passage and the pressure of the fluid in said second fluid passage;
said transmitter means including valve means controlling fluid flow between port means connected respectively to said passage means and said reservoir, said port means having positions fixed independent of the position of said responder means,
said transmitter means including a first outlet connected to said first fluid passage, a second outlet connected to said second fluid passage, a first obstructor means for variably obstructing fluid flow from said first outlet to said reservoir, and a second obstructor means for variably obstructing flow from said second outlet to said reservoir, each said obstructor being operable to close flow from one outlet while the other obstructor variably obstructs flow from the other outlet,
said first obstructor means and said second obstructor means being connected together in such a way that at least one of said obstructor means is fully obstructing the corresponding outlet at any given time,
said transmitter means further including:
a transmitter cylinder communicating with said reservoir;
a plug having a generally cylindrical outer periphery mounted for rotation in said cylinder about an axis coaxial with the cylinder axis of said cylinder and plug;
said outlets being substantially diametrically opposed side ports in said cylinder;
said first obstructor means being a land formed by a first half of said periphery and said second obstructor means being a land formed by the second half of said periphery, said first half being undercut below full diameter at a first undercut portion and said second half being undercut at a second undercut portion, other portions of said lands having a diameter substantially equal to the inner diameter of said transmitter,
wherein one end of said cylinder is connected to said first fluid passage and the other end of said cylinder is connected to said second fluid passage,
and wherein said first responder means includes feedback means responsive to the position of the responder piston to negate pressure differential between the fluid in said first and second fluid passages caused by said transmitter,
said feedback means including cylinder grooves in the wall of said cylinder, venting conduits connecting said grooves to said reservoir and variable depth grooves in the ends of said first piston for venting variable amounts of the fluid at the ends of said cylinder to said cylinder grooves.
45. A fluidic repeater system as recited in claim 12 wherein:
said venting conduits each include a variable restrictor means for variably restricting flow through the respective conduit.
46. A fluidic repeater system
a source of fluid under pressure;
a first and a second fluid restrictor;
a first fluid passage connected to said source through said first fluid restrictor;
a second fluid passage connected to said source through said second fluid restrictor;
a reservoir of fluid having a pressure less than that of the fluid of said source;
transmitter means for variably venting both said first and second passages to said reservoir in such a manner that one of said fluid passages can be variably vented by said transmitter means while the other of said fluid passages is not vented by said transmitter means;
said transmitter means being positionable, while the second passage is not vented, in a first stationary position of low venting of the first passage and a second stationary position of increased venting of the first passage and a plurality of stationary positions between said first and second stationary positions in which said first passage is vented differing amounts;
said transmitter means being positionable, while the first passage is not vented in a third stationary position of low venting of the second passage and a fourth stationary position of increased venting of the second passage and a plurality of stationary positions between said third and fourth stationary positions in which said second passage is vented differing amounts; and
first responder means including a first piston in a cylinder for providing mechanical displacement of said first piston with respect to said cylinder in response to change in the differential of the pressure of the fluid in said first fluid passage and the pressure of the fluid in said second fluid passage,
said transmitter means including valve means controlling fluid flow between port means connected respectively to said passage means and said reservoir, said port means having positions fixed independent of the position of said responder means,
said responder cylinder having a reduced diameter portion, a first normal diameter portion on one side of said reduced diameter portion, and a second normal diameter portion on the other side of said reduced diameter portion, first flow passage means at all times communicating said first fluid passage with a single one of said normal diameter portions and second flow passage means at all times communicating said second fluid passage means at all times communicating said second fluid passage with the other of said normal diameter portions and having responder piston bearing lands at either end of said responder piston shaft, said bearing lands slidingly and sealingly engaging said normal diameter portions of said responder cylinder.
47. A fluidic repeater system as recited in claim 46 wherein the cylindrical surface of said reduced diameter portion of said responder cylinder has an outlet port at its axial center and a radial passageway connecting said outlet port to said reservoir, said responder means including feedback means which includes axial variable depth grooves in said responder piston shaft for variably venting the fluid at either side of said reduced diameter portion of said first receiver cylinder to said reservoir according to the position of said piston relative to said cylinder.
48. A fluidic repeater system as recited in claim 47 further comprising:
a first load wherein said first load includes a servo means positioned swash plate of a swash plate pump unit and a load control valve means connected to said responder means for controlling supply of fluid to said servo means.
49. A fluidic repeater system as recited in claim 48 wherein:
said load control valve is mechanically linked to said responder means piston.
50. A fluidic repeater system as recited in claim 49 wherein:
said load control valve includes a valve piston axially movably disposed in an extension of said responder means cylinder.
51. A fluidic repeater as recited in claim 47 wherein:
said reduced diameter portion of said responder cylinder is an annular member and said first and second normal diameter portions of said responder cylinder are connected by a third normal diameter portion therebetween and in which said annular member is slidingly mounted, and including adjustable means to hold said annular member in any desired axial position relative to said normal diameter portions of the cylinder.
Description
BACKGROUND OF THE INVENTION
This invention pertains to fluidic, e.g. hydraulic or pneumatic, repeaters useful as remote indicators and servo proportional controllers for either amplification or remote operation, e.g. in seismic generators, aircraft controls, boat steering, automobile wheel tracking, plow jerkers, and vibration test equipment.
Hydraulic devices employing mechano-hydraulic transmitters including an obstructor moving relative to two liquid ports connected to a liquid supply having a drooping pressure-load characteristic are known. It is also known to employ as a receiver or responder a double acting piston moving in a cylinder whose ends are connected by fluid conduits to the transmitter liquid supply upstream of the transmitter ports and to connect the piston mechanically or hydraulically to an output. Various feedbacks from the output to the transmitter are also known.
SUMMARY OF THE INVENTION
According to the invention, means for feedback control, whether incorporated directly in the double acting piston or mechanically connected thereto, comprises variable cross-section surface passages, e.g. tapered grooves. These grooves may be in the ends of a double acting piston cooperating with ports or side recesses of a cylinder. The piston moves to variably throttle fluid vented from the high pressure ends of the piston ends of the piston to lower pressure portions of the system. The invention further includes improved transmitter, responder and receiver means useful with the feedback means of the invention, e.g. systems in which the transmitter has a single line output for actuating the responder or receiver, systems in which the transmitter operates by variable throttling, and systems employing rotary type transmitters and systems with rotary type feedback means. Other features of the invention and objects and advantages thereof will appear hereinafter.
The feedback venting and the transmitter venting flow passages are in parallel so that the rate of venting effected by the feedback means is dependent solely on the position of the feedback means.
Various applications of the invention, e.g. to crane control, seismic generator drive, swash plate angle control of a swash plate controlled motor-pump unit, four wheel drive, and master and slave systems are disclosed.
Furthermore, the double-acting piston may be a spool with lands at either end and acting about an internal annular flange extending from the surface of the cylinder to the surface of the hub portion of the piston spool. High pressure fluid ports, with pressure varied by the transmitter, are connected to axially-directed ports in the annular flange such that the pressure of the fluid in the conduits is directed against the inside wall of the respective piston land. The hub portion has variable cross section grooves that communicate with lower pressure portions of the system through a passage in the annular flange of the cylinder whereby the piston moves to variably throttle the fluid moving from the high-pressure conduits to the lower pressure portions.
Additionally, the transmitter includes an improved rotary transmitter that varies the pressure of the fluid in two conduits, but varies the pressure of the fluid in only one conduit at a time. Such an improved transmitter has numerous applications and can be used to control a swash plate pump/motor unit in such a way that as the pressure of the fluid in one conduit is varied, the motor rotates at varying speeds in a clockwise direction, and as the pressure of the fluid in the other conduit is varied, the motor rotates at varying speeds in a counterclockwise direction.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more detailed description of several preferred embodiments of the invention reference will now be made to the accompanying drawings wherein:
FIG. 1 is a largely schematic sectional view illustrating a fluidic repeater according to the preferred embodiment of the invention;
FIGS. 2 and 3 are fragmentary views similar to FIG. 1 showing modifications;
FIGS. 4 and 5 are views similar to FIGS. 1-3 showing two further modifications;
FIGS. 6, 7, and 8 are elevational, sectional and end views respectively of the end of the amplifier piston of the FIG. 5 embodiment;
FIG. 9 is a view similar to FIG. 8 showing another embodiment;
FIG. 10 is a cross-sectional schematic view of a mechanical to fluidic translator according to the invention;
FIG. 11 is a sectional view of part of the spool valve shown in FIG. 10;
FIGS. 12, 13 and 14 are largely schematic sectional views showing further embodiments of the invention; and
FIGS. 15 and 16 are sectional views of feedback elements of the embodiments shown in FIGS. 12 through 14;
FIG. 17 is a largely schematic cross-sectional view illustrating a fluidic repeater according to an embodiment of the invention;
FIG. 18 is a view similar to FIG. 17 showing another embodiment;
FIG. 19 is a view similar to FIG. 18 showing an embodiment of the invention using only a single pressure line for control;
FIGS. 20 and 21 are views similar to FIG. 19 showing other embodiments of the invention using single control lines;
FIG. 22 is a sectional view of elements of the embodiments shown in FIGS. 20 and 21;
FIG. 23 is a fragmentary schematic sectional view of a portion of an embodiment of the invention;
FIG. 24 is a view similar to FIG. 23 showing a portion of another embodiment;
FIG. 25 is a fragmentary, largely schematic sectional view showing a portion of an embodiment of the invention;
FIG. 26 is a fragmentary sectional view of a commercial embodiment of the invention;
FIG. 27 is an elevational view of a section of FIG. 26 taken along lines 27--27;
FIGS. 28 and 29 are sectional views of valves used in the invention's embodiment depicted in FIG. 26;
FIG. 30 is a partially sectional view of another commercial embodiment of the invention;
FIG. 31 is a sectional view of the transmitter illustrated in FIG. 30 taken along lines 31--31.
FIG. 32 is a largely schematic sectional view illustrating another embodiment of the invention somewhat similar to the embodiment of FIG. 19;
FIG. 33 is a view similar to that of FIG. 32 showing a further modification;
FIG. 34 is a view largely in section showing a commercial embodiment and slight modification of the apparatus shown in FIG. 32;
FIG. 35 is a largely schematic sectional view illustrating a modification of the invention shown in FIG. 20;
FIG. 36 is a largely schematic view partly in section illustrating a modification of a form of the invention shown in FIG. 5;
FIG. 37 is a side elevation, largely in section, of a load cylinder with a feedback means incorporated therein in accordance with one form of the invention;
FIG. 38 is a side elevation, partly schematic, showing the invention incorporated in apparatus for loading a floating vessel by a crane located on a pier;
FIG. 39 is a largely schematic elevation, partly in section, of the hydraulic system and related parts of the apparatus shown in FIG. 38;
FIG. 40 is a sectional view of apparatus according to the invention incorporated into a system for varying the angle of a swash plate controlled motor-pump unit;
FIG. 41 is a view similar to FIG. 40 showing a modification;
FIG. 42 is an elevation, partly in section, showing apparatus incorporating the invention forming part of a seismic generator;
FIG. 43 is a schematic plan view of apparatus according to the invention employed for driving a four wheel drive vehicle;
FIG. 44 is a largely sectional view of apparatus according to the invention suitable for dual parallel, control, e.g. as in FIG. 43;
FIG. 45 is a largely sectional view of apparatus according to the invention for dual control of the master and slave type;
FIG. 46 is a partly sectional view illustrating another form of apparatus according to the invention;
FIG. 47 is a sectional view of an amplifier forming part of a system according to the invention;
FIG. 48 is a sectional view showing a modification of the amplifier of FIG. 47;
FIG. 49 is an elevation showing a dual rotary transmitter in accordance with the invention;
FIGS. 50, 51 are sections taken on planes 50--50 and 51--51 of FIG. 49;
FIG. 52 is a largely schematic view illustrating a rotary transmitter for venting a two-line system one line at a time with a single control lever;
FIG. 52A is a sectional view of the transmitter of FIG. 52 taken along lines 52A and connected to a responder;
FIG. 53 is a largely schematic sectional view illustrating a rotary transmitter for venting a two-line system one line at a time with a single control lever and a switching valve and a modified responder piston and cylinder;
FIG. 53A is a sectional view of an alternative embodiment of the responder of FIG. 53;
FIG. 53B is an end view of the cam pin of FIG. 53A;
FIGS. 53C is a view similar to FIG. 53 but incorporating the transmitter of FIGS. 52 and 52A and the first stage responder unit of FIGS. 53A and 53B in place of those of FIG. 53.
FIG. 54 is a largely schematic sectional view illustrating a rotary transmitter for venting two-line systems, each system vented one line at a time by two control levers, and switching a modified responder piston and cylinder; like that of FIG. 53 and
FIG. 55 is a schematic plan view of a four-wheel vehicle wherein the wheels may be selectively driven individually or in unison.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to FIG. 1, a fluidic repeater comprises a pump or source (not shown) of fluid under pressure connected to conduits marked P and a sump or low pressure fluid reservoir (not shown) connected to conduits marked R. Usually the system will be hydraulic and use a liquid, e.g. mineral oil, as working fluid, but the following description refers to all embodiments of the invention and is also applicable to pneumatic systems wherein a gas, e.g. air, is the system fluid.
Fluid from pressure source conduit 11 flows through passages 13, 15 in transmitter body 17, through restrictions or orifices 19, 21 to passages 23, 25, and thence out through ports 27, 29. The ports empty into the interior of cylinder 31 formed in transmitter body 17. Cylinder 31 is vented to reservoir 51 by three ports 33, 35, and 37. A four landed spool 39 is moved axially back and forth in cylinder 31 by electromagnetic solenoid 41, which may also be a short stroke torque motor. The solenoid is biased to its midposition, as shown, by springs 40 and 42. When spool 39 is biased to mid position, as shown in FIG. 1, lands 43 and 45 fully or substantially block ports 27 and 29. This reduces the transmitter's idle power requirements. In a modulating system both ports will be partially open in the mid-position of the spool.
Operationally, electric signals applied to solenoid or electric motor 41 move spool 39 toward one end of cylinder 31. This opens either port 27 or 29 an amount whose magnitude is dependent upon the spool's movement. In a modulating system, the port not opened will be closed an amount also dependent upon the spool's axial movement. If one port is opened, e.g. port 27, pressure in passage 23 drops due to the increased fluid flow from the source through the flow restrictor or orifice 19, while closure of the other port, e.g. port 29, will cause a pressure rise in passage 25 due to the reduced flow through orifice 21. Flow passage 13 with orifice 19 and the flow passage 15 with orifice 21 thus provide fluid supplies of drooping pressure-load characteristics. Connected to this supply are ports 27, 29, and spool 39 with lands 43, 45. These provide a variable obstructor for opening and closing the ports thus variably venting the fluid supplies to provide variable pressure outputs that vary in accordance with the obstructor's position. Since obstructor position is controlled by an electric motor, the system thus far detailed provides an electrofluidic transducer transmitter.
To prevent hydraulic locking of spool 39 because of the inherent slight leakage past lands 43, and 45, the spools are relieved by providing annular spaces 47 and 49 beyond lands 43 and 45 that communicate with ports 33 and 37. These ports lead to conduit 51 that is connected to the reservoir. Spool 39 is provided with additional guidance by providing it with end lands 53 and 55. The ends of cylinder 31 are connected by fluid passage 57 that leads to chamber 58. Chamber 58 contains motor 51 and is vented to the atmosphere by passage 59.
The transmitter's varying fluid pressure outputs are conducted by fluid passages 61 and 63 to a responder, which is in this case an amplifier, comprising cylinder 65 formed in transmitter body 17. A double acting free piston 101 floats in cylinder 65, being free to move axially in response to pressure differentials at its ends. Fluid passages 61 and 63 from the transmitter are connected to the ends of cylinder 65 so their pressures can act on the free piston's ends. The outer periphery of the piston is relieved by annular grooves 73 and 75, leaving lands 77 and 79 at the ends of the piston. Annular spaces 81 and 83 formed by grooves 73 and 75 are vented to the reservoir by fluid passages 85, 87. Lands 77 and 79 are provided with sloping grooves 89 and 91, respectively, whose depth decreases progressing from the ends of the piston toward grooves 73 and 75. Sloping grooves 89 and 91 vent pressure fluid from passages 61 and 63 past lands 77 and 79 to recesses 93 and 95 in the cylinders' sides and hence to the reservoir through passages 85 and 87. Suitable means, not shown, such as a key and slot, are provided to maintain grooves 89 and 91 in azimuthal alignment with recesses 93 and 95. The size of vent openings 97 and 99 connecting grooves 89 and 91 with recesses 93 and 95 increase and decrease when piston 67 is moved axially. This venting causes negative feedback to fluid passages 61 and 63. Higher pressure at one of passage 61 or 63 than at the other moves free piston 101 in the correct direction to increasingly vent this higher pressure to a reservoir through either groove 89 or 91. Relatively lower pressure in passage 61 or 63 than in the other moves free piston 101 in a direction to reduce venting of such lower pressure to the reservoir. Due to this variable negative feedback, piston 67 moves proportionally in response to the degree of movement of spool 39 and then comes to rest.
Free piston 101 could be connected mechanically to a suitable output such as an indicator, valve or other load. Cylinder 65 and piston 101 would then constitute parts of a receiver connected to the previously described transmitter. Passages 61 and 63 could be replaced by hoses, pipes, or other extended fluid conduits. The system would then constitute a remote indicating or proportional control system.
As shown in FIG. 1, however, piston 101 and cylinder 65 form parts of a fluidic amplifier. Piston 101 is relieved at its mid portion by annular groove 67. Annular space 103 formed by groove 67 is connected by fluid passage 105 leading to a source of fluid pressure. Lands 107 and 108 between groove 67 and grooves 73 and 75, cover outlet ports 109 and 110 in cylinder 65 when piston 101 is in mid position, as shown. When piston 101 moves axially toward one end of cylinder 65 in response to electric signals supplied to conductors 111 of motor 41, then output ports 110 and 109 are uncovered in proportion to the piston's movement. One fluid of the conduits (hoses) 113 or 115 is thus connected to a source of pressure fluid through space 103 and passage 105 while the other of the conduits is connected to reservoir through either space 81 and passage 85 or space 83 and passage 87. Hoses 113 and 115 are connected to opposite ends of load cylinder 117, which, together with piston 119 therein, forms a remote receiver.
When hose 113 or 115 is connected to the source of pressure fluid and the other to the reservoir, piston 119 moves in the direction of the flow from high pressure to low pressure. Piston rods 121, 123 extend through opposite ends of the cylinder 117, leaving equal areas of piston 119 exposed to pressures in cylinder 117. Piston rod 123 is extended to connect to a mechanical load, e.g. a valve, not shown.
Piston rod 123 is also connected mechanically by bar 125 to stem 127 of feedback valve 128. For easier viewing, valve 128 is drawn to a larger scale than load cylinder 117, but it is to be understood that the areas exposed to fluid pressure in the feedback valve are negligibly small compared to those of load cylinder 117.
Stem 127 extends through sealed opening 129 into cylinder cavity 131 of valve body 163 and connects to cylindrical valve closure 133. Closure 133 is provided with two sloping grooves 135 and 137 of increasing depth progressing axially from the ends toward the midportion of the closure. The deepest portions of the grooves being continued axially at constant depth for a certain extent as shown at 139 and 141. When the closure 133 is in midposition, as shown in FIG. 1, sloping portions of grooves 135 and 137 are in register axially with annular recesses 143 and 145 in the sides of cylindrical cavity 131. Recesses 143 and 145 communicate with ports 147 and 149, respectively, which, in turn, are connected to fluid conduits (hoses) 151 and 153. Conduits 151 and 153 are connected to ports 155 and 157, respectively, leading to the ends of amplifier cylinder 65.
The ends of cylindrical valve body cavity 131 are enlarged at 159 and 161 providing annular spaces communicating both with grooves 135 and 137 and also with passages 163 and 165 leading to conduit 167 connecting with the reservoir. When closure 133 moves axially, openings 169 and 171 between grooves 135 and 137 and the sides of cylindrical valve body cavity 131 are opened or closed in proportion to the degree of axial movement. This increases the venting to the reservoir of one of the feedback conduits 151, 153 and decreasing the venting of the other.
Operationally, when a pressure differential across the ends of amplifier piston 101 causes the piston to move right or left, then load piston 119 moves in the opposite direction carrying with it attached feedback valve closure 133. This creates a pressure differential between conduits 151 and 153 opposite to that across piston 101. The feedback from valve 128 is therefore negative and tends to cancel out the pressure differential caused by movement of spool 39. This cancellation causes piston 101 to return to neutral or midposition. This discontinues the pressure differential across load piston 119, which then comes to rest in a displaced position proportional to the displacement of spool 39 that in turn was proportional to the signal strength applied to motor 41 at input 111.
Although motions of the various parts; e.g. transmitter spool 39, amplifier piston 101, load piston 119, and feedback valve closure 133; have been said to be proportional to the signal applied to the input 111 of motor 41, this is to be understood to mean only that there is a direct function between signal amplitudes and mechanical positions with an increase in signal strength causing an increase in mechanical travel. However, by appropriately shaping grooves 89, 91, 135 and 137, the proportionality may be made to approach closely a linear function. Other groove shapes than the simple sloping grooves 89, 91, 135 and 137 may be employed.
Referring now to FIGS. 2 and 3 there are shown modifications of the FIG. 1 construction. FIGS. 2 and 3 show only a portion of the apparatus shown in FIG. 1; the remainder of the FIGS. 2 and 3 apparatus being the same as that of FIG. 1. Parts that are the same as those in FIG. 1 are given like reference numbers and their description will not be repeated. An examination of FIGS. 1 and 3 will reveal that in FIG. 1 lands 43 and 45 are disposed so as to substantially block ports 27 and 29 when spool 39 is in midposition; whereas in FIG. 3 lands 43 and 45 are disposed to leave both ports 27 and 29 partly open when spool 39 is in midposition. In other respects FIGS. 1 and 3 are the same.
FIGS. 2 and 3 differ from the FIG. 1 construction in two additional respects. First, guide lands 53 and 55 are omitted from spool 39, as are leakage return ports 33 and 37 and atmosphere vent passages 57 and 59. These of course can be used wherever it is found necessary or desirable. Secondly, and most important, in FIGS. 2 and 3 separate feedback valve 128 is omitted. Instead feedback valve means comprising grooves 135 and 137 controlling fluid conduits 151 and, respectively, 153 are provided directly on the ends of piston rods 121 and 123.
Referring now to FIG. 4 there is shown another modification of the FIG. 1 system. Again like parts are given like reference numbers and will not again be described.
The primary difference between the embodiments of the invention shown in FIGS. 1 and 4 is that in FIG. 4 the spool controlled ports 27 and 29 of FIG. 1 are replaced by nozzles 27A and 29A whose flow is controlled by obstructor 39A. The latter is a hand operated wheel, as distinguished from the electric motor actuated spool 39 of FIG. 1. Bearing 201 at one side of cylindrical obstructor 39A is internally threaded to receive threaded pin 203 on which the obstructor pivots. As the obstructor is rotated it moves axially approaching one or the other of nozzles 27A or 29A and moving farther away from the nozzle not approached. By this means the fluid pressure in conduits 23 and 25 is varied. Obstructor 39A is provided with unthreaded pivot pin 205 received in bearing 206 in obstructor support body 209. Nozzles 27A and 27B discharge into the interior of body 209. Radial passages 211 and 213 in pins 203 and 205, respectively communicate with the interior of body 209 and connect with axial fluid passage 207 which discharges into return line 35 leading to the fluid reservoir.
Another difference between the construction of FIGS. 1 and 4 lies in the construction of the feedback valve 128A that is mechanically linked to load piston rod 123.
Feedback valve 128A variably vents fluid passages 61 and 63 via grooves 135 and 137, which, in this case, are connected together to form one long groove. Venting through grooves 135 and 137 can also be outwardly into the spaces 220 inside annular sealing boots 221 and thence through groove 222 back to the reservoir. When feedback valve 128A has moved far enough to equalize the pressure in fluid passages 61 and 63, piston 101 moves back to neutral position. Load piston 119 remains in its new position as controlled by the setting of manual obstructor 39A.
Another difference between the embodiments of FIGS. 1 and 4 lies in the fact that in the FIG. 4 construction the amplifier piston 101 is not provided with feedback grooves in its ends like the grooves 89 and 91 of the FIG. 1 embodiment.
Referring now to FIG. 5 there is shown a further embodiment similar to the embodiments of FIGS. 1-4 wherein like reference numbers refer to like parts that will not be redescribed. As in the FIG. 4 construction, the FIG. 5 embodiment includes a manually actuated hand wheel type obstructor 39A cooperating with nozzles 27A and 29A, rather than an electric motor actuated spool 39 cooperating with ports 27 and 29 as in FIGS. 1-3. However, as in FIGS. 1-3, the amplifier piston is provided with feedback means. In the FIG. 5 construction instead of providing the ends of amplifier piston 101 with sloping grooves as at 89, 91 extending all the way to the outer ends of the piston as in FIGS. 1-3, the sloping grooves 89A and 91A of the FIG. 5 construction terminate where they run into and communicate with annular grooves 89B and 91B around the lands 77 and 79 respectively. Grooves 89B and 91B in turn communicate with the piston's ends via radial and axial flow passages 89C, 89D and 91C, 91D. Shape of grooves 89A and 91A is shown more clearly in larger scale detail views of FIGS. 6, 7 and 8. Short grooves 89A and 91A cooperate with annular grooves 89B and 91B to provide non-linear feedback correlative to the nonlinear input of nozzle obstructor 39A. This effects a more nearly linear proportionality between hand wheel movement and amplifier piston movement.
FIG. 9 shows feedback groove 91E of rectangular cross section as an alternative to the V-shape cross section of groove 91A of FIG. 8.
No load cylinder and piston are shown in the FIG. 5 construction, but it is to be understood that amplifier output passages 113 and 115 connect via passages 117A and 117B leading to a suitable load cylinder which usually will be provided with further feedback means as in FIGS. 1-4. Without a load feedback the load piston will ultimately move to the limit of its travel regardless of the magnitude of the input at obstructor 39. The rate of this movement of the load piston will vary in proportion to the magnitude of the input at obstructor 39A. In some applications the load feedback means of the FIGS. 1-4 embodiments could also be omitted.
FIG. 5 illustrates the use of a filter screen 225 between conduit 11 leading to the source of pressure fluid and the orifices 19 and 21. This is desirable to prevent blockage of the orifice by foreign matter. This constructional detail, though not shown in FIGS. 1-4, is to be understood as being applicable to all embodiments of the invention.
FIG. 10 shows an embodiment of the invention that is much the same as that of FIG. 5. Differences include modification of the feedback groove system in the amplifier piston and the use of an electric "flapper" in place of hand wheel obstructor 39A. Like parts are given like reference numbers and their description will not be repeated.
The amplifier piston feedback groove system in FIG. 10 is similar to the system illustrated by FIG. 5 except short sloping grooves 89A and 91A are omitted. An initial axial motion of the piston 101 sufficient to communicate annular groove 89B or 91B with vent passage 85 or 87 is required before any feedback will occur. Thereafter, further movement of the piston 101 in the same direction will cause increasing venting.
If desired, lands 77 and 79 can be inwardly flaring or tapered, e.g. conically or in other manner annularly relieved between annular grooves 73 and 89B along one end and between annular grooves 75 and 91B at the other end, as shown in FIG. 11. This will effect a result similar to that attained by the embodiment illustrated in FIG. 5. The outermost parts of the lands will by cylindrical, for guide purposes, as shown at 79B.
Electric flapper 41A shown in FIG. 10 driving flapper type obstructor 39B includes horseshoe magnets 231 and 233 disposed opposite pole to opposite pole with flapper 39B pivoted therebetween at 235. Tension springs 237 and 239 connected to one end of the flapper and to motor housing 241 and adjustment screw 243 normally center the other end of the flapper between nozzles 27A and 29A. When an electric signal is applied to either input 111A or 111B of solenoid 41A or 41B the flapper is magnetized a proportional amount. This moves it toward or away from nozzle 27A or 29A. This variably vents passages 23 and 25. Fluid leaving nozzles 27A and 29A returns to the fluid reservoir through passages 35A and 35B.
FIGS. 12-14 show rudimentary fluidic repeater apparatus according to an embodiment of the invention in which transmitter obstructor 39C or 39D is of the needle valve type rather than the spool valve type shown in FIGS. 1-3 or the jet interference types shown in FIGS. 4, 5, and 10. In FIG. 12 obstructor 39C is a cylindrical plug axially movable relative to cylindrical ports 27B and 29B. Plug 39C is provided with sloping grooves 251 and 253 similar to grooves 89 and 91 of the amplifier piston of FIG. 1. According to the axial position of plug 39C more or less fluid is vented from fluid source passages 23 and 25 to chamber 255 and then through passage 35 to reservoir return conduit 51. No means for moving plug 39C is shown, but it is to be understood that any suitable means can be used, e.g. any of the manual or motor means used in the previously described embodiments.
The transmitter obstructor shown in FIG. 13 is the same as that in FIG. 12. The transmitter obstructor shown in FIG. 14 is the same as in FIGS. 12 and 13 except that the ends of the obstructor plug 39D are provided with spiral helical grooves 251A, 253A spiraling inward and progressing axially towards the plug ends, rather than the sloping grooves 251, 253 of the embodiments of FIGS. 12 and 13. The two groove constructions are further illustrated in FIGS. 15 and 16.
Referring once more to FIG. 12, receiver piston 101C is provided with sloping feedback grooves 89 and 91 similar to those shown in the embodiments of FIGS. 1-3 whereby axial motion of piston 101C due to difference in pressure between fluid passages 61 and 63 causes such venting through chamber 255 and passage 35 to reservoir return conduit 51 as to eliminate the pressure differential. The receiver piston constructions of FIGS. 13 and 14 are the same as that of FIG. 12 except that instead of sloping grooves 89 and 91 of configuration like transmitter grooves 251 and 253, the receiver pistons of FIGS. 13 and 14 are provided with spiral helical grooves of configuration similar to the grooves 251A and 253A.
No amplification is effected between transmitter plugs 39C and 39D and receiver pistons 101C and 101D. No load is shown connected to pistons 101C or 101D, but it is to be understood that they can be connected fluidically to load cylinders and pistons as are the amplifier pistons in the other embodiments, or mechanically, the same as feedback piston 133 in FIG. 1, for example, or pistons 101C and 101D could be connected to indicator or display means of minimum load power requirements.
The various vent groove configurations described herein as applicable to the transmitter plug (FIGS. 15 and 16), the amplifier or receiver piston (FIGS. 1-3, 5-14) and the load feedback piston (FIGS. 1-4) may be interchanged between the various embodiments described hereinabove or hereinafter, as may be desired or required for any reason, for example to correlate the transmitter obstructor position-vent function, the amplifier piston position-vent function, and the load feedback valve position-vent fuction.
Comparing the several embodiments of the invention thus far described it will be seen that operationally in each case a transmitter obstructor moves relative to a pair of openings. These may be side ports in a spool valve as in FIG. 1, jet nozzles as in FIGS. 4 and 10, or needle valve ports as in FIGS. 12-14. In each case a pair of openings open to some form of chamber means, e.g. a cylinder (FIG. 1), cylindrical spaces in a hand wheel block (FIG. 4), a chamber in the transmitter block (FIG. 10), or a cylindrical chamber (FIGS. 12-14). In each case flow from the pair of openings is controlled by some form of barrier means, e.g. piston lands (FIG. 1), hand wheel obstructor (FIG. 4), flapper (FIG. 10), or needle valve plugs (FIGS. 12-14). The obstructor and openings provide means to variably vent a pair of pressure fluid passages downstream from flow restrictors. Responder means, e.g. amplifier and/or load cylinders, are connected to the fluid passages. Feedback means from the amplifier and/or load cylinder variably vent the pair of fluid passages opposite to the variation by the obstructor. The feedback means comprises variable cross section surface passages in the amplifier or load or receiver piston or several of these or in the walls of the cylinders surrounding these pistons.
The responder means of the invention can be actuated by other forms of transmitter than those described above in which the transmitter variably vents a pair of fluid passages downstream from flow restrictors therein, the fluid passages upstream from the restrictors leading to a source of constant fluid pressure, and the pressures downstream from the restrictors being conducted by two fluid lines to the responder. Instead of variable venting, variable pressures can be generated by making the restrictors variable and conducting the downstream pressures by two lines to the responder. Furthermore, the transmitter may be modified to effect change in only one pressure. A single line may then be used between transmitter and responder. These various modifications will be described next.
Referring now to FIG. 17 there is shown an embodiment to the invention, the same as that of FIGS. 1 and 2 respectively insofar as the amplifier and receiver and concerned, but employing a modified form of transmitter. Like parts are given like reference numbers. In this embodiment, motor 41 acts to move spool 39 axially in cylinder 31 to vary the position of lands 43 and 45 relative to ports 27 and 29, as in FIGS. 1 and 3. However, conduit 11A connected to cylinder 31 leads to a pressure source rather than to a reservoir. The pressure in lines 61 and 63 leading to amplifier piston 101 are varied in accordance with the degree of throttling, or obstruction, produced by spool 39. Thus this is an example of control by variable obstruction of a pressure source. There is always a sufficient flow from lines 61 and 63 to the return reservoir conduit, for example 85, 89, and 167, to prevent the pressure in lines 61 and 63 from building up to supply pressure despite the throttling effect of spool 39.
The operation of the embodiment illustrated in FIG. 17 is the same as that of the embodiment illustrated by FIG. 1, in that electric signals inputted through electric motor 41 move spool 39 to vary the pressure in lines 61 and 63. This differential pressure in turn moves amplifier piston 101, causing ports 109 and 110 to be opened to the reservoir and pump pressure, respectively. The differential pressure thus applied to load piston 119 causes it to move axially, moving connected clevis 124 to actuate a load (not shown). Negative feedback, in accordance with the preferred embodiment of the invention, is effected by grooves 89 and 91 in the amplifier and by grooves 135 and 137 in the load piston. The feedback provided by these grooves limits the travel of both the amplifier and load pistons so the load pistons movement varies in an amount directly related to the amount of electrical input to motor 41. The precise relationship, linear or otherwise, between the signal strength and load movement depends on the size and shape of the feedback grooves.
It should also be noted that, due to the fact that the end areas of piston rods 121 and 123 that are exposed to reservoir pressure are different, piston 119 comes to rest at a balance of forces, not pressures. If, however, the reservoir pressure is atmospheric pressure, then the pressure on clevis 124 will effect a precise compensation and piston 119 will come to rest with a balance of pressures in lines 113 and 115, (assuming the load on clevis 124 exerts no force when the clevis is at rest).
Referring now to FIG. 18, these is shown a construction similar to that of FIG. 17 except no amplifier is employed. Like parts bear like reference numbers. It will be seen that variable pressures downstream of throttling spool 39 at port 27 and 29 are applied directly to load piston 119 through lines 113 and 115. Negative feedback in accordance with the invention is effected by grooves 135 and 137 in the load piston. These grooves are always in position to vent some of the pressure fluid back to the reservoir so there will be no buildup of hydraulic fluid in lines 113 and 115 sufficient to lock the system.
Referring now to FIG. 19, there is shown another embodiment of the invention adapted for a single line connection between the transmitter and receiver. The construction is similar to that of FIG. 18 in that no amplifier is used and similar to that of FIG. 2 in that the transmitter functions by variably venting the working fluid rather than by variably throttling it to effect pressure change. Reference numbers for parts similar to those of FIG. 2 will be employed, increased by 200.
The transmitter of FIG. 19 employs a manual input in the form of lever 241, which moves spool 239 axially. By this means single line 224 is variably vented to return-to-reservoir conduit 251. Venting varies in accordance with the position of land 245 relative to ports 228 and 229.
Load piston 319 is connected on one side by fluid passage 263 and flow restrictor 221 to conduit 211, which leads to the source of pressure fluid passage. Fluid 224 is connected to passage 263 by branch line or passage 226. The flow of fluid in this branch passage is used to vary the pressure of the fluid in passage 263 applied to one side of load piston 319. Pressure on the opposite side of piston 319 is maintained constant, e.g. by connection through passage 285 leading to a conduit connected to a reservoir. Similarly, the area at the end of piston rod 321 is connected by passage 366 to conduit 368. This conduit leads to a source of fluid pressure that may or may not be the same pressure source as is connected to conduit 211.
By varying the pressure on the constant pressure end of load piston 319 and piston 321, the pressure required on the right of load piston 319 and piston rod 323 can be adjusted required to make the system responsive to movement of transmitter actuator 241.
Piston rod 323 is connected to clevis 324 for actuating a load (not shown). The aperture through which the clevis extends out of the receiver housing is sealed by O-ring 326. This prevents leakage from chamber 328 at the end of piston rod 323. The chamber is connected by passage 366 to conduit 367. This conduit leads to a reservoir. In accordance with the invention, negative feedback is achieved by the use of groove 337 in piston rod 323 that variably connects chamber 328 to fluid passage 353. Fluid passage 353 is connected to line 224 and passage 226.
When actuator 241 is moved to allow venting to increase in line 224, fluid pressure drops in passage 226 causing piston 319 to move to the right as illustrated in the drawing. Such movement causes groove 337 to also move to the right whereby only its shallow left end portion connects passage 353 to chamber 328. Venting, by passage 353, is thereby reduced, raising the pressure in passage 226 and bringing piston 319 to rest.
When actuator 241 is moved to the left as shown in the drawing, venting is decreased in line 224. This results in a pressure rise in passage 226 causing piston 319 to move to the left. Such movement causes groove 337 to also move to the left whereby its deeper right ended portion connects passage 353 to chamber 328. This increases venting through passage 353, lowering pressure in passage 226 and bringing piston 319 to rest.
While the use of a single line connecting the transmitter and receiver has the advantage of structural simplicity, its operation is dependent upon the maintenance of predetermined pressure in the supply and reservoir conduits 251, 211, 296, 286, and 367. On the other hand, with the two line system previously described, only the pressure differential between the two lines is significant. Both single and dual line systems are described herein in order to illustrate the scope of the invention that is directed primarily to the negative feedback means that allows a load piston's movement to be a function of the movement of the transmitter actuator. This is true whether the actuator variably blocks a pressure source, blocks venting to a reservoir, or differentially changes the pressure in two lines.
Referring now to FIG. 20 there is shown an embodiment to the invention that is the same as that of FIG. 19, except the transmitter functions by variable throttling as in FIG. 18 instead of by variable venting as in FIG. 19. Like parts are given like numbers to the constructions shown in FIGS. 18 and 19, whereby the operation will be obvious and repeated description rendered unnecesary.
Briefly, movement of manual actuator 241 moves variable restrictor means 245 to variably throttle pressure fluid flowing from conduit 11A to line 224 and passage 226 to the right of piston 319. This causes piston 319 to move to the right or left according to whether pressure falls or rises. Negative feedback by groove 337 causes the initial pressure change in passage 226 to be eliminated, bringing the load piston to rest in a new position.
Referring to FIG. 21 there is shown an embodiment of the invention similar to that shown in FIG. 19. In this embodiment a single line is employed between transmitter and receiver and the transmitter functions by variable venting to create the desired pressure change. However, an amplifier is employed in this embodiment of the invention as was illustrated in FIGS. 2 and 17. As in FIG. 4, the amplifier, in this construction, is not provided with feedback means. Like parts are given like reference numbers.
Operationally, movement of manual actuator 241 to the left or right causes pressure to rise or fall respectively in line 224. This causes amplifier spool 101 to move to the left or right, which in turn causes load piston 319 to move to the left or right. Feedback groove 137 increases or decreases the venting of passage 153 when the piston rod 323 moves to the right or left, thereby producing negative feedback to return amplifier spool 101 to its original position and bring the load piston to rest.
It may be pointed out at this time that the feedback groove tapers in different directions according to the requirements of the particular embodiment of the invention so as to always yield negative feedback in the system. If groove 137 in FIG. 21 tapered in a direction opposite to that shown in the illustration, positive feedback would be created that would accelerate the movement of the load piston toward its limiting position in one direction or the other; instead of producing a load piston position that is a direct known function of the movement of the manual actuator.
To insure that feedback passage 153 is never blocked off completely by land 79 on the amplifier spool, a pin 401 is provided at the end of cylinder 65 in which moves the amplifier spool and limits its travel.
Referring now to FIG. 22 there is shown a variation of the amplifier piston illustrated by FIG. 21, constructed to incorporate a negative feedback groove 91. Negative feedback on the amplifier may be used in addition to or in place of negative feedback on the load pis |