Head of a wrench handle

A head of a wrench comprises a hole having a center and a radius. The head further includes a compartment communicated with the hole. A wall defining the compartment has a center of curvature and a radius of curvature. A ratio between the radius of curvature of the wall and the radius of the hole is equal to or greater than 0.5, but less than 1. A distance between the center of the hole and the center of curvature of the wall is selected to form a deeper compartment to thereby improve the torque-bearing capacity.

 

What is claimed is:

1. A head of a wrench comprising a hole (A) having a center (OA) and a radius (RA), the head further including a compartment (E) communicated with the hole (A), a wall (C) defining the compartment (E) having a center (OB) of curvature and a radius (RB) of curvature;

wherein a ratio between the radius (RB) of curvature of the wall (C) and the radius (RA) of the hole (A) is defined as follows:

(0.5.ltoreq.RB/RA<1)

and

wherein a distance (R1) between the center (OA) of the hole and the center (OB) of curvature of the wall (C) is defined as follows:

R1>RA-0.328*RB.

2. A combination of a head of a wrench and a pawl comprising:

a head including a hole (A) having a center (OA) and a radius (RA), a drive gear being rotatably received in the hole of the head, the head further including a compartment (E) communicated with the hole (A), a wall (C) defining the compartment (E) having a center (OB) of curvature and a radius (RB) of curvature; and

a pawl (D) slidably received in the compartment (E) of the head, the pawl including a toothed first side facing the hole and a second side facing away from the hole, the second side of the pawl including two bearing points (J.sub.2 and J.sub.4) selectively bearing against the wall (C) defining the compartment during ratcheting operation of the pawl, the toothed first side of the pawl including an engaging area (J.sub.3 J.sub.5) completely engaged with the drive gear during the ratcheting operation;

wherein a ratio between the radius (RB) of curvature of the wall (C) and the radius (RA) of the hole (A) is defined as follows:

(0.5.ltoreq.RB/RA<1)

wherein a distance (R1) between the center (OA) of the hole and the center (OB) of curvature of the wall (C) is defined as follows:

R1>RA-0.328*RB

wherein the bearing points (J.sub.2 and J.sub.4) on the second side of the pawl and the engaging area (J.sub.3 J.sub.5) on the toothed first side of the pawl are located by the following steps:

selecting an axis (X1) that passes the center (OA) of the hole (A) and that is at an angle of 3.degree.-15.degree. with a longitudinal axis (X) of the wrench, the axis (X1) intersecting the circle (A) at a first point (J.sub.1);

selecting a first line (J.sub.1 J.sub.2) that passes the first point (J.sub.1) and that is at an angle of 30.degree.-60.degree. with the axis (X1), the first line (J.sub.1 J.sub.2) intersecting the wall (C) defining the compartment (E) at a second point (J.sub.2), a third point (J.sub.4) symmetric to the second point (J.sub.2) with respect to the axis (X1) being located, the second point (J.sub.2) and the third point (J.sub.4) forming the bearing points on the second side of the pawl (D); and

selecting a second line (J.sub.2 J.sub.3) that passes the second point (J.sub.2) and that is parallel to the axis (X1), the second line(J.sub.2 J.sub.3) intersecting the circle (A) at a fourth point (J.sub.3), a fifth point (J.sub.5) symmetric to the fourth point (J.sub.3) with respect to the axis (X1) being located, an area between the fourth point (J.sub.3) and the fifth point (J.sub.5) forming the engaging area on the toothed first side of the pawl (D).

3. The combination as claimed in claim 2, wherein the first toothed side of the pawl includes at least one tooth on each of both sides of the engaging area of the pawl.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a head of a wrench handle with an improved torque-bearing capacity without increasing the manufacturing cost of the wrench.

2. Description of the Related Art

FIG. 1 of the drawings illustrates a handle head 100 of a conventional spanner type ratchet wrench. A gear 104 is rotatably mounted in a hole 100a in the head 100 and includes a polygonal inner periphery 101 for driving a fastener. The head 100 further includes a compartment 102 communicated with the hole 100a of the head 100. A pawl 103 is mounted in the compartment 102 and engaged with the gear 104. During ratcheting operation, the pawl 103 bears against a wall defining the compartment 102 at 105, which corresponds the third teeth counting from the leftmost tooth of the pawl 103 in FIG. 1. As can be seen from FIG. 1, the right portion of the pawl 103 is not supported such that when the force imparted to the pawl 103 reaches a critical value, no reactive force is obtained, and the pawl 103 will be disengaged from the gear 104 and move like a seesaw. The first three teeth will be damaged. This is owing to the fact that the compartment 103 is too shallow such that the pawl 103 merely engages with the gear 104 by only three effective teeth during the ratcheting operation. As a result, the torque-bearing capacity of the pawl 103 is poor. Enlargement of the head 100 would improve the torque-bearing capacity, yet the enlargement would contradict the benefit of the use of the spanner type ratchet type in a limited space.