Ratchet wrench having reinforced strength

A ratchet wrench includes a wrench body provided with a mounting hole and a receiving chamber, a ratchet wheel mounted in the mounting hole of the wrench body and provided with a plurality of ratchet teeth, and a pawl member mounted in the receiving chamber of the wrench body and having a first end provided with a plurality of locking teeth engaged with the ratchet teeth of the ratchet wheel and a second end provided with a sliding face slidable on the ratchet teeth of the ratchet wheel. Thus, the locking teeth of the pawl member are engaged with the ratchet teeth of the ratchet wheel closely and completely, so that the pawl member is combined with the ratchet wheel exactly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a ratchet wrench and, more particularly, to a oneway ratchet wrench for operating a workpiece, such as a screw, nut and the like.

2. Description of the Related Art

A conventional ratchet wrench in accordance with the prior art shown inFIGS. 6-9comprises a wrench body10having an end portion17provided with a mounting hole11and a receiving chamber15connected to the mounting hole11, a ratchet wheel40mounted in the mounting hole11of the wrench body10and having an outer wall provided with a plurality of ratchet teeth41, a pawl member20pivotally mounted in the receiving chamber15of the wrench body10by a pivot pin30and having a first side provided with a plurality of locking teeth21engaged with the ratchet teeth41of the ratchet wheel40, an elastic member23mounted in the receiving chamber15of the wrench body10and biased between a peripheral wall of the receiving chamber15of the wrench body10and a second side of the pawl member20to push the pawl member20toward the ratchet wheel40, a retaining ring800mounted in the mounting hole11of the wrench body10and abutting the ratchet wheel40to retain the ratchet wheel40in the mounting hole11of the wrench body10, and a substantially C-shaped snapping member900mounted in the mounting hole11of the wrench body10and snapped onto the retaining ring800to retain the retaining ring800in the mounting hole11of the wrench body10.

The wrench body10is provided with a positioning hole16connected to the receiving chamber15to allow passage of the pivot pin30. The end portion17of the wrench body10has an inner wall having a first side provided with a receiving groove13and a retaining groove14each connected to the mounting hole11and a second side provided with a limit rib12. The pawl member20is provided with a pivot hole22connected to the positioning hole16of the wrench body10to allow passage of the pivot pin30. The ratchet wheel40has an inner wall provided with a driving hole42to drive a workpiece, such as a screw, nut and the like. The ratchet wheel40has a first side provided with a limit groove73facing the receiving groove13of the wrench body10and a second side provided with a limit recess44abutting the limit rib12of the wrench body10. The retaining ring800is mounted on the ratchet wheel40and has an inner wall abutting the limit groove43of the ratchet wheel40and an outer wall abutting the receiving groove13of the wrench body10. The outer wall of the retaining ring800is provided with a locking groove810facing the retaining groove14of the wrench body10. Thus, the ratchet wheel40is limited by the retaining ring800and the limit rib12of the wrench body10. The snapping member900is snapped into the retaining groove14of the wrench body10and the locking groove810of the retaining ring800to retain the retaining ring800in the wrench body10.

In operation, referring toFIG. 8with reference toFIGS. 6 and 7, the driving hole42of the ratchet wheel40is mounted on a workpiece (not shown), such as a screw, nut and the like. In such a manner, when the end portion17of the wrench body10is rotated in the clockwise direction, the pawl member20is driven by the wrench body10to drive the ratchet wheel40in the clockwise direction. At this time, the ratchet wheel40applies a reaction force on the pawl member20in the counterclockwise direction to drive the locking teeth21of the pawl member20toward the ratchet teeth41of the ratchet wheel40, while the elastic member23pushes the locking teeth21of the pawl member20toward the ratchet teeth41of the ratchet wheel40, so that the locking teeth21at one end of the pawl member20are engaged with the ratchet teeth41of the ratchet wheel40closely, and the locking teeth21at the other one end of the pawl member20are spaced from the ratchet teeth41of the ratchet wheel40by pivot action of the pawl member20about the pivot pin30. In such a manner, the pawl member20is combined with the ratchet wheel40. Thus, when the end portion17of the wrench body10is rotated in the clockwise direction, the pawl member20is driven by the wrench body10to drive the ratchet wheel40in the clockwise direction as shown inFIG. 8so as to rotate the workpiece in the clockwise direction.

On the contrary, referring toFIG. 9with reference toFIGS. 6 and 7, when the end portion17of the wrench body10is rotated in the counterclockwise direction, the pawl member20is driven by the wrench body10to drive the ratchet wheel40in the counterclockwise direction. At this time, the ratchet wheel40applies a reaction force on the pawl member20in the clockwise direction to push the locking teeth21of the pawl member20to space from the ratchet teeth41of the ratchet wheel40, while the elastic member23is compressed by the pawl member20, so that the locking teeth21of the pawl member20are disengaged from the ratchet teeth41of the ratchet wheel40, and the pawl member20is released from the ratchet wheel40as shown inFIG. 9. Thus, when the end portion17of the wrench body10is rotated in the counterclockwise direction to drive the pawl member20in the counterclockwise direction, the ratchet wheel40is released from and not driven by the pawl member20, so that the wrench body10performs an idling rotation in the counterclockwise direction.

However, the locking teeth21at one end of the pawl member20are engaged with the ratchet teeth41of the ratchet wheel40, and the locking teeth21at the other one end of the pawl member20are spaced from the ratchet teeth41of the ratchet wheel40by pivot action of the pawl member20about the pivot pin30, so that the locking teeth21at one end of the pawl member20are easily worn out or broken during a long-term utilization, thereby decreasing the lifetime of the pawl member20and the ratchet wrench. In addition, the force applied on the pawl member20is concentrated on the pivot pin30to produce a stress concentration, so that the pivot pin30easily worn out or broken during a long-term utilization, thereby decreasing the lifetime of the pivot pin30and the ratchet wrench.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a ratchet wrench, comprising a wrench body having an end portion provided with a mounting hole and a receiving chamber connected to the mounting hole, a ratchet wheel mounted in the mounting hole of the wrench body and having an outer wall provided with a plurality of ratchet teeth, and a pawl member mounted in the receiving chamber of the wrench body and having a first side having a first end provided with a plurality of locking teeth engaged with the ratchet teeth of the ratchet wheel and a second end provided with a sliding face slidable on the ratchet teeth of the ratchet wheel.

The primary objective of the present invention is to provide a ratchet wrench having a reinforced strength.

Another objective of the present invention is to provide a ratchet wrench, wherein the locking teeth of the pawl member are engaged with the ratchet teeth of the ratchet wheel completely, so that the pawl member is combined with the ratchet wheel exactly without incurring detachment, thereby facilitating operation of the ratchet wrench.

A further objective of the present invention is to provide a ratchet wrench, wherein all of the locking teeth of the pawl member are engaged with the ratchet teeth of the ratchet wheel completely, so that the force applied by the locking teeth of the pawl member is shared by all of the locking teeth of the pawl member, and the locking teeth of the pawl member will not be worn out or broken during a long-term utilization, thereby enhancing the lifetime of the pawl member.

A further objective of the present invention is to provide a ratchet wrench, wherein the pawl member is movable freely in the receiving chamber of the wrench body to lock the wrench body and the ratchet wheel so that the rotation force between the wrench body and the ratchet wheel is distributed on the whole pawl member evenly and smoothly without incurring a stress concentration so as to reinforce the strength of the ratchet wrench, thereby preventing the pawl member from being worn out due to a larger rotation force, and thereby enhancing the lifetime of the ratchet wrench.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and initially toFIGS. 1-4, a ratchet wrench in accordance with the preferred embodiment of the present invention comprises a wrench body50having an end portion56provided with a mounting hole51and a receiving chamber55connected to the mounting hole51, a ratchet wheel70mounted in the mounting hole51of the wrench body50and having an outer wall provided with a plurality of ratchet teeth71, a pawl member60mounted in the receiving chamber55of the wrench body50and having a first side65having a first end provided with a plurality of locking teeth61engaged with the ratchet teeth71of the ratchet wheel70and a second end provided with a sliding face62slidable on the ratchet teeth71of the ratchet wheel70, an elastic member64mounted in the receiving chamber55of the wrench body50and biased between a peripheral wall550of the receiving chamber55of the wrench body50and a second side66of the pawl member60to push the pawl member60toward the ratchet wheel70, a retaining ring80mounted in the mounting hole51of the wrench body50and abutting the ratchet wheel70to retain the ratchet wheel70in the mounting hole51of the wrench body50, and a snapping member90mounted in the mounting hole51of the wrench body50and snapped onto the retaining ring80to retain the retaining ring80in the mounting hole51of the wrench body50.

The end portion56of the wrench body50has an inner wall having a first side provided with a stepped receiving groove53and an annular retaining groove54each connected to the mounting hole51and a second side provided with a radially and inwardly extending limit rib52. The receiving chamber55of the wrench body50has a substantially arc-shaped profile.

The pawl member60has a substantially arc-shaped profile and is movable freely in the receiving chamber55of the wrench body50to lock the wrench body50and the ratchet wheel70. The first side65of the pawl member60is a concave surface, and the second side66of the pawl member60is a convex surface. The locking teeth61of the pawl member60are engaged with the ratchet teeth71of the ratchet wheel70completely and extends through a distance that is half of a length of the first side65of the pawl member60. The sliding face62of the pawl member60is a recessed smooth surface and also extends through a distance that is half of the length of the first side65of the pawl member60. The second side66of the pawl member60has an end portion provided with a catch face63that is movable to abut the peripheral wall550of the receiving chamber55of the wrench body50. The catch face63of the pawl member60is located adjacent to the locking teeth61, and the locking teeth61of the pawl member60are located between the catch face63and the sliding face62.

The elastic member64is directed toward the locking teeth61and the catch face63of the pawl member60. The elastic member64is located adjacent to the sliding face62of the pawl member60, and the sliding face62of the pawl member60is located between the elastic member64and the locking teeth61of the pawl member60.

The ratchet wheel70has an inner wall provided with a driving hole72to drive a workpiece, such as a screw, nut and the like. The ratchet wheel70has a first side provided with a stepped limit groove73facing the receiving groove53of the wrench body50and a second side provided with a stepped limit recess74abutting the limit rib52of the wrench body50.

The retaining ring80is mounted on the ratchet wheel70and has an inner wall abutting the limit groove73of the ratchet wheel70and an outer wall abutting the receiving groove53of the wrench body50. The outer wall of the retaining ring80is provided with a locking groove81facing the retaining groove54of the wrench body50. Thus, the ratchet wheel70is limited by the retaining ring80and the limit rib52of the wrench body50.

The snapping member90is substantially C-shaped and is snapped into the retaining groove54of the wrench body50and the locking groove81of the retaining ring80to retain the retaining ring80in the wrench body50.

In operation, referring toFIG. 4with reference toFIGS. 1-3, the driving hole72of the ratchet wheel70is mounted on a workpiece (not shown), such as a screw, nut and the like. In such a manner, when the end portion56of the wrench body50is rotated in the clockwise direction, the pawl member60is driven by the wrench body50to drive the ratchet wheel70in the clockwise direction. At this time, the ratchet wheel70applies a reaction force on the pawl member60in the counterclockwise direction to drive the locking teeth61of the pawl member60toward the ratchet teeth71of the ratchet wheel70and to drive the catch face63of the pawl member60to press the peripheral wall550of the receiving chamber55of the wrench body50, while the elastic member64pushes the locking teeth61of the pawl member60toward the ratchet teeth71of the ratchet wheel70, so that the locking teeth61of the pawl member60are engaged with the ratchet teeth71of the ratchet wheel70closely, the sliding face62of the pawl member60evades the ratchet teeth71of the ratchet wheel70, and the pawl member60is combined with the ratchet wheel70. Thus, when the end portion56of the wrench body50is rotated in the clockwise direction, the pawl member60is driven by the wrench body50to drive the ratchet wheel70in the clockwise direction as shown inFIG. 4so as to rotate the workpiece in the clockwise direction.

On the contrary, referring toFIG. 5with reference toFIGS. 1-3, when the end portion56of the wrench body50is rotated in the counterclockwise direction, the pawl member60is driven by the wrench body50to drive the ratchet wheel70in the counterclockwise direction. At this time, the ratchet wheel70applies a reaction force on the pawl member60in the clockwise direction to push the locking teeth61of the pawl member60to space from the ratchet teeth71of the ratchet wheel70and to drive the catch face63of the pawl member60to space from the peripheral wall550of the receiving chamber55of the wrench body50, while the elastic member64is compressed by the pawl member60, so that the locking teeth61of the pawl member60are disengaged from the ratchet teeth71of the ratchet wheel70, the sliding face62of the pawl member60is movable on the ratchet teeth71of the ratchet wheel70, and the pawl member60is released from the ratchet wheel70as shown inFIG. 5. Thus, when the end portion56of the wrench body50is rotated in the counterclockwise direction to drive the pawl member60, the ratchet wheel70is released from and not driven by the pawl member60, so that the wrench body50performs an idling rotation in the counterclockwise direction.

Accordingly, the locking teeth61of the pawl member60are engaged with the ratchet teeth71of the ratchet wheel70completely, so that the pawl member60is combined with the ratchet wheel70exactly without incurring detachment, thereby facilitating operation of the ratchet wrench. In addition, all of the locking teeth61of the pawl member60are engaged with the ratchet teeth71of the ratchet wheel70completely, so that the force applied by the locking teeth61of the pawl member60is shared by all of the locking teeth61of the pawl member60, and the locking teeth61of the pawl member60will not be worn out or broken during a long-term utilization, thereby enhancing the lifetime of the pawl member60. Further, the pawl member60is movable freely in the receiving chamber55of the wrench body50to lock the wrench body50and the ratchet wheel70so that the rotation force between the wrench body50and the ratchet wheel70is distributed on the whole pawl member60evenly and smoothly without incurring a stress concentration so as to reinforce the strength of the ratchet wrench, thereby preventing the pawl member60from being worn out due to a larger rotation force, and thereby enhancing the lifetime of the ratchet wrench.