GB2380962A

GB2380962A - Torsion limiting member for an impact mechanism

Info

Publication number: GB2380962A
Application number: GB0126774A
Authority: GB
Inventors: Hsin Chi Chen
Original assignee: Tranmax Machinery Co Ltd
Current assignee: Tranmax Machinery Co Ltd
Priority date: 2001-10-17
Filing date: 2001-11-07
Publication date: 2003-04-23
Also published as: FR2830784A3; GB0126774D0; JP3086271U

Abstract

A torsion limiting device 10 of an impact tool comprises an anvil 40 having a shaft portion 41, the anvil being capable of rotating around the shaft portion, and at least one hammer 30 having a body 31 which moves along a predetermined direction and around the shaft portion for driving the shaft portion to rotate. At least one retaining portion 51,53 is installed between the body and the shaft portion. When the body (31) drives the shaft portion to rotate, the body is connected to the shaft portion. Preferably the device forms part of a pneumatic tool, eg an impact wrench.

Description

TORSION LIMITING MEMBER FOR AN IMPACT MECHANISM FIELD OF THE INVENTION The present invention relates to a pneumatic tool, and particularly to a torsion limiting member for an impact mechanism.

BACKGROUND OF THE INVENTION The pneumatic tools are necessary devices In current society Some pneumatic tools are aimed at outputting power steadily, and some are aimed at outputting a larger torsional force For example, in general, for screwing screws, not all pneumatic tools have the same output condition When it IS desired to release a tightened screw or a nut or tighten a screw or a nut, the desired torsion is not Identical. If releasing a screw, a transiently larger torsional force IS necessary When it is desired to tighten a screw, a uniform force is required A too large torsion will make the screw to be too tight so that It possibly cracks For example the engagement and disengagement of a wheel rim has such a problem For example, an aluminum wheel rim IS engaged by a plurality of screws spaced with an equal space so as to be installed at a distal end of a driving means. In general, it is required that the screws must be uniformly distributed and thus the rim will not crack due to a too large torsion applied In a point so that the vehicle can steadily move.

For example, U S Patent 6, 070, 674 discloses a pneumatic tool which IS in general used m the maintenance of a wheel rim. In that,

two hammers apply force to an anvil so that the anvil rotates for generating a required rotating output force so as to tighten or release a screw This means has a larger torsion which is suitable for releasing a screw while it is improper In other words, the output torsion can not be controlled in a proper range Furthermore, It is impossible to control all the screw to have uniform tightness, and thus it is dangerous in driving SUMMARY OF THE INVENTION Accordingly, the primary object of the present invention is to provide a pneumatic tool which retains the output torsion in a proper range as screwing Thereby, the tightness of the screws can be controlled in a predetermined range for that the screws apply uniform force on an object Another object of the present invention is to provide a torsion limiting member for an impact mechanism, wherein as the pneumatic tool rotates, the torsion outputs toward a regular direction and an opposite direction are different. Therefore, the operations of such as combining a wheel rim can be performed in a preferably way To achieve the object, the present invention provides a torsion limiting member for an impact mechanism comprising : an anvil having a shaft portion, the anvil being capable of rotating around the shaft portion; at least one hammer having a body which moves along a predetermined direction and around the shaft portion for driving the shaft portion to rotate At least one retaining portion is installed between the body and the shaft portion When the body drives the shaft portion to rotate, the body is connected to the shaft portion.

The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing BRIEF DESCRIPTION OF THE DRAWINGS Fig 1 is an exploded perspective view of a preferred embodiment of the present invention.

Fig 2 is an assembled perspective view of the preferred embodiment of the present invention Fig 3 is a cross section view of a preferred embodiment of the present invention which is rotated along the line A-A of Fig. 2 Fig. 4 is a cross section view of a preferred embodiment of the present invention which is rotated along a direction opposite the line A-A of Fig. 2. Fig 5 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to figures, a preferred embodiment of the present invention is Illustrated The torsion limiting member 10 for an impact mechanism of the present invention Includes a hammer seat 20, two hammers 30, an anvil 40, and two retaining portions 50.

The hammer seat 20 has a long frame 21. An opened hammer chamber 22 is Installed in the center of the frame 21. Two stud holes 23 penetrate through the frame 21 and are connected to the hammer chamber 22 The axis of the hole is parallel to the long axis of the frame 21. A via hole 24 penetrates through a wall corresponding to one end of the long axis of the frame 21 and is communicated with the hammer chamber 22 A receiving hole 25 is formed on a wall of the hammer chamber 22 corresponding to another end of the long

axis of the frame 21 The hole axis is coaxial with the via hole 24 The ratchet hole 26 is adjacent to one side of the receiving hole 25 and penetrates to another end of the long axis of the frame 21 The two hammers 30 are block-like body having the same structure Each hammer has a plate like body 31 with a proper thickness A cambered pivot concave portion 32 is formed on one lateral plate of the body 31 A limiting sliding groove 33 is formed in the body 31 opposite to the concave portion 32 A cavity 34 penetrates through the two lateral plates of the body 31 Two ear portions 35 are protruded from two sides of walls corresponding to the concave portion 32.

The anvil 40 is a rod-like shaft portion 41 with a proper length Two cambered block-like jaw portions 42 are protruded from the shaft portion 41 and are installed with 180 degrees Two beaten surfaces 43 are at the lateral ends of the two jaw portions 42 The retaining portion 50 includes two first embedding grooves 51 Installed on the anvil 40 The first embedding grooves 51 are formed adjacent jaw portions 42 and at another side of the beaten surfaces 43. The grooves are parallel with the axis of the shaft portion 41. The first embedding groove 51 is formed with a first strip 52 Two second embedding grooves 53 are formed on the ear portions 35 of the two hammers 30 The width of the second embedding groove 53 may receive the first strip 52 so that the width at the distal end of the ear portion 35 may receive the second strip 54 which is engaged with the first embedding groove 51.

The combination of the hammer seat 20, hammers 30 and anvil 40 are identical to those In the prior art Two proper studs 60 are utilized to pivotally connect the hammers 30 to the hammer chamber 22 of the hammer seat 20 so that the limiting sliding groove 33 is engaged to the stud 60, while the hammer 30 swings In a proper range. However, the structure is the same those m the prior art, and thus the details will not be described herein.

With reference to Fig 3, when a force is applied to the hammer seat 20 so as to rotate with a direction indicated in the drawing The two hammers 30 Installed in the hammer chamber 22 are rotated therewith When the ear portion 35 contacts the jaw portion 42 of the anvil 40, the retaining portion 50 will be engaged with the first embedding groove 51 and second embedding groove 53 through the first strip 52 and second strip 54. Then, the hammers 30 and the anvil 50 are retained with a proper connection Thereby, in the whole process of rotating the hammer seat 20, the anvil 50 is driven by the hammers 30 through the retaining portion 50. No too large torsion occurs Thus, the pneumatic tool of the present invention may retain the output torsion in a proper range as screwing Thereby, the tightness of the screws can be controlled in a predetermined range for that the screws apply uniform forces on an object.

Referring to Fig. 4, when the hammer seat 20 rotates oppositely.

Generally, the screw is released, and thus a transient large torsion is necessary. The present invention may apply an impact as in the prior art Namely, the ears 35 of the hammers 30 impacts the beating surface 43 of the jaw portion 42 of the anvil 40 intermittently so that the anvil 40 may acquire a transient larger torsion for

processing above process In should be emphasized, In the rotating direction of Fig. 3, at the time that the hammer 30 beats the anvil 40 firstly Namely the retaining portion 50 connects the hammers 30 and the anvil 40 properly No relative motion occurs between the hammers 30 and the anvil 40 Then, in the proceeding operation, a torsion in a proper range can be retained Furthermore, as the anvil 40 is impacted by the hammers 30, no too large torsion occurs Therefore, the conventional Impact means is improved Thereby, the bad effect of a transient large torsion from the impact of the hammer can be overcome. Therefore, as the present invention is used in the maintenance of a wheel rim, a proper torsion is provided for screwing screws Thus, each screw applies a uniform force to the wheel rim. Thereby, a too large screwing force to induce the crack of rims is avoided, and thus a safe travel is assured Although the present invention has been described with reference to the preferred embodiments, it will be understood that the invention is not limited to the details described thereof Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims

Claims

What is claimed is: 1. A torsion limiting member for an impact mechanism comprising an anvil having a shaft portion, the anvil being capable of rotating around the shaft portion, at least one hammer having a body which moves along a predetermined direction and around the shaft portion for driving the shaft portion to rotate, characterized In that at least one retaining portion installed between the body and the shaft portion; when the body drives the shaft portion to rotate, the body is connected to the shaft portion.
2. The torsion limiting member for an Impact mechanism as claim in claim 1, wherein retaining portion is formed at a connection of the shaft portion and the body and has an embedding strip and an embedded groove which are coupled with one another; the orientation of the groove IS parallel to an axis of the shaft portion.
3 The torsion limiting member for an impact mechanism as claim in claim 1 or 2, wherein the anvil Includes at least one jaw portion installed at the shaft portion for receiving an Impact force as the body moves along an opposite direction of the predetermined direction.
4. The torsion limiting member for an impact mechanism as claim in claim 3, wherein the jaw portion has a beaten surface for being subjected to an impact force from the body

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5 The torsion limiting member for an impact mechanism as claim In claim 4, wherein the retaining portion IS Installed between the body and the side of the jaw portion opposite the beaten surface 6 The torsion limiting member for an impact mechanism as claim m claim 3, wherein there are two hammers, the anvil has two jaw portions which are spaced with 180 degrees and protrude from the shaft portion for suffering the impact force from the body 7 The torsion limiting member for an impact mechanism as claim m claim 1, wherein there are two hammers and two retaining portions, each retaining portion is installed between the body of the hammer and the shaft portion.

8 The torsion limiting member for an impact mechanism as herein described with reference to the accompanying drawing.