Tools – Including tool driving by impact delivering component or... – Structurally constrained to arcuate movement
Reexamination Certificate
2002-04-11
2004-01-20
Hail, III, Joseph J. (Department: 3723)
Tools
Including tool driving by impact delivering component or...
Structurally constrained to arcuate movement
C173S093500
Reexamination Certificate
active
06679143
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to impact tools and, more particularly, to manually operated impact tools such as an impact wrench which tightens or loosens a nut from a mating threaded shaft.
2. Prior Art
Impact based or impact assisted wrenches of the prior art operate using electric, pneumatic and in some cases hydraulic power to loosen and/or tighten fasteners such as nuts threaded on a mating treaded stud. The impact force generated by such wrenches greatly assists the loosening and tightening operation of such devices by generating a large impulsive force at the fastener interface. As the result, and in many cases due also to the generated stress waves that travels across the male and female fastener surfaces, such wrenches are operated with a significantly smaller operator effort. In certain situations, the large forces and/or moment and/or torque that has to be applied to a manually operated wrench to begin to open the fastener may cause its failure, particularly since such forces cannot usually be applied perfectly symmetrically, i.e., only in the direction that would open the fastener without unwanted added forces. For example, an operator applying a torque to a manually operated socket wrench to open a bolt may also apply a large shearing force and/or bending moment while exerting his maximum effort to open the fastener and thereby may cause the bolt to shear off during the procedure. Such failures seldom occur while using impact based wrenches since the operator does not have to exert his or her maximum effort in the above manner to operate the wrench.
It can safely be claimed that the relative ease with which impact based wrenches are operated to loosen or tighten various fasteners is well appreciated by their users. However, such wrenches require electric, pneumatic or some other type of generally electric based power in order to operate. In addition, such systems are generally heavy, bulky and expensive to be carried by the operator to all sites. This is particularly the case for the infrequent user such as a driver who may require the wrench in case of a flat tire to loosen and fasten the tire bolts or nuts.
A need therefore exists in the art for manually operated impact wrenches that are simple to use, light weight and inexpensive, particularly for the casual user and professional user who does not have access to a power source at the work site or who does not want to carry a heavy load to a site or may seldom face the need for its use.
SUMMARY OF THE INVENTION
Therefore it is an object of the present invention to provide a manually operated impact tool which offers the same advantages as the pneumatically and electrically powered impact tools of the prior art.
The primary objective of the present invention is to provide a basic manually powered mechanism that can be used to construct various wrenches and other similar tools. Hereinafter, the word wrench is used to mean the tools used to tighten and loosen (open) bolts and nuts of various kinds, tools with hexagonal heads, screw drives of various kinds, tools for rotating various tubes and rods, and other similar tools that are used to manually exert a twisting torque, a twisting moment, an axial or lateral force, or their various combinations. Such tools are generally used to tighten or loosen fasteners but may also be used to act as a chisel or the like for removing, e.g., welds, or for tools for cutting a wire or tree branches or the like, where unassisted direct transmission of operator generated force, even when the commonly used force amplification mechanisms are used, is not enough to accomplish the desired action. All the tools that are described in the following embodiments have a common mechanism of operation, namely the manually generated impact type of force or torque or moment or any of their combinations.
The basic operating principle of the present invention is as follows. In regular wrenches, a force or twisting torque or moment is applied to the wrench handle which is transmitted to the bolt head (or the nut or screw head or the like) to loosen (open) or tighten (close) it. Hereinafter, all the operation of the wrench is described in terms of a bolt being loosened or tightened but the same description applies to the operation of the wrench on any other type of fastener. The maximum force, torque or twisting moment that can be applied by a regular wrench is dependent on the effective lever arm or any other type of mechanism used in the construction of the wrench and the force, torque or twisting moment that the operator can produce. Impact wrenches, however, work on the principle of impact. In the impact wrenches of the present invention, an operator applies the force, torque or the twisting moment to a handle of the impact wrench which in turn loads an impact spring (in compression or tension depending on the mechanisms design and torsionally or in bending if torsional or bending type of springs are used). One end of the impact spring is rigidly attached to the wrench handle body (the driving member) and the other end is attached to an impact mass which is held fixed relative to the wrench body that holds the bolt head by a movable stop mechanism. The work done by the operator on the wrench is thereby transformed into a potential energy that is stored in the impact spring. Then at a preset amount of handle rotation (considering that the fastener is tight and does not open while the handle is being rotated and the impact spring is being loaded) which corresponds to a certain amount of impact spring force and stored potential energy in the impact spring, the movable stop mechanism is released by the rotating handle. The impact mass is then accelerated forward and impacts on a provided site on the bolt holding part (the driven member) of the wrench, thereby providing an impact torque on the bolt in the direction of its opening. The amplitude of the impact force is definitely higher than the maximum level of force that was applied by the operator. By using relatively rigid material with minimal internal damping and by minimizing friction force on the impact mass, the change in the direction of the impact mass momentum during impact further increases the peak force applied to the bolt head in the desired direction (e.g., opening or closing).
Accordingly, a manually operated rotatable impact tool is provided. The impact tool comprises: a driven member having means for retaining and driving a fastener about an axis, the driven member further having at least one impact stop offset from the axis; a driving member rotatably connected to the driven member for driving the driven member about the axis to loosen or tighten the fastener; an impact mass movable along a path in communication with the impact stop; energy storing means for storing energy upon rotation of the driving member; and energy releasing means for releasing the stored energy and allowing it to be at least partially transferred to the impact mass such that the impact mass accelerates and strikes the impact stop upon the release of the stored energy.
REFERENCES:
patent: 3156309 (1964-11-01), Swenson
patent: 4106572 (1978-08-01), Anderson
patent: 4184552 (1980-01-01), Anderson
patent: 4243109 (1981-01-01), Anderson
patent: 4293044 (1981-10-01), Anderson
patent: 4474091 (1984-10-01), Russ
patent: 4794830 (1989-01-01), Gross et al.
patent: 5095784 (1992-03-01), Garver
Rastegar Jahangir
Spinelli Thomas
Hail III Joseph J.
Omnitek Partners LLC
Shakeri Hadi
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