Tools – Wrench – screwdriver – or driver therefor – Machine
Reexamination Certificate
2000-06-26
2001-12-18
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Machine
C081S063200
Reexamination Certificate
active
06330842
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to ratchet wrenches and, more particularly, to powered ratchet wrenches.
Conventional powered ratchet wrenches generally employ an electrical or pneumatic motor coupled to a ratchet mechanism through a transmission. The output shaft of the motor turns a transmission input shaft, and the output shaft of the transmission turns a crankshaft. The crankshaft eccentric rotation oscillates a ratchet yoke. The movement of the ratchet yoke causes a pawl to engage and rotate the ratchet spindle or tool head of a ratchet mechanism to rotate so that a bolt, nut, or other threaded part engaged therein is tightened or loosened.
The ratchet yoke comprises a large component within the head of the wrench, and necessitates a wrench head that is larger than would otherwise be necessary if the yoke could be eliminated. It is desirable to provide a wrench head as small as possible to reach into restricted spaces, and any measure that reduces the size of the wrench head is considered an important advance in the art.
SUMMARY OF THE INVENTION
The present invention generally comprises a power driven ratchet tool that features a novel drive mechanism that provides a compact wrench head.
The tool includes a generally tubular handle having a drive motor and transmission supported therein, and a driver assembly extending axially from the handle and releasably secured thereto. The driver assembly includes a box end socket driver assembly for engaging a hex head bolt or nut, or a square drive opening. A plurality of interchangeable driver assemblies may be provided to engage a wide range of sizes of bolt heads or nuts.
Each driver assembly includes a tubular housing having a drive shaft extending axially therethrough and adapted to couple at the proximal end to the motor and transmission in the handle. The distal end of the housing supports a wrench head housing that flares distally to a rounded end. A drive socket is supported in the wrench head housing, and includes an aperture therethrough configured to engage a standard threaded component. The drive socket also includes gear teeth extending about the periphery thereof within the head housing. At least one socket detent ball is supported in the head housing and resiliently biased to impinge on the gear teeth to restrain rotation of the drive socket.
The drive shaft supports an eccentric crank at its distal end, the crank being disposed within the wrench head housing. A drive pawl pin is disposed within the head housing, extending transversely to the axis of the drive shaft and parallel to the axis of the drive socket. The drive pawl pin includes an opening therethrough to receive the crank freely, whereby the drive pawl pin is driven to reciprocate. The drive pawl pin is constrained by channels in the housing to translate within the housing in a reciprocal arcuate path that is transverse to the drive shaft axis and concentric to the drive socket axis.
A drive pawl includes a central aperture for receiving and securing the drive pawl pin in freely rotating fashion, whereby the drive pawl is driven to translate reciprocally with the drive pawl pin. The drive pawl also include a plurality of drive teeth extending eccentrically therefrom to releasably engage the gear teeth of the drive socket. A pawl spring impinges on the drive pawl to bias the pawl to rotate about the drive pawl pin.
As the drive shaft rotates, the crank moves the drive pawl pin laterally in a first direction in the head housing, causing the drive pawl to translate therewith. The pawl spring rotates the drive pawl so that the pawl teeth engage the gear teeth, whereby the pawl translation results in incremental rotation of the drive socket. As the crank moves in the second, opposite direction, the pawl teeth disengage the drive socket gear teeth, and the drive pawl in translated to return laterally and re-engage the drive socket gear teeth when the crank begins to translate in the first direction once again. The socket detent ball prevents counter-rotation of the drive socket by the return motion of the drive pawl. This cycle is reiterated quickly and indefinitely until the threaded component engaged by the drive socket is completely tightened or loosened, under the control of the wrench user.
REFERENCES:
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patent: 3786698 (1974-01-01), Diehl et al.
patent: 4339968 (1982-07-01), Krieger
patent: 4346630 (1982-08-01), Hanson
patent: 4372181 (1983-02-01), Tinsley
patent: 4765210 (1988-08-01), Mierbach et al.
patent: 5022289 (1991-06-01), Butzen
patent: 5203238 (1993-04-01), Ferguson
patent: 5351583 (1994-10-01), Szymber et al.
patent: 5450773 (1995-09-01), Darrah et al.
patent: 5584220 (1996-12-01), Darrah et al.
patent: 5896789 (1999-04-01), Giardino
patent: 5967002 (1999-10-01), Pijanowski
patent: 6065374 (2000-05-01), Taggart
patent: 6148694 (2000-11-01), Spirer
Smith James G.
Zimmerman Harris
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