Tools – Wrench – screwdriver – or driver therefor – Responsive to torque on work
Patent
1998-09-10
2000-05-16
Smith, James G.
Tools
Wrench, screwdriver, or driver therefor
Responsive to torque on work
173176, B25B 23157
Patent
active
060621141
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a power nutrunner of the type having a planetary type reduction gearing and a torque limiting release clutch.
In particular, the invention concerns a power nutrunner in which the release clutch is disposed between a ring gear included in the reduction gearing, wherein a first cam means is provided on the ring gear, a second cam means is provided on an annular thrust element, two or more rolling elements are located between the thrust element and the ring gear to engage the first and second cam means, and a spring means is arranged to exert an axial bias load on the thrust element to maintain a torque transferring engagement between the first and second cam means.
A power nutrunner of the above type is previously described for instance U.S. Pat. No. 3,834,467. The nutrunner shown in this patent comprises a planetary reduction gearing having a rotatable but axially immovable ring gear, and a torque limiting release clutch including a spring biassed thrust element as well as cam means on the thrust element and the ring gear.
A significant feature of this known nutrunner is its relatively large axial dimensions. This is due to the fact that the release clutch including the thrust element is located axially separated from the ring gear. The result is a rather long tool housing. However, this is not a drawback in the type of tools illustrated in this patent, namely an angle nutrunner, because a long tool housing with a widely offset tool handle promotes an easier reaction torque counteraction by the operator.
In contrast to angle nutrunners, a straight pistol type tool need to be shorter in order to enhance a comfortable and effective handling of the tool as well as to reduce weight. The problem to which the invention is a solution arises when using this previously known type of reduction gearing/clutch mechanism in a pistol type tool. The axial dimension of the tool housing tends to be too large to meet the demands for a handy tool.
The main object of the invention is to provide a power nutrunner of the above described type in which the reduction gearing/clutch mechanism is axially very compact in order to keep down the overall lenght of the tool.
Other objects and advantages of the invention will appear prom the following specification and claims.
A preferred embodiment of the invention is below described in detail with reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a longitudinal section through the front part of a power nutrunner according to the invention.
FIG. 2 stows a fractional section through the power nutrunner shown in FIG. 1 but located in a different plane
FIG. 3 shows a side elevation of the release clutch included in the power nutrunner shown in FIG. 1.
DETAILED DESCRIPTION
The nutrunner illustrated in the drawing figures comprises a motor unit 10 the forward end portion only of which is shown in FIG. 1. Since the motor unit 10 does not form any part of the invention a detailed description thereof is not needed and is, therefore, left out of this specification.
To the motor unit 10 there is bolted a housing 11 for a reduction gearing 12 and a torque limiting release clutch 13. An output spindle 14 is connected to the motor unit 10 via the reduction gearing 12 and is provided with a chuck 15 for attachment of a screw joint engaging tool implement. At its forward end, the housing 11 is provided with an end wall 16 in which the output spindle 14 is rotationally journalled. The end wall 16 is formed with an internal neck portion 17 for providing a proper guidance for the output spindle 14. A bushing 18 at the front end of the end wall 16 forms a bearing for the output spindle 14 and is formed with an annular shoulder for transferring axial forces from the spindle 14 to the housing 11. A lock ring 19 and a shock absorbing resilient ring 20 are mounted on the spindle 14 for engagement with the shoulder of the bushing 18. In the opposite direction, the spindle 14 is axially locked by a lock ring 21 coopera
REFERENCES:
patent: 3834467 (1974-09-01), Fuchs
patent: 4834192 (1989-05-01), Hansson
patent: 4842078 (1989-06-01), Hansson
patent: 4898249 (1990-02-01), Ohmori
patent: 5076120 (1991-12-01), Lin
Atlas Copco Tools AB
Smith James G.
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