Power tool and torque-responsive gear unit for a power tool

Abstract

The present specification relates to a two-speed power transmission for a power tool comprising a planetary gear (18) and a torque responsive gear shift mechanism (19) for directing torque through the planetary gear in a high torque / low speed mode or past the planetary gear in a low torque / high speed mode, and comprising a driving member, a driven member (27), and a number of coupling elements (30) arranged to intercouple in a first position the driving member (26) and the driven member and in a second position the planetary gear and the driven member, the driving member comprising a number of recesses (39) and axially acting first cam means (35) for cooperation with the coupling elements in the first position forming part thereof. The present specification also relates to power tool comprising such a gear unit and a method for controlling such a power tool.

Description

technical field [0001] The present invention relates generally to a power tool, and more particularly to a torque responsive gear unit for a power tool. Background technique [0002] Different types of power tools are known to be used in various industries, one common type being a power tool for tightening screws or bolts. [0003] One issue known to give rise to various design challenges in this field is that operating conditions and requirements for expected output tend to vary widely during use, for example with respect to speed and torque required during different parts of a typical working stroke. This is the case, for example, with tightening tools, where during the initial stages of tightening during screw or nut tightening, the so-called run down, the required torque is low and the rotational speed ideally high to reduce the operating effort. The time required, while in the actual tightening phase, that is, during the actual tightening of the joint, the required tor...

AI Technical Summary

Problems solved by technology

[0007] However, there are still many problems associated with this transmission

For example, many such known transmissions require the operator to manually shift between a high speed / low torque mode and a low speed / high torque mode, thereby increasing the complexity of the operator's handling of the tool

Further, such transmissions by definition have high requirements for durability, strength and tolerances, making the design itself complex, and these requirements usually mean that such transmissions often require a lot of space, greatly increasing tool overall size of

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