The present invention relates to improvements of a workpiece feeding device in a sewing machine, which, in particular, is installed with an endless feeding member such as a feed wheel, a feed belt or a feed chain steadily contacting a workpiece.
In U.S. Pat. No. 4,271,776 there is disclosed a sewing machine having a feeding device with such an endless feeding member intermittently driven by employing a one-way coupling in combination with a reversing gear device. As the one-way coupling is applied for converting an oscillating movement into an intermittent rotating movement of one direction, the reversing gear device serves for reversing the intermittent movement to make possible reversal of the feed movement for the workpiece to be sewn.
The reversing gear device of this known feeding device incorporates a clutch and gears for reversing the movement at which both elements are exposed to wear. Furthermore, the known feeding device is composed of an extensive number of elements of high quality so that this feeding device cannot be produced at low cost.
In U.S. Pat. No. 3,141,428 there are employed one-way couplings in a plurality of arrangements in which the individual couplings are separately and in different phases driven so as to generate a quasi rotating movement. To achieve such a movement a uni-directional arrangement of the couplings is necessary, i.e. the one-way couplings are arranged so as to transmit a torque in a common direction. By arranging one-way couplings in this manner, the reversing of the output movement may be achieved only with the application of a reversing gear device, as disclosed in the first-mentioned U.S. patent.