Temp. control for needle of sewing machine - has coil around oscillating needle connected into AC bridge to measure temp.

摘要

The temperature control has a coil (6) encircling an oscillating sewing needle concentrically and measuring its temp. without touching it. The reference value for the measurement is obtained by a stationary needle/coil combination (9,10). The difference is used to influence the frequency of the needle (1) oscillations and/or to control the cooling whenever the relative position of the needle w.r.t. the coil is equal to the relative position of the stationary reference needle (10) w.r.t. the reference coil. The two coils are located one in each arm of an a.c. bridge. The output voltage of the bridge is interrogated by a switch (19) controlled by markings on the machine's flywheel or other moving part.(DS).