AUTOMATIC PRESSING FOOT LIFTING THREAD-LOOSENING MECHANISM AND SEWING MACHINE

摘要

Disclosed are an automatic pressing foot lifting thread-loosening mechanism and a sewing machine. The pressing foot lifting thread-loosening mechanism comprises a motor (1), a pressing foot assembly, a thread-loosening assembly, a pressing foot lifting thread-loosening cam (2), and a pressing foot lifting thread-loosening top plate (3). The pressing foot lifting thread-loosening cam (2) is arranged on a rotating shaft (4) of the motor (1), a first tension spring base (5) being arranged on the end of the pressing foot lifting thread-loosening cam (2) furthest from the rotating shaft (4) of the motor (1), the pressing foot lifting thread-loosening top plate (3) comprising a first bifurcated part (6), a second bifurcated part (7), and a third bifurcated part (8), the middle of the pressing foot lifting thread-loosening top plate (3) being rotatably connected to a machine shell (10) by means of a pressing foot lifting thread-loosening pin (9), a second tension spring base (11) being arranged on the outer end of the second bifurcated part (7), the first tension spring base (5) and the second tension spring base (11) being connected by means of a tension spring (12) such that the surface of an outer column of the second tension spring base (11) is in contact connection with the surface of an outer column of the pressing foot lifting thread-loosening cam (2), the outer end of the first bifurcated part (6) being positioned below a pressing rod guide bracket (13) of the pressing foot assembly, and the outer end of the third bifurcated part (8) being positioned at one side of a thread-loosening auxiliary nail (14) of the thread-loosening assembly. The thread-loosening and pressing foot lifting action of the automatic pressing foot lifting thread-loosening mechanism is controlled by a motor; the structure is compact, and the pressing foot lifting thread-loosening cam (2) is in contact connection with the second tension spring base (11) to drive the pressing foot lifting thread-loosening top plate (3) to rotate; there is little noise, and production costs are low.