CLOTH PRESSER LIFTING DEVICE OF SEWING MACHINE

PROBLEM TO BE SOLVED: To eliminate the fixed state of the height of a cloth presser at the electric power cut off. SOLUTION: The cloth presser lifting device includes: an air cylinder 4 for lifting the cloth presser 5; a first electromagnetic valve 10 feeding air pressure from an air pressure source 20 to respective air chambers 4U and 4D of the air cylinder; an operation input means 30 for operating the cloth presser; a control means 40 for switching the height of the cloth presser by controlling the first electromagnetic valve and stopping the cloth presser on the way according to the length of the lowering time; preliminary exhaust pathways 71 and 72 disposed in the respective air chambers of the cylinder; check valves 73a disposed in the respective preliminary exhaust pathways; a closing pressure feeding pathway 74 for feeding air pressure to the respective check valves; a second electromagnetic valve 75 switchable an air pressure feeding state or an atmospheric air releasing state to the exhaust side of the respective check valves; and a presser releasing control circuit 77 for switching the state of the second electromagnetic valve to the air pressure feeding state when the electricity is carried from a main power supply or to the state of releasing to the atmosphere when the main power supply is cut off. COPYRIGHT: (C)2010,JPO&INPIT