Device for controlling the pressure of fabric pressure shoes on sewing machines or the like

Abstract

An automatic control device that basically employs a pneumatic system that controls the pressure exerted on the shaft of the fabric pressure shoe, pressure that was traditionally exerted by spring systems or in any case mechanical-type systems that were always based on the pressure or the pull of a spring. Basically automatic control device ( 1 ), installed above shaft ( 2 ) on which fabric pressure shoe ( 3 ) is mounted, consists of cylinder ( 4 ) in the chamber of which piston ( 5 ) slides. The chamber of cylinder ( 4 ) is connected at the top to a tube ( 8 ) that leads to pneumatic control system ( 9 ). This system includes pressure regulator ( 10 ) of a type suitable for performing precision control of the pressure in the air circuit.

1 . Device for automatic control of the pressure exerted by the fabric pressure shoes of preferably industrial-type sewing machines characterized by the fact that it employs a pneumatic system that includes at least one cylinder ( 4 ) in which piston ( 5 ) slides, piston that is connected, through special connections ( 6 ) to shaft ( 2 ) of fabric pressure shoe ( 3 ) and by the fact that the inner chamber of said cylinder ( 4 ) is connected, by special tubes ( 8 ), to a pneumatic control system which includes special pressure regulators ( 10 ) equipped with stabilizing valves or the like with variable settings.  
     
     
         2 . Device for automatic control of the pressure exerted by fabric pressure shoes according to  claim 1 , characterized by the fact that said piston ( 5 ), which is connected to shaft ( 2 ) of the shoe through arm ( 6 ), is provided, along its outer edge, with a ring-shaped groove designed to house an elastic ring or “O-ring” seal ( 7 ) with a round and floating type cross section.  
     
     
         3 . Device for automatic control of the pressure exerted by fabric pressure shoes according to  claim 1 , characterized by the fact the cylinder chamber is connected at the top to a tube ( 8 ) which terminates at a pneumatic control system ( 9 ) that includes special pressure regulator ( 10 ) of the type designed to control the pressure in the air circuit with precision.  
     
     
         4 . Device for automatic control of the pressure exerted by fabric pressure shoes according to  claim 1 , characterized by the fact that this control is performed by pressure regulator ( 10 ) through a suitable pressure reducing and stabilizing valve and the delivery rate of this valve can be modified by pressure regulator ( 11 ).  
     
     
         5 . Device for automatic control of the pressure exerted by fabric pressure shoes according to  claim 1 , characterized by the fact that auxiliary compensation device ( 12 ) is inserted between said cylinder ( 4 ) and said pressure regulator ( 10 ) and compensates for small variations in pressure before causing the pressure regulator valve to operate.  
     
     
         6 . Device for automatic control of the pressure exerted by fabric pressure shoes according to  claim 1 , characterized by the fact that a second outlet ( 14 ) can be installed in the lower part of cylinder ( 4 ) to which an auxiliary pneumatic valve can be connected designed to help lift the shoe when introducing and extracting the fabric.  
     
     
         7 . Device for automatic control of the pressure exerted by fabric pressure shoes according to  claim 1 , characterized by the fact that the connection between said compensation device and said fabric pressure shoe shaft, performed using arm ( 6 ), can also be obtained in parallel with a suitable mechanical connection or joining component.