Patent ID: 6116143
Filing Date: 2000-09-12
Classification: F15B

Abstract:
A controller for a double-acting fluid cylinder having a working piston movable in a forward direction by a first fluid volume, and in a rearward direction by a second fluid volume, said cylinder being operable by said controller under a source of fluid pressure having an associated fluid reservoir, and said controller comprising a multi-position flow control valve comprising:a plurality of sequentially arranged fluid ports including a pressure port (P) coupled in fluid communication with said source of fluid pressure, a first reversing port (A1) coupled in fluid communication with said first fluid volume of said cylinder and couplable in fluid communication with said port P, a second reversing-port (B1) coupled in fluid communication with said second fluid volume of said cylinder and couplable in fluid communication with said port P, a first by-pass port (A2) coupled in fluid communication with said first fluid volume of said cylinder and couplable in fluid communication with said port B1, a second by-pass port B2 coupled in fluid communication with said second fluid volume of said cylinder, a first reservoir port (T1) coupled in fluid communication with said reservoir and couplable in fluid communication with said port A1, and a second reservoir port (T2) coupled in fluid communication with said reservoir and couplable in fluid communication with said port B2; anda valve positioner having a plurality of valve elements including, in series, a first valve element, a second valve element, a third valve element, and a fourth valve element,whereby said valve positioner is displaceable from a null position wherein said port A1 is blocked by said first valve element, said port B1 is blocked by said second valve element, and said port T2 is blocked by said third valve element, to a first control position wherein said first valve element is displaced from said port A1 opening said port A1 in fluid communication with said port P admitting fluid pressure to said first fluid volume of said cylinder moving said working piston in said forward direction, said fourth valve element is at least partially displaced from said port B2 opening said port B2, and said third valve element is displaced from said port T2 opening said port T2 in fluid communication with said port B2 admitting fluid displaced from said second fluid volume into said reservoir, andwhereby said valve positioner is further displaceable from said first control position to a second control position wherein said second valve element is displaced from said port B1 opening said port B1 in fluid communication with said port A2 admitting fluid displaced from said second fluid volume into said first fluid volume, and said port B2 is blocked by said fourth valve element closing fluid communication between said port B2 and said port T2.