Patent ID: 6116142
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 reservoir port (T1) coupled in fluid communication with said reservoir and couplable in fluid communication with said port A1, a second reservoir port (T2) coupled in fluid communication with said reservoir and couplable in fluid communication with said port B1, a first by-pass port (A2) coupled in fluid communication with said first fluid volume of said cylinder, and a second by-pass port (B2) coupled in fluid communication with said second fluid volume of said cylinder and couplable in fluid communication with said port A2; anda valve positioner having a plurality of valve elements including, in series, a first valve element, a second valve element having a first control edge and a spaced-apart second control edge, and a third 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 A2 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, and said third valve element is displaced from said port A2 opening said port A2 in fluid communication with said port B2 admitting fluid displaced from said second fluid volume into said first fluid volume, said first control edge of said second valve element being spaced-apart from said second control edge such that said port B1 remains blocked by said second valve element when said valve positioner is disposed in said first control position.