Patent ID: 6129001
Filing Date: 2000-10-10
Classification: F15B

Abstract:
A method of controlling the function of a reciprocatable power machine having a reciprocatable piston located between first and second pressure chambers, said method comprising the steps of:moving the piston in an active power stroke from an end of a then active first pressure chamber to an end of a then inactive second pressure chamber by supplying a pressure fluid at a full power pressure to the then active first pressure chamber;building up a stopping counter pressure in the then inactive second pressure chamber as the piston approaches the end of the then inactive second pressure chamber to counter-act the full power pressure of the pressure fluid in the then active first pressure chamber;decreasing of the stopping counter pressure in the then inactive second pressure chamber to a positive final stopping counter pressure as the piston reaches the end of the then inactive second pressure chamber so that the piston is softly stopped at the end of the then inactive second pressure chamber against the final stopping counter pressure;utilizing the final stopping counter pressure to start an active return power stroke of the piston from the end of a then active second pressure chamber;supplying the pressure fluid at a full power pressure to the then active second pressure chamber after said utilizing step to move the piston in said active return power stroke from an end of the then active second pressure chamber to an end of a then inactive first pressure chamber;providing a starting counter pressure in the then inactive first pressure chamber as the piston starts to move from the end of the then active second pressure chamber to counter-act the full power pressure of the pressure fluid in the then active second pressure chamber, said providing a starting counter pressure step including the steps ofthe controlled opening of the then active first pressure chamber to ambient to fully vent the full power pressure of the pressure fluid as the piston approaches the end of the then inactive second pressure chamber, andthe closing of the then inactive first pressure chamber to ambient as the full power pressure fluid is supplied to the then active second pressure chamber and the piston starts to move; anddecreasing of the starting counter pressure in the then inactive first pressure chamber as the piston leaves the end of the then active second pressure chamber so that the piston is softly started at the end of the then active second pressure chamber, wherein said decreasing of the starting counter pressure step includes the step of venting the counter pressure in the then inactive first pressure chamber to ambient.