Pump-motor power limiter and pressure relief
OwnerWillie B. Leonardinventor
Life of this patent
Estimating the term…
Abstract
Pump-motor hydraulic power system incorporation means to limit the power transmitted and the pressure in the transmission lines. High pressure line is connected to one end of a servo motor comprising a cylinder with a spring loaded piston therein. When the pump pressure increases above a certain amount it overcomes the spring and moves the piston and the piston rod to a blocking position, acting to limit movement of the three way control valve or to move the three way control valve back if it already exceeds the limit imposed by the power limiter's piston rod.
Claims20
In combination with a pump-motor hydraulic power transmission system including a pump, a motor, and two hydraulic fluid transmission lines interconnecting the pump and motor, at least one of said pump and motor having a variable angle swash-plate,
- servo motor means to vary the angle of said swash plate,
- control valve means for controlling the servo means, said control valve means including a three-way valve for alternate connection of one side of said servo-motor means to a source of fluid pressure and a reservoir, and
- operator means for positioning the control valve means;
- travel limit means at each opposite end of said three-way valve positionable in the path of travel of said three-way valve for abutment therewith and
- motor means associated with each respective travel limit means and responsive to the pressure in the higher pressure one of said transmission lines to adjust the position of a said respective travel limit means,
- a spring means biasing each of said motor means to a position where said travel limit means is disengaged from said three-way valve,
- said travel limit means being movable between
- (1) a normal position disengaged from said three-way valve,
- (2) positions in the path of travel of said three-way valve but out of contact therewith, and
- (3) positions in abutting engagement with said three-way valve and determining the position of the three-way valve.
In combination with a pump-motor hydraulic power transmission system including a pump, a motor, and two hydraulic fluid transmission lines interconnecting the pump and motor, at least one of said pump and motor having a variable angle swash-plate,
- servo motor means to vary the angle of said swash plate,
- control valve means for controlling the servo motor means, said control valve means including a three-way valve for alternate connection of one side of said servo motor means to a source of fluid pressure and a reservoir and
- operator means for positioning the control valve means;
- a power limit means for restricting the power transmitted from the pump to the motor comprising:
- travel limit means at each end of said three-way valve that is adjustably positionable for limiting the travel of said three-way valve by abutment therewith, and
- motor means at each opposite end and associated with a respective travel limit means, said motor means being responsive to the pressure in the higher pressured one of said transmission lines to adjust the position of said travel limit means,
- said motor means including
- a cylinder, and
- a piston movable in the cylinder,
- said travel limit means being connected to said piston,
- said one transmission line being connected to said cylinder at one side of said piston to create a fluid pressure thereon urging the piston in a direction to place said travel limit means in a position to limit control valve movement, and
- spring means urging said piston in the opposite direction from said fluid pressure disengaging said travel limit means from said three-way valve,
- said three-way valve including a seat member having openings for passage of fluid between said servo motor and said source and reservoir and a closure member for controlling flow through said openings,
- said operator means and said travel limit means both being associated with the same one of said members, and
- feedback means connecting the swash plate to the other of said members.
In combination with a pump-motor hydraulic power transmission system including a pump, a motor, and two hydraulic fluid transmission lines interconnecting the pump and motor, at least one of said pump and motor having a variable angle swash-plate, servo motor means to vary the angle of said swash plate, control valve means for controlling the servo motor means, said control valve means including a three way valve for alternate connection of one side of said servo motor means to a source of fluid pressure and a reservoir and operator means for positioning the control valve means;
- a power limit means for restricting the power transmitted from the pump to the motor comprising:
- travel limit means that is adjustably positionable for limiting the travel of said three-way valve by abutment therewith and
- motor means responsive to the pressure in the high pressured one of said transmission lines to adjust the position of said travel limit means,
- said motor means including
- a cylinder, and
- a piston movable in the cylinder,
- said travel limit means being connected to said piston,
- said one transmission line being connected to said cylinder at one side of said piston to create a fluid pressure thereon urging the piston in a direction to place said travel limit means in a position to limit control valve movement, and
- springs means urging said piston in the opposite direction from said fluid pressure disengaging said travel limit means from said three-way valve,
- said motor means further including
- a pressure relief valve means connected to said cylinder on the spring side of said piston,
- a restricted flow passage from said spring side of the piston to the other side thereof,
- said restricted flow passage having a higher resistance to fluid flow from said other side of said piston to said spring side of said piston than the resistance for flow from said spring side of said piston through said pressure relief valve when the latter is open.
In combination with a pump-motor hydraulic system including a pump, a motor, and two hydraulic fluid transmission lines interconnecting the pump and motor, at least one of said pump and motor having a variable angle swash-plate, servo motor means to vary the angle of said swash plate, control valve means for including a three-way valve for alternate connection of one side of said servo motor means to a source of fluid pressure and a reservoir and operator means for positioning the control valve means;
- a power limit means for restricting the power transmitted from the pump to the motor comprising:
- travel limit means that is adjustably positionable for limiting the travel of said three-way valve by abutment therewith and
- motor means responsive to the pressure in the higher pressured one of said transmission lines to adjust the position of said travel limit means,
- said travel limit means including a first stop means disengaged from said three-way valve when the pressure in one of said lines is below a set value for limiting travel of the three-way valve in one direction and a second stop means disengaged from said three-way valve when the pressure in the other of said lines is below a set value for limiting travel of the three-way valve in the opposite direction,
- said motor means including a first motive means responsive to the pressure in one of said transmission lines and biased by a first spring means disengaging said first stop means from said three-way valve to adjust the position of the first stop means and a second motive means responsive to the pressure in the other of said transmission lines and biased by a second spring means disengaging said second spring stop means from said three-way valve to adjust the position of the second stop means.
In combination with a pump-motor hydrualic power transmission system including a pump, a motor, and two hydraulic fluid transmission lines interconnecting the pump and motor, at least one of said pump and motor having a variable angle swash-plate,
- servo motor means to vary the angle of said swash plate,
- control valve means for controlling the servo motor means, said control valve means including a three way valve for alternate connection of one side of said servo motor means to a source of fluid pressure and a reservoir, and
- operator means for positioning the control valve means;
- a power limit means for restricting the power transmitted from the pump to the motor comprising:
- travel limit means at each opposite end of said three-way valve that is adjustably positionable for limiting the travel of said three-way valve by abutment therewith, and
- motor means at each said opposite end and associated with a respective travel limit means, each said motor means being biased by a spring out of engagement with said three-way valve and being responsive to the pressure in the higher pressured one of said transmission lines to adjust the position of said travel limit means,
- said operator means including
- a fluid transmission conduit means,
- means to supply pressure fluid to said conduit means,
- transmitter means to variably vent said conduit means, and
- responder means responsive to changes in pressure of said conduit means to move a portion of the responder means, said portion being connected to said three way valve,
- said travel means being associated with the same movable part of said three way valve means as said responder means and overriding said responder means in determining the position of said three way valve.
In combination with a pump-motor hydraulic power transmission system including a pump, a motor, and two hydraulic fluid transmission lines interconnecting the pump and motor having a variable angle swash-plate,
- servo motor means to vary the angle of said swash plate,
- control valve means for controlling the servo motor means, said control valve means including a three-way valve for alternate connection of one side of said servo motor means to a source of fluid pressure and a reservoir and
- operator means for positioning the control valve means;
- a power limit means for restricting the power transmitted from the pump to the motor comprising:
- travel limit means at at least one end of said three-way valve that is adjustably positionable for limiting the travel of said three-way valve by abutment therewith and
- motor means at said at least one end of said three-way valve and associated with said travel limit means, said motor means being biased by a spring out of engagement with said three-way valve and being responsive to the pressure in one of said transmission lines to adjust the position of said travel limit means,
- said operator means including:
- a fluid transmission conduit means,
- means to supply pressure fluid to said conduit means,
- transmitter means to variably vent said conduit means, and
- responder means responsive to changes in pressure of said conduit means to move a portion of the responder means, said portion being connected to said three-way valve,
- said travel limit means being connected to the same movable part of said three-way valve means as said responder means and overriding said responder means in determining the position of said three-way valve,
- said travel limit means being movable between
- (1) a normal position disengaged from said three-way valve,
- (2) positions in the path of travel of said three-way valve but out of contact therewith, and
- (3) positions in abutting engagement with said three-way valve and determining the position of the three-way valve.
Dependencies are inferred from the claim text.