Hydraulic drive system
First Claim
1. A hydraulic drive system comprising an actuator having a pair of chambers separated by a drive member and disposed to apply a motive force in opposite directions to said drive member, each chamber being connected to a respective one of a pair of variable capacity machines, at least one of which is operable in a pumping mode to supply fluid to a chamber and at least the other of which is operable in a motoring mode to consume fluid expelled from the other of said chambers, each of said machines having a pressure compensating control to condition said machine to maintain a respective predetermined pressure in said chambers and an external control operable to modulate said predetermined pressure in at least one of said machines and thereby vary the motive forces acting on said drive member.
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Accused Products
Abstract
A hydraulic drive system for an actuator uses a pair of pressure compensated hydraulic machines to control flow to and from the drive chambers of the actuator by varying the controlled pressure of one of the machines. The machines are mechanically coupled to permit energy recovery and charge an accumulator to store supplies energy. The drive system may be combined with other services including a transmission for incorporation in a vehicle. The transmission uses a pressure compensated supply and torque control of the wheels.
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Citations
40 Claims
- 1. A hydraulic drive system comprising an actuator having a pair of chambers separated by a drive member and disposed to apply a motive force in opposite directions to said drive member, each chamber being connected to a respective one of a pair of variable capacity machines, at least one of which is operable in a pumping mode to supply fluid to a chamber and at least the other of which is operable in a motoring mode to consume fluid expelled from the other of said chambers, each of said machines having a pressure compensating control to condition said machine to maintain a respective predetermined pressure in said chambers and an external control operable to modulate said predetermined pressure in at least one of said machines and thereby vary the motive forces acting on said drive member.
- 33. A hydraulic transmission comprising a first variable capacity hydraulic machine to be driven by a prime mover, at least one variable capacity hydraulic drive unit, a hydraulic conduit connecting said first machine and said drive unit, a pressure compensating control operable on said first machine to vary the capacity thereof and maintain a predetermined pressure in said conduit and an external control operable upon said drive unit and vary the capacity thereof to vary the torque generated by said drive unit and wherein said first machine is mechanically connected to an additional variable capacity machine to supply fluid to an accumulator.
- 38. A hydraulic transmission comprising a first variable capacity hydraulic machine to be driven by a prime mover, at least one variable capacity hydraulic drive unit, a hydraulic conduit connecting said first machine and said drive unit, a pressure compensating control operable on said first machine to vary the capacity thereof and maintain a predetermined pressure in said conduit and an external control operable upon said drive unit and vary the capacity thereof to vary the torque generated by said one drive unit and wherein said first machine and said one drive unit are reversible and said external control is operable to vary the capacity of said one drive unit from a condition in which it consumes fluid in said conduit to a position in which it delivers fluid to said conduit, said pressure compensating control thereby causing said first machine to reverse the mode of operation to maintain said predetermined pressure.
Specification