Hydraulic Drive System
First Claim
1. A hydraulic transmission comprising a first rotary hydraulic machine to be driven by a prime mover, at least one hydraulic drive unit, a hydraulic conduit connecting said first machine and said drive unit, a control operable to control delivery of fluid between said first rotary machine and said drive unit, an additional variable capacity machine mechanically connected to said first machine to supply fluid to an accumulator and a sensor to monitor rotational speed of said first machine, said control operable top vary the capacity of said additional machine and thereby maintain said rotational speed at a desired level.
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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
16 Claims
- 1. A hydraulic transmission comprising a first rotary hydraulic machine to be driven by a prime mover, at least one hydraulic drive unit, a hydraulic conduit connecting said first machine and said drive unit, a control operable to control delivery of fluid between said first rotary machine and said drive unit, an additional variable capacity machine mechanically connected to said first machine to supply fluid to an accumulator and a sensor to monitor rotational speed of said first machine, said control operable top vary the capacity of said additional machine and thereby maintain said rotational speed at a desired level.
- 8. A method of operating a hydraulic transmission having a first rotary hydraulic machine to be driven by a prime mover, at least one hydraulic drive unit, a hydraulic conduit connecting said first machine and said drive unit, a control operable to control delivery of fluid between said first rotary machine and said drive unit, an additional variable capacity machine mechanically connected to said first machine to supply fluid to an accumulator and a sensor to monitor rotational speed of said first machine, said method comprising the steps of monitoring said speed of rotation and varying the capacity of said additional machine to maintain said speed at said desired level.
- 13. A hydraulic transmission for a vehicle having a pair of drive members to propel the vehicle, said transmission comprising a first variable capacity reversible hydraulic machine to be driven by a prime mover, a plurality of variable capacity reversible hydraulic drive units, each associated with a respective one of the drive members, a hydraulic conduit connecting said first machine and said drive units, 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 units and vary the capacity thereof to vary the torque generated by respective ones of said drive units and a sensor associated with each of said drive members to determine the rotational speed thereof, said external control being operable to vary the capacity of respective ones of said drive units and change between a driving condition in which said drive unit consumes fluid in said conduit and a braking condition in which it delivers fluid to said conduit, and said pressure compensating control being operable to cause said first machine to reverse the mode of operation to maintain said predetermined pressure in said conduit, said control monitoring the relative speeds of rotation of said drive members and adjusting the capacity of said drive units to maintain a predetermined relationship therebetween.
Specification