초록

A hydraulic energy storage system for vehicles to provide higher efficiency, smaller package size, lower weight, unitary construction, durability and enhanced reliability while maintaining the capability to efficiently store and restore energy at high power levels.

대표청구항 ▼

The invention claimed is: 1. A hydraulic energy storage system for use in a vehicle comprising a high pressure accumulator, a first low pressure accumulator and a second low pressure accumulator connected in parallel, a pump/motor in fluid communication with the high pressure accumulator and with t

The invention claimed is: 1. A hydraulic energy storage system for use in a vehicle comprising a high pressure accumulator, a first low pressure accumulator and a second low pressure accumulator connected in parallel, a pump/motor in fluid communication with the high pressure accumulator and with the first and second low pressure accumulators for pumping a fluid from the first and second low pressure accumulators to the high pressure accumulator when the pump/motor is driven in a pump mode and for returning fluid to the first and second low pressure accumulators when the pump/motor is in a motor mode, said pump/motor having a case for circulating fluid there through, a first check valve in series between the pump/motor and the second low pressure accumulator when the pump/motor is in the motor mode for unidirectional flow of a portion of fluid from the pump/motor to the second low pressure accumulator, a cooler in fluid communication in series between the case of the pump/motor, the second low pressure accumulator, and the pump/motor, and a second check valve in series between the second low pressure accumulator and the pump/motor case for unidirectional flow of fluid from the second low pressure accumulator through pump/motor case and the cooler to the pump/motor for cooling of said portion of the fluid when the pump/motor is in the pump mode. 2. A unitized accumulator system comprising the compensated accumulator as claimed in claim 1 in which the cylindrical housing is incorporated with a valve block and with an overcentre-type pump/motor or non-overcentre-type pump/motor for a unitary structure for direct mounting to a vehicle final drive. 3. A compensated accumulator for use in a hydraulic energy storage system for use in a vehicle comprising a cylindrical housing having a longitudinal axis and having a high pressure chamber and a low pressure chamber concentric with the longitudinal axis, a high pressure piston mounted transversely in the high pressure chamber for reciprocal axial travel in the high pressure chamber and a low pressure piston mounted transversely in the low pressure chamber for reciprocal axial travel in the low pressure chamber, and at least three equispaced rods connecting the high pressure piston to the low pressure piston for maintaining the pistons perpendicular to the longitudinal axis of the cylindrical housing during reciprocal travel. 4. A compensated accumulator as claimed in claim 3, having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, said low pressure piston having axial plunger extending therefrom, a surge reservoir for receiving fluid draining from a piston/motor, a cylindrical gallery formed in an end wall of the low pressure chamber for sealingly receiving the piston plunger and for receiving fluid from the surge reservoir for draining into the atmospheric chamber, and a fluid outlet in the bottom of the atmospheric chamber in communication with said low pressure accumulator or low pressure chamber through a check valve, whereby insertion of the piston plunger closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 5. A compensated accumulator as claimed in claim 3 having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, a surge reservoir for receiving fluid draining from a piston/motor, an opening formed in an end wall of the low pressure chamber for receiving fluid from the surge reservoir for draining into the atmospheric chamber, plunger means formed in the piston for closing said end wall opening, and a fluid outlet in the bottom of the atmospheric chamber in communication with said low pressure accumulator or chamber through a check valve, whereby reciprocal movement of the piston and plunger means closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 6. A compensated accumulator as claimed in claim 3 having an atmospheric chamber at the distal end of the low pressure chamber in which a spring return plunger pump is mounted in proximity to the top of the low pressure piston extending into the low pressure chamber for abutment with a barrier wall separating the low pressure chamber from the high pressure chamber, an inlet to the plunger pump from the low pressure chamber formed in the top of the low pressure piston, a normally-closed check valve in the inlet for undirectional flow from the low pressure chamber into the plunger pump and an outlet from the plunger pump to the atmospheric chamber, and a normally-closed check valve in the outlet for undirectional flow from the plunger pump to the atmospheric chamber, whereby abutment of the plunger pump against the barrier wall during reciprocal movement of the low pressure piston pumps any air present at the top of the low pressure chamber into the atmospheric chamber. 7. A compensated accumulator as claimed in claim 6 in which the plunger pump is mounted in the barrier wall and conduit means formed in the barrier wall direct pumped air to the atmosphere. 8. A compensated accumulator as claimed in claim 3 having an atmospheric chamber at the distal end of the low pressure chamber, in which the cylindrical housing has a barrier wall separating the high pressure chamber from the low pressure chamber, a poppet valve seated in a valve seat formed in the barrier wall and biased for normally-closed flow from the high pressure chamber to the low pressure chamber, said poppet valve having a stem projecting into the low pressure chamber, whereby abutment of the low pressure piston against the poppet stem opens the poppet valve to permit flow of high pressure fluid from the high pressure chamber into the low pressure chamber. 9. A compensated accumulator as claimed in claim 3 having an atmospheric chamber at the distal end of the low pressure chamber, in which the cylindrical housing has a barrier wall separating the high pressure compensated chamber from the low pressure chamber, a poppet thumb valve mounted on the high pressure piston projecting towards the barrier wall, a valve seat for the poppet thumb valve formed on the barrier wall in fluid communication with the low pressure chamber for receiving the poppet thumb valve for closure before complete discharge of high pressure fluid from the high pressure chamber, and a servo supply port formed in the barrier wall in fluid communication with the pump/motor, whereby residual high pressure fluid in the high pressure chamber after closure of the poppet thumb valve is directed to the motor pump. 10. A hydraulic energy storage system for use in a vehicle comprising a high pressure accumulator, a first low pressure accumulator and a second low pressure accumulator connected in parallel, a pump/motor in fluid communication with the high pressure accumulator and with the first and second low pressure accumulators for pumping a fluid from the first and second low pressure accumulators to the high pressure accumulator when the pump/motor is driven in a pump mode and for returning fluid to the first and second low pressure accumulators when the pump/motor is in a motor mode, said pump/motor having a case for circulating fluid therethrough, a first check valve in series between the pump/motor, the pump case and a cooler for unidirectional flow of a portion of fluid from the pump/motor through the pump case and the cooler and a second check valve in series with the cooler and the second low pressure accumulator for unidirectional flow of said portion of fluid from the cooler to the second low pressure accumulator for cooling said portion of fluid when the pump/motor is in the motor mode, a third check valve in series with the second low pressure accumulator and the pump/motor and a fourth check valve in series with the cooler and the first check valve for unidirectional flow of a portion of fluid from the second low pressure accumulator to the pump/motor case and through the cooler to the pump/motor for cooling said portion of the fluid when the pump/motor is in the pump mode. 11. A compensated accumulator for use in hydraulic energy storage system for use in a vehicle comprising a cylindrical housing having a longitudinal axis and having a high pressure chamber and a low pressure chamber concentric with the longitudinal axis, one of said high pressure chamber and said low pressure chamber having a larger diameter than the other, a high pressure piston slidably mounted for reciprocal travel in the high pressure chamber and a low pressure piston slidably mounted for reciprocal travel in the low pressure cylinder, one of said high pressure piston and low pressure piston having a larger diameter than the other for creating a flow imbalance between the high pressure cylinder and the low pressure cylinder, a pump/motor in fluid communication with the high pressure chamber and with the low pressure chamber for pumping a fluid from the low pressure chamber to the high pressure chamber when the pump/motor is driven in a pump mode and for returning fluid to the low pressure chamber when the pump/motor is in a motor mode, said pump/motor having a case for circulating fluid therethrough, a low pressure accumulator connected in parallel with the low pressure chamber for receiving and discharging a portion of fluid from the high pressure or low pressure chambers due to the flow imbalance between the high pressure cylinder and the low pressure cylinder, during the pump mode or the motor mode, a cooler in fluid communication with the pump/motor casing, a first check valve in series between the pump/motor, the pump case and the cooler for unidirectional flow of a portion of fluid from the pump/motor through the pump case and the cooler and a second check valve in series with the cooler and the low pressure accumulator for unidirectional flow of said portion of fluid from the cooler to the low pressure accumulator for cooling said portion of fluid when the pump/motor is in the motor mode, a third check valve in series with the low pressure accumulator and the pump/motor and a fourth check valve in series with the cooler and the first check valve for unidirectional flow of a portion of fluid from the low pressure accumulator to the pump/motor case and through the cooler to the pump/motor for cooling a portion of the fluid when the pump/motor is in the pump mode. 12. A compensated accumulator as claimed in claim 11 in which the high pressure piston is larger than the low pressure piston whereby outflow from the high pressure chamber is greater than the inflow to the low pressure chamber for maintaining a high fluid pressure and for creating positive flow imbalance from the high pressure cylinder to the low pressure cylinder. 13. A compensated accumulator as claimed in claim 12 in which the low pressure accumulator is an annular chamber formed concentric within the low pressure chamber, and comprising an annular accumulator piston slidably mounted for reciprocal travel in the annular accumulator chamber. 14. A compensated accumulator as claimed in claim 13 in which the annular accumulator piston is an elongated annular ring. 15. A compensated accumulator as claimed in claim 14 having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, said low pressure piston having axial plunger extending therefrom, a surge reservoir for receiving fluid draining from a piston/motor, a cylindrical gallery formed in an end wall of the low pressure chamber for sealingly receiving the piston plunger and for receiving fluid from the surge reservoir for draining into the atmospheric chamber, and a fluid outlet in the bottom of the atmospheric chamber in communication with a low pressure accumulator or low pressure chamber through a check valve, whereby insertion of the piston plunger closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 16. A compensated accumulator as claimed in claim 14 having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, a surge reservoir for receiving fluid draining from a piston/motor, an opening formed in an end wall of the low pressure chamber for receiving fluid from the surge reservoir for draining into the atmospheric chamber, plunger means formed in the piston for closing said end wall opening, and a fluid outlet in the bottom of the atmospheric chamber in communication with a low pressure accumulator or chamber through a check valve, whereby reciprocal movement of the piston and plunger means closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 17. A compensated accumulator as claimed in claim 14 having an atmospheric chamber at the distal end of the low pressure chamber in which a spring return plunger pump is mounted in proximity to the top of the low pressure piston extending into the low pressure chamber for abutment with a barrier wall separating the low pressure chamber from the high pressure chamber, an inlet to the plunger pump from the low pressure chamber formed in the top of the low pressure piston, a normally-closed check valve in the inlet for undirectional flow from the low pressure chamber into the plunger pump and an outlet from the plunger pump to the atmospheric chamber, and a normally-closed check valve in the outlet for undirectional flow from the plunger pump to the atmospheric chamber, whereby abutment of the plunger pump against the barrier wall during reciprocal movement of the low pressure piston pumps any air present at the top of the low pressure chamber into the atmospheric chamber. 18. A compensated accumulator as claimed in claim 14 having an atmospheric chamber at the distal end of the low pressure chamber, in which the cylindrical housing has a barrier wall separating the high pressure chamber from the low pressure chamber, a poppet valve seated in a valve seat formed in the barrier wall and biased for normally-closed flow from the high pressure chamber to the low pressure chamber, said poppet valve having a stem projecting into the low pressure chamber, whereby abutment of the low pressure piston against the poppet stem opens the poppet valve to permit flow of high pressure fluid from the high pressure chamber into the low pressure chamber. 19. A compensated accumulator as claimed in claim 14 having an atmospheric chamber at the distal end of the low pressure chamber, in which the cylindrical housing has barrier wall separating the high pressure compensated chamber from the low pressure chamber, a poppet thumb valve mounted on the high pressure piston projecting towards the barrier wall, a valve seat for the poppet thumb valve formed on the barrier wall in fluid communication with the low pressure chamber for receiving the poppet thumb valve for closure before complete discharge of high pressure fluid from the high pressure chamber, and a servo supply port formed in the barrier wall in fluid communication with the pump/motor, whereby residual high pressure fluid in the high pressure chamber after closure of the poppet thumb valve is directed to the motor pump. 20. A compensated accumulator for use in a hydraulic energy storage system for use in a vehicle comprising a cylindrical housing having a longitudinal axis with a high pressure chamber and a low pressure chamber concentric with the longitudinal axis, said low pressure chamber having a gas end remote from the high pressure chamber and a fluid end adjacent the high pressure chamber, a high pressure piston slidably mounted for reciprocal axial travel in the high pressure chamber and a low pressure piston mounted for reciprocal axial travel in the low pressure chamber, at least one connecting rod for connecting the high pressure piston and the low pressure piston together, a first position sensor mounted in the low pressure chamber adjacent the low pressure end and a second position sensor mounted in the low pressure chamber adjacent the high pressure end, whereby the first and second position sensors control reciprocal travel of the low pressure piston in the low pressure chamber, and a pressure sensor in fluid communication with the high pressure fluid chamber whereby the second position sensor or the pressure sensor controls reciprocal travel of the high pressure and low pressure pistons and actuates a heating system. 21. A compensated accumulator as claimed in claim 20 in which gas end has an end wall and in which the first position sensor is mounted in said end wall. 22. A compensated accumulator as claimed in claim 21 in which the first position sensor is mounted in the end wall on the longitudinal axis and comprises an ultrasonic transducer. 23. A compensated accumulator as claimed in claim 20 having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, said low pressure piston having axial plunger extending therefrom, a surge reservoir for receiving fluid draining from a piston/motor, a cylindrical gallery formed in an end wall of the low pressure chamber for sealingly receiving the piston plunger and for receiving fluid from the surge reservoir for draining into the atmospheric chamber, and a fluid outlet in the bottom of the atmospheric chamber in communication with said low pressure accumulator or low pressure chamber through a check valve, whereby insertion of the piston plunger closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 24. A compensated accumulator as claimed in claim 20 having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, a surge reservoir for receiving fluid draining from a piston/motor, an opening formed in an end wall of the low pressure chamber for receiving fluid from the surge reservoir for draining into the atmospheric chamber, plunger means formed in the piston for closing said end wall opening, and a fluid outlet in the bottom of the atmospheric chamber in communication with a low pressure accumulator or chamber through a check valve, whereby reciprocal movement of the piston and plunger means closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 25. A compensated accumulator as claimed in claim 20 having an atmospheric chamber at the distal end of the low pressure chamber in which a spring return plunger pump is mounted in proximity to the top of the low pressure piston extending into the low pressure chamber for abutment with a barrier wall separating the low pressure chamber from the high pressure chamber, an inlet to the plunger pump from the low pressure chamber formed in the top of the low pressure piston, a normally-closed check valve in the inlet for undirectional flow from the low pressure chamber into the plunger pump and an outlet from the plunger pump to the atmospheric chamber, and a normally-closed check valve in the outlet for undirectional flow from the plunger pump to the atmospheric chamber, whereby abutment of the plunger pump against the barrier wall during reciprocal movement of the low pressure piston pumps any air present at the top of the low pressure chamber into the atmospheric chamber. 26. A compensated accumulator as claimed in claim 20 having an atmospheric chamber at the distal end of the low pressure chamber, in which the cylindrical housing has a barrier wall separating the high pressure chamber from the low pressure chamber, a poppet valve seated in a valve seat formed in the barrier wall and biased for normally-closed flow from the high pressure chamber to the low pressure chamber, said poppet valve having a stem projecting into the low pressure chamber, whereby abutment of the low pressure piston against the poppet stem opens the poppet valve to permit flow of high pressure fluid from the high pressure chamber into the low pressure chamber. 27. A compensated accumulator as claimed in claim 20 having an atmospheric chamber at the distal end of the low pressure chamber, in which the cylindrical housing has a barrier wall separating the high pressure compensated chamber from the low pressure chamber, a poppet thumb valve mounted on the high pressure piston projecting towards the barrier wall, a valve seat for the poppet thumb valve formed on the barrier wall in fluid communication with the low pressure chamber for receiving the poppet thumb valve for closure before complete discharge of high pressure fluid from the high pressure chamber, and a servo supply port formed in the barrier wall in fluid communication with a pump/motor, whereby residual high pressure fluid in the high pressure chamber after closure of the poppet thumb valve is directed to the motor pump. 28. A compensated accumulator for use in a hydraulic energy storage system for use in a vehicle comprising a cylindrical housing having a longitudinal axis and having a high pressure chamber and low pressure chamber concentric with said longitudinal axis, each said high pressure chamber and said low pressure chamber having a gas end remote from each other and a fluid end adjacent each other, a high pressure piston slidably mounted for reciprocal axial travel in the high pressure chamber and a low pressure piston slidably mounted for reciprocal axial travel in the low pressure chamber, at least one connecting rod for connecting the high pressure and low pressure pistons together in axial alignment, a valve block at one end of the cylindrical housing, and a high pressure conduit communicating the high pressure fluid end to the valve block and a low pressure conduit communicating the low pressure fluid end to the valve block, and in which the high pressure and low pressure conduits are internal of the cylindrical housing disposed parallel to the longitudinal axis and pass through the low pressure piston, additionally comprising sealing means formed in the low pressure piston for slidably engaging and sealing the high pressure and low pressure conduits. 29. A compensated accumulator as claimed in claim 28 having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, said low pressure piston having axial plunger extending therefrom, a surge reservoir for receiving fluid draining from a piston/motor, a cylindrical gallery formed in an end wall of the low pressure chamber for sealingly receiving the piston plunger and for receiving fluid from the surge reservoir for draining into the atmospheric chamber, and a fluid outlet in the bottom of the atmospheric chamber in communication with a low pressure accumulator or low pressure chamber through a check valve, whereby insertion of the piston plunger closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 30. A compensated accumulator as claimed in claim 28 having an atmospheric chamber at the distal end of the low pressure chamber in which the low pressure piston reciprocates, a surge reservoir for receiving fluid draining from a piston/motor, an opening formed in an end wall of the low pressure chamber for receiving fluid from the surge reservoir for draining into the atmospheric chamber, plunger means formed in the piston for closing said end wall opening, and a fluid outlet in the bottom of the atmospheric chamber in communication with a low pressure accumulator or chamber through a check valve, whereby reciprocal movement of the piston and plunger means closes the atmospheric chamber to the atmosphere and compression of air in the atmospheric chamber opens the check valve to pump fluid in the bottom of the atmospheric chamber to the low pressure accumulator or low pressure chamber. 31. A compensated accumulator as claimed in claim 28 having an atmospheric chamber at the distal end of the low pressure chamber in which a spring return plunger pump is mounted in proximity to the top of the low pressure piston extending into the low pressure chamber for abutment with a barrier wall separating the low pressure chamber from the high pressure chamber, an inlet to the plunger pump from the low pressure chamber formed in the top of the low pressure piston, a normally-closed check valve in the inlet for undirectional flow from the low pressure chamber into the plunger pump and an outlet from the plunger pump to the atmospheric chamber, and a normally-closed check valve in the outlet for undirectional flow from the plunger pump to the atmospheric chamber, whereby abutment of the plunger pump against the barrier wall during reciprocal movement of the low pressure piston pumps any air present at the top of the low pressure chamber into the atmospheric chamber. 32. A compensated accumulator as claimed in claim 28 a having an atmospheric chamber at the distal end of the low pressure chamber, in which the cylindrical housing has a barrier wall separating the high pressure compensated chamber from the low pressure chamber, a poppet thumb valve mounted on the high pressure piston projecting towards the barrier wall, a valve seat for the poppet thumb valve formed on the barrier wall in fluid communication with the low pressure chamber for receiving the poppet thumb valve for closure before complete discharge of high pressure fluid from the high pressure chamber, and a servo supply port formed in the barrier wall in fluid communication with a pump/motor, whereby residual high pressure fluid in the high pressure chamber after closure of the poppet thumb valve is directed to the motor pump. 33. A compensated accumulator for use in a hydraulic energy storage system for use in a vehicle comprising a cylindrical housing having a longitudinal axis and having a high pressure chamber and a low pressure chamber concentric with the longitudinal axis, a high pressure piston mounted transversely in the high pressure chamber for reciprocal axial travel in the high pressure chamber and a low pressure annular piston mounted transversely in the low pressure chamber for reciprocal travel in the low pressure chamber, at least three equispaced rods connecting the high pressure piston to the low pressure piston for maintaining the pistons perpendicular to the longitudinal axis of the cylindrical housing during reciprocal travel, a low pressure accumulator cylinder formed centrally in the low pressure chamber concentric with and within the low pressure annular piston, sealing means formed between the low pressure accumulator cylinder and the annular piston whereby the annular piston is in sliding engagement with the low pressure accumulator piston, a pump/motor in fluid communication with the high pressure chamber and with the low pressure chamber and the low pressure accumulator for pumping a fluid from the low pressure chamber and from the low pressure accumulator to the high pressure chamber when the pump/motor is in a pump mode and for returning fluid to the low pressure chamber and to the low pressure accumulator from the high pressure chamber when the pump/motor is in a motor mode, said pump/motor having a case for circulating fluid therethrough, a cooler in fluid communication with the pump/motor casing and the low pressure accumulator whereby the fluid flowing to and from the low pressure accumulator flows through the cooler when the pump/motor is in the pump and motor modes. 34. A compensated accumulator as claimed in claim 33 in which the low pressure accumulator cylinder has an access port formed in an upper portion thereof for venting air to the atmosphere. 35. A compensated accumulator as claimed in claim 34 in which the high pressure chamber has a steel liner for reciprocal axial travel of the high pressure piston therein, said steel liner defining an annulus between the steel liner and the cylinder substantially the length of the piston stroke, and fluid conduit means interconnecting said annulus with fluid in the high pressure chamber for equalizing hydraulic pressure between the liner and the chamber. 36. A compensated accumulator as claimed in claim 35 in which the liner extends substantially the length of the high pressure chamber.