Assistive torque electro-hydraulic piston pump system

Abstract

An electro-hydraulic piston pump system comprising an electric motor (16), first and second hydraulic piston pumps (30,60), a first hydraulic actuator (90) having a first port (93) connected directly to a first port (48) of the first pump and a second port (94) connected directly to a second port (49) of the first pump, a second hydraulic actuator (100) having a third port (103) connected directly to a third port (78) of the second pump and a fourth port (104) connected directly to a fourth port (79) of the second piston pump, wherein an external force applied to the first hydraulic actuator (90) that provides a negative pressure differential to the first pump applies an assistive torque to a common motor shaft (18) driving both the first pump (30) and the second pump (60), and an external force applied to the first and second actuators (90,100) that provides a summed negative pressure differential to the first and second pumps (30,60) recharges a power supply for the motor (16).

1 . An electro-hydraulic pump system comprising:
 an electric motor adapted to be supplied with a current and having a drive shaft;   a first hydraulic piston pump comprising a first fluid control journal, a plurality of pistons in a first cylinder block adapted to rotate relative to said first fluid control journal about a first block axis with rotation of said drive shaft, and a first displacement drive having a first displacement axis;   said first displacement drive adapted to move in a first positive displacement range between a first neutral position between said first displacement axis and said first block axis and a first maximum positive displacement position between said first displacement axis and said first block axis;   said first displacement drive adapted to move in a first negative displacement range between said first neutral position and a first maximum negative displacement position between said first displacement axis and said first block axis;   said first fluid control journal comprising a first pump port and a second pump port, wherein rotation of said drive shaft when said first displacement drive is in said first positive displacement range provides higher pressure to said first pump port relative to said second pump port, and wherein rotation of said drive shaft when said first displacement drive is in said first negative displacement range provides higher pressure to said second pump port relative to said first pump port;   a second hydraulic piston pump comprising a second fluid control journal, a plurality of pistons in a second cylinder block adapted to rotate relative to said second fluid control journal about a second block axis with rotation of said drive shaft, and a second displacement drive having a second displacement axis;   said second displacement drive adapted to move in a second positive displacement range between a second neutral position between said second displacement axis and said second block axis and a second maximum positive displacement position between said second displacement axis and said second block axis;   said second displacement drive adapted to move in a second negative displacement range between said second neutral position between said second displacement axis and said second block axis and a second maximum negative displacement position between said second displacement axis and said second block axis;   said second fluid control journal comprising a third pump port and a fourth pump port, wherein rotation of said drive shaft when said second displacement drive is in said second positive displacement range provides higher pressure to said third pump port relative to said fourth pump port, and wherein rotation of said drive shaft when said second displacement drive is in said second negative displacement range provides higher pressure to said fourth pump port relative to said third pump port;   a first hydraulic actuator having a first working port hydraulically connected to said first pump port of said first piston pump;   said first hydraulic actuator having a second working port hydraulically connected to said second pump port of said first piston pump;   a second hydraulic actuator having a third working port hydraulically connected to said third pump port of said second piston pump;   said second hydraulic actuator having a fourth working port hydraulically connected to said fourth pump port of said second piston pump;   wherein an external force applied to said first hydraulic actuator that provides higher pressure to said second pump port relative to said first pump port when said first displacement drive is in said first positive displacement range applies an assistive torque to said drive shaft; and   wherein an external force applied to said first hydraulic actuator that provides higher pressure to said first pump port relative to said second pump port when said first displacement drive is in said first negative displacement range applies an assistive torque to said drive shaft.   
     
     
         2 . The electro-hydraulic pump system set forth in  claim 1 , wherein:
 an external force applied to said second hydraulic actuator that provides higher pressure to said fourth pump port relative to said third pump port when said second displacement drive is in said second positive displacement range applies an assistive torque to said drive shaft; and   an external force applied to said second hydraulic actuator that provides higher pressure to said third pump port relative to said fourth pump port when said second displacement drive is in said second negative displacement range applies an assistive torque to said drive shaft.   
     
     
         3 . (canceled) 
     
     
         4 . The electro-hydraulic pump system set forth in  claim 1 , comprising a battery supplying said current to said electric motor and wherein said motor is configured to selectively supply a current to said battery in a regeneration mode when:
 an external force applied to said first hydraulic actuator provides higher pressure to said second pump port relative to said first pump port when said first displacement drive is in said first positive displacement range or an external force applied to said first hydraulic actuator provides higher pressure to said first pump port relative to said second pump port when said first displacement drive is in said first negative displacement range; and   an external force applied to said second hydraulic actuator provides higher pressure to said fourth pump port relative to said third pump port when said second displacement drive is in said second positive displacement range or an external force applied to said second hydraulic actuator provides higher pressure to said third pump port relative to said fourth pump port when said second displacement drive is in said second negative displacement range.   
     
     
         5 . The electro-hydraulic pump system set forth in  claim 1 , wherein said first hydraulic actuator is configured to actuate a first object of an electrically powered vehicle, said second hydraulic actuator is configured to actuate a second object of said electrically powered vehicle, and said electric motor is selected from a group consisting of a brushless DC servo-motor, a stepper motor, a brush motor and an induction motor. 
     
     
         6 . (canceled) 
     
     
         7 . The electro-hydraulic pump system set forth in  claim 1 , wherein said first hydraulic actuator comprises a linear hydraulic actuator or a rotary hydraulic actuator. 
     
     
         8 . The electro-hydraulic pump system set forth in  claim 7 , wherein:
 said first hydraulic actuator comprises a linear hydraulic actuator having a first chamber, a second chamber and a piston separating said first and second chambers;   said first hydraulic actuator comprises a cylinder having a first end wall, said piston is disposed in said cylinder for sealed sliding movement therein, and said piston comprises a first actuator rod having a portion sealingly penetrating said first end wall; and   said cylinder has a second end wall and said piston comprises a second actuator rod having a portion sealingly penetrating said second end wall.   
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . The electro-hydraulic pump system set forth in  claim 8 , comprising at least one of a position sensor configured to sense the position of said piston and a pressure sensor configured to sense pressure in said first and second chambers. 
     
     
         12 . (canceled) 
     
     
         13 . The electro-hydraulic pump system set forth in  claim 1 , comprising:
 a third hydraulic piston pump comprising a third fluid control journal, a plurality of pistons in a third cylinder block adapted to rotate relative to said third fluid control journal about a third block axis with rotation of said drive shaft, and a third displacement drive having a third displacement axis;   said third displacement drive adapted to move in a third positive displacement range between a third neutral position between said third displacement axis and said third block axis and a third maximum positive displacement position between said third displacement axis and said third block axis;   said third displacement drive adapted to move in a third negative displacement range between said third neutral position between said third displacement axis and said third block axis and a third maximum negative displacement position between said third displacement axis and said third block axis;   said third fluid control journal comprising a fifth pump port and a sixth pump port, wherein rotation of said drive shaft when said third displacement drive is in said third positive displacement range provides higher pressure to said fifth pump port relative to said sixth pump port, and wherein rotation of said drive shaft when said third displacement drive is in said third negative displacement range provides higher pressure to said sixth pump port relative to said fifth pump port;   a third hydraulic actuator having a fifth working port hydraulically connected to said fifth pump port of said third piston pump;   said third hydraulic actuator having a sixth working port hydraulically connected to said sixth pump port of said third piston pump;   wherein an external force applied to said third hydraulic actuator that provides higher pressure to said sixth pump port relative to said fifth pump port when said third displacement drive is in said third positive displacement range applies an assistive torque to said drive shaft; and   an external force applied to said third hydraulic actuator that provides higher pressure to said fifth pump port relative to said sixth pump port when said third displacement drive is in said third negative displacement range applies an assistive torque to said drive shaft.   
     
     
         14 . The electro-hydraulic pump system set forth in  claim 13 , wherein said shaft comprises a first portion connected to said first cylinder block, a second portion connected to said second cylinder block, and a third portion connected to said third cylinder block. 
     
     
         15 . The electro-hydraulic pump system set forth in  claim 1 , comprising:
 a first displacement drive actuator connected to said first displacement drive and configured to selectively move said first displacement drive in said first positive displacement range and to selectively move said first displacement drive in said first negative displacement range; and   a second displacement drive actuator connected to said second displacement drive and configured to selectively move said second displacement drive in said second positive displacement range and to selectively move said second displacement drive in said second negative displacement range.   
     
     
         16 . (canceled) 
     
     
         17 . The electro-hydraulic pump system set forth in  claim 1 , wherein:
 said first fluid control journal comprises a first central control journal;   said first displacement drive comprises a first stroke ring orientated about said first displacement axis;   said first neutral position between said first displacement axis and said first block axis comprises a position in which said first displacement axis and said first block axis are coaxial;   said first stroke ring is adapted to move radially relative to said first neutral position;   said first maximum positive displacement position between said first displacement axis and said first block axis comprises a first positive eccentric position wherein said first displacement axis is offset from said first block axis in a first positive direction relative said first neutral position a first positive maximum eccentric distance;   said first positive displacement range comprises a first positive eccentric range between said first neutral position and a first positive eccentric position;   said first maximum negative displacement position between said first displacement axis and said first block axis comprises a first negative eccentric position wherein said first displacement axis is offset from said first block axis in a first negative direction relative said first neutral position a first negative maximum eccentric distance;   said first negative displacement range comprises a first negative eccentric range between said first neutral position and a first negative eccentric position;   rotation of said drive shaft when said first stroke ring is in said first positive eccentric range provides higher pressure to said first pump port relative to said second pump port, and rotation of said drive shaft when said first stroke ring is in said first negative eccentric range provides higher pressure to said second pump port relative to said first pump port;   said second fluid control journal comprises a second central control journal;   said second displacement drive comprises a second stroke ring orientated about said second displacement axis;   said second neutral position between said second displacement axis and said second block axis comprises a position in which said second displacement axis and said second block axis are coaxial;   said second stroke ring is adapted to move radially relative to said second neutral position;   said second maximum positive displacement position between said second displacement axis and said second block axis comprises a second positive eccentric position wherein said second displacement axis is offset from said second block axis in a second positive direction relative said second neutral position a second positive maximum eccentric distance;   said second positive displacement range comprises a second positive eccentric range between said second neutral position and a second positive eccentric position;   said second maximum negative displacement position between said second displacement axis and said second block axis comprises a second negative eccentric position wherein said second displacement axis is offset from said second block axis in a second negative direction relative said second neutral position a second negative maximum eccentric distance;   said second negative displacement range comprises a second negative eccentric range between said second neutral position and a second negative eccentric position;   rotation of said drive shaft when said second stroke ring is in said second positive eccentric range provides higher pressure to said third pump port relative to said fourth pump port, and rotation of said drive shaft when said second stroke ring is in said second negative eccentric range provides higher pressure to said fourth pump port relative to said third pump port;   an external force applied to said first hydraulic actuator that provides higher pressure to said second pump port relative to said first pump port when said first stroke ring is in said first positive eccentric range applies an assistive torque to said drive shaft; and   an external force applied to said first hydraulic actuator that provides higher pressure to said first pump port relative to said second pump port when said first stroke ring is in said first negative eccentric range applies an assistive torque to said drive shaft.   
     
     
         18 . The electro-hydraulic pump system set forth in  claim 17 , wherein:
 an external force applied to said second hydraulic actuator that provides higher pressure to said fourth pump port relative to said third pump port when said second stroke ring is in said second positive eccentric range applies an assistive torque to said drive shaft; and   an external force applied to said second hydraulic actuator that provides higher pressure to said third pump port relative to said fourth pump port when said second stroke ring is in said second negative eccentric range applies an assistive torque to said drive shaft.   
     
     
         19 . The electro-hydraulic pump system set forth in  claim 17 , comprising a battery supplying said current to said electric motor and wherein said motor is configured to selectively supply a current to said battery in a regeneration mode when:
 an external force applied to said first hydraulic actuator provides higher pressure to said second pump port relative to said first pump port when said first stroke ring is in said first positive eccentric range or an external force applied to said first hydraulic actuator provides higher pressure to said first pump port relative to said second pump port when said first stroke ring is in said first negative eccentric range; and   an external force applied to said second hydraulic actuator provides higher pressure to said fourth pump port relative to said third pump port when said second stroke ring is in said second positive eccentric range or an external force applied to said second hydraulic actuator provides higher pressure to said third pump port relative to said fourth pump port when said second stroke ring is in said second negative eccentric range.   
     
     
         20 . The electro-hydraulic pump system set forth in  claim 17 , comprising:
 a third hydraulic piston pump comprising a third central control journal, a plurality of pistons in a third cylinder block adapted to rotate relative to said third central control journal about a third block axis with rotation of said drive shaft, and a third stroke ring orientated about a third atroke axis and adapted to move radially relative to a third neutral position in which said third stroke axis and said third block axis are coaxial;   said third stroke ring adapted to move linearly in a third positive eccentric range between said third neutral position and a third positive eccentric position, wherein said third stroke axis is offset from said third block axis in a third positive direction relative said third neutral position a third positive maximum eccentric distance;   said third stroke ring adapted to move linearly in a third negative eccentric range between said third neutral position and a third negative eccentric position, wherein said third stroke axis is offset from said third block axis in a third negative direction opposite to said third positive direction relative to said third neutral position a third negative maximum eccentric distance;   said third control journal comprising a fifth pump port and a sixth pump port, wherein rotation of said drive shaft when said third stroke ring is in said third positive eccentric range provides higher pressure to said fifth pump port relative to said sixth pump port, and wherein rotation of said drive shaft when said third stroke ring is in said third negative eccentric range provides higher pressure to said sixth pump port relative to said fifth pump port;   a third hydraulic actuator having a fifth working port hydraulically connected to said fifth pump port of said third piston pump;   said third hydraulic actuator having a sixth working port hydraulically connected to said sixth pump port of said third piston pump;   wherein an external force applied to said third hydraulic actuator that provides higher pressure to said sixth pump port relative to said fifth pump port when said third stroke ring is in said third positive eccentric range applies an assistive torque to said drive shaft; and   wherein an external force applied to said third hydraulic actuator that provides higher pressure to said fifth pump port relative to said sixth pump port when said third stroke ring is in said third negative eccentric range applies an assistive torque to said drive shaft.   
     
     
         21 . The electro-hydraulic pump system set forth in  claim 20 , wherein said shaft comprises a first portion connected to said first cylinder block, a second portion connected to said second cylinder block, and a third portion connected to said third cylinder block. 
     
     
         22 . The electro-hydraulic pump system set forth in  claim 17 , comprising:
 a first hydraulic ring actuator connected to said first stroke ring and configured to selectively move said first stroke ring linearly in said first positive eccentric range between said first neutral position and said first positive eccentric position and to selectively move said first stroke ring linearly in said first negative eccentric range between said first neutral position and said first negative eccentric position; and   a second hydraulic ring actuator connected to said second stroke ring and configured to selectively move said second stroke ring linearly in said second positive eccentric range between said second neutral position and said second positive eccentric position and to selectively move said second stroke ring linearly in said second negative eccentric range between said second neutral position and said second negative eccentric position.   
     
     
         23 . (canceled) 
     
     
         24 . The electro-hydraulic pump system set forth in  claim 1 , wherein:
 said first fluid control journal comprises a first port plate;   said first displacement drive comprises a first swash plate orientated about said first displacement axis;   said first neutral position between said first displacement axis and said first block axis comprises a position in which said first displacement axis and said first block axis are coaxial;   said first swash plate is adapted to move angularly relative to said first neutral position;   said first maximum positive displacement position between said first displacement axis and said first block axis comprises a first positive angular position wherein said first displacement axis is offset from said first block axis in a first positive angular direction relative said first neutral position a first positive maximum cam angle;   said first positive displacement range comprises a first positive angular range between said first neutral position and a first positive angular position;   said first maximum negative displacement position between said first displacement axis and said first block axis comprises a first negative angular position wherein said first displacement axis is offset from said first block axis in a first negative angular direction relative said first neutral position a first negative maximum cam angle;   said first negative displacement range comprises a first negative angular range between said first neutral position and a first negative angular position;   rotation of said drive shaft when said first swash plate is in said first positive angular range provides higher pressure to said first pump port relative to said second pump port, and rotation of said drive shaft when said first swash plate is in said first negative angular range provides higher pressure to said second pump port relative to said first pump port;   said second fluid control journal comprises a second port plate;   said second displacement drive comprises a second swash plate orientated about said second displacement axis;   said second neutral position between said second displacement axis and said second block axis comprises a position in which said second displacement axis and said second block axis are coaxial;   said second swash plate is adapted to move angularly relative to said second neutral position;   said second maximum positive displacement position between said second displacement axis and said second block axis comprises a second positive angular position wherein said second displacement axis is offset from said second block axis in a second positive angular direction relative said second neutral position a second positive maximum cam angle;   said second positive displacement range comprises a second positive angular range between said second neutral position and a second positive angular position;   said second maximum negative displacement position between said second displacement axis and said second block axis comprises a second negative angular position wherein said second displacement axis is offset from said second block axis in a second negative angular direction relative said second neutral position a second negative maximum cam angle;   said second negative displacement range comprises a second negative angular range between said second neutral position and a second negative angular position;   rotation of said drive shaft when said second swash plate is in said second positive angular range provides higher pressure to said third pump port relative to said fourth pump port, and rotation of said drive shaft when said second swash plate is in said second negative angular range provides higher pressure to said fourth pump port relative to said third pump port;   an external force applied to said first hydraulic actuator that provides higher pressure to said second pump port relative to said first pump port when said first swash plate is in said first positive angular range applies an assistive torque to said drive shaft; and   an external force applied to said first hydraulic actuator that provides higher pressure to said first pump port relative to said second pump port when said first swash plate is in said first negative angular range applies an assistive torque to said drive shaft.   
     
     
         25 . The electro-hydraulic pump system set forth in  claim 24 , wherein:
 an external force applied to said second hydraulic actuator that provides higher pressure to said fourth pump port relative to said third pump port when said second swash plate is in said second positive angular range applies an assistive torque to said drive shaft; and   an external force applied to said second hydraulic actuator that provides higher pressure to said third pump port relative to said fourth pump port when said second swash plate is in said second negative angular range applies an assistive torque to said drive shaft.   
     
     
         26 . The electro-hydraulic pump system set forth in  claim 24 , comprising a battery supplying said current to said electric motor and wherein said motor is configured to selectively supply a current to said battery in a regeneration mode when:
 an external force applied to said first hydraulic actuator provides higher pressure to said second pump port relative to said first pump port when said first swash plate is in said first positive angular range or an external force applied to said first hydraulic actuator provides higher pressure to said first pump port relative to said second pump port when said first swash plate is in said first negative angular range; and   an external force applied to said second hydraulic actuator provides higher pressure to said fourth pump port relative to said third pump port when said second swash plate is in said second positive angular range or an external force applied to said second hydraulic actuator provides higher pressure to said third pump port relative to said fourth pump port when said second swash plate is in said second negative angular range.   
     
     
         27 . The electro-hydraulic pump system set forth in  claim 24 , comprising:
 a third hydraulic piston pump comprising a third port plate, a plurality of pistons in a third cylinder block adapted to rotate relative to said third port plate about a third block axis with rotation of said drive shaft, and a third swash plate orientated about a third swash plate axis and adapted to move angularly relative to a third neutral position in which said third swash plate axis and said third block axis are coaxial;   said third swash plate adapted to move angularly in a third positive angular range between said third neutral position and a third positive angular position, wherein said third swash plate axis is offset from said third block axis in a third positive angular direction relative said third neutral position a third positive maximum cam angle;   said third swash plate adapted to move angularly in a third negative angular range between said third neutral position and a third negative angular position, wherein said third swash plate axis is offset from said third block axis in a third negative angular direction opposite to said third positive angular direction relative to said third neutral position a third negative maximum cam angle;   said third port plate comprising a fifth pump port and a sixth pump port, wherein rotation of said drive shaft when said third swash plate is in said third positive angular range provides higher pressure to said fifth pump port relative to said sixth pump port, and wherein rotation of said drive shaft when said third swash plate is in said third negative angular range provides higher pressure to said sixth pump port relative to said fifth pump port;   a third hydraulic actuator having a fifth working port hydraulically connected to said fifth pump port of said third piston pump;   said third hydraulic actuator having a sixth working port hydraulically connected to said sixth pump port of said third piston pump;   wherein an external force applied to said third hydraulic actuator that provides higher pressure to said sixth pump port relative to said fifth pump port when said third swash plate is in said third positive angular range applies an assistive torque to said drive shaft; and   wherein an external force applied to said third hydraulic actuator that provides higher pressure to said fifth pump port relative to said sixth pump port when said third swash plate is in said third negative angular range applies an assistive torque to said drive shaft.   
     
     
         28 . The electro-hydraulic pump system set forth in  claim 27 , wherein said shaft comprises a first portion connected to said first cylinder block, a second portion connected to said second cylinder block, and a third portion connected to said third cylinder block. 
     
     
         29 . The electro-hydraulic pump system set forth in  claim 24 , comprising:
 a first hydraulic swash plate actuator connected to said first swash plate and configured to selectively move said first swash plate in said first positive angular range between said first neutral position and said first positive angular position and to selectively move said first swash plate in said first negative angular range between said first neutral position and said first negative angular position; and   a second hydraulic swash plate actuator connected to said second swash plate and configured to selectively move said second swash plate in said second positive angular range between said second neutral position and said second positive angular position and to selectively move said second swash plate in said second negative angular range between said second neutral position and said second negative angular position.   
     
     
         30 . (canceled) 
     
     
         31 . The electro-hydraulic pump system set forth in  claim 1 , wherein:
 said first fluid control journal comprises a first central control journal;   said first displacement drive comprises a first stroke ring orientated about said first displacement axis;   said first neutral position between said first displacement axis and said first block axis comprises a position in which said first displacement axis and said first block axis are coaxial;   said first stroke ring is adapted to move radially relative to said first neutral position;   said first maximum positive displacement position between said first displacement axis and said first block axis comprises a first positive eccentric position wherein said first displacement axis is offset from said first block axis in a first positive direction relative said first neutral position a first positive maximum eccentric distance;   said first positive displacement range comprises a first positive eccentric range between said first neutral position and a first positive eccentric position;   said first maximum negative displacement position between said first displacement axis and said first block axis comprises a first negative eccentric position wherein said first displacement axis is offset from said first block axis in a first negative direction relative said first neutral position a first negative maximum eccentric distance;   said first negative displacement range comprises a first negative eccentric range between said first neutral position and a first negative eccentric position;   rotation of said drive shaft when said first stroke ring is in said first positive eccentric range provides higher pressure to said first pump port relative to said second pump port, and rotation of said drive shaft when said first stroke ring is in said first negative eccentric range provides higher pressure to said second pump port relative to said first pump port;   said second fluid control journal comprises a first port plate;   said second displacement drive comprises a first swash plate orientated about said second displacement axis;   said second neutral position between said second displacement axis and said second block axis comprises a position in which said second displacement axis and said second block axis are coaxial;   said first swash plate is adapted to move angularly relative to said second neutral position;   said second maximum positive displacement position between said second displacement axis and said second block axis comprises a first positive angular position wherein said second displacement axis is offset from said second block axis in a first positive angular direction relative said second neutral position a first positive maximum cam angle;   said second positive displacement range comprises a first positive angular range between said second neutral position and a first positive angular position;   said second maximum negative displacement position between said second displacement axis and said second block axis comprises a first negative angular position wherein said second displacement axis is offset from said second block axis in a first negative angular direction relative said second neutral position a first negative maximum cam angle;   said second negative displacement range comprises a first negative angular range between said second neutral position and a first negative angular position;   rotation of said drive shaft when said first swash plate is in said first positive angular range provides higher pressure to said third pump port relative to said fourth pump port, and rotation of said drive shaft when said second swash plate is in said first negative angular range provides higher pressure to said fourth pump port relative to said third pump port;   an external force applied to said first hydraulic actuator that provides higher pressure to said second pump port relative to said first pump port when said first stroke ring is in said first positive eccentric range applies an assistive torque to said drive shaft; and   wherein an external force applied to said first hydraulic actuator that provides higher pressure to said first pump port relative to said second pump port when said first stroke ring is in said first negative eccentric range applies an assistive torque to said drive shaft.   
     
     
         32 . The electro-hydraulic pump system set forth in  claim 31 , wherein:
 an external force applied to said second hydraulic actuator that provides higher pressure to said fourth pump port relative to said third pump port when said first swash plate is in said first positive angular range applies an assistive torque to said drive shaft; and   an external force applied to said second hydraulic actuator that provides higher pressure to said third pump port relative to said fourth pump port when said first swash plate is in said first negative angular range applies an assistive torque to said drive shaft.