Precision electro-hydraulic actuator positioning system
First Claim
1. An electro-hydraulic actuator system that comprises:
- a hydraulic actuator having a pair of fluid chambers and being operable to provide an actuator output as a function of fluid pressures in said chambers, an electric-hydrostatic actuator including an electric motor responsive to motor control signals for providing output at a motor shaft, piston means coupled to said shaft, and hydraulic cylinder means mounted on said motor and cooperable with said piston means for providing a pair of pump fluid cylinders respectfully coupled to said fluid chambers of said hydraulic actuator, a solenoid valve connected between said actuator chambers and responsive to valve control signals for feeding fluid between said chambers short circuiting said cylinders, a pair of pressure sensors coupled to said chambers for providing respective pressure signals as functions of fluid pressure in said chambers, and control means responsive to said pressure signals for providing said valve control signals and said motor control signals.
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Accused Products
Abstract
An electro-hydraulic actuator system (10 or 140) includes a hydraulic actuator (27) having a pair of fluid filled chambers (29, 30) and being operable to provide an actuator output (12) as a function of fluid pressures at the chambers. An electric-hydrostatic actuator (34 or 141) includes an electric motor (35 or 142) responsive to motor control signals for providing an output to a motor shaft (40 or 150), one or more pistons (56 or 166, 170) coupled to the shaft, and one or more hydraulic housings (92 or 160, 162) mounted on the motor and cooperating with the pistons for providing a pair of fluid cylinders (54 or 164, 168) respectively coupled to the fluid chambers at the hydraulic actuator. A solenoid valve (33) is connected between the cylinders, and is responsive to valve control signals for feeding fluid between the actuator chambers and thereby short circuiting the hydrostatic actuator cylinders. A pair of pressure sensors (80, 82) are coupled to the actuator chambers for providing respective pressure signals as a function of fluid pressure at the chambers, and a controller (92 or 202) is responsive to the pressure signals for providing the valve and motor control signals.
106 Citations
31 Claims
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1. An electro-hydraulic actuator system that comprises:
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a hydraulic actuator having a pair of fluid chambers and being operable to provide an actuator output as a function of fluid pressures in said chambers, an electric-hydrostatic actuator including an electric motor responsive to motor control signals for providing output at a motor shaft, piston means coupled to said shaft, and hydraulic cylinder means mounted on said motor and cooperable with said piston means for providing a pair of pump fluid cylinders respectfully coupled to said fluid chambers of said hydraulic actuator, a solenoid valve connected between said actuator chambers and responsive to valve control signals for feeding fluid between said chambers short circuiting said cylinders, a pair of pressure sensors coupled to said chambers for providing respective pressure signals as functions of fluid pressure in said chambers, and control means responsive to said pressure signals for providing said valve control signals and said motor control signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A power steering apparatus comprising:
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a hydraulic actuator having a pair of power assist cylinder chambers and operable to generate assisting power, a hydrostatic actuator for supplying pressurized fluid to said power assist chambers, an electric motor for operating said hydrostatic actuator, a control valve mechanism operable by a system controller for bypassing between said pair of power assist cylinder chambers of said hydraulic actuator the pressurized fluid supplied by said hydrostatic actuator, pressure sensors for detecting differential pressure between pressures in said pair of power assist cylinder chambers, and a motor control responsive to the output of said pressure sensors for controlling said electric motor thereby to cause said motor to drive said hydrostatic actuator in accordance with steering wheel position so as to return the differential pressure to a predetermined first value, said hydrostatic actuator comprising a double-acting actuator piston and cylinder unit having a pair of working chambers separated by said actuator piston and respectively communicating with said pair of power assist cylinder chambers, said electric motor being operable bidirectionally axially to drive a leadscrew on which said piston is mounted for travel in response to axial motion of said leadscrew.
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19. An electro-hydraulic power steering system that comprises:
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an elongated rack adapted to be connected at opposite ends to steerable wheels of a motor vehicle, said rack having a series of teeth along a section of its length, a rotatable steering gear in mesh with the rack teeth and adapted to be operably connected to a steering wheel of the vehicle by a shaft so as to receive vehicle operator steering input, said rack extending lengthwise within an elongated housing constructed to form an elongated power assist cylinder, a piston carried by said rack and separating said power assist cylinder into first and second power assist working chambers filled with hydraulic fluid, an electric-hydrostatic actuator including an electric motor responsive to motor control signals for providing an output to a motor shaft, piston means coupled to said shaft, and hydraulic cylinder means mounted on said motor and cooperating with said piston means for providing a pair of pump fluid cylinders respectively coupled to first and second power assist working chambers, a solenoid valve connected between said chambers and responsive to valve control signals for feeding fluid between said chambers, a pair of pressure sensors coupled to said power assist working chambers for providing respective pressure signals as a function of fluid pressure in said chambers, which in turn are responsive at least in part to steering input through said shaft, and control means responsive to said pressure signals for providing said valve control signal and said motor control signal. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification