Actuator control system and method

• US 20070204603A1
• Filed: 01/19/2007
• Published: 09/06/2007
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Allen Rasmussen, Kenneth Cowan, Michael Jacobs
• Original Assignee: Allen Rasmussen, Kenneth Cowan, Michael Jacobs
• Inventors: Jacobs, Michael, Rasmussen, Allen, Cowan, Kenneth
• Granted Patent: US 7,621,123 B2
• Time in Patent Office: Days
• US Class Current: 60/428
• CPC Class Codes: F15B 21/087 Control strategy, e.g. with block diagram
• CPC Class Codes: F15B 2211/20515 Electric motor
• CPC Class Codes: F15B 2211/20538 constant capacity
• CPC Class Codes: F15B 2211/633 representing a state of the prime mover, e.g. torque or rotational speed
• CPC Class Codes: F15B 2211/6655 Power control, e.g. combined pressure and flow rate control
• CPC Class Codes: F15B 2211/6656 Closed loop control, i.e. control using feedback
• CPC Class Codes: F15B 2211/7053 Double-acting output members
• CPC Class Codes: F15B 2211/7058 Rotary output members

Abstract

Actuator control system and method comprising an electric motor driving a hydraulic pump in fluid delivery communication with a source of hydraulic fluid; a variable speed controller operatively coupled to the motor for driving the pump at variable speeds; an external hydraulic actuator in fluid delivery communication with the pump for receiving pressurized fluid flow from the pump; and a feedback loop operatively coupled from the motor to the controller for providing feedback signals correlative to a pressure of the pressurized fluid flow through the driven pump for driving the external hydraulic actuator in response to the feedback signals for providing electronic velocity and force control of actuation of the external hydraulic actuator. The actuator control system and method can operate on one or many high-pressure hydraulic linear and/or rotary actuators on different pieces of hydraulically driven equipment and with different velocity requirements actuating in different directions.

Claims

1. An actuator control system, comprising:

a source of hydraulic fluid;

a pump in fluid delivery communication with said source of hydraulic fluid;

an electric motor operatively coupled to said pump for driving said pump for supplying a pressurized fluid flow of hydraulic fluid from said source of hydraulic fluid;

a solenoid operated directional valve in fluid delivery communication with said pump for receiving said pressurized fluid flow of hydraulic fluid supplied from said pump and allowing said pressurized fluid flow through said solenoid operated directional valve upon operation thereof;

a hydraulic actuator in fluid delivery communication with said pressurized fluid flow through said solenoid operated directional valve for moving a member of said hydraulic actuator at a velocity and force upon operation of said solenoid operated directional valve;

a variable speed controller operatively coupled to said electric motor; and

a motor feedback loop operatively coupled from said electric motor to said variable speed controller for providing feedback signals correlative to a pressure of said pressurized fluid flow for driving said member of said hydraulic actuator in response to said feedback signals for providing electronic velocity and force control of actuation of said member of said hydraulic actuator.

2. The actuator control system of claim 1 further including a system controller for controlling the operation of said solenoid operated directional valve for directing said pressurized fluid flow through said solenoid operated directional valve to said hydraulic actuator for providing directional control of said hydraulic actuator.

3. The actuator control system of claim 2 further including a common enclosure enclosing said system controller, said source of hydraulic fluid;

said pump;

said electric motor;

said solenoid operated directional valve;

said variable speed controller; and

said motor feedback loop.

4. The actuator control system of claim 3 wherein said hydraulic actuator is external to said common enclosure.

5. The actuator control system of claim 4 wherein said hydraulic actuator is a linear actuator with said member being a piston capable of moving at said velocity either in a first direction or in a second opposite direction upon operation by the system controller of said solenoid operated directional valve for directing said pressurized fluid flow through said solenoid operated directional valve to said hydraulic actuator for moving said piston at said controlled velocity either in said first direction or in said second opposite direction.

6. The actuator control system of claim 5 further including a first and a second limit switch operatively coupled between said actuator and said control system for feeding back position signals to said control system relative to said actuator piston reaching a first desired position or a second different desired position wherein said control systems signals said solenoid operated directional valve to shift into a closed position and signals the motor controller to stop the electric drive motor for stopping said hydraulic pump.

7. The actuator control system of claim 6 further including a pilot operated check valve interposed between said solenoid operated directional valve and said actuator for locking oil in said actuator for preventing said actuator piston from movement until fluid pressure is generated by said electric drive motor driving said hydraulic pump for generating said pressurized fluid flow of hydraulic fluid to said solenoid operated directional valve.

8. The actuator control system of claim 1 wherein said feedback signals are a function of electric motor operating current.

9. The actuator control system of claim 1 wherein said feedback signals are a function of electric motor operating voltage.

10. The actuator control system of claim 1 wherein said feedback signals are a function of motor operating horsepower.

11. The actuator control system of claim 1 wherein said feedback signals are a function of electric motor operating velocity.

12. The actuator control system of claim 1 wherein said feedback signals are a function of electric motor operating torque.

13. The actuator control system of claim 1 wherein said hydraulic actuator is a rotary actuator and said member is a rotary member.

14. The actuator control system of claim 1 wherein said motor is intermittently driven by said motor controller between a low torque high velocity state and a high torque low velocity state in response to said feedback signals for moving the actuator at a high velocity when a low load is sensed and at a low velocity when a high load is sensed.

15. An actuator control system, comprising:

a reservoir of hydraulic fluid providing a source of hydraulic fluid;

a pump mounted in fluid delivery communication with said source of hydraulic fluid;

an electric motor operatively coupled to said pump for driving said pump for supplying a pressurized flow of hydraulic fluid from said source of hydraulic fluid;

a variable speed controller operatively coupled to said electric motor for driving said electric motor at variable speeds;

a hydraulic actuator in fluid delivery communication with said pump for receiving said pressurized flow of hydraulic fluid from said pump; and

a feedback loop operatively coupled from said electric motor to said variable speed controller for providing feedback signals from said motor to said variable speed controller for intermittently driving said motor between a first low torque and high velocity state in response to said feedback signals being correlative to a low load being placed on said hydraulic actuator and a second high torque and low velocity state in response to said feedback signals being correlative to a high load condition being placed on said hydraulic actuator.

16. The actuator control system of claim 15 further including a common enclosure enclosing said reservoir, said pump, said electric motor, said variable speed motor controller, and said feedback loop within said common enclosure.

17. The actuator control system of claim 16 wherein said hydraulic actuator is external to said common enclosure.

18. The actuator control system of claim 17 wherein said hydraulic actuator is a linear actuator.

19. The actuator control system of claim 17 wherein said hydraulic actuator is a rotary actuator.

20. An actuator control method for controlling a hydraulic actuator, comprising the steps of:

driving a pump in fluid delivery communication with a source of hydraulic fluid with an electric motor for supplying a pressurized fluid flow of hydraulic fluid from the driven pump;

controlling a running speed of the electric motor as a function of feedback signals from the motor correlative to a pressure of the pressurized fluid flow through the driven pump;

providing a high-pressure hydraulic actuator in fluid delivery communication with the pump for receiving the pressurized fluid flow of hydraulic fluid from the pump; and

driving the high-pressure hydraulic actuator at a variable velocity in response to the feedback signals correlative to the pressure of the pressurized fluid flow through the driven pump for controlling a velocity and force of actuation of the hydraulic actuator.

21. The actuator control method of claim 20 wherein the step of controlling the running speed of the electric motor as a function of feedback signals from the motor correlative to the pressure of fluid flow through the driven pump further includes a step of determining if the pressure of fluid flow is at an acceptable level for performing a step of continuing the step of driving the pump at a set speed upon a determination that the pressure of fluid flow is at an acceptable level and for performing a step of opening a relief valve upon a determination that the pressure of fluid flow is at an unacceptable level.

22. The actuator control method of claim 21 wherein the step of controlling the running speed of the electric motor as a function of feedback signals from the motor correlative to the pressure of fluid flow through the driven pump further includes a step of subsequently determining if the pressure of fluid flow is at an acceptable level for performing a step of opening the relief valve upon a determination that the pressure of fluid flow is at an unacceptable level and for performing the step of driving the pump at a reduced speed from the set speed upon a determination that the pressure of fluid flow is at an acceptable level.

23. The actuator control method of claim 22 further including a step of opening a temperature switch as a result of fluid temperature rising resulting from the step of opening the relief valve and further including a step of activating a fault light after the step of opening the temperature switch.

24. The actuator control method of claim 22 further including a step of determining when the actuator reaches a predetermined position with a limit switch feedback for deactivating the motor and the driving of the pump.

25. The actuator control method of claim 24 further including a step of activating a position light after the step of determining that the actuator has reached the predetermined position with the limit switch feedback for deactivating the motor and the driving of the pump.