Method and apparatus for controlling the deadband of a fluid system

• US 6,305,162 B1
• Filed: 03/31/1999
• Issued: 10/23/2001
• Est. Priority Date: 03/31/1999
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Janson, Brett J., Dietz, Hans P., Cobo, Michael A., OʼNeill, William N.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): Lazo, Thomas E.
• Application Number:
  US09/282,339
• Time in Patent Office: 937 Days
• Field of Search: 604/22, 604/31, 604/63
• US Class Current: 60/422
• CPC Class Codes: E02F 9/2221 Control of flow rate; Load sensing arrangements E02F9/2203 take precedence over E02F9/2221
• CPC Class Codes: E02F 9/2228 including an electronic controller
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: F15B 19/00 Testing; Calibrating; Fault detection or monitoring; Simulation or modelling of fluid-pressure systems or apparatus not otherwise provided for
• CPC Class Codes: F15B 21/087 Control strategy, e.g. with block diagram

Abstract

The present invention provides a method and apparatus for controlling a fluid system. The fluid system includes a hydraulic circuit having a pump driven by an engine. The pump delivers fluid to an actuator through a valve assembly. The method includes the steps of receiving an operator input, determining a condition of the hydraulic circuit, determining a valve command in response to the circuit condition and the operator input, and delivering the valve command to the valve assembly.

Claims

1. a method for controlling a fluid system, the system including a hydraulic circuit having a pump driven by an engine, the pump delivering fluid to an actuator through a valve assembly, comprising:

receiving an operator input;

determining a condition of the hydraulic circuit, said condition including at least one of a fluid flow rate, a pump speed, and a pump displacement;

determining a valve transform function as a function of the condition of the hydraulic circuit;

determining a valve command in response to said valve transform function and said operator input, said valve command resulting in a consistent deadband; and

delivering said valve command to the valve assembly.

2. A method, as set forth in claim 1, including the step of establishing a first deadband.

3. A method, as set forth in claim 2, wherein said circuit condition is at least one of an engine speed and a pump displacement.

4. A method, as set forth in claim 3, wherein the step of determining said valve command includes determining said valve command in response to said first deadband, said circuit condition, and said operator input.

5. A method, as set forth in claim 4, including the step of determining a valve command offset in response to a previous circuit condition, said circuit condition, and said first deadband.

6. A method, as set forth in claim 5, wherein said valve command is determined in response to said command offset, said circuit condition, and said operator input.

7. A method, as set forth in claim 6, wherein said consistent deadband is within a predetermined threshold of said first deadband.

8. A method, as set forth in claim 7, wherein said first deadband is established in response to said previous circuit condition, a previous operator input, and a previous valve command.

9. A method, as set forth in claim 8, including the step of determining a work function of the hydraulic circuit, said valve command being determined in response to said operator input, said circuit condition, and said work function.

10. A method, as set forth in claim 9, wherein said consistent deadband is a first motion deadband.

11. A method, as set forth in claim 10, wherein said first motion deadband includes a valve assembly deadband.

12. A method, as set forth in claim 11, wherein said circuit condition includes at least one of a fluid flow rate, a fluid pressure, and a fluid temperature.

13. a method for controlling a fluid system, the system including a hydraulic circuit having a pump driven by an engine, the pump delivering fluid to an actuator through a valve assembly, comprising the steps of:

establishing a first motion deadband;

receiving an operator input;

determining at least one of an engine speed and a pump displacement;

determining a valve transform function as a function said at least one of said engine speed and said pump displacement; and

determining a valve command in response to said valve transform function and said operator input, wherein said valve command results in said first motion deadband.

14. A method, as set forth in claim 13, wherein the step of establishing a first motion deadband includes the steps of:

determining at least one of an initial engine speed and a pump displacement;

determining a first operator input;

determining a first valve command in response to said first fluid condition; and

wherein said first motion deadband is established in response to said first valve command.

15. an apparatus adapted to control a fluid system, the system including a hydraulic circuit having a pump driven by an engine, the pump delivering fluid to an actuator through a valve assembly, comprising:

an input controller adapted to receive an operator input and responsively generate an input signal;

engine speed sensor adapted to sense a speed of the engine and responsively generate an engine speed signal;

and a controller adapted to receive said input signal and said speed signal, determine a valve transform function in response to said engine speed signal, and to determine a valve command in response to said input signal and said valve transform function, said valve command resulting in a consistent deadband, and to deliver said valve command to the valve assembly.

16. An apparatus, as set forth in claim 15, wherein said controller is further adapted to establish a first motion deadband, and wherein said valve command results in said established first motion deadband.

17. An apparatus for controlling a fluid system, the system including a hydraulic circuit having a pump driven by an engine, the pump operable to deliver fluid to an actuator through a valve assembly, comprising:

means for receiving an operator input;

means for determining a condition of the hydraulic circuit, the condition being indicative of a fluid flow rate of the hydraulic circuit;

means for determining a valve transform function as a function of the condition of the hydraulic circuit;

means for determining a valve command as a function of the valve transform function and the operator input, the valve command operable to cause a consistent deadband; and

means for delivering the valve command to the valve assembly.