Hydraulic system health indicator

• US 7,204,138 B2
• Filed: 03/07/2006
• Issued: 04/17/2007
• Est. Priority Date: 07/28/2003
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Du, Hongliu
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): FITZGERALD, JOHN P
• Application Number:
  US11/369,333
• Publication Number:
  US 20060162439A1
• Time in Patent Office: 406 Days
• Field of Search: 731/68
• US Class Current: 73/168
• CPC Class Codes: F15B 19/005 Fault detection or monitoring

Abstract

A method and apparatus for determining the operating health of a hydraulic system are provided. The method may include the steps of determining a plurality of operating parameters of the hydraulic system during operation of the hydraulic system, determining an estimated working condition value of the hydraulic system, modifying the estimated working condition value as a function of the operating parameters, and determining the operating health of the hydraulic system as a function of the working condition value. In one method, the working condition value may be indicative of an effective bulk modulus value of an operating fluid within at least part of the hydraulic system.

Claims

1. A method for determining the operating health of a hydraulic system, the method comprising the steps of:

determining a plurality of operating parameters of the hydraulic system during operation of the hydraulic system;

using the operating parameters to determine one or more working condition values of the system;

wherein;

a first one of the one or more working condition values is indicative of an effective bulk modulus value of an operating fluid within at least part of the hydraulic system.

2. The method of claim 1, wherein the first working condition value is indicative of an effective bulk modulus value of an operating fluid within a hydraulic pump.

3. The method of claim 1, wherein the first working condition value is indicative of an effective bulk modulus value of an operating fluid within a hydraulic actuator.

4. The method of claim 1, wherein a second one of the one or more working condition values is indicative of an amount of leakage within at least part of the hydraulic system.

5. The method of claim 2, wherein at least one of the working condition values is indicative of a cavitation or entrapped air condition within at least part of the hydraulic system.

6. An apparatus for determining the operating health of a hydraulic system, the apparatus comprising:

a plurality of sensors operably connected to the hydraulic system and operable to indicate operating parameters of the hydraulic system during operation of the hydraulic system; and

at least one processor operably connected in electrical communication with the sensors, the at least one processor being operable to determine one or more working condition values as a function of the actual operating parameters, a first one of the one or more working condition values being indicative of an effective bulk modulus value of an operating fluid within at least part of the hydraulic system.

7. The apparatus of claim 6, wherein a second one of the one or more working condition values is indicative of an amount of leakage within at least part of the hydraulic system.

8. The apparatus of claim 6, wherein:

the hydraulic system includes first and second fluid drive members disposed in fluid communication with each other; and

the plurality of sensors includes a first sensor operably connected with the at least one processor and operable to indicate an operating pressure of the first fluid drive member and a second sensor operably connected with the at least one processor and operable to indicate an operating pressure of the second fluid drive member.

9. The apparatus of claim 8, wherein the plurality of sensors further includes:

a third sensor operably connected with the at least one processor and operable to indicate an operating speed or position of the first fluid drive member; and

a fourth sensor operably connected with the at least one processor and operable to indicate an operating speed or position of the second fluid drive member.

10. The apparatus of claim 6, wherein:

the hydraulic system includes a hydraulic pump and a hydraulic actuator disposed in fluid communication with the hydraulic pump; and

the plurality of sensors includes;

a first sensor operably connected with the at least one processor and operable to indicate an operating pressure of the pump;

a second sensor operably connected with the at least one processor and operable to indicate an operating speed of the pump;

a third sensor operably connected with the at least one processor and operable to indicate an operating pressure of the actuator; and

a fourth sensor operably connected with the at least one processor and operable to indicate an operating speed or position of the actuator.

11. The apparatus of claim 10, wherein the actuator is a hydraulic piston and cylinder arrangement.

12. The apparatus of claim 10, further comprising a swashplate;

wherein the plurality of sensors includes a fifth sensor operably connected with the at least one processor and operable to indicate a swashplate angle.