Method and apparatus for determining the status of a relief valve

• US 6,408,676 B1
• Filed: 03/31/1999
• Issued: 06/25/2002
• Est. Priority Date: 03/31/1999
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Krause, Steven R., Pecchio, Patrick M., Stratton, Kenneth L., Skiba, Richard J., Genseal, Steven R.
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US09/282,381
• Time in Patent Office: 1,182 Days
• Field of Search: 73/17.2
• US Class Current: 73/1.72
• CPC Class Codes: F15B 11/165 for adjusting the pump output or bypass in response to demand
• CPC Class Codes: F15B 19/002 Calibrating
• CPC Class Codes: F15B 2211/205 Systems with pumps
• CPC Class Codes: F15B 2211/3055 the pressure compensating valve is arranged between directional control valve and return line
• CPC Class Codes: F15B 2211/3111 the pump port being closed in the centre position, e.g. so-called closed centre
• CPC Class Codes: F15B 2211/3144 the positions being continuously variable, e.g. as realised by proportional valves
• CPC Class Codes: F15B 2211/329 actuated by fluid pressure
• CPC Class Codes: F15B 2211/50536 using unloading valves controlling the supply pressure by diverting fluid to the return line
• CPC Class Codes: F15B 2211/55 for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
• CPC Class Codes: F15B 2211/6055 using pressure relief valves
• CPC Class Codes: F15B 2211/6309 the pressure being a pressure source supply pressure
• CPC Class Codes: F15B 2211/6313 the pressure being a load pressure
• CPC Class Codes: F15B 2211/6343 representing a temperature
• CPC Class Codes: F15B 2211/71 Multiple output members, e.g. multiple hydraulic motors or cylinders
• CPC Class Codes: F15B 2211/855 Testing of fluid pressure systems
• CPC Class Codes: F15B 2211/87 Detection of failures
• CPC Class Codes: F16K 37/0091 by measuring fluid parameters

Abstract

The present invention provides an apparatus and method for determining a status of a relief valve located within a fluid system having a pump and an actuator valve. The fluid system 102 is located on an earth moving machine, and the pump delivers fluid to the actuator 110, 112 through the actuator valve 108. The system 102 includes a pressure compensation assembly 130 adapted to control the fluid pressure of the system by bypassing fluid flow. The system 102 also includes a relief valve, and a pressure sensor. The method includes the steps of positioning the actuator valve in a closed position, deactivating the pressure compensation assembly, and sensing a relief pressure of the system.

Claims

1. A method for determining a status of a relief valve located within a fluid system having a pump and an actuator valve, the fluid system being located on an earth moving machine, the pump delivering fluid to an actuator through the actuator valve, the system including a pressure compensation assembly adapted to control the fluid pressure of the system by bypassing fluid flow, and a pressure sensor, comprising the steps of:

positioning the actuator valve in a closed position;

deactivating the pressure compensation assembly;

thereby deactivating the bypass flow; and

sensing a relief pressure of the system.

2. A method, as set forth in claim 1, including the step of activating the relief valve in response to said deactivation of the pressure compensation assembly.

3. A method, as set forth in claim 2, including the step of determining a status of the relief valve in response to said relief pressure.

4. A method, as set forth in claim 3, including the step of comparing said sensed relief pressure to a desired relief pressure.

5. A method, as set forth in claim 4, wherein said relief valve status includes one of calibrated and uncalibrated.

6. A method, as set forth in claim 5, including the steps of:

comparing said relief pressure with a desired relief pressure, and

determining said relief valve is calibrated in response to said relief pressure being within a threshold of said desired relief pressure.

7. A method, as set forth in claim 6, wherein the pressure compensation assembly includes a pressure compensation valve having a fluid test input, a fluid bias input, and a fluid output, wherein the step of deactivating the pressure compensation assembly includes the step of applying a main pump fluid pressure to the bias fluid input of the pressure compensation valve, and the main pump fluid pressure to the fluid test input.

8. A method, as set forth in claim 7, wherein the step of deactivating the pressure compensation assembly includes the step of activating the pressure compensation override valve in a manner to enable the main pump pressure fluid to be delivered to the bias fluid input of the pressure compensation valve.

9. A method, as set forth in claim 8, wherein the relief valve status determination is enabled in response to one of an operator input and an automated calibration procedure.

10. A method, as set forth in claim 9, including the steps of:

sensing an diagnostic associated with said fluid system; and

disabling said relief valve status determination in response to said sensed diagnostic.

11. A method, as set forth in claim 10, wherein said fluid is a hydraulic oil, including the steps of:

sensing a temperature of said oil; and

disabling said relief valve status determination in response to said oil temperature being less than a predetermined threshold.

12. A method, as set forth in claim 11, including the step of disabling said relief valve status determination after a predetermined amount of time.

13. A method, as set forth in claim 12, including the step of displaying said relief pressure to an operator of said machine.

14. A method, as set forth in claim 13, including the step of calibrating the relief valve in response to said relief valve status.

15. An apparatus adapted to determine a status of a relief valve located within a fluid system having a pump and an actuator valve, the fluid system being located on an earth moving machine, the pump delivering fluid to an actuator through the actuator valve comprising:

a pressure compensation assembly adapted to receive a pressure compensation command and responsively control the fluid pressure of the system, said assembly connecting the pump to a tank;

a pressure sensor adapted to sense the pressure of the fluid within the circuit and responsively generate a pressure signal; and

a controller adapted to receive said pressure signal, deliver an actuator valve command to the actuator valve thereby placing the actuator valve in a closed position, deliver said pressure compensation command to said pressure compensation assembly, said command placing the assembly in a deactivated position, determining a pressure of said fluid in response to said pressure signal and said deactivated pressure compensation assembly, and determining a status of the relief valve in response to said fluid pressure.

16. An apparatus, as set forth in claim 15, wherein said pressure compensation assembly includes:

a pressure compensation valve having a fluid test input, a fluid bias input, and a fluid output; and

a pressure compensation override valve adapted to receive said pressure compensation command and responsively deliver one of a main pump flow and a load pressure to said fluid bias input.

17. An apparatus, as set forth in claim 16, wherein said controller is further adapted to compare said sensed relief pressure to a desired relief pressure and responsively determine the relief valve status is one of a calibrated and an uncalibrated.

18. An apparatus, as set forth in claim 17, wherein said controller is adapted to receive an operator input signal, and enable said relief valve status determination in response to said input signal.

19. An apparatus, as set forth in claim 18, wherein said controller is adapted to detect a machine condition and disable said relief valve test in response to said condition.

20. An apparatus, as set forth in claim 19, including:

a display adapted to receive a relieve valve status signal from said controller and display said relief valve status.