Fault isolation and decontamination procedures for electrohydraulic valves

• US 9,658,626 B2
• Filed: 12/23/2013
• Issued: 05/23/2017
• Est. Priority Date: 12/26/2012
• Status: Active Grant

• Current Assignee: Danfoss A/S
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Mahulkar, Vishal Vijay, Rannow, Michael Berne
• Primary Examiner(s): Lopez, F. Daniel
• Assistant Examiner(s): Drake, Richard
• Application Number:
  US14/138,386
• Publication Number:
  US 20140174550A1
• Time in Patent Office: 1,247 Days
• Field of Search: 137 1506, 701 41, 701 50, 701 297
• CPC Class Codes: F15B 19/005 Fault detection or monitoring
• CPC Class Codes: F15B 2211/8636 Circuit failure, e.g. valve or hose failure
• CPC Class Codes: G05D 16/20 characterised by the use of electric means
• CPC Class Codes: G05D 7/0617 specially adapted for fluid materials
• CPC Class Codes: Y10T 137/0379 By fluid pressure

Abstract

A method for isolating a fault or blocked work port in an electro-hydraulic system is disclosed. In one step, a system pump is set to a first predetermined pressure and a valve assembly is commanded to a center position. In another step, the center position of the valve is recorded. In one step, the valve assembly is opened to place a work port associated with the valve in fluid communication with the pump, after which a first end position of the valve, a first work port pressure, and a first pump supply pressure are recorded. In another step, the valve assembly is opened to place the work port to a tank reservoir, after which a second end position of the valve and a fluid pressure associated with the work port are recorded. The recorded and measured data can then be analyzed to identify the fault condition or blocked work port.

Claims

1. A method for isolating a fault condition or a blocked work port in an electco-hydraulic system comprising:

(a) setting a system pump to a first predetermined pressure;

(b) commanding a valve assembly to a center position;

(c) recording a center position (xc) of the valve;

(d) opening the valve assembly to place a work port associated with the valve in fluid communication with the pump;

(e) recording a first end position (xp) of the valve, a first work port pressure (P1), and a first pump supply pressure (Ps);

(f) opening the valve assembly to place the work port in fluid communication with a tank reservoir;

(g) recording a second end position (xt) of the valve and a fluid pressure (Plow) associated with the work port;

(h) setting the pump to a second predetermined pressure;

(i) opening the valve assembly to place the work port in fluid communication with the pump;

(j) measuring a second work port pressure (P2) and a second system pump pressure (Ps2) associated with the pump; and

(k) analyzing the recorded and measured data to identify the fault condition or blocked work port, including comparing the second work port pressure (P2) to the second system pump pressure (Ps2) and by comparing the recorded first work port pressure (P1) to the second system pump pressure (Ps2).

2. The method for isolating a fault condition or a blocked work port in an electro-hydraulic system of claim 1, further comprising the steps of:

(a) recording the second work port pressure (P2) and the second system pump pressure (Ps2);

(b) setting the pump to a third predetermined pressure;

(c) opening the valve assembly to place the work port in fluid communication with the pump; and

(d) measuring a third work port pressure (P3) and a third system pump pressure (Ps3) associated with the pump.

3. The method for isolating a fault condition or a blocked work port in an electro-hydraulic system of claim 1, wherein the step of analyzing the recorded and measured data includes:

(a) comparing the recorded center position (xc), first end position (xp), and second end position (xt) to stored values in a controller.

4. The method for isolating a fault condition or a blocked work port in an electro-hydraulic system of claim 1, wherein the step of analyzing the recorded and measured data includes:

(a) comparing the first work port pressure (P1) to the first system pump pressure (Ps).

5. The method for isolating a fault condition or a blocked work port in an electro-hydraulic system of claim 2, wherein the step of analyzing the recorded and measured data includes:

(a) comparing the third work port pressure (P3) to the third system pump pressure (Ps3).

6. The method for isolating a fault condition or a blocked work port in an electro-hydraulic system of claim 5, wherein the step of analyzing the recorded and measured data includes:

(a) comparing the third work port pressure (P3) to the second system pump pressure (Ps2).

7. A method for isolating a blocked work port in an electro-hydraulic system comprising:

(a) configuring a first valve and a second valve associated with opposite sides of a actuator to switch between a flow control operational mode and a pressure control operational mode depending upon an operational state of the actuator, wherein only one of the valves is in a pressure control mode and only one of the valves is in a flow control mode at the same time;

(b) commanding a first valve and a second valve associated with an actuator to move the actuator in a first direction to place the actuator in a passive state or an overrunning state;

(c) comparing a design flow rate with a calculated flow rate for the valve in the flow control operational mode and comparing a system pressure set point with a measured work port pressure for the valve in the pressure control operational mode to identify and isolate the fault condition or blocked work port.

8. The method for isolating a blocked work port in an electro-hydraulic system of claim 7, further comprising:

(a) commanding the first valve and the second valve associated with the actuator to move the actuator in a second direction to place the actuator in a passive state or an overrunning state that is different from the actuator state of the first direction;

(b) comparing a second design flow rate with a second calculated flow rate for the valve in the flow control operational mode and comparing a second system pressure set point with a second measured work port pressure for the valve in the pressure control operational mode.

9. An anti-contamination method for a blocked work port in an electro-hydraulic system comprising the steps of:

(a) providing a first valve assembly and a second valve assembly associated with opposite sides of an actuator via a first and second work port;

(b) fully opening a second valve assembly associated with a second side of the actuator to place the second work port in fluid communication with a system pump;

(c) ramping an output of the system pump up to a maximum output for a period of time;

(d) pulsing the input to the second valve at a frequency;

(e) closing the second valve assembly and ramping the output of the pump downward; and

(f) repeating steps (b), (c), and (d) until the work port associated with the second valve assembly is freed from blockage or until a command is received to stop the procedure.

10. The anti-contamination method for a blocked work port in an electro-hydraulic system of claim 9, further comprising the step of:

(a) partially opening the first valve assembly.

11. The anti-contamination method for a blocked work port in an electro-hydraulic system of claim 9, wherein the step of pulsing the input to the second valve at a frequency includes pulsing the input to the second valve at a frequency of about 1 hertz.