VOID PROTECTION SYSTEM

• US 20140308106A1
• Filed: 04/10/2013
• Published: 10/16/2014
• Est. Priority Date: 04/10/2013
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Beschorner, Matthew J., Johnson, Bryan A., Cesur, Rustu, Janson, Brett J., Barnes, Brandon Z.
• Granted Patent: US 9,206,583 B2
• Time in Patent Office: Days
• US Class Current: 414/685
• CPC Class Codes: E02F 3/46 with reciprocating digging or scraping elements moved by cables or hoisting ropes ; Drives or control devices therefor E02F3/205, E02F3/905 take precedence
• CPC Class Codes: E02F 9/2207 for reducing or compensating oscillations
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/226 Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
• CPC Class Codes: E02F 9/2267 Valves or distributors position of valves arrangements on upper-structures E02F9/0875
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: F15B 21/047 Preventing foaming, churning or cavitation
• CPC Class Codes: F15B 2211/30565 having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
• CPC Class Codes: F15B 2211/30575 in a Wheatstone Bridge arrangement (also half bridges)
• CPC Class Codes: F15B 2211/3058 having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode directional control valves having a regenerative position F15B2211/3133; directional control valves having a floating position F15B2211/3127
• CPC Class Codes: F15B 2211/6313 the pressure being a load pressure
• CPC Class Codes: F15B 2211/6346 representing a state of input means, e.g. joystick position
• CPC Class Codes: F15B 2211/7053 Double-acting output members
• CPC Class Codes: F15B 2211/8609 the abnormal condition being cavitation
• CPC Class Codes: Y10T 137/87917 Flow path with serial valves and/or closures

Abstract

A void protection system for a mining shovel having an operator input device includes an independent metering valve assembly including one or more fluid source-cylinder valves for fluidly connecting the fluid source to the hydraulic cylinder. The system also includes a sensor assembly for monitoring the fluid pressure within the rod end and the head end of the hydraulic cylinder, and a control module. The control module is configured to monitor movement of the operator input device, monitor pressure within the hydraulic cylinder, increase the opening of the corresponding fluid source-cylinder valve and increase fluid flow from the fluid source to fill corresponding end of the hydraulic cylinder until pressure in the corresponding end of the hydraulic cylinder is above a first threshold pressure.

Claims

1. A mining shovel, comprising:

a boom assembly;

a hydraulic cylinder having a rod end and a head end;

a dipper coupled to the boom assembly such that movement of the hydraulic cylinder moves the dipper;

an independent metering valve assembly coupled to the hydraulic cylinder and to a fluid source, the assembly comprising;

one or more fluid source-cylinder valves for fluidly connecting the fluid source to the hydraulic cylinder;

an operator input device;

a sensor assembly for monitoring the fluid pressure within the rod end and the head end of the hydraulic cylinder;

a control module configured to;

monitor movement of the operator input device;

when there is no movement at the operator input device, monitor pressure within the head end and the rod end of the hydraulic cylinder by receiving signals from the sensor assembly;

when pressure in the rod end or the head end of the hydraulic cylinder decreases below a first threshold pressure, increase opening of the corresponding fluid source-cylinder valve and increase fluid flow from the fluid source to fill the corresponding end of the hydraulic cylinder until pressure in the corresponding end is above a second threshold pressure; and

when pressure in the rod end or the head end of the hydraulic cylinder increases beyond the second threshold pressure, reduce opening of corresponding fluid source-cylinder valve and decrease fluid flow from the fluid source.

2. The mining shovel of claim 1, wherein the independent metering valve assembly further comprises:

a head end-rod end valve for fluidly connecting the head end to the rod end;

wherein the control module is configured to;

when pressure in the head end of the hydraulic cylinder decreases below the first threshold pressure, increase the opening of the head end-rod end valve and route fluid from the rod end to fill the head end until pressure in the head end is above the second threshold pressure; and

when pressure in the rod end of the hydraulic cylinder decreases below the first threshold pressure, increase the opening of the head end-rod end valve and route fluid from the head end to fill the rod end until pressure in the rod end is above the second threshold pressure.

3. The mining shovel of claim 2, wherein the control module is configured to:

when pressure in the head end and the rod end of the hydraulic cylinder increases beyond the second threshold pressure, reduce opening of the head end-rod end valve.

4. The mining shovel of claim 1, further comprising:

a second hydraulic cylinder having a second rod end and a second head end;

wherein the pressure sensor assembly monitors the fluid pressure within the second rod end and the second head end;

wherein the independent metering valve assembly is coupled to the second hydraulic cylinder and further comprises a fluid source-second cylinder valve for fluidly connecting the fluid source to the second hydraulic cylinder;

wherein the control module is configured to;

when there is no movement at the operator input device, monitor pressure within the second head end and the second rod end by receiving signals from the sensor assembly;

when pressure in the second rod end or the second head end decreases below a third threshold pressure, increase opening of the corresponding fluid source-second cylinder valve and increase fluid flow from the fluid source to fill the corresponding end of the second hydraulic cylinder until pressure in the corresponding end is above a fourth threshold pressure; and

when pressure in the second rod end or the second head end increases beyond the fourth threshold pressure, reduce opening of corresponding fluid source-second cylinder valve and decrease fluid flow from the fluid source.

5. The mining shovel of claim 4, wherein the independent metering valve assembly further comprises:

a second head end-second rod end valve for fluidly connecting the second head end to the second rod end;

wherein the control module is configured to;

when pressure in the second head end decreases below the third threshold pressure, increase the opening of the second head end-second rod end valve and route fluid from the second rod end to fill the second head end until pressure in the second head end is above the fourth threshold pressure; and

when pressure in the second rod end of the hydraulic cylinder decreases below the third threshold pressure, increase the opening of the second head end-second rod end valve and route fluid from the second head end to fill the second rod end until pressure in the second rod end is above the fourth threshold pressure.

6. The mining shovel of claim 1, further comprising:

an accumulator fluidly coupled to the independent metering valve assembly;

wherein the control module is configured;

when pressure in the rod end or the head end of the hydraulic cylinder decreases below a first threshold pressure, route fluid from the accumulator to fill the corresponding end of the hydraulic cylinder until pressure in the corresponding end is above the second threshold pressure; and

when pressure in the rod end or the head end of the hydraulic cylinder increases beyond the second threshold pressure, decrease fluid flow from the accumulator.

7. The mining shovel of claim 6, wherein the independent metering valve assembly further comprises:

an accumulator-cylinder valve for fluidly connecting the accumulator to the hydraulic cylinder;

wherein the control module is configured to;

when pressure in the rod end or the head end of the hydraulic cylinder decreases below a first threshold pressure, increase opening of the corresponding accumulator-cylinder valve to fill the corresponding end of the hydraulic cylinder until pressure in the corresponding end is above a second threshold pressure; and

when pressure in the rod end or the head end of the hydraulic cylinder increases beyond the second threshold pressure, reduce opening of corresponding accumulator-cylinder valve.

8. The mining shovel of claim 6, wherein the independent metering valve assembly further comprises:

a check valve fluidly coupled to the accumulator;

wherein the check valve is configured to prevent fluid having a fluid pressure below a predetermined level from flowing outside of the independent metering valve assembly.

9. The mining shovel of claim 1, wherein the control module is configured to:

when pressure in the rod end of the hydraulic cylinder decreases below a first threshold pressure, increase opening of a fluid source-head end valve and increase fluid flow from the fluid source to fill the head end of the hydraulic cylinder until pressure in the rod end is above a second threshold pressure;

when pressure in the head end of the hydraulic cylinder decreases below a first threshold pressure, increase opening of a fluid source-rod end valve and increase fluid flow from the fluid source to fill the rod end of the hydraulic cylinder until pressure in the head end is above a second threshold pressure;

when pressure in the rod end of the hydraulic cylinder increases beyond the second threshold pressure, reduce opening of the fluid source-head end valve and decrease fluid flow from the fluid source; and

when pressure in the head end of the hydraulic cylinder increases beyond the second threshold pressure, reduce opening of the fluid source-rod end valve and decrease fluid flow from the fluid source.

10. The mining shovel of claim 1, wherein the independent metering valve assembly comprises more than one independent metering valve arrangement for routing fluid to the hydraulic cylinder.

11. The mining shovel of claim 1, wherein the independent metering valve assembly comprises:

a relief valve coupled to the fluid source; and

a relief pressure sensor for measuring the fluid pressure at the relief valve;

wherein the control module is configured to cause the relief valve to release fluid from the independent metering valve assembly when the fluid pressure at the relief valve reaches a predetermined pressure.

12. The mining shovel of claim 1, wherein the independent metering valve assembly comprises:

a first fluid path for fluidly connecting the fluid source to the rod end of the hydraulic cylinder; and

a second fluid path for fluidly connecting the fluid source to the head end of the hydraulic cylinder;

wherein the fluid source-cylinder valves comprise;

a first valve coupled to the first fluid path and configured to controllably block the first fluid path; and

a second valve coupled to the second fluid path and configured to controllably block the second fluid path.

13. The mining shovel of claim 1, wherein the sensor assembly comprises:

one or more sensors configured to measure the displacement of the hydraulic cylinder;

wherein the sensor assembly is configured to monitor the fluid pressure within the rod end and the head end of the hydraulic cylinder by measuring the displacement of the hydraulic cylinder.

14. The mining shovel of claim 1, wherein the sensor assembly comprises:

one or more sensors configured to measure the velocity of the hydraulic cylinder;

wherein the sensor assembly is configured to monitor the fluid pressure within the rod end and the head end of the hydraulic cylinder by measuring the velocity of the hydraulic cylinder.

15. A void protection system for a mining shovel having an operator input device, the system comprising:

an independent metering valve assembly configured to couple to a fluid source and to a hydraulic cylinder having a rod end and a head end, the assembly comprising;

one or more fluid source-cylinder valves for fluidly connecting the fluid source to the hydraulic cylinder;

a sensor assembly for monitoring the fluid pressure within the rod end and the head end of the hydraulic cylinder;

a control module configured to;

monitor movement of the operator input device;

when there is no movement at the operator input device, monitor pressure within the head end and the rod end of the hydraulic cylinder by receiving signals from the sensor assembly;

when pressure in the rod end or the head end of the hydraulic cylinder decreases below a first threshold pressure, increase opening of corresponding fluid source-cylinder valve and increase fluid flow from the fluid source to fill corresponding end of the hydraulic cylinder until pressure in the corresponding end of the hydraulic cylinder is above the first threshold pressure; and

when pressure in the rod end or the head end of the hydraulic cylinder increases beyond a second threshold pressure, reduce opening of corresponding fluid source-cylinder valve and decrease fluid flow from the fluid source.

16. The system of claim 15, wherein the independent metering valve assembly further comprises:

a head end-rod end valve for fluidly connecting the head end to the rod end;

wherein the control module is configured to;

when pressure in the head end of the hydraulic cylinder decreases below the first threshold pressure, increase the opening of the head end-rod end valve and route fluid from the rod end to fill the head end until pressure in the head end is above the second threshold pressure; and

when pressure in the rod end of the hydraulic cylinder decreases below the first threshold pressure, increase the opening of the head end-rod end valve and route fluid from the head end to fill the rod end until pressure in the rod end is above the second threshold pressure.

17. The system of claim 15, wherein the control module is configured to:

when pressure in the rod end of the hydraulic cylinder decreases below a first threshold pressure, increase opening of a fluid source-head end valve and increase fluid flow from the fluid source to fill the head end of the hydraulic cylinder until pressure in the rod end is above a second threshold pressure;

when pressure in the head end of the hydraulic cylinder decreases below a first threshold pressure, increase opening of a fluid source-rod end valve and increase fluid flow from the fluid source to fill the rod end of the hydraulic cylinder until pressure in the head end is above a second threshold pressure;

when pressure in the rod end of the hydraulic cylinder increases beyond the second threshold pressure, reduce opening of the fluid source-head end valve and decrease fluid flow from the fluid source; and

when pressure in the head end of the hydraulic cylinder increases beyond the second threshold pressure, reduce opening of the fluid source-rod end valve and decrease fluid flow from the fluid source.

18. The system of claim 15, wherein the independent metering valve assembly further comprises:

a first fluid path for fluidly connecting the fluid source to the rod end of the hydraulic cylinder; and

a second fluid path for fluidly connecting the fluid source to the head end of the hydraulic cylinder;

wherein the fluid source-cylinder valves comprise;

a first valve coupled to the first fluid path and configured to controllably block the first fluid path; and

a second valve coupled to the second fluid path and configured to controllably block the second fluid path.

19. An independent metering valve assembly for a hydraulic system, the assembly comprising:

a first fluid path for fluidly connecting a fluid source to a rod end of a hydraulic cylinder;

a first valve coupled to the first fluid path and configured to controllably block the first fluid path;

a second fluid path for fluidly connecting a fluid source to a head end of the hydraulic cylinder; and

a second valve coupled to the second fluid path and configured to controllably block the second fluid path;

wherein the first and second valves are configured to controllably open when the fluid pressure within the corresponding end decreases below a first fluid pressure threshold, and wherein the first and second valves are configured to controllably close when the fluid pressure within the corresponding end increases above a second fluid pressure threshold.

20. The assembly of claim 19, further comprising:

a third fluid path for fluidly connecting the rod end of the hydraulic cylinder to the head end of the hydraulic cylinder; and

a third valve coupled to the third fluid path and configured to controllably block the third fluid path;

wherein the third valve is configured to controllably open when the fluid pressure within the rod end or the head end decreases below the first fluid pressure threshold, and wherein the third valve is configured to controllably close when the fluid pressure within the rod end and head end increases above the second fluid pressure threshold.