Void protection system

Patent metadata

Field	Value
Publication number	US-9206583-B2
Application number	US-201313860281-A
Country	US
Kind code	B2
Filing date	Apr 10, 2013
Priority date	Apr 10, 2013
Publication date	Dec 8, 2015
Grant date	Dec 8, 2015

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.

First claim

What is claimed is:

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 each having an opening 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 and control the hydraulic cylinder based on the movement of the operator input device, and, when there is no movement at the operator input device, to:
monitor pressure within the head end and the rod end of the hydraulic cylinder by receiving signals from the sensor assembly;
when the signals indicate that the pressure in the rod end or the head end of the hydraulic cylinder is below a first threshold pressure, increase the 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 the pressure in the corresponding end is above a second threshold pressure; and
when the signals indicate that the pressure in the rod end or the head end of the hydraulic cylinder is greater than the second threshold pressure, reduce the opening of the 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 independen

Assignees

• Caterpillar Global Mining Llc

Inventors

• Beschorner Matthew J
• Johnson Bryan A
• Janson Brett J
• Barnes Brandon Z
• Cesur Rustu

Classifications

• F15B2211/30575

  in a Wheatstone Bridge arrangement (also half bridges) · CPC title

• E02F9/2217

  with energy recovery arrangements, e.g. using accumulators, flywheels · CPC title

• E02F9/226

  Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating · CPC title

• F15B2211/3058

  having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode · CPC title

• F15B2211/7053

  Double-acting output members · CPC title