Material moving machines and pilot hydraulic switching systems for use therein

Patent metadata

Field	Value
Publication number	US-2020354923-A1
Application number	US-201916407888-A
Country	US
Kind code	A1
Filing date	May 9, 2019
Priority date	May 9, 2019
Publication date	Nov 12, 2020
Grant date	—

Abstract

In accordance with one embodiment of the present disclosure, a material moving machine comprises a pilot hydraulic switching system. The pilot hydraulic switching system comprises a control unit, a first directional valve, and a second directional valve. The control unit is configured to operate the first and second directional valves to shift a variable position actuator valve between a static state, a retract state, and an extend state. The actuator valve comprises a first and second control element. In the retract and extend states, the first and second directional valves control fluid flow to the variable position actuator valve with a positive net pressure on either the first or second control elements and a negative net pressure on the other control element to move the material moving implement. In the static state, the first and second directional valves control fluid flow equally on the first and second control elements.

First claim

What is claimed is:

1 . A material moving machine comprising
a machine chassis, an implement support assembly, a material moving implement coupled to the machine chassis via the implement support assembly, a hydraulic fluid handling system, a variable position actuator valve, and a pilot hydraulic switching system, wherein: the implement support assembly comprises an implement actuator that is configured to move the material moving implement relative to the machine chassis; the hydraulic fluid handling system comprises a hydraulic fluid pump, a pump line fluidly coupled to the hydraulic fluid pump, a hydraulic fluid tank, a tank line fluidly coupled to the hydraulic fluid tank, a first actuator line fluidly coupled to the implement actuator, a second actuator line fluidly coupled to the implement actuator, an extend pilot line, and a retract pilot line; the variable position actuator valve comprises a first control element fluidly coupled to the extend pilot line, a second control element fluidly coupled to the retract pilot line, a pump port fluidly coupled to the pump line, a tank port fluidly coupled to the tank line, a first actuator-side port fluidly coupled to the first actuator line, and a second actuator-side port fluidly coupled to the second actuator line; the pilot hydraulic switching system comprises a switching system control unit, a first directional valve in fluid communication with the extend pilot line, and a second directional valve in fluid communication with the retract pilot line; the switching system control unit is configured to operate the first directional valve and the second directional valve; the first directional valve and the second directional valve are configured to shift the variable position actuator valve between a static state, a retract state, and an extend state; in the static state, the first and second directional valves control fluid flow to the variable position actuator valve to drive pressurized fluid in the extend pilot line and the retract pilot line simultaneously and equally against the first control element and the second control element of the variable position actuator valve to hold a positional state of the material moving implement as controlled by the implement actuator; in the retract state, the first and second directional valves control fluid flow to the variable position actuator valve to drive pressurized fluid in the extend pilot line and the retract pilot line simultaneously with a positive net pressure on the second control element of the variable position actuator valve and a negative net pressure on the first control element of the variable position actuator valve to retract the material moving implement under control of the implement actuator, and in the extend state, the first and second directional valves control fluid flow to the variable position actuator valve to drive pressurized fluid in the extend pilot line and the retract pilot line simultaneously with a positive net pressure of pressurized fluid on the first control element of the variable position actuator valve and a negative net pressure on the second control element of the variable position actuator valve to extend the material moving implement under control of the implement actuator.

2 . The material moving machine of claim 1 , wherein:
the material moving machine further comprises a translational chassis drive assembly that is configured to translate the material moving machine in a translational direction of operation; and the implement support assembly and the material moving implement are configured such that the material moving implement displaces material in an advancing path of the material moving implement as the material moving machine is translated by the drive assembly in the translational direction of operation.

3 . The material moving machine of claim 2 , wherein the advancing path of the material moving implement is parallel to the translational direction of operation of the material moving machine.

4 . The material moving machine of claim 2 , wherein:
the translational chassis drive assembly is configured to translate the material moving machine at a translational velocity of at least about 2 m/s in the translational direction of operation; and the variable position actuator valve and the pilot hydraulic switching system cooperate to shift the variable position actuator valve between the static state, the retract state, and the extend state as the material moving machine translates at the translational velocity.

5 . The material moving machine of claim 1 , wherein the implement actuator comprises an implement lift actuator or an implement pivot actuator.

6 . The material moving machine of claim 1 , wherein:
the implement actuator comprises an actuator cylinder; and the actuator cylinder is configured to move between extended and retracted positions in response to flow of hydraulic fluid into and out of the actuator cylinder by way of the first and second actuator lines.

7 . The material moving machine of claim 1 , wherein the first and second directional valves are fluidly coupled to the pump line with the pump port of the variable position actuator valve such that the first directional valve, the second directional valve, and the pump port of the variable position actuator valve are fluidly coupled to a common pump source.

8 . The material moving machine of claim 1 , wherein the first and second directional valves are fluidly coupled to the tank line with the tank port of the variable position actuator valve such that the first directional valve, the second directional valve, and the tank port of the variable position actuator valve are fluidly coupled to a common tank source.

9 . The material moving machine of claim 1 , wherein:
the first and second directional valves are fluidly coupled to the pump line with the pump port of the variable position actuator valve such that the first directional valve, the second directional valve, and the pump port of the variable position actuator valve are fluidly coupled to a common pump source; and the first and second directional valves are fluidly coupled to the tank line with the tank port of the variable position actuator valve such that the first directional valve, the second directional valve, and the tank port of the variable position actuator valve are fluidly coupled to a common tank source.

10 . The material moving machine of claim 1 , wherein the hydraulic fluid handling system, the variable position actuator valve, the first and second directional valves, and the implement actuator are configured to source hydraulic fluid from the hydraulic fluid pump and dispense hydraulic fluid to the hydraulic fluid tank.

11 . The material moving machine of claim 1 , wherein the variable position actuator valve comprises an opposing flow path mode, a counter flow path mode, and a blocked flow path mode.

12 . The material moving machine of claim 1 , wherein the switching system control unit is configured to:
complete a comparison of (i) a first target current output of the first directional valve to a first actual current output to the first directional valve via a first pulse width modulation percentage to the first directional valve to (ii) a second target current output to the second directional valve to a second actual current output to the second directional valve via a second pulse width modulation percentage of the second directional valve; and control the variable position actuator valve based on the comparison.

13 . The material moving machine of claim 12 , wherein the switching system control unit is configured to s

Assignees

• Caterpillar Trimble Control Tech Llc

Inventors

• Davis Kyle
• Piekutowski Richard Paul

Classifications

• F15B13/0433

  the pilot valves being pressure control valves (F15B13/0435, F15B13/0436, F15B13/0438 take precedence) · CPC title

• F15B2211/355

  Pilot pressure control · CPC title

• E02F9/2267

  Valves or distributors (position of valves arrangements on upper-structures E02F9/0875) · CPC title

• E02F9/2225

  using pressure-compensating valves · CPC title

• F15B2211/329

  actuated by fluid pressure · CPC title