Hydraulic system

Patent metadata

Field	Value
Publication number	US-8943819-B2
Application number	US-201113278939-A
Country	US
Kind code	B2
Filing date	Oct 21, 2011
Priority date	Oct 21, 2011
Publication date	Feb 3, 2015
Grant date	Feb 3, 2015

Abstract

A hydraulic system includes a variable displacement first pump, a first linear actuator fluidly connected to the first pump via a first closed-loop circuit, a variable displacement second pump, and second and third linear actuators fluidly connected to the second pump in parallel via a second closed-loop circuit. The system also includes a variable displacement third pump, a fourth linear actuator fluidly connected to the third pump via a third closed-loop circuit, a variable displacement fourth pump, and a first rotary actuator fluidly connected to the fourth pump via a fourth closed-loop circuit. The system further includes a second rotary actuator fluidly connected to the second pump in parallel with the second and third linear actuators. The system also includes a third rotary actuator fluidly connected to the third pump in parallel with the fourth linear actuator.

First claim

What is claimed is:

1. A hydraulic system, comprising:
a variable displacement first pump;
a first linear actuator fluidly connected to the first pump via a first closed-loop circuit;
a variable displacement second pump;
second and third linear actuators fluidly connected to the second pump in parallel via a second closed-loop circuit;
a variable displacement third pump;
a fourth linear actuator fluidly connected to the third pump via a third closed-loop circuit;
a variable displacement fourth pump;
a first rotary actuator fluidly connected to the fourth pump via a fourth closed-loop circuit;
a second rotary actuator fluidly connected to the second pump in parallel with the second and third linear actuators;
a third rotary actuator fluidly connected to the third pump in parallel with the fourth linear actuator; and
a first combining valve configured to selectively combine fluid from the second and third circuits, a second combining valve configured to selectively combine fluid from the first and second circuits, and a third combining valve configured to selectively combine fluid from the third and fourth circuits, wherein the second combining valve is moveable between a flow-passing position and a flow blocking position, the second combining valve directing fluid from the first and second circuits to at least one of the first, second, and third linear actuators and the second rotary actuator in the flow-passing position.

2. The system of claim 1 , further comprising a first switching valve associated with the first linear actuator, a second switching valve associated with the second and third linear actuators, and a third switching valve associated with the second rotary actuator, each of the switching valves being configured to selectively switch a flow direction of fluid passing through the respective actuators.

3. The system of claim 2 , wherein the second switching valve is configured to reduce a speed of the second and third linear actuators during regeneration of the second and third linear actuators.

4. The system of claim 2 , wherein the second combining valve is configured to form a combined flow of fluid including fluid from the first and second circuits, during simultaneous operation of the first linear actuator with the second and third linear actuators and the second rotary actuator, in response to a combined demand of the second and third linear actuators and the second rotary actuator exceeding a capacity of the second pump.

5. The system of claim 4 , wherein the second switching valve is configured to variably restrict passage of the combined flow through the second and third linear actuators, during simultaneous operation of the first linear actuator with the second and third linear actuators and the second rotary actuator.

6. The system of claim 4 , wherein the first switching valve is configured to selectively switch a flow direction of fluid passing through the first linear actuator independent of a flow direction of the combined flow passing through the second and third actuators, during simultaneous operation of the first linear actuator with the second and third linear actuators and the second rotary actuator.

7. The system of claim 4 , wherein the third switching valve is configured to selectively switch a flow direction of fluid passing through the second rotary actuator independent of a flow direction of the combined fluid passing through the second and third actuators, during simultaneous operation of the first linear actuator with the second and third linear actuators and the second rotary actuator.

8. A hydraulic system, comprising:
a variable displacement first pump;
a first linear actuator fluidly connected to the first pump via a first closed-loop circuit:
a variable displacement second pump;
second and third linear actuators fluidly connected to the second pump in parallel via a second closed-loop circuit;
a variable displacement third pump;
a fourth linear actuator fluidly connected to the third pump via a third closed-loop circuit;
a variable displacement fourth pump;
a first rotary actuator fluidly connected to the fourth pump via a fourth closed-loop circuit;
a second rotary actuator fluidly connected to the second pump in parallel with the second and third linear actuators;
a third rotary actuator fluidly connected to the third pump in parallel with the fourth linear actuator;
a first combining valve configured to selectively combine fluid from the second and third circuits, a second combining valve configured to selectively combine fluid from the first and second circuits, and a third combining valve configured to selectively combine fluid from the third and fourth circuits; and
a first switching valve associated with the first linear actuator, a second switching valve associated with the second and third linear actuators, and a third switching valve associated with the second rotary actuator, each of the switching valves being configured to selectively switch a flow direction of fluid passing through the respective actuators, wherein at least one of the switching valves comprises
a variable position four-way valve.

9. A hydraulic system, comprising:
a variable displacement first Pump;
a first linear actuator fluidly connected to the first pump via a first closed-loop circuit:
a variable displacement second pump;
second and third linear actuators fluidly connected to the second pump in parallel via a second closed-loop circuit;
a variable displacement third pump;
a fourth linear actuator fluidly connected to the third pump via a third closed-loop circuit;
a variable displacement fourth pump;
a first rotary actuator fluidly connected to the fourth pump via a fourth closed-loop circuit;
a second rotary actuator fluidly connected to the second pump in parallel with the second and third linear actuators;
a third rotary actuator fluidly connected to the third pump in parallel with the fourth linear actuator; and
a first combining valve configured to selectively combine fluid from the second and third circuits, a second combining valve configured to selectively combine fluid from the first and second circuits, and a third combining valve configured to selectively combine fluid from the third and fourth circuits,
wherein the first and second combining valves are configured to combine fluid from the first, second, and third circuits, during simultaneous operation of the second, third, and fourth linear actuators, in response to a combined demand of the second and third linear actuators exceeding a combined capacity of the first and second pumps.

10. The system of claim 9 , wherein the third combining valve is configured to combine fluid from the fourth circuit with fluid from the first, second, and third circuits, during simultaneous operation of the second, third, and fourth linear actuators, in response to a combined demand of the second and third actuators exceeding a combined capacity of the first, second, and third pumps.

11. A hydraulic system, comprising:
a variable displacement first pump;
a first hydraulic cylinder associated with a work tool of a machine, the first hydraulic cylinder being fluidly connected to the first pump via a first closed-loop circuit;
a variable displacement second pump;
second and third hydraulic cylinders associated with a boom of the machine, the second and third hydraulic cylinders being fluidly connected to the second pump in parallel via a second closed-loop circuit;
a variable displacement third pump;
a fourth hydraulic cylinder associated with a stick of the machine, the fourth hydraulic cylinder being fluidly connected to the third pump via a third closed-loop circuit;
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Assignees

• Knussman Michael L
• Caterpillar Inc

Inventors

• Knussman Michael L

Classifications

• F15B2211/7053

  Double-acting output members · CPC title

• F15B2211/20546

  variable capacity · CPC title

• F15B2211/3144

  the positions being continuously variable, e.g. as realised by proportional valves · CPC title

• F15B2211/27

  Directional control by means of the pressure source · CPC title

• F15B2211/3111

  the pump port being closed in the centre position, e.g. so-called closed centre · CPC title