Load sensing control circuit

Patent metadata

Field	Value
Publication number	US-10024342-B2
Application number	US-201514898161-A
Country	US
Kind code	B2
Filing date	Apr 13, 2015
Priority date	May 26, 2014
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A pump discharge amount is divided in accordance with switch amounts of respective switch valves by leading load pressures of actuators to which compensator valves are connected to respective first pressure chambers of the compensator valves, leading a maximum load pressure selected by a selection unit to respective second pressure chambers of the compensator valves, and controlling respective openings of the compensator valves in accordance with respective pressure actions between the respective pressure chambers. A drain passage is provided to connect the first pressure chamber of the compensator valve to a tank, and a flow dividing ratio modification valve is provided to control a pressure in the first pressure chamber.

First claim

The invention claimed is:

1. A load sensing control circuit comprising:
a plurality of actuators;
a variable displacement pump that supplies a pressure fluid to the plurality of actuators;
switch valves provided respectively in connecting passages that connect the variable displacement pump to the respective actuators;
compensator valves provided respectively in the connecting passages between the switch valves and the actuators, the compensator valves each including a first pressure chamber and a second pressure chamber; and
a selection unit that selects a maximum load pressure of the plurality of actuators,
wherein the variable displacement pump is configured to discharge pressure fluid at a discharge amount corresponding to the load pressure selected by the selection unit; and
a pump discharge amount is divided in accordance with respective switch amounts of the switch valves by leading pressure between the compensator valves and the switch valves to the respective first pressure chambers of the compensator valves, leading the maximum load pressure selected by the selection unit to the respective second pressure chambers of the compensator valves, and controlling respective openings of the compensator valves in accordance with respective pressure actions between the first pressure chambers and the second pressure chambers,
the load sensing control circuit further comprising:
a drain passage that connects the first pressure chamber of at least one of the compensator valves to a tank; and
a pressure control unit provided in the drain passage and that controls a pressure in the first pressure chamber of the at least one of the compensator valves connected to the tank,
the pressure control unit is configured to open/close the drain passage, and when opening the drain passage, to increase a differential pressure between the first pressure chamber and the second pressure chamber of the at least one of the compensator valves and to decrease an opening degree of the at least one of the compensator valves compared with when closing the drain passage.

2. The load sensing control circuit as defined in claim 1 , wherein the pressure control unit comprises a flow dividing ratio modification valve that is provided in the drain passage and can be switched between a throttle position and a closed position.

3. The load sensing control circuit as defined in claim 2 , wherein the flow dividing ratio modification valve comprises a first throttle portion that throttles a flow in the throttle position, and
the first throttle portion has a variable opening.

4. The load sensing control circuit as defined in claim 2 , wherein the pressure control unit comprises a second throttle portion provided in a passage that connects the flow dividing ratio modification valve to a passage extending between the compensator valve in which the first pressure chamber of the at least one of the compensator valves is connected to the tank and one of the switch valves, and
the second throttle portion has a variable opening.

5. The load sensing control circuit as defined in claim 4 , wherein the drain passage is connected to a passage that connects the second throttle portion to the first pressure chamber of the at least one of the compensator valves.

6. The load sensing control circuit as defined in claim 1 , wherein the pressure control unit comprises:
a flow dividing ratio modification valve that is provided in the drain passage, can be switched between a throttle position and a closed position, and includes a first throttle portion that throttles a flow in the throttle position; and
a second throttle portion provided in a passage that connects the flow dividing ratio modification valve to a passage extending between the at least one of the compensator valves in which the first pressure chamber is connected to the tank and one of the switch valves, and
at least one of the first throttle portion and the second throttle portion has a variable opening.

7. The load sensing control circuit as defined in claim 1 , wherein the drain passage is connected to a passage that connects the first pressure chamber connected to the tank to a passage extending between one of the compensator valves in which the first pressure chamber is connected to the tank and one of the switch valves.

Assignees

• Kyb Corp

Inventors

• Terao Takeshi
• Nakamura Masayuki

Classifications

• F15B2211/3054

  the pressure compensating valve is arranged between directional control valve and output member · CPC title

• F15B2211/351

  Flow control by regulating means in feed line, i.e. meter-in control · CPC title

• F15B2211/20546

  variable capacity · CPC title

• F15B2211/50572

  using a pressure compensating valve for controlling the pressure difference across a flow control valve · CPC title

• F15B11/163 Primary

  for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation · CPC title