# US 9,518,378 B2 · Fluid pressure control device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,518,378 B2
- Document ID: US9518378B2
- Status: Granted
- Kind: B2
- Application number: 14/384,399
- Filed: 2013-03-25
- Published: 2015-04-09
- Granted: 2016-12-13
- Earliest claimed: 2012-03-27
- Assignees: KYB Corporation
- Applicants: Kayaba Industry Co., Ltd.
- Inventors: Tooru Takeuchi
- Web page: https://patentgrep.com/patent/US9518378B2

## CPC

- E02F 9/2285: {Pilot-operated systems}
- E02F 9/2203: {Arrangements for controlling the attitude of actuators, e.g. speed, floating function}
- E02F 9/2221: {Control of flow rate; Load sensing arrangements (E02F9/2203 take precedence over E02F9/2221)}
- E02F 9/2225: {using pressure-compensating valves}
- E02F 9/2267: {Valves or distributors (position of valves arrangements on upper-structures E02F9/0875)}
- F15B 11/003: {Systems with load-holding valves}
- F15B 11/044: by means in the return line (F15B11/046, F15B11/05 take precedence)
- F15B 13/01: Locking-valves or other detent {i.e. load-holding} devices
- F15B 13/021: {Valves for interconnecting the fluid chambers of an actuator}
- F15B 13/0402: {for linearly sliding valves, e.g. spool valves}
- F15B 13/0422: {with manually-operated pilot valves, e.g. joysticks}
- F16K 11/0716: {with fluid passages through the valve member (F16K11/0704, F16K11/0708, F16K11/0712 take precedence)}
- F16K 31/1221: {one side of the piston being spring-loaded}
- F15B 13/042: operated by fluid pressure {(F15B13/0401, F15B13/0416 take precedence)}
- F15B 2211/20576: with multiple pumps
- F15B 2211/30515: Load holding valves
- 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
- F15B 2211/3157: being connected to a pressure source, an output member and a return line
- F15B 2211/329: actuated by fluid pressure
- F15B 2211/353: Flow control by regulating means in return line, i.e. meter-out control
- F15B 2211/355: Pilot pressure control
- F15B 2211/365: Directional control combined with flow control and pressure control
- F15B 2211/40515: with variable throttles or orifices
- F15B 2211/41527: being connected to an output member and a directional control valve
- F15B 2211/428: actuated by fluid pressure
- F15B 2211/46: Control of flow in the return line, i.e. meter-out control
- F15B 2211/50545: using braking valves to maintain a back pressure
- F15B 2211/5151: being connected to a pressure source and a directional control valve
- F15B 2211/575: Pilot pressure control
- F15B 2211/7053: Double-acting output members
- F15B 2211/715: having braking means
- F15B 2211/761: Control of a negative load, i.e. of a load generating hydraulic energy
- E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00)
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F16K: VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING {(devices for emptying and evacuating the excess liquid in valves or conduits F16L55/07)}

## Abstract

A fluid pressure control device includes a switching valve that operates in conjunction with a control valve by a pilot pressure to switch an operation of an operated check valve. The switching valve includes a spool that moves according to the pilot pressure of a pilot chamber, and a piston that is accommodated in the pilot chamber and imparts a thrust force to the spool upon receiving the pilot pressure. The piston includes a first piston that is slidingly accommodated in the pilot chamber and is acted upon by the pilot pressure, and a second piston whose distal end faces the spool and is inserted into an accommodating hole formed in the first piston. A spherical protrusion is provided on a center of either one of a bottom surface of the accommodating hole of the first piston and a back surface of the second piston.

## Claims

### Claim 1

A fluid pressure control device comprising:
a cylinder that extends/retracts to drive a load by a working fluid supplied from a pump;
a control valve that switches supply/discharge of the working fluid to/from the cylinder to control an extension/retraction operation of the cylinder;
a pilot valve that pilot operates the control valve by a pilot pressure;
a main passage that connects the control valve to a load-side pressure chamber of the cylinder on which a load pressure by the load acts when the control valve is in a blocked position; and
a load-retaining mechanism that is interposed in the main passage and retains the load pressure of the load-side pressure chamber when the control valve is in the blocked position,
wherein the load-retaining mechanism comprises:
an operated check valve that permits a flow of the working fluid from the control valve to the load-side pressure chamber while also permitting a flow of the working fluid from the load-side pressure chamber to the control valve according to a pressure of a back pressure chamber to which pressure of the load-side pressure chamber is constantly led via a restriction passage; and
a switching valve that operates in conjunction with the control valve by a pilot pressure supplied via the pilot valve to switch an operation of the operated check valve,
wherein the switching valve comprises:
a pilot chamber to which the pilot pressure is supplied via the pilot valve;
a spool that moves according to the pilot pressure of the pilot chamber; and
a piston that is accommodated in the pilot chamber and imparts a thrust force to the spool upon receiving the pilot pressure at its back surface,
wherein the piston comprises:
a first piston that is slidingly accommodated in the pilot chamber and is acted upon by the pilot pressure at its back surface, and
a second piston whose distal end faces an end surface of the spool and is inserted coaxially with the first piston into an accommodating hole formed in the first piston, and
wherein a spherical protrusion is provided on a center of either one of a bottom surface of the accommodating hole of the first piston and a back surface of the second piston.

### Claim 2 (depends on 1)

The fluid pressure control device according to claim 1, wherein a gap that enables the second piston to tilt within the accommodating hole is formed between an inner peripheral surface of the accommodating hole of the first piston and an outer peripheral surface of the second piston.

### Claim 3 (depends on 2)

The fluid pressure control device according to claim 2, wherein the gap between the inner peripheral surface of the accommodating hole of the first piston and the outer peripheral surface of the second piston is set equal to or greater than dimensions that enable the second piston to tilt within the accommodating hole and equal to or less than dimensions that enable the bottom surface of the accommodating hole of the first piston and the second piston to abut each other via the protrusion.