# US 12,000,416 B2 · Work machine

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- Number: US 12,000,416 B2
- Document ID: US12000416B2
- Status: Granted
- Kind: B2
- Application number: 17/637,533
- Filed: 2021-03-12
- Published: 2022-09-15
- Granted: 2024-06-04
- Earliest claimed: 2020-03-27
- Assignees: Hitachi Construction Machinery Co., Ltd.
- Applicants: Hitachi Construction Machinery Co., Ltd.
- Inventors: Kento Kumagai; Shinya Imura; Yasutaka Tsuruga; Takaaki Chiba; Hiroaki Amano; Shinji Nishikawa; Akihiro Narazaki
- Web page: https://patentgrep.com/patent/US12000416B2

## CPC

- F15B 21/045: Compensating for variations in viscosity or temperature
- E02F 9/2004: {Control mechanisms, e.g. control levers (control levers per se G05G)}
- E02F 9/2203: {Arrangements for controlling the attitude of actuators, e.g. speed, floating function}
- E02F 9/2228: {including an electronic controller}
- E02F 9/2267: {Valves or distributors (position of valves arrangements on upper-structures E02F9/0875)}
- E02F 9/2271: {Actuators and supports therefor and protection therefor}
- E02F 9/2282: {Systems using center bypass type changeover valves}
- E02F 9/2285: {Pilot-operated systems}
- E02F 9/2292: {Systems with two or more pumps}
- E02F 9/26: Indicating devices {(E02F5/145 takes precedence)}
- F15B 11/042: by means in the feed line (F15B11/046, F15B11/05 take precedence)
- F15B 13/025: {Pressure reducing valves}
- F15B 13/026: {Pressure compensating valves}
- F15B 13/0405: {for seat valves, i.e. poppet valves}
- F15B 13/044: operated by electrically-controlled means, e.g. solenoids, torque-motors
- E02F 3/32: working downwardly and towards the machine, e.g. with backhoes
- E02F 3/425: {Drive systems for dipper-arms, backhoes or the like}
- E02F 3/435: {for dipper-arms, backhoes or the like}
- E02F 9/2296: {Systems with a variable displacement pump}
- F15B 13/0433: {the pilot valves being pressure control valves (F15B13/0435, F15B13/0436, F15B13/0438 take precedence)}
- F15B 2211/30535: the pressure compensating valve is arranged between pressure source and directional control valve
- F15B 2211/327: electrically or electronically
- F15B 2211/329: actuated by fluid pressure
- F15B 2211/351: Flow control by regulating means in feed line, i.e. meter-in control
- F15B 2211/355: Pilot pressure control
- F15B 2211/6309: the pressure being a pressure source supply pressure
- F15B 2211/6313: the pressure being a load pressure
- F15B 2211/6336: representing a state of the output member, e.g. position, speed or acceleration
- F15B 2211/6343: representing a temperature
- F15B 2211/6346: representing a state of input means, e.g. joystick position
- F15B 2211/6355: having valve means
- F15B 2211/6654: Flow rate control
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00)

## Abstract

A work machine that can keep the control accuracy of actuators irrespective of temperature variation of a hydraulic operating fluid that passes through flow rate controllers that control the flow rates of supply to the actuators is provided. For this purpose, the flow rate controllers each have a valve body that is disposed on a main hydraulic line connecting a delivery line of a hydraulic pump and the actuator and that moves according to an operation pressure from a solenoid proportional pressure reducing valve, a sampling hydraulic line that branches from the main hydraulic line, and a temperature sensor set on the sampling hydraulic line. The controller is configured to correct a command electrical signal to the solenoid proportional pressure reducing valve according to a signal from the temperature sensor.

## Claims

### Claim 1

A work machine comprising:
a machine body;
a work device attached to the machine body;
actuators that drive the machine body or the work device;
a hydraulic pump;
flow rate controllers that are connected in parallel to a delivery line of the hydraulic pump and adjust a flow of a hydraulic fluid supplied from the hydraulic pump to the actuators;
an operation lever for making an instruction of operation of the actuators;
a pilot pump;
solenoid proportional pressure reducing valves that reduce pressure of the hydraulic fluid supplied from the pilot pump and output a resulting pressure as an operation pressure of the respective flow rate controllers; and
a controller that outputs a command electrical signal to the solenoid proportional pressure reducing valves according to an operation amount instructed from the operation lever,
wherein the flow rate controllers each have:
a valve body that is disposed on a main hydraulic line connecting the delivery line and one of the actuators and moves according to the operation pressure from the corresponding solenoid proportional pressure reducing valve,
a sampling hydraulic line that branches from the main hydraulic line, and
a temperature sensor set on the sampling hydraulic line,
wherein the controller is configured to correct the command electrical signal according to a signal from the temperature sensor,
wherein the valve body is a seat valve body,
wherein the flow rate controllers each have:
a main housing in which the seat valve body is housed,
a pilot housing that encloses the seat valve body in the main housing,
a hydraulic chamber formed between the seat valve body and the pilot housing, and
a pilot variable restrictor that is disposed on the pilot line and changes an opening area according to the operation pressure from the corresponding solenoid proportional pressure reducing valve,
wherein a control variable restrictor is formed in the seat valve body and changes an opening area according to the movement amount of the seat valve body, the control variable restrictor connecting a hydraulic line part and the hydraulic chamber, the hydraulic line part connecting the hydraulic pump and the seat valve body in the main hydraulic line,
wherein the sampling hydraulic line is a pilot line that connects a downstream side of the seat valve body and the hydraulic chamber, the sampling hydraulic line deciding a movement amount of the seat valve body according to a passing flow rate.

### Claim 2

A work machine, comprising:
a machine body;
a work device attached to the machine body;
actuators that drive the machine body or the work device;
a hydraulic pump;
flow rate controllers that are connected in parallel to a delivery line of the hydraulic pump and adjust a flow of a hydraulic fluid supplied from the hydraulic pump to the actuators;
an operation lever for making an instruction of operation of the actuators;
a pilot pump;
solenoid proportional pressure reducing valves that reduce pressure of the hydraulic fluid supplied from the pilot pump and output a resulting pressure as an operation pressure of the respective flow rate controllers; and
a controller that outputs a command electrical signal to the solenoid proportional pressure reducing valves according to an operation amount instructed from the operation lever,
wherein the flow rate controllers each have:
a valve body that is disposed on a main hydraulic line connecting the delivery line and one of the actuators and moves according to the operation pressure from the corresponding solenoid proportional pressure reducing valve,
a sampling hydraulic line that branches from the main hydraulic line, and
a temperature sensor set on the sampling hydraulic line,
wherein the controller is configured to correct the command electrical signal according to a signal from the temperature sensor,
wherein the valve body is a spool valve body,
wherein the flow rate controllers each further have
a check valve body disposed on a hydraulic line part connecting the hydraulic pump and the spool valve body in the main hydraulic line,
a main housing in which the spool valve body and the check valve body are housed,
a cap that encloses the check valve body in the main housing,
a hydraulic chamber formed between the check valve body and the cap, and
wherein the sampling hydraulic line is a communication hydraulic line that establishes communication between a downstream side of the check valve body and the hydraulic chamber.