Construction machine

Patent metadata

Field	Value
Publication number	US-11199205-B2
Application number	US-201916961006-A
Country	US
Kind code	B2
Filing date	Jan 10, 2019
Priority date	Jan 11, 2018
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

An object of the present invention is to provide a construction machine that allows easy and accurate calibration of a pressure sensor and enables accurate control of hydraulic actuators. A controller increases the delivery pressure of a hydraulic pump in a state in which first and second meter-out valves and a second meter-in valve are closed and in which a first meter-in valve is opened, and calibrates a first pressure-calculation map such that a pressure calculated on the basis of the first pressure-calculation map matches a pressure calculated on the basis of a supply-pressure-calculation map, and increases the delivery pressure of the hydraulic pump in a state in which the first and second meter-out valves and the first meter-in valve are closed and in which the second meter-in valve is opened, and calibrates a second pressure-calculation map such that a pressure calculated on the basis of the second pressure-calculation map matches the pressure calculated on the basis of the supply-pressure-calculation map.

First claim

The invention claimed is:

1. A construction machine comprising:
a hydraulic pump;
a supply hydraulic line connected to the hydraulic pump;
a tank;
a discharge hydraulic line connected to the tank;
a hydraulic actuator having a first oil chamber and a second oil chamber;
a first-actuator hydraulic line connected to the first oil chamber;
a second-actuator hydraulic line connected to the second oil chamber;
a first meter-in valve provided on a first connection hydraulic line connecting the supply hydraulic line and the first-actuator hydraulic line;
a second meter-in valve provided on a second connection hydraulic line connecting the supply hydraulic line and the second-actuator hydraulic line;
a first meter-out valve provided on a third connection hydraulic line connecting the first-actuator hydraulic line and the discharge hydraulic line;
a second meter-out valve provided on a fourth connection hydraulic line connecting the second-actuator hydraulic line and the discharge hydraulic line;
a bleed-off valve provided on a fifth connection hydraulic line connecting the supply hydraulic line and the discharge hydraulic line;
a supply-pressure sensor that senses a delivery pressure of the hydraulic pump;
a first-load-pressure sensor that senses a pressure of the first oil chamber;
a second-load-pressure sensor that senses a pressure of the second oil chamber; and
a controller that controls the first and second meter-in valves, the first and second meter-out valves, and the bleed-off valve in accordance with sensing signals of the first and second-load-pressure sensors, and a sensing signal of the supply-pressure sensor, wherein
the controller is configured to:
calculate the delivery pressure of the hydraulic pump from the sensing signal of the supply-pressure sensor on a basis of a supply-pressure-calculation map representing a characteristic of the supply-pressure sensor,
calculate the pressure of the first oil chamber from the sensing signal of the first-load-pressure sensor on a basis of a first pressure-calculation map representing a characteristic of the first-load-pressure sensor,
calculate the pressure of the second oil chamber from the sensing signal of the second-load-pressure sensor on a basis of a second pressure-calculation map representing a characteristic of the second-load-pressure sensor,
increase the delivery pressure of the hydraulic pump in a state in which the first and second meter-out valves and the second meter-in valve are closed and in which the first meter-in valve is opened, and calibrate the first pressure-calculation map such that the pressure of the first oil chamber calculated on the basis of the first pressure-calculation map matches the delivery pressure of the hydraulic pump calculated on the basis of the supply-pressure-calculation map, and
increase the delivery pressure of the hydraulic pump in a state in which the first and second meter-out valves and the first meter-in valve are closed and in which the second meter-in valve is opened, and calibrate the second pressure-calculation map such that the pressure of the second oil chamber calculated on the basis of the second pressure-calculation map matches the delivery pressure of the hydraulic pump calculated on the basis of the supply-pressure-calculation map.

2. The construction machine according to claim 1 , further comprising:
a first-valve-position sensor that senses a valve position of the first meter-in valve; and
a second-valve-position sensor that senses a valve position of the second meter-in valve, wherein
the controller is further configured to:
calculate the valve position of the first meter-in valve from a sensing signal of the first-valve-position sensor on a basis of a first position-calculation map representing a characteristic of the first-valve-position sensor, and
calculate the valve position of the second meter-in valve from a sensing signal of the second-valve-position sensor on a basis of a second position-calculation map representing a characteristic of the second-valve-position sensor, and

the controller is further configured to:
actuate the first meter-in valve in a state in which the first and second meter-out valves and the second meter-in valve are closed, and calibrate the first position-calculation map such that the valve position of the first meter-in valve calculated on the basis of the first position-calculation map when the first meter-in valve is at a minimum position becomes a minimum position, and the valve position of the first meter-in valve calculated on the basis of the first position-calculation map when the first meter-in valve is at a maximum position becomes a maximum position, or
actuate the second meter-in valve in a state in which the first and second meter-out valves and the first meter-in valve are closed, and calibrate the second position-calculation map such that the valve position of the second meter-in valve calculated on the basis of the second position-calculation map when the second meter-in valve is at a minimum position becomes a minimum position, and the valve position of the second meter-in valve calculated on the basis of the second position-calculation map when the second meter-in valve is at a maximum position becomes a maximum position.

3. The construction machine according to claim 1 , wherein
the controller is further configured to:
actuate the bleed-off valve in a state in which the first and second meter-out valves and the second meter-in valve are closed and in which the first meter-in valve is opened, and calibrate the first pressure-calculation map such that the pressure of the first oil chamber calculated on the basis of the first pressure-calculation map matches the delivery pressure of the hydraulic pump calculated on the basis of the supply-pressure-calculation map, or
actuate the bleed-off valve in a state in which the first and second meter-out valves and the first meter-in valve are closed and in which the second meter-in valve is opened, and calibrate the second pressure-calculation map such that the pressure of the second oil chamber calculated on the basis of the second pressure-calculation map matches the delivery pressure of the hydraulic pump calculated on the basis of the supply-pressure-calculation map.

4. The construction machine according to claim 1 , wherein the supply-pressure sensor is installed on a hydraulic line portion of a hydraulic line connecting the hydraulic pump and the first or second meter-in valve, the hydraulic line portion excluding a hydraulic line portion connecting the hydraulic pump and the bleed-off valve.

Assignees

• Hitachi Construction Mach Co

Inventors

• Moriki Hidekazu
• Chiba Takaaki
• Imura Shinya

Classifications

• F15B2211/634

  representing a state of a valve · CPC title

• F15B2211/426

  electrically or electronically · CPC title

• F15B2211/41518

  being connected to multiple pressure sources · CPC title

• F15B2211/30505

  Non-return valves, i.e. check valves · CPC title

• F15B2211/20576

  with multiple pumps · CPC title