Control system, work machine, and control method

• US 10,385,545 B2
• Filed: 07/29/2016
• Issued: 08/20/2019
• Est. Priority Date: 07/29/2016
• Status: Active Grant

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Kamoshita, Yuta, Kawaguchi, Tadashi, Akiyama, Teruo
• Primary Examiner(s): Teka, Abiy
• Application Number:
  US15/506,799
• Publication Number:
  US 20180030692A1
• Time in Patent Office: 1,117 Days
• CPC Class Codes: E02F 9/2228 including an electronic controller
• CPC Class Codes: E02F 9/2242 including an electronic controller
• CPC Class Codes: E02F 9/2253 Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 11/163 for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
• CPC Class Codes: F15B 11/17 using two or more pumps
• CPC Class Codes: F15B 19/007 Simulation or modelling
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/3054 the pressure compensating valve is arranged between directional control valve and output member
• CPC Class Codes: F15B 2211/30595 with additional valves between the groups of valves for multiple output members
• CPC Class Codes: F15B 2211/6309 the pressure being a pressure source supply pressure
• CPC Class Codes: F15B 2211/6313 the pressure being a load pressure
• CPC Class Codes: F15B 2211/6333 representing a state of the pressure source, e.g. swash plate angle
• CPC Class Codes: F15B 2211/6652 Control of the pressure source, e.g. control of the swash plate angle
• CPC Class Codes: F15B 2211/6654 Flow rate control
• CPC Class Codes: F16H 61/4008 Control of circuit pressure
• CPC Class Codes: F16H 61/47 for achieving a target output speed

Abstract

A control system includes a cylinder pressure data acquisition unit that acquires cylinder pressure data indicating a pressure of operating oil of a hydraulic cylinder; an operation amount data acquisition unit that acquires operation amount data of an operating device; a pump flow rate calculation unit that calculates a first pump flow rate indicating a flow rate of the operating oil discharged from a first hydraulic pump and a second pump flow rate indicating a flow rate of the operating oil discharged from a second hydraulic pump in a splitting state in which a passage is closed based on the cylinder pressure data and the operation amount data; and a pump control unit that controls the first hydraulic pump and the second hydraulic pump based on the first pump flow rate and the second pump flow rate.

Claims

1. A control system that controls a work machine including a working unit and a plurality of hydraulic cylinders that drives the working unit, comprising:

a first hydraulic pump and a second hydraulic pump that discharge operating oil to be supplied to the plurality of hydraulic cylinders;

a passage that connects the first hydraulic pump and the second hydraulic pump;

an opening and closing device that is provided in the passage so as to open and close the passage;

an operating device that is operated to drive the plurality of hydraulic cylinders;

a cylinder pressure data acquisition unit that acquires cylinder pressure data indicating a pressure of the operating oil of the plurality of hydraulic cylinders;

an operation amount data acquisition unit that acquires operation amount data of the operating device;

a pump flow rate calculation unit that calculates a first pump flow rate indicating a flow rate of the operating oil discharged from the first hydraulic pump and a second pump flow rate indicating a flow rate of the operating oil discharged from the second hydraulic pump in a splitting state in which the passage is closed based on the cylinder pressure data and the operation amount data;

a pump control unit that controls the first hydraulic pump and the second hydraulic pump in the splitting state based on the first pump flow rate and the second pump flow rate;

a relief valve that prevents an increase in a pressure of the operating oil; and

a relief flow rate calculation unit that calculates a relief flow rate indicating a flow rate of the operating oil discharged via the relief valve based on a pump limit flow rate indicating a flow rate of the operating oil that the first hydraulic pump and the second hydraulic pump can discharge and a sum of distribution flow rates of the operating oil distributed to the plurality of hydraulic cylinders,

wherein the pump control unit controls the first hydraulic pump and the second hydraulic pump based on the relief flow rate.

2. The control system according to claim 1, wherein

in the splitting state, the first hydraulic pump discharges the operating oil to be supplied to a first hydraulic cylinder group including at least one of the hydraulic cylinders,

in the splitting state, the second hydraulic pump discharges the operating oil to be supplied to a second hydraulic cylinder group including at least one of the hydraulic cylinders,

the first pump flow rate is determined based on a flow rate of the operating oil required by the first hydraulic cylinder group to be driven based on the operation amount, and

the second pump flow rate is determined based on a flow rate of the operating oil required by the second hydraulic cylinder group to be driven based on the operation amount.

3. The control system according to claim 2, wherein

the working unit includes a bucket, an arm connected to the bucket, and a boom connected to the arm,

the plurality of hydraulic cylinders includes a bucket cylinder that drives the bucket, an arm cylinder that drives the arm, and a boom cylinder that drives the boom, and

the first hydraulic cylinder group includes the bucket cylinder and the arm cylinder and the second hydraulic cylinder group includes the boom cylinder.

4. The control system according to claim 1, further comprising:

a main operating valve that adjusts the flow rate of the operating oil supplied to the plurality of hydraulic cylinders based on a pilot pressure generated when the operating device is operated; and

an operation amount detection unit that detects the pilot pressure, wherein

the operation amount data is calculated based on a detection signal of the operation amount detection unit.

5. The control system according to claim 1, wherein

when a merging state in which the passage is open is switched to the splitting state, the pump control unit controls the first hydraulic pump and the second hydraulic pump based on the first pump flow rate and the second pump flow rate calculated by the pump flow rate calculation unit.

6. A work machine comprising the control system according to claim 1.

7. A control method of controlling a work machine including a working unit and a plurality of hydraulic cylinders that drives the working unit, comprising:

discharging operating oil to be supplied to the plurality of hydraulic cylinders from a first hydraulic pump and a second hydraulic pump;

acquiring cylinder pressure data indicating a pressure of the operating oil of the plurality of hydraulic cylinders;

acquiring operation amount data of an operating device operated to drive the plurality of hydraulic cylinders;

calculating a first pump flow rate indicating a flow rate of the operating oil discharged from the first hydraulic pump and a second pump flow rate indicating a flow rate of the operating oil discharged from the second hydraulic pump in a splitting state in which a passage that connects the first hydraulic pump and the second hydraulic pump is closed by an opening and closing device based on the cylinder pressure data and the operation amount data;

controlling the first hydraulic pump and the second hydraulic pump in the splitting state based on the first pump flow rate and the second pump flow rate;

preventing an increase in a pressure of the operating oil using a relief valve; and

calculating a relief flow rate indicating a flow rate of the operating oil discharged via the relief valve based on a pump limit flow rate indicating a flow rate of the operating oil that the first hydraulic pump and the second hydraulic pump can discharge and a sum of distribution flow rates of the operating oil distributed to the plurality of hydraulic cylinders,

wherein the first hydraulic pump and the second hydraulic pump are controlled based on the relief flow rate.