Control system, work machine, and control method

Patent metadata

Field	Value
Publication number	US-10344781-B2
Application number	US-201615501269-A
Country	US
Kind code	B2
Filing date	Jul 29, 2016
Priority date	Jul 29, 2016
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A control system for controlling a work machine including a working unit including elements and actuators that drives the elements includes: a first hydraulic pump and a second hydraulic pump each of which supplies operating oil to at least one of the actuators; and a control device that calculates a distribution flow rate of operating oil distributed to each of the actuators based on an operating state of the working unit and switches, based on the calculated distribution flow rate, between a first state in which the operating oil supplied from both the first hydraulic pump and the second hydraulic pump is supplied to the actuators and a second state in which the actuator to which the operating oil is supplied from the first hydraulic pump is different from the actuator to which the operating oil is supplied from the second hydraulic pump.

First claim

The invention claimed is:

1. A control system for controlling a work machine including a working unit including a plurality of elements and a plurality of actuators that drives the plurality of elements, comprising:
a first hydraulic pump and a second hydraulic pump each of which supplies operating oil to at least one of the actuators;
a control device that calculates a distribution flow rate of operating oil distributed to each of the actuators based on an operating state of the working unit and switches, based on the calculated distribution flow rate, between a first state in which the operating oil supplied from both the first hydraulic pump and the second hydraulic pump is supplied to the actuators and a second state in which the actuator to which the operating oil is supplied from the first hydraulic pump is different from the actuator to which the operating oil is supplied from the second hydraulic pump,
a passage that connects the first hydraulic pump and the second hydraulic pump; and
an opening and closing device that is provided in the passage to open and close the passage, wherein
in a state in which the passage is closed, the first hydraulic pump supplies operating oil to a first actuator group to which at least one of the actuators belongs, and the second hydraulic pump supplies operating oil to a second actuator group to which at least one of the actuators different from the actuator belonging to the first actuator group belongs,
the control device switches between the first state and the second state by operating the opening and closing device based on the distribution flow rate, and
when the calculated distribution flow rate increases with time, the control device operates the opening and closing device using a corrected distribution flow rate obtained by decreasing an increase over time in the calculated distribution flow rate.

2. The control system according to claim 1 , wherein the control device calculates the distribution flow rate based on the operating state of the working unit and a load of the actuator.

3. The control system according to claim 1 , wherein the control device operates the opening and closing device based on a comparison result between the distribution flow rate and a threshold determined based on a flow rate of operating oil that one first hydraulic pump can supply and a flow rate of operating oil that one second hydraulic pump can supply.

4. The control system according to claim 1 , wherein when determining whether the opening and closing device is to be operated, the control device switches whether the corrected distribution flow rate or the distribution flow rate is to be used depending on the operating state.

5. The control system according to claim 1 , wherein
the plurality of elements includes a bucket, an arm connected to the bucket, and a boom connected to the arm,
the plurality of actuators includes a bucket cylinder that operates the bucket, an arm cylinder that operates the arm, and a boom cylinder that operates the boom, and
the bucket cylinder and the arm cylinder belong to the first actuator group, and the boom cylinder belongs to the second actuator group.

6. The control system according to claim 1 , wherein
the work machine has a swing structure that supports the working unit, and
the swing structure is driven by an actuator that does not belong to the first actuator group and the second actuator group.

7. The control system according to claim 1 , further comprising:
a first detector that detects a largest load pressure of the actuators that belong to the first actuator group;
a first oil passage that guides the largest load pressure detected by the first detector to a first hydraulic pump control device that operates the first hydraulic pump;
a second detector that detects a largest load pressure of the actuators that belong to the second actuator group;
a second oil passage that guides the largest load pressure detected by the second detector to a second hydraulic pump control device that operates the second hydraulic pump; and
a switching valve that switches between a connection and a disconnection of the first detector and the second detector and switches between a connection and a disconnection of the first oil passage and the second oil passage, wherein
in an intermediate state between the connection and the disconnection, the switching valve connects the first detector and the first oil passage in a state in which no throttle is provided, connects the first detector and the second detector in a state in which a throttle is provided, and connects the first oil passage and the second oil passage in a state in which a throttle is provided.

8. The control system according to claim 7 , wherein
the control device holds the switching valve in the intermediate state after the control device switches the switching valve from the disconnection state to the intermediate state,
when a pressure difference between a pressure of the operating oil discharged from the first hydraulic pump and a pressure of the operating oil discharged from the second hydraulic pump is equal to or smaller than a predetermined threshold, the control device stops holding the switching valve in the intermediate state and changes the switching valve to the connection state, and
the control device opens the opening and closing device after the switching valve enters into the connection state.

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

10. A control method of controlling a work machine including a first hydraulic pump and a second hydraulic pump each of which supplies operating oil to at least one of a plurality of actuators that drives a plurality of elements that form the working unit, a control device, a passage that connects the first hydraulic pump and the second hydraulic pump; and an opening and closing device that is provided in the passage to open and close the passage, the control method comprising:
calculating a distribution flow rate of the operating oil distributed to each of the actuators based on an operating state of the working unit; and
switching, based on the calculated distribution flow rate, between a first state in which the operating oil supplied from both the first hydraulic pump and the second hydraulic pump is supplied to the actuators and a second state in which the actuator to which the operating oil is supplied from the first hydraulic pump is different from the actuator to which the operating oil is supplied from the second hydraulic pump,
in a state in which the passage is closed, supplying, by the first hydraulic pump, operating oil to a first actuator group to which at least one of the actuators belongs, and supplying, by the second hydraulic pump, operating oil to a second actuator group to which at least one of the actuators different from the actuator belonging to the first actuator group belongs,
switching, by the control device, between the first state and the second state by operating the opening and closing device based on the distribution flow rate, and
when the calculated distribution flow rate increases with time, operating, by the control device, the opening and closing device using a corrected distribution flow rate obtained by decreasing an increase over time in the calculated distribution flow rate.

Assignees

• Komatsu Mfg Co Ltd

Inventors

• Kamoshita Yuta
• Kawaguchi Tadashi
• Akiyama Teruo
• Oshima Kenji
• Saito Koji
• Iida Noboru

Classifications

• F15B13/06 Primary

  for use with two or more servomotors · CPC title

• F15B2211/30595

  with additional valves between the groups of valves for multiple output members · CPC title

• F15B11/02

  Systems essentially incorporating special features for controlling the speed or actuating force of an output member · CPC title

• E02F3/422

  Drive systems for bucket-arms, front-end loaders, dumpers or the like · CPC title

• E02F9/2221 Primary

  Control of flow rate; Load sensing arrangements (E02F9/2203 take precedence over E02F9/2221) · CPC title