EXCAVATOR AND METHOD OF CONTROLLING EXCAVATOR

• US 20200131734A1
• Filed: 12/26/2019
• Published: 04/30/2020
• Est. Priority Date: 07/05/2017
• Status: Active Grant

• Current Assignee: Sumitomo (S.H.I.) Construction Machinery Co., Ltd. (Sumitomo Heavy Industries Limited)
• Original Assignee: Sumitomo (S.H.I.) Construction Machinery Co., Ltd. (Sumitomo Heavy Industries Limited)
• Inventors: MAEDA, Norio, MAKINO, Masaki, TANAKA, Takumi
• Granted Patent: US 11,260,906 B2
• Time in Patent Office: Days
• CPC Class Codes: B62D 11/005 Hydraulic control systems
• CPC Class Codes: B62D 11/04 by means of separate power sources
• CPC Class Codes: E02F 9/2087 Control of vehicle steering for steering with hydraulic or pneumatic drives E02F9/225
• CPC Class Codes: E02F 9/225 Control of steering, e.g. for hydraulic motors driving the vehicle tracks steering in general B62D
• 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 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 2211/6658 Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode
• CPC Class Codes: F15B 2211/7058 Rotary output members
• CPC Class Codes: F15B 2211/75 Control of speed of the output member
• CPC Class Codes: F15B 2211/763 Control of torque of the output member by means of a variable capacity motor, i.e. by a secondary control on the motor
• CPC Class Codes: F16H 2061/6615 Imitating a stepped transmissions
• CPC Class Codes: F16H 61/40 hydrostatic
• CPC Class Codes: F16H 61/421 Motor capacity control by electro-hydraulic control means, e.g. using solenoid valves
• CPC Class Codes: F16H 61/47 for achieving a target output speed

Abstract

An excavator includes a lower travelling body; an upper turning body mounted on the lower travelling body; a hydraulic pump installed in the upper turning body; a travelling hydraulic motor that is a variable displacement type motor configured to move the lower travelling body by being driven by hydraulic oil discharged by the hydraulic pump; and a control device configured to control a motor capacity of the travelling hydraulic motor so as to be switchable between a plurality of levels. The control device switches the motor capacity to a low rotation setting upon detecting that an operation for changing a travelling direction of the lower travelling body is performed.

Claims

1. An excavator comprising:

a lower travelling body;

an upper turning body mounted on the lower travelling body;

a hydraulic pump installed in the upper turning body;

a travelling hydraulic motor that is a variable displacement type motor configured to move the lower travelling body by being driven by hydraulic oil discharged by the hydraulic pump; and

a control device configured to control a motor capacity of the travelling hydraulic motor so as to be switchable between a plurality of levels, wherein

the control device switches the motor capacity to a low rotation setting upon detecting that an operation for changing a travelling direction of the lower travelling body is performed.

2. The excavator according to claim 1, wherein

the travelling hydraulic motor includes a left travelling hydraulic motor and a right travelling hydraulic motor, and

the control device switches the motor capacity to the low rotation setting upon detecting that a difference between an operation amount of a left travelling operation device for operating the left travelling hydraulic motor and an operation amount of a right travelling operation device for operating the right travelling hydraulic motor exceeds a threshold value.

3. The excavator according to claim 1, wherein

the travelling hydraulic motor includes a left travelling hydraulic motor and a right travelling hydraulic motor, and

the control device switches the motor capacity to the low rotation setting upon detecting that a differential pressure between an operation pressure representing an operation amount of a left travelling operation device for operating the left travelling hydraulic motor and an operation pressure representing an operation amount of a right travelling operation device for operating the right travelling hydraulic motor exceeds a threshold value.

4. The excavator according to claim 1, wherein

the travelling hydraulic motor includes a left travelling hydraulic motor and a right travelling hydraulic motor, and

the control device switches the motor capacity to the low rotation setting upon detecting that a difference between an operation amount of a left travelling operation device for operating the left travelling hydraulic motor and an operation amount of a right travelling operation device for operating the right travelling hydraulic motor exceeds a first threshold value, and

after switching the motor capacity to the low rotation setting, the control device switches the motor capacity back to an original motor capacity upon detecting that the difference falls below a second threshold value that is lower than the first threshold value.

5. The excavator according to claim 1, wherein

the travelling hydraulic motor includes a left travelling hydraulic motor and a right travelling hydraulic motor, and

the control device switches the motor capacity to the low rotation setting upon detecting that the operation for changing the travelling direction of the lower travelling body is performed, in a case where a total value of an operation amount of a left travelling operation device for operating the left travelling hydraulic motor and an operation amount of a right travelling operation device for operating the right travelling hydraulic motor is less than a threshold value.

6. The excavator according to claim 1, wherein

the control device controls the motor capacity so as to be switchable between the low rotation setting and a high rotation setting, and

the control device switches the motor capacity to the low rotation setting upon detecting that the operation for changing the travelling direction of the lower travelling body is performed, in a case where the motor capacity is at the high rotation setting.

7. The excavator according to claim 1, wherein after the control device switches the motor capacity to the low rotation setting, the control device switches the motor capacity back to an original motor capacity upon detecting that the operation for changing the travelling direction of the lower travelling body has ended.

8. An excavator comprising:

a lower travelling body;

an upper turning body mounted on the lower travelling body;

a hydraulic pump installed in the upper turning body;

a travelling hydraulic motor that is a variable displacement type motor configured to move the lower travelling body by being driven by hydraulic oil discharged by the hydraulic pump; and

a control device configured to control a motor capacity of the travelling hydraulic motor so as to be switchable between a plurality of levels, wherein

the control device maintains the motor capacity at a low rotation setting upon detecting that the lower travelling body is curving on a flat ground.

9. The excavator according to claim 8, wherein the control device switches the motor capacity to a high rotation setting upon detecting that a travelling movement of the lower travelling body changes from curving to travelling straight forward.

10. The excavator according to claim 8, wherein the control device switches the motor capacity to the low rotation setting upon detecting that a tilt of a travelling operation device is small.

11. The excavator according to claim 8, wherein the control device determines that the lower travelling body is curving upon detecting that a difference between an operation amount of a left travelling operation device and an operation amount of a right travelling operation device exceeds a threshold value.

12. A method of controlling an excavator, the excavator including:

a lower travelling body;

an upper turning body mounted on the lower travelling body;

a hydraulic pump installed in the upper turning body;

a travelling hydraulic motor that is a variable displacement type motor configured to move the lower travelling body by being driven by hydraulic oil discharged by the hydraulic pump; and

a control device configured to control a motor capacity of the travelling hydraulic motor so as to be switchable between a plurality of levels, the method comprising;

maintaining, by the control device, the motor capacity at a low rotation setting upon detecting that the lower travelling body is curving on a flat ground.

13. The method of controlling the excavator according to claim 12, comprising:

switching, by the control device, the motor capacity to a high rotation setting upon detecting that a travelling movement of the lower travelling body changes from curving to travelling straight forward.

14. The method of controlling the excavator according to claim 12, comprising:

switching, by the control device, the motor capacity to the low rotation setting upon detecting that a tilt of a travelling operation device is small.

15. The method of controlling the excavator according to claim 12, comprising:

determining, by the control device, that the lower travelling body is curving upon detecting that a difference between an operation amount of a left travelling operation device and an operation amount of a right travelling operation device exceeds a threshold value.