Working machine

Patent metadata

Field	Value
Publication number	US-12454811-B2
Application number	US-202418743190-A
Country	US
Kind code	B2
Filing date	Jun 14, 2024
Priority date	Aug 24, 2023
Publication date	Oct 28, 2025
Grant date	Oct 28, 2025

Abstract

A working machine includes a working device, a hydraulic system including an actuator, and a hydraulic pump to supply a hydraulic fluid to the actuator, an electric device, a power generator to generate electric power to be directly or indirectly supplied to the electric device, a first cooling system to cool the electric device with a first cooling medium, and a second cooling system to cool the power generator with a second cooling medium. The first cooling system includes a first heat exchanger to cool the hydraulic fluid through heat exchange with the first cooling medium, a second heat exchanger to cool the second cooling medium through heat exchange with the first cooling medium, and a third heat exchanger to cool the first cooling medium through heat exchange with outside air to a temperature lower than temperatures before the heat exchange of the hydraulic fluid and the second cooling medium.

First claim

What is claimed is:

1. A working machine comprising:
a working device;
a hydraulic system including an actuator to actuate the working device, and a hydraulic pump to supply a hydraulic fluid to the actuator;
at least one electric device;
a power generator to generate electric power to be directly or indirectly supplied to the at least one electric device;
a first cooling system to cause a first cooling medium to circulate therethrough to cool the at least one electric device; and
a second cooling system to cause a second cooling medium to circulate therethrough to cool the power generator; wherein
the first cooling system includes:
a first heat exchanger to exchange heat between the hydraulic fluid and the first cooling medium to cool the hydraulic fluid;
a second heat exchanger to exchange heat between the first cooling medium and the second cooling medium to cool the second cooling medium; and
a third heat exchanger to exchange heat between the first cooling medium and outside air to cool the first cooling medium so that a temperature of the first cooling medium becomes lower than temperatures before the heat exchange of the hydraulic fluid and the second cooling medium.

2. The working machine according to claim 1 , wherein
the hydraulic system includes:
a hydraulic fluid tank to store the hydraulic fluid;
a primary system connecting the actuator and the hydraulic fluid tank via the hydraulic pump, to supply the hydraulic fluid stored in the hydraulic fluid tank to the actuator by driving the hydraulic pump; and
a secondary system connecting the actuator and the hydraulic fluid tank, to return the hydraulic fluid from the actuator to the hydraulic fluid tank; and

the first heat exchanger is included in the secondary system, to exchange heat between the hydraulic fluid flowing through the secondary system and the first cooling medium.

3. The working machine according to claim 2 , wherein
the hydraulic system includes:
a temperature sensor to measure a temperature of the hydraulic fluid in the hydraulic fluid tank; and
a bypass connecting a first position located upstream of the first heat exchanger on the secondary system and a second position located downstream of the first heat exchanger, the bypass including a throttle valve to adjust a flow rate of the hydraulic fluid so that a measurement result of the temperature sensor becomes an appropriate temperature of the hydraulic fluid.

4. The working machine according to claim 1 , wherein
the at least one electric device includes a plurality of electric devices; and
the plurality of electric devices are included in the first cooling system and cooled in ascending order of heat resistance and heat generation temperature during operation from an upstream side to a downstream side in a flow direction of the first cooling medium.

5. The working machine according to claim 2 , wherein
the at least one electric device includes a plurality of electric devices; and
the plurality of electric devices are included in the first cooling system and cooled in ascending order of heat resistance and heat generation temperature during operation from an upstream side to a downstream side in a flow direction of the first cooling medium.

6. The working machine according to claim 3 , wherein
the at least one electric device includes a plurality of electric devices; and
the plurality of electric devices are included in the first cooling system and cooled in ascending order of heat resistance and heat generation temperature during operation from an upstream side to a downstream side in a flow direction of the first cooling medium.

7. The working machine according to claim 4 , wherein
the plurality of electric devices include:
an electric motor; and
an inverter to drive the electric motor;

the electric motor and the inverter are included in the first cooling system; and
the inverter is located upstream of the electric motor in the flow direction of the first cooling medium.

8. The working machine according to claim 1 , wherein
the at least one electric device includes a power generator inverter to drive the power generator; and
the power generator inverter is included in the first cooling system.

9. The working machine according to claim 2 , wherein
the at least one electric device includes a power generator inverter to drive the power generator; and
the power generator inverter is included in the first cooling system.

10. The working machine according to claim 3 , wherein
the at least one electric device includes a power generator inverter to drive the power generator; and
the power generator inverter is included in the first cooling system.

11. The working machine according to claim 1 , wherein the second cooling medium is a liquid having a specific heat smaller than a specific heat of the first cooling medium and a boiling point higher than a boiling point of the first cooling medium.

12. The working machine according to claim 11 , wherein
the first cooling medium is water; and
the second cooling medium is oil.

13. The working machine according to claim 1 , wherein
the first heat exchanger is located downstream of the second heat exchanger and upstream of the third heat exchanger; and
the second heat exchanger is located downstream of the electric device.

14. The working machine according to claim 2 , wherein
the first heat exchanger is located downstream of the second heat exchanger and upstream of the third heat exchanger; and
the second heat exchanger is located downstream of the electric device.

15. The working machine according to claim 3 , wherein
the first heat exchanger is located downstream of the second heat exchanger and upstream of the third heat exchanger; and
the second heat exchanger is located downstream of the electric device.

16. The working machine according to claim 4 , wherein
the first heat exchanger is located downstream of the second heat exchanger and upstream of the third heat exchanger; and
the second heat exchanger is located downstream of the electric device.

17. The working machine according to claim 1 , further comprising:
an internal combustion engine to drive the power generator; and
a third cooling system to cause a third cooling medium to circulate therethrough to cool the internal combustion engine; wherein
the third cooling system includes a fourth heat exchanger to exchange heat between the third cooling medium and outside air, the fourth heat exchanger being provided in parallel with the third heat exchanger; and
at least one of the first cooling system and the third cooling system includes a cooling fan to send the outside air toward the third heat exchanger and the fourth heat exchanger.

18. The working machine according to claim 17 , wherein the power generator is a motor generator that includes an output shaft to transmit drive to the hydraulic pump, and that is switchable between a power generation state in which the motor generator generates electric power by receiving a drive of the internal combustion engine and a drive state in which the motor generator is driven to rotate by receiving supply of electric power, and the power generator drives the hydraulic pump via the output shaft in the power generation state and the drive state.

19. The working machine according to claim 1 , wherein
each of the first cooling medium and the second cooling medium is a liquid;
the first heat exchanger and the second heat exchanger are liquid-cooled heat exchangers to exchange heat between

Assignees

• Kubota Kk

Inventors

• Yagyu Sumio
• Ii Tsunehiro

Classifications

• E02F9/0866

  Engine compartment, e.g. heat exchangers, exhaust filters, cooling devices, silencers, mufflers, position of hydraulic pumps in the engine compartment · CPC title

• E02F9/226

  Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating · CPC title

• F01P2050/24

  Hybrid vehicles · CPC title

• E02F9/2075 Primary

  of the hybrid type (for vehicles in general B60W20/00) · CPC title