WO2021190786A1

WO2021190786A1 - Thermal management of an electric machine or vehicle

Info

Publication number: WO2021190786A1
Application number: PCT/EP2021/025105
Authority: WO
Inventors: Robert Nicholas Harper
Original assignee: Caterpillar Sarl
Priority date: 2020-03-26
Filing date: 2021-03-16
Publication date: 2021-09-30
Also published as: GB2591310A; GB202004398D0

Abstract

A machine comprises a motor assembly having an output shaft configured either to effect machine propulsion or to actuate a machine tool. The machine further comprises a controller configured to control the motor assembly and a battery configured to store electrical energy for use by the motor assembly. The machine further comprises a thermal circuit for transfer of thermal energy, the thermal circuit comprising: a pump configured to pump liquid within the thermal circuit; a radiator configured to radiate thermal energy to an exterior of the machine; and a motor conduit for transfer of thermal energy between the motor assembly and the thermal circuit. The motor assembly comprises a dual motor assembly that comprises a first motor and a second motor. The controller is configured to control the first motor to act against the second motor in response to a call for a rise in temperature of the thermal circuit.

Description

THERMAL MANAGEMENT OF AN ELECTRIC MACHINE OR VEHICLE Technical Field

The disclosure relates to thermal management of electric machines and vehicles.

Background

In vehicles and work machines that have an internal combustion engine, the internal combustion engine may serve not only its primary purpose of generating kinetic energy but also a secondary purpose of generating thermal energy. The thermal energy may be used for warming a thermal circuit that is used for heating components of the machine which may have a call for heat. One such example would be cab heating. In particular, thermal energy generated by the internal combustion engine and transferred to the thermal heating circuit may, in part, be circulated to a heat exchanger configured to supply thermal energy into the cab.

In electric machines that have no internal combustion engine thermal energy may be required for a variety of purposes. Such purposes may include not only cab heating but also warming batteries that supply electric motors of the electric machine and in machines that have hydraulically actuated implements, warming the hydraulic fluid. Other requirements for thermal energy may also apply.

It is known to provide a dedicated electric heater to provide thermal energy for various purposes. For example, it is known to provide a solid state electric heater for providing cab heating. This involves cost and occupies space that might otherwise accommodate other features.

Summary of the Disclosure Against this background there is provided a machine comprising: a motor assembly having an output shaft configured either to effect machine propulsion or to actuate a machine tool; a controller configured to control the motor assembly; a battery configured to store electrical energy for use by the motor assembly; a thermal circuit for transfer of thermal energy, the thermal circuit comprising: a pump configured to pump liquid within the thermal circuit; a radiator configured to radiate thermal energy to an exterior of the machine; and a motor conduit for transfer of thermal energy between the motor assembly and the thermal circuit; wherein the motor assembly comprises a dual motor assembly that comprises a first motor and a second motor; and the controller is configured to control the first motor to act against the second motor in response to a call for a rise in temperature of the thermal circuit.

In this way, it is possible to use a motor assembly that is already present on the machine, either for machine propulsion or for actuation of a machine tool, also to provide thermal energy when required. The first motor and the second motor are used to drive an output shaft and may or may not be part of a single motor assembly package.

Brief Description of the Drawings Figure 1 shows a schematic representation of a wheel loader to which the apparatus and method of the present disclosure may be applied; Figure 2 shows a schematic representation of a thermal circuit in accordance with the present disclosure which may be applied to an electric machine, such as the wheel loader of Figure 1;

Figure 3 shows a schematic representation of a dual motor for use in the apparatus and method of the present disclosure; and

Figure 4 shows a schematic representation of an alternative thermal circuit that includes additional features and functionality compared with the thermal circuit 151 of Figure 2.

Detailed Description

Figure 1 shows an electrically powered machine, specifically a wheel loader 100, which may use one or more electric traction motors (not shown in Figure 1) to provide machine propulsion via wheels 110. The wheel loader 100 may have a loader assembly 130 having a connector portion 131 configured to hold a loading implement (not shown in Figure 1) such as a bucket or forks. The loader assembly 130 and loader implement may be hydraulically driven by one or more hydraulic motors. Electrical energy for use by the one or more traction motors and the one or more hydraulic motors may be stored in a battery (not shown in Figure 1).

Figure 2 shows a highly schematic representation of a thermal circuit 150 of the machine for transfer of thermal energy around the machine 100.

The thermal circuit 150 comprises a pump 152 configured to pump liquid around the thermal circuit 150 and a radiator assembly 154 configured to release thermal energy from the thermal circuit 150 to an exterior of the machine 100. The radiator assembly 154 may comprise a radiator conduit 156, a radiator 153 and a radiator fan 155 configured to accelerate dissipation of thermal energy from the radiator 153. The radiator assembly 154 may also comprise a header tank 157 configured to supply liquid to the radiator 153 via a supply line 158 and configured to receive liquid from the thermal circuit 150 via a return line 159.

The thermal circuit 150 may comprise a primary motor conduit 202 for transfer of thermal energy between a dual motor assembly 250 and the thermal circuit 150. The primary motor conduit 202 may comprise a valve 204 to restrict flow in the primary motor conduit 202.

The thermal circuit 150 further comprises a heat exchanger conduit 182 including a heat exchanger 180. The heat exchanger conduit 182 may be parallel to the radiator conduit 156 so as to provide an alternative path to the radiator conduit 156. In a cab heating mode, the heat exchanger 180 may be configured to feed heat into the cab of the machine 100.

A multiway valve 190 may be configured to control flow in the radiator conduit 156 and in the heat exchanger conduit 182. Alternatively, separate valves may be provided to control flow in each of the radiator conduit 156 and the heat exchanger conduit 182. Where there is no call for heat from the heat exchanger 180 it may be that all of the flow is directed to the radiator conduit 156.

By controlling the pump 152, the radiator fan 155, and the multiway valve 190, control of liquid in the thermal circuit 150 may be controlled to transfer thermal energy around the thermal circuit 150 as required.

Accordingly, the thermal circuit 150 provides functionality for the transfer of thermal energy around the machine 100. Excess thermal energy may be drawn away from the dual motor assembly 250. Excess thermal energy may be transferred out of the machine via the radiator 153. Furthermore, thermal energy may be supplied to a cab of the machine 100 via the heat exchanger 180.

The dual motor assembly 250 is shown in more detail in Figure 3. Referring to Figure 3, the dual motor assembly 250 may have an output shaft 210 and may comprise a first motor 300 and a second motor 400 each connected to the output shaft 210. The dual motor assembly 250 may be configured either to effect machine propulsion or to actuate a machine tool. A first invertor may be associated with the first motor 300 and a second invertor may be associated with the second motor 400.

The first motor 300 may comprise a first motor stator 310, a first motor rotor 320, and a first electrical current supply connection 330 which may provide a three- phase current supply. Similarly, the second motor 400 may comprise a second motor stator 410 and a second motor rotor 420 and a second electrical current supply connection 430 which may provide a three-phase current supply. The first motor rotor 320 and the second motor rotor 420 may be connected directly or indirectly to the output shaft 210 of the dual motor assembly 250.

Where the desired output from the dual motor assembly 250 is kinetic energy in the form of rotational kinetic energy of the output shaft 210, it is possible to use only one of the two motors 300, 400 or to use both of the two motors 300, 400 acting together. This may be achieved by having the three phase supply to the first motor 300 in phase with the three phase supply to the second motor 400.

Having a dual motor assembly 250 comprising two motors 300, 400 in place of a single motor may assist in providing additional torque when required and may allow a differently dimensioned motor assembly than one comprising only a single motor capable of providing the additional torque.

Having a dual motor assembly 250 comprising two motors 300, 400 also allows for the possibility of generating thermal energy by running the first motor 300 against the second motor 400.

The dual motor assembly 250 may further comprise a motor duct 550 that forms a part of a thermal circuit 150 of the machine 100 for transfer of thermal energy. The motor duct 550 may have a first end 551 which may serve as an inlet and a second end 552 which may serve as an outlet. The primary motor conduit 202 of Figure 2 may comprise the motor duct 550 of Figure 3. In this way, thermal energy may be transferred between the dual motor assembly 250 and the thermal circuit 500 via the motor duct 550. The motor duct 550 may have a first end 551 and a second end 552 and the thermal circuit 500 may be configured such that liquid flows from the first end 551 to the second end 552 in such a way that in between the first end 551 and the second end 552 there is an efficient transfer of thermal energy between the dual motor assembly 250 and the liquid in the motor duct 550 of the thermal circuit 500. In use, the dual motor assembly 250 may be controlled in a variety of modes. Control may be effected by a controller.

In short, a decision on how to operate each of the first and second motors of the dual motor assembly 250 may be based on: (a) demand for output shaft rotation; and

(b) demand for a rise in temperature of the thermal circuit.

In a first mode, there may be call for traction from the dual motor assembly but no call for generation of thermal energy from the dual motor assembly. In the first mode, a first amount of electrical energy (Xi) may provide to the first invertor to effect movement of the first motor 300 in a first direction. Optionally, a second amount of electrical energy (X2) may be provided to the second invertor to effect movement of the second motor 400 also in the first direction. In this way, the effort provided by both first motor 300 and the second motor 400 (Xi + X2) effects rotation of the output shaft 210 in the first direction.

In a second mode, there may be no call for traction from the dual motor assembly 250 but a call for generation of thermal energy from the dual motor assembly 250. In the second mode, a first amount of electrical energy (Y) may be provided to the first invertor to generate torque in the first motor 300 in a first direction and a second amount of electrical energy (Y) equal to the first amount of electrical energy may be provided to the second inventor to generate torque in the second motor 400 in a second direction opposite to the first direction such that the output shaft 210 remains substantially stationary and the first and second amounts of electrical energy are converted to thermal energy.

In a third mode, there may be a call for both traction and thermal energy from the dual motor assembly 250. In the third mode, a first quantity of electrical energy (Zi+ Z2) may provide to the first invertor to generate torque in the first motor 300 in a first direction and second quantity of electrical energy (Zi) may be provided to the second invertor to generate torque in the second motor 400 in a second direction opposite to the first direction. The first quantity of electrical energy (Zi+ Z2) may be greater than the second quantity of electrical energy (Zi). In this way, thermal energy may be generated from the combination the second quantity of electrical energy and a first portion of the first quantity of electrical energy which acts against the second quantity of electrical energy (= 2 x Zi). At the same time, the second portion of the first quantity of electrical energy equal to the first quantity of electrical energy minus the first portion of the first quantity of electrical energy (= Z2) may be used to effect movement of the output shaft in the first direction.

Figure 4 shows a schematic representation of an alternative thermal circuit 151 that includes additional features and functionality compared with the thermal circuit 150 of Figure 2.

In addition to the features of the thermal circuit 150 shown in Figure 2, the alternative thermal circuit 151 may also comprise one or more of the following additional features.

The alternative thermal circuit 151 may also comprise a secondary motor conduit 207 for transfer of thermal energy between a secondary motor assembly 205 and the thermal circuit 150. The secondary motor conduit 207 may comprise a secondary motor conduit valve 209 configured to control flow in the secondary motor conduit 207. The secondary motor assembly 205 may be a dual motor assembly of a similar architecture to the dual motor assembly 250 shown in Figure 3 or may be any other type of motor assembly suitable for the purpose. The alternative thermal circuit 151 may also comprise a battery charger conduit 172 for transfer of thermal energy between a battery charger 170 and the thermal circuit 150. The battery charger conduit 172 may comprise a battery charger conduit valve 174 configured to control flow in the battery charger conduit 172.

The alternative thermal circuit 151 may also comprise a battery conduit 162 for transfer of thermal energy between the battery 160 and the thermal circuit 150. The battery conduit 162 may comprise a battery conduit valve 164 configured to control flow in the battery conduit 162. In a battery warm up mode, thermal energy may be transferred from the thermal circuit 150 to the battery 160. In a battery charger cooling mode, thermal energy may be transferred from the battery 160 to the thermal circuit 150.

In this way, excess thermal energy may be drawn away not only from the dual motor assembly 250, but also from the secondary motor assembly 205, the battery charger 170 and the battery 160 as appropriate.

Furthermore, it may be that thermal energy may be supplied to, for example, the battery 160 where appropriate.

The secondary motor assembly 205 of Figure 4 may be a dual motor assembly 250 as shown in Figure 3.

It may be that the dual motor assembly 250, which can provide either or both of a kinetic and a thermal output, is configured such that its kinetic output is for the provision of machine propulsion. Alternatively, it may be that the dual motor assembly 250 is configured such that its kinetic output is for the provision of hydraulic flow for operation of a hydraulically operated work tool such as a loader or excavator arm.

The disclosure discusses various valves for controlling liquid flow in the thermal circuit 150 and the alternative thermal circuit 151. It is not necessarily the case that all valves are required. Furthermore, it is not necessarily the case that all valves are actively controlled. For example, some of the valves may be backpressure valves that provide a fixed amount of resistance to flow.

Industrial Applicability

In the arrangement of the present disclosure, it is possible to use a dual motor assembly 250 whose primary purpose is to provide traction or to effect movement of a hydraulic work tool for a secondary purpose of providing thermal energy to the thermal circuit 150. Moreover, it is possible to control the dual motor assembly 250 in such a way as to provide the primary and secondary purposes either separately or simultaneously.

Claims

1. A machine comprising: a motor assembly having an output shaft configured either to effect machine propulsion or to actuate a machine tool; a controller configured to control the motor assembly; a battery configured to store electrical energy for use by the motor assembly; a thermal circuit for transfer of thermal energy, the thermal circuit comprising: a pump configured to pump liquid within the thermal circuit; a radiator configured to radiate thermal energy to an exterior of the machine; and a motor conduit for transfer of thermal energy between the motor assembly and the thermal circuit; wherein the motor assembly comprises a dual motor assembly that comprises a first motor and a second motor; and the controller is configured to control the first motor to act against the second motor in response to a call for a rise in temperature of the thermal circuit.

2. The machine of claim 1 wherein the thermal circuit further comprises a heat exchanger configured to release heat into a cab of the machine.

3. The machine of claim 2 wherein the thermal circuit comprises a heat exchanger conduit and a radiator conduit parallel to the heat exchanger conduit, and wherein distribution of flow between the heat exchanger conduit and the radiator conduit is controlled by a heat exchanger conduit valve.

4. The machine of any preceding claim wherein the thermal circuit further comprises: a battery conduit for transfer of thermal energy between the battery and the thermal circuit; a battery bypass conduit; and a battery conduit valve configured to control liquid flow in the battery conduit.

5. The machine of any preceding claim further comprising a battery charger, wherein the thermal circuit further comprises: a battery charger conduit; and a battery charger conduit valve configured to control liquid flow in the battery charger conduit.

6. The machine of claim 2 or any claim dependent on claim 2, the machine having a cab heating mode in which thermal energy is transferred from the thermal circuit to the heat exchanger for release into the cab.

7. The machine of any preceding claim, the machine having a battery warm up mode in which thermal energy is transferred from the thermal circuit to the battery.

8. The machine of claim 5 or any claim dependent on claim 5, the machine having a battery charger cooling mode in which thermal energy is transferred from the battery charger to the thermal circuit.

9. The machine of any preceding claim wherein the first motor comprises a first invertor and the second motor comprises a second invertor.

10. The machine of claim 9 wherein the controller is configured to control supply of electrical energy to each of the first and second invertors in accordance with:

(a) demand for output shaft rotation; and

(b) demand for a rise in temperature of the thermal circuit.

11. The machine of claim 9 or claim 10 wherein the dual motor assembly is operable in a first mode in which electrical energy is provided to the first invertor to effect movement of the first motor in a first direction and electrical energy is provided to the second invertor to effect movement of the second motor in the first direction such that the output shaft moves in the first direction.

12. The machine of any of claims 9 to 11 wherein the dual motor assembly is operable in a second mode in which a first amount of electrical energy is provided to the first invertor and a second amount of electrical energy is provided to the second inventor, wherein the first and second amounts of energy are equal and opposite such that the output shaft remains substantially stationary and the first and second amounts of electrical energy are converted to thermal energy.

13. The machine of any of claims 9 to 12 wherein the dual motor assembly is operable in a third mode in which: a first quantity of electrical energy is provided to the first invertor to generate torque in the first motor in a first direction and second quantity of electrical energy is provided to the second invertor to generate torque in the second motor in a second direction opposite to the first direction, wherein the first quantity of electrical energy is greater than the second quantity of electrical energy; such that thermal energy is generated from the combination the second quantity of electrical energy and a first portion of the first quantity of electrical energy which acts against the second quantity of electrical energy; and such that a second portion of the first quantity of electrical energy equal to the first quantity of electrical energy minus the first portion of the first quantity of electrical energy is used to effect movement of the output shaft in the first direction.

14. The machine of any of claims 9 to 12 wherein the dual motor assembly is operable in a third mode in which: a first quantity of electrical energy is provided to the first invertor to generate torque in the first motor in a first direction and second quantity of electrical energy is provided to the second invertor to generate torque in the second motor, wherein the first quantity of electrical energy is greater than the second quantity of electrical energy such that the output shaft moves in the first direction; and wherein either:

(a) the second quantity of electrical energy is provided to the second invertor to generate torque in the second motor in the first direction, such that the motors are run at different loads such that thermal energy is thereby generated; or

(b) the second quantity of electrical energy is provided to the second invertor to generate torque in the second motor in a second direction opposite to the first direction such that thermal energy is thereby generated.

15. The machine of any preceding claim wherein: either the dual motor assembly is configured to effect machine propulsion and, optionally, wherein a second dual motor assembly is configured to actuate a machine tool; or the dual motor assembly is configured to actuate a machine tool and, optionally, wherein a second dual motor assembly is configured to effect machine propulsion.