ELECTRIC MOTOR AND DRIVE SYSTEM FOR HEAT TRANSFER

Abstract

Electric motor including: a rotor whose rotating shaft extends along an axis of extension, a stator disposed around the rotor, a front bearing and a rear bearing configured to be assembled by forming an internal cavity in which the rotor and the stator are housed, the front bearing comprising a cylindrical portion extending along the axis of extension, and a lid having bell shape that completely covers the rear bearing and at least the cylindrical portion of the front bearing, the lid comprising an internal chamber which extends at least partly around the internal cavity, a heat-transfer fluid inlet and a heat-transfer fluid outlet fluidly connected to the internal chamber so as to allow a heat-transfer fluid to circulate in the internal chamber.

Claims

1. An electric motor comprising: a rotor whose rotating shaft extends along an axis of extension, a stator disposed around the rotor, a front bearing and a rear bearing configured to be assembled by forming an internal cavity in which the rotor and the stator are housed, the front bearing comprising a cylindrical portion extending along the axis of extension, and a lid having a bell shape that completely covers the rear bearing and at least the cylindrical portion of the front bearing, the lid comprising an internal chamber which extends at least partly around the internal cavity, a heat-transfer fluid inlet and a heat-transfer fluid outlet fluidly connected to the internal chamber so as to allow the circulation of a heat-transfer fluid in the internal chamber.

2. The electric motor according to claim 1, wherein the lid is configured to form with the cylindrical portion at least one internal channel extending at least partly around the internal cavity and configured for the circulation of a refrigerant liquid.

3. The electric motor according to claim 2, wherein the internal channel has a substantially cylindrical shape whose longitudinal axis extends coaxially with the axis of extension.

4. The electric motor according to claim 1, wherein the heat-transfer fluid is a lubricating oil such as a heat engine oil or a gearbox oil.

5. The electric motor according to claim 1, wherein the internal chamber is cylindrical.

6. The electric motor according to claim 2, wherein the internal chamber and the internal channel are coaxial.

7. A drive system comprising a circulation circuit for a heat-transfer fluid including successively: a heat engine, a first pump, and an electric motor comprising a rotor whose rotating shaft extends along an axis of extension, a stator disposed around the rotor, a front bearing and a rear bearing configured to be assembled by forming an internal cavity in which the rotor and the stator are housed, the front bearing comprising a cylindrical portion extending along the axis of extension, and a lid having a bell shape that completely covers the rear bearing and at least the cylindrical portion of the front bearing, the lid comprising an internal chamber which extends at least partly around the internal cavity, a heat-transfer fluid inlet and a heat-transfer fluid outlet fluidly connected to the internal chamber so as to allow the circulation of a heat-transfer fluid in the internal chamber, fluidly connected in series, the first pump being configured to cause the circulation of the heat-transfer fluid in the circulation circuit from the internal chamber of the electric motor to the heat engine so as to perform a heat transfer from the electric motor to the heat engine in order to transfer heat energy from the electric motor to the heat engine thanks to the heat-transfer fluid.

8. The drive system according to claim 7, comprising a temperature sensor configured to measure the temperature of the heat-transfer fluid at the inlet of the heat engine, and wherein the first pump comprises a controller configured to communicate with the temperature sensor, and pilot: the starting of the first pump so as to cause circulation of the heat-transfer fluid in the internal chamber when the temperature of the heat-transfer fluid measured by the temperature sensor is lower than a predetermined threshold temperature value so as to heat the heat engine, and the stopping of the first pump so as to stop the circulation of the heat-transfer fluid in the internal chamber when the temperature of the heat-transfer fluid measured by the temperature sensor is greater than a predetermined threshold temperature value.

9. The drive system according to claim 7, comprising a refrigerant circuit for the circulation of a refrigerant liquid including successively: the electric motor, wherein the lid is configured to form with the cylindrical portion at least one internal channel extending at least partly around the internal cavity and configured for the circulation of a refrigerant liquid, a second pump, and a heat exchanger configured to cool a refrigerant fluid, fluidly connected in series, the second pump being configured to cause the circulation of the refrigerant liquid in the refrigerant circuit from the heat exchanger to the internal channel in order to cool the electric motor.

10. The drive system according to claim 9, wherein the refrigerant circuit and the heat-transfer fluid circulation circuit are configured so that the circulation direction of the refrigerant liquid is opposite to the circulation direction of the heat-transfer fluid.

11. The electric motor according to claim 2, wherein the heat-transfer fluid is a lubricating oil such as a heat engine oil or a gearbox oil.

12. The electric motor according to claim 11, wherein the internal chamber is cylindrical.

13. The electric motor according to claim 12, wherein the internal chamber and the internal channel are coaxial.

14. The electric motor according to claim 3, wherein the heat-transfer fluid is a lubricating oil such as a heat engine oil or a gearbox oil.

15. The electric motor according to claim 14, wherein the internal chamber is cylindrical.

16. The electric motor according to claim 15, wherein the internal chamber and the internal channel are coaxial.

17. The drive system according to claim 8, comprising a refrigerant circuit for the circulation of a refrigerant liquid including successively: the electric motor, wherein the lid is configured to form with the cylindrical portion at least one internal channel extending at least partly around the internal cavity and configured for the circulation of a refrigerant liquid, a second pump, and a heat exchanger configured to cool a refrigerant fluid, fluidly connected in series, the second pump being configured to cause the circulation of the refrigerant liquid in the refrigerant circuit from the heat exchanger to the internal channel in order to cool the electric motor.

18. The drive system according to claim 17, wherein the refrigerant circuit and the heat-transfer fluid circulation circuit are configured so that the circulation direction of the refrigerant liquid is opposite to the circulation direction of the heat-transfer fluid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The invention will be better understood on reading the following non-limiting description, made with reference to the appended figures.

[0060] FIG. 1 is a longitudinal section view of an electric motor according to a particular embodiment of the invention,

[0061] FIG. 2 is a longitudinal section view of the electric motor of FIG. 1.

[0062] FIG. 3 is a cross-sectional view of the electric motor of FIG. 1.

[0063] FIG. 4 is a perspective view of the electric motor of FIG. 1.

[0064] FIG. 5 is a schematic view of a drive system comprising the electric motor of FIG. 1 and a heat engine.

DETAILED DESCRIPTION

[0065] As illustrated in FIGS. 1 to 3, the electric motor 100 of the invention comprises a rotor 1 whose rotation shaft 3 extends along an axis of extension X and a stator 2 disposed around the rotor 1. It also comprises a front bearing 4 comprising a cylindrical portion 5 extending along the axis of extension X and a rear bearing 6, having the overall shape of a disc, assembled together to form an internal cavity 7 allowing to house the rotor 1 and the stator 2. According to an arrangement not visible in the Figures, the front bearing 4 is made of aluminum and the rear bearing 6 is made of steel.

[0066] The electric motor 100 further comprises a lid 8 having a bell shape, made of plastic material. The lid 8 covers the entire rear bearing 6 and at least the cylindrical portion 5 of the front bearing 4 (illustrated in FIGS. 1 to 4). The lid 8 comprises an internal chamber 10 which extends around the internal cavity 7. The lid 8 is provided with a heat-transfer fluid inlet 9 and a heat-transfer fluid outlet 11 fluidly connected to the internal chamber 10 so as to a allow circulation of a heat-transfer fluid in the internal chamber 10 (illustrated in FIGS. 2 and 3).

[0067] According to an arrangement represented in FIGS. 1 to 3, the lid 8 is configured to form with the cylindrical portion 5 of the front bearing 4 an internal channel 12 extending at least partly around the internal cavity 7. The lid 8 also comprises a refrigerant liquid inlet pipe 13 and a refrigerant liquid outlet pipe 14 fluidly connected to the internal channel 12. Thus, the lid 8 is configured for the circulation of a refrigerant liquid in the internal channel 12, allowing the cooling of the internal cavity 7 and of the stator 2.

[0068] As visible in FIGS. 1 and 2, the internal channel 12 has a substantially cylindrical shape whose longitudinal axis extends coaxially to the axis of extension X as well as the internal chamber 10 which is cylindrical. The internal chamber 10 and the internal channel 12 are coaxial, the internal chamber 10 surrounding the internal channel 12 so as to facilitate thermal exchange.

[0069] FIG. 5 illustrates another aspect of the invention relating to a drive system 200 comprising a circulation circuit 20 for heat-transfer fluid. The circulation circuit 20 successively includes a heat engine 21, a first pump 22 and an electric motor 100 as previously described. All of these elements are fluidly connected in series. The first pump 22 makes it possible to cause the circulation of the heat-transfer fluid in the circulation circuit 20, from the internal chamber 10 of the electric motor 100 towards the heat engine 21 so as to perform a heat exchange. The heat-transfer fluid cools the electric motor 100 when it is in operation and then transfers the stored heat energy to the heat engine 21.

[0070] In parallel and according to the arrangement illustrated in FIG. 5, the drive system 200 also comprises a refrigerant circuit 23 in which a refrigerant liquid of the electric motor 100 is intended to circulate. The refrigerant circuit 23 successively includes the electric motor 100, a second pump 24 and a heat exchanger 25 fluidly connected in series. The refrigerant liquid circulating in the internal channel 12 of the electric motor 100 may be cooled in the heat exchanger 25 thanks to the action of the second pump 24 used to cause the circulation of the refrigerant liquid. When the invention is applied to light or heavy vehicles, the heat exchanger 25 is a radiator commonly used in the field. The refrigerant liquid is cooled by the air encountered during vehicle circulation.

[0071] As represented in FIG. 5, the refrigerant circuit 23 and the circulation circuit 20 for the heat-transfer fluid are configured so that the circulation direction of the refrigerant liquid is opposite to the circulation direction of the heat-transfer fluid. FIG. 4 illustrates the heat-transfer fluid inlet 9 disposed opposite to the refrigerant fluid outlet pipe 14. Conversely, the heat-transfer fluid outlet 11 is disposed opposite to the refrigerant fluid inlet pipe 13. This configuration makes it possible to optimize the operation of the drive system 200, because it makes it possible to optimize the thermal exchange in the internal chamber 10 between the heat-transfer fluid which enters the electric motor 100 near the refrigerant liquid outlet pipe 14, i.e. where the refrigerant liquid is the warmest. Indeed, this has gained heat energy by crossing the internal channel 12, which makes the heat exchange with the heat-transfer fluid very efficient.

[0072] According to an arrangement not visible in the figures, the drive system 200 comprises a temperature sensor configured to measure the temperature of the heat-transfer fluid at the inlet of the heat engine 21. In addition, a controller provided at the first pump 22 makes it possible to communicate with the temperature sensor to pilot the operation or stopping of the first pump 22.

[0073] The controller may in particular control the starting of the first pump 22 to cause the circulation of the heat-transfer fluid in the circuit 20 and in the internal chamber 10 when the temperature of the heat-transfer fluid measured at the inlet of the heat engine is lower than a predetermined threshold temperature value, chosen so as to optimize the operation of the heat engine 21.

[0074] Conversely, the controller may control the stopping of the first pump 22 so as to stop the circulation of the heat-transfer fluid in the internal chamber 10 when the temperature of the measured heat-transfer fluid is greater than a predetermined threshold temperature value, and which would risk reversing the heat exchange with the electric motor 100. The heat-transfer fluid could indeed heat the motor 100 instead of participating in its cooling if its temperature became too high.

[0075] According to an example of application of the invention in which the drive system 200 is used for driving a motor vehicle, the controller is advantageously used to trigger the first pump 22, thanks to the results of the temperature measurements carried out by the temperature sensor. Indeed, when the vehicle is started, the heat engine 21 is cold. However, it is known that launching the heat engine 21 when cold generates many more polluting particles, including CO.sub.2. Moreover, its operation is also not optimal at low temperatures. Thus, the controller is configured so as to control the starting of the first pump 22 when the temperature of the heat-transfer fluid measured by the probe at the inlet of the heat engine 21 is below the predetermined threshold temperature, for example 90° C. The first pump 22 allows the circulation of the heat-transfer fluid (herein engine lubricating oil) in the internal chamber 10 of the electric motor 100 which heats up with the increase in the internal temperature of the active parts (rotor and stator). When the controller receives the temperature measurement and the comparison with the predetermined threshold temperature indicates that the temperature of the heat-transfer fluid is equal to or greater than approximately 90° C., the controller gives the instruction to stop the first pump 22. The heat engine 21 is then in better conditions for its start-up and then enters its standard operation, commonly used on current heat engines present on the automotive market. The electric motor 100 still operates (in the same operating modes of a traction motor) and is cooled by its own glycol circuit 23.

[0076] This exemplary application of a heat engine 21 is advantageously provided to limit the emission of CO.sub.2 from a cold engine by warming up the lubricating oil before starting it. Other examples of applications may find a benefit in optimal management of the temperature and the operation of heat engine and electric motor as well as the pollution emitted.

[0077] Thus, the present invention makes it possible to improve the cooling of an electric motor 100 in operation by a heat exchange organized in an internal chamber 10 that is easy and inexpensive to manufacture. In addition, this heat exchange may be used for heat transfer to a device that needs to be heated by creating a fluid circuit for a heat-transfer fluid between the refrigerant fluid outlet and the inlet of the device to be heated. The figures illustrate an application for heating the lubricating oil of a heat engine 21 but this system may find other applications, in particular for heating the lubricating oil of a gearbox or even for the management of the temperature (heating/cooling) of the batteries, thermal capacitors, etc . . . without departing from the scope of the invention, the invention is obviously not limited to the configuration of the invention as described above.