Cooling system for electric motor.

Abstract

Cooling system for an electric motor of a motor vehicle. Cooling system (5) for an electric motor (2) comprising a stator (23) and a shaft (22) having a first axis of rotation (221), the motor being intended to be housed in a gearbox (10) casing (1), characterized in that the system (5) comprises a first circuit (55) including at least one conduit (54) adapted to create a circulation (53) of oil collected in a lower part (101) of the casing (10), then channeled to the electric motor (2) to provide initial cooling of the electric motor (2). Figure for the abstract: 1

Description

Title of the invention: Cooling system for electric motor.

[0001] The invention relates to a cooling system for an electric motor.

[0002] So-called secondary electric motors can be installed in thermal motor vehicles, for example to improve the comfort of use of the gearbox.

[0003] The installation of a secondary electric motor requires the integration of a cooling system for the secondary electric motor into the vehicle. However, the solutions currently implemented for cooling a secondary electric motor have drawbacks.

[0004] The aim of the invention is to provide a solution that overcomes the above drawbacks. In particular, the invention makes it possible to produce a cooling system for an electric motor that is simple and reliable and that reduces the size, the cost of parts and the assembly time of a cooling system for an electric motor.

[0005] For this purpose, the invention relates to a cooling system for an electric motor comprising a stator and a shaft having a first axis of rotation, the motor being intended to be arranged in a gearbox housing. The system comprises a first circuit comprising at least one conduit capable of creating a circulation of an oil collected in a lower part of the housing, then channeled towards the electric motor to implement a first cooling of the electric motor.

[0006] In one embodiment, the cooling system comprises means for implementing a second cooling of the electric motor by spraying an oil contained in the casing, the spray being created by rotation of at least a first pinion of the gearbox.

[0007] In one embodiment, the first circuit comprises: - a means for cooling an oil circulating in the at least one conduit, and / or - a means for controlling the pressure of an oil circulating in the at least one conduit.

[0008] In one embodiment, the cooling system comprises a first support intended to be fixed to the casing, and the first circuit comprises means for conveying oil to an interior surface of the first support intended to contain the stator of the electric motor.

[0009] In one embodiment, the conveying means comprise at least a first channel extending mainly in a direction substantially parallel to the first axis of rotation, the at least one first channel is hollowed out in a thickness of an upper part of the first support, between an inlet of the at least one first channel and an outlet of the at least one first channel produced on an internal face of the first support, the internal face of the first support being intended to be in contact with the stator of the electric motor.

[0010] In one embodiment, the conveying means further comprises a second channel such that a second height of the second channel is less than a first height of the first channel, the first and second heights being measured vertically relative to the first axis of rotation, and / or a second length of the second channel is less than a first length of the first channel, the first and second lengths being measured along the direction of the first axis of rotation.

[0011] The invention further relates to a cooling system according to the invention comprising an oil reservoir arranged upstream of the at least one channel of the first circuit for its supply with oil.

[0012] In one embodiment, the oil reservoir comprises - a first opening for the passage of oil from the reservoir to a pinion of the electric motor shaft and / or to a ball bearing of the electric motor shaft, for their lubrication, and / or - a second opening for the passage of oil from the reservoir to a bun of the stator of the electric motor, for its cooling, and / or - a third opening for the passage of oil from the reservoir towards a groove made on a lateral face of the first support, the groove extending to guide oil towards a housing for bearings of an intermediate shaft of the gearbox.

[0013] In one embodiment, the first support comprises a fourth opening in its lower portion, the fourth opening allowing gravity flow out of the first support of oil heated by the electric motor.

[0014] The invention further relates to a gearbox comprising a housing, an electric motor disposed in the housing, and a cooling system for the electric motor according to the invention.

[0015] The invention also relates to a powertrain comprising a gearbox according to the invention and a heat engine driving the gearbox.

[0016] The invention further relates to a motor vehicle comprising a powertrain according to the invention or a gearbox according to the invention or a cooling system according to the invention.

[0017] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of a particular embodiment made without limitation in relation to the attached figures among which:

[0018] [Fig.l] schematically represents a motor vehicle equipped with a cooling system according to one embodiment of the invention.

[0019] [Fig.2] is a first longitudinal section of a cooling system according to the invention.

[0020] [Fig.3] is a first cross-section of a cooling system according to the invention.

[0021] [Fig.4] is a second cross-section of a cooling system according to the invention.

[0022] [Fig.5] is a first perspective view of a cooling system according to the invention.

[0023] [Fig.6] is a second longitudinal section of a cooling system according to the invention.

[0024] [Fig.7] is a second perspective view of a cooling system according to the invention.

[0025] An embodiment of a motor vehicle 100 according to the invention is described below with reference to [Fig. 1]. The motor vehicle 100 is a motor vehicle of any type, in particular a passenger vehicle or a utility vehicle.

[0026] The motor vehicle 100 is equipped with a powertrain 6 comprising a gearbox 1 and a heat engine 3 driving the gearbox 1. The gearbox 1 comprises a housing 10, an electric motor 2 arranged in the housing 10, and a system 5 for cooling the electric motor. The gearbox 1 is part of a powertrain 6 of the motor vehicle 100.

[0027] In the embodiment described, the electric motor 2 is a so-called secondary motor which facilitates the synchronization of the gears of the gearbox 1 during a gear change. In other embodiments, the electric motor 2 could be intended for another use, for example starting the thermal engine or the alternator function. The gearbox 1 and the electric motor 2 are arranged in the same casing 10, in particular in a casing usually intended for the gearbox.

[0028] The mounting of the electric motor 2 in the casing 10 of the gearbox 1 is carried out by means of a first support 51. The first support 51 is part of a system 5 for cooling the electric motor 2. The first support 51 is a part of a housing surrounding the electric motor 2. It is fixed in an upper part of the casing 10 of the gearbox 1.

[0029] [Fig.l] represents a section of the engine 2 along a vertical plane passing through a first axis of rotation 221 of a shaft 22 of the electric motor 2. A rotational movement of the shaft 22 around the first axis is generated by a rotational movement of a rotor 24 mounted integrally with the shaft 22. The rotational movement of the rotor around the first axis 221 is itself generated by an electromagnetic field created by an electric current flowing in the rotor 24. In other words, an electric current passing through windings of the rotor 24 causes an electromagnetic field which reacts with the electromagnetic field of the stator 23, which creates a rotational movement of the assembly constituted by the shaft 22 and the rotor 24.

[0030] The stator 23 is fixed relative to the first support 51. In one embodiment, the stator 23 is fitted with a clamping fit in a cylindrical bore made in the first support 51. Thus, an outer surface 231 of the stator 23 bears on an inner surface 513 (or inner face 513) of the first support 51. In an advantageous embodiment of the invention described later in the document, for cooling the engine 2, an oil circulation is created at the inner surface 513 (or inner face 513) of the first support 51. More particularly, an upper part of said interface is targeted, i.e. the upper part 511 of the first support 51 is modified so as to create an oil circulation which can then flow by gravity over a larger surface of said interface.

[0031] The first support 51 further comprises a first housing 516 for a ball bearing allowing rotational guidance of a first end 222 of the shaft 22. The first support is advantageously equipped with a cover 57 having a second housing 571 for a ball bearing allowing rotational guidance of a second end 223 of the shaft 22.

[0032] A first pinion 25 of the electric motor 2 is mounted integral with the shaft 22. It is intended to mesh with a second pinion 11 of the gearbox 1 as is more specifically visible in [Fig.l].

[0033] In addition, the first support 51 comprises a third housing 517 intended to receive a ball bearing for guiding the second pinion 11.

[0034] Thus, the first support 51 and the cover 57 together form a housing surrounding the electric motor 2, in particular a housing surrounding a portion of the shaft 22, the stator 23 and the rotor 24.

[0035] The motor vehicle further comprises a system 5 for cooling the electric motor 2. The system 5 comprises a first circuit 55 containing at least one conduit 54 capable of creating a circulation 53 of an oil collected in a lower part 101 of the casing 10, then channeled towards the electric motor 2 to implement a first cooling of the electric motor 2.

[0036] In addition to the first cooling generated by the first circuit 55, the system 5 comprises means for implementing a second cooling of the engine. electric 2 carried out by projection of an oil contained in the casing 10, the projection being created by rotation of at least a first pinion 11 of the gearbox 1.

[0037] Thus the electric motor 2 arranged in the casing 10 can benefit from two sources of cooling, including the second cooling which is naturally generated by a projection of oil onto an external wall of the first support 51.

[0038] In order to implement the first cooling, the circuit 55 contains at least one conduit 54 making it possible to take oil from a lower part 101 of the casing 10 (forming a supply tank) and to convey this oil to the engine 2. In one embodiment, the oil is reinjected inside the first support 51 via a conduit 102 for supplying oil to the casing 10, the conduit 102 interfacing with a connection surface 518 of the first support 51.

[0039] In an embodiment more specifically detailed by [Fig.2], the interface between the conduit 102 and the connection surface 518 delimits a volume forming a reservoir 56 for the oil conveyed by the circuit 55. The reservoir 56 makes it possible to guarantee continuity of cooling and lubrication of the electric motor 2 even when a high rotation speed of the shaft 22 creates a suction of oil into the casing 10. In other words, the reservoir 56 makes it possible to compensate for an underpressure at the inlet of the oil inlet in the casing 10. Other advantages of the reservoir 56 will be detailed later in this document.

[0040] The first circuit 55 can advantageously comprise - a means 541 for cooling an oil circulating in the at least one conduit 31, and / or - a means for controlling a pressure 542 of an oil circulating in the at least one conduit 31.

[0041] Indeed, the oil taken from a lower part of the casing may be too hot to cool the electric motor 2. The cooling means 541 can thus bring the oil circulating in the at least one conduit 54 to a temperature allowing the cooling of the motor 2.

[0042] The pressure control means 542 further allows the movement of an oil circulating in the at least one conduit 54 between a sampling point located in a lower part 101 of the casing 10 and a point of injection of the oil into the support 51 located in an upper part of the casing. In one embodiment, the pressure control means 542 may be a pump. The pressure control means 542 may further comprise a nozzle 5421, more specifically visible in [Fig. 2], making it possible to regulate the flow of oil in the first circuit 55.

[0043] In a preferred embodiment, the first circuit 55 comprises means 52 for conveying the oil to an inner surface 513 of the first support 51, the inner surface being intended to contain the stator 23 of the electric motor 2.

[0044] For this purpose, the conveying means 52 may comprise at least one first channel 521, 522, 523, 524, 525, 526, 527, 528, 529 extending mainly in a direction substantially parallel to the first axis of rotation 221, the at least one first channel being hollowed out in a thickness 512 of an upper part 511 of the first support 51, between an inlet of the at least one first channel 521, 522, 523, 524, 525, 526, 527, 528, 529 and an outlet of the at least one first channel 521, 522, 523, 524, 525, 526, 527, 528, 529, the output being produced on an internal face 513 of the first support 51, and the internal face 513 of the first support 51 being intended to be in contact with the stator 23 of the electric motor 2.

[0045] An embodiment of a circuit 5 comprising nine channels 521 to 529 is illustrated by Figures 2 to 5.

[0046] [Fig. 2] represents a longitudinal sectional view of the electric motor 2 arranged in the first support 51, the sectional plane being a vertical plane containing the first axis of rotation 221. Thus, the channel 525 located in the sectional plane appears clearly on the upper part of the first support 51.

[0047] [Fig. 3] is a detailed view of the channels 521 to 529 along a first transverse section plane BB, perpendicular to the first axis of rotation 221.

[0048] [Fig. 4] is a detailed view of the channels 521 to 529 along a second transverse section plane DD, perpendicular to the first axis of rotation 221, the section plane DD being further from the oil reservoir 56 than the section plane BB.

[0049] [Fig. 5] is a perspective view of the electric motor 2 illustrating an embodiment of the channels 521 to 529, in which the length of the channels 521 to 529 varies as a function of their position, in particular their height relative to the first axis of rotation 221, that is to say as a function of a height of the channel measured relative to a horizontal plane passing through the first axis of rotation 221.

[0050] [Fig. 5] illustrates the fact that the channels 521 to 529 extend mainly in a direction substantially parallel to the first axis of rotation 221. Figures 3 and 4 illustrate the fact that the channels 521 to 529 are hollowed out in the thickness 512 of the upper part 511 of the first support 51.

[0051] The section plane BB, corresponding to [Fig. 3], represents a section of the first support 51 which is close to the oil inlet in the engine 2, in particular close to the reservoir 56. As can be seen in [Fig. 3], at a close distance from the oil inlet, the nine channels 521 to 529 are still closed. In other words, the runoff of the oil at the interface between the first support 51 and the stator 23 is not implemented on the portion of the engine located between the reservoir 56 and the section plane BB cut.

[0052] The section plane DD, corresponding to [Fig. 4], represents a section of the first support 51 which is distant from the oil inlet in the engine 2. As can be seen in [Fig. 4], at a distance distant from the oil inlet, the most lateral channels, in particular the channels 521, 522, 523, 527, 528, 529, open out at the level of the internal face 513 of the first support 21, which is in contact with the stator 23. The oil circulating in the most lateral channels then flows onto the stator 23, for its cooling.

[0053] [Fig. 5] provides an overview of an oil runoff on the stator created by the channels 521 to 529. With reference to [Fig. 5], the relative lengths L1, L2 of the channels 526 and 529 can be compared as a function of their respective heights H1, H2. The height H1 of the channel 526 being greater than the height H2 of the channel 529, the length L1 of the channel 526 will be greater than the height H2 of the channel 529

[0054] More generally, in the embodiment of the channels described by FIGS. 2 to 5, the channels are arranged so that if we consider a first and a second channel, such that a second height H2 of the second channel is less than a first height H1 of the first channel, the first and second heights H1, H2 being measured vertically relative to the first axis of rotation 221, then a second length L2 of the second channel is less than a first length L1 of the first channel, the first and second lengths L1, L2 being measured in the direction of the first axis of rotation 221.

[0055] To ensure the efficiency of the flow of the gearbox oil onto the stator, it is necessary to size the section and the quantity of the grooves according to the available flow rates of cooled oil from the gearbox. In addition, the channels are preferably arranged and distributed angularly in the upper part of the first support 51. For example, the channels can be distributed over an angular amplitude of 45 degrees on either side of an upper edge of the stator. In addition, the channels are advantageously of different lengths to promote axial distribution of the oil flow.

[0056] In one embodiment illustrated by Figures 2 and 7, the reservoir 56 may comprise - a first opening 561 for the passage of oil from the reservoir 56 to a pinion 25 of the shaft 22 of the electric motor 2 and / or to a ball bearing 26 of the shaft 22 of the electric motor 2, for their lubrication, and / or, - a second opening 562 for the passage of oil from the reservoir 56 to a bun 25 of the stator 23 of the electric motor 2, for its cooling, - a third opening 563 for the passage of oil from the reservoir 56 towards a groove 5191 made on a lateral face 519 of the first support 51, and the groove 5191 extends to guide oil to a housing 517 for bearings 13 of an intermediate shaft 12 of the gearbox 1.

[0057] Furthermore, in an embodiment shown in [Fig. 6], the first support 51 may comprise a fourth opening 514 in its lower part 515, the fourth opening 514 allowing a flow by gravity out of the first support 51 of an oil heated by the electric motor 2. The oil is then collected in the casing 10 of the gearbox 1.

[0058] The invention further relates to a gearbox 1 comprising a casing 10, an electric motor 2 arranged in the casing 10, and a system 5 for cooling the electric motor according to the invention.

[0059] The invention also relates to a powertrain 6 comprising such a gearbox 1 and / or a system 5 for cooling an electric motor according to the invention.

[0060] The invention also relates to a motor vehicle 100 comprising such a powertrain 6, and / or a gearbox 1 according to the invention and / or a system 5 for cooling an electric motor according to the invention.

[0061] Finally, the cooling system according to the invention makes it possible to improve the efficiency of the cooling of an electric motor by creating a circulation of cooled oil as close as possible to the hot parts of the electric motor, in particular at the level of a stator of the electric motor.

[0062] Simultaneously with this first internal cooling, the cooling system according to the invention allows a second external cooling, by spraying an oil contained in the gearbox casing onto the first support 51 forming with the cover 57 a housing or casing for the electric motor 2.

[0063] In addition, the first support 51 offers the possibility of integrating other cooling or lubrication functions for components of the electric motor or the gearbox into the cooling system according to the invention. In particular, the cooling system according to the invention makes it possible to lubricate a pinion and a bearing of the shaft of the electric motor, as well as bearings of an intermediate shaft of the gearbox. The cooling system according to the invention also makes it possible to convey oil directly to a bun of the stator, for its cooling.

[0064] Advantageously, the creation of an atmospheric pressure oil reservoir at the inlet of the first support 51 makes it possible to ensure the continuity of the lubrication of the electric motor. The cooling system according to the invention makes it possible to consume the oil flow as best as possible without having significant pressure losses in the oil distribution circuit.

[0065] These various improvements are also implemented without altering the lubrication of the gearbox pinions.

[0066] Thanks to the cooling system according to the invention, the temperatures of the electric motor and the gearbox are better controlled. The invention thus allows the integration of the electric motor in the gearbox housing. Indeed, without double cooling of the electric motor as implemented by the invention, the temperature reached by the rotor of the electric motor could exceed an admissible limit and damage the electric motor.

[0067] The integration of the electric motor in the gearbox casing has multiple advantages. It makes it possible, on the one hand, to reduce the size of the stator cooling system and, on the other hand, to take advantage of the supports (in particular the first support 51) to create suitable arrangements conveying the oil as close as possible to hot zones of the electric motor or the gearbox.

[0068] In addition, the cooling system according to the invention makes it possible to reduce the cost of the parts necessary for implementing the distribution of oil in the electric motor and in the gearbox.

[0069] Furthermore, the assembly time of a cooling system according to the invention is reduced compared to an assembly time which would be necessary if two independent cooling systems were implemented for the gearbox on the one hand and the electric motor on the other.

Claims

Claims

1. System (5) for cooling an electric motor (2) comprising a stator (23) and a shaft (22) having a first axis of rotation (221), the motor being intended to be arranged in a casing (10) of a gearbox (1), characterized in that the system (5) comprises a first circuit (55) comprising at least one conduit (54) capable of creating a circulation (53) of an oil collected in a lower part (101) of the casing (10), then channeled towards the electric motor (2) to implement a first cooling of the electric motor (2).

2. Cooling system (5) according to the preceding claim, characterized in that it comprises means for implementing a second cooling of the electric motor (2) by projection of an oil contained in the casing (10), the projection being created by rotation of at least a first pinion (11) of the gearbox (1).

3. Cooling system (5) according to one of the preceding claims, characterized in that the first circuit (55) comprises - a means (541) for cooling an oil circulating in the at least one conduit (54), and / or - a means (542) for controlling a pressure of an oil circulating in the at least one conduit (54).

4. Cooling system (5) according to one of the preceding claims, characterized in that it comprises a first support (51) intended to be fixed to the casing (10) and in that the first circuit (55) comprises means (52) for conveying the oil to an inner surface (513) of the first support (51) intended to contain the stator (23) of the electric motor (2).

5. Cooling system (5) according to the preceding claim, characterized in that the conveying means (52) comprise at least one first channel (521, 522, 523, 524, 525, 526, 527, 528, 529) extending mainly in a direction substantially parallel to the first axis of rotation (221), in that the at least one first channel (521, 522, 523, 524, 525, 526, 527, 528, 529) is hollowed out in a thickness (512) of an upper part (511) of the first support (51), between an inlet of the at least one first channel (521, 522, 523, 524, 525, 526, 527, 528, 529) and an outlet of the at least one first channel (521, 522, 523, 524, 525, 526, 527, 528, 529) produced on an internal face (513) of the first support (51), the internal face (513) of the first support (51) being intended to be in contact with the stator (23) of the electric motor (2).

6. Cooling system (5) according to the preceding claim, characterized in that the conveying means (52) further comprise a second channel (521, 522, 523, 524, 525, 526, 527, 528, 529) such that a second height (H2) of the second channel (521, 522, 523, 524, 525, 526, 527, 528, 529) is less than a first height (Hl) of the first channel (521, 522, 523, 524, 525, 526, 527, 528, 529), the first and second heights (Hl, H2) being measured vertically relative to the first axis of rotation (221), and / or in that a second length (L2) of the second channel (521, 522, 523, 524, 525, 526, 527, 528, 529) is less than a first length (Ll) of the first channel (521, 522, 523, 524, 525, 526, 527, 528, 529), the first and second lengths (Ll, L2) being measured in the direction of the first axis of rotation (221).

7. Cooling system (5) according to claim 5 or 6, characterized in that it comprises an oil reservoir (56) arranged upstream of the at least one channel (521, 522, 523, 524, 525, 526, 527, 528, 529) of the first circuit (55) for its oil supply.

8. Cooling system (5) according to the preceding claim, characterized in that the oil reservoir (56) comprises - a first opening (561) for the passage of oil from the reservoir (56) to a pinion (25) of the shaft (22) of the electric motor (2) and / or to a ball bearing (26) of the shaft (22) of the electric motor (2), for their lubrication, and / or - a second opening (562) for the passage of oil from the reservoir (56) to a bun (25) of the stator (23) of the electric motor (2), for its cooling, and / or - a third opening (563) for the passage of oil from the reservoir (56) to a groove (5191) made on a lateral face (519) of the first support (51), and in that the groove (5191) extends to guide oil to a housing (517) for bearings (13) of an intermediate shaft (12) of the gearbox (1).

9. Cooling system (5) according to one of the preceding claims, characterized in that the first support (51) comprises a fourth opening (514) in its lower part (515), the fourth opening (514) allowing a flow by gravity out of the first support (51) of an oil heated by the electric motor (2).

10. Gearbox (1) comprising a housing (10), an electric motor (2) arranged in the housing (10), and a system (5) for cooling the electric motor according to one of the preceding claims.

11. Powertrain (6) comprising a gearbox (1) according to the preceding claim and a heat engine (3) driving the gearbox (1).

12. Motor vehicle (100) comprising a powertrain (6) according to the preceding claim or a gearbox according to claim 10 or a cooling system (5) according to one of claims 1 to 9.

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