CARDAN FOR ELECTRIC OR HYBRID VEHICLE AND ASSOCIATED TRANSMISSION ASSEMBLY

Abstract

The present invention relates to a universal joint (3) for an electric or hybrid motor vehicle comprising an electric motor (5) for driving the universal joint (3), the universal joint (3) comprising a shaft (3a) configured to extend at the center of a rotor (5a) of the electric motor (5) in which at least one fluid deflection element (13) is provided or arranged around the shaft (3a) of the universal joint (3), said at least one deflection element (13) being configured to create a fluid displacement along the shaft (3a) of the universal joint (3) when the latter is rotated by the electric motor (5) to form a turbine and allow the rotor (5a) to be cooled. Fig.2

Description

Title of the invention: CARDAN FOR ELECTRIC OR HYBRID VEHICLE AND ASSOCIATED TRANSMISSION ASSEMBLY

[0001] The present invention is part of the field of motor vehicles and more particularly of universal joints used in electric or hybrid motor vehicles. Universal joints are used to transmit mechanical torque to the wheels of the vehicle. In the case of an electric or hybrid vehicle, this torque is provided by an electric motor. In addition, in order to optimize the space available in the vehicle, the universal joint shaft can be coaxial with the electric motor, the shaft passing through the center of the rotor of the electric motor.

[0002] However, with such a configuration, it becomes difficult to cool the rotor and the rotor guide bearings.

[0003] It is therefore necessary to find a solution for effectively cooling the rotor of an electric motor coaxial with a cardan shaft.

[0004] For this purpose, the invention relates to a universal joint for an electric or hybrid motor vehicle comprising an electric motor for driving the universal joint, the universal joint comprising a shaft configured to extend at the center of a rotor of the electric motor, characterized in that at least one fluid deflection element is provided or arranged around the shaft, said at least one deflection element being configured to create a movement of fluid along the shaft when the latter is rotated by the electric motor to form a turbine and allow the rotor to be cooled.

[0005] The use of at least one deflection element configured to cause fluid movement along the cardan shaft allows efficient cooling of the rotor and the elements arranged around the cardan shaft at reduced cost, without requiring additional devices and without additional energy consumption.

[0006] According to another aspect of the present invention, the at least one deflection element has a generally helical shape extending along the cardan shaft.

[0007] The helical shape makes it possible to obtain the turbine function and therefore the movement of the fluid along the cardan shaft during the rotation of the latter.

[0008] According to another aspect of the present invention, the gimbal comprises a plurality of deflection elements in the form of curved-shaped fins distributed around and along the shaft of the gimbal.

[0009] According to another aspect of the present invention, the at least one deflection element is provided on a tube configured to be positioned around the cardan shaft.

[0010] According to another aspect of the present invention, the tube is force-fitted around the cardan shaft.

[0011] According to another aspect of the present invention, the tube is axially locked by a retaining ring.

[0012] The present invention also relates to a transmission assembly comprising: - an electric motor comprising a stator and a rotor,

[0013] - a gimbal as described previously,

[0014] - a differential device arranged between the electric motor and the universal joint,

[0015] wherein the electric motor also comprises first and second rotor guide bearings disposed around the cardan shaft such that the fluid displacement created by the rotational drive of the cardan shaft allows the rotor and the rotor guide bearings to be cooled.

[0016] According to another aspect of the present invention, the transmission assembly also comprises a fluid circuit in which the cardan shaft is at least partially arranged, the fluid being for example oil.

[0017] According to another aspect of the present invention, the cardan shaft is in fluid communication with the outside air.

[0018] The present invention also relates to an electric or hybrid motor vehicle comprising a transmission assembly as described above.

[0019] Other characteristics and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and non-limiting example, and the appended drawings among which:

[0020] [Fig. 1] represents a schematic perspective and sectional view of a transmission assembly according to an embodiment of the present invention;

[0021] [Fig.2] represents a schematic perspective and sectional view of an electric motor and a cardan shaft coaxial with the rotor of the electric motor;

[0022] [Fig.3] represents a schematic perspective view of a tube intended to be arranged around the gimbal;

[0023] In these figures, identical elements have the same references.

[0024] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Single features of different embodiments may also be combined or interchanged to provide other embodiments.

[0025] The present invention relates to a universal joint for an electric or hybrid motor vehicle.

[0026] [Fig.l] represents a transmission assembly 1 comprising a universal joint 3 and an electric motor 5 configured to drive a shaft 3a of the universal joint 3 in rotation. Electric motor 5 comprises a stator 5b and a rotor 5a extending in the center of the stator 5b. The rotor 5a is guided in rotation by two guide bearings 11a and 11b. The cardan shaft 3a is configured to extend coaxially with the rotor 5a of the electric motor 5. The cardan shaft 3a of the cardan 3 extends at least partially in the center of the rotor 5a of the electric motor 5. The transmission assembly 1 may also comprise a reduction gear 7 which may be connected to the output of the electric motor 5. The transmission assembly 1 may also comprise a differential device 9 which may be connected to the output of the reduction gear 7. Thus, the input of the reduction gear 7 may be connected to the output shaft of the electric motor 5 and the output of the reduction gear 7 may be connected to the input of the differential 9, the output of the differential 9 being connected to the shaft 3a of the cardan 3. The electric motor 5 therefore drives the shaft 3a of the cardan 3 in rotation via the reduction gear 7 and the differential 9.The shaft 3a of the cardan shaft 3 is configured to drive a wheel of the motor vehicle. The differential 9 can be connected to a first cardan shaft associated with a first wheel of the vehicle and a second cardan shaft associated with a second wheel of the vehicle.

[0027] In addition, the cardan shaft 3a comprises at least one deflection element 13 for a fluid better visible in FIGS. 2 and 3. The deflection element(s) 13 are configured to form a turbine, i.e. to move a fluid along the cardan shaft 3a of the cardan 3 during rotation of the cardan shaft 3a of the cardan 3. This fluid is for example air, in this case, the cardan shaft 3a of the cardan 3 may be in fluid communication with the air outside the motor vehicle. A conduit extending for example from the front face of the vehicle to the cardan shaft 3a of the cardan 3 is for example provided on the vehicle. Alternatively, the fluid may be a liquid or oil.In this case, the cardan shaft may be arranged at least partially within a fluid circuit comprising a reservoir of liquid or oil, the cardan shaft acting as a turbine so that the fluid circuit does not require a pumping device to circulate the liquid or oil in the fluid circuit.

[0028] In the present embodiment, the cardan shaft 3a comprises a plurality of deflection elements 13 made of fins. The fins 13 have, for example, a curved shape and are distributed regularly around and along the cardan shaft 3a 3. The fins 13 may be arranged in the form of rows parallel to the axis of the cardan shaft 3a 3. The fins 13 are, for example, arranged in a helical pattern or in different helical patterns. Alternatively, the cardan shaft 3a 3 may comprise a single deflection element 13, for example a spiral-shaped element extending along the cardan shaft 3a 3.

[0029] According to an embodiment shown in Figures 2 and 3, the deflection elements 13, here the fins, are arranged on a tube 15 configured to come and position around the shaft 3a of the universal joint 3. The tube can be force-fitted onto the universal joint shaft. In addition or as an alternative, one or two retaining rings 17 can be used to block the axial movement of the tube 15 relative to the universal joint shaft 3a 3. The retaining ring 17 is for example a circlip configured to be positioned in a peripheral groove formed in the universal joint shaft 3a 3. Alternatively, the retaining ring 17 can be tightened around the universal joint shaft 3a 3. A retaining ring 17 can be arranged at each end of the tube 15. In the example of [Fig.l], the tube 15 bears against an element of the differential 9 at a first end and is axially blocked by a retaining ring 17 at a second end.

[0030] According to another embodiment, the deflection element(s) 13 may be provided directly on the shaft 3a of the cardan shaft 3. The deflection elements 13 come, for example, from the same material as the shaft 3a of the cardan shaft 3. The shaft 3a of the cardan shaft 3 is, for example, obtained by machining.

[0031] Thus, in operation, the electric motor 5 drives the cardan shaft 3a in rotation via the reducer 7 and the differential 9. The rotation of the cardan shaft 3a then causes, due to the presence of the deflection elements 13, the movement of the fluid along the cardan shaft 3a 3. The fluid is for example air coming from outside the vehicle or oil circulating in a fluid circuit, a portion of which passes through the center of the rotor 5a. This circulation of fluid makes it possible to cool the rotor 5a as well as the guide bearings 11a, 11b of the rotor 5a.

[0032] The use of a cardan shaft 3a coaxial with the rotor 5a and comprising deflection elements 13 making it possible to circulate a cooling fluid in the center of the rotor therefore makes it possible to effectively cool the rotor 5a and the guide bearings 11a, 11b of the latter without requiring additional devices and without additional energy consumption.

Claims

Claims

1. Cardan (3) for an electric or hybrid motor vehicle comprising an electric motor (5) for driving the cardan (3), the cardan (3) comprising a shaft (3a) configured to extend at the center of a rotor (5a) of the electric motor (5) characterized in that at least one fluid deflection element (13) is provided or arranged around the shaft (3a) of the cardan (3), said at least one deflection element (13) being configured to create a movement of fluid along the shaft (3a) of the cardan (3) when the latter is rotated by the electric motor (5) to form a turbine and allow the rotor (5a) to be cooled.

2. Cardan (3) according to the preceding claim in which the at least one deflection element (13) has a generally helical shape extending along the shaft (3a) of the cardan (3).

3. Cardan (3) according to one of the preceding claims comprising a plurality of deflection elements (13) in the form of fins of curved shape and distributed around and along the shaft (3a) of the cardan (3).

4. Cardan (3) according to one of the preceding claims in which the at least one deflection element (13) is provided on a tube (15) configured to be positioned around the shaft (3a) of the cardan (3).

5. Cardan (3) according to the preceding claim in which the tube (15) is force-mounted around the shaft (3a) of the cardan (3).

6. Cardan (3) according to one of claims 4 or 5 in which the tube (15) is axially blocked by a retaining ring (17).

7. Transmission assembly (1) comprising: - an electric motor (5) comprising a stator (5b) and a rotor (5a), - a universal joint (3) according to one of the preceding claims, - a differential device (9) arranged between the electric motor (5) and the universal joint (3), in which the electric motor (5) also comprises a first (11a) and a second (11b) guide bearing of the rotor (5a) arranged around the shaft (3a) of the universal joint (3) so that the fluid displacement created by the rotational drive of the shaft (3a) of the universal joint (3) makes it possible to cool the rotor (5a) and the guide bearings (11a, 11b) of the rotor (5a).

8. Transmission assembly (1) according to the preceding claim also comprising a fluid circuit in which is arranged at less partially the shaft (3a) of the cardan shaft (3), the fluid is for example oil.

9. Transmission assembly (1) according to one of claims 1 to 7 in which the cardan shaft (3a) is in fluid communication with the outside air.

10. Electric or hybrid motor vehicle comprising a transmission assembly (1) according to one of claims 7 to 9.

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