Flow path assembly, drivetrain system and vehicle

Abstract

The present disclosure relates to a flow path assembly for a drivetrain system, the flow path assembly comprising an electric motor shaft that can rotate around a rotation axis and comprises a first end and a second end that is opposite the first end; and a transmission shaft, which is in transmission connection with the electric motor shaft and coaxially arranged therewith. The electric motor shaft comprises a first central hole that forms a part of a flow path, and first and second cooling holes that communicate with this first central hole. The first cooling hole is near the first end, and the second cooling hole is near the second end. A separating part is further provided in the first central hole of the electric motor shaft, and separates the first central hole into a first section that communicates with the first cooling hole and a second section that communicates with the second cooling hole. The transmission shaft comprises a second central hole that forms a part of the flow path, and first and second communicating holes, the first communicating hole connecting the second central hole with the first section, and the second communicating hole connecting the second central hole with the second section. The present disclosure further relates to a drivetrain system comprising the flow path assembly, and a vehicle comprising the drivetrain system.

Description

[0001] Flow path assembly, drivetrain system and vehicle

[0002] Technical Field

[0003] The present disclosure relates to a flow path assembly for a drivetrain system. The present disclosure further relates to a drivetrain system comprising such a flow path assembly, and a vehicle comprising such a drivetrain system.

[0004] Background

[0005] A drivetrain system of a vehicle comprises an electric motor for driving the vehicle and a transmission component, such as a gearbox. The electric motor shaft of the electric motor and the transmission shaft of the gearbox are rotationally coupled to transmit torque from the electric motor to the gearbox. In view of compactness and transmission efficiency, the electric motor and gearbox of the drivetrain system may be integrated together.

[0006] The electric motors used to drive vehicles usually have greater power and generate a large amount of heat when running continuously. If heat dissipation is insufficient, the heat generated will accumulate inside the electric motor, causing the temperature of the electric motor to rise and affecting the reliability and performance of the electric motor. Oil-cooled electric motors can bring a cooling medium (cooling oil) into direct contact with the internal components of the electric motor, and so have a better cooling effect and are used increasingly extensively in the field of vehicles. Cooling oil is usually introduced to an oil- cooled electric motor through an electric motor shaft located at the axis centre of the electric motor, and a centrifugal force generated when the electric motor rotates causes the cooling oil to be sprayed radially outward to cool various components of the electric motor.

[0007] The windings of the stator are a major heat-generating component of the electric motor and generally include ends extending beyond the stator main body at both axial ends of the electric motor. Therefore, it is desired that the cooling oil entering the electric motor can be sprayed directly to the windings of the stator at both axial ends of the electric motor to cool the windings. In an oil path of an i integrated drivetrain system, the electric motor is generally downstream of the gearbox; the cooling oil flows from the transmission shaft of the gearbox into the electric motor shaft of the electric motor, and is then sprayed radially outward at both axial ends. This type of oil path readily causes the cooling oil to be distributed unevenly at the two axial ends; that is, more cooling oil is sprayed to the axial end of the electric motor near the gearbox, and less cooling oil is sprayed to the axial end of the electric motor remote from the gearbox. However, the amount of heat emitted by the stator windings at the two axial ends of the electric motor is about the same. Such an uneven distribution of cooling oil necessitates increasing the flow of the cooling oil, to satisfy requirements at the axial end of the electric motor remote from the gearbox, resulting in a rise in costs.

[0008] Therefore, a flow path assembly for a drivetrain system is required, wherein a cooling fluid, such as cooling oil, can be evenly distributed to both axial ends of the electric motor, so as to fully cool the different parts of the electric motor.

[0009] Summary of the Invention

[0010] In view of the problem and requirement mentioned above, the present disclosure proposes a new type of flow path assembly for a drivetrain system; the flow path assembly solves the above problem and brings about other technical effects by adopting the following technical features.

[0011] The flow path assembly for a drivetrain system according to the present disclosure comprises: an electric motor shaft that can rotate around a rotation axis and comprises a first end and a second end that is opposite the first end; and a transmission shaft, which is in transmission connection with the electric motor shaft and coaxially arranged therewith. The electric motor shaft comprises a first central hole that forms a part of a flow path, and a first cooling hole and a second cooling hole that communicate with the first central hole, the first cooling hole being near the first end, and the second cooling hole being near the second end. A separating part is further provided in the first central hole of the electric motor shaft, and separates the first central hole into a first section that communicates with the first cooling hole and a second section that communicates with the second cooling hole. The transmission shaft comprises a second central hole that forms a part of the oil path, and a first communicating hole and a second communicating hole, the first communicating hole connecting the second central hole with the first section, and the second communicating hole connecting the second central hole with the second section.

[0012] One of the objectives of the present disclosure is to provide a flow path assembly for a drivetrain system, wherein a cooling fluid, such as cooling oil, can be evenly distributed to both axial ends of the electric motor, so as to fully cool the different parts of the electric motor. The first central hole of the electric motor shaft of the flow path assembly according to the present disclosure is separated into a first section and a second section by means of the separating part, the second central hole of the transmission shaft respectively communicating with the first section and the second section by means of the first and second communicating holes. Thus, the cooling fluid can flow from the second central hole of the transmission shaft, through the first and second communicating holes, respectively, into the first section and section of the first central hole of the electric motor shaft, and then spray toward both axial ends of the stator winding, through the first cooling hole and the second cooling hole, respectively, under the action of centrifugal force. Under the effect of the separating part, the cooling fluid that flows into one of the first section and the second section does not flow into the other. Therefore, the proportion of cooling fluid sprayed onto the two axial ends of the stator winding can be precisely controlled; that is, an even distribution of cooling fluid can be realized, and cooling fluid can also be distributed unevenly in a specific proportion when required.

[0013] The drivetrain system according to the present disclosure may further have one or more of the following features individually or in combination.

[0014] According to an embodiment of the present disclosure, the transmission shaft is inserted into the first central hole of the electric motor shaft and extends past the separating part. That is, the separating part does not completely obstruct the first central hole, but has a central hole through which the transmission shaft can pass. A flow path assembly with such a construction facilitates the electric motor shaft and transmission shaft to be fitted together, and facilitates the second central hole of the transmission shaft to communicate with the first and second sections by means of the first and second communicating holes.

[0015] According to an embodiment of the present disclosure, a certain radial gap is provided between the separating part and the transmission shaft. Thus, the transmission shaft can conveniently extend past the separating part.

[0016] According to an embodiment of the present disclosure, the first communicating hole and the second communicating hole are radial holes with axial positions located on two sides of the separating part. Thus, the first communicating hole and the second communicating hole can respectively communicate with the first section and the second section of the first central hole. Optionally, the first communicating hole and the second communicating hole are arranged near the separating part on two sides of the separating part.

[0017] According to an embodiment of the present disclosure, the first communicating hole and / or the second communicating hole is a slanted hole that forms a certain angle with a radial direction.

[0018] According to an embodiment of the present disclosure, the first communicating hole and the second communicating hole communicate with the second central hole at the same axial position. Thus, the cooling fluid flows from the second central hole, at the same axial position, to the first communicating hole and the second communicating hole. This can ensure that the cooling fluid flowing into the first communicating hole and the second communicating hole has the same fluid pressure, ensuring an even distribution of cooling fluid.

[0019] According to an embodiment of the present disclosure, the first communicating hole and the second communicating hole communicate with the second central hole at the axial position of the separating part. In view of the slanted construction of the first communicating hole and the second communicating hole, the first communicating hole and the second communicating hole can respectively lead into the first section and the second section of the second central hole.

[0020] According to an embodiment of the present disclosure, the first communicating hole and the second communicating hole communicate with one end of the second central hole. Thus, the length by which the transmission shaft is inserted into the first central hole that is required for the first and second communicating holes to respectively communicate with the first and second sections is reduced to the greatest extent possible, reducing the difficulty of assembling the electric motor shaft and the transmission shaft.

[0021] According to an embodiment of the present disclosure, the diameter of the first communicating hole is the same as the diameter of the second communicating hole, or the diameter of the first communicating hole is different to the diameter of the second communicating hole.

[0022] According to an embodiment of the present disclosure, the separating part is arranged to be near the first end or the second end of the electric motor shaft.

[0023] According to an embodiment of the present disclosure, the separating part is an annular separating rib that extends from an inner wall of the first central hole of the electric motor shaft towards the centre.

[0024] The present disclosure further relates to a drivetrain system comprising the flow path assembly as described above.

[0025] The present disclosure further relates to a vehicle comprising the drivetrain system as described above.

[0026] Brief Description of the Drawings

[0027] The foregoing and other features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings, and the description and the accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. The drawings below have not been drawn by meticulously reducing or enlarging actual dimensions in equal proportion, but focus on showing the substance of the present disclosure.

[0028] Fig. 1 shows a partial sectional view of a drivetrain system according to the present disclosure.

[0029] Fig. 2 schematically shows a sectional view of a flow path assembly according to the present disclosure.

[0030] Detailed Description of Embodiments

[0031] To clarify the objective, technical solutions and advantages of embodiments of the present disclosure, the technical solutions of the embodiments of the present disclosure are described clearly and completely below in conjunction with the drawings of the embodiments of the present disclosure.

[0032] Unless defined otherwise, the technical or scientific terms used herein shall have the common meanings as understood by those of ordinary skill in the field to which the present disclosure belongs. Words such as "one", "a" or "the" used in the description and the claims of the patent application disclosed herein do not indicate a quantity limit, but mean that there is at least one. Words such as “comprise” or "include” mean that the element or object appearing before the term covers the elements or objects and equivalents thereof listed after the term. Words such as "connect" or "link" are not restricted to a physical or mechanical connection, and may include an electrical connection, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like are only used to indicate the relative positional relationship, and when the absolute position of a described object changes, the relative positional relationship may also change accordingly. The terms “axial" and “axial direction” refer to the direction of the rotation axis X of the electric motor, and the terms “radial” and “radial direction” refer to directions perpendicular to the rotation axis X of the electric motor.

[0033] In order to facilitate description, the drawings of the present disclosure accordingly simplify or omit components commonly used in the art, such as external connection lines and other components that are irrelevant to the description of the present disclosure. These omitted or simplified components do not affect the understanding of the content of the present disclosure by a person skilled in the art.

[0034] Fig. 1 shows a partial sectional view of a drivetrain system according to an exemplary embodiment of the present disclosure.

[0035] As shown in Fig. 1, the drivetrain system comprises an electric motor 100 and a transmission shaft 20; the transmission shaft 20, for example, may be an input shaft of a gearbox. The electric motor 100 includes a rotor 110 and a stator 120. The electric motor shaft 10 is located at the axis centre of the rotor 110 and rotates around a rotation axis X together with the rotor 110. The transmission shaft 20 is coaxial with the electric motor shaft 10 of the electric motor 100, and is rotationally coupled therewith, such that relative rotation does not occur between the electric motor shaft 10 and the transmission shaft 20. In other words, the rotation of the electric motor shaft 10 around the rotation axis X drives the transmission shaft 20 to rotate together around the rotation axis X, thereby transmitting torque from the electric motor 100 to the transmission shaft 20.

[0036] A cooling fluid circulates in the drivetrain system; the cooling fluid may cool various parts of the electric motor 100, and may also cool and / or lubricate other components such as a gearbox. A flow passage of the cooling fluid between the electric motor 100 and the other components of the drivetrain system is defined by the transmission shaft 20 and the electric motor shaft 10. When the cooling fluid flows, the electric motor 100 is generally located downstream of the transmission shaft 20; that is, the cooling fluid enters the electric motor 100 from the transmission shaft 20 through the electric motor shaft 10 of the electric motor 100. Referring to Figs. 1 and 2, the transmission shaft 20 may be provided with a second central hole 21, and the electric motor shaft 10 may be provided with a first central hole 11. The transmission shaft 20 is inserted into the first central hole 11 of the electric motor shaft 10. Thus, the cooling fluid can flow from the second central hole 21 of the transmission shaft 20 into the first central hole 11 of the electric motor shaft 10. Next, the cooling fluid is sprayed from the electric motor shaft 10 in a radial direction, under the driving of centrifugal force, and reaches various components of the electric motor 100 to cool them.

[0037] Among the various components of the electric motor 100, the stator 120 includes a winding 121 in which a relatively large alternating current flows, for generating an alternating magnetic field that drives the rotor 110 to rotate. Therefore, the winding 121 of the stator 120 is one of the main heat-generating components of the electric motor 100. As shown in Fig. 1, the winding 121 includes ends that extend beyond the main body of the stator 120. When cooling the winding 121, optionally, the cooling fluid can be sprayed to an end of the winding 121, and then flow in the axial direction to cool the entire winding 121.

[0038] Referring to the schematic drawing shown in Fig. 2, the electric motor shaft 10 further comprises a first cooling hole 12 and a second cooling hole 13 that communicate with the first central hole 11. The first cooling hole 12 and the second cooling hole 13 are respectively arranged at a first end 10a and a second end 10b of the electric motor shaft 10. The axial position of the first end 10a is further away from the transmission shaft 20, and the first end corresponds to an end of the winding 121 that is remote from the transmission shaft 20. The second end 10b is opposite the first end 10a and is nearer the transmission shaft 20, and corresponds to an end of the winding 121 that is near the transmission shaft 20. Thus, the cooling fluid can spray from the first central hole 11 of the electric motor shaft 10, through the first cooling hole 12 and the second cooling hole 13, respectively, to both ends of the winding 121.

[0039] When the drivetrain system operates, the cooling fluid flows from the second central hole 21 of the transmission shaft 20 into the first central hole 11 of the electric motor shaft 10. Next, the cooling fluid first sprays from the second cooling hole 13 near the transmission shaft 20 towards the end of the winding 121 near the transmission shaft 20, and then sprays from the first cooling hole 12 remote from the transmission shaft 20 towards the end of the winding 121 remote from the transmission shaft 20. The first cooling hole 12 remote from the transmission shaft 20 is generally arranged away from an inlet by which cooling fluid flows from the second central hole 21 into the first central hole 11. In this way, the amount of cooling fluid sprayed from the first cooling hole 12 is less than the amount of cooling fluid sprayed from the second cooling hole 13. However, when the electric motor 100 operates, the amounts of heat emitted at the two ends of the winding 121 are basically the same. Such a difference in the amounts of cooling liquid sprayed causes the cooling effects for different parts of the winding 121 to be different.

[0040] To solve the above problem, as shown in Fig. 2, the electric motor shaft 10 of the present disclosure is provided with a separating part 14 in the first central hole 11, the separating part 14 separating the first central hole 11 into a first section Ila that communicates with the first cooling hole 12 and a second section 11b that communicates with the second cooling hole 13. The transmission shaft 20 comprises a first communicating hole 22 and a second communicating hole 23, the first communicating hole 22 connecting the second central hole 21 with the first section Ila, and the second communicating hole 22 connecting the second central hole 21 with the second section 11b. The separating part 14 can obstruct the flow of cooling fluid between the first section Ila and the second section 11b. Thus, the cooling fluid that flows through the first communicating hole 22 into the first section Ila can only spray from the first cooling hole 12, and the cooling fluid that flows through the second communicating hole 23 into the second section 11b can only spray from the second cooling hole 13. Controlling the amount of cooling fluid that flows out from the second central hole 21 through the first communicating hole 22 and the second communicating hole 23 is sufficient for regulating the amounts of cooling fluid that are sprayed to the two ends of the winding 121.

[0041] Optionally, the separating part 14 has an annular form that extends from an inner wall of the first central hole 11 of the electric motor shaft 10 towards the centre, and does not completely separate the first central hole 11 : that the flow of cooling fluid between the first section Ila and the second section 11b can be obstructed suffices. At the first central hole 11 of the electric motor shaft 10, the transmission shaft 20 extends past the separating part 14, and a certain radial gap is provided between the separating part 14 and the transmission shaft 20. In the embodiment shown in Fig. 2, the separating part 14 is an annular separating rib that extends from the inner wall of the first central hole 11 of the electric motor shaft 10 towards the centre. During manufacture of the electric motor shaft 10, two sections of the electric motor shaft 10 may be first manufactured, and the two sections are welded together to form the electric motor shaft 10. The separating part 14 is formed by an annular plate embedded between the two sections during welding. Optionally, two ends of the electric motor shaft 10 are welded together by friction welding, and the separating part 14 is formed by a protrusion that is formed on the weld from the friction welding.

[0042] The separating part 14 is near the second end 10b of the electric motor shaft 10. Thus, a shorter length of the transmission shaft 20 can be inserted into the first central hole 11 to pass the extending part 14, reducing assembly difficulty of the transmission shaft 20 and the electric motor shaft 10. It will be understood that the separating part 14 may also be arranged near the first end 10a of the electric motor shaft 10. Here, the transmission shaft 20 must be inserted into the first central hole 11 by a longer length in order to pass the separating part 14.

[0043] For the electric motor 100 of which the amounts of heat emitted at the two ends of the winding 121 are basically the same, the amounts of cooling fluid sprayed from the first cooling hole 12 and the second cooling hole 13 are optionally basically equal. For this, the transmission shaft 20 is constructed such that the axial positions of the first communicating hole 22 and the second communicating hole 23 communicating with the second central hole 21 are near each other or the same, such that the cooling fluid flows out from the first communicating hole 22 and the second communicating hole 23 with the same fluid pressure. As shown in the example in Fig. 2, the first communicating hole 22 and the second communicating hole 23 are slanted holes that form a certain angle with the radial direction, and the two communicate with the second central hole 21 at the same axial position. Optionally, the first communicating hole 22 and the second communicating hole 23 communicate with the second central hole 21 at the axial position of the separating part 14. The slanted structures of the first communicating hole 22 and the second communicating hole 23 allow the length by which the transmission shaft 20 extends past the separating part 14 to be shorter, while ensuring that the cooling fluid that flows out from the first communicating hole 22 enters the first section Ila, and the cooling fluid that flows out from the second communicating hole 23 enters the second section 11b. The first communicating hole 22 and the second communicating hole 23 may further communicate with the end of the second central hole 21, to further reduce the length of the transmission shaft 20.

[0044] In an optional embodiment not shown, the first communicating hole 22 and the second communicating hole 23 may be radial holes, the axial positions thereof respectively being located at two sides of the separating part 14, to respectively lead to the first section Ila and the second section 11b. The first communicating hole 22 and the second communicating hole 23 may be arranged near the separating part 14, for example next to the separating part 14 on two sides.

[0045] In the example shown in Fig. 2, the diameters of the first communicating hole 22 and the second communicating hole 23 are the same, and the diameters of the first cooling hole 12 and the second cooling hole 13 are also the same. This helps approximately equal amounts of cooling fluid to be sprayed to the two ends of the winding 121. Of course, when it is needed for unequal amounts of cooling fluid to be sprayed toward the two ends of the winding 121, the diameters of the first communicating hole 22 and the second communicating hole 23 may be different, and the diameters of the first cooling hole 12 and the second cooling hole 13 may also be different.

[0046] According to another aspect of the present disclosure, a vehicle is provided, the vehicle comprising the drivetrain system as previously described. The vehicle may be an electrified vehicle, such as a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a range extended EV and a fuel cell electric vehicle (FCEV). The vehicle may also be a hydrogen- powered vehicle.

[0047] Certain features, structures or characteristics in one or more embodiments of the present disclosure may be combined appropriately.

[0048] The above is a description of the present disclosure and should not be construed as a limitation thereon. Although several exemplary embodiments of the present disclosure have been described, those of ordinary skill in the art will readily understand that many modifications may be made to the exemplary embodiments without departing from the novel teaching and advantages of the present disclosure. Therefore, all such modifications are intended to be included in the scope of the present disclosure as defined by the claims. It should be understood that the above is a description of the present disclosure, that the present disclosure should not be deemed to be limited to the specific embodiments disclosed herein, and that modifications to the embodiments disclosed herein and other embodiments are intended to be included within the scope of the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. A flow path assembly for a drivetrain system, the flow path assembly comprising: an electric motor shaft (10), capably rotating around a rotation axis (X), comprising a first end (10a) and a second end (10b) that is opposite the first end; and a transmission shaft (20), which is in transmission connection with the electric motor shaft (10) and is coaxial therewith, wherein the electric motor shaft (10) comprises a first central hole (11) that forms a part of a flow path, and a first cooling hole (12) and a second cooling hole (13) that communicate with the first central hole (11), the first cooling hole (12) being near the first end (10a), and the second cooling hole (13) being near the second end (10b), wherein a separating part (14) is further provided in the first central hole (11) of the electric motor shaft (10), the separating part (14) separating the first central hole (11) into a first section (Ila) that communicates with the first cooling hole(12) and a second section (11b) that communicates with the second cooling hole(13), and wherein the transmission shaft (20) comprises a second central hole (21) that forms a part of the flow path, and a first communicating hole (22) and a second communicating hole (23), the first communicating hole (22) connecting the second central hole (21) with the first section (Ila), and the second communicating hole (22) connecting the second central hole (21) with the second section (11b).

2. The flow path assembly according to claim 1, characterized in that the transmission shaft (20) is inserted into the first central hole (11) of the electric motor shaft (10), and extends past the separating part (14).

3. The flow path assembly according to claim 2, characterized in that a certain radial gap is provided between the separating part (14) and the transmission shaft (20).

4. The flow path assembly according to claim 2 or 3, characterized in that the first communicating hole (22) and the second communicating hole (23)are radial holes with axial positions located on two sides of the separating part (14).

5. The flow path assembly according to claim 2 or 3, characterized in that the first communicating hole (22) and / or the second communicating hole (23) is a slanted hole that forms a certain angle with a radial direction.

6. The flow path assembly according to claim 5, characterized in that the first communicating hole (22) and the second communicating hole (23) communicate with the second central hole (21) at the same axial position.

7. The flow path assembly according to claim 6, characterized in that the first communicating hole (22) and the second communicating hole (23) communicate with the second central hole (21) at the axial position of the separating part (14).

8. The flow path assembly according to claim 6, characterized in that the first communicating hole (22) and the second communicating hole (23) communicate with an end of the second central hole (21).

9. The flow path assembly according to claim 2, characterized in that the diameter of the first communicating hole (22) is the same as the diameter of the second communicating hole (23), or the diameter of the first communicating hole (22) is different to the diameter of the second communicating hole (23).

10. The flow path assembly according to any one of claims 1 to 3, characterized in that the separating part (14) is arranged to be near the first end (10a) or the second end (10b) of the electric motor shaft (10).

11. The flow path assembly according to any one of claims 1 to 3, characterized in that the separating part (14) is an annular separating rib that extends from an inner wall of the first central hole (11) of the electric motor shaft (10) towards the centre.

12. A drivetrain system, characterized in that the drivetrain system comprises the flow path assembly according to any one of claims 1 to 11.

13. A vehicle, characterized in that the vehicle comprises the drivetrain system according to claim 12.

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