WO2021208972A1

WO2021208972A1 - Drivetrain system for an electrified vehicle

Info

Publication number: WO2021208972A1
Application number: PCT/CN2021/087252
Authority: WO
Inventors: Yejin JIN; Kai Chen; Guoqiang Sun
Original assignee: Valeo Powertrain (shanghai) Co., Ltd.
Priority date: 2020-04-15
Filing date: 2021-04-14
Publication date: 2021-10-21
Also published as: CN113531096A; EP4136364A1; JP2023521461A; KR20230004491A

Abstract

The present disclosure relates to a drivetrain system for an electrified vehicle. The drivetrain system comprises an electric motor configured for providing with drive power and comprising a rotor and a driveshaft driven by the rotor; a speed reducer configured for speed-reducing and increasing torque received from the driveshaft, the speed reducer comprising an intermediate transmission shaft at least two reduction gear sets; a differential apparatus configured for distributing speed-reduced drive power to driven wheels; a disconnectable clutch provided onto the intermediate transmission shaft and configured for providing with interruptive transmission of the drive power between the electric motor and the differential apparatus; and a pumping component configured for transferring lubricant to provide with active and continuous lubrication for the speed reducer, minimizing the level of lubricant in which the differential apparatus is plunged.

Description

DRIVETRAIN SYSTEM FOR AN ELECTRIFIED VEHICLE

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to a drivetrain system for an electrified vehicle.

BACKGROUND

The trend towards designing and building fuel efficient, low emission vehicles has increased dramatically, this trend driven by concerns over the environment as well as increasing fuel costs. At the forefront of this trend has been the development of electrified vehicles, such as BEV, HEV, PHEV, Range extended EV, Fuel Cell etc., electrified vehicles that combine a relatively efficient combustion engine with an electric drive motor. Electrified vehicles can include rotating components, particularly the drivetrain system, that needs to be lubricated to achieve a long service life of the rotating components. Generally, in order to achieve an adequate supply of lubricant, the differential comprised of the drivetrain system includes a reservoir containing lubricant to be transferred to the rotating components all over the drivetrain system for lubrication via at least one rotating component that is comprised of the differential and contacts with the lubricant. However, the lubricant shall be always kept in a high level in the reservoir of the differential, there would be high churning loss of the differential as well as differential splash loss during the cruising phase of the vehicle.

Therefore, it would be desirable if any improvements on lubrication design for the drivetrain system for electrified vehicles could be provided at least with simple configuration, low energy consumption or loss, and low cost.

SUMMARY OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In accordance with one aspect disclosed herein, a drivetrain system for an electrified vehicle is provided. The drivetrain system comprises an electric motor configured for providing with drive power and comprising a rotor and a driveshaft driven by the rotor; a speed reducer configured for speed-reducing and increasing torque received from the driveshaft, the speed reducer comprising an intermediate transmission shaft; a differential apparatus configured for distributing speed-reduced drive power to driven wheels; a disconnectable clutch provided onto the intermediate transmission shaft and configured for providing with interruptive transmission of the drive power between the electric motor and the differential apparatus; and a pumping component configured for transferring lubricant so as to provide with active and continuous lubrication for the speed reducer, minimizing the level of lubricant in which the differential apparatus is plunged.

In one embodiment, the speed reducer comprises a plurality of reduction gear sets with different ratios and connecting with the electric motor and the differential apparatus.

In one embodiment, the speed reducer further comprises a first set of reduction gears, comprising a first driving gear connected to the electric motor and a first driven gear connected to the intermediate shaft; and a second set of reduction gears, comprising a second driving gear connected to the intermediate shaft and a second driven gear connected to the differential apparatus.

In one embodiment, the second driving gear of the second set of reduction gears or the first driven gear of the first set of reduction gears is solidly linked to one of the disconnectable clutch and the other disconnectable clutch is solidly linked to the intermediate shaft.

In one embodiment, the drivetrain system further comprises a bearing. The bearing is configured for supporting the disconnectable clutch, the second driving gear or the first driven gear is rolling on the bearings coaxially disposed on the intermediate transmission shaft.

In an alternatively embodiment, the speed reducer comprises at least three gear sets with different ratios and connecting with the electric motor and the differential apparatus.

In one embodiment, the disconnectable clutch is coaxially provided to one of the at least three reduction gear sets that is closest to the differential apparatus or closest to the electric motor, one gear of the at least three reduction gear sets is solidly linked to one part of the disconnectable clutch.

In one embodiment, the drivetrain system further comprises a bearing for supporting the disconnectable clutch, one gear of the at least three reduction gear sets is coaxially rolling on the bearing.

In one embodiment, the drivetrain system further comprises an actuator. The actuator is configured for providing the disconnectable clutch with an engagement and non-engagement force.

In one embodiment, the pumping component is mechanically integrated on and driven by the driveshaft or the intermediately transmission shaft.

In an alternatively embodiment, the pumping component is electrically driven by another electric motor.

In one embodiment, the pumping component is a gerotor pump.

In one embodiment, the disconnectable clutch is a dog clutch.

These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following detailed description. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 is a schematic view of a drivetrain system in accordance with an exemplary aspect of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT

Reference will now be made to in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “a” , “an” and “the” are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. The terms “comprising” , “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The terms “first” and “second” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of individual components.

Referring now to the drawing, FIG 1 shows a drivetrain system 100 in accordance with one embodiment of the present disclosure. More particularly, the drivetrain system 100 is generally integrated with an inverter (not shown) , an electric motor 1, a speed reducer 2 and a differential apparatus 3. Specifically, the electric motor 1 is contained in one housing, and the speed reducer 2 and the differential apparatus 3 are contained in another housing. The two housings can be one-piece or be formed by an assembly of housing sub-parts together. The two housings can be rigidly fixed together, for example by means of screws. A sealing wall is here provided between the two housings.

The electric motor 1 can be a synchronous motor or an asynchronous motor. When it is a synchronous motor, it may include a wound rotor or a permanent magnet rotor. The nominal power supplied by the electric motor can be between 10 KW and 300KW, for example, of the order of 15 KW, for a nominal supply voltage of 48V to 350V, or up to 800V for higher power. In the case of an electric motor adapted to a high voltage supply, the nominal power supplied by this electric motor may be 300 KW. In the illustrated embodiment, the electric motor 1 is a synchronous motor with permanent magnets, providing a nominal power between 10 KW and 300 KW. The electric motor 1 can include a stator with a three-phase winding, or a combination of two three-phase windings or five-phase windings. Furthermore, the electric motor 1 can include a driveshaft 11 driven by the electrical power generated from the electromagnetic effect of a rotor (not shown) and a stator (not shown) included in the electric motor 1.

The inverter is attached by the electrical wires to the electric motor 1. The inverter converts the direct current ( “DC” ) supplied by an electrical energy storage unit (not shown) providing with the electric energy of a nominal voltage to the alternating current ( “AC” ) used to the electric motor 1. The inverter can be, without limitation, field effect transistors ( “FETs” ) , metal oxide semiconductor field effect transistors ( “MOSFETs” ) or insulated gate bipolar transistors ( “IGBTs” ) . In the case of a nominal supply voltage of 48V, the inverter can be MOSFET transistors. In the case of a supply voltage corresponding to a high voltage, the inverter can be IGBTs.

The speed reducer 2 is coupling to the electric motor 1. The speed reducer 2 can transform the electric motor’s high speed, low torque to low speed, high torque. The speed reducer 2 may comprise a plurality of reduction gear sets with different ratios and connecting with the electric motor 1 and the differential apparatus 3, with one of the gears driven by the electric motor 1 for instance, for torque increasing via speed reduction. The speed reducer 2 may further comprise an intermediate transmission shaft 21, linking a gear driven by the driveshaft shaft 11 and another gear of larger diameter coupled to the differential apparatus 3 for distributing speed-reduced drive power to driven wheels 4.

For the embodiment depicted, the intermediate transmission shaft 21 is rotatable supported in the housing by means of two bearings 9 provided in the form of rolling contact bearings each bearing being placed at ends of the intermediate transmission shaft 21.

Further, the speed reducer 2 may comprise a plurality of reduction gear sets with different ratios and connecting with the electric motor and the differential apparatus. In one embodiment, the speed reducer 2 may comprise at least three gear sets, a disconnectable clutch 6 can be coaxially provided to one of the at least three reduction gear sets that is closest to the differential apparatus or closest to the electric motor, so as to provide with interruptive transmission of the drive power between the electric motor 1 and the differential apparatus 3. In one embodiment, one of the gears of the at least three reduction gear sets is solidly linked to one part of the disconnectable clutch.

In the illustrated embodiment, the speed reducer 2 comprises two reduction gears sets, which is a first set of reduction gears comprising a first driving gear 22 connected to the electric motor 1 and a first driven gear 23 connected to the intermediate transmission shaft 21, the first driving gear 22 and driven gear 23 being in engagement with each other; and a second set of reduction gears comprising a second driving gear 24 connected to the intermediate transmission shaft 21 and a second driven gear 25 connected to the differential apparatus 3, the second driving gear 24 and driven gear 25 being in engagement with each other.

In the illustrated embodiment, a pair of disconnectable clutches 6 is provided for providing with interruptive transmission of the drive power between the electric motor 1 and the differential apparatus 3. One of the disconnectable clutches 62 is disposed onto the intermediate transmission shaft 21, further solidly linking with the second driving gear 24. The other one of the disconnectable clutches 61 is solidly linked to the intermediate transmission shaft shaft 21. In one embodiment, the one of the disconnectable clutches 62 can be further solidly linking with the first driven gear 23. When the pair of the disconnectable clutches 6 is in engagement, driving power of the electric motor 1 can be transferred to the vehicle via the speed reducer 2 and the clutch 6 to provide an auxiliary driving power.

A bearing 7 is further provided for supporting the disconnectable clutch 6, the second driving gear 24 is rolling on the bearing 7 coaxially disposed on the intermediate transmission shaft 21. In one embodiment, the first driven gear 23 will be rolling on the bearing 7 if the clutch 6 is solidly linking with the first driven gear 23.

An actuator 8 is further provided for electrically providing the disconnectable clutch 6 with an engagement and non-engagement force. Particularly, the actuator 8 is disposed on the intermediate transmission shaft 21 and mechanically connected with the clutch 61. In one embodiment, the actuator 8 can be a solenoid.

For the embodiment depicted, the clutch 6 is a dog clutch comprising a fixed tooth 61 solidly linking to the first driven gear 23 or to the second driving gear 24, and a movable tooth 62 solidly linking to the intermediate transmission shaft 21. In the circumstance that requires an auxiliary driving power to the vehicle, the actuator 8 will be power on and provide with an engagement force to let the movable tooth 62 engage with the fixed tooth 61, so that the fixed tooth 61 can rotate the movable tooth 62, further drive the intermediate transmission shaft 21 where the

teeth

61, 62 are disposed to rotate, and finally drive the differential apparatus 3 via the reduction gears to provide drive power to the vehicle.

Still in the illustrated embodiment, a pumping component 5 is further provided for transferring lubricant throughout the drivetrain system 100, particularly for providing with active lubrication for the speed reducer 2 via pumping the lubricant in a reservoir (not shown) contained in the differential apparatus 3. In the circumstance that the disconnectable clutch 6 is in non-engagement state, the pumping component 5 would be always working, i.e., keep pumping the lubricant from the differential apparatus 3 so that the electric motor can be continuously cooled down.

In one embodiment, the pumping component 5 may be an electrical pump which can be electrically driven by anther electric motor (not shown) . In one embodiment, the pumping component 5 may be a mechanical pump which can be mechanically integrated on and driven by the driveshaft 11 or the intermediate transmission shaft 21. For the embodiment depicted, the pumping component 5 is mechanically integrated on and driven by the intermediately transmission shaft 21 so that when the disconnectable clutch 6 is in non-engagement state the pumping component 5 can be always actuated with the torque from the electric motor 1 at a required speed, i.e., a low speed, to continue the cooling of the electric motor and lubrication.

According to the drivetrain system 100 as provided by the present disclosure, the use of the intermediate shaft for the disconnect allows less shock during the engaging of the disconnect for a high reduction ratio gearbox, quicker synchronization time during the engaging for a high RPM electric motor with high reduction ratio gearbox and lower force of the solenoid for the disconnect. Furthermore, since the intermediate shaft is not transferring the torque to the differential, when the clutch is disconnected, there will not be electrical energy loss for the electric motor flux weakening. Thanks to the active lubrication system, the oil level is kept at low level minimizing the loss coming from the churning of lubricant by the differential.

This written description uses examples to disclose the embodiments of the present disclosure, including the best mode, and also to enable any person skilled in the art to practice embodiments of the present disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the embodiments described herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

A drivetrain system for an electrified vehicle, comprising:

an electric motor, configured for providing with drive power, comprising a rotor and a driveshaft driven by the rotor;

a speed reducer, configured for speed-reducing and increasing torque received from the driveshaft, comprising an intermediate transmission shaft and at least two reduction gear sets;

a differential apparatus configured for distributing speed-reduced drive power to driven wheels;

a disconnectable clutch, provided onto the intermediate transmission shaft, configured for providing with interruptive transmission of the drive power between the electric motor and the differential apparatus; and

a pumping component configured for transferring lubricant to provide with active and continuous lubrication for the speed reducer.
The drivetrain system of claim 1, wherein one gear of the differential apparatus is solidly linked to the intermediate transmission shaft, which actuates the pumping component with the torque from the electric motor when the disconnectable clutch is in non-engagement.
The drivetrain system of claim 1, wherein the speed reducer comprises two reduction gear sets with different ratios connecting with the electric motor and the differential apparatus, the two reduction gear sets comprise:

a first set of reduction gears, comprising a first driving gear connected to the electric motor and a first driven gear connected to the intermediate transmission shaft; and

a second set of reduction gears, comprising a second driving gear connected to the intermediate transmission shaft and a second driven gear connected to the differential apparatus;

wherein the second driving gear of the second set of reduction gears or the first driven gear of the first set of reduction gears is solidly linked to one part of the disconnectable clutch, and the intermediate transmission shaft is solidly linked to the other part of disconnectable clutch.
The drivetrain system of claim 3, wherein the drivetrain system further comprises a bearing for supporting the disconnectable clutch, the second driving gear or the first driven gear is rolling on the bearing coaxially disposed on the intermediate transmission shaft.
The drivetrain system of claim 1, wherein the speed reducer comprises at least three gear sets with different ratios and connecting with the electric motor and the differential apparatus, the disconnectable clutch is coaxially provided to one of the at least three reduction gear sets that is closest to the differential apparatus or closest to the electric motor, one gear of the at least three reduction gear sets is solidly linked to one part of the disconnectable clutch.
The drivetrain system of claim 5, wherein the drivetrain system further comprises a bearing for supporting the disconnectable clutch, one gear of the at least three reduction gear sets is coaxially rolling on the bearing.
The drivetrain system of claim 1, wherein the drivetrain system further comprises an actuator configured for providing the disconnectable clutch with an engagement and non-engagement force.
The drivetrain system of claim 1, wherein the pumping component is mechanically integrated on and driven by the driveshaft or the intermediate transmission shaft, or electrically driven by another electric motor.
The drivetrain system of claim 1, wherein the pumping component is a gerotor pump.
The drivetrain system of claim 1, wherein the disconnectable clutch is a dog clutch.