Drivetrain systems for electric vehicles

Abstract

To provide a drive train system for an electric vehicle having a lubrication structure enabling cost reduction while reducing energy consumption or loss with a simple configuration.SOLUTION: A drive train system includes: an electric motor configured to provide driving force, the electric motor including a rotor and a drive shaft driven by the rotor; a reduction gear configured to reduce speed received by the drive shaft and increase torque, the reduction gear including an intermediate transmission shaft with a hollow axial passage; and a pump component configured to transfer a lubricant. The pump component is mechanically built in the intermediate transmission shaft, is driven by the intermediate transmission shaft, and includes a plurality of passages for supplying the lubricant to the axial passage of the intermediate transmission shaft and the component disposed in the intermediate transmission shaft.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD Embodiments of the present disclosure relate generally to drivetrain systems for electric vehicles, and more particularly to integrated lubrication circuits for drivetrain systems. [Background technology]

[0002] There has been a significant trend toward designing and manufacturing fuel-efficient, low-emission vehicles, driven by environmental concerns and rising fuel costs. At the forefront of this trend is the development of electric vehicles, such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), range-extended electric vehicles (RVs), and fuel cell electric vehicles, which combine relatively efficient combustion engines with electric drive motors. Electric vehicles may contain rotating parts, particularly drivetrain systems, that require lubrication to achieve a long service life. Typically, a differential included in a drivetrain system includes a lubricant reservoir to ensure adequate lubrication. The lubricant is transported to the entire drivetrain system via at least one rotating part included in the differential that comes into contact with the lubricant. However, the lubricant must always be maintained at a high level in the differential reservoir, which can result in high churning losses at the differential wheels and high power losses throughout the drivetrain system. Alternatively, nozzles are typically used to actively lubricate certain rotating parts. This would otherwise incur additional costs and processes.

[0003] It would therefore be desirable to have improvements in the lubrication design of drivetrain systems for electric vehicles that are at least simple in construction, provide low energy consumption or loss, and are low cost. Summary of the Invention

[0004] Aspects and advantages of the invention will be set forth in the description that follows, or may be obvious from the description, or may be learned by practice of the invention.

[0005] According to one aspect of the present disclosure, there is provided a drivetrain system for an electric vehicle, the drivetrain system including: an electric motor configured to provide driving force, the electric motor including a rotor and a drive shaft driven by the rotor; a reducer configured to reduce speed and increase torque received from the drive shaft, the reducer including an intermediate transmission shaft having a hollow axial passage; and a pump component configured to pump lubricant. The pump component is mechanically integrated into and driven by the intermediate transmission shaft, and includes a plurality of passages for supplying lubricant to the axial passage of the intermediate transmission shaft and to the components disposed on the intermediate transmission shaft.

[0006] In one embodiment, the plurality of passages comprises at least one lateral passage for supplying lubricant to the hollow axial passage of the intermediate transmission shaft and at least one longitudinal passage for supplying lubricant to the components disposed on the intermediate transmission shaft.

[0007] In one embodiment, the pump component further comprises a pump shaft coaxially mounted on the intermediate transmission shaft and configured to actuate the pump component for supplying lubricant.

[0008] In one embodiment, the plurality of passages further comprises an axial passage within the pump shaft, the axial passage in fluid communication with the hollow axial passage of the intermediate transmission shaft.

[0009] In one embodiment, the axial passage is further in fluid communication with at least one of the lateral passages.

[0010] In one embodiment, the pump shaft is actuated by a coupling piece fixedly connected to the intermediate transmission shaft and the pump shaft.

[0011] In one embodiment, the coupling part is a sleeve.

[0012] In one embodiment, the coupling component is a one-way clutch configured to always rotate in one direction.

[0013] In one embodiment, the coupling part comprises a connection that prevents lubricant from returning from the hollow axial passage of the intermediate transmission shaft or from leaking from the hollow axial passage of the intermediate transmission shaft.

[0014] In one embodiment, at least one of the longitudinal passages is in fluid communication with a circular gap provided between the pump shaft and the intermediate transmission shaft, so that lubricant can be supplied to the components arranged on the intermediate transmission shaft through the circular gap.

[0015] In one embodiment, the circular gap is provided laterally adjacent to a bearing supporting the intermediate transmission shaft, so that lubricant can be supplied to the bearing through the circular gap.

[0016] In one embodiment, the intermediate transmission shaft further comprises at least one radial passage, the at least one radial passage being in fluid communication with the hollow axial passage to transport lubricant to the components disposed on the intermediate transmission shaft.

[0017] In one embodiment, the pump component further comprises a cavity configured to store the lubricant supplied by a plurality of the passages.

[0018] In one embodiment, at least one of the lateral passages extends radially from the cavity to transport the lubricant stored in the cavity, and at least one of the longitudinal passages extends axially from the cavity to transport the lubricant stored in the cavity.

[0019] In one embodiment, the pump component is a gerotor pump.

[0020] In one embodiment, the pump component is configured to deliver lubricant in one direction when the pump component is rotationally driven.

[0021] In one embodiment, the drivetrain system further comprises a differential configured to distribute reduced driving force to a driven mechanical load, and a disengageable clutch provided on the intermediate transmission shaft configured to provide decoupling of the driving force between the electric motor and the actuator, and the pump component transports lubricant to provide active lubrication to the reducer and minimizes the level of lubricant entering the actuator.

[0022] In one embodiment, the drivetrain system further comprises an actuator coaxially disposed with the disconnectable clutch and configured to mechanically provide an engaging and disengaging force to the disconnectable clutch.

[0023] In one embodiment, the actuator is a solenoid.

[0024] In one embodiment, the actuator is cooled by the lubricant from at least one radial passage in fluid communication with a hollow axial passage of the intermediate transmission shaft.

[0025] 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.

[0026] 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 this specification, including reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram of a drivetrain system according to an exemplary embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view of the intermediate transmission shaft of the drive train system according to FIG. [Figure 3] 3 is another cross-sectional view of the intermediate transmission shaft of the drivetrain system according to FIG. 1, showing the transverse passages for supplying lubricant to the hollow axial passage of the intermediate transmission shaft. [Figure 4] 4 is another cross-sectional view of the intermediate transmission shaft of the drive train system according to FIG. 1, showing the radial passages of the intermediate transmission. DETAILED DESCRIPTION OF THE INVENTION

[0028] Embodiments of the present invention are presented in detail below, examples of which are illustrated in the accompanying drawings. The detailed description uses symbol and word designations to refer to features in the figures. Like or similar designations in the drawings and description are used to refer to like or similar parts of the present invention. As used herein, the terms "a," "an," and "the" are intended to mean that there are one or more elements, unless otherwise specified. The terms "comprise," "include," and "have" 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 element from another and are not intended to denote the location or importance of individual elements.

[0029] Reference is now made to the drawings. The same reference numerals refer to the same elements throughout the drawings. FIGS. 1 to 4 show a drivetrain system 100 according to an embodiment of the present disclosure. More specifically, the drivetrain system 100 generally integrates an inverter (not shown), an electric motor 1, a reducer 2, and a differential 3. Specifically, the electric motor 1 is housed in one housing, and the reducer 2 and the differential 3 are housed in another housing. The two housings may be one piece, or may be formed by assembling subparts of the housings together. The two housings may be firmly fixed together using, for example, screws. In this example, a sealing wall is provided between the two housings.

[0030] The electric motor 1 may be a synchronous motor or an asynchronous motor. If it is a synchronous motor, it may include a wound rotor or a permanent magnet rotor. The nominal power provided by the electric motor may be 10 kW to 300 kW, for example, approximately 15 kW. The nominal supply voltage may be 48 V to 350 V, or up to 800 V for higher power. For electric motors compatible with high-voltage supplies, the nominal power provided by the 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 of 10 kW to 300 kW. The electric motor 1 may include a stator with a three-phase winding, a combination of two three-phase windings, or a five-phase winding. Furthermore, the electric motor 1 may include a drive shaft 11 driven by power generated from the electromagnetic effect between a rotor (not shown) and a stator (not shown) included in the electric motor 1.

[0031] The inverter is attached to the electric motor 1 by electrical wires. The inverter converts direct current ("DC") supplied by an electrical energy storage unit (not shown), which provides electrical energy at a nominal voltage, into alternating current ("AC") used by the electric motor 1. The inverter may be, but is not limited to, a field effect transistor ("FET"), a metal oxide semiconductor field effect transistor ("MOSFET"), or an insulated gate bipolar transistor ("IGBT"). For a nominal supply voltage of 48V, the inverter may be a MOSFET transistor. For supply voltages corresponding to higher voltages, the inverter may be an IGBT.

[0032] The reducer 2 is coupled to the electric motor 1. The reducer 2 can convert the high speed and low torque of the electric motor into low speed and high torque. The reducer 2 may include multiple reduction gear sets with different ratios connected to the electric motor 1 and the differential 3. The reducer 2, the electric motor 1, and the differential 3 are connected, for example, by one of the gears driven by the electric motor 1 to increase torque by reducing speed. The reducer 2 may further include an intermediate transmission shaft 21. The intermediate transmission shaft 21 connects a drive gear driven by the drive shaft 11 to another larger gear coupled to the differential 3 for distributing reduced driving force to the driven wheels 4.

[0033] In the illustrated embodiment, the reducer 2 includes two reduction gear sets including a first set of reduction gears and a second set of reduction gears. The first set of reduction gears includes a first drive gear 22 connected to the electric motor 1 and a first driven gear 23 connected to the intermediate shaft 21, and the first drive gear 22 and the first driven gear 23 are engaged with each other. The second set of reduction gears includes a second drive gear 24 connected to the intermediate shaft 21 and a second driven gear 25 connected to the differential 3, and the second drive gear 24 and the second driven gear 25 are engaged with each other.

[0034] In the illustrated embodiment, a disengageable clutch 6 is provided to provide drive disconnection between the electric motor 1 and the differential 1. The disengageable clutch 6 is disposed on the intermediate transmission shaft 21 and is further rigidly coupled to the second drive gear 24. In one embodiment, the disengageable clutch 6 may also be rigidly coupled to the first driven gear 23. When the disengageable clutch 6 is engaged, the drive force of the electric motor 1 is transmitted to the vehicle via the reducer 2 and the clutch 6 to provide supplemental drive force.

[0035] Additionally, a bearing 7 is provided to support the disconnectable clutch 6. The second drive gear 24 rotates in the bearing 7, which is coaxially disposed on the intermediate transmission shaft 21. In one embodiment, when the clutch 6 is rigidly coupled to the first driven gear 23, the first driven gear 23 rotates in the bearing 7.

[0036] Furthermore, an actuator 8 is provided to electrically provide an engaging force and a disengaging force to the disengageable clutch 6. Specifically, the actuator 8 is disposed on the intermediate transmission shaft 21 and is electrically connected to the clutch 6. In one embodiment, the actuator 8 may be a solenoid. When supplemental driving force for the vehicle is required, the actuator 8 is turned on and provides an engaging force to engage the disengageable clutch 6, which then drives and rotates the intermediate transmission shaft 21 on which the disengageable clutch 6 is disposed, ultimately driving the operating device 3 via a reduction gear to provide driving force to the vehicle.

[0037] Furthermore, in the illustrated embodiment, a pump element 5 is further provided to transfer lubricant throughout the drivetrain system 100. Specifically, its purpose is to provide active lubrication to the reducer 2 by pumping lubricant from a reservoir (not shown) housed in the differential 3. When the disengageable clutch 6 is disengaged, the pump element 5 will always be active, i.e., it will continue to pump lubricant from the actuator 3. This allows the electric motor to be continuously cooled.

[0038] In one embodiment, pump component 5 may be a mechanical pump, for example a gerotor pump, which may be mechanically integrated into and driven by intermediate transmission shaft 21. Furthermore, when pump component 5 is driven to rotate clockwise or counterclockwise, pump component 5 will always supply lubricant in one direction to prevent backflow of lubricant and the generation of unwanted air bubbles in the lubricant.

[0039] 2 and 3, the pump component 5 provided at one end of the intermediate transmission shaft 21 has a cavity 54 for storing a lubricant inside the pump component 5. Furthermore, the pump component 5 has a plurality of internal passages for receiving the lubricant from the cavity 54 and supplying the lubricant to the hollow axial passage 211 of the intermediate transmission shaft 21, as well as for directly supplying the lubricant to external components disposed on the intermediate transmission shaft 21.

[0040] The pump component 5 further includes a pump shaft 53 coaxially mounted on the intermediate transmission shaft 21. A coupling element 28 is provided to fixedly connect the intermediate transmission shaft 21 and the pump shaft 53. This allows the pump shaft 53 to be rotationally and axially fixed to the transmission shaft 21. In one embodiment, the coupling element 28 can be a sleeve. The pump shaft 53 is driven by the transmission shaft through the coupling element 28. The pump component 5 is then driven to supply lubricant. The high pressure generated by the pump component 5 causes the lubricant in the cavity 54 to flow out through multiple passages within the pump component 5. In one embodiment, if the pump component 5 is not configured to supply lubricant in one direction, the coupling element 28 can be a one-way clutch that allows rotation in one direction and prevents force from being driven in the opposite direction. As a result, the pump shaft 53 is driven to rotate only in the forward direction by the coupling element 28, i.e., the one-way clutch, and lubricant flows only in one direction.

[0041] In the illustrated embodiment, the plurality of passages includes an axial passage 531 inside the pump shaft 53. The axial passage is in fluid communication with the hollow axial passage 211 of the intermediate transmission shaft 21. As shown in FIG. 3 , the plurality of passages further includes at least one lateral passage 51 extending radially from the cavity 54 to transport the lubricant stored in the cavity 54. The axial passage 531 is further in fluid communication with the at least one lateral passage 51. This allows the lubricant contained in the cavity 54 to be transported by the lateral passage 51 into the axial passage 531 and further into the hollow axial passage 211 of the intermediate transmission shaft 21. This allows lubrication of the bearings at the end of the intermediate shaft.

[0042] In one embodiment, the coupling part 28 comprises a connection 281 arranged on the radial surface between the axial passage 531 of the pump shaft 5 and the hollow axial passage 211 of the intermediate transmission shaft 21. The connection 281 is designed to prevent lubricant from returning or leaking out of the hollow axial passage 211 of the intermediate transmission shaft 21. This type of arrangement is also used to operate the pump part 5.

[0043] 2, the plurality of passages further includes at least one longitudinal passage 52 extending axially from the cavity 54 for supplying lubricant to components disposed on the intermediate transmission shaft. The at least one longitudinal passage 52 is in fluid communication with the circular gap 26 provided between the pump shaft 53 and the intermediate transmission shaft 21. This allows the lubricant contained in the cavity 54 to be supplied to components disposed on the intermediate transmission shaft 21 via the longitudinal passage 52 and the circular gap 26.

[0044] Furthermore, in the illustrated embodiment, the circular gap 26 is disposed laterally adjacent to a bearing 27 that supports the intermediate transmission shaft 21. Lubricant can flow from the longitudinal passage 52 through the circular gap 26 toward the bearing 27 for lubrication purposes.

[0045] As shown in Fig. 4, the intermediate transmission shaft 21 further includes at least one radial passage 212, 213, 214 distributed circumferentially. The radial passages 212, 213, 214 are in fluid communication with the hollow axial passage 211 to transport lubricant to components disposed on the intermediate transmission shaft 21. In this manner, lubricant can flow from the interior of the intermediate transmission shaft 21 to the seat of the drive gear 24, the driven gear 23, the actuator 8, the bearing 7, and other components for lubrication purposes. In the illustrated embodiment, the actuator 8, which is a solenoid, can be cooled by the lubricant flowing from the radial passages 212, 213, in particular, in the lubrication projection.

[0046] The above description uses examples to disclose embodiments of the present disclosure, including the best mode, and also enables any person skilled in the art to practice embodiments of the present disclosure, including making and using any devices or systems and performing any included 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 that are substantially different from the literal language of the claims.

Claims

1. an electric motor configured to provide a driving force, the electric motor including a rotor and a drive shaft driven by the rotor; a speed reducer configured to reduce speed and increase torque received from the drive shaft, the speed reducer including an intermediate transmission shaft having a hollow axial passage; a pump component configured to pump lubricant, mechanically integrated into and driven by the intermediate transmission shaft, the pump component comprising a plurality of passages for supplying lubricant to the hollow axial passage of the intermediate transmission shaft and to components disposed on the intermediate transmission shaft; Equipped with The plurality of passages include: at least one lateral passage for supplying lubricant to the hollow axial passage of the intermediate transmission shaft; at least one longitudinal passage for supplying lubricant to the components disposed on the intermediate transmission shaft; Equipped with the pump component further comprises a pump shaft coaxially mounted on the intermediate transmission shaft and configured to operate the pump component to supply lubricant; The plurality of passages further comprises an axial passage within the pump shaft, the axial passage fluidly communicating with the hollow axial passage of the intermediate transmission shaft.

2. The axial passage is further in fluid communication with at least one of the lateral passages. The drivetrain system of claim 1 .

3. the pump shaft is actuated by a coupling piece fixedly connected to the intermediate transmission shaft and the pump shaft; The drivetrain system of claim 1 .

4. The coupling part is a sleeve or a one-way clutch configured to always rotate in one direction. The drive train system of claim 3 .

5. the coupling part comprises a connection part that prevents lubricant from returning from the hollow axial passage of the intermediate transmission shaft or from leaking from the hollow axial passage of the intermediate transmission shaft. The drive train system of claim 3 .

6. At least one of the longitudinal passages is fluidly connected to a circular gap provided between the pump shaft and the intermediate transmission shaft, so that lubricant can be supplied to the parts arranged on the intermediate transmission shaft through the circular gap. The drivetrain system of claim 1 .

7. the circular gap is provided laterally adjacent to a bearing supporting the intermediate transmission shaft, so that lubricant can be supplied to the bearing through the circular gap. The drive train system of claim 6.

8. the intermediate transmission shaft further comprises at least one radial passage, the at least one radial passage being in fluid communication with the hollow axial passage so as to transport lubricant to the components disposed on the intermediate transmission shaft; The drivetrain system of claim 1 .

9. the pump component further comprises a cavity configured to store the lubricant supplied by the plurality of passages, at least one lateral passage extending radially from the cavity to transport the lubricant stored in the cavity, and at least one longitudinal passage extending axially from the cavity to transport the lubricant stored in the cavity. The drivetrain system of claim 1 .

10. The pump component is configured to supply lubricant in one direction when the pump component is rotationally driven. The drivetrain system of claim 1 .

11. The drive train system comprises: a differential configured to distribute reduced drive force to the driven wheels; a disengageable clutch provided on the intermediate transmission shaft, the disengageable clutch configured to provide a decoupling of the driving force between the electric motor and the differential; Furthermore, the pump component is configured to pump lubricant to provide active lubrication to the reducer, minimizing the level of lubricant entering the differential; The drivetrain system of claim 1 .

12. the drivetrain system further comprising an actuator coaxially disposed with the disconnectable clutch and configured to provide an engagement force and a disengagement force to the disconnectable clutch, the actuator being cooled by the lubricant from at least one radial passage in fluid communication with a hollow axial passage of the intermediate transmission shaft. The drivetrain system of claim 11.

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