Two-speed electric bridge drive system

Abstract

This invention provides a two-speed electric axle drive system, comprising a system housing, a motor (E), an input shaft (Si), a shift unit (U), a differential (D), and a planetary gear set (PG). The output torque of the motor (E) is transmitted to the input shaft (Si). The shift unit (U) is disposed on the input shaft (Si). When the shift unit (U) selects the first gear, the input shaft (Si) transmits torque to the first gear set; when the shift unit (U) selects the second gear, the input shaft (Si) transmits torque to the second gear set. The first and second gear sets are used to transmit torque to the sun gear of the planetary gear set (PG). The ring gear of the planetary gear set (PG) is non-rotatably connected to the system housing, and the planet carrier of the planetary gear set (PG) is non-rotatably connected to the housing of the differential (D). According to this invention, the two-speed electric axle drive system has simple and compact component structures, high system reliability, and minimal NVH impact.

Description

Technical Field

[0001] This invention relates to the field of motor vehicles, particularly to the field of vehicle transmissions, especially to electric axle drive systems in pure electric vehicles or hybrid vehicles, and more specifically to a two-speed electric axle drive system. Background Technology

[0002] For electric vehicles, including pure electric vehicles and hybrid (hybrid) vehicles, their electric drive methods include two types: central motor drive and in-wheel motor drive. A common arrangement of the central motor drive system is also known as the eAxle drive system.

[0003] Figures 1 to 3 A two-speed electric bridge drive system is shown, which includes a motor E, a differential D, a planetary gear set PG, a synchronizer 10, a motor shaft Se, an input shaft Si, a gear shaft Sp, an intermediate shaft Sm, and two gear pairs.

[0004] The motor E and the transmission are separated. The motor shaft Se is connected to the transmission input shaft Si via a spline. The input shaft Si is partially nested with the gear shaft Sp, which has the first gear pair drive gear 21. The motor shaft Se, the sun gear of the planetary gear set PG, the input shaft Si, and the gear shaft Sp are coaxially arranged. The motor shaft Se is supported by the motor housing, the gear shaft Sp is supported by the transmission housing, and one end of the input shaft Si is supported by the transmission housing, while the other end is supported by the nested gear shaft Sp. The intermediate shaft Sm, which has the second gear pair drive gear 31, is supported by the transmission housing. The intermediate shaft Sm also has the first gear pair driven gear 22 mounted on it. The second gear pair driven gear 32 is mounted on the differential D housing.

[0005] The system speed gear is changed via a synchronizer 10 with a special structure. The hub 12 of the synchronizer 10 is connected to the gear shaft Sp via a spline, and the sliding sleeve 11 is supported by the input shaft Si via a synchronizing ring and also by the gear shaft Sp via the hub 12. A gear ring 13, which engages with the sliding sleeve 11 in the first gear position, is welded to the planet carrier of the planetary gear set PG and is supported by the input shaft Si; another gear ring 14, which engages with the sliding sleeve 11 in the second gear position, is connected to the input shaft Si via a spline.

[0006] Reference Figure 2 When the sliding sleeve 11 engages with the engagement gear ring 13, the system is in the first gear position. The power from the motor E is input from the sun gear of the planetary gear set PG, output from the planet carrier, and then transmitted sequentially through the engagement gear ring 13, sliding sleeve 11, gear hub 12, gear shaft Sp, first gear pair driving gear 21, first gear pair driven gear 22, intermediate shaft Sm, second gear pair driving gear 31, second gear pair driven gear 32 to the differential D.

[0007] Reference Figure 3 When the sliding sleeve 11 engages with the engagement gear ring 14, the system is in the second gear position. The power of the input shaft Si is transmitted to the engagement gear ring 14, and then sequentially transmitted through the sliding sleeve 11, the gear hub 12, the gear shaft Sp, the first gear pair drive wheel 21, the first gear pair driven wheel 22, the intermediate shaft Sm, the second gear pair drive wheel 31, the second gear pair driven wheel 32 to the differential D.

[0008] The above system has at least the following problems:

[0009] The motor shaft Se, input shaft Si, and gear shaft Sp, which are coaxially arranged, are all separately configured. In particular, the input shaft Si and gear shaft Sp need to be able to rotate relative to each other, and the gear shaft Sp needs to provide support for the input shaft Si, while the input shaft Si needs to provide support for the planetary carrier. Not only does the system have a large number of rotating shafts, but the individual support structures for each rotating component are also complex, with a large number of bearings, resulting in high system cost and low reliability.

[0010] As the first-stage reduction device, the planetary gear set PG has a high rotational speed, which is not conducive to the NVH control of the system.

[0011] The high horizontal position of the sun gear axis of the planetary gear set PG increases the difficulty of lubrication.

[0012] Synchronizer 10 has a special and complex structure, high manufacturing cost and low reliability. Moreover, synchronizer 10 occupies a large space in the system axis, which is not conducive to the design requirements of small axial size of the system. Summary of the Invention

[0013] The purpose of this invention is to overcome or at least mitigate the shortcomings of the prior art and provide a simple and compact two-speed electric bridge drive system.

[0014] This invention provides a two-speed electric axle drive system, comprising a system housing, a motor, an input shaft, a shift unit, a differential, and a planetary gear set, wherein...

[0015] The output torque of the motor is transmitted to the input shaft.

[0016] The shifting unit is mounted on the input shaft. When the shifting unit selects the first gear, the input shaft transmits torque to the first gear set; when the shifting unit selects the second gear, the input shaft transmits torque to the second gear set.

[0017] The first gear set and the second gear set are used to transmit torque to the sun gear of the planetary gear set. The ring gear of the planetary gear set is connected to the system housing in a non-rotatable manner, and the planet carrier of the planetary gear set is connected to the differential housing in a non-rotatable manner.

[0018] In at least one embodiment, the system further includes an intermediate shaft, a first gear, a second gear, a third gear, a fourth gear, and a fifth gear.

[0019] The first gear, the second gear, and the shifting unit are disposed on the input shaft. When the shifting unit selects the first gear, the second gear is connected to the input shaft in a way that prevents relative rotation; when the shifting unit selects the second gear, the first gear is connected to the input shaft in a way that prevents relative rotation.

[0020] Neither the fourth gear nor the third gear can be rotatably connected to the intermediate shaft.

[0021] The sun gear and the fifth gear are connected in a way that prevents them from rotating relative to each other.

[0022] The fourth gear meshes with the second gear, the third gear meshes with the fifth gear, and the first gear meshes with the fifth gear.

[0023] In at least one embodiment, the shifting unit includes a shifting selection component and a first gear engagement member and a second gear engagement member disposed on both axial sides of the shifting selection component.

[0024] The shift selection component is at least partially connected to the input shaft in a way that prevents relative rotation.

[0025] The first gear engagement member and the second gear are connected in a way that prevents relative rotation, and the second gear engagement member and the first gear are also connected in a way that prevents relative rotation.

[0026] Both the first gear and the second gear are rotatably mounted on the input shaft relative to it.

[0027] When the shift selection component is engaged with the first gear engagement member, the shift selection component and the first gear engagement member are connected in a way that prevents relative rotation; when the shift selection component is engaged with the second gear engagement member, the shift selection component and the second gear engagement member are connected in a way that prevents relative rotation.

[0028] In at least one embodiment, the shifting unit is a synchronizer, and the shifting selection component includes a synchronizer hub, a sliding sleeve, and two synchronizing rings, wherein the first gear engagement member and the second gear engagement member are engagement gear rings for engaging with the sliding sleeve.

[0029] In at least one embodiment, the shifting unit is a clutch, the shifting selection component is the driving part of the clutch, and the first gear engagement member and the second gear engagement member are the driven plates of the clutch.

[0030] In at least one embodiment, the rotation axes of the input shaft, the intermediate shaft, and the output half-shaft of the differential are parallel and offset radially from the input shaft.

[0031] In at least one embodiment, the planetary gear set is located further away from the motor than the third, fourth, and fifth gears in the axial direction of the input shaft.

[0032] In at least one embodiment, the ring gear of the planetary gear set is located between the fourth gear and the fifth gear in the axial direction of the input shaft.

[0033] In at least one embodiment, the electric bridge drive system further includes a gear ring fixing plate, which is detachably mounted to the system housing relative to the system housing, and is used to fix the gear ring of the planetary gear set.

[0034] In at least one embodiment, the gear ring fixing plate includes an opening for receiving the gear ring, the opening having internal teeth, the gear ring having external teeth, the internal teeth engaging with the external teeth.

[0035] The two-speed electric bridge drive system according to the present invention has simple and compact structure of each component, high system reliability, and low NVH impact. Attached Figure Description

[0036] Figures 1 to 3 This is a schematic diagram of a possible two-speed electric bridge drive system.

[0037] Figure 4 This is a schematic diagram of a two-speed electric bridge drive system according to the first embodiment of the present invention.

[0038] Figure 5 yes Figure 4 The diagram shows the power transmission path of the electric bridge drive system in the first gear.

[0039] Figure 6 yes Figure 4 The diagram shows the power transmission path of the electric axle drive system in the second gear.

[0040] Figure 7 This is a schematic diagram of a two-speed electric bridge drive system according to a second embodiment of the present invention.

[0041] Explanation of reference numerals in the attached figures

[0042] 10 Synchronizer; 11 Sliding sleeve; 12 Gear hub; 13, 14 Engaging gear ring;

[0043] E motor; PG planetary gear set; D differential;

[0044] Se motor shaft; Si input shaft; Sp gear shaft; Sm intermediate shaft;

[0045] 21 First gear to driving gear; 22 First gear to driven gear; 31 Second gear to driving gear; 32 Second gear to driven gear;

[0046] U-shift unit; U1 first gear engagement component; U2 second gear engagement component;

[0047] G1 First gear; G2 Second gear; G3 Third gear; G4 Fourth gear; G5 Fifth gear;

[0048] R is radial; A is axial. Detailed Implementation

[0049] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement the present invention, and are not intended to exhaustively describe all possible ways of the invention, nor to limit the scope of the invention.

[0050] Unless otherwise specified, refer to Figure 4 and Figure 7 A represents the axial direction of the electric bridge drive system, which is consistent with the axial direction of the motor E in the electric bridge drive system; R represents the radial direction of the electric bridge drive system, which is consistent with the radial direction of the motor E in the electric bridge drive system.

[0051] (First Implementation)

[0052] First refer to Figures 4 to 6 The structure and operation of the electric bridge drive system according to the first embodiment of the present invention are described.

[0053] The electric bridge drive system according to the present invention includes a motor E, an input shaft Si, an intermediate shaft Sm, a shifting unit U, a first gear G1, a second gear G2, a third gear G3, a fourth gear G4, a fifth gear G5, a differential D, and a planetary gear set PG.

[0054] The first gear G1, the second gear G2, and the shift unit U are located on the input shaft Si. Only when the shift unit U selectively engages either the first gear G1 or the second gear G2 can either gear G1 or G2 rotate with the input shaft Si. The third gear G3 and the fourth gear G4 are located on the intermediate shaft Sm, and both gears rotate with the intermediate shaft Sm. The fifth gear G5 and the sun gear of the planetary gear set PG are torsionally connected to each other and are located on one output half-shaft of the differential D. Both the fifth gear G5 and the planetary gear set PG rotate independently of this output half-shaft. The planet carrier of the planetary gear set PG is also torsionally connected to the housing of the differential D.

[0055] The input shaft Si, intermediate shaft Sm, and output half-shaft of differential D are parallel and offset in the radial direction R.

[0056] The fourth gear G4 is always meshed with the second gear G2, the third gear G3 is always meshed with the fifth gear G5, and the first gear G1 is always meshed with the fifth gear G5. Preferably, the second gear G2 has fewer teeth than the fourth gear G4, and the first gear G1 and the third gear G3 both have fewer teeth than the fifth gear G5.

[0057] The torque of motor E is transmitted to the input shaft Si. After the shift unit U selects the appropriate first or second gear set for transmitting torque, the torque is transmitted through the first or second gear set to the sun gear of the planetary gear set PG, and finally to the differential D. The second gear G2, fourth gear G4, third gear G3, and fifth gear G5 constitute the first gear set, while the first gear G1 and fifth gear G5 constitute the second gear set. The connection relationships and power transmission paths of different gears described below will make the composition of these two gear sets easier to understand.

[0058] The shift unit U includes a shift selection assembly and a first gear engagement member U1 and a second gear engagement member U2 located on either side of the shift selection assembly along the axial direction A. The shift selection assembly is at least partially and torsionalally (non-rotatably) connected to the input shaft Si, and is at least partially movable along the axial direction A relative to the first gear engagement member U1 and the second gear engagement member U2, thereby selectively engaging with either the first gear engagement member U1 or the second gear engagement member U2 to transmit torque. The first gear engagement member U1 is torsionalally connected to the second gear G2, or the two are integrally formed; the second gear engagement member U2 is torsionalally connected to the first gear G1, or the two are integrally formed. Both the first gear G1 and the second gear G2 are rotatably mounted on the input shaft Si relative to the input shaft Si via bearings.

[0059] When the shift selection component engages with the first gear engagement member U1, both the first gear engagement member U1 and the second gear G2 are connected to the input shaft Si in a torsion-resistant manner; when the shift selection component engages with the second gear engagement member U2, both the second gear engagement member U2 and the first gear G1 are connected to the input shaft Si in a torsion-resistant manner.

[0060] The shift unit U can be a conventional synchronizer, in which the synchronizer's hub, sleeve, and two synchronizer rings form the shift selection component. The hub is torsionally connected to the input shaft Si, the sleeve is torsionally connected to the hub, and the sleeve can slide relative to the hub in the axial direction A. The first gear engagement member U1 and the second gear engagement member U2 are both engagement gear rings.

[0061] The shift unit U can also be a plate clutch, for example, in which case the driving part of the clutch is the shift selection component, and the two driven plates of the clutch are the first gear engagement member U1 and the second gear engagement member U2, respectively. The driving part of the clutch can, for example, be at least partially movable in the axial direction A under hydraulic drive.

[0062] Both the third gear G3 and the fourth gear G4 are torsionally connected to the intermediate shaft Sm.

[0063] The fifth gear G5 is torsionally connected to the sun gear of the planetary gear set PG, or the two are integrated into one unit.

[0064] The planet carrier of the planetary gear set PG is torsionally connected to the housing of the differential D, or the two are integrated into one unit.

[0065] The ring gear of the planetary gear set PG is fixed to the housing of the transmission (the motor E and the transmission can also share a housing, in which case the entire housing is also referred to as the system housing).

[0066] In this embodiment, from the direction of the motor E pointing to the transmission, the input shaft Si is arranged with the second gear G2, the shift unit U and the first gear G1 in sequence, the intermediate shaft Sm is arranged with the fourth gear G4 and the third gear G3 in sequence, and the output half shaft of the differential D is arranged with the fifth gear G5 and the planetary gear set PG in sequence.

[0067] Along axis A, the ring gear of the planetary gear set PG is farther from the motor E than any of the first gear G1, second gear G2, third gear G3, fourth gear G4, and fifth gear G5. This facilitates the installation of system components and simplifies the design of the transmission housing. For example, the planetary gear set PG can be installed first within the complete transmission housing, followed by the installation of the aforementioned five gears.

[0068] Figure 5 and Figure 6 The power transmission path of the electric bridge drive system according to the first embodiment of the present invention is shown in two gear positions.

[0069] Reference Figure 5 In the first gear position, the shift selection component engages with the first gear engagement member U1. The power transmission path is as follows: motor E, input shaft Si, shift selection component of shift unit U, first gear engagement member U1, second gear G2, fourth gear G4, intermediate shaft Sm, third gear G3, fifth gear G5, sun gear of planetary gear set PG, planet gears, planet carrier to differential D.

[0070] Let the number of teeth of the first gear G1, the second gear G2, the third gear G3, the fourth gear G4, the fifth gear G5, the sun gear, and the ring gear be Z1, Z2, Z3, Z4, Z5, Zs, and Zr, respectively. Then the transmission ratio of the system in the first gear is Z4 / Z2×Z5 / Z3×(1+Zr / Zs).

[0071] Reference Figure 6 In the second gear position, the shift selection component engages with the second gear engagement member U2. The power transmission path is as follows: motor E, input shaft Si, shift selection component of shift unit U, second gear engagement member U2, first gear G1, fifth gear G5, sun gear of planetary gear set PG, planet gears, planet carrier to differential D. The transmission ratio of the system in the second gear position is Z5 / Z1×(1+Zr / Zs).

[0072] (Second Implementation)

[0073] Next, refer to Figure 7 This invention introduces a two-speed electric bridge drive system according to a second embodiment of the present invention. The second embodiment is a variation of the first embodiment. The main difference between the second and first embodiments lies in the change of the positions of the planetary gear set PG and the differential D in the axial direction A, as well as the adaptive changes in the positions of other components in the axial direction A. This change can lead to a reduction in the axial dimension of the system.

[0074] In this embodiment, from the direction of the motor E pointing to the transmission, the input shaft Si is arranged with the first gear G1, the shift unit U and the second gear G2 in sequence, the intermediate shaft Sm is arranged with the third gear G3 and the fourth gear G4 in sequence, and the output half shaft of the differential D is arranged with the fifth gear G5 and the planetary gear set PG in sequence.

[0075] In particular, the planetary gear set PG and the differential D are located at least partially between the fifth gear G5 and the fourth gear G4 on axis A, thereby making full use of the space on axis A inside the transmission.

[0076] In this embodiment, if the ring gear of the planetary gear set PG is directly fixed to the transmission housing, the fourth gear G4 may interfere with the transmission housing at the ring gear fixing structure during installation. To simplify the structure of the transmission housing and facilitate the installation of the planetary gear set PG and other gears, the electric axle drive system according to this embodiment also includes a ring gear fixing plate (not shown in the figure) detachably connected to the transmission housing.

[0077] For example, the gear ring retainer plate is bolted to the transmission housing. The gear ring retainer plate has an opening to accommodate the gear ring of the planetary gear set PG, and the opening has internal teeth that mate with the external teeth of the gear ring, thus ensuring that the gear ring and the gear ring retainer plate are connected without relative rotation. During the installation of the components, the intermediate shaft Sm and the fourth gear G4 can be installed first, followed by the gear ring retainer plate and the planetary gear set PG.

[0078] This invention has at least one of the following advantages:

[0079] (i) The components of the present invention have simple structures. In particular, the shift unit U can use a conventional synchronizer, which makes the system structure compact, highly reliable and low cost.

[0080] (ii) The planetary gear set PG is connected to the differential D. Compared with the method of setting the planetary gear set PG on the input shaft Si, on the one hand, the rotational speed of each rotating part of the planetary gear set PG is lower, which is conducive to reducing the NVH of the system; on the other hand, the horizontal position of the planetary gear set PG is lowered, which is beneficial to the lubrication control of the planetary gear set PG.

[0081] Of course, the present invention is not limited to the above embodiments. Those skilled in the art can make various modifications to the above embodiments of the present invention under the guidance of the present invention, without departing from the scope of the present invention.

Claims

1. A two-speed electric axle drive system, comprising a system housing, a motor (E), an input shaft (Si), a shift unit (U), a differential (D), and a planetary gear set (PG), wherein, The output torque of the motor (E) is transmitted to the input shaft (Si). The shifting unit (U) is disposed on the input shaft (Si). When the shifting unit (U) selects the first gear, the input shaft (Si) transmits torque to the first gear set; when the shifting unit (U) selects the second gear, the input shaft (Si) transmits torque to the second gear set. The first and second gear sets are used to transmit torque to the sun gear of the planetary gear set (PG). The ring gear of the planetary gear set (PG) is connected to the system housing in a non-rotatable manner, and the planet carrier of the planetary gear set (PG) is connected to the differential (D) housing in a non-rotatable manner. The system also includes an intermediate shaft (Sm), a first gear (G1), a second gear (G2), a third gear (G3), a fourth gear (G4), and a fifth gear (G5). The first gear (G1), the second gear (G2), and the shift unit (U) are disposed on the input shaft (Si). When the shift unit (U) selects the first gear, the second gear (G2) is connected to the input shaft (Si) in a way that prevents relative rotation; when the shift unit (U) selects the second gear, the first gear (G1) is connected to the input shaft (Si) in a way that prevents relative rotation. The fourth gear (G4) and the third gear (G3) are connected to the intermediate shaft (Sm) in a manner that prevents them from rotating relative to each other. The sun gear and the fifth gear (G5) are connected in a manner that prevents them from rotating relative to each other. The fourth gear (G4) meshes with the second gear (G2), the third gear (G3) meshes with the fifth gear (G5), and the first gear (G1) meshes with the fifth gear (G5).

2. The bridge drive system according to claim 1, characterized in that, The shift unit (U) includes a shift selection component and a first gear engagement member (U1) and a second gear engagement member (U2) disposed on both axial sides of the shift selection component. The shift selection component is at least partially connected to the input shaft (Si) in a way that prevents relative rotation. The first gear engagement member (U1) and the second gear (G2) are connected in a way that prevents them from rotating relative to each other. Both the first gear (G1) and the second gear (G2) are rotatably mounted on the input shaft (Si) relative to the input shaft (Si). When the shift selection component is engaged with the first gear engagement member (U1), the shift selection component and the first gear engagement member (U1) are connected in a way that prevents relative rotation; when the shift selection component is engaged with the second gear engagement member (U2), the shift selection component and the second gear engagement member (U2) are connected in a way that prevents relative rotation.

3. The bridge drive system according to claim 2, characterized in that, The shift unit (U) is a synchronizer, and the shift selection component includes a synchronizer hub, a sliding sleeve, and two synchronizer rings. The first gear engagement member (U1) and the second gear engagement member (U2) are engagement gear rings for engaging with the sliding sleeve.

4. The bridge drive system according to claim 2, characterized in that, The shift unit (U) is a clutch, the shift selection component is the active part of the clutch, and the first gear engagement member (U1) and the second gear engagement member (U2) are the driven plates of the clutch.

5. The electric bridge drive system according to any one of claims 1 to 4, characterized in that, The rotation axes of the input shaft (Si), the intermediate shaft (Sm), and the output half-shaft of the differential (D) are parallel and offset in the radial direction (R) of the input shaft (Si).

6. The bridge drive system according to claim 5, characterized in that, Along the axial direction (A) of the input shaft (Si), the planetary gear set (PG) is farther away from the motor (E) than the third gear (G3), the fourth gear (G4), and the fifth gear (G5).

7. The bridge drive system according to claim 5, characterized in that, Along the axial direction (A) of the input shaft (Si), the ring gear of the planetary gear set (PG) is located between the fourth gear (G4) and the fifth gear (G5).

8. The bridge drive system according to claim 7, characterized in that, The electric bridge drive system also includes a gear ring fixing plate, which is detachably mounted to the system housing relative to the system housing, and is used to fix the gear ring of the planetary gear set (PG).

9. The bridge drive system according to claim 8, characterized in that, The gear ring fixing plate includes an opening for receiving the gear ring, the opening having internal teeth, the gear ring having external teeth, and the internal teeth engaging with the external teeth.

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