Gear assemblies used in electric drive transmissions

Abstract

A gear assembly for use with an electric motor includes: a drive gear connected to the output shaft of the electric motor and rotatable about a drive shaft; a planetary gear assembly including a sun gear, a planetary gear assembly, an input stage, and an output stage, the planetary gear assembly being rotatably supported on a planetary carrier about a shaft and meshing with the sun gear and optionally with a ring gear, the input stage being connected to the drive gear, and the output stage being connected to a drive member for its rotation about the drive shaft; a clutch assembly that slidably connects the ring gear to the planetary carrier or the drive member; and a brake assembly that securely engages a portion of the planetary gear assembly with a locking portion of the gear assembly. In the low-speed range of the gear assembly, the clutch and brake assembly are operated such that torque is transmitted from the drive gear to the planetary gear assembly and through its output stage to the drive member. In the high-speed range, the clutch and brake assembly are operated such that the planetary carrier is securely connected to the drive member and rotates about the drive shaft such that torque is transmitted from the drive gear to the drive member via the planetary carrier.

Description

Technical Field

[0001] This invention relates to a gear assembly used in an electric drive transmission. The invention also relates to an electric vehicle including such a gear assembly. Background Technology

[0002] Electric drive transmissions in electric vehicles are typically made as single-speed transmissions, with a gear ratio that is a trade-off between the maximum torque during start-up and acceleration and the maximum permissible speed of the electric motor. Highly efficient drivetrains are achieved using a single-stage gearbox that operates across both low and high speed ranges.

[0003] This provides a 2-speed electric drivetrain that results in further efficiency gains and a longer range. Using a 2-speed transmission allows for a reduction in the size of the electric motor.

[0004] In known 2-speed electric drives, planetary gear sets are used in a two-speed transaxle with two clutches: one clutch connected to the sun gear and the other to the ring gear. For operation in the low-speed range, the first clutch is deactivated to transmit power via the ring gear through the planetary gear set. For operation in the high-speed range, the first clutch is engaged and the second clutch is deactivated to transmit power via the sun gear, thus allowing the ring gear to rotate freely without transmitting any torque.

[0005] This known system leads to losses in the planetary gear stage.

[0006] One object of the present invention is to provide a drive system for an electric motor that has a compact and lightweight structure and improved efficiency. Summary of the Invention

[0007] Therefore, the gear assembly according to the invention for use with an electric motor includes:

[0008] - A drive gear adapted to be connected to the output shaft of an electric motor, the drive gear being rotatable about a transmission shaft.

[0009] - A planetary gear assembly comprising at least one sun gear, two or more planetary gear members, an input stage, and an output stage, wherein the two or more planetary gear members are rotatably supported on a planet carrier about their respective planetary gear shafts and mesh with the sun gear and optionally with a ring gear; the input stage is connected to the drive gear; and the output stage is adapted to be connected to a drive member for rotation of the drive member about the drive shaft.

[0010] - A clutch component adapted to slidably connect the planetary carrier or ring gear to the drive component, and

[0011] - A braking component adapted to securely engage a portion of the planetary gear assembly with a locking portion of the gear assembly.

[0012] In the low-speed range, the clutch component and the brake component are operated such that torque is transmitted from the drive gear to the planetary gear assembly, and then through the output stage of the planetary gear assembly to the drive component.

[0013] At high speeds, the clutch assembly and the brake assembly are operated such that the planetary carrier rotates about the drive shaft and torque is transmitted from the drive gear to the drive assembly via the planetary carrier.

[0014] In the low-speed range, the planetary gear stage according to the invention transmits torque from the drive gear to a rotating component that may include a differential housing. A high gear ratio is achieved at reduced speeds and higher torque as power flows through the first stage of the drive gear and through the second planetary gear stage.

[0015] In the high-speed range, the clutch and brake components deactivate the planetary phase and rotatably connect it to the drive component, such that torque is transmitted from the motor to the rotating component only through a single stage formed by the drive gear, while the planetary phase rotates together with the drive component about the drive shaft, which may be a wheel axle.

[0016] In the high-speed range, single-stage gear reduction results in reduced losses and higher efficiency.

[0017] The drive gear may include a cylindrical gear rotatable about a drive shaft. The drive shaft may include a wheel axle, and the drive component may include a differential housing in an electric vehicle.

[0018] Planetary gear stages can be single or compound, depending on the required gear ratio.

[0019] As used in this article, “locked portion” is intended to refer to the part of a gear assembly that is stationary relative to the rotatable gear, such as the gear housing.

[0020] Gear 1 can have a gear ratio in the range of 8 to 12 and will be used only for starting and acceleration. Power flow first passes through the cylindrical gear stage and then through the planetary gear stage. Gear 2 can be considered as a single-stage reducer with a gear ratio of, for example, 4.5, wherein the planetary gear set is deactivated by locking the ring gear to the differential housing, and torque is transmitted only through the cylindrical gear of stage 1.

[0021] In one embodiment of the gear assembly according to the invention, the planetary gear assembly includes an outer ring, the planetary gear member meshing with the outer ring and with a sun gear, the outer ring being connectable to the drive member via a clutch member, wherein the locking portion engages the outer ring.

[0022] Embodiments using a single planetary gear can result in a gear ratio of 2.5:1 and even higher.

[0023] In such embodiments, i.e. for planetary gear stages, a gear ratio of less than 2.5:1 is required. In embodiments where this would result in the sun gear being almost the same size as the ring and the diameter of the planetary gears being reduced in a single planetary gear stage, a compound planetary gear set is used.

[0024] One embodiment of the gear assembly according to the invention includes a compound planetary gear.

[0025] - The planetary gear components are supported on the planet carrier at spaced intervals along the planet carrier shaft so that they can rotate together about the planet carrier shaft.

[0026] - The drive gear engages with the planet carrier for the planet carrier to rotate about the drive shaft.

[0027] - The first sun gear can rotate around the drive shaft and mesh with the first planetary gear assembly.

[0028] - The second sun gear can rotate around the drive shaft, is fixedly connected to the drive component, and meshes with the second planetary gear component.

[0029] - A braking component is connected to a first sun gear and a non-rotating locking portion to prevent the first sun gear from rotating about the drive shaft when the braking component is engaged, and

[0030] - The clutch assembly is arranged to connect the planetary carrier to the drive assembly.

[0031] Another embodiment of the gear assembly according to the invention includes a compound planetary gear, wherein

[0032] - The planetary gear components are supported on the planet carrier at spaced intervals along the planet carrier shaft so that they can rotate together about the planet carrier shaft.

[0033] - The drive gear engages with multiple sun gears, causing the multiple sun gears to rotate around the drive shaft.

[0034] - The first sun gear can rotate around the drive shaft and mesh with the first planetary gear assembly.

[0035] - The second sun gear can rotate around the drive shaft, is fixedly connected to the drive component, and meshes with the second planetary gear component.

[0036] - A braking component is connected to the planetary carrier and a non-rotating locking portion to prevent the planetary carrier from rotating about the drive shaft when the braking component is engaged. Attached Figure Description

[0037] Some embodiments of the gear assembly according to the present invention will be described in detail with reference to the accompanying drawings by way of non-limiting example. In the drawings:

[0038] Figure 1 A cross-sectional view of a gear assembly according to the present invention is shown, the gear assembly comprising a single planetary gear with an outer ring.

[0039] Figure 2 A schematic diagram of one embodiment of a gear assembly including a compound planetary gear is shown.

[0040] Figure 3 Displayed when in first gear Figure 2 The power flow of the gear assembly,

[0041] Figure 4 It shows the passage in second gear. Figure 2 The power flow of the gear assembly,

[0042] Figure 5 A schematic diagram of a second embodiment of a gear assembly including a compound planetary gear is shown, and

[0043] Figure 6 Showing Figure 5 Cross-sectional view of the gear assembly. Detailed Implementation

[0044] Figure 1 Gear assembly 1 is shown, which is connected to a motor 2 having an output shaft 3 that is rotatable about a shaft 4. Motor 2 drives output shafts 5 and 6, each of which is connected to a wheel (not shown) via a two-stage gear assembly 8. Output shafts 5 and 6 are rotatable about a drive shaft / axis 7, which is parallel to the axis of output shaft 3 and spaced apart by a distance, for example, 14 cm.

[0045] The two-stage gear assembly 8 includes a cylindrical gear 9 and a planetary gear assembly 10. The planetary gear assembly 10 includes a sun gear 11; a planet carrier 12; planet gears 13 and 14; and an external ring gear 15, which meshes with planet gears 13 and 14. Planet gears 13 and 14 are supported on the planet carrier 12 to rotate about their respective planetary gear shafts 18 and 19. The planet carrier 12 is part of the housing 20 of the differential 21. The ring gear 15 is connected to the planet carrier 12 and to the housing 20 of the differential 21 via a wet clutch 23. A braking member 24, such as a mechanical diode, is capable of selectively locking the ring gear 15 to a non-rotating component, such as to the housing of the gear assembly 8.

[0046] In the low speed range or first gear, the brake member 24 is engaged and the clutch 23 is released, thereby engaging the planetary gears. The ring gear 15 is fixed to the housing and cannot rotate about the shaft 7. The spur gear 9 drives the sun gear 11, and power is transmitted to the housing 20 via the planet carrier 12 through planetary gears 13 and 14 rotating about their respective shafts 18 and 19 on the planet carrier 12. Power is transmitted from the rotating differential housing 20 to the differential 21 and the two output shafts 5 and 6. If the gear ratio of the spur gear is approximately 4.5:1 and the minimum gear ratio of the single-stage planetary gear is 2.5:1, then the total gear ratio in the first gear is 4.5 * 2.5 = 11.25.

[0047] In the high-speed range or in second gear, the brake member 24 is released and the clutch 23 is engaged, thereby deactivating the entire planetary gear assembly 10 and locking it to the differential housing 20. Second gear can be considered as a single-stage reduction gear with a ratio of, for example, 4.5:1. Compared to a two-stage gear transmission in the low-speed range, this creates a highly efficient transmission designed to operate in second gear as much as possible during the driving cycle.

[0048] Figure 2 An embodiment of a gear assembly 30 with a compound planetary gear stage 31 is schematically shown, which is adapted to obtain a gear ratio of less than 11 in the first gear. The rotor shaft 33 and pinion 34 of the electric motor 32 are connected to a gear wheel 36, which is supported on a shaft 41 parallel to the rotor shaft 33. The pinion 34 and gear 36 form the first gear reduction stage of the gear assembly 30.

[0049] The shaft of gear assembly 30 is essentially designed for the planet carrier 35 of planetary gear set 31, which is the second gear reduction stage of the gearbox. Planetary gear stage 31 includes a first sun gear 37; planetary gears 38 and 39; and a second sun gear 40.

[0050] The second sun gear 40 forms the output stage of the planetary gear 31. It permanently meshes with a plurality of planetary gears 39 and is fixedly attached to the differential housing 50. The differential housing 50 contains a differential 51, which transmits the rotation of the housing 50 to the axles 52, 53 of the wheels 54, 55.

[0051] The multidisc wet clutch 48 connects and disconnects the planetary carrier 35 from the differential housing 50.

[0052] The first sun gear 37 forms the input to the planetary gear stage 31 and permanently meshes with a plurality of planetary gears 38. The first sun gear 37 is also connected to a multi-disc brake 42, which is attached to the housing 43 of the gear assembly in a non-rotational manner. When the multi-disc brake 42 is locked, the sun gear 37 remains stationary. When the multi-disc brake 42 is released, the sun gear 37 rotates freely on its support bearings 44, 45.

[0053] Each planetary gear 38, 39 forms a common compound gear unit, which is supported on the planet carrier 35 via bearings 46, 47.

[0054] In gear 1 (high torque, low speed), power flows through two gear reduction stages 34, 36, and 31. Brake 42 is locked and clutch 48 is released. Power is transmitted from input pinion 34 to gear 36; to first sun gear 37; to planetary gear 38; to planetary gear 39; to second sun gear 40; to differential housing 50; to differential pin and gear 51; to drive shafts 52 and 53; and to wheels 54 and 55.

[0055] exist Figure 3 In the first gear, the power flow through the gear reduction stage is indicated by the arrow.

[0056] like Figure 2 As shown, in gear 2 (low torque, high speed), power flows only through gear reduction stage 1 formed by pinion 34 and gear 36. Brake 42 is released and clutch 48 is locked, thus connecting planetary carrier 35 to differential housing 50. Planetary gear stage 31 rotates together with differential housing 50 as a lump mass. Power is transmitted from input pinion 34 to gear 36; to planetary carrier 35; to clutch 48; to differential housing 50; to differential pin and gear 51; to drive shafts 52, 53; and to wheels 54, 55.

[0057] exist Figure 4 In the second gear, the power flow through the gear reduction stage is indicated by the arrow.

[0058] Figure 5 Another embodiment of a gear assembly 30 having a compound planetary gear stage 31 is schematically shown. The rotor shaft 33 of the electric motor 32 and a pinion 34 are connected to a gear 36, which is supported on a shaft 41 parallel to the rotor shaft 33. The pinion 34 and the gear 36 form the first gear reduction stage of the gear assembly 30.

[0059] The second gear reduction stage 31, or gear assembly 31, of the gearbox is planetary. The planetary gear set consists of a first sun gear 37, planetary gears 38 and 39, and a second sun gear 40.

[0060] The first sun gear 37 is securely attached to and concentrically mounted with the first-stage gear 36. The sun gear 37 and gear 36 form a unit supported on the differential housing 50 by bearings 44 and 45. The first sun gear 37 permanently meshes with a plurality of planetary gears 38.

[0061] Planetary gears 38 and 39 form a common compound gear unit, which is supported on planet carrier 35 via bearings 46 and 47.

[0062] The second sun gear 40 forms the output of the planetary gear set 31 and is fixedly attached to the differential housing 50. The second sun gear 40 is permanently meshed with a plurality of planetary gears 39.

[0063] The multi-plate wet clutch 48 connects and disconnects the planetary carrier 35 from the differential housing 50 in a sliding manner.

[0064] The multi-disc brake 42 is operated to connect and disconnect the planet carrier 35 from the gearbox housing 43 (locking and releasing the planet carrier).

[0065] In gear 1 (high torque, low speed), power flows through two gear reduction stages 34, 36, and 31. The brake 42 is locked and the clutch 48 is released. Power is transmitted from the input pinion 34 to gear 36; to the first sun gear 37; to planetary gear 38; to planetary gear 39; to the second sun gear 40; to the differential housing 50; to the differential pin and gear 51; and to the drive shafts 52 and 53 and the wheels 54 and 55.

[0066] like Figure 5As shown, in gear 2 (low torque, high speed), power flows only through gear reduction stage 1 formed by pinion 34 and gear 36. Brake 42 is released and clutch 48 is locked. Clutch 48 connects planetary carrier 35 to differential housing 50, and the entire planetary gear stage 31 rotates as a block mass together with differential housing 50. Power flows from input pinion 34 to gear 36; to the first sun gear 37; to planetary gear 38; to planetary carrier 35; to clutch 48; to differential housing 50; to differential pin and gear 51; and to drive shafts 52, 53 and wheels 54, 55.

[0067] exist Figure 6 In, it is shown Figure 5 Cross-sectional view of the gear assembly.

Claims

1. A gear assembly (1, 30) for use with an electric motor (2, 32), comprising: - Drive gears (9, 36), adapted to be connected to the output shafts (3, 33) of an electric motor (2, 32), said drive gears (9, 36) being rotatable about transmission shafts (7, 52, 53). - A planetary gear assembly (10, 31) comprising a sun gear (11, 37, 40), two or more planetary gear members (13, 14, 38, 39), an input stage, and an output stage, wherein the two or more planetary gear members are rotatably supported on a planet carrier (12, 35) about their respective planetary gear shafts (18, 19) and mesh with one or more of the sun gears (11, 37, 40) and the ring gear (15), the input stage is connected to the drive gear (9, 36), and the output stage is adapted to be connected to a drive member (20, 50) for rotation of the drive member about the drive shaft (7, 52, 53). - Clutch components (23, 48) adapted to slidably connect the ring gear (15) to the planetary carrier (35) or to the drive components (20, 50), and - Braking members (24, 42) adapted to securely engage a portion of the planetary gear assembly (10, 31) with a locking portion (43) of the gear assembly (1, 30), In the low-speed range of the gear assembly, the clutch members (23, 48) and the brake members (24, 42) are operated such that torque is transmitted from the drive gears (9, 36) to the planetary gear assembly (10, 31), and reaches the drive members (20, 50) through the output stage of the planetary gear assembly (1, 31). In the high-speed range of the gear assembly, the clutch members (23, 48) and the brake members (24, 42) are operated such that the planetary carrier (12, 35) is fixedly connected to the drive member (20, 50) and rotates about the drive shaft (7, 52, 53), such that torque is transmitted from the drive gear (9, 36) to the drive member (20, 50) via the planetary carrier (12, 35).

2. The gear assembly (1, 30) according to claim 1, wherein, The drive gears (9, 36) include cylindrical gears rotatable about the drive shafts (7, 52, 53).

3. The gear assembly (1, 30) according to claim 1 or 2, in an electric vehicle, the drive shaft (7, 52, 53) includes a wheel axle, and the drive member (20, 50) includes a differential housing.

4. The gear assembly (1) according to claim 1 or 2, wherein the planetary gear assembly (10) includes an outer ring (15), the planetary gear members (13, 14) meshing with the outer ring (15) and with the sun gear (11), the outer ring being connectable to the drive member (20) via the clutch member (23), wherein the brake member (24) engages the outer ring (15).

5. The gear assembly (30) according to claim 1 or 2, wherein The planetary gear components (38, 39) are supported on the planet carrier (35) at spaced positions along the planet carrier axis so that they can rotate together about the planet carrier axis. - The drive gear (36) engages with the planet carrier (35) for the planet carrier to rotate about the drive shaft (52, 53). - The sun gear includes a first sun gear and the output stage includes a second sun gear; - The first sun gear (37) is rotatable around the drive shaft (52, 53) and meshes with the first planetary gear assembly (38) among the plurality of planetary gear assemblies (38, 39). - The second sun gear (40) is rotatable about the drive shaft (52, 53), is fixedly connected to the drive member (50), and meshes with the second planetary gear member (39) among the plurality of planetary gear members (38, 39). The braking member (42) is connected to the first sun gear (37) and the non-rotating locking portion (43) to prevent the first sun gear (37) from rotating about the drive shaft (52, 53) when the braking member (42) is engaged. - The clutch component (48) is arranged to connect the planetary carrier (35) to the drive component (50).

6. The gear assembly (30) according to claim 5, wherein The planetary gear components (38, 39) are supported on the planet carrier (35) at spaced positions along the planet carrier axis so that they can rotate together about the planet carrier axis. The drive gear (36) engages the first sun gear (37) for the first sun gear (37) to rotate about the drive shaft (52, 53), and the first sun gear (37) meshes with the first planetary gear assembly (38). - The second sun gear (40) is rotatable about the drive shaft (52, 53), is fixedly connected to the drive member (50), and meshes with the second planetary gear member (39). The braking member (42) is connected to the planetary carrier (35) and the non-rotating locking portion (43) to prevent the planetary carrier (35) from rotating about the drive shaft (52, 53) when the braking member (42) is engaged. - The clutch component (48) is arranged to connect the planetary carrier (35) to the drive component (50).

7. Electric vehicles, including - An electric motor (2, 32) having a rotor (33) and pinions (3, 34) rotatable about a rotor shaft (4) and a gear assembly (1, 30), the gear assembly (1, 30) being connected to the pinions (3, 34) via an input stage and to a drive shaft carrying one or more wheels (54, 55) via an output stage, the gear assembly (1, 30) comprising: - Drive gears (9, 36) connected to the pinions (3, 34), the drive gears (9, 36) being rotatable about the drive shaft (7, 52, 53), - A planetary gear assembly (10, 31) comprising a sun gear (11, 37, 40), two or more planetary gear members (13, 14, 38, 39), the two or more planetary gear members being supported on a planet carrier (12, 35) having a planet carrier shaft parallel to the rotor shaft (4) and being rotatable about their respective planetary gear shafts (18, 19), the planetary gear members (13, 14, 38, 39) meshing with one or more of the sun gear (11, 37, 40) and the ring gear (15), the input stage of the planetary gear assembly (10, 31) being connected to the drive gear (9, 36), and the output stage of the planetary gear assembly (10, 31) being connected to drive members (20, 50) for the drive gear to rotate about the transmission shaft (7, 52, 53). - Clutch components (23, 48) adapted to slidably connect the planetary carrier (12, 35) or the ring gear (15) to the drive components (20, 50), and - Braking members (24, 42) adapted to securely engage a portion of the planetary gear assembly with a locking portion (43) of the gear assembly (1, 30), In the low-speed range of the gear assembly, the clutch members (23, 48) and the brake members (24, 42) are operated such that torque is transmitted from the drive gears (9, 36) to the planetary gear assembly (1, 31), and reaches the drive members (20, 50) through the output stage of the planetary gear assembly (1, 31). In the high-speed range of the gear assembly, the clutch members (23, 48) and the brake members (24, 42) are operated such that the planetary carrier (12, 35) is fixedly connected to the drive member (20, 50) and rotates about the drive shaft (7, 52, 53), such that torque is transmitted from the drive gear (9, 36) to the drive member (20, 50) via the planetary carrier (12, 35).

8. The electric vehicle according to claim 7, comprising the gear assembly (1, 30) according to any one of claims 2 to 6.

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