Electric drive for a mobile vehicle

Abstract

Electric drive for a mobile vehicle with an electric motor (1) which drives two outputs (10, 11) via a spur gear transmission (3, 4, 6, 7) and a differential transmission (9), characterized in that a housing encloses the differential transmission (9), the spur gear transmission (3, 4, 6, 7) and the motor (1), wherein the housing consists of three main housing parts (12, 13, 14), wherein a middle housing part (12) has a cylindrical extension (15) in which the electric motor (1) is arranged, which is closed at one end with a cover-shaped housing part (13) and has at the other end an extension (16) arranged parallel to the cylindrical extension (15) in which the differential transmission (9) and the spur gear transmission (3, 4, 6, 7) are arranged, and this extension (16) is closed with a further cover-shaped housing part (14), characterized in thatthat a motor shaft (2) and a first spur gear (3) are integrally connected.

Description

[0001] The invention relates to an electric drive for a mobile vehicle with an electric motor according to the preamble of claim 1. Electric drives for mobile vehicles are used, for example, as sole drives or auxiliary drives for rear axles in passenger cars.

[0002] DE 100 49 514 B4 discloses an electric drive for a rear axle of a passenger car, in which an electric drive motor drives a differential gear via a spur gear transmission, the output of which drives the wheels of the vehicle.

[0003] DE 10 2005 022 926 B3 describes a drive unit for a motor vehicle with an electric drive motor and a transmission, which are housed in a common casing.

[0004] DE 201 07 385 U1 describes a design for a torsion circuit for vehicles.

[0005] The present invention is based on the objective of creating an electric drive for a mobile vehicle which is cost-effective in design and easy to assemble.

[0006] The problem is solved by the features of main claim 1. Advantageous embodiments are specified in the dependent claims.

[0007] The invention is defined by the features of the main claim.

[0008] The electric drive has an electric motor which drives two outputs of the differential via a spur gear and a differential, through which, for example by means of drive shafts, the wheels of the vehicle are driven.

[0009] The electric drive unit comprises a housing that encloses the differential, the spur gear, and the electric motor. The housing consists of a central section that accommodates the electric motor on one side and, essentially, the spur gear and differential on the other. Cover-shaped housing sections are attached to both ends of the central section, closing it off. The central section features a cylindrical extension in which the motor is located, and a parallel extension in which the spur gear and differential are located. This creates a vertical offset between the motor shaft of the electric motor and the output shaft or any output shafts connected to it.

[0010] In a further embodiment of the invention, cooling channels are arranged in the middle part of the housing to cool the electric motor.

[0011] Preferably, four main cooling channels are arranged parallel to the axis of rotation of the electric motor's drive shaft in the central housing section. These channels are designed to fill the space between the round rotor of the electric motor and the square outer contour of the central housing that surrounds the electric motor. To ensure coolant flow through the housing and to design the housing for casting, two connecting channels, arranged perpendicular to the axis of rotation of the electric motor's drive shaft, are located on the two end faces of the central housing section. These connecting channels link two main cooling channels each and are sealed with plugs after drilling. The coolant inlet is located on one of the two end faces, from which the coolant flows into one of the four main cooling channels.In this main cooling channel, the coolant flows through the central housing section to the opposite end face. There, it is routed through the connecting channel into another main cooling channel and flows back through the central housing section to the first end face, where it is redirected again. The coolant continues to flow through the channels until it exits the return line on the first end face, which is located on the same side as the coolant inlet. This results in a meandering flow of the coolant through the central housing section.

[0012] In a further embodiment of the invention, the central housing part has recesses for power electronics for the electric motor. Furthermore, it is possible to arrange sealing elements between the electric motor and the spur gear unit, thus keeping the electric motor oil-free.

[0013] The spur gear transmission can consist of four spur gears, wherein a first spur gear is non-rotatably connected to the motor shaft of the electric motor and is operatively connected to a second spur gear, which is non-rotatably connected to a third spur gear and rotatably mounted via an intermediate shaft, wherein the third spur gear is operatively connected to a fourth spur gear, which is non-rotatably connected to the differential. It is possible that the fourth spur gear is connected to a differential housing of the differential via a metallurgical bond.

[0014] In another embodiment, the motor shaft is integrally connected to the first spur gear, meaning that the first spur gear and the motor shaft only require two bearing points. When an additional parking lock is used, with the parking lock wheel mounted on the motor shaft, the motor shaft is supported by three bearing points: one at one end of the motor shaft, one at the other end, and one between the motor rotor and the first spur gear.

[0015] Further characteristics can be found in the character description.

[0016] They show: Fig. 1 a section through the electric drive; Fig. 2 a rear view of the electric drive and Fig. 3 A front view of the electric drive. Fig. 1:

[0017] An electric motor 1 drives a first spur gear 3 via its motor shaft 2. The first spur gear 3 is operatively connected to the second spur gear 4, which is non-rotatably connected to a third spur gear 6 via an intermediate shaft 5. The third spur gear 6 is operatively connected to the fourth spur gear 7, which is non-rotatably connected to a differential carrier 8 of the differential 9. Vehicle wheels can be driven via a first output 10 and a second output 11. The housing of the electric drive consists of a central housing part 12, a cover-shaped housing part 13, and another cover-shaped housing part 14. The cover-shaped housing part 13 is located at one end of the central housing part 12, and the cover-shaped housing part 14 is located at the other end of the central housing part 12.The central housing part 12 consists of a cylindrical extension 15, in which the motor 1 is arranged, and an extension 16 arranged parallel to the cylindrical extension 15, in which the differential 9 is arranged. The motor shaft 2 is supported on one side by the bearing 17 in the cover-shaped housing part 13 and on the other side by the bearings 18 and 19 in the central housing part 12 and in the further cover-shaped housing part 14. If there is no parking lock gear on the motor shaft 2, the motor shaft 2 and the first spur gear 3, which is integrally connected to it, can also be supported only by the bearing 17 in the housing part 12 and the bearing 18 in the housing part 12. The bearing 19 can therefore be omitted. The intermediate shaft 5 is supported on one side by the bearing 20 in the central housing part 12 and on the other side by the bearing 21 in the further cover-shaped housing part 14.The differential 9 is mounted via bearings 22 and 23 in the central housing part 12 and in the further cover-shaped housing part 14. The first spur gear is arranged axially along the motor shaft between the electric motor 1 and the fourth spur gear 7. Fig. 2:

[0018] The middle housing part 12 has a reinforcing rib 24 in the area of ​​the differential gear 9, which connects the extension 16 with the cylindrical extension 15. Fig. 3:

[0019] The further lid-shaped housing part 14 has reinforcing ribs 25 in the area of ​​the differential gear 9, which run radially around the axis of rotation of the second output 11. Reference sign 1 electric motor 2 Motor shaft 3 first spur gear 4 second spur gear 5 Intermediate shaft 6 third spur gear 7 fourth spur gear 8 Differential basket 9 Differential gears 10 first drive 11 second drive 12 middle housing part 13 lid-shaped housing part 14 additional lid-shaped housing parts 15 cylindrical extension 16 Extension 17 warehouses 18 warehouses 19 warehouses 20 warehouses 21 warehouses 22 warehouses 23 warehouses 24 Steg 25 ribs

Claims

[1] Electric drive for a mobile vehicle with an electric motor (1) which drives two outputs (10, 11) via a spur gear (3, 4, 6, 7) and a differential gear (9), characterized by , that a housing encloses the differential gear (9), the spur gear (3, 4, 6, 7) and the motor (1), wherein the housing consists of three main housing parts (12, 13, 14), wherein a middle housing part (12) has a cylindrical extension (15) in which the electric motor (1) is arranged, which is closed at one end with a cover-shaped housing part (13) and has at the other end an extension (16) arranged parallel to the cylindrical extension (15), in which the differential gear (9) and the spur gear (3, 4, 6, 7) are arranged, and this extension (16) is closed with a further cover-shaped housing part (14), characterized by, that a motor shaft (2) and a first spur gear (3) are integrally connected. [2] Electric drive according to claim 1, characterized by , that a motor shaft (2) is rotatably mounted in the lid-shaped housing part (13) in the middle housing part (12) and in the further lid-shaped housing part (14). [3] Electric drive according to claim 1, characterized by , that the spur gear transmission consists of four spur gears, wherein the first spur gear (3) is non-rotatably connected to the motor shaft (2), and a second spur gear (4) is operatively connected to the first spur gear (3) and non-rotatably connected to an intermediate shaft (5), and a third spur gear (6) is also non-rotatably connected to the intermediate shaft (5) and is operatively connected to a fourth spur gear (7), which is non-rotatably connected to the differential gear (9). [4] Electric drive according to claim 1, characterized by, that the intermediate shaft (5) is rotatably mounted in the further lid-shaped housing part (14) and in the middle housing part (12). [5] Electric drive according to claim 1, characterized by , that the differential gear (9) is rotatably mounted in the further lid-shaped housing part (14) and in the middle housing part (12). [6] Electric drive according to claim 1, characterized by , that the axes of rotation of the outputs (10, 11) are arranged parallel to the axis of rotation of the motor shaft (2). [7] Electric drive according to claim 1, characterized by , that cooling channels are arranged in the middle housing part (12). [8] Electric drive according to claim 1, characterized by , that the fourth spur gear (7) is materially connected to a differential basket (8) of the differential gear (9). [9] Electric drive according to any one of claims 1 to 8, characterized by , that the motor shaft (2) is supported by two bearing points (17, 18). [10] Electric drive according to any one of claims 1 to 8, characterized by , that the motor shaft (2) is supported by three bearing points (117, 18, 19) when using a parking lock.

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