DE102023201201A1 - Electric motor for an electric vehicle - Google Patents

Abstract

The invention relates to an electric motor for an electric vehicle with an excitation unit 1, a rotor with a hollow rotor shaft 2, a bearing 3 and a motor housing 4, wherein the excitation unit 1 is arranged within the hollow rotor shaft 2 and the rotor shaft 2 is mounted in the motor housing 4 via the bearing 3, characterized in that the rotor shaft 2 is in several parts, consisting of a shaft body 21 and a shaft end cap 22, wherein the excitation unit 1 is arranged in the shaft body 21, the bearing 3 is arranged on a first shaft shoulder 221 of the shaft end cap 22 and the shaft body 21 has a larger body diameter d1 than the first shaft shoulder 221 of the shaft end cap 22 and a shoulder diameter d2.

Description

The invention relates to an electric motor for an electric vehicle. The field of application of the invention lies particularly in the automotive industry in the field of electric or hybrid vehicles.

An important aspect in the development and production of electric motors for electric vehicles is the limited installation space in the area around the electric motor. Since a large number of components, such as an excitation unit, power electronics or a gearbox, have to be arranged in the installation space around the electric motor and long paths for electrical currents and mechanical torques should be avoided for efficiency reasons, compromises usually have to be made between the installation space required for the electric motor and the efficiency of the electric motor.

In order to save installation space for the components mentioned in electric motors, some components can be arranged at least partially within a hollow rotor shaft of the rotor of the electric motor. This can reduce the installation space required for the components, in particular for the excitation unit, and reduce the paths for mechanical torques and electrical currents. However, the problem when assembling the electric motors is that the excitation unit is very difficult to access, which makes assembling the electric motor and any maintenance and/or repairs considerably more difficult. It is also advantageous if the bearings of the rotor shaft have a smaller bearing diameter, as this reduces bearing losses, which improves the efficiency of the electric motor. However, by using smaller bearings, the bearings can no longer sit on an outer diameter of the rotor shaft. In addition, the components arranged in the rotor shaft must be protected against mechanical influences and vibrations that inevitably occur in the vicinity of the rotor shaft due to the tolerances caused by production and assembly.

It is the object of the invention to provide an electric motor for an electric vehicle in which the excitation unit is accessible for repairs and assembly and which has improved efficiency compared to conventional electric motors. It is also the object of the invention to provide a drive axle for an electric vehicle and a vehicle.

The object is achieved by an electric motor for an electric vehicle with an excitation unit, a rotor with a hollow rotor shaft, a bearing and a motor housing, wherein the excitation unit is arranged within the hollow rotor shaft and the rotor shaft is mounted in the motor housing via the bearing, in that the rotor shaft is multi-part, consisting of a shaft body and a shaft end cap and wherein the excitation unit is arranged in the shaft body, the bearing is arranged on a first shaft shoulder of the shaft end cap and the shaft body has a larger body diameter than the first shaft shoulder of the shaft end cap has a shoulder diameter.

By dividing the rotor shaft into a shaft body and a shaft end cap, the excitation unit can be integrated into the rotor shaft stub and the accessibility of the excitation unit can be ensured simply by removing the shaft end cap. This makes installation and/or maintenance or repair of the excitation unit much easier. The excitation unit is inserted into the shaft body, which is open on one side, during the assembly process and the shaft body is then closed with the shaft end cap. The bearing is then arranged on the shaft end cap.

Advantageously, the shaft end cap has a second shaft shoulder which projects into the shaft body and there is a tolerance compensation element which is arranged between the excitation unit and the second shaft shoulder.

Preferably, the shaft end cap has a shaft collar between the first shaft shoulder and the second shaft shoulder, which has a collar diameter that is the same as the body diameter. In this case, the shaft collar rests against an end face of the shaft body. The bearing is fixed between the motor housing and the shaft collar on the first shaft shoulder. The diameters always refer to the outside diameters of the corresponding components.

The tolerance compensation element can in principle be designed as any tolerance compensation element known from the prior art. The tolerance compensation element is preferably a spring, particularly preferably it is a wave spring.

The object is also achieved by a drive axle for an electric vehicle, which has an electric motor according to one of the described embodiments.

The task is also solved by an electric vehicle with the drive axle described.

• 1 Eine Draufsicht auf einen Ausschnitt einer Ausführung eines Elektromotors mit einer Anregeeinheit, einer Rotorwelle, einem Lager, einem Motorgehäuse und einem Toleranzausgleichselement.

The invention is explained in more detail below using an exemplary embodiment. It shows:

• 1 A plan view of a section of an embodiment of an electric motor with an excitation unit, a rotor shaft, a bearing, a motor housing and a tolerance compensation element.

1 shows an embodiment of an electric motor with an excitation unit 1, a hollow rotor shaft 2, a bearing 3, a motor housing 4 and a tolerance compensation element 5. The excitation unit 1 is arranged inside the rotor shaft 2. The rotor shaft 2 is mounted in the motor housing 4 via the bearing 3 and is made up of several parts. It consists of a shaft body 1 with a body diameter d ₁ and a shaft end cap 22 with a first shaft shoulder 221 which has a shoulder diameter d ₂ . The body diameter d ₁ is larger than the shoulder diameter d ₂ .

Camp 3 is located in 1 shown design is designed as a ball bearing. In principle, however, any suitable bearing design known from the state of the art can be used as bearing 3.

The shaft end cap 22 also has a second shaft shoulder 222 that projects into the shaft body 21. The second shaft shoulder 222 rests against an inner circumferential surface of the shaft body 21. The dimensions and arrangements of the shaft body 21 and the second shaft shoulder 222 are coordinated with one another in such a way that the excitation unit 1 sits in the interior of the cavity of the shaft body 21 with only a small amount of play and a bearing with a bearing seat diameter optimized for the requirements is arranged on the second shaft shoulder 22.

A tolerance compensation element 5 is provided between the excitation unit 1 and the second shaft shoulder 222 in order to compensate for manufacturing and assembly-related tolerances that occur during the manufacture and assembly of the electric motor. The tolerance compensation element 5 ensures that all components integrated into the rotor shaft 2, but in particular the excitation unit 1, are protected, especially against mechanical influences and/or vibrations that occur on the rotor shaft.

The shaft end cap 22 also has a shaft collar 223 between the first shaft shoulder 221 and the second shaft shoulder 222. The shaft collar 223 has a collar diameter d ₃ that is equal to the body diameter d _1. The different diameters are shown in the 1 indicated by double arrows.

The tolerance compensation element 5 is in the 1 The version shown has a wave spring. The excitation unit 1 is secured by the wave spring.

Reference symbols

1

Excitation unit

2

Rotor shaft

21

Wave hull

22

Shaft end cap

221

first wave paragraph

222

second wave paragraph

223

Wave collar

3

Warehouse

4

Engine housing

5

Tolerance compensation element

d1

Hull diameter

d2

Shaft end diameter

d3

Collar diameter

Claims (6)

Electric motor for an electric vehicle with an excitation unit (1), a rotor with a hollow rotor shaft (2), a bearing (3) and a motor housing (4), wherein the excitation unit (1) is arranged within the hollow rotor shaft (2) and the rotor shaft (2) is mounted in the motor housing (4) via the bearing (3), characterized in that the rotor shaft (2) is made up of several parts, consisting of a shaft body (21) and a shaft end cap (22), wherein the excitation unit (1) is arranged in the shaft body (21), the bearing (3) is arranged on a first shaft shoulder (221) of the shaft end cap (22) and the shaft body (21) has a larger body diameter (d ₁ ) than the first shaft shoulder (221) of the shaft end cap (22) has a shoulder diameter (d ₂ ). Electric motor according to Claim 1 , characterized in that the shaft end cap (22) has a second shaft shoulder (222) which projects into the shaft body (21) and a tolerance compensation element (5) is present which is arranged between the excitation unit (1) and the second shaft shoulder (222). Electric motor according to Claim 2 , characterized in that the shaft end cap (22) has a shaft collar (223) between the first shaft shoulder (221) and the second shaft shoulder (222) which has a collar diameter (d ₃ ) equal to the body diameter (d ₁ ). Electric motor according to Claim 2 , characterized in that the tolerance compensation element (5) is a wave spring. Drive axle for an electric vehicle, which has an electric motor according to one of the Claims 1 until 4 has. Electric vehicle with a drive axle according to Claim 5 .

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