Gearbox assembly for an electric motor and electric motor

Abstract

The invention relates to a gear assembly (10) for an electric motor (100), comprising a shaft section (32) rotatably mounted about an axis (24), a first gear wheel section (42) connected to the shaft section (32) and having a first toothed area (46) on its outer circumference, and a second gear wheel section (44) arranged at a distance from the first gear wheel section (42) in the direction of the axis (24), which is connected to the shaft section (32) and has a second toothed area (48) on its outer circumference.

Description

Technical area

[0001] The invention relates to a transmission assembly for an electric motor, characterized by a particularly advantageous manufacturing process. Furthermore, the invention relates to an electric motor with a transmission assembly designed according to the invention, in particular as a component of a drive train of an electric vehicle. State of the art

[0002] Gear assemblies for electric motors serve to reduce the speed of the electric motor while simultaneously increasing torque. In electric vehicles, for example, they are located between the drive shaft of the electric motor and a differential connected to the driven wheels. Typically, such a gear assembly has at least one shaft section rotatably mounted about a longitudinal axis, on which two gear wheels are arranged axially spaced from each other along the longitudinal axis of the shaft section. The gear sections have different diameters and each has toothed sections on its outer circumference that mesh, for example, with an output pinion of the electric motor's drive shaft and another gear (of the differential).The shaft section and the two gear wheels each form separate components, typically made of steel, and are joined together to form a rigid unit. This requires manufacturing the components, at least in their connection areas, to the appropriate tolerances and, if necessary, incorporating positive-locking geometries or similar features. Such a manufacturing process is relatively complex. Disclosure of the invention

[0003] The inventive gear assembly for an electric motor with the characterizing features of claim 1 has the advantage that it can be manufactured in a particularly advantageous manner with relatively low production costs. The invention is based on the idea of ​​replacing the separately manufactured and interconnected individual parts typically used in conventional gear assemblies with a monolithic component that performs the aforementioned functional tasks of the components and thus eliminates the assembly effort required for assembling the components.

[0004] In light of the above explanations, a gear assembly according to the invention for an electric motor with the features of claim 1 is therefore provided in that the shaft section, together with the first gear wheel section and the second gear wheel section, is designed as a monolithic component in the form of a sintered component. Within the scope of the invention, a sintered component means the use of metallic powder to achieve the required strengths or to transmit the required torques of the gear assembly.

[0005] Advantageous further developments of the gear assembly according to the invention for an electric motor are listed in the dependent claims.

[0006] In a further development of the invention, which advantageously implements additional components of the gear assembly in the form of a sintered component, it is provided that the first and / or second gear teeth interact with a gear designed as a sintered component, wherein the gear is connected to a shaft designed as a rotating part. This shaft can, in particular, also be a drive shaft of the electric motor. The advantage of this design is that, compared to conventional shafts where the gear is made of steel with relatively high strength requirements and thus high alloy content, the shaft can be made of a lower-grade steel that is only capable of reliably transmitting the required torque to the gear. In contrast, the gear designed as a sintered component can, through the use of appropriate sintered materials, achieve the increased strength properties of the shaft or drive shaft.

[0007] Steel powder with alloying elements is particularly suitable as a material for the monolithic component of the gearbox assembly. By selecting appropriate alloying elements, a particularly advantageous design of the sintered component can be achieved with ease, for example, with regard to wear, strength, and lubrication properties.

[0008] The assembly described above, designed as a sintered component, typically only requires that its gear teeth and end sections serving as bearing areas be finished, in particular ground. Therefore, a typical manufacturing process for the gear assembly comprises only three steps: pressing the metal powder into a so-called green compact, the actual sintering process, and finally, the finishing.

[0009] The invention further comprises an electric motor with a transmission assembly designed according to the invention as described above. Preferably, the electric motor is designed as a drive motor for an electric vehicle.

[0010] Further advantages, features and details of the invention will become apparent from the description of preferred embodiments of the invention and from the drawing. Brief description of the drawing Fig. Figure 1 shows a longitudinal section through an electric motor in the area of ​​a gearbox assembly. Embodiments of the invention

[0011] In the Fig. Figure 1 shows a gearbox assembly 10 for an electric motor 100. The gearbox assembly 10 or the electric motor 100 is preferably used in the context of electromobility, in particular as a component of a drive motor for an electric vehicle.

[0012] The gearbox assembly 10 is arranged within a housing 12, which is closed by means of a housing cover 14. A drive shaft 16 of the electric motor 100, shown only in section, is visible inside the housing 12. A gear in the form of an output pinion 20, designed as a sintered component, is arranged or attached to the shaft end of the drive shaft 16, which is rotatable about a pivot axis 18. In contrast, the drive shaft 16 is designed as a turned part made of steel.

[0013] The essential part of the gear assembly 10 comprises a monolithic component 22, formed as a sintered component, which is rotatably mounted about an axis 24 arranged parallel to the axis of rotation 18. The rotational speed of the output pinion 20 can be transmitted to a differential assembly 30 by means of the gear assembly 10 or the component 22, thereby increasing torque and reducing rotational speed.

[0014] Component 22 has a shaft section 32, the two end sections 34, 36 of which are rotatably mounted in bearing arrangements 38, 40 designed as tapered roller bearings in the housing 12. After the sintered component is manufactured, the end sections 34, 36 of component 22 are typically finished or ground before being connected to the bearing arrangements 38, 40. Between the two axially spaced end sections 34, 36 of the shaft section 32, two gear wheel sections 42, 44 are arranged adjacent to each other in the axial direction. The first gear wheel section 42 serves to mesh with the teeth of the output pinion 20. For this purpose, the first gear wheel section 42 has a first toothed section 46 on its outer circumference. Likewise, the second gear section 44 has a second toothed area 48 on its outer circumference, which meshes with the outer toothing 50 of a gear wheel 52 of the differential.The two gear areas 46, 48 of the sintered component or component 22, as well as the end sections 34, 36, are subjected to finishing, in particular a grinding process, after the sintering process.

[0015] By selecting the appropriate steel powder or alloying elements added to the steel powder, it is advantageous to achieve both the durability or wear resistance and the lubrication properties of component 22 in the gearbox assembly 10.

[0016] The gear assembly 10 or component 22 described so far, in particular its geometry, can be modified or adapted in a variety of ways without deviating from the inventive concept.

Claims

[1] Gear assembly (10) for an electric motor (100), comprising a shaft section (32) mounted rotatably about an axis (24), a first gear section (42) which is connected to the shaft section (32) and which has a first toothed region (46) on its outer circumference, a second gear section (44) which, viewed in the direction of the axis (24), is arranged at a distance from the first gear section (42), which is connected to the shaft section (32) and which has a second toothed region (48) on its outer circumference, characterized by that the shaft section (32) together with the first gear section (42) and the second gear section (44) is designed as a monolithic component (22) in the form of a sintered component. [2] Gearbox assembly according to claim 1, characterized bythat the first and / or second toothed region (46, 48) cooperates with a gear (20) designed as a sintered component, wherein the gear (20) is connected to a shaft (16) designed as a rotating part. [3] Gearbox assembly according to claim 2, characterized by that the shaft (16) is a drive shaft of the electric motor (100). [4] Gearbox assembly according to one of claims 1 to 3, characterized by that the monolithic component (22) and / or the gear (20) consists of steel powder with alloy components. [5] Gear assembly according to one of claims 1 to 4, characterized by that the toothing regions (46, 48) and end sections (34, 36) of the monolithic component (22) serving for the bearing are finished, in particular ground. [6] Electric motor (100) with a gear assembly (10) designed according to one of claims 1 to 5. [7] Electric motor according to claim 6, characterized bythat the electric motor (100) is designed as a drive motor for an electric vehicle.

Images