Brushless Motor Stator Bushing Assembly for Low Press-In Mounting
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Solution Overview
Problem
Existing drive devices for motor vehicles, particularly window lifters, face challenges in achieving low press-in forces for mounting the stator in the gearbox housing while ensuring reliable radial and axial positioning of the stator.
Innovation Solution
A drive device with a brushless electric motor in an external rotor embodiment, featuring a stator bush with a form-fitting and force-fitting connection to the gearbox housing, utilizing an annular element with joining elements that engage in corresponding contours, and a slot cell insulation with molded plastic parts for secure positioning and reduced press-in forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional stator mounting method is used, then the stator can be mounted in the gearbox housing, but high press-in forces are required which risk damaging the stator or housing
Solution Approach 1:
The stator mounting system is segmented into multiple functional components: the stator bush with power take-off type first sleeve portion, the annular element with joining elements, and the slot cell insulation. This segmentation allows each component to perform its specific function - the first sleeve portion provides form-fitting connection, the annular element provides force-fitting connection, and the slot cell insulation provides electrical isolation - thereby achieving reliable mounting without excessive press-in forces
Solution Approach 2:
The stator bush acts as an intermediary component between the stator and the gearbox housing. It translates the mounting requirements into a form-fitting connection geometry that distributes press-in forces evenly, preventing localized stress concentrations that could damage the stator or housing while ensuring reliable mounting
2Reliability
If the stator is securely positioned in the gearbox housing, then radial and axial positioning is reliable, but the assembly complexity increases
Solution Approach 1:
Multiple functions are merged into integrated components: the stator bush combines the power take-off type first sleeve portion for form-fitting connection with the second sleeve portion for force-fitting connection, and the annular element integrates joining elements that engage with both the stator bush and slot cell insulation. This merging reduces the number of separate parts and simplifies assembly while maintaining reliable positioning
Solution Approach 2:
The stator bush serves multiple functions simultaneously: it provides the form-fitting connection geometry for radial positioning, supports the power take-off type first sleeve portion for torque transmission, and guides the second sleeve portion for axial positioning. This multi-functionality reduces the need for additional specialized components, thereby simplifying the overall assembly
Data Source
AI summary
A drive device has a transmission housing with an external rotor-type electric motor. The electric motor is coupled to the transmission and is actuated by a motor electronic unit. The electric motor has a stator and a rotor which circulates about the stator and is connected to a drive shaft that is guided through a stator bushing with a first sleeve section for holding the stator bushing in the transmission housing in a rotationally fixed manner and with a second sleeve section. A groove frame insulation which surrounds the stator teeth in the axial direction is placed on the second sleeve section. An annular element which is arranged between the first sleeve section and the groove frame insulation and which has a joint element is placed on the second sleeve section of the stator bushing. The joint element engages into a joint contour of the first sleeve section.