Electric Drive Unit Housing Structure for Bending Load Isolation
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Solution Overview
Problem
The integration of an electric motor into an electric drive unit as a structural element leads to cyclic bending stresses and potential damage to cooling system components, such as pumps or heat exchangers, due to the transmission of beaming loads and external mounting, which affects durability and risk of damage during vehicle operation.
Innovation Solution
The electric drive unit design includes a housing assembly with a motor assembly, transmission, differential assembly, and output shafts, where the motor housing is spaced apart from the perimeter wall and axle tube mounts, allowing for a separate motor cavity and coolant channels to mitigate stress and protect cooling components, with a lubrication and cooling system that includes a pump, heat exchanger, and filter to manage fluid circulation and cooling effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the electric motor housing is integrated as a structural element to transmit beaming loads, then the weight of the electric drive unit is reduced and integration is improved, but cyclic bending stresses are applied to motor components and durability is reduced
Solution Approach 1:
The housing assembly is segmented into distinct functional zones: a motor housing that is spaced apart from structural mounting points, and separate perimeter wall members and axle tube mounts that handle beaming loads. This segmentation allows the motor housing to be isolated from cyclic bending stresses while maintaining overall structural integrity through the distributed mounting architecture.
2Ease of operation
If cooling system components are mounted to the exterior of the housing assembly, then accessibility and integration are improved, but risk of damage from external impacts increases
Solution Approach 1:
The patent introduces an intermediate protective structure where cooling system components are mounted within the protected interior space of the housing assembly, shielded by the perimeter wall members and end covers. This intermediary protective barrier separates the cooling components from external impacts while maintaining accessibility through designated service access points in the housing structure.
3Reliability
If the motor housing is spaced apart from the perimeter wall and axle tube mounts, then cyclic stress on motor components is reduced, but structural complexity increases
Solution Approach 1:
The perimeter wall members and end covers serve multiple functions: they provide structural support for transmitting beaming loads through the housing assembly, define the protected interior space, and create mounting surfaces for cooling system components. This multi-functionality reduces the need for additional specialized structural elements, thereby limiting the increase in overall structural complexity despite the spaced-apart motor housing configuration.
Data Source
AI summary
An electric drive unit having an electric motor, a differential assembly, a transmission, which transmits rotary power between the electric motor and the differential assembly, a pair of axle shafts, which are drivingly coupled to output members of the differential assembly, and a housing assembly in which the electric motor, the differential assembly, the transmission, and the axle shafts are housed. The electric motor includes a stator, a rotor and a motor housing that houses the stator and the rotor. The motor housing is fixedly coupled the housing assembly. Bending loads transmitted through the motor housing are not transmitted through the electric motor.