Motor Unit Case Segmentation for Bearing Alignment
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Solution Overview
Problem
In saddle-type electric vehicles, the motor unit case tends to deflect due to warp or twisting of the vehicle body frame, leading to misalignment of motor bearings and increased rotational resistance, which is exacerbated by attempts to thin the case for weight reduction.
Innovation Solution
A motor unit case design where the power transmission mechanism is fastened to the vehicle body frame, while the motor accommodating section is joined to the transmission mechanism accommodating section in a cantilever state, with a cylindrical motor case having a smaller wall thickness and separate motor bearings to reduce deflection and misalignment, and an oil cooling system to efficiently cool the stator and power transmission components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the motor unit case is thinned to reduce weight, then the weight of the motor unit case is reduced, but the case becomes more susceptible to deflection and misalignment of motor bearings
Solution Approach 1:
The motor unit case is divided into two separate accommodating sections: a transmission mechanism accommodating section that is fastened to the vehicle body frame, and a motor accommodating section that is joined to the transmission mechanism accommodating section in a cantilever state. This segmentation allows the motor section to be lightweight while the transmission section provides stable mounting, resolving the contradiction between weight reduction and bearing alignment precision.
Solution Approach 2:
The transmission mechanism accommodating section acts as an intermediary between the vehicle body frame and the motor accommodating section. By joining the motor section to the transmission section rather than directly to the frame, the design allows the motor case to be thinner while the transmission section absorbs and compensates for frame deflections, maintaining bearing alignment.
2Stability of the object's composition
If the motor accommodating section is joined rigidly at both ends to the transmission mechanism accommodating section, then structural stability is improved, but the weight of the motor unit case increases
Solution Approach 1:
The motor accommodating section is joined to the transmission mechanism accommodating section with different degrees of rigidity at different locations: one end is joined rigidly to provide stability, while the other end is joined with lower rigidity to reduce weight and allow flexibility. This local differentiation of joint rigidity resolves the contradiction between structural stability and weight reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses deflection of the motor unit case, reduces misalignment of motor bearings, and minimizes rotational resistance, while maintaining a lightweight motor unit case by absorbing displacement through backlash in the gears and efficiently cooling the motor components.
Implementation Method 1
an oil cooling system to efficiently cool the stator and power transmission components
Implementation Method 2
absorbing displacement through backlash in the gears
Data Source
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AI summary
In a case where a motor shaft (32) of a driving electric motor (30) extends in a rightward and leftward direction, and one end portion in the rightward and leftward direction is coupled to a transmission (40), in a saddle-type electric vehicle such as an electric motorcycle 1, a transmission accommodating section (54) of a motor unit case (51) is fastened at right and left sides to a vehicle body frame, and a motor accommodating section (53) is coupled to the transmission accommodating section (54) at one end portion in the rightward and leftward direction. Thus, misalignment of bearings (33) of the motor shaft (32) due to deflection of the motor unit case (51) can be suppressed while reducing a weight of the motor unit case (51).