Cylindrical Motor Case Assembly for Power Transmission Alignment
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Solution Overview
Problem
Conventional power transmission units for lawn mowing vehicles have complex motor cases that increase manufacturing costs and are prone to misalignment, leading to noise and vibration issues during assembly.
Innovation Solution
A power transmission unit design featuring a motor case with a cylindrical shape and constant cross-section, directly coupled to a transmission case, which simplifies assembly and reduces manufacturing costs by eliminating the need for complex alignment and additional covers, while improving cooling performance through thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor case with a complicated shape is used to enclose the motor, then the motor can be properly enclosed and supported, but the manufacturing cost of the power transmission unit increases
Solution Approach 1:
The power transmission unit is divided into separate functional components: the transmission case enclosing the gear mechanism and the motor case enclosing the motor. These separate cases are then assembled together, allowing each to be manufactured independently with optimized shapes for their specific functions, reducing overall manufacturing complexity and cost.
Solution Approach 2:
The motor case and transmission case are merged into a single integrated assembly through direct coupling. This combination allows the benefits of separate manufacturing (simplified individual case shapes) to be realized while maintaining the functional integration of motor and transmission components.
2Reliability
If the motor case has a complicated shape to accommodate mounting features, then the motor can be securely mounted, but misalignment between the inner circumferential surface center axis and hole center axis occurs, making assembly difficult and increasing manufacturing cost
Solution Approach 1:
The mounting features are separated into different components: the inner circumferential surface is formed in the motor case while the corresponding hole is formed in the transmission case. This segmentation allows each component to be manufactured with simpler geometry and standard tolerances, avoiding the need for complex precision machining of a single integrated case.
Solution Approach 2:
The motor case acts as an intermediary component between the motor and the transmission case. It provides the mounting interface that couples the motor to the transmission case, absorbing any minor misalignments through its design and ensuring proper alignment without requiring extreme precision in either the motor case or transmission case individually.
3Reliability
If additional covers are added to enclose the motor, then the motor is better protected, but the device complexity and manufacturing cost increase
Solution Approach 1:
The motor case and transmission case are merged into a single enclosed assembly where the transmission case serves dual purposes: it encloses the gear mechanism and provides the outer protective housing. This eliminates the need for separate covers, reducing component count while maintaining protection of internal components.
Solution Approach 2:
The transmission case is designed to perform multiple functions: it encloses the gear mechanism, provides structural support, serves as a mounting surface for the motor case, and acts as the outer protective cover. This multi-functionality eliminates the need for dedicated cover components.
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
The design reduces manufacturing costs, enhances assembly efficiency, and minimizes noise and vibration by ensuring precise alignment of motor and transmission case components, thereby improving the overall performance and reliability of the power transmission unit.
Implementation Method 1
improving cooling performance through thermal conductivity
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A power transmission unit (41a) includes a motor (70); and a transmission case (42a) to enclose an input shaft (72), an output shaft (60), and a gear mechanism (80) that transmits driving power between the input shaft (72) and the output shaft (60). A motor case (120) attached to the transmission case (42a) on a side opposite the gear mechanism (80) of the transmission case has a cylindrical shape whose cross section is constant throughout a direction orthogonal to an axial direction of the motor case, and the motor (70) is placed inside the motor case.