Motor Case Large Diameter Portion Water Corrosion
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Solution Overview
Problem
Existing drive apparatuses are prone to corrosion when exposed to water due to water flow along the motor case, which can lead to corrosion of the connection between the motor case and the external gear device.
Innovation Solution
The drive apparatus features a motor case with a large diameter portion at the bottom portion that is larger than the stator fixation location, forming a continuous contact surface with the external device housing, preventing water from reaching the boundary surface and reducing corrosion risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor case is installed to the housing through the bottom portion, then the connection between the motor case and external device is established, but water flows along the motor case and reaches the installation surface, causing corrosion
Solution Approach 1:
The patent introduces a large diameter portion that protrudes radially outward from the motor case, creating a stepped structure. This dimensional change in the radial direction blocks water flow along the motor case, preventing water from reaching the installation surface where corrosion occurs. The large diameter portion acts as a water shield by changing the flow path in the radial dimension.
Solution Approach 2:
The large diameter portion serves as an intermediary structure between the motor case and the external device housing. It creates a physical barrier that intercepts water flow before it can reach the critical installation surface, thereby protecting the connection from corrosion while maintaining the functional connection.
2Reliability
If a large diameter portion is formed at the bottom portion of the motor case, then water flow is blocked and corrosion is prevented, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
The patent modifies the geometric parameters of the motor case by introducing a large diameter portion with a specific outer diameter that is larger than the stator fixation location. This parameter change creates the water-blocking function while maintaining a simple stepped cylindrical structure that is easy to manufacture using conventional machining or forming processes.
3Object-affected harmful factors
If the large diameter portion protrudes radially outward, then water is effectively blocked from reaching the boundary surface, but the overall size of the motor case increases
Solution Approach 1:
The motor case is segmented into two distinct portions: a standard diameter tubular portion for housing the stator and a large diameter portion for water protection. This segmentation allows the water-blocking function to be added only where needed at the bottom portion, rather than increasing the diameter of the entire motor case, thus minimizing the overall footprint increase.
Data Source
AI summary
An electric motor includes: a stator; windings wound around the stator; a rotor configured to rotate relative to the stator; a shaft; and a motor case. The shaft is configured to rotate integrally with the rotor, and one end portion of the shaft is coupled to a speed reducing gear device. The motor case includes a tubular portion and a bottom portion, and an opposite side of the tubular portion, which is opposite to the bottom portion, opens. A large diameter portion is formed at an outer periphery of the bottom portion of the motor case and has an outer diameter, which is larger than an outer diameter of a stator fixation location of the motor case, to which the stator is fixed, while the large diameter portion is formed continuously with a contact surface of the bottom portion that is configured to contact a gear housing.