Electric Fluid Pump Shaft Collar Embedding for Resin Casing Strength
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Solution Overview
Problem
Existing electric fluid pumps face issues with the connecting strength between the rotor shaft and the resin casing, leading to loosening and detachment due to bending and pulling forces, and lack a standard for precise positioning, resulting in reduced operating accuracy and increased vibrations.
Innovation Solution
The electric fluid pump design features a shaft member with a collar portion and stepped section, where the collar portion has a larger outer diameter than the shaft portion, and the stepped section serves as a bearing surface, enhancing the connecting strength and providing a standard for precise positioning, preventing loosening and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the axial length of the connecting portion between the rotary shaft and the resin casing is elongated, then the connecting strength therebetween is increased, but the electric fluid pump is increased in the axial length
Solution Approach 1:
The invention transitions from increasing connecting strength solely in the axial direction to utilizing the radial dimension by providing a collar portion with a larger outer diameter than the shaft portion. This radial expansion creates additional embedding area in the resin casing, thereby increasing connecting strength without necessarily increasing the axial length of the connecting portion.
Solution Approach 2:
The shaft member is segmented into distinct portions: a shaft portion, a collar portion with larger diameter, and a stepped section. This segmentation allows the collar portion to specifically engage with the resin casing for connection strength, while the shaft portion maintains a smaller diameter for compactness, thus resolving the contradiction between strength and length.
2Strength
If recessed and convex shapes are formed on the surface of the rotary shaft to improve engaging ability with resin, then the connecting strength is enhanced, but the rotor is not surely resistive against turning force and the rotary shaft may be gradually loosened
Solution Approach 1:
The shaft member is divided into functional segments: the collar portion with larger diameter provides the primary connection interface with the resin casing, while the shaft portion with smaller diameter serves the rotational function. This segmentation allows each portion to be optimized for its specific function, preventing the loosening issues that occur when relying solely on surface features of a uniform shaft.
Solution Approach 2:
Instead of relying only on surface features (zero-dimensional) or limited axial engagement (one-dimensional), the invention utilizes the radial dimension by providing a collar portion that extends outward with a larger diameter. This creates a two-dimensional engagement area with the resin casing, significantly improving resistance to turning forces and preventing gradual loosening.
3Device complexity
If no standard for positioning the rotary shaft relative to the casing is established, then the mold configuration can be simpler, but the rotary shaft is inaccurately positioned in the mold, deteriorating operating accuracy and causing vibrations
Solution Approach 1:
The collar portion with its larger outer diameter serves a dual function: it provides structural connection strength and acts as a self-positioning element during the molding process. The increased diameter creates a natural reference feature that aligns with the mold cavity, enabling accurate positioning without requiring additional complex positioning mechanisms in the mold.
Solution Approach 2:
The collar portion is designed to perform multiple functions simultaneously: it provides mechanical connection strength through embedding in the resin, serves as a bearing surface location feature, and acts as a positioning reference during molding. This multi-functionality eliminates the need for separate positioning features, simplifying the mold configuration while maintaining high positioning accuracy.
Data Source
Figure 1
Figure 2~3
Figure 4A~5
AI summary
An electric fluid pump (P) includes a casing (2), a rotor (3) arranged in the casing (2), and a shaft member (1) supported by the casing (2) and including a shaft portion (11) extending in the casing (2) in a direction of an axis (L) of the shaft member (1), having a first end portion (14) arranged at one axial end of the shaft member (1) and a second end portion (15) arranged at the other axial end of the shaft member (1), and supporting the rotor (3), a collar portion (12) arranged at the first end portion (14) of the shaft portion (11) and embedded in the casing (2), and a stepped section (13) arranged between the shaft portion (11) and the collar portion (12), positioned closer to the second end portion (15) of the shaft portion (11) than the first end portion (14) of the shaft portion (11), and configured to have an end face facing the second end portion (15) and serving as a bearing surface (13a) on which the rotor (3) is rotatably supported.