Fuel Pump Motor Rotor Core Collar Design for Compact Coil Winding
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Solution Overview
Problem
Existing fuel pump designs face challenges in downsizing while maintaining torque and efficiency, particularly in securing space for coil windings between the commutator and rotor core without elongating the pump axially, and in preventing rotor core displacement during resin molding.
Innovation Solution
The design incorporates a rotor core with collar portions at the axial ends, allowing coil winding between the commutator and rotor core, and uses a resin member with a radially recessed boundary to prevent axial displacement during molding, enhancing magnetic flux and torque without increasing the motor's axial length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a disc-shaped commutator is used to downsize the fuel pump, then the outer diameter is reduced, but it becomes difficult to secure space for coil windings between the commutator and rotor core
Solution Approach 1:
The rotor core is designed with an inclined outer circumferential periphery that slopes toward the commutator, creating a tapered winding space. This dimensional change in the rotor core geometry provides adequate room for coil windings while maintaining the compact disc-shaped commutator structure, thus achieving downsizing without compromising coil winding space.
2Device complexity
If the distance between commutator and rotor core is axially extended to secure coil winding space, then coil winding space is adequate, but the fuel pump becomes axially elongated
Solution Approach 1:
Instead of increasing the axial distance between commutator and rotor core, the invention changes the radial/dimensional geometry of the rotor core by inclining its outer circumferential periphery. This creates sufficient winding space in the radial and circumferential directions while maintaining a compact axial length, thus avoiding pump elongation.
Solution Approach 2:
The rotor core features a localized inclined surface on its outer circumferential periphery that specifically addresses the coil winding space requirement in the critical region near the commutator, while the rest of the rotor core maintains its original geometry to preserve overall compactness.
3Manufacturing precision
If high molding pressure is applied during resin injection to ensure proper filling, then resin fills adequately, but the rotor core may be displaced axially relative to the rotation shaft
Solution Approach 1:
A resin prevention portion (protrusion) is pre-formed on the rotation shaft at the location where the rotor core will be positioned. This preliminary structural feature acts as a physical barrier that prevents resin from entering the interface between the rotor core and rotation shaft, thereby preventing axial displacement of the rotor core even when high molding pressure is applied for adequate resin filling.
4Strength
If the rotor core is press-inserted into the rotation shaft to secure high connecting strength, then connection strength is sufficient, but the rotor core may still be displaced during molding pressure application
Solution Approach 1:
The resin prevention portion (protrusion) on the rotation shaft is formed in advance to physically block resin intrusion at the rotor core-rotation shaft interface. This preliminary protective feature ensures that even when high molding pressure is applied, the rotor core remains securely positioned and cannot be displaced axially, thereby maintaining both connection strength and positioning reliability.
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 approach enables the fuel pump to be downsized while maintaining or improving torque and efficiency, and prevents rotor core displacement during resin molding, ensuring reliable assembly and operation.
Implementation Method 1
a motor device for driving a pump portion of a fuel pump by being magnetized using a permanent magnet circumferentially surrounding the motor device
Data Source
AI summary
A fuel pump includes a pump portion for pumping fuel. The fuel pump further includes a magnet having magnetic poles circumferentially alternate with each other. The fuel pump further includes an armature on a radially inside of the magnet. The armature includes a rotor core provided with a coil formed of a wire. The armature is rotatable for driving the pump portion. A commutator, which is in a substantially disc shape, is provided to an axial end of the armature for rectifying electricity supplying to the coil. The rotor core has an axial end having an outer circumferential periphery defining a commutator-side collar portion extending toward the commutator. The coil is formed by winding the wire between an outer circumferential periphery of the commutator and the commutator-side collar portion.