Coaxial Motor Unit with Nested Fixing Members
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Solution Overview
Problem
Existing electric motors in hybrid and electric vehicles are large due to protruding bolts, which hinder miniaturization efforts.
Innovation Solution
A motor unit design featuring coaxially disposed rotating electric machines with a surface-matching fixing portion and orthogonal fixing portion, utilizing a single drive device that integrates with the motor units' peripheral surfaces, reducing the need for external protrusions and allowing for compact assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bolt is inserted through two stators along the axes to couple them, then the stators are securely connected, but the bolt protrudes toward the outside of the axial end portion causing the electric motor to increase in size
Solution Approach 1:
The fixing member is nested within the axial end portions of the stators. The first fixing member is received in a groove formed in the axial end portion of the first stator, and the second fixing member is received in a groove formed in the axial end portion of the second stator. This nesting arrangement allows the fixing members to be concealed within the stator structures rather than protruding outward, thereby securing the connection between stators while preventing an increase in the overall axial length of the electric motor.
Solution Approach 2:
Grooves are introduced as intermediary structures to accommodate the fixing members. These grooves are formed in the axial end portions of the stators and serve as receptacles that hold the fixing members in place. The grooves act as mediators between the fixing members and the stator bodies, allowing the fixing members to perform their connection function while being concealed within the stator structures, thus resolving the contradiction between secure connection and compact dimensions.
2Stability of the object's composition
If two stators are coaxially connected with bearings in between, then the motor structure is stable, but the overall motor size increases
Solution Approach 1:
The fixing members and grooves are merged into the overall stator structure. The grooves are formed as integral features of the stator bodies, and the fixing members are integrated into these grooves. This merging eliminates the need for separate, protruding connection components and allows the connection structure to be compactly incorporated within the existing motor volume, maintaining structural stability without increasing overall size.
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 effectively minimizes the motor unit's size by integrating the drive device and fixing members within the motor unit's structure, enhancing assembly workability and reducing overall dimensions.
Implementation Method 1
a surface-matching fixing portion which is fixed by a fixing member while an axial end surface of the first casing comes into contact with an axial end surface of the second casing
Implementation Method 2
when a current is supplied to a coil, a magnetic field is formed in a stator core and magnetic attraction and repulsion are generated between a rotor and the stator core. Accordingly, the rotor rotates with respect to the stator
Data Source
AI summary
A motor unit includes: a first rotating electric machine which includes a cylindrical first stator, a first rotor disposed coaxially with the first stator, a first shaft disposed coaxially with the first rotor, and a cylindrical first casing accommodating the first stator and the first rotor; a second rotating electric machine which includes a cylindrical second stator, a second rotor disposed coaxially with the second stator, a second shaft disposed coaxially with the second rotor, and a cylindrical second casing accommodating the second stator and the second rotor; a single drive device which is integrally fixed across a peripheral surface in a diameter direction of the first rotor in the first casing and a peripheral surface in a diameter direction of the second rotor in the second casing; and a surface-matching fixing portion which is fixed by a fixing member while an axial end surface of the first casing comes into contact with an axial end surface of the second casing.