Rotation Transmission Device With Homogeneous Thermal Expansion
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Solution Overview
Problem
Conventional rotation transmission devices face issues with magnetic field leakage and misalignment due to different coefficients of linear expansion in materials, leading to unreliable engagement of the two-way clutch and increased complexity and cost.
Innovation Solution
The use of a rotor guide and rotor made of magnetic materials with the same or substantially the same coefficient of linear expansion, featuring circumferentially elongated slits in the rotor guide to minimize magnetic field leakage and ensure reliable coupling without additional preventive means for rotation and axial movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rotor guide is made of non-magnetic material to prevent magnetic field leakage, then magnetic field leakage is reduced, but the rotor and rotor guide have different coefficients of linear expansion causing insufficient interference fit when heated
Solution Approach 1:
The rotor guide is made of magnetic material with the same or substantially the same coefficient of linear expansion as the rotor, ensuring homogeneous thermal expansion behavior. This allows the interference fit to remain effective when both components are heated, while the magnetic material inherently guides and contains the magnetic field, preventing leakage to the outer ring.
Solution Approach 2:
The invention changes the material parameter (coefficient of linear expansion) of the rotor guide to match that of the rotor, and positions slits in the rotor guide to offset from the pressed-in portion. This parameter optimization maintains interference fit reliability under thermal conditions while controlling magnetic field distribution.
2Reliability
If the rotor guide is made of magnetic material with the same coefficient of linear expansion as the rotor, then interference fit reliability is maintained under temperature changes, but magnetic field may leak through to the outer ring
Solution Approach 1:
The rotor guide is segmented by forming slits that divide the magnetic material into separate regions. These slits are positioned to offset from the pressed-in portion of the rotor, creating magnetic field pathways that contain the flux within the rotor guide while preventing it from leaking through to the outer ring, thus resolving the magnetic field leakage issue while maintaining the homogeneous material composition.
3Stability of the object's composition
If additional means are provided to prevent relative rotation and axial movement between rotor and rotor guide, then component stability is improved, but device complexity and cost increase
Solution Approach 1:
The invention optimizes the geometric parameters of the interference fit and the positioning of slits in the rotor guide to provide sufficient stability without additional fastening means. The slits are strategically positioned to offset from the pressed-in portion, and the interference fit dimensions are designed to maintain both rotational and axial stability under operating conditions, eliminating the need for protrusions, cutouts, snap rings, or grooves.
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 solution enhances the magnetic attraction force, simplifies the structure, and reduces costs by ensuring reliable engagement of the two-way clutch and stable coupling of components, even under temperature changes.
Implementation Method 1
an electromagnet axially facing the rotor to attract the armature to the rotor when energized
Implementation Method 2
when the rotor and the rotor guide are heated and expanded, there will not be enough interference left for the rotor to remain secured to the rotor guide
Data Source
AI summary
A rotation transmission device includes inner and outer rings, a two-way clutch mounted between the outer and inner rings, and an electromagnetic clutch mounted adjacent to the two-way clutch. The electromagnetic clutch includes a rotor guide pressed onto the outer ring at its open end and a rotor pressed into the rotor guide. The rotor guide is made of a magnetic material having the same or substantially the same coefficient of linear expansion as the material of the rotor. Thus, even when the rotor guide and the rotor are heated and expanded, the interference between the rotor and the rotor guide remains substantially constant. Therefore, the rotor and the rotor guide can be reliably coupled together with a simple structure and at a low cost.