Brushless Alternator Yoke Joint Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Brushless alternators face challenges with high magnetic resistance due to stress concentration at joints, leading to reduced output current and efficiency, and are limited by weight and heat/vibration resistance requirements.
Innovation Solution
The design features a yoke with a thin and thick portion integrally formed in one piece, with the joint between the yoke and holding member located away from the magnetic circuit, reducing magnetic resistance and enhancing output power and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If spot-welding is used to join the step portion of the second yoke to the plate, then the structural strength is improved, but the magnetic resistance increases due to stress concentration at the joint
Solution Approach 1:
The yoke is divided into a main body portion and a separate plate portion that are joined together. This segmentation allows the joint to be positioned away from the magnetic circuit path, reducing magnetic resistance while maintaining structural strength through proper joining methods.
Solution Approach 2:
A holding member is introduced as an intermediary component between the yoke and the plate. This holding member facilitates the connection while allowing the joint to be located at a position that minimizes interference with the magnetic flux path, thereby reducing magnetic resistance.
2Loss of energy
If gluing or screwing is used to fix the step portion of the second yoke and the plate, then the magnetic resistance is reduced, but the weight support capability and heat/vibration resistance are insufficient
Solution Approach 1:
The joint position is strategically located at a curved or non-critical area away from the magnetic circuit path. This positioning reduces magnetic resistance while the overall structural design ensures that the joint can still support weight and resist heat and vibration through proper geometric configuration.
3Power
If the radial thickness of the cylindrical portion of the plate is increased to improve the magnetic circuit, then the output is enhanced, but the field current decreases due to the comprehensive trade-off
Solution Approach 1:
Instead of solely increasing the radial thickness of the plate to improve the magnetic circuit, the invention shifts the optimization to a different dimension by repositioning the joint location. This allows the magnetic circuit to be improved through better flux path configuration rather than simply increasing material thickness, thereby avoiding the negative effect on field current.
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 configuration increases output current and efficiency while maintaining heat resistance and longevity, allowing for a more compact and durable brushless alternator suitable for vehicular applications.
Implementation Method 1
a field coil wound around the bobbin, for producing magnetic flux
Data Source
AI summary
A brushless alternator of the present invention includes: a yoke whose inner circumferential surface is radially opposite via an air gap to a rotor revolvably supported by brackets; a stator supported by the brackets, for forming a magnetic circuit along with the rotor and the yoke; a bobbin for engaging with the outer circumferential surface of a thin portion of the yoke; a field coil wound around the bobbin, for producing magnetic flux; and a plate joined to the thin portion, for axially holding the bobbin; wherein the thin portion of the yoke and the other portion thereof are integrally formed in one piece using a single member.