Variable Speed Magnetic Gear Alternator Design
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Solution Overview
Problem
Conventional vehicle alternators experience high speeds at maximum engine speeds, leading to inefficiency and increased wear, while attempts to reduce speed through mechanical or magnetic gear systems introduce complexity, weight, and parasitic losses, and existing variable speed magnetic gears are cumbersome and heavy.
Innovation Solution
A generator system incorporating a magnetic gear with a stationary member of electromagnets, a moveable member of magnets, and a core member between them, allowing for variable gear ratios without physically moving the stationary member, decoupling output speed from input speed and integrating the magnetic gear with the generator for a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the alternator is directly driven by the engine using a fixed pulley ratio to ensure sufficient generating capacity at idle, then the alternator can meet electrical demand at low engine speeds, but the alternator speed becomes excessively high at maximum engine speeds, leading to increased wear and reduced reliability
Solution Approach 1:
The patent applies a variable speed magnetic gear that dynamically adjusts the gear ratio between engine and alternator based on operating conditions. At idle, a higher ratio (e.g., 3:1) ensures sufficient alternator speed for electrical generation, while at maximum engine speed, the ratio reduces (e.g., 1:1 or 0.5:1) to limit alternator speed. This dynamic adjustment resolves the contradiction by allowing the system to adapt the transmission ratio in real-time, maintaining reliability across the full engine speed range without subjecting the alternator to excessive speeds.
2Speed
If the size of the alternator armature is increased to reduce maximum alternator speed, then the alternator can operate at lower speeds with reduced wear, but the vehicle weight increases, contradicting emissions reduction goals
Solution Approach 1:
Rather than statically increasing armature size, the patent employs a dynamic variable speed magnetic gear system that maintains a compact alternator design while adjusting the transmission ratio based on engine speed. This allows the alternator to operate at optimized speeds across all conditions without requiring a larger, heavier armature, thus resolving the contradiction between speed reduction and weight reduction.
3Speed
If a mechanical gearbox with two selectable ratios is used between the alternator and pulley, then the alternator speed can be controlled at different engine speeds, but the system complexity increases and there is a changeover time when generation drops significantly
Solution Approach 1:
The patent replaces the mechanical gearbox with a variable speed magnetic gear system that uses magnetic coupling and electromagnetic fields to achieve continuous variable ratio transmission. This eliminates mechanical gears, shafts, and clutch mechanisms, thereby reducing complexity while enabling smooth, continuous adjustment of the alternator speed ratio without interruption or significant generation drop.
Solution Approach 2:
The magnetic gear system provides continuous dynamic adjustment of the transmission ratio rather than discrete fixed ratios. This allows seamless adaptation to varying engine speeds and electrical loads, maintaining power generation continuity and eliminating the changeover problems associated with mechanical gear shifting.
4Speed
If a variable speed magnetic gear with an external means for driving the outer rotor is used, then the gear ratio can be varied to control alternator speed, but the system becomes complex, large, and heavy
Solution Approach 1:
The patent integrates the variable speed magnetic gear functionality directly into the alternator assembly, where the magnetic gear components share the same structural elements and magnetic circuits as the generator. This multi-functional integration eliminates the need for separate external driving mechanisms, reducing complexity, size, and weight while maintaining variable ratio capability.
Solution Approach 2:
The patent merges the magnetic gear system with the alternator by using the same stator and rotor structures for both functions. The electromagnets and magnetic circuits serve dual purposes: generating electrical power and providing variable speed transmission. This consolidation resolves the contradiction by achieving variable gear ratio control without adding separate complex external driving systems.
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 reduces the maximum speed of the alternator, maintains generating capacity, and simplifies the system by eliminating the need for external means to move the stationary member, providing a compact and efficient power generation solution that matches electrical demand across varying engine speeds.
Implementation Method 1
a stationary member comprising a set of electromagnets; a first moveable member comprising a set of magnets; and a second moveable member disposed between the first moveable member and the stationary member
Implementation Method 2
the first moveable member comprises an armature of the generator, the armature being arranged to induce an electrical current in a set of generator windings disposed around the stator
Data Source
AI summary
A generator comprising a magnetic gear, the magnetic gear comprising a stationary member comprising a set of electromagnets, a first moveable member comprising a set of magnets, and a second moveable member disposed between the first moveable member and the stationary member. The second moveable member comprises a set of core members. The first and second moveable members are magnetically coupled to define a gear ratio therebetween and the electromagnets are operable to control the gear ratio. The stationary member comprises a stator of the generator and the first moveable member comprises an armature of the generator, wherein the armature is arranged to induce an electrical current in a set of generator windings disposed around the stator. The second moveable member comprises an input means arranged to receive a drive force. The gear ratio is variable, such that a variable output speed may be produced for a given input speed. In this way, the electrical output of the generator is decoupled from the input speed, so as to provide sufficient power for a range of input speeds.