Compact Electric Machine for Vehicle Propulsion
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Solution Overview
Problem
Existing vehicle propulsion systems for heavy trucks and buses face challenges with increased current-weight ratio due to smaller starter motors and generators, leading to reduced performance and a higher risk of high temperatures and fire hazards, as they require significant space and separate belts for operation.
Innovation Solution
A compact electric machine design where the stator is rigidly connected to the vehicle frame with windings and the rotor connected to the flywheel, featuring multiple air gaps created by projecting members and recess portions to enhance torque transfer, and a planetary gear system to adjust rotation speeds, allowing for increased torque and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the starter motor and generator are made smaller to reduce weight, then the current-weight ratio increases, but the quality reduces and the risk of high temperatures and fire hazards increases
Solution Approach 1:
The patent combines the starter motor and generator into a single electric machine with dual functionality. The machine operates as a starter motor during engine startup and as a generator during engine operation, eliminating the need for separate components and reducing overall weight while maintaining reliability through integrated design and thermal management.
2Weight of moving object
If the starter motor and generator are made smaller, then weight is reduced, but the space required remains considerable due to separate belt operation
Solution Approach 1:
The electric machine is designed with a single drive mechanism that powers both motor and generator functions, eliminating the need for separate belts. The machine is integrated into the engine assembly, utilizing existing space and mounting structures, thereby reducing the overall space footprint while maintaining weight reduction benefits.
3Force
If projecting members are added to create air gaps, then torque transfer increases, but the device complexity increases
Solution Approach 1:
The projecting members are strategically positioned at specific locations on the rotor and stator to create localized air gaps where magnetic flux needs enhancement. This targeted approach increases torque transfer efficiency without requiring complex modifications throughout the entire machine structure, maintaining design simplicity while achieving the desired force improvement.
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 solution results in a more compact and efficient propulsion system with increased torque transfer, reducing space requirements and minimizing the risk of high temperatures and fire hazards while maintaining performance.
Implementation Method 1
a stator rigidly connected to a vehicle frame fixed part and provided with windings connected to the arrangement for being fed with electric energy from the arrangement in motor operation of the electric machine
Implementation Method 2
feeding electric energy to the arrangement in generator operation of the electric machine
Implementation Method 3
at least one of the stator and the rotor has a member projecting into a recess portion of the other so as to form air gaps for magnetic flux between the rotor and the stator
Data Source
AI summary
A vehicle propulsion system comprises a combustion engine with a flywheel secured to a crank shaft of the engine. A starter motor and a generator are combined in one electric machine having a stator rigidly connected to a vehicle frame fixed part and provided with windings connected to an arrangement storing electric energy for being fed with electric energy from the arrangement in motor operation of the electric machine and feeding electric energy to the arrangement in generator operation of the electric machine and a rotor connected to the flywheel so as to make the rotor and flywheel rotating in dependence of each other. At least one of the stator and rotor has a member projecting into a recess portion of the other so as to form air gaps for magnetic flux between the rotor and the stator on both sides of the projecting member.