Brushless Starter Motor Thermal Management and Control
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Solution Overview
Problem
Internal combustion engines face challenges in efficiently starting and restarting, particularly in hybrid electric vehicles, where rapid and smooth engine reactivation is needed to minimize fuel consumption and reduce noise, vibration, and harshness (NVH) during engine restarts.
Innovation Solution
A starter assembly incorporating a multi-phase brushless electric motor with a stator, rotor, and electronic commutator assembly, including a sensing circuit, control electronics, power electronics, and a heat sink, which uses a rotor position target and thermally conductive insulators to optimize motor performance and thermal management, enabling precise control and efficient cranking torque delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional brushed motor is used for engine starting, then the structure is simple and cost is low, but the reliability is reduced due to brush wear and maintenance requirements
Solution Approach 1:
The patent replaces the mechanical brush-commutator system with an electronic commutator assembly that uses sensors and electronic switches. This substitution eliminates the mechanical wear components (brushes) while providing more reliable operation, directly resolving the contradiction between reliability and structural complexity.
2Use of energy by moving object
If engine restart is delayed to minimize fuel consumption, then fuel efficiency improves, but the response time and driver convenience deteriorate
Solution Approach 1:
The patent implements dynamic engine restart capability where the control system continuously monitors operating conditions and executes restart when optimal conditions are detected. The electronic commutator enables rapid motor response, allowing the system to balance fuel efficiency with quick restart response based on real-time conditions.
Solution Approach 2:
The sensing circuit provides continuous feedback on rotor position and motor operating conditions, enabling the control system to optimize restart timing and duration. This feedback mechanism allows the system to minimize fuel consumption while maintaining rapid response capability when needed.
3Productivity
If high cranking torque is delivered rapidly for quick engine start, then productivity improves, but thermal load on motor increases reducing component lifespan
Solution Approach 1:
The patent introduces a thermally conductive electrical insulator as an intermediary component between the power electronics subassembly and heat sink. This intermediary enables efficient thermal transfer while maintaining electrical isolation, allowing high cranking torque delivery without excessive thermal accumulation in sensitive electronic components.
Solution Approach 2:
The brushless motor design with electronic commutation replaces the traditional brushed motor, eliminating brush arcing and contact resistance that generate heat. This substitution reduces thermal load on commutation components while maintaining high torque delivery capability.
4Object-affected harmful factors
If NVH reduction measures are implemented during engine restart, then comfort improves, but the complexity of control systems increases
Solution Approach 1:
The sensing circuit provides real-time feedback on rotor position and motor operation, enabling the control system to implement NVH reduction strategies such as optimized commutation timing and current waveform control. This feedback-based control reduces noise and vibration while maintaining manageable system complexity through sensor-driven adjustments.
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 provides rapid, smooth, and efficient engine starting with reduced NVH, improving fuel efficiency and extending motor lifespan by leveraging the precision control and thermal management of the brushless electric motor system.
Implementation Method 1
The power electronics subassembly is thermally coupled to the heat sink
Implementation Method 2
A rotor position target is disposed on the second end of the rotatable shaft, wherein the sensing circuit is disposed to monitor the rotor position target
Implementation Method 3
A starter assembly for an internal combustion engine includes a multi-phase brushless electric motor
Data Source
AI summary
A starter assembly includes a multi-phase brushless electric motor including a stator, a rotor disposed on a rotatable shaft, and a motor endcap disposed at a first end of the stator. An electronic commutator assembly includes a sensing circuit, a control electronics subassembly, a power electronics subassembly and a heat sink. The sensing circuit is disposed adjacent to the second end of the rotatable shaft. The control electronics subassembly, the power electronics subassembly and the heat sink are disposed on disk-shaped devices arranged in a stacked configuration orthogonal to the axis defined by the rotatable shaft. The control electronics subassembly is disposed adjacent to the sensing circuit, and the power electronics subassembly is disposed adjacent to the control electronics subassembly. The control electronics subassembly is interposed between the power electronics subassembly and the sensing circuit. The heat sink is disposed adjacent to the power electronics subassembly.