Magnetic Pulley Assist Coupling for Hybrid Automotive Accessories
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Solution Overview
Problem
Automotive accessories driven mechanically by an engine face limitations such as inability to operate when the engine is not running and dependent rotational speed, while electrically driven accessories face challenges with power management due to 12V DC limitations, making it difficult to achieve high power outputs without overheating.
Innovation Solution
An electrically and mechanically driven automotive accessory that incorporates a pulley assist mechanism using an electromagnet and circumferentially spaced teeth to create a secondary torque flow path, allowing for higher rotational speeds and power output while reducing electric current demand, enabling independent control of rotational speed and operation without the engine running.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electric motor is used to drive the accessory independently of engine speed, then the accessory can operate when the engine is not running and rotational speed can be controlled independently, but the power output is limited due to 12V DC heat management constraints
Solution Approach 1:
The patent combines mechanical drive and electrical drive systems into a single hybrid accessory drive unit. The mechanically driven pulley and electric motor share a common shaft and rotor assembly, allowing the accessory to receive power from either source or both simultaneously, thereby achieving independent operation capability while overcoming 12V power limitations through mechanical torque supplementation
Solution Approach 2:
The accessory drive unit is designed to accept power from multiple sources (engine belt drive and electric motor) and operate in multiple modes (mechanically driven only, electrically driven only, or hybrid operation). The electromagnet assembly can function both as a clutch mechanism and as a torque transfer element, providing multi-functional capability that enables versatile operation across different driving conditions
2Power
If a mechanically driven accessory is used, then high power output can be achieved, but the accessory cannot operate when the engine is not running and rotational speed is dependent on engine speed
Solution Approach 1:
The clutch assembly incorporates an electromagnet that can dynamically engage and disengage the magnetic coupling between the pulley and rotor body based on operational requirements. This dynamic control allows the system to switch between mechanically driven mode (for high power when engine is running) and electrically driven mode (for independent operation when engine is not running), providing adaptability while maintaining high power capability
3Loss of energy
If the electric motor is downsized to reduce heat generation, then power management is improved, but the power output capability is reduced
Solution Approach 1:
By merging mechanical torque from the pulley with electrical torque from the downsized motor, the system achieves high total power output without requiring a large electric motor. The mechanical drive handles the bulk of power transmission while the smaller electric motor provides supplemental torque and control, reducing heat generation while maintaining adequate power output capability
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
Enables the generation of 1.7-1.8 kW of pumping power, reduces electric current requirements, and allows for downsizing of the electric motor, while providing independent control over rotational speed and mechanical drag, overcoming the limitations of both mechanically and electrically driven accessories.
Implementation Method 1
The pulley assist mechanism includes an electromagnet, a plurality of circumferentially spaced teeth that are nested with a conductive body, and a rotor body that is fixedly mounted to the shaft. When the electromagnet is activated, a magnetic coupling is formed that creates a secondary torque flow path between the pulley and the rotor body due to the magnetic field generated in the pulley, the circumferentially spaced teeth, and the rotor body by the electromagnet.
Implementation Method 2
a magnetic coupling is formed that creates a secondary torque flow path between the pulley and the rotor body due to the magnetic field generated in the pulley, the circumferentially spaced teeth, and the rotor body by the electromagnet
Data Source
AI summary
An electrically and mechanically driven automotive accessory including a housing, an electric motor, a pulley, and a pulley assist mechanism. The electric motor comprises a stator assembly that is mounted to the housing and a rotating assembly that is mounted to a shaft. The electric motor creates a primary torque flow path that drives rotation of the rotating assembly relative to the stator assembly. The pulley is rotatable relative to the shaft and the rotating assembly. The pulley assist mechanism includes a plurality of circumferentially spaced teeth nested with a conductive body, a rotor body fixedly mounted to the shaft, and an electromagnet that is configured to induce a magnetic field between the circumferentially spaced teeth, the rotor body, and the pulley, which creates a secondary torque flow path between the pulley and the rotor body.