Electro-Adhesive Isolation Pulley for High-Torque Engine Starting
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Solution Overview
Problem
Existing damped isolation pulleys face stress issues when high torque is required for starting an engine, as the elastomeric isolation spring can be overstressed due to the transmission of rotary power from the motor-generator to the pulley.
Innovation Solution
Incorporating an electro-adhesive clutch that provides an alternate torque path between the pulley and the hub, bypassing the isolation spring, allowing for the transmission of rotary power without overstressing the elastomeric material, utilizing a clutch input member coupled to the pulley and a clutch output member coupled to the hub, with discrete electro-adhesive clutch segments that can be independently energized to vary torque capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rotary power is transmitted from the motor-generator to the pulley through the belt drive system, then the engine can be started, but the elastomeric isolation spring can be overstressed when high torque is required
Solution Approach 1:
The electro-adhesive clutch acts as an intermediary component between the pulley and the hub, providing an alternate torque transmission path that bypasses the isolation spring. When high torque is required for engine starting, the clutch engages to directly couple the pulley to the hub, preventing excessive stress on the elastomeric isolation spring while still enabling the necessary power transmission.
Solution Approach 2:
The system dynamically switches between two torque transmission modes: normal operation through the isolation spring for vibration isolation, and high-torque mode through the electro-adhesive clutch for engine starting. This dynamic reconfiguration allows the system to adapt its stiffness characteristics based on the instantaneous torque requirements, resolving the contradiction between power transmission capability and isolation spring stress.
2Reliability
If the isolation spring is made softer to improve vibration isolation, then the crankshaft isolation is improved, but the torque transmission capability during engine starting is reduced
Solution Approach 1:
The system employs dynamic reconfiguration of the torque transmission path based on operational requirements. During normal operation, the softer isolation spring provides optimal vibration isolation. When engine starting requires high torque, the electro-adhesive clutch engages to create a stiffer alternate transmission path, effectively switching the system's mechanical characteristics to match the instantaneous load requirements.
Solution Approach 2:
The electro-adhesive clutch enables the system to perform multiple functions through a single integrated mechanism: it provides both vibration isolation during normal operation and high-torque transmission during engine starting. This multi-functionality resolves the contradiction by allowing the same system to optimize for different performance criteria at different times.
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 electro-adhesive clutch effectively manages high torque transmission without overstressing the isolation spring, ensuring reliable operation and extended component lifespan by providing a dedicated torque path that reduces strain on the elastomeric material.
Implementation Method 1
The electro-adhesive clutch has a clutch input member that is coupled to the pulley and can be operated to form an alternate torque path between the pulley and the hub
Data Source
AI summary
A damped isolation pulley having a hub, a pulley disposed concentrically about the hub, an isolation spring, an inertia ring and an electro-adhesive clutch. The hub is configured to be mounted to a crankshaft of an internal combustion engine. The isolation spring is formed of an elastomeric material and couples the pulley to the hub. The inertia ring is resiliently coupled to the hub and is rotationally de-coupled from the pulley. The electro-adhesive clutch has a clutch input member that is coupled to the pulley and can be operated to form an alternate torque path between the pulley and the hub that does not include the isolation spring.