Wrap Spring One-Way Clutch Isolator Decoupler for Compact Alternators
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Solution Overview
Problem
Current alternator isolating decoupler devices have a large overall diameter due to the need for various components, which is not suitable for smaller automotive engines with increasing fuel efficiency requirements, and there is a need for a mechanism to reduce frictional engagement between the wrap spring one-way clutch and the shaft during high torque conditions.
Innovation Solution
An isolator decoupler design featuring a pulley temporarily engagable with the end of the wrap spring one-way clutch in the unwinding direction, which reduces frictional engagement by releasing tension in the wrap spring, allowing the clutch to slip and reducing torque transmission to the shaft, thereby preventing excessive stress on the torsion spring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional components (isolating spring, one way clutch, bearing(s), pulley) are used in alternator isolating decoupler devices, then the device can maintain required functionality, but the overall diameter becomes too large for smaller automotive engines
Solution Approach 1:
The patent combines the isolating spring and one-way clutch into a single integrated wrap spring one-way clutch component. This merging eliminates the need for separate isolating spring and one-way clutch components, reducing the overall device diameter while maintaining the isolation functionality and one-way clutch operation.
Solution Approach 2:
The wrap spring one-way clutch serves multiple functions simultaneously: it provides isolation through torsional flexibility, acts as a one-way clutch to prevent reverse rotation, and transmits torque during normal operation. This multi-functionality reduces the number of separate components needed, thereby reducing device diameter.
2Reliability
If the wrap spring one-way clutch maintains constant frictional engagement with the shaft, then torque transmission is consistent, but excessive stress and noise occur during high torque conditions
Solution Approach 1:
The patent makes the frictional engagement dynamic rather than constant. During high torque conditions, the wrap spring can unwind temporarily from the shaft, reducing frictional engagement and allowing the clutch to slip. This dynamic adjustment prevents excessive stress and noise while maintaining torque transmission stability during normal operation.
Solution Approach 2:
The frictional engagement parameter changes based on operating conditions. Under normal torque, the wrap spring maintains frictional engagement for stable torque transmission. Under high torque conditions, the wrap spring unwinds, changing the engagement state to reduce stress and noise, thereby adapting the system response to varying load conditions.
3Use of energy by moving object
If the pulley diameter is reduced to meet fuel efficiency requirements, then fuel efficiency improves, but the device may not accommodate all necessary components
Solution Approach 1:
By merging the isolating spring and one-way clutch into a single wrap spring one-way clutch component, the patent reduces the number of separate parts that need to be accommodated within the pulley assembly. This integration enables a smaller pulley diameter while maintaining all necessary functionality for isolation and torque transmission.
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 design allows for a smaller device diameter while maintaining functionality, effectively managing high torque conditions by reducing the torque transmitted to the torsion spring, preventing premature failure and noise, and ensuring proper component contact during normal operation.
Implementation Method 1
The wrap spring one way clutch is frictionally engaged to the shaft such that the wrap spring one way clutch transmits torque to the shaft
Implementation Method 2
an isolating spring, one way clutch, bearing(s), a pulley
Data Source
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AI summary
An isolator decoupler comprising a pulley, a shaft, the pulley journalled to the shaft on a low friction bushing, a spring carrier disposed within the pulley, a torsion spring coupled between the pulley and the spring carrier, a wrap spring one way clutch wrapped about the shaft and having a frictional engagement' therewith, the wrap spring one way clutch coupled to the spring carrier, the wrap spring one way clutch is disposed radially inward of the torsion spring, and the pulley temporarily engagable with an end of the wrap spring one way clutch in an unwinding direction whereby a temporary contact between the wrap spring one way clutch end and the pulley will temporarily diminish the frictional engagement of the wrap spring one way clutch with the shaft.