Wrap Spring Clutch Torque Transfer for Low-Impact Accessory Shafts
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Solution Overview
Problem
Existing clutch systems for vehicle accessory shafts, such as air conditioning compressors, face challenges in balancing low power draw with reduced impact loads on components, as some require high power for torque and others suffer from high impact loads leading to potential component failure.
Innovation Solution
A clutch system incorporating a rotary input member, a rotary output member, an armature, and a wrap spring clutch with specific torque transmission characteristics, allowing the armature to move between engagement and disengagement positions, and the wrap spring clutch to transition between coil engagement and disengagement positions, enabling controlled torque transfer with adjustable stiffness to manage power consumption and reduce component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a plate clutch is used to drive the accessory shaft, then sufficient torque can be provided, but a significant amount of power is required to operate the clutch
Solution Approach 1:
The clutch system is segmented into two distinct clutch mechanisms: a friction clutch for engagement/disengagement control and a wrap spring clutch for torque transmission. This segmentation allows each component to perform its specialized function efficiently, with the wrap spring clutch providing torque with lower power draw compared to traditional plate clutches that must continuously engage friction surfaces.
Solution Approach 2:
The wrap spring clutch acts as an intermediary between the friction clutch and the accessory shaft. It receives torque from the friction clutch and transmits it to the accessory shaft, enabling torque transmission with reduced power consumption by utilizing elastic deformation of the wrap spring rather than continuous friction engagement.
2Use of energy by moving object
If a low power clutch system is used, then power consumption is reduced, but high impact loads are imposed on accessory components
Solution Approach 1:
The wrap spring clutch is designed to engage gradually and cushion the engagement process, preventing sudden impact loads on accessory components. The elastic properties of the wrap spring allow it to absorb and dissipate shock during engagement, protecting components from high impact forces while maintaining low overall power consumption.
Solution Approach 2:
The wrap spring clutch changes its stiffness parameter during engagement, being more compliant during initial engagement to reduce impact loads and becoming stiffer as it fully engages to transmit torque efficiently. This dynamic parameter change allows the system to maintain low power draw while protecting components from damaging impact forces.
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 system achieves low power consumption while minimizing component stress, allowing for efficient operation of accessory shafts by initiating rotation with a lower torque and transitioning to higher torque as needed, thereby reducing the risk of mechanical failure.
Implementation Method 1
In the armature engagement position, the armature is frictionally rotationally engaged with the rotary input member
Implementation Method 2
The wrap spring clutch has a first helical end, a second helical end, and a plurality of coils therebetween
Data Source
AI summary
A clutch system includes a rotary input member, a wrap spring clutch and a rotary output member. The wrap spring clutch has a first end, a second end, and a plurality of coils. The stiffness of the wrap spring clutch is selected such that, when transmitting less than a selected coil engagement torque, the clutch system transmits torque helically from the rotary input member, to the second end, helically through the wrap spring clutch to the first end, and into the rotary output member. When transmitting more than the selected coil engagement torque, the clutch system transmits torque in parallel from the rotary input member, to the second end, helically through the wrap spring clutch to the first end, and into the rotary output member, and from the rotary input member through the coil engagement surface, to the first end, and into the rotary output member.