Axial Torsion Spring Isolating Decoupler Pulley Diameter
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Solution Overview
Problem
Existing isolating decouplers face a size limitation due to the diameter of the torsion spring, which is typically larger than the belt bearing surface, restricting the miniaturization of automotive engine components and increasing the overall diameter of the device.
Innovation Solution
The isolating decoupler design positions the torsion spring axially adjacent to the belt bearing surface, allowing a larger diameter for the spring without increasing the pulley diameter, and uses a cylindrical form with a uniform diameter along its length, enabling smaller overall device dimensions and improved packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the torsion spring is disposed radially between the shaft and the pulley, then the spring can be positioned within the pulley structure, but the pulley diameter increases depending on the spring rate
Solution Approach 1:
The torsion spring is repositioned from a radial arrangement (between shaft and pulley) to an axial arrangement (adjacent to the belt bearing surface). This dimensional change allows the spring to extend axially rather than radially, enabling the spring diameter to exceed the pulley diameter without increasing the pulley's radial dimensions.
Solution Approach 2:
The spring retainer is designed with a receptacle that prepositions the torsion spring in the axial location before operation. This preliminary positioning ensures the spring is correctly placed adjacent to the belt bearing surface, maintaining the desired axial configuration and preventing radial expansion that would increase pulley diameter.
2Reliability
If the torsion spring diameter is increased to accommodate higher spring rates, then the isolation performance improves, but the overall device diameter increases
Solution Approach 1:
The spring is oriented axially adjacent to the belt bearing surface rather than radially, allowing the spring's diameter to extend beyond the pulley diameter. This repositioning enables higher spring rates (improving isolation performance) without increasing the device's radial dimensions.
Solution Approach 2:
The spring rate can be varied independently of the pulley diameter by changing the spring's axial position and dimensions. This allows optimization of isolation performance through spring parameter selection without being constrained by the pulley size, as the spring now operates in an axial rather than radial space.
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 pulley diameter over balls, reduced overall device diameter, and greater control over design and operating characteristics, while accommodating higher spring rates and longer torsion springs, effectively addressing the size constraints of existing decouplers.
Implementation Method 1
a torsion spring (3) axially adjacent to the belt bearing surface (41) of the pulley (4)
Data Source
Figure 1
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Figure 3
AI summary
An isolating decoupler comprising a shaft, a pulley journalled to the shaft and having a belt bearing surface, the belt bearing surface having a diameter over balls not greater than 2A, a one-way clutch mounted to the shaft, a clutch carrier mounted to the one-way clutch, a torsion spring engaged between the clutch carrier and the pulley, the torsion spring loadable in the unwinding direction, the torsion spring having a diameter not less than 2B, and the torsion spring diameter 2B is greater than the belt bearing surface diameter over balls 2A.