Torsion Spring Pulley Structure for Stable Press-Fit Alignment
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Solution Overview
Problem
The existing pulley structure with a torsion coil spring experiences unstable posture and deformation due to eccentric or inclined axis, leading to poor production quality and reduced productivity during press-fitting, as the torsion coil spring's other end region is not sufficiently constrained, resulting in metal powder generation and wear on contact surfaces.
Innovation Solution
A pulley structure design that includes a constraining surface on the other rotation body, which prevents axis displacement of the torsion coil spring by aligning with the inner circumferential surface of the other end region and the second contact surface, ensuring stable posture and minimizing pressing load concentration during press-fitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the torsion coil spring is twisted in the diameter increasing direction due to relative rotation, then the other end region separates from the other rotation body, but the fixing force becomes smaller and the axis becomes eccentric or inclined
Solution Approach 1:
The other end region of the torsion coil spring is divided into a contact portion that contacts the other rotation body and a non-contact portion that separates during rotation. This segmentation allows the spring to maintain stable posture through the contact portion while enabling free rotation through the separating non-contact portion, resolving the contradiction between stability and rotational freedom.
Solution Approach 2:
A protrusion is introduced as an intermediary element between the torsion coil spring and the other rotation body. The protrusion engages with a corresponding groove to constrain the spring axis, preventing eccentricity and inclination while allowing the spring to twist and the other end region to separate during rotation.
2Adaptability or versatility
If the other end region is not sufficiently constrained, then the torsion coil spring can rotate freely, but metal powder is generated and wear occurs on contact surfaces
Solution Approach 1:
The protrusion-groove mechanism acts as an intermediary constraint that guides the torsion coil spring during rotation. This intermediary structure prevents uncontrolled movement and friction that would generate metal powder, while still allowing the spring to perform its twisting function and maintain rotational freedom between the outer and inner rotation bodies.
Solution Approach 2:
The design changes the constraint parameters by introducing a protrusion with specific dimensions and a corresponding groove. This parameter change enables the system to transition from unconstrained free rotation (causing wear) to controlled rotation with minimal friction, maintaining adaptability while reducing harmful effects.
3Manufacturing precision
If manual adjustments are made during press-fitting, then production quality is maintained, but productivity is reduced
Solution Approach 1:
The protrusion and groove are designed in advance to automatically align and constrain the torsion coil spring during press-fitting. This preliminary design of the constraint mechanism eliminates the need for manual adjustments during the pressing operation, allowing automated high-speed production while maintaining consistent positioning accuracy and production quality.
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 design enhances production quality by maintaining the torsion coil spring's axis alignment, reducing metal powder generation and wear, and increasing productivity by automating the press-fitting process without manual adjustments.
Implementation Method 1
a torsion coil spring which is provided between the outer rotation body and the inner rotation body... When the torsion coil spring is twisted in a diameter increasing direction due to a relative rotation between the outer rotation body and the inner rotation body
Data Source
AI summary
A pulley structure includes: a cylindrical outer rotation body; an inner rotation body; and a torsion coil spring. The torsion coil spring includes: one end region which is in contact with one rotation body; the other end region which is in contact with the other rotation body; and a middle region. The other rotation body includes: a first contact surface; a facing surface; an inclined surface; and a second contact surface. The facing surface includes a constraining surface connected to the inclined surface. The constraining surface is configured to be capable of constraining the other end region of the torsion coil spring before press fitting so as to prevent a displacement of an axis of the torsion coil spring before the press fitting with respect to an axis of the other rotation body.