Nested Spring Assembly Isolator Retainer Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing isolators between the engine crankshaft and endless drive members, such as belt systems, suffer from noise issues due to the sliding movement of inner springs within central apertures, particularly in engines with specific cylinder counts, as the inner springs are often shorter than the outer springs.
Innovation Solution
A spring assembly comprising first and second helical compression springs, a retainer, and a spring housing, where the second spring is nested within the first and the retainer's post prevents sliding by engaging the inner spring's central aperture, ensuring direct force transfer through the spring housing without retainer-mediated movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the inner spring is positioned in the central aperture of the outer spring, then the isolator structure is compact and effective for torque transfer, but sliding movement occurs between the inner spring and aperture causing noise
Solution Approach 1:
A retainer component is introduced as an intermediary between the inner spring and the outer spring's central aperture. The retainer includes a base portion that engages the inner spring and a circumferential flange that contacts the outer spring, preventing direct sliding contact between the inner spring and aperture while maintaining the nested spring configuration for torque transfer.
2Length of moving object
If the inner spring is shorter than the outer spring, then the nested spring configuration is achieved, but sliding movement of the inner spring in the central aperture occurs
Solution Approach 1:
The retainer acts as a mediator that prevents sliding movement of the shorter inner spring within the outer spring's central aperture. The retainer's base portion engages the inner spring while its circumferential flange contacts the outer spring, eliminating direct contact between the inner spring and aperture that would cause noise.
3Reliability
If the retainer mediates movement between springs, then the springs are retained in position, but force transfer efficiency is reduced
Solution Approach 1:
The retainer is designed as a low-friction intermediary that maintains spring positions while minimizing interference with force transfer. The circumferential flange contacts the outer spring at specific engagement points, and the base portion engages the inner spring, allowing torque transfer through the nested springs while preventing unwanted sliding movements that would cause noise and energy loss.
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 configuration effectively reduces noise by stabilizing the inner spring's position, enhancing torque transfer efficiency and minimizing vibration-induced noise in engine systems.
Implementation Method 1
first and second helical compression springs
Data Source
Figure 1
Figure 1a
Figure 2
AI summary
In an aspect, a spring assembly is provided for an isolator, and includes first and second helical compression springs, a retainer and a spring housing. The first helical compression spring has a central aperture and has a first end and a second end. The second helical compression spring having a central aperture and having a first end and a second end, wherein the second spring is coaxial with and nested within the first spring. The retainer has a base and a post that extends from the base into the central aperture at the first end of the second helical spring. The spring housing that has an interior space in which the first and second springs are positioned, and further includes a base-engaging aperture that holds the base of the retainer. The spring housing includes a drive wall that is engaged with the first ends of the first and second springs.