Vibration Isolator Bushing with Composite Hardness for Shifter Control
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Solution Overview
Problem
Manual transmission shifters face challenges in isolating vibrations while minimizing rotation of the shifter housing, leading to noise and vibration issues, particularly when using a single reaction arm with stiffer bushings, which increases packaging space, weight, and cost, and when using dual reaction arms with softer bushings, which compromises control over gear shifting.
Innovation Solution
A bushing system comprising an inner sleeve and a barrel with different hardness levels, combined with a rigid cup and flange, limits the range of longitudinal rotation of the reaction arm by compressing the flange against the outer ring surfaces, allowing for vibration attenuation while maintaining control over the shifter housing orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single reaction arm with a stiffer bushing is used, then rotational control of the shifter housing is improved, but noise and vibration transmission increases
Solution Approach 1:
The bushing is designed with non-uniform hardness distribution: the inner sleeve has higher hardness (50-60 durometer) for rotational control, while the outer barrel has lower hardness (30-40 durometer) for vibration attenuation. This local quality differentiation allows the single bushing to simultaneously provide both rotational precision and vibration isolation.
Solution Approach 2:
The bushing combines two materials with different hardness properties into a single composite structure. The inner sleeve material provides stiffness for rotational control, while the outer barrel material provides compliance for vibration damping, creating a composite bushing that resolves the contradiction between rotational precision and vibration isolation.
2Object-affected harmful factors
If dual reaction arms with softer bushings are used, then noise and vibration isolation is improved, but packaging space and weight increase
Solution Approach 1:
The patent merges the functions of two separate reaction arms into a single reaction arm. The single arm incorporates a composite bushing that combines the vibration isolation properties of softer materials with the rotational control properties of stiffer materials, eliminating the need for dual arms while maintaining both vibration isolation and rotational precision.
Solution Approach 2:
The single reaction arm with composite bushing performs multiple functions simultaneously: it provides rotational control through the harder inner sleeve, vibration isolation through the softer outer barrel, and structural support. This multi-functionality replaces the need for separate dual reaction arm assemblies, reducing packaging space and weight.
3Weight of moving object
If a single reaction arm with softer bushing is used, then packaging space and weight are reduced, but rotational control and gear shifting precision deteriorate
Solution Approach 1:
The composite bushing implements local quality by concentrating the harder material (inner sleeve) in the region that contacts the reaction arm to provide rotational control, while the softer material (outer barrel) handles vibration isolation. This localized hardness distribution maintains gear shifting precision with a single lightweight arm.
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 bushing system effectively isolates vibrations and limits unwanted rotation, reducing noise and vibration transmission while maintaining precise gear shifting, thus optimizing the balance between vibration isolation and rotational control without increasing packaging space or weight.
Implementation Method 1
a barrel radially disposed over the inner sleeve and having a second hardness lower than the first hardness to attenuate vibrations
Data Source
AI summary
A manual transmission shifter includes a reaction arm mounting the shifter to a transmission via a bushing. The bushing includes a resilient member having a tubular section lining a mounting hole in the arm and having a flange extending around the hole. The bushing includes a rigid cup member having an inner sleeve disposed within the tubular section and having a cup rim defining a recess between the inner sleeve and cup rim with a predetermined depth. The flange has a thickness greater than the predetermined depth and is inserted in the recess to create an open gap between the cup rim and the arm. A fastener extends through the inner sleeve to attach the cup member to a transmission bracket. The resilient member attenuates vibrations through the bushing. The arm is provided with a limited range of longitudinal rotation by contact of the arm with the cup rim.