Shift Lever Resin Molding for Detent Pin Friction
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Solution Overview
Problem
Existing shift lever devices for automatic transmissions require precise inspection and repair to prevent resin burrs from interfering with detent rods, which complicates the manufacturing process and affects operational feeling due to metal-on-metal contact between the shift lever main body and detent pin.
Innovation Solution
A shift lever device with a first molding resin interposed between the detent pin and long hole, and a second molding resin on the outer side to fix the main body, allowing for separate high-precision molding of the resin pieces without the need for precise inspection or repair, using softer materials for better operational feeling and harder materials for increased rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If resin is made to flow to the inner sides of the long holes during molding, then resin interposes between the detent pin and inner walls to prevent metal rubbing, but resin may project out as burrs and interfere with the detent rod
Solution Approach 1:
The resin outer tube is divided into two separate molding processes: first molding resin for the inner long hole area and second molding resin for the outer area. This segmentation allows each resin to be molded independently with optimized parameters, preventing burr formation while ensuring proper resin interposition for smooth operation.
Solution Approach 2:
The first molding resin is molded first to precisely fill the long holes and interpose between the detent pin and inner walls before the second molding resin is applied. This preliminary action ensures that the resin is properly positioned without projecting as burrs, eliminating the need for inspection and repair work.
2Strength
If metal detent pin moves within metal long holes, then structural strength is maintained, but metals rub against each other causing poor operational feeling
Solution Approach 1:
The first molding resin acts as an intermediary material between the metal detent pin and the metal long hole inner walls. This resin layer prevents direct metal-to-metal contact and rubbing, providing smooth operational feeling while maintaining the structural strength of the metal components.
Solution Approach 2:
The invention uses a composite structure combining metal (for strength) and resin (for smooth operation). The detent pin and long hole are made of metal to maintain structural strength, while resin is interposed to eliminate metal rubbing, creating a composite system that achieves both strength and ease of operation.
3Ease of manufacture
If single resin is used for both inner and outer areas, then manufacturing process is simple, but precise inspection and repair work are needed to eliminate burrs
Solution Approach 1:
The molding process is segmented into two independent steps: first molding resin for the inner area and second molding resin for the outer area. This segmentation allows each resin to be molded with optimized parameters, eliminating burr formation and eliminating the need for inspection and repair work, while the overall process remains efficient.
Solution Approach 2:
The first molding resin is preliminarily molded to precisely fill the long holes before the second molding resin is applied. This preliminary action with optimized molding parameters prevents burr formation from the outset, eliminating the need for subsequent inspection and repair work and reducing total manufacturing time.
Data Source
AI summary
A shift lever device has resin pieces, and a resin outer tube which is formed at an outer side of a shift lever main body. The resin pieces and the resin outer tube can be molded separately. Therefore, the resin pieces independently can be molded with high precision. Even in a structure in which interposed portions of the resin pieces are interposed between a detent pin and inner walls of long holes of the shift lever main body, the interposed portions do not project-out unnecessarily at an inner side of the shift lever main body. Resin can be interposed between the detent pin and the long holes of the shift lever main body, without carrying out precise inspection or repair work.