Shift Lever Knob Geometry for Large Rod Stroke in Tight Space
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Solution Overview
Problem
Existing shift lever devices require a large space for operation due to a high ratio of rotation stroke to rod stroke, compromising compactness and design efficiency.
Innovation Solution
A shift lever device with a hollow shaft-shaped lever main body, a hollow knob, a rotating member with a contact surface that extends away from the rotating shaft, and an urging member that lowers a rod, optimizing the rotation range to achieve a larger rod stroke with a smaller rotation stroke, and incorporating a guide hole with an inclined contact surface to prevent abnormal noise and ensure durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the rotation stroke amount of the shift button is increased to achieve a given rod stroke amount, then the rod stroke amount is sufficient, but a large space is needed for operation of the shift button, leading to the shift lever becoming large
Solution Approach 1:
The patent changes the geometric parameters of the contact surface, specifically setting it at a 45-degree angle and positioning it at the distal end of the rotating member. This parameter optimization allows the rod stroke amount to be maximized while minimizing the rotation stroke amount of the shift button, achieving a compact design with sufficient rod displacement.
Solution Approach 2:
The contact surface is positioned at the distal end of the rotating member rather than at the center, utilizing the radial dimension of the rotating member. This dimensional arrangement creates a lever arm effect where a small rotation angle of the shift button produces a large linear displacement of the rod, effectively converting rotational motion into linear motion with high efficiency.
2Volume of moving object
If the rotation stroke amount of the shift button is reduced to achieve compactness, then the design compactness is improved, but the rod stroke amount becomes insufficient
Solution Approach 1:
By optimizing the contact surface angle to 45 degrees and positioning it at the distal end of the rotating member, the patent achieves maximum mechanical advantage. This allows a small rotation stroke of the shift button to generate sufficient rod stroke amount, resolving the contradiction between compactness and operational effectiveness.
3Length of moving object
If the contact surface is positioned to maximize rod stroke, then the rod stroke amount is sufficient, but abnormal noise and durability issues occur
Solution Approach 1:
The contact surface is set at a 45-degree angle, which optimizes the force transmission direction. This angle ensures that the rod is pushed downward effectively while maintaining proper alignment with the guide hole, preventing lateral forces that would cause noise and wear. The distal end positioning further ensures that the force is applied at the optimal point for both stroke generation and smooth operation.
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 device effectively reduces the rotation stroke requirement while increasing the rod stroke, enhancing compactness and preventing noise and durability issues, thus improving design efficiency and user experience.
Implementation Method 1
an urging member that is disposed at the interior of the lever main body, and that is configured to urge the rod toward an upper side
Data Source
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AI summary
A shift lever device includes: a lever main body; a knob 28 that is hollow and is provided at a distal end portion of the lever main body; a shift button 30 that is rotatably mounted to the knob 28; and a rod 32 that is inserted-through an interior of the lever main body. The shift button 30 has a contact surface 30c that extends in a direction of being away from a rotating shaft 30a of the shift button 30, and that, when the shift button 30 rotates with respect to the knob 28, contacts an upper end portion of the rod 32 and lowers the rod 32. Given that a direction orthogonal to an axial direction Z of the rotating shaft 30a on a plane orthogonal to an axis CL1 of the rod 32 is reference direction X, and that, among tangent lines at contact points of the contact surface 30c and the rod 32, a tangent line that is on a plane orthogonal to the rotating shaft 30a is a reference tangent line Lct, a rotation range of the shift button 30 is set such that, partway through rotation, the reference tangent line Lct passes a position at which the reference tangent line Lct becomes parallel to the reference direction X.