Speedometer Worm Gear Mounting Structure Reducing Axial Parts
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Solution Overview
Problem
Conventional mounting structures for speedometer drive gears require multiple parts and complex assembly processes, leading to increased costs and effort due to the need for separate stopper rings and a rotation-preventing ball, which complicates the installation and increases the number of man-hours required.
Innovation Solution
A rotary member mounting structure featuring a rotary shaft with distinct diameter portions and snap ring grooves, where first and second slide preventing members and rotation preventing structures are used to prevent axial sliding and rotation, respectively, reducing the number of parts and simplifying assembly by using snap rings and spline grooves to secure the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ball and key groove structure is used to prevent rotation of the speedometer drive gear, then the gear can be securely prevented from turning about the main shaft, but the number of parts increases and the assembly process becomes more complex
Solution Approach 1:
The patent combines the rotation prevention function with the existing key groove structure by installing the ball directly into the key groove of the speedometer drive gear, eliminating the need for separate groove portions in the main shaft. This merging of functions reduces the number of parts while maintaining reliable rotation prevention.
Solution Approach 2:
The key groove structure is given multiple functions: it serves both as the original keyway for torque transmission and as the housing for the ball that prevents rotation. This multi-functionality eliminates the need for additional dedicated rotation prevention structures.
2Reliability
If two stopper rings are installed to prevent axial sliding of the speedometer drive gear, then the gear is securely constrained in the axial direction, but the number of parts and assembly work increase
Solution Approach 1:
The patent merges the function of two separate stopper rings into a single stopper ring that works in conjunction with the rotation-preventing ball. The ball prevents sliding in one axial direction while the stopper ring prevents sliding in the opposite direction, combining the functions of two components into one.
Solution Approach 2:
The rotation-preventing ball serves dual functions: it prevents rotation of the gear about the main shaft and simultaneously prevents axial sliding in one direction. This multi-functionality reduces the total number of parts needed for axial constraint.
3Reliability
If the first stopper ring is installed into the farther stopper ring installation groove, then the gear is properly constrained, but the first stopper ring may be unintentionally inserted into the closer groove requiring removal
Solution Approach 1:
The patent extracts the rotation prevention function from the stopper ring system and assigns it to the ball component. This allows the stopper ring to be designed and installed solely for axial constraint without the complexity of preventing unintentional insertion into the wrong groove, as the ball handles the rotation prevention aspect.
Data Source
AI summary
A rotary member mounting structure is configured for mounting a speedometer worm gear closely adjacent to a drive gear that is supported on an output shaft. The rotary member mounting structure basically has a rotation preventing structure, a first fastening ring and a second fastening ring. The rotation preventing structure is configured to prevent the drive gear from rotating relative to the output shaft 1 and to prevent the worm gear from rotating relative to the output shaft. The first fastening ring is configured to prevent the drive gear from sliding axially toward the worm gear and to prevent the worm gear from sliding axially toward the drive gear; and a second fastening ring is configured to prevent the worm gear from sliding axially in the direction opposite (i.e., away from) the drive gear.