Variable Speed Drive Shift Fork Spring Bearing
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Solution Overview
Problem
The drum type-variable speed drive experiences increased operational load and friction due to the constant biasing force of the lost motion spring, which hinders smooth gear shifting operations.
Innovation Solution
The implementation of a spring bearing member and locking mechanism on the shift fork shaft allows the lost motion spring to act only when the shift fork moves, reducing friction and load by preventing constant pressure on the guide groove, and enabling a compact, easily assembled mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lost motion spring constantly biases the shift fork toward the transmission gear, then the dog clutch can mesh reliably, but rotational friction on the shift drum increases and operation load increases
Solution Approach 1:
The patent makes the spring bearing member movable along the shift fork shaft axis rather than fixed. This allows the spring load to be dynamically applied only when needed for clutch meshing, rather than constantly pressing the shift fork against the guide groove wall, thereby reducing rotational friction while maintaining meshing reliability
Solution Approach 2:
The spring bearing member acts as an intermediary between the lost motion spring and the shift fork. It transmits the spring load only when the shift fork shaft moves axially, preventing constant pressure on the guide groove and reducing friction during normal operation while still enabling reliable clutch engagement when needed
2Stability of the object's composition
If the lost motion spring constantly acts on the shift fork, then the shifter member is maintained in position, but the engaging pin portion is constantly pressed against the guide groove wall causing friction
Solution Approach 1:
The spring bearing member is designed to move axially along the shift fork shaft, changing its position from fixed to movable. This dynamic configuration allows the spring load to be applied intermittently only when the shift fork shaft moves, rather than constantly, thereby reducing energy loss through friction while maintaining position stability when needed
Solution Approach 2:
The spring load application becomes periodic rather than continuous. The spring bearing member moves axially with the shift fork shaft during gear shifting operations, causing the spring load to be applied periodically only when needed for maintaining position or assisting meshing, rather than constantly, thus reducing continuous frictional 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 minimizes rotational friction on the shift drum, reduces operational load, and facilitates smoother and more accurate gear shifting, while allowing for easier assembly and a more compact design.
Implementation Method 1
A lost motion spring is interposed between the spring bearing member and the shift fork
Implementation Method 2
rotational friction on the shift drum, which increases the operation load at the time of shifting
Data Source
AI summary
A drum type-variable speed drive wherein a spring bearing member, which is restricted from moving in the axial direction of departing from a shift fork by a locking member fixed to a shift fork shaft, is pivotally supported by the shift fork shaft. A lost motion spring is interposed between the spring bearing member and the shift fork. Movement of the shift fork shaft in the axial direction caused by rotation of a shift drum presses the spring bearing member through the locking member, whereby the spring load of the lost motion spring acts on the shift fork.