Shift Fork Shaft Oil Groove for Reliable Transmission Lubrication
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Solution Overview
Problem
Existing dog-clutch type stepped transmissions face challenges in efficiently supplying oil to the slidable portions of shift forks, leading to insufficient oil supply and increased machining complexity and cost due to the need for complex oil supply paths and precise alignment.
Innovation Solution
A transmission design featuring a shift fork shaft with an axial oil supply path and a circumferential groove on the outside, allowing oil to be supplied directly to the slidable portion of the shift fork, with a depressed portion on the boss portion extending only 180° or less, facilitating easier machining and ensuring consistent oil delivery even with misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil supply pipe is provided separately from the shift fork shaft to spray oil to the slidable portion, then oil supply is achieved, but the amount of oil supply is insufficient and the number of parts and size of the transmission increase
Solution Approach 1:
The oil supply path is integrated into the shift fork shaft itself, merging the oil supply function with the shift fork shaft structure. This eliminates the need for a separate oil supply pipe, reducing the number of parts while ensuring sufficient oil supply to the slidable portion of the shift fork through the circumferential groove and oil supply hole.
2Reliability
If a depressed portion is formed on the inner circumferential surface of the boss portion to guide oil, then oil supply to the slidable portion is achieved, but machining becomes difficult and time-consuming
Solution Approach 1:
The depressed portion is designed to extend only over a specific angular extent (180° or less) of the inner circumferential surface, rather than the entire circumference. This localized approach provides sufficient oil guidance to the slidable portion while significantly reducing machining time and complexity compared to forming a complete circumferential depressed portion.
3Reliability
If the depressed portion extends over the entire inner circumferential surface, then oil supply reliability is improved, but machining time and cost increase
Solution Approach 1:
The depressed portion extends over a partial extent (180° or less) of the inner circumferential surface, which is sufficient to guide oil effectively to the slidable portion of the shift fork. This partial action achieves the necessary oil supply reliability without the excessive machining time and cost that would result from forming a complete 360° circumferential depressed portion.
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 design enables efficient direct oil supply to the shift fork, reducing machining time and cost while maintaining effective lubrication, and allows for smoother gear-shifting operations with improved precision and reduced assembly complexity.
Implementation Method 1
a circumferential groove 104 that is formed on the outside of the shift fork shaft 100 so as to make a complete round around the shift fork shaft 100
Implementation Method 2
an oil supply hole 103a that extends in a radial direction so as to connect between the oil supply path 103 and the circumferential groove 104
Implementation Method 3
a depressed portion 91d that is formed on the inner circumferential surface 91a and is connected to the oil hole 97. The depressed portion 91d overlaps with the circumferential groove 104 of the shift fork shaft 100
Data Source
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AI summary
A shift fork shaft 100 includes an oil supply path 103 that extends in an axial direction, a circumferential groove 104 that is formed on an outside of the shift fork shaft 100, and an oil supply hole 103a that extends in a radial direction so as to connect between the oil supply path 103 and the circumferential groove 104. An oil hole 97 extending in the radial direction is formed in a boss portion 91 of a shift fork 90. The boss portion 91 includes an inner circumferential surface 91a, wherein a depressed portion 91d that is connected to the oil hole 97 is formed on the inner circumferential surface 91a. The depressed portion 91d is formed to extend in a circumferential direction over an extent of 180° or less of the inner circumferential surface 91a and overlaps with the circumferential groove 104 of the shift fork shaft 100.