Vehicle Transmission Shift Fork Shaft Gap Design
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Solution Overview
Problem
In vehicle transmission structures, the movement of shift fork shafts can be disrupted by air or oil trapped between the shaft's end portion and the boss portion, leading to irregular shifting operations.
Innovation Solution
A vehicle transmission structure design featuring a shift drum, bearing member, set member, and shift fork shafts with damper members and strategically placed gaps to facilitate smooth axial movement of the shift fork shafts, reducing the risk of collision and improving shifting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the end portion of the shift fork shaft is fitted to the bottomed boss portion, then the shift fork shaft is supported and positioned, but air or oil becomes trapped between the shaft and boss portion, disturbing axial movement and affecting smooth shifting operation
Solution Approach 1:
The patent extracts the harmful air and oil trapped between the shift fork shaft and boss portion by providing gaps (first gap between end surface of insertion hole and damper member, second gap between end surface of insertion hole and set member) that allow these fluids to escape outward, eliminating the harmful trapping effect while maintaining the supportive function
Solution Approach 2:
The damper member acts as an intermediary element between the shift fork shaft and the transmission case structure. It provides cushioning and positioning functions while the gaps around it allow fluid escape, mediating between the need for stable support and the need for smooth axial movement
2Device complexity
If the set member is disposed at a position overlapping the insertion hole, then the position restriction of the shift fork shaft is improved and component number is reduced, but hitting sound may occur due to direct collision
Solution Approach 1:
The damper member is positioned beforehand between the shift fork shaft and the set member to provide cushioning. This prevents direct collision and hitting sounds when the shift fork shaft moves axially, while the set member maintains its position restriction function with reduced component complexity
3Ease of operation
If the first gap is provided between the end surface of the insertion hole and the damper member, then axial movement is promoted by allowing air or oil to flow outward, but the precision of shaft positioning may be affected
Solution Approach 1:
The patent applies local quality by providing gaps specifically at certain locations (between end surface of insertion hole and both damper member and set member) while maintaining precise positioning in other areas. The gaps are strategically placed to allow fluid escape and promote smooth axial movement only where needed, without compromising overall positioning precision
Data Source
AI summary
A vehicle transmission structure of an embodiment includes a shift drum which rotates in accordance with a shift operation; a bearing member which rotatably supports the shift drum with respect to a transmission case; a set member which positions the bearing member; a shift fork shaft supported by the transmission case; and a shift fork supported by the shift fork shaft to be movable in an axial direction. An end portion of the shift fork shaft is movably fitted to an insertion hole provided in the transmission case, a cap is provided at an end portion of the shift fork shaft, a first gap is provided between an end surface of the insertion hole and the cap, the set member is disposed at a position overlapping the insertion hole when viewed in the axial direction, and a second gap is provided between an end surface of the insertion hole and the set member.