Transmission Shaft Bore Layout to Prevent Hydraulic Short Circuits
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Solution Overview
Problem
Motor vehicle transmission shafts with axial bore holes face challenges in maintaining mechanical strength while preventing hydraulic short circuits due to high pressures and the need for small outer diameters, which can lead to breakthroughs between bore holes.
Innovation Solution
The shaft is divided into three axial sections with radial bore holes in the second section for fluid supply and discharge in the first and third sections, where axial bore holes are arranged in a congruent but non-coaxial manner to reduce the risk of hydraulic short circuits, and the number and distribution of bore holes are optimized for high mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the outer diameter of the shaft is reduced to keep bearings and sealing elements small, then the shaft size is minimized, but the wall thickness between bore holes becomes too small causing breakthroughs and hydraulic short circuits
Solution Approach 1:
The shaft is divided into three axial sections (first, second, and third sections) with bore holes strategically distributed across these sections. The second axial section contains bore holes that do not extend through the entire shaft length, creating segmented fluid paths that prevent hydraulic short circuits while maintaining a compact outer diameter.
Solution Approach 2:
Different axial sections of the shaft have different bore hole configurations. The second axial section has bore holes that are radially spaced apart and do not extend through the entire shaft, while the first and third sections have through-bore holes. This local variation in bore hole design allows for compact dimensions while preventing hydraulic breakthroughs in the critical middle section.
2Adaptability or versatility
If multiple axial bore holes are arranged in the shaft for fluid supply, then fluid distribution is achieved, but the mechanical strength of the shaft is reduced
Solution Approach 1:
The bore holes are segmented into different axial sections with different functions. The second axial section contains non-through bore holes that provide fluid supply without completely penetrating the shaft, thereby maintaining structural integrity while enabling fluid distribution to multiple elements.
Solution Approach 2:
The bore holes are arranged in different axial positions (first, second, and third sections) rather than being concentrated in a single location. This axial distribution allows fluid supply to multiple transmission elements while spreading the structural weakness across different sections, maintaining overall shaft strength.
3Adaptability or versatility
If deep bore holes are drilled in the shaft, then fluid supply to internal elements is achieved, but oblique drilling causes reduced wall thickness and potential breakthroughs between bore holes
Solution Approach 1:
The bore holes in the second axial section are designed as non-through holes that stop before penetrating the entire shaft length. This segmentation allows for precise control of hole depth and positioning, eliminating the risk of breakthroughs caused by oblique drilling while still providing adequate fluid supply to internal transmission elements.
Data Source
AI summary
A shaft (W) for a motor vehicle transmission (G) may have axial bore holes positioned within the shaft and configured to guide fluid within the shaft. The shaft may have first, second, and third axial sections (W1, W2, W3), the second axial section being axially between the first and third axial sections. Fluid enters the axial bore holes in the second axial section and exits the axial bore holes in the first and third axial sections. One of the axial bore holes (B2; B1, B1a) is arranged, at least partially, in the first axial section and is radially spaced from an axis of rotation (WA) of the shaft. Another of the axial bore holes (B1RS; B_SE5, B3a) is arranged, at least partially, in the third axial section. The one of the axial bore holes (B2; B1, B1a) is coaxial with the other of the axial bore holes (B1RS; B_SE5, B3a).