Throttle Valve Shaft Slit Geometry for Burr and Leakage Control
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Solution Overview
Problem
Existing throttle valve devices face issues with burr formation and leakage due to the shape of the slit, which affects the assembly and functionality of the valve and shaft, particularly in electronic throttle devices where precise control of intake air is required.
Innovation Solution
The throttle valve device incorporates a cylindrical body with a shaft, bearings, and a valve, featuring a slit with a round end hole and a specific chamfer angle to reduce burr formation and leakage, where the round end hole is designed to match or exceed the width of the slit by 30% and is positioned to be covered by the body, and the slit is formed using a disk-shaped cutter with a diameter larger than the valve by 10-40%, ensuring effective rotation and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional slit is formed in the shaft, then the valve can be inserted and rotated, but burrs are formed at the slit end causing leakage and assembly issues
Solution Approach 1:
A round end hole is formed at the end of the slit in the shaft before the valve is inserted. This preliminary action removes the sharp edge that would otherwise generate burrs during valve insertion and rotation, preventing leakage and assembly problems.
Solution Approach 2:
The end of the slit is designed with a rounded shape (round end hole) instead of a sharp edge. This curvature eliminates stress concentration points and prevents burr formation when the valve is inserted and rotated, solving the leakage issue.
2Reliability
If the slit width is made equal to the valve thickness for precise control, then sealing is improved, but burr formation and leakage occur due to the sharp slit edges
Solution Approach 1:
The round end hole is formed at the slit end before assembly, preliminarily eliminating the sharp edge that causes leakage. This allows the slit width to be precisely matched to the valve thickness for good sealing while preventing burr-induced leakage.
Solution Approach 2:
The sharp edge at the slit end, which originally caused burr formation and leakage, is converted into a rounded edge. This rounded edge eliminates the harmful burr formation while maintaining the precise dimensional relationship between slit width and valve thickness for reliable sealing.
3Ease of operation
If the shaft and valve assembly is designed for easy rotation, then operational efficiency is improved, but stress concentration occurs at the slit ends
Solution Approach 1:
The round end hole at the slit end provides a curved transition instead of a sharp corner. This curvature eliminates stress concentration points that would otherwise occur at the slit ends during valve rotation, allowing smooth operation without stress-induced failures.
Solution Approach 2:
The round end hole is formed in advance to eliminate stress concentration points before the valve is assembled and rotated. This preliminary modification ensures that the shaft-valve assembly can rotate smoothly without developing stress-related defects.
Data Source
AI summary
A throttle valve device includes a shaft in a cylindrical passage, a slit passing through the shaft from one lateral side to another lateral side of the shaft, a pair of bearings on both sides of the cylindrical passage and rotatably supporting one end part and another end part of the shaft, and a circular-plate valve inserted into the slit of the shaft and rotatable to open and close the cylindrical passage. A length of the slit on the one lateral side of the shaft is, in an axial direction of the shaft, longer than a length of the slit on the other lateral side of the shaft. A round end hole is formed at an end of the slit in the one end part of the shaft on the one lateral side of the shaft.