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, a screw hole, and a circular plate-shaped valve, featuring a round end hole at one end of the slit with a predetermined angle and depth, and a slit formed by a disk-shaped cutter, reducing burr formation and leakage by ensuring the slit's dimensions and angle are optimized for smooth operation.
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 screwed, but burr formation occurs at the slit end causing leakage and assembly issues
Solution Approach 1:
A round end hole is formed at the end of the slit before the slit is completely formed. This preliminary action prevents burr formation by providing a rounded transition zone at the slit end, eliminating sharp edges where burrs would otherwise form during the cutting process.
Solution Approach 2:
The end of the slit is formed with a round end hole instead of a sharp angular end. This curvature eliminates the sharp edges that cause burr formation during cutting, creating a smooth rounded transition that prevents material accumulation and improves assembly quality.
2Reliability
If the slit width is made equal to the valve thickness for precise fit, then leakage is reduced, but assembly becomes difficult due to burr formation
Solution Approach 1:
The round end hole is formed as a preliminary feature before final slit completion. This pre-formed rounded end provides a smooth transition zone that prevents burr formation, allowing the slit width to be precisely matched to the valve thickness for leakage prevention while maintaining ease of assembly.
Solution Approach 2:
By rounding the slit end with a round end hole, the sharp edges that cause burrs are eliminated. This allows the slit width to be precisely controlled to match the valve thickness for reliable sealing, while the rounded end ensures smooth assembly without burr-related difficulties.
3Manufacturing precision
If the slit is formed by a small cutter for precision, then the slit width matches the valve, but burr formation increases at the slit end
Solution Approach 1:
The round end hole is formed as a preliminary feature at the slit end before the cutting process completes. This preliminary rounding action ensures that even when a small precision cutter is used to achieve accurate slit width matching, burr formation is prevented by the pre-formed rounded transition zone.
Solution Approach 2:
The round end hole provides a curved transition zone at the slit end that eliminates sharp edges. This allows the use of small precision cutters to achieve accurate slit width control while the rounded end prevents burr formation that would otherwise occur with sharp cutting edges.
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.