Exhaust Valve Flap Stabilizer for Ceramic Pin Chatter Control
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Solution Overview
Problem
The use of ceramic pins in motor vehicle exhaust valves, which are brittle and prone to breaking under excessive stress, results in a play between the flap and the slot, causing chattering noise due to variable exhaust gas forces, leading to a poor user experience.
Innovation Solution
A stabilizing member with protruding portions is secured to the flap, contacting the pin's bearing face to prevent pivoting and reduce noise, utilizing a metal plate attached by welding and engaging in a notch to maintain contact with the pin, ensuring stability and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic pin is used in the valve, then tribological characteristics are improved, but the pin becomes brittle and prone to breaking under excessive stress
Solution Approach 1:
The slot width is locally increased at specific positions to create clearance zones that prevent excessive stress concentration on the ceramic pin, allowing the pin to maintain its tribological advantages while reducing breakage risk
2Temperature
If the slot width is increased to accommodate thermal expansion of the flap, then thermal expansion is accommodated, but play is created between the flap and slot walls
Solution Approach 1:
The slot width is made variable along its length, being narrower at some positions and wider at others, allowing the system to dynamically adapt to thermal expansion while maintaining stability through strategic clearance zones
3Temperature
If play is left between the flap and slot walls, then thermal expansion is accommodated, but chattering noise occurs due to to-and-fro movements of the flap
Solution Approach 1:
The slot width is locally varied to create specific clearance zones that prevent the flap from making repetitive contact with the slot walls, thereby eliminating chattering noise while still accommodating thermal expansion
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 solution effectively eliminates chattering noise by stabilizing the pin relative to the flap, enhancing the operational reliability and quality of motor vehicle exhaust systems in a simple and cost-effective manner.
Implementation Method 1
each protruding portion being in contact with the bearing face of the pin
Implementation Method 2
The stabilizing member is attached, in particular welded, on the flap
Data Source
AI summary
A valve comprises a flap, a tubular valve body defining an exhaust gas flow passage, and a device to guide the flap relative to the valve body to allow the flap to pivot relative to the valve body around a pivot axis between a closing position and a freed position of the exhaust gas flow passage. The flap has two large faces substantially parallel to one another and connected to one another by an edge of the flap. The guide device comprises a pin, a distal, end and a base. The valve also comprises a stabilizing member secured to the flap.