Rotating Disc Anti-Sticking Engine Shutoff Valve
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Solution Overview
Problem
Conventional engine shutoff valves are prone to sticking closed after shutting down a diesel engine due to overspeed conditions, which can lead to engine destruction and personal injury, and lack resistance to high temperatures and manufacturing tolerances.
Innovation Solution
A shutoff valve with a disc assembly and anti-friction ring made of low-friction material like PTFE, allowing the disc member to rotate freely and prevent sticking, and a spring mechanism to bias the disc towards the open position, ensuring easy re-opening after an overspeed condition is resolved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional spring-loaded poppet valve is used to shut off air supply during overspeed conditions, then the valve can effectively stop the engine runaway, but the valve disc tends to stick closed and fail to reset to the open condition
Solution Approach 1:
The valve disc is designed to rotate about a pivot point during operation. When the valve closes, the disc rotates to engage with the valve seat. When the valve needs to reopen, the disc automatically rotates back to its original position, preventing sticking and ensuring reliable reset capability without additional mechanisms.
Solution Approach 2:
The invention changes the operational parameters of the valve disc by introducing rotational movement instead of simple linear motion. This rotational parameter change allows the disc to clear the valve seat during opening and prevents adhesion, fundamentally altering how the valve transitions between open and closed states.
2Reliability
If the valve disc intimately engages the valve seat to cut off air supply, then the engine shutdown is effective, but the valve becomes prone to sticking closed due to friction and thermal conditions
Solution Approach 1:
The rotating disc design introduces dynamic movement that prevents static friction from taking hold. The continuous rotational capability ensures the disc surface does not remain stationary against the valve seat, thereby preventing thermal sticking and friction-induced adhesion even during prolonged closed operation.
Solution Approach 2:
The rotational mechanism introduces micro-vibrations and movement during the closing and opening processes. This mechanical motion prevents the disc from settling into a stuck position by constantly disrupting the contact interface between the disc and valve seat, reducing the effects of thermal expansion and friction.
3Ease of manufacture
If the valve is designed with simple construction for ease of manufacture, then production complexity is reduced, but resistance to high temperatures and manufacturing tolerances is compromised
Solution Approach 1:
The rotational disc mechanism is designed with simple geometry that is easy to manufacture while inherently compensating for thermal expansion and manufacturing tolerances. The pivot-point rotation allows for natural adjustment and clearance maintenance across temperature ranges without requiring complex adjustment mechanisms.
Solution Approach 2:
The invention uses parameter changes in the form of rotational clearance and angular positioning to accommodate manufacturing tolerances. The rotational design allows for built-in clearance that compensates for dimensional variations, maintaining reliable operation across different manufacturing batches and temperature conditions without increasing complexity.
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 valve effectively prevents engine destruction by ensuring reliable shutdown and re-start capabilities, maintaining operational integrity even under high temperatures and varying pressures, and is simple in construction to reduce manufacturing complexities.
Implementation Method 1
The anti-friction ring is formed of material having a very low coefficient of friction, e.g., PTFE
Implementation Method 2
The closing force on the valve is provided by the intake air flow passing through the valve which operates to overcome a bias provided by a spring in the valve
Data Source
AI summary
An engine shutoff valve is provided which includes a valve body having an air passageway in which a disc assembly and a valve seat assembly are located. The disc assembly includes a disc member which is arranged to be rotated and moved toward the valve seat assembly upon the occurrence of an engine runaway condition to close the valve. The valve seat assembly includes an anti-friction ring which is arranged to be engaged by the disc member when the valve is closed. The anti-friction ring is rotatable with respect to the valve body and the disc member to prevent the disc member from sticking thereto after closure of the valve, whereupon the valve can be readily reopened.