Three-Way Valve Return Drive Mechanism for Spring Failure
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Solution Overview
Problem
Existing three-way EGR valves in motor vehicles can malfunction due to failure of the return spring or hard points in their kinematics, leading to engine performance deterioration and potential engine shutdown, especially when the air damper remains closed.
Innovation Solution
The implementation of a three-way valve with a toothed crown sector and pilot wheel mechanism that allows the valve to maintain operation even in the event of return spring failure, using a toothed crown sector with return and drive stops to cooperate with control means and overcome potential interference, ensuring continued engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a return spring is used to return the air damper to its rest position, then the valve can automatically reset after actuation, but the system becomes vulnerable to spring failure which causes engine shutdown
Solution Approach 1:
The patent applies beforehand cushioning by providing a return drive mechanism that activates automatically when the return spring fails. The return drive includes a ratchet wheel and pawl mechanism that engages to rotate the control ring and reopen the air damper when the spring can no longer exert sufficient force, preventing engine shutdown before it occurs.
Solution Approach 2:
The patent uses an intermediary mechanism (the return drive with ratchet and pawl) that mediates between the failed return spring and the air damper. When the spring fails, the return drive acts as an intermediary to provide the necessary force to reopen the damper, bridging the gap between the failed component and the required function.
2Object-generated harmful factors
If the air damper remains closed due to return spring failure, then emission control is maintained, but engine performance deteriorates and shutdown may occur
Solution Approach 1:
The patent implements feedback through the return drive mechanism that monitors the state of the return spring. When the spring fails to return the air damper properly, the feedback mechanism (ratchet engagement) automatically activates to reopen the damper, creating a closed-loop system that maintains engine performance by detecting and responding to spring failure conditions.
3Device complexity
If a simple return spring mechanism is used, then the device complexity is low, but the system lacks fault tolerance and requires engine shutdown on failure
Solution Approach 1:
The return drive mechanism serves as beforehand cushioning against spring failure. It remains dormant during normal operation, maintaining simple device complexity, but activates automatically when the spring fails, providing fault tolerance without requiring permanent complexity or engine shutdown procedures.
Data Source
Figure 1
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AI summary
A three-way, two-leaf valve comprising common control means (9) for both leaves and actuating means (12, 13, 50) arranged to pivot each of the two leaves from its open to its closed position on one of the ports, with a time lag such that, initially, the common control means pivot the second leaf, the first leaf remaining in a standby position under the action of return means, and subsequently, said control means, while continuing to pivot the second leaf, begin to pivot the first leaf, characterized in that said second actuating means (12, 50) includes a return drive means (71) enabling the second leaf (5) to pivot back to its first position under the action of the common control means (9) in the event of a failure of said return means.