Split Linkage Valve Mechanism Tolerance Stackup
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Solution Overview
Problem
Existing EGR valve assemblies face challenges in accommodating tolerance stackup and maintaining anti-backdrive capability under varying pressures, leading to potential valve failure or unintended opening due to inadequate linkage mechanisms.
Innovation Solution
A linkage mechanism incorporating a rotatable lever and scotch yoke design, with an eccentrically positioned engagement component, that converts rotational motion to linear motion, providing enhanced opening force and anti-backdrive capability while accommodating manufacturing tolerances and maintaining low side loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a scotch yoke linkage mechanism is used with a fixed starting angle, then good low flow resolution and high opening force are achieved, but the mechanism cannot accommodate tolerance stackup in seat position
Solution Approach 1:
The linkage mechanism employs a variable starting angle design where the initial angle of the scotch yoke is not fixed but can adjust within a range. This dynamic adjustment capability allows the mechanism to adapt to different seat positions caused by tolerance stackup while maintaining reliable valve seating and accommodating variations in assembly tolerances.
2Adaptability or versatility
If the starting angle of the scotch yoke is increased to accommodate tolerance stackup, then adaptability improves, but anti-backdrive capability is diminished
Solution Approach 1:
The mechanism uses a dynamic starting angle that can be optimized for each application. By allowing adjustment of the initial angle, the system can achieve the minimum angle needed to accommodate tolerance stackup without exceeding the threshold that would compromise anti-backdrive capability, thus balancing both requirements.
Solution Approach 2:
The invention changes the parameter of the starting angle from a fixed value to a variable parameter that can be adjusted within an optimal range. This parameter change enables the mechanism to accommodate tolerance stackup while maintaining sufficient anti-backdrive capability by selecting appropriate angle values within the adjustable range.
3Reliability
If a larger motor and return spring are used to increase performance margin, then reliability and adaptability improve, but device complexity and cost increase
Solution Approach 1:
By implementing a variable starting angle mechanism, the system achieves improved reliability and adaptability through geometric optimization rather than increasing the size of motor and spring components. This approach maintains performance margin while avoiding the increased complexity and cost associated with larger actuators.
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 proposed linkage mechanism ensures reliable valve operation across a range of lift positions, maintaining high opening force and anti-backdrive capability while minimizing side loading, thus preventing valve failure and unintended opening.
Implementation Method 1
one of a slot and an engagement component operably coupled to at least one drive component of the valve assembly and located eccentrically from a rotational axis of the at least one drive component
Data Source
AI summary
A linkage mechanism for a valve assembly includes one of a slot and an engagement component operably coupled to at least one drive component and located eccentrically from a rotational axis of the at least one drive component, a link operably coupled to one end of a valve stem of a valve member and being moveable with the valve stem, the link having another one of a slot and an engagement component, and a rotatable lever coupled to at least one housing, the lever including one of a first slot and a first engagement component operably engaged with the one of the slot and the engagement component of the at least one drive component and one of a second slot and a second engagement component operably engaged with the one of the slot and the engagement component of the link, wherein rotation of the at least one drive component causes the lever to rotate to convert a rotational movement of the at least one drive component to a linear movement of the link such that the link, the valve stem, and the valve member are moved axially in a direction along a longitudinal axis of the valve stem.