Cupped End-Cap Stabilizes Valve Lift in Hydraulic Lash Adjusters
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Solution Overview
Problem
Variations in bias spring geometry within reverse-spring hydraulic lash adjusters in internal combustion engines lead to inconsistencies in valve lift and performance, affecting engine efficiency and emissions due to varying fluid flow forces on the closing body.
Innovation Solution
The introduction of an end-cap with a cupped design that minimizes or eliminates the impact of bias spring geometry variations by providing a consistent flow path resistance and impingement surface, ensuring consistent hydraulic fluid force on the closing body, thereby stabilizing valve lift across engine populations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse-spring control valve assembly is used to prevent inadvertent valve actuation, then valve control reliability is improved, but variation in end-coil geometry of bias spring causes variation in fluid flow forces leading to inconsistent valve lift
Solution Approach 1:
The end-cap serves as an intermediary component between the bias spring and closing body. It provides a standardized interface that mediates the interaction between hydraulic fluid and the closing body, eliminating the direct influence of bias spring end-coil geometry variations on fluid flow forces. The end-cap's consistent geometry ensures uniform fluid flow paths regardless of spring variations.
Solution Approach 2:
The end-cap introduces homogeneity to the system by providing a uniform, consistent geometry that all bias springs interface with. This standardized interface ensures that all closing bodies experience identical fluid flow conditions, creating homogeneous performance across all valves in the engine population despite variations in individual spring manufacturing.
2Ease of manufacture
If bias spring geometry variations are allowed due to typical manufacturing methods, then manufacturing cost and complexity are reduced, but fluid flow induced forces on closing body vary causing inconsistent valve response
Solution Approach 1:
The end-cap acts as a mediator that decouples the closing body performance from bias spring geometry variations. By introducing this intermediate component with standardized geometry, the system can accommodate inexpensive, variably manufactured springs while maintaining consistent valve response through the end-cap's uniform flow path geometry.
Solution Approach 2:
The invention extracts the source of variation (bias spring end-coil geometry) from the critical fluid flow path. By removing the spring's direct interaction with the closing body and replacing it with a standardized end-cap interface, the harmful geometric variations are taken out of the equation, allowing inexpensive spring manufacturing without compromising valve response consistency.
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
This solution reduces or eliminates variations in engine valve lift and performance, ensuring consistent engine operation and minimizing engine-to-engine differences in valve lift, thereby enhancing engine efficiency and reducing emissions.
Implementation Method 1
A reverse-spring control valve design is shown in FIGS. 12 and 13, contained within a hydraulic pivot element 110. Reverse-spring designs typically employ a bias spring 134 that engages a top portion of a closing body 142 of a control valve assembly 130, providing for a biased-open configuration.
Implementation Method 2
engagement of the closing body 142 with a valve seat 144 formed on a bottom surface 131 of the piston 126 occurs when a resultant fluid force F2 acting on the closing body 142 overcomes a bias spring force F3
Implementation Method 3
The end-cap minimizes or eliminates the variation in fluid flow induced forces on the closing body caused by a variation in end-coil geometry of the second lower end of the bias spring
Data Source
AI summary
A lash compensator for a valve train component of an internal combustion engine is provided that includes an end-cap arranged within a reverse-spring control valve assembly of an axially moveable piston. The piston has a first reservoir and an inner radial wall configured with a through-aperture. The reverse-spring control valve assembly has a control valve housing, a bias spring, an end-cap, and a closing body. The end-cap is configured with a cupped end; an inner side of the cupped end receives a second lower end of the bias spring, and an outer side of the cupped end engages an upper portion of the closing body. The end-cap minimizes or eliminates the variation in flow resistance caused by a variation in end-coil geometry of the second lower end of the bias spring.