Valve Actuation Mechanism With Elastic Stopper For Engine Brake Control
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Solution Overview
Problem
Existing valve actuation mechanisms for internal combustion engines in automotive vehicles face challenges in accurately reducing fluid pressure with low forces and ensuring timely valve closure to prevent extended valve overlap during engine brake functions, particularly in single valve engine braking systems.
Innovation Solution
A valve actuation mechanism that incorporates an elastic stopper with variable force, which increases as the rocker rotates from the valve closing to opening position, allowing precise control of fluid release and valve closure, utilizing a combination of main and auxiliary springs to manage the force exerted on the rocker and check valve, ensuring synchronized valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stopper is used to open the check valve and release fluid pressure, then the piston can be reset to its initial position, but the valve closure timing cannot be precisely controlled
Solution Approach 1:
The invention changes the parameter of force application by using an elastic stopper that exerts a progressive force on the check valve. The elastic stopper's force increases as it is compressed during rocker rotation, providing precise control over when the check valve opens and fluid pressure is released, thereby precisely controlling valve closure timing.
2Duration of action of moving object
If control pressure is continuously sent to the control valve during engine brake function, then the activation piston remains in the engine brake actuation position, but the piston cannot be reset when retraction is needed for a period inferior to one revolution of the camshaft
Solution Approach 1:
The elastic stopper provides a self-service mechanism for resetting the piston. As the rocker rotates during normal valve operation, the elastic stopper is compressed and automatically opens the check valve to release fluid pressure, resetting the piston without requiring external control pressure management or additional control valve operations.
3Reliability
If the check valve is forced open to allow control fluid to escape, then the piston can be reset, but the valve closure timing becomes delayed and extended valve lift overlap occurs
Solution Approach 1:
The invention applies a dynamic force mechanism through the elastic stopper that progressively compresses during rocker rotation. The force exerted by the elastic stopper on the check valve increases dynamically, ensuring the check valve opens at the precise moment when the rocker reaches the appropriate position, thereby preventing delayed valve closure and extended valve lift overlap.
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 mechanism effectively reduces fluid pressure with high accuracy and low forces, preventing extended valve overlap and enhancing the efficiency of engine brake functions by ensuring synchronized closure of valves.
Implementation Method 1
the stopper comprises elastic means which are stressed when the rocker travels from its valve closing position to its valve opening position
Implementation Method 2
the stopper comprises a spring adapted, when deformed, to exert a compression force on said member
Data Source
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AI summary
The invention proposes a valve actuation mechanism (S) for an internal combustion engine (E) on an automotive vehicle, comprising rockers (9) moved by a camshaft (2), each rocker (9) being adapted to exert a valve opening force (F9) on at least a portion of a opening actuator (7) of each cylinder, via an activation piston (95) of the rocker (9) movable with respect to the rocker (9) under action of a fluid pressure raise in a chamber (101), from a first position to a second position, in which a cam follower (93) of the rocker (9) is adapted to read at least one auxiliary valve lift sector of a cam (22) of the camshaft (2) so as to perform an engine operating function, each rocker (9) comprising a valve (97; 99; 103; 106) for releasing fluid from the chamber (101), wherein the valve actuation mechanism (S) comprises, for each rocker (9), a stopper (13) fast with a housing (E1) of the engine (E) and adapted to exert, on a member (978; 991; 95) of the rocker (9), a variable force (F136) for opening the fluid releasing valve (97; 99; 103; 105).