Exhaust Valve Secondary Rocker Arm Spring Stabilization
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Solution Overview
Problem
The existing exhaust valve mechanism for internal combustion engines experiences undesired wear and damage due to the secondary rocker arm's angular movement and unilateral loading during engine braking, which reduces the oil film thickness at its bearing point, leading to increased wear.
Innovation Solution
A spring device is arranged between a fixed point on the engine and the secondary rocker arm to engage with the cam element, preventing unwanted movement and increasing the oil film thickness at the bearing point by applying a spring force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the secondary rocker arm is allowed to move angularly during engine braking, then the valve mechanism can accommodate the braking function, but undesired wear and damage occur due to reduced oil film thickness
Solution Approach 1:
The spring device applies a preliminary counteracting force to the secondary rocker arm to prevent unwanted angular movement during engine braking. This preliminary action maintains the rocker arm in a stable position, ensuring continuous oil film formation at the bearing point while still allowing the mechanism to accommodate the braking function through controlled engagement with the cam element.
Solution Approach 2:
The spring device changes the positional parameter of the secondary rocker arm by applying a restoring force that maintains optimal angular position. This parameter control ensures the bearing point remains in the correct position for adequate oil film thickness, thereby improving wear resistance while preserving the braking capability.
2Ease of operation
If the secondary rocker arm engages with the cam element during normal operation, then the valve mechanism functions correctly, but unilateral loading reduces oil film thickness and increases wear
Solution Approach 1:
The spring device acts as a counterbalancing element that applies a force opposite to the unilateral loading during engine braking. This counterforce reduces the net load on the bearing point, maintaining adequate oil film thickness and preventing the reduction in bearing durability that would otherwise occur during high-load braking operation.
Solution Approach 2:
The spring device provides beforehand cushioning by maintaining a pre-loaded position of the secondary rocker arm that prevents excessive engagement forces. This preliminary cushioning effect protects the bearing point from high unilateral loads during engine braking, ensuring continuous lubrication and reduced wear.
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 wear in the valve mechanism by stabilizing the secondary rocker arm's position and maintaining a thicker oil film, thereby minimizing damage and enhancing the mechanism's durability.
Implementation Method 1
a spring device is so arranged as to act between a fixed point on the engine and the secondary rocker arm, in such a way that the latter rocker arm is caused by the spring force to engage with the cam element of the camshaft
Implementation Method 2
which activation is achieved through the supply of hydraulic pressure to a piston cylinder which acts between both the rocker arms
Data Source
AI summary
An exhaust valve mechanism for an internal combustion engine with at least one exhaust valve in every engine cylinder includes a main rocker arm mounted on a rocker arm shaft and a secondary rocker arm arranged on the main rocker arm and mounted on the rocker arm shaft for the activation of an exhaust brake function. A spring device is so arranged as to act between a fixed point on the engine and the secondary rocker arm, in such a way that the latter rocker arm is caused by the spring force to engage with the cam element of the camshaft.