Reset Valve Actuation via Segmented Cam Follower
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Solution Overview
Problem
Existing gas exchange valve mechanisms for internal combustion engines require increased structural rigidity and wear due to the necessity of opening the reset valve under pressure, which limits design slimness and independence from rocker arm position.
Innovation Solution
Incorporating a second cam follower for independent actuation of the reset valve, allowing it to open when the gas exchange valve is closed, reducing pressure on the actuator piston and minimizing component wear, with a reset member and arced cam follower for prolonged contact and smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reset valve is opened under pressure using the existing cam follower mechanism, then the gas exchange valve can be reset, but increased structural rigidity and component wear are required
Solution Approach 1:
The reset function is segmented from the main valve actuation function. A separate reset cam follower (5) and reset cam element (7) are introduced to independently control the reset valve (22), allowing it to open when the gas exchange valve is closed and pressure is low, thereby reducing structural rigidity requirements.
Solution Approach 2:
The reset cam element (7) acts as an intermediary mechanism that enables the reset valve to open at the appropriate moment in the cycle. By using this intermediate cam-based actuation system, the reset valve can be opened without requiring high structural rigidity during high-pressure operation.
2Ease of operation
If the reset valve is actuated by the existing cam follower mechanism, then the valve can be controlled, but increased wear occurs due to operation under pressure
Solution Approach 1:
The reset cam element (7) is designed to open the reset valve (22) in advance, when the gas exchange valve is still closed and pressure in the actuator cylinder is low. This preliminary action allows the reset valve to be actuated under favorable low-pressure conditions, minimizing wear on the valve components.
3Device complexity
If the reset valve control is dependent on rocker arm position, then the mechanism is simpler, but design slimness is limited
Solution Approach 1:
The control mechanism is segmented into two independent cam follower systems: one for main valve actuation and one for reset valve control. This segmentation allows the reset valve to be controlled independently of rocker arm position, enabling a slimmer overall design while maintaining functional independence.
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
Enables a slimmer design with reduced wear and structural rigidity requirements, allowing independent control of the reset valve and extended opening time, facilitating efficient engine brake operation.
Implementation Method 1
a reset valve actuator (23) arranged to open and close the reset valve (22). The reset valve actuator (23) includes a cam element (29), a second cam follower (27) and a reset member (25)
Implementation Method 2
The second cam follower (27) includes an arced concave portion (27a) faced toward said cam element
Data Source
AI summary
A valve mechanism for an internal combustion engine is operable to selectively open and close a gas exchange valve to accomplish an engine brake during an engine brake mode of an engine. The valve mechanism includes a cam follower in biased abutment against a gas exchange cam element for actuation of a rocker arm connected to the gas exchange valve.