Rocker Arm Assembly Engine Braking Valve Control
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Solution Overview
Problem
Current compression engine braking systems in valve train assemblies lack efficient control over exhaust valve opening and closing, leading to suboptimal braking performance due to the lack of precise control over oil pressure and valve actuation.
Innovation Solution
The exhaust valve rocker arm assembly incorporates a rocker shaft with a pressurized oil supply conduit, a rocker arm with an oil supply passage, a hydraulic lash adjuster assembly, and an accumulator assembly that stores oil and releases it through a spigot mechanism, allowing for controlled actuation of the valve bridge to open and close exhaust valves with precise oil pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a typical valve train assembly with rocker arm and hydraulic lash adjuster is used for compression engine braking, then the basic valve actuation function is provided, but precise control over exhaust valve opening distance and timing is insufficient
Solution Approach 1:
The valve train assembly is segmented into functionally distinct components: a rocker arm for actuation, a valve bridge for force transmission, and a hydraulic lash adjuster assembly with accumulator for precise control. This segmentation allows each component to be optimized for its specific function, enabling precise valve opening distance control while maintaining manageable overall complexity.
Solution Approach 2:
The hydraulic lash adjuster assembly incorporates a movable plunger body that can transition between extended and retracted positions, and an accumulator piston that moves between closed and open positions. This dynamic capability allows the system to precisely control valve opening distance by adjusting hydraulic pressure and plunger position, transforming a static valve train into a dynamically controllable system.
2Reliability
If pressurized oil is used to actuate the exhaust valve for engine braking, then braking performance is improved, but control over oil pressure and valve actuation timing becomes more difficult
Solution Approach 1:
The hydraulic lash adjuster assembly acts as an intermediary between the pressurized oil supply and the valve actuation mechanism. It includes a plunger body that responds to oil pressure changes and an accumulator that stores and releases oil in a controlled manner. This intermediary system translates pressurized oil flow into precise valve actuation timing and duration, making oil pressure control more manageable and reliable for engine braking.
Solution Approach 2:
The system utilizes hydraulic principles through the lash adjuster assembly that uses pressurized oil to control plunger position and valve actuation. The accumulator stores a predetermined amount of oil under pressure and releases it through controlled passages, enabling reliable and repeatable valve opening for engine braking without requiring complex external pressure control systems.
3Reliability
If the rocker arm is designed to open both exhaust valves simultaneously, then the valve train structure is simplified, but braking performance is reduced due to inability to control individual valve opening
Solution Approach 1:
The valve control mechanism is segmented into independent control paths for each exhaust valve. The rocker arm can selectively actuate the first or second exhaust valve through the valve bridge, and the hydraulic lash adjuster assembly can independently control the opening distance of each valve. This segmentation enables differentiated valve opening patterns required for optimal engine braking performance while maintaining a relatively simple overall structure.
Solution Approach 2:
The system enables parameter changes in valve actuation by allowing different opening distances and timing for each exhaust valve. The hydraulic lash adjuster assembly can adjust the plunger body position to control valve opening distance, and the rocker arm rotation angle can be varied to control timing. These parameter adjustments provide multiple braking modes and optimize braking performance without requiring a completely complex valve train design.
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 enables precise control over exhaust valve opening and closing, enhancing braking performance by ensuring the first valve opens a predetermined distance while the second valve remains closed, and subsequently opening both valves with further rotation, thereby improving the engine braking functionality.
Implementation Method 1
pressurized oil is communicated through the pressurized oil supply conduit, through the rocker arm oil supply passage and against the actuator
Implementation Method 2
An accumulator assembly can be disposed in the rocker arm and include an accumulator piston that translates within the accumulator piston housing between closed and open positions. The accumulator assembly is configured to store a predetermined amount of oil
Data Source
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AI summary
An exhaust valve rocker arm assembly operable in a combustion engine mode and an engine braking mode can include a rocker shaft and a rocker arm. The rocker shaft can define a pressurized oil supply conduit. The rocker arm can receive the rocker shaft and is configured to rotate around the rocker shaft. The rocker arm can have an oil supply passage defined therein. A valve bridge can engage a first exhaust valve and a second exhaust valve. A hydraulic lash adjuster assembly can include first and second plunger bodies, the first plunger body can engage the valve bridge.