Integrated Master-Slave Pistons for Engine Valve Actuation
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Solution Overview
Problem
Conventional engine braking systems require dedicated components and extra space for installation, which is inefficient and limits their integration in internal combustion engines.
Innovation Solution
An apparatus with a rocker arm incorporating a master piston, slave piston, and hydraulic circuit that receives motion from both primary and auxiliary valve actuation sources, eliminating the need for dedicated components by using hydraulic fluid to transmit auxiliary valve actuation motions to engine valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dedicated components are used for engine braking, then the engine braking function is achieved, but the device complexity and space requirements increase
Solution Approach 1:
The patent combines the engine braking function with the existing valve actuation system by integrating a braking cam into the camshaft and using the existing rocker arm and valve train components. This merging approach eliminates the need for dedicated engine braking components while maintaining reliable engine braking functionality through the same mechanical pathway used for normal valve operation
Solution Approach 2:
The valve actuation components (camshaft, rocker arm, pushrod) are designed to serve dual purposes: normal valve operation during power strokes and engine braking during compression strokes. The braking cam on the camshaft provides auxiliary motion that works with the primary valve actuation cam to control valve timing and lift for both functions, making the system multi-functional without requiring separate dedicated components
2Reliability
If conventional dedicated components are used for engine braking, then the engine braking function is achieved, but the packaging space increases
Solution Approach 1:
The engine braking mechanism is merged into the existing valve actuation space. The braking cam is integrated onto the camshaft alongside the primary valve actuation cam, and the rocker arm is designed to receive motion from both cams. This integration allows the engine braking function to be achieved within the existing packaging envelope without requiring additional space for dedicated braking components
3Force
If early valve actuation is used for bleeder braking, then lower actuation force is required, but the valve must remain open longer increasing complexity
Solution Approach 1:
The system uses dynamic valve actuation where the valve timing and duration are variable rather than fixed. The rocker arm mechanism with its ability to receive motion from both the primary cam and braking cam allows the valve to be held open for extended periods at lower lift amounts during bleeder braking operations, adapting the valve motion profile to the specific braking requirement rather than using a single fixed timing pattern
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 configuration reduces the number of components needed and allows for more compact packaging, enabling efficient engine braking without the need for additional space, thereby improving engine performance and packaging efficiency.
Implementation Method 1
A hydraulic circuit is provided in the rocker arm connecting the master piston bore and the slave piston bore
Implementation Method 2
a check valve is disposed within the rocker arm, configured to supply hydraulic fluid to the hydraulic circuit
Data Source
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AI summary
An apparatus for actuating first and second engine valves comprises a rocker arm that receives motion from primary and auxiliary valve actuation motion sources at a motion receiving end of the rocker arm. A master piston residing in a master piston bore in the rocker arm is configured to received motion from the auxiliary valve actuation motion source. A slave piston residing in a slave piston bore in the rocker arm is configured to provide auxiliary valve actuation motion to the first engine valve. A hydraulic circuit is provided in the rocker arm connecting the master piston bore and the slave piston bore, and a check valve is disposed within the rocker arm, configured to supply hydraulic fluid to the hydraulic circuit. The apparatus may be incorporated into a system comprising a rocker arm shaft and the primary and secondary valve actuation motion sources, such as an internal combustion engine.