Engine Brake Valve Sequencing for Intake Counterflow Control
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Solution Overview
Problem
Existing engine braking systems experience excessive loading on the intake valve train and counter flow in the intake manifold due to incomplete deactivation of main event exhaust motion, leading to high-pressure pulses and potential surge in the upstream turbocharger.
Innovation Solution
Implementing a system with precise control of valve motion using solenoid valves and lost motion devices to deactivate main event motions and activate auxiliary braking motions, combined with strategies to manage intake counter flow through airflow management devices and staged cylinder braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If enhanced engine braking systems are implemented with hydraulic piston actuation, then engine braking effectiveness is improved, but excessive loading occurs on the intake valve train due to incomplete deactivation of main event exhaust motion
Solution Approach 1:
The system performs preliminary deactivation of the main event exhaust motion through hydraulic piston actuation before the intake valve opens. This preliminary action ensures that the exhaust valve is already in the closed position when the intake valve begins its opening stroke, preventing the intake valve from opening against high cylinder pressure and thus eliminating excessive loading on the intake valve train.
Solution Approach 2:
The system uses sensor feedback to monitor valve positions and timing, and the controller adjusts the hydraulic piston actuation timing and duration based on this feedback. This closed-loop control ensures precise coordination between exhaust valve closure and intake valve opening, optimizing the deactivation sequence to prevent excessive loading while maintaining effective engine braking.
2Device complexity
If main event exhaust motion is not fully deactivated before intake valve opening, then valve timing control is simplified, but high-pressure pulses occur in the intake manifold causing counter flow and turbocharger surge
Solution Approach 1:
The system replaces traditional mechanical valve timing control with hydraulic piston actuation controlled by a solenoid valve and controller. This substitution enables precise and independent control of exhaust valve closure timing, allowing the system to fully deactivate main event exhaust motion before intake valve opening, thereby preventing high-pressure pulses, counter flow, and turbocharger surge while maintaining manageable control complexity through electronic control.
3Manufacturing precision
If hydraulic piston actuation is used for valve deactivation, then precise valve motion control is achieved, but system complexity increases with additional hydraulic components
Solution Approach 1:
The hydraulic piston serves multiple functions: it acts as both the actuator for exhaust valve closure and the mechanism for maintaining valve position during the transition period. The same hydraulic system that provides precise valve motion control also functions as the deactivation mechanism, eliminating the need for separate mechanical deactivation components and thereby reducing overall system complexity despite the precision control capabilities.
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
Reduces excessive loading on the intake valve train, minimizes counter flow, and prevents high-pressure pulses, ensuring efficient and controlled engine braking without compromising turbocharger performance.
Implementation Method 1
A solenoid valve may be controlled to provide hydraulic fluid under pressure to the braking circuit
Implementation Method 2
provide hydraulic fluid under pressure to the braking circuit
Data Source
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AI summary
Systems and methods for managing excessive intake flow path pressure and counter flow are implemented to support enhanced engine braking applications, such as 2-stroke or 1.5-stroke engine braking implementations where the intake flow path may be exposed to excessive transient pressures in the combustion chamber during activation or deactivation of an engine brake. Intake throttle, exhaust gas recirculation (EGR) valve, intake manifold blow-off valve, compressor bypass valve, exhaust throttle, turbocharger geometry or turbocharger waste gate may be controlled to effectuate counter flow management separately or in combination. Excessive transient conditions may also be prevented or managed by sequential valve motion in which brake motion activation occurs first and then exhaust valve main event deactivation occurs second. Delay between brake activation and main event deactivation may be facilitated using mechanical and/or hydraulic implements as well as electronically.