Turbocharged Engine Braking With Dual Closed-Loop Pressure Control
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Solution Overview
Problem
Existing engine brake systems for turbocharged engines suffer from limited braking power, secondary effects like overheating of fuel injector tips, and slow response times, particularly when using exhaust gas restriction devices or variable geometry turbochargers.
Innovation Solution
A dual-phase engine brake method that simultaneously regulates exhaust and boost pressures in closed loops using an exhaust gas restriction device and boost pressure regulation device, maintaining a positive pressure differential and higher air flow to enhance braking power and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If exhaust gas restriction device closes the flap to increase exhaust back-pressure, then engine brake power is improved, but air flow through the engine decreases causing overheating of injector tips and increased oil rejection
Solution Approach 1:
The patent changes the control parameters from single-parameter exhaust back-pressure control to dual-parameter control (exhaust back-pressure and boost pressure). By independently regulating both parameters, the system can maintain high exhaust back-pressure for braking while simultaneously maintaining adequate boost pressure for cooling airflow, thus resolving the contradiction between braking power and injector cooling.
Solution Approach 2:
The patent segments the control functions into two independent control loops: one for exhaust back-pressure regulation and another for boost pressure regulation. This segmentation allows each parameter to be optimized independently, enabling the system to achieve high braking power while maintaining sufficient air flow for cooling the injector tips.
2Power
If exhaust gas restriction device closes the flap to increase exhaust back-pressure, then engine brake power is improved, but air pressure in compressor housing decreases causing increased oil rejection
Solution Approach 1:
The patent introduces a second control parameter (boost pressure) in addition to exhaust back-pressure. By maintaining adequate boost pressure through the boost pressure regulation device, the system ensures sufficient air pressure in the compressor housing to keep the seal tight, thereby preventing oil rejection while still achieving high exhaust back-pressure for effective braking.
Solution Approach 2:
The patent segments the control system into two independent loops that can operate simultaneously. The exhaust back-pressure control loop maximizes braking power, while the boost pressure control loop maintains adequate pressure to prevent oil rejection, thus resolving the contradiction between these two objectives.
3Quantity of substance
If VGT is used to control exhaust back-pressure instead of exhaust flap, then air flow increases improving compression release system efficiency, but difference between intake pressure and exhaust pressure decreases reducing braking power
Solution Approach 1:
The patent segments the pressure control functions into two independent loops. By using both VGT and exhaust flap together with separate control strategies, the system can maintain a larger pressure differential for braking while still benefiting from improved air flow, thus resolving the contradiction between these two competing objectives.
Solution Approach 2:
The patent merges two control devices (VGT and exhaust flap) that were previously used alternatively into a combined system. By coordinating both devices through dual closed-loop control, the system achieves both improved air flow from VGT and maintained pressure differential from exhaust flap, simultaneously achieving high braking power and good compression release efficiency.
4Productivity
If VGT is used to control exhaust back-pressure, then compression release system efficiency is improved, but response time increases becoming slow and sluggish
Solution Approach 1:
The patent segments the control response into two independent channels. The exhaust flap control provides rapid response for immediate braking power adjustment, while the VGT control optimizes air flow and compression release efficiency. This segmented control strategy allows the system to achieve both fast response and high efficiency without the sluggishness of VGT-only control.
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
The method achieves higher engine brake power, maintains injector tip cooling, and prevents oil leaks, enabling safer operation on steep downhill roads without using foundation brakes.
Implementation Method 1
a turbocharger; with a compressor driven by a turbine, the compressor being configured to increase a boost pressure of the fresh air in the intake manifold, while the turbine is configured to be driven by the exhaust air flowing from the exhaust manifold
Implementation Method 2
the compressor being configured to increase a boost pressure of the fresh air in the intake manifold
Implementation Method 3
the pressure differential between boost pressure and air exhaust pressure remains positive, preventing oil leaks through the compressor seal
Implementation Method 4
the air flow through the cylinders remains at a higher level, contributing to the cooling of the injector tips
Data Source
AI summary
An engine brake method is for operating a vehicle with a turbocharged internal combustion engine. The engine comprises a boost pressure regulation device, which is configured to adjust the boost pressure in the intake manifold, and an exhaust gas restriction device, which is located downstream from a turbine of the turbocharger and which is configured to regulate an air exhaust pressure in an exhaust manifold. The engine brake method includes a dual phase during which, simultaneously, the boost pressure regulation device regulates the air exhaust pressure in the exhaust manifold in closed loop, and the exhaust gas restriction device controls the boost pressure in closed loop.