Engine Braking Throttle Flap Dynamics
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Solution Overview
Problem
Existing engine braking methods for diesel engines, while effective, require additional measures to enhance braking action, leading to complex systems and unfavorable response behavior due to reliance on exhaust-gas counter-pressure control.
Innovation Solution
A method and device for engine braking that utilizes a throttling device and bypass line to regulate exhaust-gas counter-pressure and charge air pressure, allowing for increased braking action by optimizing the position of the throttling device based on measured pressures, thereby achieving improved response behavior and increased braking efficiency across various engine rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If additional measures are taken to raise charge air pressure during engine braking mode, then braking action is increased, but device complexity increases
Solution Approach 1:
The throttle flap is designed to be dynamically controllable with at least two distinct positions: a first position for standard exhaust gas flow and a second position for engine braking mode. This dynamic positioning allows the system to achieve increased braking action through a single, relatively simple component rather than requiring multiple complex devices.
Solution Approach 2:
The system changes the flow resistance parameter of the exhaust gas tract by repositioning the throttle flap between two positions. This parameter change enables the same physical component to deliver different performance levels (standard operation vs. enhanced braking) without adding device complexity.
2Productivity
If exhaust-gas counter-pressure control is used to enhance braking action, then braking efficiency is improved, but response behavior becomes unfavorable
Solution Approach 1:
The throttle flap is repositioned to the second position in advance, before the engine braking mode is fully activated. This preliminary action of opening the throttle flap creates a restricted exhaust path that immediately generates high counter-pressure when braking is initiated, resulting in faster response behavior and improved braking efficiency.
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 solution provides enhanced engine braking action with improved regulation and reduced component complexity, allowing for higher exhaust-gas counter-pressures and faster pressure increases, effectively relieving load from other braking systems and ensuring effective braking at low rotational speeds.
Implementation Method 1
at least one exhaust-gas turbocharger having an exhaust-gas turbine acted on by an exhaust-gas flow and having a charge air compressor
Implementation Method 2
the exhaust-gas flow being throttled and a pressure increase in the exhaust gas thus being generated upstream of the device for throttling the exhaust-gas flow
Data Source
AI summary
A method for engine braking of an engine which has at least one exhaust-gas turbocharger with an exhaust-gas turbine acted on by an exhaust-gas flow and a charge air compressor. A device for throttling exhaust-gas flow is arranged between exhaust outlet valves and the exhaust-gas turbocharger, and a bypass line conducts the exhaust-gas flow past the throttling device, the exhaust-gas flow being conducted through the at least one bypass line to a turbine wheel of the exhaust-gas turbine. An exhaust gas counter-pressure and a charge air pressure are measured. Based on the measurement, an optimum position of the throttling device to obtain a predetermined braking action is determined. The exhaust-gas counter-pressure and the charge air pressure are subsequently controlled by adjusting the throttling device corresponding to the determination of the optimum position of the throttling device.