Ambient Pressure Determination via Charge Pressure Transient Analysis
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Solution Overview
Problem
Turbocharged engines face challenges in determining ambient air pressure continuously without additional sensors, especially under varying conditions like driving uphill, as existing methods fail to establish a reliable mathematical or physical relationship between intake manifold pressure and ambient pressure, leading to increased costs and potential engine control issues.
Innovation Solution
A method that determines ambient pressure by analyzing the transient profile of charge pressure during a negative load step, using a charge-pressure sensor and an exponential equation to calculate the current ambient pressure, eliminating the need for a separate ambient pressure sensor, and utilizing a recirculation valve to bypass the charger and throttle valve for data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an additional ambient pressure sensor is installed to continuously measure ambient pressure, then measurement precision and reliability are improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The charge pressure sensor is made multi-functional by using it for both charge pressure measurement and ambient pressure determination. The sensor serves dual purposes: monitoring charge pressure for engine control and providing data for calculating ambient pressure through the exponential relationship during negative load steps, eliminating the need for a separate ambient pressure sensor
Solution Approach 2:
The system uses its own existing sensor (charge pressure sensor) and operating conditions (negative load steps) to determine ambient pressure without external assistance. The engine's natural transient behavior during load reduction is utilized as a self-contained method to extract ambient pressure information from charge pressure measurements
2Device complexity
If ambient pressure is determined from intake manifold pressure in a turbocharged engine, then device complexity is reduced, but measurement precision deteriorates due to lack of mathematical relationship
Solution Approach 1:
The system performs preliminary action by inducing a negative load step (throttle closure) to create a specific operating condition where the exponential relationship between charge pressure and ambient pressure becomes valid. This preparatory maneuver establishes the mathematical foundation needed for accurate ambient pressure calculation
Solution Approach 2:
The system changes operating parameters by transitioning to a negative load step condition, which alters the pressure relationships in the induction tract. During this transient state, the charge pressure exponential decay follows a predictable pattern that reveals ambient pressure, transforming an otherwise unusable operating condition into a measurement opportunity
3Device complexity
If ambient pressure is determined only with engine stationary, then device complexity is reduced, but productivity deteriorates due to inability to track rapid pressure changes
Solution Approach 1:
The system uses periodic negative load steps (throttle closures) as trigger events to perform ambient pressure determination. By utilizing these recurring transient events during normal operation, the system continuously updates ambient pressure at appropriate intervals without requiring dedicated measurement phases or engine idle conditions
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
Enables continuous determination of ambient pressure without additional sensors, improving engine control and reducing manufacturing costs by leveraging existing charge-pressure sensor data and algorithmic calculations, allowing for precise correction values during driving conditions.
Implementation Method 1
the charge-pressure sensor detecting a charge pressure generated by the charger
Implementation Method 2
measuring the charge pressure and recording the transient profile of the charge pressure and determining a value of a current ambient pressure from the transient profile of the charge-pressure
Data Source
AI summary
In turbocharged engines, there is the problem that, in particular under load, the ambient pressure (AMP) cannot be determined directly from the measurement values of a charge-pressure sensor (8). In order to avoid the installation of a further pressure sensor which is suitable for the detection of the ambient pressure (AMP), it is proposed that, during a negative load step of the internal combustion engine in which a switch takes place from supercharged engine operation into non-supercharged engine operation, the charge-pressure sensor (8) measures the transient profile of the charge pressure (PUT). A value for the ambient pressure (AMP) is determined from the transient profile of the charge pressure (PUT). Through the pressure value for the present ambient pressure (AMP), it is possible to optimize the engine operation for example when travelling up a slope.