Variable Geometry Turbocharger Transient Control
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Solution Overview
Problem
Turbocharged engines experience delayed torque response due to the inertia of the rotating assembly and insufficient engine flow rates at low speeds, particularly during transient phases of high acceleration, leading to reduced engine performance and increased emissions.
Innovation Solution
A method for controlling a turbocharger with a variable geometry compressor that adjusts its geometry based on two distinct maps: one for stabilized operation and another for transient operation, with progressive switching between the two maps based on engine speed and torque levels, allowing for greater fin opening during transient phases to enhance acceleration capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the turbocharger uses a single geometry configuration optimized for stabilized operation, then the compressor efficiency is optimized for steady-state performance, but the response time during transient phases is delayed
Solution Approach 1:
The compressor geometry is made dynamically adjustable through variable stator vanes that can change their angle according to operating conditions. The system uses two distinct maps (first map for stabilized operation, second map for transient operation) that provide different vane angle settings based on whether the engine is in steady-state or transient conditions, allowing the geometry to adapt dynamically to optimize both response time and efficiency
Solution Approach 2:
The invention changes the geometric parameters of the compressor by switching between two predefined maps of adjustment values. The first map provides geometry settings optimized for stabilized operation, while the second map provides settings optimized for transient operation. The system detects transient conditions and switches between these parameter sets to optimize performance for the current operating phase
2Object-generated harmful factors
If the turbocharger geometry is optimized for stabilized operation, then emissions are reduced during steady-state phases, but engine performance is reduced during transient acceleration phases
Solution Approach 1:
The variable geometry compressor allows the system to dynamically switch between emission-optimized geometry (first map for stabilized operation) and performance-optimized geometry (second map for transient operation). This dynamic adaptation ensures that emissions are minimized during steady-state cruising while engine performance is maximized during transient acceleration phases
Solution Approach 2:
The system changes geometric parameters based on operating conditions by selecting from two maps. The first map provides geometry settings that reduce emissions during stabilized operation, while the second map provides settings that enhance engine performance during transient phases. The control system monitors operating conditions and switches between these parameter sets accordingly
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 approach improves the turbocharger's efficiency and response time during transient phases, enhancing vehicle acceleration and reducing emissions by optimizing compressor performance and supercharging pressure.
Implementation Method 1
A turbocharger is made up of a turbine and a compressor driven in rotation by the turbine, through a shaft connecting the turbine to the compressor. The turbine is arranged in an exhaust circuit of the engine in the path of the exhaust gases and is driven in rotation by the exhaust gases.
Implementation Method 2
The compressor is disposed in an intake circuit on the air intake path into the engine. It compresses the air injected into the engine, allowing the engine to be boosted compared to an intake speed at atmospheric pressure.
Data Source
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AI summary
The invention relates to a method for controlling a variable-compressor-geometry turbocharger, in which the boost pressure is controlled by setting the geometry of the compressor according to a first map (C1) of set values, corresponding to an optimised performance of the compressor during the steady-state operation of the engine. According to the invention, the transient operation of the engine is detected and the geometry setting of the compressor is modified according to a second map (C2), corresponding to an optimised performance of the compressor during the transient operation of the engine, and the setting is switched gradually from the second map to the first map, by means of the detection of the evolution over time of the torque produced by the engine relative to a maximum torque level obtained when the engine speed is steady.