Turbocharger Control Method for Sonic Block Prevention
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Solution Overview
Problem
Existing turbocharger supercharging systems for internal combustion engines face challenges in maintaining the operating range within a useful area to avoid destructive conditions near the saturation line, where high speeds can lead to sonic block and damage, while existing control methods either prevent damage but not optimize performance or fail to limit maximum rotation speed effectively.
Innovation Solution
A control method using an electronic control unit that determines and maintains operating limit curves and intervening curves for the wastegate and Poff valves to restrict the turbocharger's target pressure and rotation speed, ensuring the operating range remains within a useful area without reaching sonic conditions, utilizing sensors for temperature, pressure, and crankshaft position to adjust valve operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the turbocharger operates near the saturation line to maximize power output, then the volumetric efficiency and power generation are improved, but the risk of reaching sonic block and causing damage increases
Solution Approach 1:
The control method performs preliminary determination of operating limit curves and intervening curves based on compressor characteristics before actual operation. These curves are pre-calculated and stored, allowing the control system to proactively prevent operation in dangerous zones rather than reacting after damage occurs. The electronic control unit uses these pre-determined curves to limit target pressure and rotation speed before sonic block conditions can develop.
Solution Approach 2:
The control method implements continuous feedback by monitoring actual turbocharger operation against the pre-determined operating limit curves and intervening curves. The electronic control unit adjusts wastegate valve positioning and compressor bypass valve positioning based on real-time measurements of mass flow rate, pressure, and temperature, ensuring the system remains within safe operating boundaries while maximizing performance. This closed-loop control dynamically responds to changing engine conditions.
2Reliability
If existing control methods limit the maximum rotation speed to prevent damage, then the turbocharger reliability is improved, but the performance optimization is lost
Solution Approach 1:
The control method dynamically adjusts operating limits based on real-time engine conditions rather than using fixed speed limits. The electronic control unit continuously calculates the appropriate operating point by considering current mass flow rate, pressure, temperature, and engine load conditions. This allows the system to operate near the saturation line when conditions permit maximum performance while automatically retreating to safer operating points when conditions approach dangerous thresholds, achieving both reliability and performance optimization.
Solution Approach 2:
The control method changes multiple parameters simultaneously including wastegate valve positioning, compressor bypass valve positioning, target pressure, and rotation speed limits. Rather than simply capping rotation speed, the system adjusts the entire operating envelope by modifying pressure targets and flow rate limits based on the pre-determined curves. This multi-parameter control allows the turbocharger to operate closer to its performance limits while maintaining safety margins.
3Reliability
If the operating range is restricted to avoid the pumping line and saturation line, then the turbocharger is protected from damage, but the useful operating area is reduced
Solution Approach 1:
The control method pre-determines operating limit curves and intervening curves that define the maximum safe operating boundaries based on compressor characteristics. These curves are calculated beforehand and stored in the electronic control unit, allowing the system to know exactly where the safe operating area ends and dangerous zones begin. This preliminary preparation enables the system to operate as close to the safety boundaries as possible without entering dangerous regions.
Solution Approach 2:
The control method uses intervening curves that are positioned between the operating limit curves and the actual saturation line/pumping line boundaries. This creates a buffer zone that provides safety margins while still allowing operation much closer to the maximum performance boundaries than traditional conservative limits would permit. The system applies partial limitation through the wastegate and bypass valves to maintain operation within this optimized envelope.
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 method effectively keeps the turbocharger within a safe operating range near the saturation line without reaching sonic block, preventing damage and maintaining performance, with a simple and cost-effective implementation that does not require additional components or high computing power.
Implementation Method 1
a compressor, which is put in rotation by the turbine and is arranged along the air supply conduit compressing the intake air from the engine
Implementation Method 2
a turbine, which is arranged along an exhaust conduit to rotate at high speed under the pressure of exhaust gases expelled from the engine
Implementation Method 3
utilizing sensors for temperature, pressure, and crankshaft position to adjust valve operations
Implementation Method 4
utilizing sensors for temperature, pressure, and crankshaft position to adjust valve operations
Data Source
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AI summary
A method for controlling an internal combustion engine (1) supercharged by means of a turbocharger (12) provided with a turbine (13) and a compressor (14); the control method comprises the steps of determining the current reduced mass flow rate (QAHR) of the compressor 14; determining a safety threshold (Mmax_turbo) of the reduced mass flow rate (QAHR), said safety threshold (Mmax_turbo) delimits in the plane reduced mass flow rate / compression ratio the portion of the critical area closest to achieve sonic conditions; and imposing that the reduced mass flow rate (QAH) of the compressor 14 is lower than the safety threshold (Mmax_turbo) of the reduced mass flow rate (QAHR).