Turbo Speed Estimation Using MAP Sensor Pressure Modeling
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Solution Overview
Problem
Existing methods for estimating turbocharger speed are costly and unreliable due to the need for a compressor outlet pressure sensor, which is often absent in contemporary engine designs, leading to potential mechanical damage and engine failure.
Innovation Solution
Estimate turbocharger speed using data from a Manifold Absolute Pressure (MAP) sensor located downstream of the throttle valve, utilizing a controller that processes signals from compressor air flow, inlet pressure, intake manifold pressure, and throttle position to calculate compressor outlet pressure and turbocharger speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a compressor outlet pressure sensor is used to estimate turbo speed, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a charge air cooler temperature sensor as an intermediary element to indirectly measure compressor outlet conditions. By measuring the temperature of charge air after cooling, the system can back-calculate compressor outlet temperature and pressure, thereby estimating turbo speed without requiring a direct pressure sensor at the compressor outlet.
Solution Approach 2:
The patent creates a thermal model that copies the thermodynamic relationships occurring in the compressor and charge air cooler. This model uses readily available sensor data (intake manifold pressure, air flow, temperatures) to replicate the compressor outlet conditions mathematically, providing an indirect but accurate measurement of turbo speed.
2Measurement precision
If a compressor outlet pressure sensor is installed, then turbo speed estimation accuracy is improved, but system reliability decreases
Solution Approach 1:
The charge air cooler temperature sensor serves as a more reliable intermediary measurement point. Since this sensor is located downstream in the charge air system rather than at the compressor outlet, it is less susceptible to harsh environmental conditions, vibration, and mechanical failures that plague direct compressor outlet sensors.
Solution Approach 2:
The system uses existing sensors (charge air cooler temperature, intake manifold pressure, air flow sensors) that are already part of the engine management system to self-determine compressor outlet conditions through thermodynamic modeling, eliminating the need for additional dedicated sensors and their associated failure modes.
3Device complexity
If existing sensors are used to estimate turbo speed, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent transforms readily available sensor parameters (intake manifold pressure, air flow rate, charge air cooler temperature) into compressor outlet conditions through thermodynamic parameter transformations. By applying thermodynamic relationships and accounting for charge air cooler performance, the system derives compressor outlet temperature and pressure with high precision from common sensor data.
Solution Approach 2:
The thermodynamic model creates a virtual copy of the compressor outlet conditions using mathematical relationships. This computational copying allows the system to access compressor outlet pressure and temperature information indirectly through a chain of thermodynamic calculations based on measurable parameters throughout the intake system.
Data Source
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AI summary
The speed of a turbocharger may be estimated using data from sensors that are readily available in most engine management systems. In some cases, a pressure measurement from a MAP sensor may be used, in combination with one or more computational models, to provide an efficient, lower cost estimate of turbo speed that can be used to control operation of the engine and/or the turbocharger.