Exhaust Manifold Temperature Estimation via Downstream Sensor Correction
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Solution Overview
Problem
Conventional methods for determining the exhaust manifold temperature upstream of a turbine in turbocharged engines are slow, inaccurate, and costly, due to the reliance on temperature sensors that are affected by soot and exhaust gases, and require multiple sensors for accurate measurement.
Innovation Solution
A method using a phenomenological/combustion-based model to estimate the exhaust manifold temperature, corrected by measurements downstream of the turbine, thereby reducing the need for additional sensors and improving accuracy and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is used to measure the exhaust manifold temperature upstream of the turbine, then the temperature can be measured, but the measurement is slow with time constants of 1-2 seconds and can take up to 10 seconds to reach steady state
Solution Approach 1:
The patent replaces the direct mechanical/physical temperature sensor measurement in the exhaust manifold with a model-based estimation approach. The system uses a thermal model of the turbocharger and exhaust system, combined with measurements from a temperature sensor located downstream of the turbine and other available sensor data (pressure, mass flow), to calculate the upstream temperature T3. This substitution eliminates the need for a fast-responding sensor in the harsh upstream environment while providing accurate, real-time temperature estimates.
2Speed
If the T3 sensor element opening is enlarged to improve response time, then the response is faster, but soot and exhaust gases reduce the accuracy and durability of the sensor
Solution Approach 1:
The patent extracts the temperature sensor from the harsh upstream exhaust manifold environment (where T3 is measured) and relocates it to a downstream position after the turbine. The system then uses a thermal model to back-calculate the upstream temperature from the downstream measurement. This extraction protects the sensor from soot accumulation and thermal damage while maintaining measurement capability through mathematical modeling.
Solution Approach 2:
The patent introduces a thermal model as an intermediary between the downstream temperature sensor and the upstream temperature calculation. The model acts as a bridge that translates the downstream measurement (T4) and other system parameters into an accurate estimate of the upstream temperature (T3), eliminating the need for direct sensor exposure to the harsh upstream environment.
3Measurement precision
If multiple temperature sensors are used to account for variations in exhaust conditions, then measurement accuracy improves, but system complexity and cost increase
Solution Approach 1:
The patent makes the downstream temperature sensor multi-functional by using it not only for its primary measurement purpose but also as the basis for calculating upstream temperature through the thermal model. This single sensor serves dual functions, eliminating the need for separate upstream temperature sensors and reducing overall system complexity while maintaining measurement accuracy.
Solution Approach 2:
The patent changes the measurement parameter location from upstream (T3) to downstream (T4) of the turbine, and uses mathematical transformation through the thermal model to obtain the desired upstream temperature. This parameter transformation approach allows accurate upstream temperature determination using a single downstream sensor, avoiding the need for multiple physical sensors.
4Reliability
If pre-turbine temperatures are limited to steady state limits of 820-850°C for turbo protection, then the turbocharger is protected from thermal damage, but the engine cannot operate closer to the turbo limit to extract more power
Solution Approach 1:
The patent transitions from static, conservative steady-state temperature limits to a dynamic temperature estimation and control approach. The thermal model continuously updates the upstream temperature estimate based on current operating conditions, allowing the control system to dynamically adjust engine operation to maximize power output while staying within safe thermal limits of the turbocharger, rather than operating below the limits due to measurement uncertainty.
Data Source
AI summary
The disclosure relates to a method and an observer for determining the exhaust manifold temperature in a turbocharged engine upstream of the turbine. In one example, a method for determining an exhaust manifold temperature in a turbocharged engine, the engine including a turbocharger and a turbine and the exhaust manifold temperature including a temperature upstream of the turbine, the method comprises estimating a value of the exhaust manifold temperature based on a model, measuring a temperature downstream of the turbine, and correcting the value of the exhaust manifold temperature based on the measurement.