Manifold Pressure Sensor Offset Determination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Engine systems without a barometric pressure (BP) sensor face challenges in accurately estimating BP, especially at throttle angles below a threshold, leading to reduced accuracy in engine control, and MAP sensor degradation or offset issues cannot be effectively addressed without additional pressure sensors.
Innovation Solution
The method estimates BP using a ratio between MAP sensor readings at different altitudes and throttle angles, adjusting the MAP sensor output based on calculated offsets, and indicates sensor degradation when the offset exceeds a threshold, thereby improving accuracy in engine control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MAP sensor readings are used directly without offset correction, then the system is simple and requires no additional sensors, but the engine control accuracy deteriorates due to sensor degradation and offset
Solution Approach 1:
The MAP sensor system performs self-diagnosis and self-correction by using its own readings at different throttle angles to calculate offset and barometric pressure, eliminating the need for external reference sensors while maintaining accuracy
Solution Approach 2:
The system changes the operating parameter (throttle angle) to obtain multiple MAP readings, then uses these varying readings to calculate offset and barometric pressure corrections, transforming a single-parameter measurement into a multi-parameter diagnostic system
2Reliability
If additional pressure sensors are added to detect MAP sensor degradation, then sensor offset can be detected, but the device complexity and cost increase
Solution Approach 1:
The single MAP sensor monitors its own health by comparing readings taken at different throttle angles, calculating offset values that indicate degradation without requiring any additional reference pressure sensors
Solution Approach 2:
The MAP sensor serves multiple functions: it measures manifold pressure for engine control, calculates barometric pressure for altitude compensation, and performs self-diagnosis for offset detection, eliminating the need for separate dedicated sensors
3Ease of operation
If barometric pressure is estimated at low throttle angles, then engine control can be maintained, but accuracy deteriorates due to insufficient pressure differential
Solution Approach 1:
The system performs preliminary calibration at wide-open throttle where pressure differential is sufficient, storing offset and barometric pressure values that are then applied during low throttle angle operation to maintain accuracy
Solution Approach 2:
The throttle angle acts as an intermediary parameter that enables the system to select appropriate measurement strategies: using direct MAP readings when throttle angle is high, and using stored calibration data when throttle angle is low
Data Source
AI summary
Methods and systems are provided for determining an offset of a manifold pressure sensor. In one example, an engine method may include indicating degradation of the manifold pressure sensor based on a sensor offset, the sensor offset based on a manifold pressure measured at a first throttle angle, a barometric pressure at a second throttle angle, a reference manifold pressure at the first throttle angle and reference barometric pressure, and the reference barometric pressure. Further, the method may include adjusting an output of the manifold pressure sensor by the determined sensor offset.