Cylinder Pressure Sensor Gain and Offset Diagnostics
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Solution Overview
Problem
Current engine systems do not assess the gain and offset of cylinder pressure sensors before using their feedback in control strategies, which can significantly impact fuel economy, emissions, and durability.
Innovation Solution
An apparatus and method that includes a sensor module to acquire cylinder pressure data, an offset diagnostic module to determine the sensor offset by comparing actual and reference pressures, and a notification module to alert for offsets exceeding a threshold, along with a system that uses a controller to determine and compare sensor gains and offsets, providing error notifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cylinder pressure sensor feedback control is implemented without prior gain and offset assessment, then engine control performance is improved, but measurement precision deteriorates due to uncalibrated sensor readings
Solution Approach 1:
The patent performs gain and offset assessment of the cylinder pressure sensor before implementing feedback control. The ECU determines reference pressures during specific engine conditions (crankshaft not rotating, keyed on) and compares them with actual sensor readings to calculate offset values. This preliminary calibration ensures measurement precision is established before the sensor data is used for engine control, resolving the contradiction between improving control performance and maintaining measurement accuracy.
2Measurement precision
If on-board diagnostic procedures are added to assess sensor gain and offset, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-diagnostic capability where the ECU automatically performs gain and offset assessment using the cylinder pressure sensor itself and existing engine operational data. The system determines reference pressures based on engine conditions (keyed on state, crankshaft rotation status) and autonomously calculates calibration parameters without requiring external diagnostic equipment. This self-service approach improves measurement precision while avoiding additional hardware complexity.
3Ease of operation
If sensor offset is not corrected, then ease of operation is maintained, but reliability deteriorates due to inaccurate feedback control
Solution Approach 1:
The patent establishes a feedback loop where the ECU continuously monitors cylinder pressure sensor readings, compares them against determined reference pressures, and identifies offset errors. The system provides notifications when offset exceeds thresholds and can apply corrections to the sensor data. This feedback mechanism ensures reliability of feedback control by maintaining accurate measurements while preserving ease of operation through automated correction processes that require no manual intervention.
Data Source
AI summary
An apparatus includes a sensor module, an offset diagnostic module, and a notification module. The sensor module is in operative communication with a cylinder pressure sensor and structured to acquire cylinder pressure data from the cylinder pressure sensor indicative of an actual in-cylinder pressure of a cylinder of an engine. The offset diagnostic module is structured to interpret the cylinder pressure data to determine an offset of the cylinder pressure sensor based on a reference in-cylinder pressure and the actual in-cylinder pressure. The notification module is structured to provide an offset error notification responsive to the offset being greater than a threshold offset.