Hybrid Vehicle EHC Current Sensor Failure Detection
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Solution Overview
Problem
Existing hybrid vehicles face challenges in detecting failures of electrically heated catalyst (EHC) current sensors without increasing equipment costs or complexity, which can lead to inadequate exhaust gas purification or overheating issues.
Innovation Solution
A hybrid vehicle system that uses a second current sensor to estimate the current supplied to the EHC and compares it with the detection value from the first current sensor, allowing for failure determination without making the first current sensor redundant, thereby maintaining efficient exhaust gas purification and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the EHC current sensor is made redundant to detect sensor failure, then the reliability of failure detection is improved, but the device complexity and cost increase
Solution Approach 1:
The patent introduces a current estimation mechanism that acts as an intermediary to indirectly determine EHC current sensor failures. Instead of using a redundant sensor, the system estimates the EHC current by measuring the output current of the electric storage device and subtracting the current to the inverter, providing a reference value for failure detection without adding physical sensors
Solution Approach 2:
The patent replaces the mechanical/electrical solution of adding a redundant physical sensor with a computational approach. The controller uses calculation and data processing to estimate the EHC current and detect sensor failures, substituting physical redundancy with informational redundancy through mathematical relationships
2Reliability
If the EHC current sensor indicates a value higher than the actual current, then the exhaust gas purification performance is maintained, but the electric power supply to the EHC becomes deficient
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the relationship between the EHC current sensor output and the estimated EHC current. When a discrepancy is detected indicating sensor failure, the controller can adjust the EHC power supply control to compensate, ensuring the EHC receives adequate power for proper exhaust gas purification
3Power
If the EHC current sensor indicates a value lower than the actual current, then the electric power supply to the EHC becomes excessive, but overheated areas form locally causing cracks
Solution Approach 1:
The feedback mechanism allows the controller to detect when the EHC current sensor is providing erroneously low readings. Upon detecting this failure mode, the controller can reduce or adjust the EHC power supply to prevent excessive heating that would cause local overheating and potential cracks in the catalyst structure
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 approach enables the detection of EHC current sensor failures without the need for redundant sensors, ensuring effective exhaust gas purification and preventing overheating, thus maintaining the vehicle's performance and cost-effectiveness.
Implementation Method 1
an electrically heated catalyst device configured to be supplied with electric power from the electric storage device to electrically heat the catalyst
Data Source
AI summary
An electrically heated catalyst device has a catalyst that purifies exhaust gas from an engine, and is configured to heat the catalyst with electric power that is supplied from an electric storage device. A current sensor detects a current that is supplied to the electrically heated catalyst device. A current sensor detects an input/output current of the electric storage device. A controller executes failure determination control to determine whether the current sensor has a failure. In the failure determination control, the controller estimates a current that is supplied to the electrically heated catalyst device using a detection value of the current sensor and compares the estimated current with a detection value of the current sensor to determine whether the current sensor has a failure.