Hybrid Vehicle O2 Sensor Failure Determination via Motoring
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Solution Overview
Problem
Existing failure determination methods for detection units in hybrid vehicle exhaust systems are limited in the travel mode where the engine generates electric power and only an electric motor drives the wheels, as they cannot efficiently perform various failure determination methods.
Innovation Solution
A failure determination device that temporarily stops fuel supply to the engine and uses the motor generator for motoring, allowing failure determination based on detection values before and after fuel supply restart, enabling both rich-to-lean and lean-to-rich exhaust gas failure determinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If various failure determination methods are performed in the travel mode, then the reliability of detection unit monitoring is improved, but the time required for determination and electric power loss increase
Solution Approach 1:
The system performs failure determination by periodically switching fuel supply on and off during motoring operation. The control unit executes multiple determination cycles with alternating fuel supply states (on-state and off-state) to enable both rich-to-lean and lean-to-rich failure determination methods, allowing comprehensive detection within a single motoring period rather than requiring separate dedicated periods for each method.
2Reliability
If various failure determination methods are performed in the travel mode, then the reliability of detection unit monitoring is improved, but the electric power loss increases
Solution Approach 1:
The system merges multiple failure determination methods (rich-to-lean determination and lean-to-rich determination) into a single integrated process during motoring operation. By combining both determination approaches in one continuous motoring phase with alternating fuel supply states, the system achieves comprehensive detection coverage without requiring separate motoring periods for each method, thereby reducing total electric power consumption.
Solution Approach 2:
The motoring operation serves multiple functions simultaneously: it enables both rich-to-lean failure determination and lean-to-rich failure determination, while also maintaining engine readiness. The single motoring phase performs what would traditionally require multiple separate operations, making the system more efficient in terms of electric power usage.
3Measurement precision
If fuel supply is stopped and motoring is performed for failure determination, then the detection accuracy is improved, but the productivity of the travel mode decreases
Solution Approach 1:
The system dynamically adjusts the fuel supply state during motoring operation to optimize both detection accuracy and travel efficiency. The control unit switches fuel supply between on and off states in a controlled sequence, allowing the engine to operate in different conditions (rich and lean) necessary for accurate detection, while minimizing the total duration of motoring to preserve travel productivity.
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 allows for comprehensive failure determination of detection units in the travel mode, reducing the time required for determination and minimizing electric power loss by performing all necessary failure determination methods efficiently.
Implementation Method 1
a motor generator that is driven by the engine to generate electric power, and drives the engine using electric power supplied from a driving battery
Data Source
AI summary
In a hybrid vehicle that selects a series mode in which an engine drives a motor generator to generate electric power and a driving motor drives drive wheels, the series mode is suspended to temporarily stop fuel supply to the engine, and the motor generator forcedly drives the engine using electric power supplied from a driving battery to perform motoring, and failure determination of the O2 sensors is performed based on oxygen concentrations of an exhaust gas from the engine detected by a front O2 sensor and a rear O2 sensor when the fuel supply to the engine is stopped and when the fuel supply is restarted after finish of the motoring.