Abnormality Diagnosis for Multi-Injector Engines
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Solution Overview
Problem
Existing internal combustion engine systems with multiple injectors per cylinder face challenges in diagnosing which injector is abnormal, leading to unnecessary replacement of both injectors, increasing time and cost.
Innovation Solution
An abnormality diagnosis device that performs injection ratio changing control between multiple injectors while keeping the sum of command injection quantities constant, using an exhaust gas sensor to specify the abnormal injector by evaluating output changes in the air-fuel ratio and torque feedback, and includes a failsafe mechanism to prevent drivability deterioration and ensure fuel injection continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple injectors are provided for each cylinder to improve fuel atomization and mixture formation, then fuel injection performance is improved, but the ability to identify which specific injector is abnormal deteriorates
Solution Approach 1:
The patent segments the fuel injection function by providing multiple injectors (first and second injectors) for each cylinder, each responsible for a portion of the fuel injection. This segmentation improves fuel atomization and mixture formation while enabling individual identification of abnormal injectors through separate control and measurement of each injector's fuel injection quantity, resolving the contradiction between improved injection performance and difficulty in detecting which specific injector is abnormal
Solution Approach 2:
The patent implements feedback mechanisms by measuring the actual fuel injection quantity of each individual injector and comparing it with the command injection quantity. The air-fuel ratio sensor provides feedback on the overall mixture quality, which is then used to calculate learning values that indicate abnormality in specific injectors. This feedback system enables precise identification of abnormal injectors while maintaining the benefits of multiple injectors per cylinder
2Measurement precision
If conventional air-fuel ratio sensor-based diagnosis is used to identify abnormal cylinders, then abnormal cylinder detection is achieved, but the specific abnormal injector within the cylinder cannot be identified
Solution Approach 1:
The patent segments the diagnostic process by separately measuring and analyzing the fuel injection quantity of each individual injector (first injector and second injector) within a cylinder. By controlling and measuring each injector independently and comparing actual injection quantities with command quantities, the system can identify which specific injector is abnormal, preventing the loss of injector-specific diagnostic information while maintaining accurate abnormal cylinder detection
Solution Approach 2:
The patent changes the diagnostic approach by introducing learning values that represent the difference between command injection quantities and actual injection quantities for each individual injector. These learning values serve as new diagnostic parameters that preserve injector-specific information, enabling identification of the specific abnormal injector rather than just detecting abnormal cylinders
3Reliability
If both injectors of an abnormal cylinder are replaced to ensure reliability, then engine reliability is improved, but replacement time and part costs increase
Solution Approach 1:
The patent enables the diagnostic system to automatically identify and specify which individual injector is abnormal through comparison of command injection quantities with actual injection quantities and calculation of learning values. This self-service diagnostic capability eliminates the need for technicians to replace both injectors as a precaution, allowing replacement of only the specifically identified abnormal injector, thereby reducing replacement time and part costs while maintaining engine reliability
Data Source
AI summary
A cylinder causing an abnormal air-fuel ratio is specified. Injection ratio changing control for gradually changing a ratio between command injection quantities of two injectors of the abnormal cylinder while keeping the sum of the command injection quantities of the two injectors constant is performed on the abnormal cylinder. If the injection ratio changing control is performed under the same condition, a changing behavior of the actual sum injection quantity of the two injectors varies and a changing behavior of the air-fuel ratio varies depending on which one of the two injectors is abnormal. Therefore, the abnormal injector out of the two injectors is specified using a learning value of an air-fuel ratio feedback correction value based on an output of an exhaust gas sensor.