Fuel Injection Controller Abnormality Compensation
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Solution Overview
Problem
Existing fuel injection controllers for internal combustion engines with common rail systems face deteriorated controllability of fuel pressure when abnormalities occur in the pressure-feeding systems, leading to decreased fuel pressure and impaired control stability, especially during transitional periods.
Innovation Solution
A fuel injection controller with a control device and an increasing device that adjusts the operation amount of the fuel pump based on abnormality information from other pressure-feeding systems, allowing for compulsory changes to maintain target fuel pressure even in abnormal conditions, and improves feedback control performance by using abnormal and normal period maps to manage pressure-feeding start angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is used to maintain fuel pressure, then fuel pressure controllability is improved under normal conditions, but response delay occurs immediately after abnormality is caused
Solution Approach 1:
The control device performs preliminary action by detecting abnormalities in pressure-feeding systems in advance and proactively increasing the operation amount of the fuel pump before fuel pressure deviation occurs. This prevents the response delay inherent in feedback control by acting preemptively based on abnormality detection, thereby maintaining fuel pressure controllability without waiting for pressure deviation to be detected.
2Speed
If open control is used to improve following performance during transitional period, then fuel pressure follows target pressure better, but controllability deteriorates when abnormality is caused in pressure-feeding system
Solution Approach 1:
The control device dynamically adjusts the operation amount of the fuel pump based on the operational state of each pressure-feeding system. When an abnormality is detected in one system, the control device automatically increases the operation amount of the remaining normal systems to compensate for the lost capacity. This dynamic adaptation maintains both the following performance during transitional periods and the overall controllability under abnormal conditions.
3Reliability
If feedback control compensates for pressure deviation, then fuel pressure is maintained, but the control stability deteriorates during transitional period after abnormality
Solution Approach 1:
By detecting abnormalities beforehand and preemptively adjusting the fuel pump operation amount, the control device prevents large pressure deviations from occurring in the first place. This eliminates the need for aggressive feedback control corrections that would cause instability during transitional periods, thereby maintaining both fuel pressure and control stability simultaneously.
Data Source
AI summary
A fuel injection controller calculates a fuel pressure-feeding start angle of a fuel pump as a valve opening start angle of a metering valve, which regulates a discharge amount, by adding a base angle and a feedback correction value. The base angle is calculated in accordance with a command injection amount and target fuel pressure based on a basic map. The feedback correction value is calculated based on differential pressure between sensed fuel pressure and the target fuel pressure. If an abnormality is caused in either one of two metering valves, the base angle is calculated based on an abnormal period map instead of the basic map. Thus, controllability of the fuel pressure is maintained high even when the abnormality is caused in a part of multiple pressure-feeding systems including multiple plungers of the fuel pump.