In-Cylinder Injection Controller Fuel Pressure Correction
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Solution Overview
Problem
In-cylinder injection engines face challenges in accurately correcting fuel pressure fluctuations due to high-pressure pump discharge during the injection waiting period, leading to inaccurate fuel pressure correction and injection amount control.
Innovation Solution
A controller system that includes a fuel pressure sensor, a fuel pressure controlling device, a fuel pressure correcting device, and an injection setting device, which estimates the fuel pressure at the injection start time and sets a fuel pressure correction coefficient based on this estimation to accurately correct the injection period and amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fuel pressure correction is performed using the fuel pressure sensed at the injection setting time, then the control process is simple, but the fuel pressure correction accuracy deteriorates when fuel pressure fluctuates during the injection waiting period
Solution Approach 1:
The patent applies preliminary action by estimating the fuel pressure at the injection start time before the actual injection occurs. The ECU calculates the fuel pressure increase that occurs during the injection waiting period and adds it to the sensed fuel pressure at the injection setting time, thereby obtaining an estimated fuel pressure at the injection start time. This estimated value is then used for accurate fuel pressure correction of the injection period, resolving the accuracy problem while maintaining relatively simple control logic.
2Productivity
If the high-pressure pump discharges fuel during the injection waiting period, then the fuel pressure increases, but the actual fuel pressure at injection start time becomes higher than expected, causing injection amount error
Solution Approach 1:
The patent applies feedback by using the fuel pressure sensor to sense the actual fuel pressure at the injection setting time, then feeding this information back to the ECU. The ECU calculates the fuel pressure increase during the injection waiting period based on this feedback and uses it to correct the injection period. This feedback mechanism allows the system to compensate for pressure changes caused by high-pressure pump discharge, maintaining accurate injection amounts despite productivity-related pressure fluctuations.
3Loss of time
If the injection waiting period is extended, then the injection setting can be done earlier, but the fuel pressure fluctuation due to high-pressure pump discharge increases, worsening correction accuracy
Solution Approach 1:
The patent applies preliminary action by performing the fuel pressure estimation and correction calculation in advance during the injection waiting period. The ECU calculates the expected fuel pressure increase based on the duration of the injection waiting period and the high-pressure pump discharge characteristics, and pre-adjusts the injection period accordingly. This allows the system to maintain accurate injection control even when the injection waiting period is extended for timing purposes.
Data Source
AI summary
If a high-pressure pump discharges fuel in an injection waiting period from injection setting to injection start, fuel pressure to occur at injection start time is estimated and a fuel pressure correction coefficient is calculated based on the estimated fuel pressure. If there is no fuel discharge in the injection waiting period, the fuel pressure sensed at the injection setting is regarded as the fuel pressure of the injection start time, and the fuel pressure correction coefficient is calculated based on the sensed fuel pressure. A final injection period is calculated by correcting a basic injection period with the fuel pressure correction coefficient. Thus, fuel pressure correction of the injection period is performed accurately even if actual fuel pressure fluctuates due to the fuel discharge from the high-pressure pump during the injection waiting period.