Fuel Injection Control Device for Transient Engine Operation
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Solution Overview
Problem
Existing fuel injection control systems for engines with in-cylinder injectors face challenges in maintaining accurate fuel pressure measurements, particularly in transient operational states, leading to deteriorated combustion conditions in both transient and high engine speed ranges.
Innovation Solution
A fuel injection control device that uses instantaneous fuel pressure values detected at specific timings and calculates average fuel pressures over shorter periods than the fuel pump's operation cycle, improving response and accuracy of injection pulse widths to match actual fuel pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an average value of fuel pressure is used for calculation of injection pulse width, then stability is improved, but response to fuel pressure changes deteriorates especially in transient operation
Solution Approach 1:
The patent applies dynamics by making the calculation period adaptive rather than fixed. The control device dynamically adjusts the calculation period based on engine operating conditions: using a first (longer) calculation period for stable operation to ensure combustion stability, and a second (shorter) calculation period for transient operation to improve response speed. This dynamic adjustment resolves the contradiction between stability and response speed.
2Speed
If instantaneous fuel pressure value is used for calculation, then response to fuel pressure changes is improved, but stability deteriorates especially in high engine speed range
Solution Approach 1:
The control device dynamically selects between instantaneous value and averaged value based on operating conditions. In transient operation, it uses instantaneous fuel pressure values with a shorter calculation period to capture rapid changes, improving response speed. In stable high-speed operation, it uses averaged values with a longer calculation period to smooth fluctuations, maintaining combustion stability.
3Measurement precision
If a long period is used for calculation of average fuel pressure, then measurement accuracy is improved, but response to fuel pressure changes deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of the calculation period based on engine operating state. During transient operation when rapid fuel pressure changes occur, it uses a shorter calculation period to reduce time delay and improve response. During stable operation when fuel pressure is relatively constant, it uses a longer calculation period to improve measurement accuracy by averaging out fluctuations.
4Loss of time
If a short period is used for calculation of average fuel pressure, then response to fuel pressure changes is improved, but measurement accuracy deteriorates
Solution Approach 1:
The control device dynamically adjusts the calculation period based on operating conditions. In transient operation, it uses a shorter calculation period to capture rapid fuel pressure changes, accepting some reduction in measurement accuracy for the benefit of timely response. In stable operation, it extends the calculation period to improve measurement accuracy by averaging, when rapid changes are less critical.
Data Source
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AI summary
A fuel injection control device is provided for enabling an improvement of combustion in a transient operation of the engine with improvement of combustion in normal operation at a high engine speed. An average fuel pressure calculating period for detecting fuel pressure for calculating an average fuel pressure is set to a period shorter than a cycle of a high-pressure pump. An average value of fuel pressure detected in the average fuel pressure calculating period is calculated as average fuel pressure. Calculated average fuel pressure is used in computing an injection pulse width of an in-cylinder injector relating to each of four cylinders.