Fuel Injection Control System Managing Vapor Generation
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Solution Overview
Problem
In fuel injection control systems for internal combustion engines with low and high pressure fuel pumps, maintaining low feed pressure while preventing vapor generation that could lead to misfires and air-fuel ratio deviations is challenging.
Innovation Solution
A fuel injection control system that uses proportional-integral control to adjust the duty cycle of the high pressure fuel pump based on the integral term, allowing for the lowering of feed pressure while monitoring the tendency of the integral term to prevent excessive vapor generation, without requiring additional sensors between the low and high pressure pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the feed pressure of the low pressure fuel pump is reduced to minimize energy consumption, then energy consumption is reduced, but vapor generation in the high pressure fuel pump increases
Solution Approach 1:
The system monitors the integral term from proportional-integral control of the high pressure fuel pump and uses this feedback to dynamically adjust the feed pressure. When the integral term increases indicating vapor generation, the feed pressure is automatically increased to prevent misfire, resolving the contradiction between low energy consumption and vapor prevention
Solution Approach 2:
The feed pressure is made dynamic rather than fixed, allowing it to be adjusted in real-time based on engine operating conditions and vapor generation risk. The control unit dynamically modifies the feed pressure within a range from low to high, optimizing both energy consumption and vapor prevention for different operating scenarios
2Reliability
If the feed pressure is increased to prevent vapor generation, then vapor generation is suppressed, but energy consumption of the low pressure fuel pump increases
Solution Approach 1:
The system changes the feed pressure parameter dynamically based on the integral term from proportional-integral control. By adjusting this parameter according to actual vapor generation risk rather than maintaining a constantly high value, the system ensures reliability while minimizing unnecessary energy consumption during normal operating conditions
3Measurement precision
If additional sensors are added to monitor fuel pressure between the low and high pressure pumps to detect vapor generation, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The system uses existing control components (the proportional-integral control unit and its integral term) to detect vapor generation conditions. Instead of adding dedicated sensors, the system leverages the self-generated control data to monitor fuel pressure conditions and detect vapor risk, maintaining measurement precision while avoiding increased device complexity
Solution Approach 2:
The proportional-integral control unit serves multiple functions: it controls the high pressure fuel pump while simultaneously providing vapor generation detection through its integral term. This multi-functionality eliminates the need for separate detection sensors, resolving the contradiction between detection accuracy and system complexity
Data Source
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AI summary
An object of the invention is to provide a technology that enables to make the feed pressure as low as possible without inviting a misfire or a deviation of the air-fuel ratio, in a fuel injection control system for an internal combustion engine equipped with a low pressure fuel pump and a high pressure fuel pump. According to the invention, to achieve the object, in a fuel injection control system for an internal combustion engine in which fuel discharged from a low pressure fuel pump is supplied to a fuel injection valve with its pressure boosted by a high pressure fuel pump, while a lowering process of lowering feed pressure or the discharge pressure of a the low pressure fuel pump, the lowering process is suspended and restarted with reference to the tendency of change in an integral term used in a proportional-integral control of the duty cycle of the high pressure fuel pump.