Startup Controller for In-Cylinder Injection Engine
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Solution Overview
Problem
In-cylinder injection internal combustion engines face challenges with prolonged startup times and increased emissions due to insufficient fuel pressure at startup, which existing solutions attempt to address by stopping injection until fuel pressure reaches a high range, leading to prolonged startup times and increased unburned hydrocarbon emissions.
Innovation Solution
A startup controller that includes an injection setting device, an injection controlling device, a fuel pressure sensing device, and a startup controlling device, which estimates fuel pressure at the injection start and determines whether to perform or prohibit injection based on the sensed pressure, allowing injection to commence even if the actual fuel pressure has not reached the required range, ensuring proper atomization and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If injection is stopped until fuel pressure reaches high range, then fuel atomization is improved, but startup time is prolonged and emissions increase
Solution Approach 1:
The high-pressure pump is activated in advance during engine cranking to build fuel pressure before injection is needed. The ECU controls the pump to operate during the cranking period, so that when injection starts, sufficient fuel pressure is already available, eliminating the need to delay injection for pressure buildup.
Solution Approach 2:
The system uses a fuel pressure sensor to continuously monitor fuel pressure and feeds this information back to the ECU. The ECU uses this feedback to determine the optimal timing for starting injection, allowing injection to begin as soon as sufficient pressure is available rather than using a fixed delay period.
2Loss of time
If high-pressure pump size is increased to shorten fuel pressure increasing time, then startup time is shortened, but mountability deteriorates and fuel pressure controllability worsens
Solution Approach 1:
The system dynamically controls the high-pressure pump operation based on real-time engine conditions. The ECU adjusts pump activation timing and duration according to crankshaft position, engine speed, and fuel pressure feedback, optimizing pressure buildup without requiring a larger pump.
Solution Approach 2:
The system changes operational parameters (pump activation timing, injection timing, injection duration) to optimize startup performance. By precisely controlling when the pump operates and when injection begins, the system achieves rapid pressure buildup using the existing pump size.
3Loss of time
If fuel pipe volume is decreased to shorten fuel pressure increasing time, then startup time is shortened, but fuel pressure stability deteriorates
Solution Approach 1:
The high-pressure pump operates continuously during the cranking period to maintain steady pressure buildup. This continuous operation, rather than intermittent pumping, ensures stable fuel pressure is achieved rapidly and maintained throughout the startup process.
Data Source
AI summary
A startup controller calculates a fuel pressure difference across a discharge stroke of a high-pressure pump at an end of an initial discharge after cranking is started. At the injection setting, the startup controller estimates a fuel pressure increment from an injection setting to an injection start based on the fuel pressure difference. The startup controller adds the fuel pressure increment to a fuel pressure sensed at the injection setting to estimate a fuel pressure at the injection start. The startup controller determines whether to perform or to prohibit the injection based on whether the estimated fuel pressure at the injection start is equal to or higher than an injection permission fuel pressure.