Fuel Injector Bypass and Boost Voltage Control for Engine Starting
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Solution Overview
Problem
Large fuel injectors in vehicles with large engines face difficulty in starting due to high spring forces and insufficient battery voltage, especially under hot soaked conditions, leading to increased resistance and voltage drops that prevent the fuel injectors from opening.
Innovation Solution
A system comprising a powertrain control module (PCM) that generates a bypass enable signal to provide system voltage directly to the fuel injectors and a boost voltage circuit to increase the voltage to a boosted level, overcoming the spring force and ensuring proper injector operation during engine starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large fuel injector with a large spring is used to handle large engine fuel requirements, then the fuel delivery capacity is improved, but the spring force increases making it difficult to open the injector with available battery voltage
Solution Approach 1:
A bypass voltage circuit is introduced as an intermediary component that provides an alternative voltage path to the fuel injector. This bypass circuit includes a bypass relay that can connect the injector directly to the battery through a bypass relay coil, eliminating the voltage drop across the injector driver circuit and providing sufficient voltage to overcome the large spring force in large fuel injectors.
2Power
If the vehicle battery provides high voltage to the starter motor during engine starting, then the starter motor has sufficient power to crank the engine, but the voltage applied to the fuel injector solenoid becomes insufficient to open the injector
Solution Approach 1:
The voltage supply path to the fuel injector is segmented into two independent paths: a normal path through the injector driver circuit and a bypass path through the bypass relay. During engine starting when battery voltage is needed for the starter motor, the bypass path can be activated to provide sufficient voltage directly to the injector, separating the power delivery requirements of the starter and injector.
Solution Approach 2:
The system dynamically switches between normal operation mode and bypass mode based on engine starting conditions. The bypass relay coil is energized during cranking to activate the bypass path, and deactivates during normal operation, allowing the system to adapt its voltage supply configuration to meet changing operational requirements.
3Reliability
If the fuel injector resistance increases under hot soaked conditions, then the injector becomes more difficult to open, but the available battery voltage remains the same
Solution Approach 1:
The bypass voltage circuit is prepared in advance and can be rapidly activated when hot soaked conditions are detected or during engine starting. By having the bypass circuit pre-configured and ready, the system can immediately provide sufficient voltage to overcome increased injector resistance without waiting for voltage drops to occur.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system ensures reliable engine starting by providing sufficient voltage to the fuel injectors, even under voltage drops, by using a bypass and boost voltage circuit to maintain stable and clean power supply during the starting process.
Implementation Method 1
A boost voltage circuit is electrically coupled to the fuel injector and configured to increase a system voltage of a vehicle to a boosted voltage during the boost enable signal
Implementation Method 2
A bypass voltage circuit is electrically coupled to the fuel injector and is configured to provide a system voltage of a vehicle to the fuel injector during a bypass enable signal
Implementation Method 3
By supplying a sufficiently high voltage to the mechanism or device (e.g., solenoid) that opens the fuel injector, the spring force is overcome
Data Source
AI summary
An apparatus for controlling power for a fuel injector includes a fuel injector configured to inject fuel to a cylinder of an engine and a powertrain control module generating a bypass enable signal or a boost enable based on the engine cranking signal. A bypass voltage circuit is electrically coupled to the fuel injector and is configured to provide a system voltage of a vehicle to the fuel injector during a bypass enable signal. A boost voltage circuit is electrically coupled to the fuel injector and configured to increase a system voltage of a vehicle to a boosted voltage during the boost enable signal, wherein the boosted voltage is higher than the system voltage.