Injector Driver Circuit Current Detection During Regeneration
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Solution Overview
Problem
Conventional internal combustion engine controllers for cylinder direct injection type injectors face challenges in precise current control during the reduction period, particularly when regenerating electric energy to the voltage booster circuit, as they cannot detect the injector current with downstream side current detector resistors during this phase, leading to inefficiencies and heat generation issues.
Innovation Solution
The implementation of a driver circuit with a voltage booster circuit, switching elements, current detection resistors, and a current regeneration diode allows for precise current control during the reduction period by detecting currents through different resistors and regenerating energy back to the voltage booster circuit, without altering the conventional injector driver circuit structure and reducing the number of components needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the injector current is reduced in a short time by regenerating energy to the voltage booster circuit, then the valve can be closed immediately after injection, but the downstream side current detector resistor cannot detect the injector current during this period
Solution Approach 1:
The patent introduces an intermediary current detection path through the voltage booster circuit. During the current reduction period, the current that would otherwise be undetectable flows through the voltage booster circuit's internal resistance, serving as an intermediary measurement path. This allows the control unit to indirectly detect the injector current magnitude during the regeneration phase without requiring the downstream side current detector resistor to remain functional when the FET is fully turned off.
2Loss of energy
If the first downstream side driver FET is perfectly turned off to enable energy regeneration, then heat generation is suppressed, but the injector current cannot be detected with the downstream side current detector resistor
Solution Approach 1:
The voltage booster circuit serves as an intermediary measurement path. When the first downstream side driver FET is perfectly turned off and the current regeneration diode conducts, the injector current flows through the voltage booster circuit's internal resistance. This intermediary path allows the control unit to detect the current magnitude through voltage measurement across the booster circuit's internal resistance, eliminating the need for the downstream side current detector resistor to remain functional during this phase.
3Measurement precision
If a downstream side current detector resistor is used for precise current control during the exciting period, then current control is accurate, but the resistor cannot detect current during the reduction period when the FET is turned off
Solution Approach 1:
The voltage booster circuit is given multiple functions: it continues to serve as the power supply for the injector while simultaneously acting as a current sensing mechanism during the reduction period. The control unit measures the voltage across the booster circuit's internal resistance to determine the current magnitude, allowing the same circuit to perform both power delivery and measurement functions across different operational phases.
Solution Approach 2:
The voltage booster circuit acts as an intermediary sensing path. During the reduction period when the FET is turned off, the current flows through the booster circuit's internal resistance, which serves as an intermediary measurement path. The control unit indirectly measures the current through this intermediary path, extending the detection coverage to include the reduction period that would otherwise be undetectable.
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
This solution enables precise current control during the entire current exciting period, including the reduction phase, while minimizing heat generation and maintaining the existing circuit structure, thus improving the reliability and efficiency of the engine controller.
Implementation Method 1
a voltage booster circuit for boosting a battery voltage to a higher voltage and making the voltage boosted by the voltage booster circuit increase an exciting current to the injector in a short time
Implementation Method 2
a method of regenerating the injector current to a voltage booster capacitor of the voltage booster circuit for accumulating a boosted voltage
Implementation Method 3
a method of converting energy into thermal energy by driver elements of a driver circuit for driving the injector current by utilizing the Zener diode effects
Data Source
AI summary
An internal combustion engine controller has: a voltage booster circuit for boosting a battery power source; a booster side driver element for flowing a current through the injectors by using the boosted voltage; a battery side driver element disposed in parallel with the booster side driver element to flow a current through the injectors by using the battery power source; a first downstream side driver element provided by controlling currents flowing through the injectors; current regeneration diodes for flowing currents from the downstream side to the upstream side of the injectors; a booster side current detector resistor for detecting currents flowing via the current regeneration diodes; and an injector control circuit for controlling and driving the booster side driver element, battery side driver element and first downstream side driver element.