Fuel Injection Control Device Voltage Rise Prevention
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Solution Overview
Problem
Existing fuel injection systems face challenges in managing excessive voltage rise in the booster circuit, which can lead to failure of the surplus power consumption circuit due to excessive current flow, especially when the fuel pump is continuously driven without the injector being active.
Innovation Solution
A control device that includes a compression command generation device, a fuel-pump drive circuit, an injector drive circuit with a power storage element, a charging circuit, and a surplus power consumption circuit, which counts the driving count of the fuel pump during periods of injector inactivity and adjusts energization control to prevent excessive voltage rise by stopping or intermittently operating the fuel pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the fuel pump is continuously driven to maintain fuel pressure, then the fuel pressure is maintained, but excessive voltage rises in the power storage element causing potential failure of the surplus power consumption circuit
Solution Approach 1:
The control device implements periodic action by alternating between driving and stopping the fuel pump based on a counter value. When the counter reaches a predetermined threshold during periods when the injector is not driven, the fuel pump is stopped temporarily, then restarted after a predetermined period elapses. This periodic operation prevents continuous voltage accumulation in the power storage element while maintaining fuel pressure stability.
Solution Approach 2:
The control device uses feedback control by monitoring the counter value that tracks fuel pump operation cycles. The counter increments each time the fuel pump is driven during periods when the injector is inactive, and this feedback signal triggers the control device to stop the fuel pump when the threshold is reached, creating a closed-loop control system that prevents excessive voltage rise.
2Reliability
If the surplus power consumption circuit operates frequently to consume excess power, then excessive voltage rise is prevented, but the circuit experiences excessive current flow leading to potential failure
Solution Approach 1:
The control device performs preliminary action by stopping the fuel pump before excessive voltage can accumulate to dangerous levels. By monitoring the counter value and stopping the fuel pump when the predetermined threshold is reached, the system proactively prevents the condition that would require the surplus power consumption circuit to operate, thereby avoiding excessive current flow through that circuit.
3Reliability
If the fuel pump is stopped intermittently to prevent voltage rise, then the surplus power consumption circuit is protected, but fuel pressure may fluctuate
Solution Approach 1:
The control device applies dynamics by adaptively adjusting fuel pump operation based on real-time conditions. The system dynamically switches between driving and stopping the fuel pump according to the counter value and predetermined thresholds, creating a flexible control strategy that maintains fuel pressure stability while protecting the surplus power consumption circuit from excessive voltage and current.
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 effectively prevents excessive voltage rise in the power storage element, reduces the frequency of surplus power consumption circuit operation, and protects both the surplus power consumption circuit and injector drive circuit from overheating and failure.
Implementation Method 1
an injector drive circuit that includes a power storage element for storing electric power to be used in driving of the injector
Implementation Method 2
a charging circuit that leads current generated during energization stop of the electromagnetic valve to the power storage element
Implementation Method 3
a surplus power consumption circuit that consumes surplus electric power of the power storage element
Data Source
AI summary
A control device for a fuel injection system includes a CPU which generates a drive signal for instructing execution of compression by a fuel pump; a fuel pump drive circuit which controls application of electric power to a solenoid of the fuel pump based on the drive signal; a boost circuit provided with a capacitor for storing electric power to be used for driving an injector; a charging circuit which leads a current generated when the application of electric power to the solenoid is stopped to the capacitor; and an excess electric power consumption circuit which consumes excess electric power of the capacitor. While fuel injection from the injector is stopped, the CPU counts the number of times the fuel pump is driven and turns off the drive signal so as to stop driving the fuel pump as soon as the drive count has exceeded a predetermined count value.