Electromagnetic Valve Driver Flyback Energy Management
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Solution Overview
Problem
Conventional fuel injection control devices suffer from open failures in the discharge switch, leading to abnormal voltage rises in the capacitor, causing multi-component failures and hindering vehicle operation due to the inability to collect flyback energy effectively.
Innovation Solution
An electro-magnetic valve driver with a downstream switch and a first upstream switch, along with a flowback section and delay section, is used to manage the electric current flow and delay the switch-off timing to reduce flyback energy collection, preventing capacitor voltage rise and ensuring continued valve control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge switch suffers from open failure, then the valve opening operation can still be performed using constant current circuit, but the charge voltage of the capacitor will rise abnormally due to flyback energy collection
Solution Approach 1:
The control device detects the open failure of the discharge switch in advance and takes preventive action by stopping the operation of the energy collection circuit before the capacitor voltage can rise to harmful levels. This predictive control prevents the voltage rise problem from occurring in the first place.
Solution Approach 2:
The control device continuously monitors the state of the discharge switch and the capacitor voltage, and based on this feedback information, dynamically adjusts the operation of the energy collection circuit. When an open failure is detected, the feedback mechanism triggers the stoppage of energy collection to prevent voltage rise.
2Object-affected harmful factors
If the drive of the injector is stopped to prevent multi-component failure, then the capacitor voltage rise is prevented, but the vehicle's ability to travel is hindered
Solution Approach 1:
The system dynamically adjusts its operation mode based on the detected failure state. When the discharge switch fails open, the system transitions from normal operation (where energy collection is active) to a degraded operation mode (where energy collection is stopped but injection continues). This dynamic adaptation allows the vehicle to remain operational despite the failure.
Solution Approach 2:
The control device prepares for potential discharge switch failures by having a pre-planned response strategy. Upon detecting the open failure, the system immediately implements the protective measure of stopping energy collection, cushioning against the potential damage before it can occur, while maintaining injection functionality.
3Speed
If the charge voltage is boosted to target voltage for quick valve opening, then the responsiveness is improved, but the risk of abnormal voltage rise increases when discharge switch fails
Solution Approach 1:
The system uses feedback control to monitor the discharge switch status and capacitor voltage levels. When the discharge switch is detected to have failed open, the feedback mechanism immediately adjusts the operation of the energy collection circuit to stop charging the capacitor, thereby preventing voltage rise that would compromise circuit element safety while maintaining the boosted voltage capability for normal operation.
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 solution allows for continued drive control of the electro-magnetic valve without damaging other components, reducing the need for additional circuits and ensuring vehicle operation is not hindered by preventing capacitor voltage from exceeding safe limits.
Implementation Method 1
a capacitor C0 storing an electric energy to be discharged to the coil 2a
Implementation Method 2
the flyback energy (i.e., a counter-electromotive energy) that is generated at the end timing of the electricity supply time
Data Source
AI summary
An electromagnetic valve driver, in normal operation, supplies peak current from a capacitor to a coil of an injector by turning ON a transistor on a downstream side of the coil and a discharge transistor that discharges electricity from the capacitor to the coil. Thereafter, the driver supplies constant current to the coil by an ON-OFF control of a transistor disposed between a battery and an upstream side of the coil until an end of the electricity supply period. When an open failure of the discharge transistor is detected, the driver controls the current to prevent a voltage rise of the capacitor to reduce flyback energy collected from a downstream side of the coil by the capacitor based on a transistor OFF timing delay scheme, in which an OFF timing of a transistor is delayed by a preset delay time from a normal OFF timing thereof.