Idle Speed Control Valve Latch Circuit for Engine Start Stability
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Solution Overview
Problem
Existing engine start control devices face issues with poor starts and unstable engine behavior due to voltage fluctuations causing the control unit to reset, leading to incorrect adjustment of the idle speed control valve's opening degree.
Innovation Solution
An engine start control device with a latch circuit that maintains current supply to the starter motor and includes a reset determining mechanism to prevent reinitialization of the idle speed control valve's opening degree, ensuring it remains at the target setting even after voltage resets, and utilizes sensors to verify the actual opening degree.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control unit drives the stepping motor to adjust the ISCV opening degree when the ignition switch is turned on, then the intake amount suitable for engine start is ensured, but the supply voltage decreases due to starter motor current, causing control unit resetting and incorrect ISCV positioning
Solution Approach 1:
The control unit performs preliminary adjustment of the ISCV opening degree before starting the starter motor. By pre-positioning the ISCV to the target opening degree while the battery voltage is still stable, the system ensures correct intake amount for engine start without the interference of voltage drop that occurs when the starter motor is activated.
2Ease of operation
If the control unit tries to move the ISCV to target opening degree after resetting, then the control unit reactivates, but the ISCV position is greatly deviated from target, causing poor start and unstable engine behavior
Solution Approach 1:
The ISCV is pre-adjusted to the target opening degree before the control unit resetting occurs. This preliminary positioning ensures that when the control unit reactivates after voltage recovery, the ISCV is already at the correct position, preventing the deviation problem that would occur if the control unit tried to reposition it after resetting.
3Reliability
If the control unit does not operate the ISCV when resetting due to voltage decrease, then CPU resetting problems are avoided, but the ISCV opening degree is not properly maintained, causing poor start and unstable engine behavior
Solution Approach 1:
The ISCV opening degree is adjusted to the target position before the voltage decrease and control unit resetting occurs. This preliminary action ensures that the ISCV maintains its correct opening degree even when the control unit resets, as the positioning is completed while the control unit is still stable and operational.
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 prevents poor starts and unstable engine behavior by maintaining the correct opening degree of the idle speed control valve, reducing battery consumption, and minimizing the need for unnecessary initialization, thus ensuring a stable engine operation.
Implementation Method 1
an idle speed control valve (ISCV) for controlling an idle speed is provided in a bypass channel bypassing a throttle valve of the engine. The ISCV is structured to be capable of adjusting its opening degree by a stepping motor
Implementation Method 2
a starter motor capable of driving a crankshaft of the engine
Data Source
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AI summary
An engine start control device (10) includes: a control valve (ISCV,106) which adjusts a gas flow rate of a gas channel (43) provided so as to bypass a throttle valve (42) of an engine (4); a starter motor (102) capable of driving a crankshaft (41) of the engine (4); a control unit (104) which controls an opening degree of the control valve (ISCV,106) and a current supply to the starter motor (102); and a latch circuit (105) which holds a command for current control from the control unit (104) to the starter motor (102), wherein the control unit (104) performs the control so as to cause the current supply to the starter motor (102) to start after the opening degree of the control valve (ISCV,106) reaches a target opening degree for an engine start time, and even when the control unit is reset, the latch circuit (105) continues the current supply to the starter motor (102) according to the command for current control that the latch circuit keeps holding.