Engine Start Control Atmospheric Pressure Detection
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Solution Overview
Problem
Existing engine start control systems without a battery cannot accurately detect atmospheric pressure during manual cranking using a recoil starter, as the ECM is not activated until the crankshaft rotates, making it difficult to determine atmospheric pressure from intake pipe pressure signals.
Innovation Solution
An engine start control system that includes a manual starter, generator, electronic fuel injector, pressure detection section, air regulator, and engine control device with a maximum value detection section, idling control section, and correction section to accurately estimate atmospheric pressure by detecting the maximum pressure in the intake pipe and adjusting for throttle aperture variations during manual cranking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ECM is activated only after the crankshaft rotates (without battery), then the system can operate without a battery, but the atmospheric pressure cannot be detected when the crankshaft is still
Solution Approach 1:
The patent performs preliminary action by detecting the maximum intake pipe pressure during manual cranking (before the engine starts) and using this value as the atmospheric pressure. This allows the ECM to obtain atmospheric pressure information even though it is activated only after the crankshaft rotates, resolving the contradiction between batteryless operation and pressure detection capability.
2Measurement precision
If the maximum value of pressure in the intake pipe during manual cranking is used as atmospheric pressure, then the system can determine atmospheric pressure without battery, but the accuracy is affected by throttle aperture variations
Solution Approach 1:
The patent applies feedback by detecting the actual throttle aperture during manual cranking and using this information to correct the atmospheric pressure calculation. The ECM adjusts the atmospheric pressure value based on the throttle aperture state, compensating for the effect of throttle opening on intake pipe pressure and thereby improving measurement reliability.
Solution Approach 2:
The patent changes the parameter used for atmospheric pressure determination from a fixed value to a dynamic calculation that considers throttle aperture. By introducing throttle aperture as a variable parameter, the system adapts the atmospheric pressure value to actual operating conditions, improving both accuracy and reliability.
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 provides a more accurate estimation of atmospheric pressure by correlating the air regulator's control volume with the pressure correction, ensuring precise fuel injection control even without a battery, improving engine starting efficiency and reducing costs.
Implementation Method 1
a pressure detection section which detects pressure in an intake pipe on the downstream side of a throttle valve of the engine
Implementation Method 2
a generator which operates in association with rotation of the crankshaft; an engine control device which operates using electric power generated by the generator
Data Source
AI summary
In the process of starting by a recoil starter, a maximum value detection section of an ECM detects a maximum value of pressure (basic atmospheric pressure) in an intake pipe detected by a pressure sensor, within a predetermined range of crank angle after activation of the ECM. An idling control unit gives feedback control on an ISC valve based on engine speed detected by an engine speed sensor, to thereby keep idling engine speed at a specified value. A correction unit corrects a basic atmospheric pressure detected by the maximum value detection section based on the duty ratio of the ISC valve in idling, and uses the result as the atmospheric pressure. A storage unit 9d stores a map in which the duty ratio of the ISC valve in idling is correlated with the amount of correction to be made on the basic atmospheric pressure.