Engine Restart Device Adaptive Crankshaft Reverse Rotation Control
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Solution Overview
Problem
At high altitudes, the decrease in atmospheric pressure results in a reduction of override torque at the compression top dead center, causing the engine to fail to stop at the desired position during reverse rotation, leading to continuous reverse rotation and impaired engine restartability.
Innovation Solution
Incorporating an atmospheric pressure measuring unit and a three-phase brushless starter/generator, the controller adjusts the drive duty ratio based on atmospheric pressure measurements to control the reverse rotation speed and torque, ensuring accurate reverse rotation to a predetermined position and rapid engine restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is reversely rotated after automatic stop to prepare for restart, then the startability is improved, but at high altitudes the reverse rotation torque exceeds the reduced override torque causing continuous reverse rotation and failure to stop at the desired position
Solution Approach 1:
The patent applies dynamics by making the reverse rotation control adaptive to changing atmospheric pressure conditions. The controller dynamically adjusts the reverse rotation torque based on real-time atmospheric pressure detection, transitioning from a fixed torque approach to a variable torque control system that maintains optimal performance across different altitudes and environmental conditions.
Solution Approach 2:
The patent changes the torque parameter of the reverse rotation based on atmospheric pressure measurements. By detecting atmospheric pressure and correspondingly adjusting the reverse rotation torque, the system adapts to high altitude conditions where lower atmospheric pressure reduces the override torque, preventing continuous reverse rotation and ensuring accurate stopping at the desired crankshaft position.
2Device complexity
If a fixed reverse rotation torque is applied regardless of atmospheric pressure, then the control system is simple, but the engine cannot be stopped at the desired position under varying atmospheric pressure conditions
Solution Approach 1:
The patent implements feedback control by detecting atmospheric pressure and using this information to adjust the reverse rotation torque. The atmospheric pressure detection unit provides real-time environmental data to the controller, which then modulates the reverse rotation torque accordingly, creating a closed-loop control system that maintains accuracy without excessive complexity.
Solution Approach 2:
The system performs self-adjustment by automatically modifying the reverse rotation torque based on detected atmospheric pressure conditions. The controller autonomously determines the appropriate torque level without requiring manual intervention or complex external control systems, achieving adaptive performance through self-service control.
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 allows the engine to be accurately stopped at the desired position regardless of atmospheric pressure fluctuations, enhancing engine restartability and reducing processing load by using a duty ratio map to determine the appropriate drive duty ratio.
Implementation Method 1
an atmospheric pressure measuring unit 252 for measuring an atmospheric pressure
Implementation Method 2
the starter is a three-phase brushless starter/generator (171), and the controller (160) changes the drive duty ratio of the starter
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
To stop an engine at a position before a compression top dead center regardless of fluctuation of an atmospheric pressure when reversely rotating a crankshaft after stopping the engine to prepare for the next start. A controller (160) performs idle stop when the stop of the vehicle is detected based on the vehicle speed, and performs idle stop control to normally rotate the crankshaft after reversely rotating it when restarting the engine. The controller (160) controls the speed at which the crankshaft (12) is reversely rotated by a starter/generator (171) in accordance with the measurement result of the atmospheric pressure by an atmospheric pressure measuring unit (252). The atmospheric pressure can also be measured with reference to the detected value of an intake pressure sensor of the engine. The controller (160) changes a drive duty ratio of the starter based on the measurement result of the atmospheric pressure. The correspondence relationship between the atmospheric pressure and the drive duty ratio is stored in a map format (307), and the controller (160) refers to the map based on the measurement result of the atmospheric pressure to determine the drive duty ratio.