Engine Start-Up Controller With Dynamic Rotation Rate Limit
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Solution Overview
Problem
Conventional engine start-up systems face challenges in suppressing revving-up of the engine after start-up while maintaining start-up performance, leading to potential torque deficiencies and delayed vehicle acceleration in idle-stop modes.
Innovation Solution
An engine start-up controller that detects driver intention and adjusts the limit rotation rate of the engine, incorporating feedback control to stabilize the engine at a target idle rotation rate, thereby preventing sudden increases in engine speed and ensuring sufficient torque for quick start-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the fuel injection rate and air intake rate are decreased to suppress revving-up, then the exhaust performance and fuel efficiency are improved, but the torque generated at the engine decreases, impairing the start-up performance
Solution Approach 1:
The patent applies dynamics by making the rotation rate limit value variable based on driver start intention. The ECU sets different limit values (e.g., 3000 rpm for strong start intention, 2000 rpm for weak start intention) depending on accelerator pedal depression and brake release status. This dynamic adjustment allows the system to suppress revving-up when unnecessary while permitting higher rotation rates when quick start is needed, thus resolving the contradiction between suppressing harmful revving-up and maintaining sufficient torque for start-up performance.
2Object-generated harmful factors
If the fuel injection rate and air intake rate are decreased to suppress revving-up, then the exhaust performance is improved, but the amount of time for the engine to reach stable idling state increases, deferring quick start of the vehicle
Solution Approach 1:
The system dynamically adjusts the rotation rate limit based on driver intention detected through accelerator and brake signals. When quick start is needed (accelerator depressed, brake released), the limit is set higher, allowing the engine to reach stable idling faster. When start intention is weak, the limit is lower to suppress revving-up. This time-dependent dynamic control resolves the contradiction between suppressing revving-up and reducing time to stable idling.
3Object-generated harmful factors
If a fixed limit rotation rate is set to suppress revving-up, then the exhaust performance is improved, but the requested actual rotation rate and torque may not be guaranteed under varying start-up conditions
Solution Approach 1:
The patent implements dynamic adaptation by continuously monitoring driver inputs (accelerator pedal position, brake status) and adjusting the rotation rate limit accordingly. The system adapts to varying start-up conditions by setting appropriate limits: higher limits for strong start intention, lower limits for weak start intention. This dynamic adaptability resolves the contradiction between suppressing revving-up and guaranteeing requested rotation rate and torque under different conditions.
Solution Approach 2:
The system uses feedback from sensors detecting accelerator pedal depression and brake release status to continuously adjust the rotation rate limit. This feedback mechanism allows the ECU to respond to changing driver intentions and vehicle conditions in real-time, ensuring the limit rotation rate is always appropriate for current start-up conditions while still suppressing harmful revving-up when unnecessary.
Data Source
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AI summary
A start-up controller of an engine includes an intention detector (31, 33), a first setter (4a) and a limit controller (5). The intention detector (31, 33) detects an intensity of a start intention of a driver. The first setter (4a) determines a limit rotation rate (NELIM_H) based on the start intention detected by the intention detector (31, 33), as a limit of the rotation rate of the engine, wherein the limit rotation rate (NeLIM_H) decreases as the start intention weakens. The limit controller (5) performs limit control for controlling the actual rotation rate (Ne) of the engine so as not to exceed the limit rotation rate (NeLIM_H) determined by the first setter (4a). Such a configuration prevents revving-up of the engine at start-up while improving the start-up performance.