Engine Start-Up Controller Shift Position Limit Control
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Solution Overview
Problem
Conventional engine control systems face challenges in suppressing revving-up of engines during start-up while maintaining start-up performance, leading to potential torque shock and inefficient fuel usage, particularly in idle-stop modes where quick restarts are required.
Innovation Solution
A start-up controller that detects the shift position of the automatic transmission, adjusts the limit rotation rate based on the detected position, and performs limit control to prevent excessive engine rotation, incorporating feedback control to stabilize the engine at the target idle rotation rate, and adjusts torque output to match driver intention and engine conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the fuel injection rate and air intake rate are reduced to suppress engine revving-up after start-up, then the harmful effect of excessive rotation rate is reduced, but the start-up performance and torque output are impaired
Solution Approach 1:
The patent applies dynamics by making the fuel injection rate and air intake rate variable over time. Immediately after start-up, higher injection rates are used to ensure adequate torque, then the rates are dynamically reduced to a lower level to suppress revving-up. This time-varying control strategy allows the system to adapt to different operational phases, achieving both adequate start-up performance and suppression of excessive rotation.
Solution Approach 2:
The patent implements preliminary action by pre-setting different fuel injection rates and air intake rates for different time periods after start-up. The control strategy is prepared in advance, with higher rates scheduled for the immediate post-start-up period and lower rates scheduled for the subsequent period, ensuring smooth transition without performance loss.
2Speed
If the engine rotation rate is controlled to equal the criterial idling speed, then the idling control is achieved, but the actual rotation rate may instantaneously exceed the idling speed due to surge air tank pressure
Solution Approach 1:
The patent applies feedback control by continuously monitoring the actual engine rotation rate and comparing it with the target idling speed. When the actual rate exceeds the target, the control system adjusts the fuel injection rate and air intake rate to bring the rotation rate back to the desired level. This closed-loop control ensures stable idling operation despite disturbances from surge air tank pressure.
3Extent of automation
If the gear position is maintained during idle-stop control, then the auto-restart control is enabled, but torque shock and unintended acceleration occur due to torque converter amplification
Solution Approach 1:
The patent applies preliminary anti-action by detecting the gear position and predicting potential torque shock before it occurs. When the gear position indicates a high risk of torque shock (such as in drive range), the control system preemptively adjusts the fuel injection rate and air intake rate to limit engine rotation rate increase, thereby preventing torque shock and unintended acceleration before they can occur during auto-restart.
Data Source
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AI summary
A start-up controller of an engine includes a shift-position detector (32), a first setter (4a) and a limit controller (5). The shift-position detector (32) detects whether a position (RNG) of a select lever of an automatic transmission (26) is in a driving range. The first setter (4a) determines a limit rotation rate (NeLIM_H) based on the position (RNG) detected by the shift-position detector (32) at start-up of the engine (10) as a limit of the rotation rate of engine. The limit rotation rate (NeLIM_H) is determined lower when the position (RNG) is in the driving range compared to when the position (RNG) is not in the driving range. A 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.