Auto-Stop Engine Rollback Control via Transmission Load Detection
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Solution Overview
Problem
Internal combustion engines face challenges in controlling engine speed during auto-stop/start events, leading to engine flare and vehicle rollback due to unaccounted transmission loads, which can cause stalls, vibrations, and other conditions.
Innovation Solution
A control system comprising a transmission load module, a target engine speed module, and an actuator control module that determines the load on the engine through the transmission and adjusts engine actuators to minimize engine flare and prevent rollback by selectively disabling auto-stop events and applying brakes during auto-start events based on predetermined load thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the ECM shuts down the engine to increase fuel efficiency, then fuel consumption is reduced, but engine speed control becomes difficult during startup events causing engine flare and vehicle rollback
Solution Approach 1:
The system determines the transmission load before the engine startup event occurs and uses this pre-determined load information to calculate the appropriate target engine speed. This preliminary assessment of transmission load allows the control system to prepare the correct speed target in advance, preventing engine flare and vehicle rollback during the startup transition.
Solution Approach 2:
The system continuously monitors transmission load and uses this feedback to dynamically adjust the target engine speed during startup events. By incorporating real-time transmission load information into the control loop, the system can adapt the engine speed target to current operating conditions, ensuring stable engine operation and preventing rollback.
2Device complexity
If the ECM does not account for transmission load during engine startup, then the control system remains simple, but engine flare and vehicle rollback occur
Solution Approach 1:
The existing transmission load determination capability, originally designed for other control functions, is repurposed to also determine load for engine startup control. This multi-functional use of the transmission load module avoids adding separate complexity while still achieving the benefit of load-aware startup control that prevents engine flare and rollback.
3Productivity
If the target engine speed is not adjusted based on transmission load, then the control algorithm remains simple, but stalls and vibrations occur during startup
Solution Approach 1:
The system changes the target engine speed parameter based on the determined transmission load. By dynamically adjusting this key control parameter according to load conditions, the system prevents stalls and vibrations during startup without requiring complex control algorithms, achieving improved startup reliability through parameter adaptation.
Data Source
AI summary
A control system for an auto-stop/start vehicle includes a transmission load module, a target engine speed module, and an actuator control module. The transmission load module determines a load imposed on an engine through a transmission. The target engine speed module selectively determines a target engine speed during an engine startup event based on the load. The actuator control module controls at least one engine actuator based on the target engine speed during the engine startup event.