Transmission Upshift Control for Knock-Limited Fuel Economy
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Solution Overview
Problem
Existing transmission control systems inaccurately predict fuel economy shifts due to varying ambient conditions, leading to potential spark knock and decreased fuel economy under certain temperature and humidity conditions.
Innovation Solution
The method involves up-shifting the transmission based on whether engine knock limits spark advance, considering ambient effects on engine knock and ignition timing to accurately assess the impact on fuel flow, using sensors to determine operating conditions and adjust fuel delivery accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the transmission up-shifts based on predicted fuel economy using a ratio map, then fuel economy is improved under cold temperatures and high humidity, but spark knock occurs and fuel economy decreases under hot temperatures and low humidity
Solution Approach 1:
The system changes the prediction parameters by incorporating ambient temperature and humidity into the fuel economy prediction model. Instead of using only a generic ratio map based on speed and torque, the system adjusts prediction parameters according to ambient conditions, allowing accurate predictions across different environmental contexts without causing spark knock.
2Ease of operation
If the transmission up-shifts automatically based on fuel consumption ratio map, then shifting control is simplified, but the system cannot account for ambient effects on engine knock and ignition timing
Solution Approach 1:
The shifting control system is enhanced to perform multiple functions: it continues to use the fuel consumption ratio map for basic shifting decisions while also evaluating ambient temperature and humidity conditions to predict spark knock risk. This multi-functional approach maintains ease of operation while adding adaptability to ambient conditions through integrated knock prediction capability.
3Device complexity
If the system uses a fuel consumption ratio map for shift prediction, then the shifting decision process is simplified, but it incorrectly predicts fuel economy improvement under hot temperatures and low humidity
Solution Approach 1:
The system performs preliminary evaluation of ambient conditions before executing the shift prediction. By assessing temperature and humidity upfront, the system can determine whether the standard ratio map prediction is likely to be accurate or if knock conditions may develop. This preliminary action prevents incorrect predictions while maintaining relatively simple system architecture.
Data Source
AI summary
A method for operating an engine and transmission in a vehicle is described. The method comprises up-shifting the transmission based on whether engine knock limits spark advance at engine conditions after the up-shift. Further, the method may include accounting for differences in fuel types, and their effects on engine knock in future gears.