CVT Acceleration Control Using Load-Based Transmission Ratios
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Solution Overview
Problem
Current continuous variable transmission (CVT) powertrains experience delays and inefficiencies in responding to acceleration demands, as they often operate at peak power, which is not the most energy-efficient region and results in harsh and unpredictable responses.
Innovation Solution
A method that applies an initial transmission ratio to provide immediate acceleration while increasing engine load, using a loading transmission ratio determined by vehicle acceleration to maintain acceleration by progressively increasing engine load or power output, with the ability to adjust ratios based on engine load and speed to optimize operation at a full load point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine speed is forced to peak power prior to changing transmission ratio, then acceleration demand is met, but response delay occurs and the response becomes harsh and unpredictable
Solution Approach 1:
The control system pre-calculates and pre-positions the transmission ratio in anticipation of acceleration demand, so that when the accelerator is pressed, the transmission ratio is already optimized for immediate acceleration without waiting for engine speed to reach peak power first
Solution Approach 2:
The transmission ratio is made dynamically adjustable in real-time based on actual acceleration demand and engine operating conditions, allowing continuous optimization of the acceleration response rather than using fixed pre-determined ratios
2Power
If peak power is used to provide acceleration, then acceleration demand is met, but energy efficiency deteriorates as peak power is not the most efficient operating region
Solution Approach 1:
The control system changes the operating parameters by selecting transmission ratios that allow the engine to operate in high-efficiency regions while still meeting acceleration demands, rather than always operating at peak power where efficiency is lower
Solution Approach 2:
The system dynamically adjusts the transmission ratio based on real-time monitoring of engine operating conditions, allowing the engine to operate efficiently across varying load conditions while maintaining adequate acceleration performance
3Speed
If transmission ratio is changed to provide acceleration, then vehicle acceleration is achieved, but engine load management becomes complex requiring continuous adjustment
Solution Approach 1:
The control system continuously monitors engine load, vehicle acceleration, and transmission ratio, using feedback loops to automatically adjust the transmission ratio to optimal values, thereby managing the complexity through automated control rather than manual intervention
Solution Approach 2:
The transmission control system is designed to perform multiple functions simultaneously: managing engine load, optimizing acceleration, maintaining efficiency, and adapting to different driving conditions, all through a single integrated control mechanism
Data Source
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Figure 3
Figure 4A~4C
AI summary
Disclosed is a method for controlling the acceleration of a vehicle, comprising: receiving a demand for acceleration from an operator input device; applying an initial transmission ratio to provide a vehicle acceleration whilst maintaining a current engine speed; applying a loading transmission ratio to increase the output from the engine, wherein the loading transmission ratio is determined using the vehicle acceleration.