Hybrid Vehicle Shift Control System for Acceleration and Fuel Efficiency
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Solution Overview
Problem
Hybrid vehicles with automatic transmission face reduced acceleration feeling due to motor torque decrease with increased engine revolutions, and continuous engine operation leads to fuel inefficiency.
Innovation Solution
A shift control system that uses a fuzzy function calculator, sporty degree calculator, and mode determiner to assess driver inclination through accel position sensor signals, starting the engine for enhanced acceleration when sporty degree exceeds a threshold and stopping it when below a certain level to maintain fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is continuously operated to improve acceleration feeling, then acceleration performance is improved, but fuel efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts engine operation status based on real-time driving conditions and driver behavior patterns. The engine control unit receives signals from multiple sensors (accelerator position sensor, vehicle speed sensor, etc.) and dynamically determines whether to operate the engine based on calculated sporty degree values, transitioning between engine-on and engine-off states to balance acceleration performance and fuel efficiency.
Solution Approach 2:
The system changes the operational parameters of the engine based on detected driving patterns. By calculating the sporty degree from accelerator position and its rate of change, the system adjusts the engine operation state (on/off) as a parameter change, allowing the engine to operate only when high acceleration is genuinely needed rather than maintaining continuous operation.
2Speed
If the engine is started in advance to improve acceleration feeling, then acceleration performance is improved, but fuel is wasted by continuous operation
Solution Approach 1:
The system performs preliminary assessment of driver intent through the sporty degree calculator that analyzes accelerator position and its rate of change before actually starting the engine. This preliminary action allows the system to predict when acceleration will be needed and prepare accordingly, starting the engine only when the calculated sporty degree exceeds the threshold, rather than starting it continuously in advance.
Solution Approach 2:
The system implements a feedback mechanism where the engine control unit continuously monitors accelerator position sensor signals, calculates the sporty degree, and adjusts engine operation status based on this feedback. The feedback loop ensures the engine is started only when the driver's acceleration demand justifies the fuel consumption, preventing unnecessary preliminary engine starts.
3Loss of energy
If kick down shift is performed through motor to maintain EV mode, then fuel efficiency is improved, but acceleration feeling is reduced due to motor torque decrease
Solution Approach 1:
The system introduces an intermediary decision-making mechanism (the sporty degree calculator and mode determiner) that mediates between the conflicting requirements of fuel efficiency and acceleration feeling. This intermediary analyzes driving conditions and determines the appropriate shift execution mode (engine or motor), allowing the system to choose motor-based kick down shift for fuel efficiency when acceleration demand is low, and engine-based kick down shift for acceleration feeling when demand is high.
Data Source
AI summary
A shift control system of a hybrid vehicle with an automatic transmission may include a fuzzy function calculator that receives an accel position sensor (APS) signal that may be an input variable, and outputs a severity value by determining a driver's driving severity value through a plurality of fuzzy rules including a fuzzy function for the APS signal, a sporty degree calculator that may be electrically connected with the fuzzy function calculator and determines a sporty degree corresponding to the severity value, and a mode determiner that may be electrically connected with the sporty degree calculator and determines whether an engine operates in accordance with the sporty degree.