AMT Gear Shift Control for Fuel Economy and Driver Comfort
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Solution Overview
Problem
Large vehicles equipped with Automated Manual Transmission (AMT) face challenges in selecting an optimal gear position that minimizes fuel consumption due to varying resistance at each gear position, leading to inefficiencies in fuel usage.
Innovation Solution
A vehicle control device that determines forward travel segments with different road slopes, estimates travel resistance using slope information, and adjusts gear positions based on current and forward gear positions to optimize fuel consumption, employing a direct gear for improved transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the AMT selects gear positions based on conventional fuel consumption maps, then the gear selection process is simple, but the fuel consumption cannot be optimized due to varying resistance at each gear position
Solution Approach 1:
The system performs preliminary estimation of travel resistance in forward travel segments before the vehicle actually reaches them. By using road slope information and current vehicle speed to predict future resistance conditions, the system can proactively select optimal gear positions in advance, allowing the vehicle to maintain efficient gear selection even when transitioning between segments with different resistance characteristics
Solution Approach 2:
The gear position selection system dynamically adapts to changing road conditions by continuously monitoring road slope information for different travel segments. The system adjusts gear selection based on predicted travel resistance that varies with road grade, vehicle speed, and segment characteristics, transforming a static gear selection approach into a dynamic one that responds to real-time and forecasted conditions
2Use of energy by moving object
If the transmission frequently shifts between direct gear and overdrive gear to optimize fuel consumption, then fuel efficiency improves, but driver discomfort increases due to frequent gear shifts
Solution Approach 1:
The system estimates travel resistance for forward travel segments before the vehicle reaches them, allowing proactive gear position selection. This preliminary assessment enables the transmission to shift gears in advance during optimal conditions rather than reacting to immediate resistance changes, reducing the frequency and abruptness of shifts that would cause driver discomfort
Solution Approach 2:
When the vehicle is approaching a forward travel segment boundary and the estimated time or distance to reach it is within predetermined thresholds, the system skips the upshift to overdrive gear even if currently in direct gear. This allows the vehicle to rush through the transition zone without unnecessary gear changes, maintaining driver comfort while still optimizing fuel consumption in the upcoming segment
3Ease of operation
If the transmission maintains direct gear position for short distances or times, then gear shift frequency decreases, but transmission efficiency is reduced due to higher resistance in direct gear
Solution Approach 1:
The system uses road slope information and vehicle speed to estimate travel resistance in forward segments before reaching them. This preliminary estimation allows the transmission to proactively select overdrive gear in advance when future segments indicate favorable conditions, maximizing the use of efficient gear positions without causing excessive shift frequency
Solution Approach 2:
The system introduces time and distance parameters as thresholds for gear position decision-making. By comparing the estimated time and distance to reach forward travel segments against predetermined thresholds, the system dynamically adjusts whether to upshift to overdrive gear, optimizing the balance between transmission efficiency and gear shift frequency based on specific operational conditions
Data Source
AI summary
A vehicle control device controls a vehicle provided with a transmission having a direct gear and normal gears including an overdrive gear having a lower gear ratio than the direct gear. The device includes a travel segment determination unit which determines a forward travel segment having a different road slope from a current travel segment, a current gear position selection unit that selects a current gear position based on a travel resistance of the vehicle, a forward gear position selection unit that selects a forward gear position based on a travel resistance in the forward travel segment, and a shift control unit that selects whether or not to upshift the transmission based on a situation until the vehicle reaches the forward travel segment, when an upshift to the overdrive gear is newly selected in a case where the current gear position and the forward gear position are the direct gear.