Mode-Adaptive Gear Selection for Fuel Economy and Travel Speed
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Solution Overview
Problem
Vehicles face challenges in selecting suitable gear stages for different travel modes, leading to suboptimal performance in terms of fuel consumption and travel speed when gear stages are set uniformly across modes.
Innovation Solution
A vehicle control device that determines forward travel sections with varying road gradients and selects gear stages based on driving force and travel resistance characteristics, prioritizing either minimum speed for fuel efficiency or maximum speed for performance, and controls gear shifts accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the vehicle selects gear stages in the same manner in each mode, then the control system is simple, but the vehicle cannot travel suitably for each mode (fuel consumption increases or travel performance deteriorates)
Solution Approach 1:
The gear stage selection is made dynamic by adapting it to different travel modes (first mode for fuel consumption priority, second mode for travel performance priority). The control unit selects gear stages based on the currently active travel mode, allowing the system to optimize performance according to operational requirements rather than using a fixed selection method
Solution Approach 2:
Different gear stage selection strategies are applied to different travel modes. In the first mode, gear stages are selected to minimize fuel consumption, while in the second mode, gear stages are selected to optimize travel performance. This localized optimization for each mode resolves the contradiction between adaptability and complexity
2Loss of energy
If the vehicle shifts to a gear stage optimized for fuel consumption, then fuel consumption is reduced, but the speed becomes smaller than assumed in performance mode
Solution Approach 1:
The system dynamically adjusts gear stage selection based on the active travel mode. When in first mode, gear stages are selected to minimize fuel consumption; when in second mode, gear stages are selected to maximize speed and performance. This dynamic adaptation resolves the contradiction by allowing the system to prioritize one parameter over the other based on operational requirements
Solution Approach 2:
The control unit changes the selection criteria for gear stages based on the travel mode. In fuel consumption priority mode, the selection favors lower gear stages that improve efficiency; in performance priority mode, the selection favors higher gear stages that enable greater speed. This parameter-based selection strategy resolves the speed-fuel consumption trade-off
3Speed
If the vehicle shifts to a gear stage optimized for travel performance, then speed is improved, but fuel consumption is increased than assumed in economy mode
Solution Approach 1:
The gear stage selection dynamically adapts to the active travel mode. In performance priority mode, the system selects gear stages that enable higher speeds; in fuel consumption priority mode, it selects gear stages that optimize efficiency. This dynamic behavior allows the system to achieve high speed when needed while minimizing fuel consumption during economy operation
Solution Approach 2:
The control unit changes gear stage selection parameters based on travel mode requirements. For performance optimization, higher gear stages are selected to enable greater speed; for fuel consumption optimization, lower gear stages are selected to improve efficiency. This parameter adaptation resolves the contradiction between speed and fuel consumption
Data Source
AI summary
In a case where a vehicle is in a first mode in which suppression of fuel consumption is prioritized, a forward gear stage selection unit selects as a forward gear stage a gear stage at which a minimum travelable vehicle speed, which is a minimum speed among a speed of the vehicle at which a driving force indicated by a driving force characteristic is equal to or greater than a travel resistance of a travel resistance characteristic, is highest, and in a case where the vehicle is in a second mode in which improvement of travel performance is prioritized, the forward gear stage selection unit selects as the forward gear stage a gear stage at which a maximum travelable vehicle speed, which is a maximum speed among the speed of the vehicle at which the driving force is equal to or greater than the travel resistance, is highest.