Predictive Gear Shift Control for Faster Speed Recovery
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Solution Overview
Problem
Existing vehicle control systems face issues where downshifting prevention on uphill segments can result in low engine rotational speeds, making it difficult for vehicles to quickly recover speed when transitioning to flat or downhill segments, leading to potential driver discomfort.
Innovation Solution
A vehicle control device that selects the current gear stage based on travel resistance and determines the next segment's slope, preventing downshifting only if the vehicle can maintain speed and drive force exceeds resistance, while allowing downshifting when certain conditions are met, such as low stall amounts or kickdown switches being active.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If downshifting is prevented on uphill segments to maintain current gear stage, then fuel efficiency is improved, but engine rotational speed becomes too low and vehicle speed cannot be quickly recovered
Solution Approach 1:
The patent applies dynamics by making the gear shift control adaptive and flexible rather than fixed. The shift control unit dynamically adjusts downshifting prevention based on real-time conditions including next segment slope, current vehicle speed, and engine rotational speed. When the vehicle enters a flat or downhill segment, the system dynamically allows downshifting to restore engine speed, thus resolving the contradiction between fuel efficiency and speed recovery capability.
Solution Approach 2:
The patent changes the control parameter from a static downshifting prevention rule to a conditional parameter-based control system. It monitors multiple parameters (next segment slope angle, current vehicle speed, engine rotational speed, kickdown switch state) and adjusts the gear shift strategy accordingly. This parameter-based approach allows the system to optimize fuel efficiency during uphill segments while enabling quick speed recovery when conditions change.
2Productivity
If downshifting is prevented to maintain drive force above travel resistance, then gear shifts are reduced, but vehicle speed recovery is delayed when entering flat or downhill segments
Solution Approach 1:
The patent applies preliminary action by determining the next travel segment's slope in advance before the vehicle actually enters it. The travel segment determination unit uses map data and GPS information to predict upcoming segments, allowing the shift control unit to proactively adjust gear shift strategy. This preliminary knowledge enables the system to prevent downshifting during uphill segments (reducing gear shifts) while being prepared to allow downshifting before entering flat or downhill segments (ensuring quick speed recovery).
Solution Approach 2:
The patent implements feedback control by continuously monitoring vehicle speed, engine rotational speed, and comparing actual performance against predicted requirements. The shift control unit receives feedback from sensors and adjusts downshifting prevention accordingly. When feedback indicates that engine speed is dropping too low or the vehicle is entering a segment where higher speed is needed, the system feedback-driven allows downshifting, thus resolving the contradiction between reducing gear shifts and enabling timely speed recovery.
3Use of energy by moving object
If the vehicle maintains current gear stage in next segment with drive force exceeding resistance, then fuel consumption is reduced, but engine rotational speed becomes too low affecting performance
Solution Approach 1:
The patent applies dynamics by making the gear stage selection adaptive rather than static. Instead of maintaining a fixed gear stage, the system dynamically selects between maintaining current gear or downshifting based on real-time conditions. The shift control unit continuously evaluates whether the benefits of fuel savings from maintaining current gear outweigh the potential loss of engine power, and adjusts the gear stage accordingly. This dynamic approach resolves the contradiction by optimizing the balance between fuel consumption and engine power based on actual operating conditions.
Data Source
AI summary
This vehicle control device 10 is provided with: a current gear stage selection unit 13 which selects a current gear stage, which is the gear stage of the vehicle in the present travel state; a travel segment determination unit 15 which determines the next travel segment forwards in the direction of travel of the vehicle V; and a shift control unit 17 which, in the case that the current gear stage selection unit 13 has newly selected a target gear stage lower than the current gear stage during travel of the vehicle V in the current gear stage in the current travel segment, if the next travel segment can be traveled in the current gear stage and the amount the vehicle V will lose speed after traveling the current travel segment is less than or equal to a prescribed threshold value, controls shifting of the gear stage such that downshifting from the current gear stage to the target gear stage is suppressed and the current gear stage is maintained. Even in a state in which downshifting is suppressed, if the state of the vehicle the satisfies a prescribed condition, then the shift control unit 17 controls shifting of the gear stage so as to downshift to the target gear stage without suppression of downshifting.