CVT Shift Control Optimizing Transmission Efficiency
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Solution Overview
Problem
Existing continuously variable transmission (CVT) systems with subtransmission mechanisms do not optimize fuel consumption performance, as the gear position change conditions are not set to improve fuel efficiency, leaving room for improvement.
Innovation Solution
A CVT system with a subtransmission mechanism that includes two gear positions and a shift control unit, which modifies the overall speed ratio by adjusting the subtransmission gear position and variator speed ratio based on vehicle operating conditions, ensuring the variator operates near the optimal transmission efficiency speed ratio, thereby improving fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gear position of the subtransmission mechanism is changed based on predetermined shift patterns or shock alleviation conditions, then the transmission can operate with a wide ratio range, but the fuel consumption performance is not optimized
Solution Approach 1:
The invention changes the control parameter from predetermined shift patterns to actual transmission efficiency values. The shift control unit determines gear position changes based on real-time transmission efficiency measurements, allowing the system to operate in the gear position that maximizes fuel efficiency under current operating conditions rather than following fixed shift schedules.
Solution Approach 2:
The invention introduces feedback control by measuring actual transmission efficiency and using this information to determine optimal gear position changes. The shift control unit continuously monitors transmission efficiency and adjusts gear positioning decisions based on this feedback, creating a closed-loop control system that optimizes fuel consumption dynamically.
2Adaptability or versatility
If the subtransmission mechanism gear position is changed to maintain a wide ratio range, then the transmission flexibility is improved, but sudden speed ratio changes cause driver discomfort
Solution Approach 1:
The invention applies beforehand cushioning by determining gear position changes based on transmission efficiency rather than abrupt shifts. This approach allows for smoother transitions by selecting gear position changes that maintain optimal efficiency while minimizing sudden disruptions to the transmission ratio, thereby cushioning the impact on driver comfort.
Solution Approach 2:
The invention makes the transmission system dynamic by continuously adapting gear position decisions to real-time transmission efficiency conditions. Rather than fixed gear shift patterns, the system dynamically adjusts gear positioning to maintain optimal efficiency while smoothly managing ratio changes, making the transmission behavior responsive to actual operating conditions.
Data Source
AI summary
When a through speed ratio, which is an overall speed ratio of a variator and a subtransmission mechanism, varies from a larger speed ratio than a mode switch speed ratio to a smaller speed ratio than the mode switch speed ratio, a gear position of the subtransmission mechanism is changed from a first gear position to a second gear position and the speed ratio of the variator is modified to a large speed ratio side. The mode switch speed ratio is set midway between a low speed mode Highest speed ratio and a high speed mode Lowest speed ratio.