CVT Subtransmission Gear Shift Control for Shock Reduction
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Solution Overview
Problem
The existing continuously variable transmission (CVT) systems with a subtransmission mechanism face limitations in achieving improved power performance and fuel consumption due to excessive restriction in gear position changes, particularly at low vehicle speeds or large throttle openings, which hinders the effective enlargement of the speed ratio range and leads to potential shift shock.
Innovation Solution
A CVT system with a subtransmission mechanism that includes two forward gear positions, where the gear position is dynamically changed based on vehicle operating conditions using a shift control unit to modify the overall speed ratio, allowing the gear position to switch from a first gear position to a second gear position when the speed ratio exceeds a certain threshold, thereby minimizing shift shock and optimizing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gear position of the subtransmission mechanism is changed based on vehicle speed and throttle opening according to a predetermined shift pattern, then the speed ratio range is enlarged, but shift shock occurs in the subtransmission mechanism
Solution Approach 1:
The patent changes the control parameters for gear position switching from fixed vehicle speed and throttle opening thresholds to dynamic parameters based on the speed ratio of the CVT mechanism. By monitoring the CVT speed ratio and comparing it with predetermined reference values, the system determines optimal gear position changes that avoid shift shock while maintaining an enlarged speed ratio range.
Solution Approach 2:
The patent implements a feedback control mechanism where the actual speed ratio of the CVT mechanism is continuously monitored and fed back to the control unit. This feedback enables real-time adjustment of gear position switching decisions, allowing the system to adapt to changing operating conditions and prevent shift shock by making informed gear position changes only when appropriate.
2Object-generated harmful factors
If the gear position change is limited to alleviate shift shock, then shift shock is reduced, but the power performance and fuel consumption performance are not sufficiently improved
Solution Approach 1:
The patent transforms the control strategy by changing from fixed threshold-based gear position control to dynamic control based on CVT speed ratio parameters. This allows the system to fully utilize the subtransmission mechanism's gear position changes for improving power performance during acceleration and fuel consumption during cruising, while avoiding shift shock through intelligent parameter-based decision making.
Solution Approach 2:
The patent introduces dynamic adaptability to the gear position control system by making gear position changes dependent on the real-time speed ratio of the CVT mechanism rather than fixed vehicle speed thresholds. This dynamic approach enables the system to optimize both power performance and fuel consumption across varying operating conditions without being constrained by rigid shift patterns that cause shift shock.
3Object-generated harmful factors
If the gear position change is limited to alleviate shift shock, then shift shock is reduced, but the fuel consumption performance is not sufficiently improved
Solution Approach 1:
The patent changes the control parameters from fixed vehicle speed-based gear shifting to CVT speed ratio-based gear position control. This enables the system to optimize fuel consumption by selecting appropriate gear positions based on the actual operating state of the CVT mechanism, allowing for more efficient energy utilization during high-speed travel while preventing shift shock through intelligent parameter monitoring.
Solution Approach 2:
The patent implements feedback control where the CVT speed ratio is continuously monitored and used to determine optimal gear position changes for fuel efficiency. This feedback mechanism ensures that gear position changes are made only when they will improve fuel consumption performance, rather than following rigid predetermined patterns that may cause unnecessary shift shock or miss fuel-saving opportunities.
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. The mode switch speed ratio is set at a through speed ratio obtained when the speed ratio of the variator is a Highest speed ratio and the gear position of the subtransmission mechanism is the first gear position.