Vehicle Control System for Smooth CVT-Geared Transmission Switching
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Solution Overview
Problem
Existing vehicle control systems face challenges in smoothly changing speed ratios when switching power transmission routes from a geared transmission to a continuously variable transmission, leading to potential shift shocks and discomfort, as well as inefficiencies in achieving target speed ratios.
Innovation Solution
A vehicle control system that initiates the speed change operation of the continuously variable transmission before complete engagement of the friction clutch, while synchronizing the change rate of the speed ratio with the rotational speed change between the input and output shafts, and utilizes a hydraulic actuator to manage clutch engagement pressures for smooth torque transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the speed change operation of the continuously variable transmission is started after completion of clutch engagement, then the torque transmission route switching is clear and simple, but the speed ratio cannot be changed smoothly and response time is delayed
Solution Approach 1:
The control device starts the speed change operation of the continuously variable transmission before the clutch engagement is completed. This preliminary action allows the speed ratio to begin changing while the clutch is still engaging, ensuring smooth transition and eliminating delays in achieving the target speed ratio.
2Device complexity
If the speed ratio is changed stepwise before and after clutch switching, then the torque transmission route switching is straightforward, but the speed change operation cannot be performed smoothly causing shift shock
Solution Approach 1:
The control device ensures continuous speed ratio change by starting the speed change operation before clutch engagement completes and continuing it after engagement. This continuous action eliminates stepwise changes and prevents shift shock, providing smooth speed ratio transition throughout the clutch switching process.
3Reliability
If the speed change operation is delayed until clutch engagement completes, then the torque transmission path is stable, but it takes time to achieve target speed ratio reducing productivity
Solution Approach 1:
The control device initiates the speed change operation before the clutch engagement is completed. This preliminary action reduces the time required to achieve the target speed ratio while maintaining torque transmission stability through continuous control during the engagement process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables smooth speed changes, reduces shift shock, and improves response time by starting the speed change operation before clutch completion, thereby extending the lifespan of friction clutch materials and enhancing overall vehicle performance.
Implementation Method 1
a friction clutch that is brought into engagement to switch a torque transmission route from a route including the geared transmission to a route including the continuously variable transmission
Implementation Method 2
utilizes a hydraulic actuator to manage clutch engagement pressures for smooth torque transitions
Data Source
AI summary
Vehicle control system and method provided to change speed ratio smoothly when switching a power transmission route from a route including a geared transmission to a route including a continuously variable transmission. Vehicle control system applied to a vehicle comprising: continuously variable transmission for changing speed ratio continuously is disposed between input shaft and output shaft; geared transmission is disposed parallel to the continuously variable transmission, and is adapted to establish speed ratio that cannot be established by continuously variable transmission; and friction clutch is brought into engagement to switch torque transmission route from a route including the geared transmission to a route including the continuously variable transmission. Vehicle control system configured to start speed change operation of continuously variable transmission before the friction clutch is brought into engagement completely when switching torque transmission route from the route including the geared transmission to the route including the continuously variable transmission.