Toroidal CVT Clutch Engagement Timing Control
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Solution Overview
Problem
Existing continuously variable transmissions with toroidal and planetary gear components face challenges in performing smooth and quick mode switches between low-speed and high-speed modes, leading to delayed acceleration and reduced performance due to the time required for clutch engagement and disengagement.
Innovation Solution
A control unit is implemented to estimate and account for clutch engagement delays, starting the engagement of one clutch before the toroidal continuously variable transmission reaches the optimal mode switching point, ensuring concurrent engagement of both clutches and adjusting the transmission ratio to minimize speed change periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the transmission ratio is regulated to reach the optimal switching point before clutch engagement, then the mode switching smoothness is improved, but the acceleration response time deteriorates due to clutch engagement delay
Solution Approach 1:
The control unit starts engaging the clutch before the transmission ratio reaches the optimal switching point, anticipating the clutch engagement delay. This preliminary action ensures that the clutch is fully engaged by the time the transmission ratio reaches the optimal point, eliminating acceleration delays while maintaining smooth switching.
Solution Approach 2:
The system compensates for the inevitable clutch engagement delay by initiating the engagement process in advance. The control unit calculates the required lead time and starts clutch engagement accordingly, cushioning against the potential negative effect of delay on acceleration response.
2Speed
If the clutch engagement is started before the transmission ratio reaches the optimal switching point, then the acceleration response is improved, but the mode switching smoothness deteriorates due to potential speed changes
Solution Approach 1:
The control unit continuously monitors the transmission ratio and clutch engagement state, using feedback to adjust the engagement timing and rate. This ensures that the clutch engagement is coordinated with the transmission ratio change, maintaining smooth switching while achieving rapid acceleration response.
Solution Approach 2:
The system dynamically adjusts the clutch engagement process based on real-time transmission ratio and vehicle state. The engagement is not a fixed timing event but a dynamic process that adapts to current operating conditions, allowing smooth transitions while maintaining acceleration performance.
3Reliability
If the clutch engagement time is extended to ensure complete engagement, then the reliability of power transmission is improved, but the productivity of the transmission system deteriorates due to longer mode switching time
Solution Approach 1:
The clutch engagement is initiated before the transmission ratio reaches the optimal switching point, so that the engagement process is completed by the time switching is needed. This preliminary action ensures reliable power transmission without extending the overall mode switching time, as the engagement occurs during the transition period.
Solution Approach 2:
The clutch engagement process is overlapped with the transmission ratio adjustment, maintaining continuous useful action throughout the mode switching. The clutch engages while the transmission ratio is changing, so that power transmission is established without interruption, ensuring both reliability and fast switching.
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 allows for rapid and smooth mode switching, reducing the time required for acceleration and enhancing performance by ensuring the transmission ratio is optimized before clutch engagement is complete, thus preventing delays in acceleration.
Implementation Method 1
an actuator (13) which is a hydraulic actuator and is adapted to displace the support members (trunnions) which support the power rollers (12) in axial directions of pivot shafts provided at both end portions of each of the support members so as to change transmission ratios between the input disk (10) and the output disk (11)
Implementation Method 2
a low-speed clutch (7) which has a friction material on a friction member and engages or disengages based on contact between the friction member and a fastened member
Data Source
AI summary
A control unit is imparted a function in which the engagement of a high-speed clutch which had been in disengagement until then is started (or the energization of a high-speed clutch solenoid switch valve is put to ON) before a change-speed of a toroidal continuously variable transmission has reached an optimal value for performance of a mode switch (a point A, for example, 0.46 in a speed increasing ratio) or at a point B (for example, 0.6 in the speed increasing ratio). As a result of this, the problem can be solved.