CVT Gear Shift Control Torque Reduction Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Continuously variable transmissions (CVTs) fail to replicate the snappy gear shift feeling of stepped transmissions, even when using pseudo-stepped upshift modes, due to inadequate torque reduction during upshifting, which affects the vehicle's forward-reverse acceleration.
Innovation Solution
A gear shift control device for CVTs that implements pseudo-stepped upshift control with a torque reduction command starting before actual upshifting, using a prescribed torque reduction amount greater than inertia torque, and adjusting based on engine load demand, to mimic the snappy feeling of stepped transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pseudo-stepped upshift control is implemented in CVT, then gear shifting is performed in steps to mimic stepped transmission, but snappy gear shift feeling cannot be sufficiently obtained due to inadequate torque reduction
Solution Approach 1:
The torque reduction command is issued in advance before the upshift actually occurs. The control device calculates the required torque reduction amount based on vehicle speed and accelerator opening, and issues the torque reduction command at a timing that allows the torque to be reduced before the upshift completes, creating the snappy pullback feeling characteristic of stepped transmissions.
Solution Approach 2:
The control device dynamically adjusts the torque reduction amount as a parameter based on operating conditions (vehicle speed and accelerator opening). By changing the torque parameter in conjunction with the upshift, the system creates the desired snappy gear shift feeling while adapting to different driving conditions.
2Stability of the object's composition
If torque reduction is implemented only from inertia phase to negate inertia torque, then upshift smoothness is maintained, but pullback of vehicle forward-reverse G cannot be generated
Solution Approach 1:
Instead of waiting for the inertia phase to begin torque reduction, the control device issues the torque reduction command in advance during the torque phase. This preliminary action creates the pullback effect before the upshift completes, generating the snappy feeling while still managing the transition smoothly.
Solution Approach 2:
The torque reduction acts as a cushioning measure that prepares the vehicle for the upcoming upshift by reducing torque before the inertia phase. This beforehand cushioning creates the desired pullback feeling while preventing excessive shock during the actual upshift transition.
3Loss of time
If torque reduction command timing is delayed until upshift start, then response time is reduced, but torque reduction amount becomes insufficient to create pullback effect
Solution Approach 1:
The control device issues the torque reduction command in advance before the upshift actually starts. By performing the preliminary action of torque reduction before the upshift, the system ensures both sufficient torque reduction amount and appropriate timing to create the pullback effect.
Solution Approach 2:
The control device uses feedback from vehicle speed and accelerator opening sensors to determine the appropriate torque reduction amount and timing. This feedback mechanism ensures that the torque reduction is sufficient to create the pullback effect while adapting to real-time operating conditions.
Data Source
AI summary
A gear shift control device for a continuously variable transmission of a vehicle is configured to steplessly and continuously change and output a rotation speed of an engine. The gear shift control device includes a gear shift control unit and a torque control command unit. The gear shift control unit is configured to implement a pseudo-stepped upshift control to change a gear shift ratio in steps when upshifting the continuously variable transmission. The torque control command unit is configured to output a torque reduction command so as to reduce an engine torque in conjunction with the pseudo-stepped upshift control so that reduction of the engine torque starts before a point in time when an actual gear shift ratio starts changing in response to an upshift command.