CVT Control Apparatus Preventing Transfer Element Slippage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing control apparatus for drive-force transmitting apparatuses in vehicles experiences slippage issues due to excessive torque input during sudden reductions in drive wheel rotational speed, particularly when transitioning between gear ratios, leading to reduced thrust and potential slippage of the transfer element in the continuously-variable transmission mechanism.
Innovation Solution
A control apparatus that dynamically adjusts the target gear ratio of the continuously-variable transmission mechanism based on the state of drive wheel slip, setting it to the highest gear ratio when not slipping and to the actual gear ratio at the onset of slip, and includes a thrust applier to maintain clamping force, preventing slippage by managing torque transmission through engagement devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the continuously-variable transmission mechanism executes a shift-down action to change the gear ratio to the highest gear ratio during switching control operation, then the responsiveness of the switching control is improved, but the thrust applied to the primary pulley is reduced causing slippage of the transfer element
Solution Approach 1:
The control apparatus prevents the shift-down action from being executed when drive wheel slippage is detected, before the slippage can cause excessive torque transmission that would reduce the clamping force and cause transfer element slippage. This preliminary prevention action avoids the harmful sequence of events.
Solution Approach 2:
The invention converts the potentially harmful situation of drive wheel slippage into a beneficial control state by detecting the slippage condition and using it to modify the switching control operation, preventing the shift-down action that would otherwise cause transfer element slippage. The harmful drive wheel slippage condition becomes useful information for preventing a more serious transmission failure.
2Adaptability or versatility
If the gear ratio of the continuously-variable transmission mechanism is changed during switching control operation, then the adaptability of the drive-force transmitting apparatus is improved, but the excessive torque from drive wheel slippage causes reduction of clamping force leading to transfer element slippage
Solution Approach 1:
The control apparatus dynamically adjusts the switching control operation based on the detected drive wheel slippage condition. When slippage is detected, the control operation is modified to prevent shift-down actions, thereby dynamically adapting the transmission behavior to maintain reliable torque transmission while preserving the ability to perform normal adaptive switching when conditions permit.
3Adaptability or versatility
If the thrust applied to the primary pulley is reduced during gear ratio change, then the gear ratio adjustment is achieved, but the transfer element slips on the pulleys due to insufficient clamping force
Solution Approach 1:
The control apparatus applies a preliminary anti-action by preventing the shift-down action (which would reduce thrust) from being executed when drive wheel slippage is detected. This preemptive measure counteracts the potential reduction of clamping force before it can cause transfer element slippage, maintaining the necessary grip stability.
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
The solution effectively prevents or reduces slippage of the transfer element by adjusting gear ratios and maintaining adequate clamping force, ensuring efficient torque transmission and vehicle stability even under conditions of drive wheel slip.
Implementation Method 1
a thrust which is applied to the primary pulley and which serves as a clamping force to clamp the transfer element
Data Source
AI summary
A control apparatus for a vehicle drive-force transmitting apparatus including a gear mechanism and a continuously-variable transmission mechanism provided in respective first and second drive-force transmitting paths. The control apparatus sets a target gear ratio of the continuously-variable transmission mechanism during a switching control operation that is executed to switch between (i) a first state in which the first drive-force transmitting path is established and (ii) a second state in which the second drive-force transmitting path is established, such that, when drive wheels are not being slipped, the target gear ratio is set to a highest gear ratio of the continuously-variable transmission mechanism, and such that, when the drive wheels are being slipped, the target gear ratio is set to an actual gear ratio at a point of time at which the drive wheels start being slipped.