Belt CVT Primary Pressure Control for Wheel Lock Deceleration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional belt-type continuously variable transmissions fail to prevent belt slipping when a tire shows a locking tendency, even on low-friction surfaces, due to insufficient primary pressure during deceleration.
Innovation Solution
A belt-type continuously variable transmission system that calculates and sets a higher primary pressure actual lower limit based on vehicle deceleration and transmission ratio, especially when a locking tendency is detected, to prevent belt slipping, and adjusts the primary pressure lower limit dynamically during low-speed position return shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the primary pressure is reduced during low speed position return shift to improve fuel efficiency, then energy consumption decreases, but belt slipping occurs when a tire shows locking tendency
Solution Approach 1:
The patent implements dynamic adjustment of the primary pressure lower limit based on detected wheel locking tendency. When locking tendency is detected during low speed position return shift, the system raises the primary pressure lower limit from its normal reduced value, thereby preventing belt slipping while maintaining fuel efficiency during normal operation
Solution Approach 2:
The system uses feedback from wheel speed sensors to detect locking tendency and dynamically adjusts the primary pressure control strategy. The transmission controller monitors wheel deceleration and adjusts the primary pressure lower limit accordingly, creating a closed-loop control system that balances fuel efficiency and belt slipping prevention
2Speed
If the primary pressure lower limit is set low during deceleration to enable quick transmission ratio shifts, then shifting speed increases, but belt slipping occurs on low friction surfaces
Solution Approach 1:
The system dynamically adjusts the primary pressure lower limit based on wheel locking tendency detection. During deceleration, when locking tendency is detected, the lower limit is raised to prevent belt slipping, while when no locking tendency is detected, the lower limit remains low to enable quick shifting
Solution Approach 2:
The patent changes the pressure parameter (primary pressure lower limit) based on detected wheel conditions. By adjusting this critical parameter according to wheel locking tendency, the system optimizes both shifting performance and belt slipping prevention under different operating conditions
Data Source
AI summary
A belt-type continuously variable transmission includes a primary pulley, a secondary pulley, and a belt wound around the primary pulley and the secondary pulley. A controller performs a process, when performing a low speed position return shift to shift a transmission ratio toward a lowermost speed position while a vehicle is decelerating. The process includes: calculating a primary pressure actual lower limit, at which the belt actually starts to slip, based on the transmission ratio and a deceleration of the vehicle; setting a lower limit of a setpoint of the primary pressure to the primary pressure actual lower limit; setting the primary pressure actual lower limit higher with a locking tendency of a vehicle wheel detected than that without the locking tendency detected; and setting the primary pressure actual lower limit with the locking tendency detected to increase as the transmission ratio varies toward the lowermost speed position.