CVT Secondary Pulley Clamping Force Learning for Slip Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control systems for continuously variable transmissions (CVTs) face challenges in optimizing clamping force management to prevent chain slippage while minimizing hydraulic pressure, which affects fuel efficiency and durability due to individual variance and aged deterioration.
Innovation Solution
A control apparatus that includes a learning value acquiring unit to decrease the secondary pulley's clamping force while keeping the transmission ratio and input torque constant, acquiring a learning value at the maximum clamping force ratio, and adjusting the target clamping force based on this value to prevent slippage and reduce excess hydraulic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamping force of the secondary pulley is increased to prevent chain slippage, then the reliability of power transmission is improved, but the hydraulic pressure loss increases affecting fuel efficiency
Solution Approach 1:
The system dynamically adjusts the clamping force parameter of the secondary pulley based on learned characteristics of the CVT system. By changing this parameter adaptively rather than using a fixed high value, the system prevents slippage when necessary while minimizing hydraulic pressure loss during normal operation, thus resolving the contradiction between reliability and energy efficiency
Solution Approach 2:
The control apparatus implements a feedback mechanism where the learning value acquiring unit continuously monitors the relationship between primary and secondary pulley clamping forces. This feedback loop allows the system to learn the optimal clamping force ratio and adjust the secondary pulley clamping force accordingly, preventing slippage while minimizing excess hydraulic pressure and associated energy losses
2Reliability
If the clamping force is increased to account for aged deterioration and individual variance, then the durability and reliability are improved, but the fuel efficiency deteriorates due to continuous high hydraulic pressure
Solution Approach 1:
The system performs preliminary learning action during normal operation to establish the optimal clamping force relationship between primary and secondary pulleys. This preliminary characterization allows the control system to subsequently operate with minimal necessary clamping force rather than continuously high pressure, improving fuel efficiency while maintaining reliability under aged deterioration and individual variance conditions
Solution Approach 2:
The system adapts the clamping force parameter based on learned system characteristics that account for aged deterioration and individual variance. By dynamically adjusting this parameter rather than maintaining a consistently high value, the system ensures reliable slippage prevention while minimizing the hydraulic pressure required, thus improving fuel efficiency
Data Source
AI summary
A control apparatus for a continuously variable transmission includes a primary-pulley clamping force acquiring unit that acquires a clamping force of a primary pulley, a secondary-pulley clamping force acquiring unit that acquires a clamping force of a secondary pulley, an input torque acquiring unit that acquires a torque applied to the primary pulley, a transmission ratio acquiring unit that acquires a transmission ratio, a learning value acquiring unit, and a controller. When a learning condition is satisfied, the learning value acquiring unit decreases the clamping force of the secondary pulley while the transmission ratio and the input torque are kept substantially constant, and acquires, as a learning value, the clamping force of the secondary pulley at which a clamping force ratio is maximum. The controller adjusts a target clamping force of the secondary pulley on the basis of the learning value.