CVT Controller Belt Slipping Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional control devices for continuously variable transmissions experience belt slipping during rapid deceleration due to high deceleration levels of the drive wheel, leading to inaccurate gear shift ratio calculations and insufficient belt clamping force.
Innovation Solution
A control device that calculates the actual gear shift ratio using primary and secondary rotation speed sensors, stopping the calculation when the secondary rotation speed falls below a threshold value or when the deceleration level exceeds a designated threshold, preventing belt slipping by maintaining a stable gear shift ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the actual gear shift ratio is calculated continuously using rotation speed sensor values, then the gear shift ratio control accuracy is improved, but belt slipping occurs during rapid deceleration when the calculation is executed with inaccurate sensor data
Solution Approach 1:
The control device performs preliminary checks on the rotation speed sensor value before using it for gear shift ratio calculation. It determines in advance whether the sensor value is within the reliable detection range (above the threshold), and only proceeds with calculation when the condition is satisfied, thereby preventing belt slipping caused by inaccurate calculations during rapid deceleration
Solution Approach 2:
The system implements feedback control by continuously monitoring the rotation speed sensor values and comparing them against the threshold. When the sensor value falls below the threshold during rapid deceleration, the system detects this condition and stops the gear shift ratio calculation, preventing the feedback control from acting on inaccurate data and causing belt slipping
2Reliability
If the gear shift ratio calculation is stopped when rotation speed is low, then belt slipping is prevented, but the control responsiveness deteriorates
Solution Approach 1:
The control system dynamically adjusts its operation based on real-time conditions. The gear shift ratio calculation is continuously performed when rotation speed is above the threshold, ensuring responsive control. When rapid deceleration is detected and rotation speed falls below the threshold, the calculation is temporarily suspended to prevent belt slipping. This dynamic switching between calculation modes optimizes both responsiveness and reliability
Data Source
AI summary
A control device for a continuously variable transmission includes a belt type continuously variable transmission and a controller. The controller is configured to calculate an actual gear shift ratio based on rotation speed sensor values from a primary rotation speed sensor and a secondary rotation speed sensor, and to perform gear shift ratio control using feedback control to converge the actual gear shift ratio to a target gear shift ratio. The controller is further configured to stop calculation of the actual gear shift ratio when one of the rotation speed sensor values is less than a first threshold value determined based on a lower limit value of sensor detection accuracy, and stop calculation of the actual gear shift ratio even when one of the rotation speed sensor values is the first threshold value or greater, when a deceleration level of the drive wheel is a prescribed deceleration level or greater.