CVT Control Device V-Belt Temperature Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing V-belt continuously variable transmission controllers detect temperature indirectly, leading to delayed and imprecise temperature readings, resulting in low precision of speed-reduction ratio control, limited usage range at low output speeds, and compromised starting acceleration performance.
Innovation Solution
A control device for a continuously variable transmission that uses an oil pressure control unit and rotation speed sensors to set and adjust the speed-reduction ratio based on predetermined maps, eliminating the need for direct temperature sensors by determining the V-belt's temperature state through primary pulley rotation speed and vehicle speed correlations, allowing precise control and extended usage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a non-contact temperature sensor is used to detect V-belt temperature, then the V-belt temperature can be monitored, but the detection is indirect causing delay and lower precision compared to actual temperature
Solution Approach 1:
The patent uses oil pressure as an intermediary parameter to indirectly control and infer V-belt temperature conditions. By controlling the oil pressure supplied to the primary and secondary pulleys, the system manages heat generation in the V-belt without requiring direct temperature measurement, thus avoiding detection delays and precision issues
Solution Approach 2:
The system uses readily available sensors (rotation speed sensors and oil pressure control) that are already part of the CVT system to achieve temperature management, rather than adding specialized temperature sensing equipment. The existing system components serve the additional function of temperature control
2Temperature
If the speed-reduction ratio is reduced to suppress V-belt heat generation, then the V-belt temperature is controlled, but the usage range of speed-reduction ratio at low output speed is limited
Solution Approach 1:
The patent dynamically adjusts the speed-reduction ratio based on real-time operating conditions including rotation speed and elapsed time. The control strategy allows the system to operate at lower speed-reduction ratios longer during transient conditions, then shift to higher ratios when temperature thresholds are approached, creating a dynamic adaptation that expands the usable speed-reduction ratio range
Solution Approach 2:
The system uses predetermined maps and elapsed time calculations to anticipate temperature rise before it occurs. By calculating the first predetermined rotation speed at which the V-belt reaches the first limiting temperature and monitoring elapsed time, the controller proactively adjusts the speed-reduction ratio to prevent excessive heat generation while maintaining expanded operational range
3Temperature
If the speed-reduction ratio is controlled to maintain V-belt temperature below limiting temperature, then temperature control is achieved, but the starting acceleration performance of vehicle is compromised
Solution Approach 1:
The patent implements periodic monitoring and adjustment of the speed-reduction ratio based on elapsed time intervals. The controller calculates elapsed time since the rotation speed exceeded the first predetermined rotation speed, and periodically adjusts the speed-reduction ratio between the first and second ratios based on whether the elapsed time exceeds the first predetermined time, allowing temporary performance optimization while maintaining temperature safety
Solution Approach 2:
The system changes the speed-reduction ratio parameter dynamically between two predetermined values (first and second speed-reduction ratios) based on operating conditions. By switching between these discrete parameter values rather than continuously adjusting, the system optimizes both temperature control and acceleration performance
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
This solution enables high-precision temperature control of the V-belt, expands the usage range of the speed-reduction ratio at low output speeds, and improves starting acceleration performance by accurately managing the V-belt's temperature without the need for costly temperature sensors.
Implementation Method 1
an oil pressure control unit which supplies an oil pressure to the primary pulley and secondary pulley based on a command signal indicative of a target speed-reduction ratio
Implementation Method 2
a sensor which detects a rotation speed of the primary pulley
Data Source
AI summary
A control device for controlling a continuously variable transmission (5) is disclosed. The control device has an oil pressure control unit (100) which supplies an oil pressure to a primary pulley (10) and secondary pulley (11) based on a command signal indicative of a target speed-reduction ratio, a sensor (26) which detects a rotation speed (Np1) of the primary pulley (26), and a controller (20) which transmits the command signal indicative of the target speed-reduction ratio to the oil pressure control unit (100). The controller is programmed to set the target speed-reduction ratio to a first speed-reduction ratio (R1); calculate a first predetermined rotation speed (N1) of the primary pulley at which the V-belt reaches a first limiting temperature (T1) at the first speed-reduction ratio (R1); calculate a first elapsed time after the detected rotation speed (Np1) of the primary pulley exceeds the first predetermined rotation speed (N1); maintain the first speed-reduction ratio (R1) when the first elapsed time is equal to or less than a first predetermined time; and set the target speed-reduction ratio to a second speed-reduction ratio (R2) smaller than the first speed-reduction ratio (R1) when the first elapsed time exceeds the first predetermined time. At the second speed-reduction ratio (R2), the temperature of the V-belt should become equal to or less than the first limiting temperature (T1) throughout the permitted rotation speed region of the primary pulley. Thus, starting acceleration performance of the continuously variable transmission is enhanced.