CVT Controller Using Torque Maps to Prevent Interference
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Solution Overview
Problem
Existing controllers for continuously variable transmissions (CVT) face interference between engine output control and speed ratio control during constant vehicle speed, requiring complex mathematical modeling and time-consuming adjustments.
Innovation Solution
A simpler CVT controller with three main components: basic speed ratio setting, adjustment speed ratio setting, and speed ratio control, using a target torque interrelated value to prevent interference by progressively adjusting the speed ratio based on operating areas defined by a target torque interrelated value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mathematical modeling of vehicle and control program are used to prevent interference between engine output control and speed ratio control, then the interference is prevented, but the device complexity and adjustment time increase
Solution Approach 1:
The patent changes the control parameters from complex mathematical models to simple lookup tables (maps) that store predetermined speed ratio adjustments. The ECU refers to these maps based on throttle opening and vehicle speed to determine speed ratio corrections, eliminating the need for complex real-time calculations while maintaining effective interference prevention.
Solution Approach 2:
The patent creates simplified representations (maps) that copy the essential relationships between throttle opening, vehicle speed, and speed ratio adjustments. These maps pre-store the control characteristics that would otherwise require complex mathematical modeling, allowing the system to achieve the same control objectives with much simpler data structures.
2Reliability
If mathematical modeling and control programs are implemented, then interference prevention is achieved, but adjustment time and labor costs increase
Solution Approach 1:
The patent performs the complex control logic adjustments in advance by pre-calculating and storing speed ratio corrections in lookup tables during the mapping process. This preliminary action eliminates the need for time-consuming real-time mathematical modeling and program adjustments, as the ECU simply retrieves pre-determined values during operation.
3Device complexity
If basic speed ratio control based on vehicle speed is used, then simple control is achieved, but interference from engine output control during constant speed travel cannot be prevented
Solution Approach 1:
The patent introduces speed ratio correction values as an intermediary element between the basic speed ratio control and the final speed ratio. These correction values, retrieved from maps based on throttle opening and vehicle speed, mediate the interaction between engine output control and CVT speed ratio control, preventing interference while maintaining the simplicity of the basic control structure.
Data Source
AI summary
A controller for a continuously variable transmission (CVT) mounted in a vehicle. The controller includes a first setting unit for setting a basic speed ratio of the CVT; a second setting unit for setting an adjustment speed ratio of the CVT; and a control unit for controlling the CVT based on the basic speed ratio and adjustment speed ratio. The second setting unit includes an increasing unit for progressively increasing the adjustment speed ratio according to a increase in a target torque interrelated value in a first operating area, and a decreasing unit for progressively decreasing the adjustment speed ratio according to a decrease in the target torque interrelated value in a second operating area. Between the first operating area and the second operating area, the second setting unit maintains the adjustment speed ratio that is set finally.