CVT Control Device Inertia Phase Timing for Drivability
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Solution Overview
Problem
Conventional control devices for continuously variable transmissions with auxiliary transmissions face issues in maintaining stable transmission input rotation speed during cooperative control, particularly at low vehicle speeds and small input torques, leading to excessive clutch capacity and decreased drivability.
Innovation Solution
A control device that sets a shorter inertia phase time period for the variator relative to the auxiliary transmission mechanism during cooperative control when the input torque is low, ensuring synchronized shifts and preventing excessive clutch capacity, thereby maintaining stable transmission input rotation speed and improving drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a single cooperative shift inertia phase time period is set for both auxiliary transmission mechanism and variator, then the shifts are coordinated, but the clutch capacity of the auxiliary transmission mechanism becomes excessively large and transmission input rotation speed decreases
Solution Approach 1:
The patent divides the cooperative shift inertia phase time period into two separate parameters: a first inertia phase time period for the auxiliary transmission mechanism and a second (shorter) inertia phase time period for the variator. This segmentation allows independent optimization of each component's shift characteristics, preventing excessive clutch capacity while maintaining coordination.
Solution Approach 2:
The patent changes the time period parameter differently for each transmission component during cooperative control. By setting the variator's inertia phase time period shorter than the auxiliary transmission mechanism's time period, the system optimizes the shift coordination and prevents excessive clutch capacity development.
2Speed
If the inertia progress speed of the variator is slow and the inertia progress speed of the auxiliary transmission mechanism is fast, then the auxiliary transmission shifts quickly, but the clutch capacity becomes excessively much and transmission input rotation speed decreases
Solution Approach 1:
The patent applies dynamic control by setting different inertia phase time periods based on the actual shift characteristics of each component. The control system adjusts the time periods to match the varying inertia progress speeds, ensuring that the faster auxiliary transmission mechanism does not develop excessive clutch capacity.
3Measurement precision
If feedback control is used during cooperative control, then the transmission gear ratio is controlled, but feedback control does not function as desired when input torque is small
Solution Approach 1:
The patent applies preliminary action by pre-setting the first and second inertia phase time periods before the cooperative control begins. This preliminary parameter setting ensures that the shift coordination is established in advance, making the control system reliable even when feedback control has limited effectiveness at low input torques.
Data Source
AI summary
A control device for a continuously variable transmission with an auxiliary transmission includes: a cooperative control section being configured to shift the auxiliary transmission mechanism during the first inertia phase time period, and to shift the variator during the second inertia phase time period, when the cooperative control in which an input torque to the continuously variable transmission is equal to or smaller than a predetermined value in the cooperative control is judged, and being configured to shift the auxiliary transmission mechanism during the first inertia phase time period, and to shift the variator during the first inertia phase time period when the cooperative control in which the input torque to the continuously variable transmission is greater than the predetermined value is judged.