CVT Gear Ratio Control for Rotational Oscillation Restraint
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Solution Overview
Problem
Rotational oscillations in the power transmission path of vehicles cause longitudinal oscillations, affecting drivability and ride comfort, and existing technologies fail to effectively address these issues beyond gear shifts.
Innovation Solution
A control device for a transmission with a continuously variable transmission mechanism that adjusts the gear ratio to the high or low side based on rotational oscillations to counteract the oscillations using inertia torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If gear shift control is performed to change transmission gear ratio, then rotational oscillation is restrained, but drivability may deteriorate due to inappropriate timing
Solution Approach 1:
The control device detects rotational oscillation occurrence and rotation speed changes in real-time, using this feedback to determine the appropriate timing for gear shift control. The controller monitors the rotation member's speed variations and triggers gear ratio changes only when rotational oscillation is detected, ensuring feedback-based timing that maintains both oscillation restraint and drivability
Solution Approach 2:
The system dynamically adjusts the transmission gear ratio based on real-time detection of rotational oscillation conditions. Rather than fixed timing, the gear shift control is activated dynamically when oscillation occurs and deactivates when oscillation subsides, allowing the system to adapt to changing operational conditions and maintain optimal drivability
2Stability of the object's composition
If continuously variable transmission mechanism is used, then gear shift smoothness is improved, but rotational oscillation suppression capability is insufficient
Solution Approach 1:
The continuously variable transmission mechanism performs self-service oscillation suppression through automatic gear ratio adjustments. When rotational oscillation is detected, the system automatically changes the transmission gear ratio without requiring external intervention or complex additional components, allowing the transmission to suppress its own oscillations
Solution Approach 2:
The system suppresses rotational oscillation by changing the transmission gear ratio parameter. The controller adjusts this parameter dynamically based on detected oscillation conditions, using parameter variation as the primary control mechanism to achieve oscillation suppression while maintaining the simplicity of the continuously variable transmission structure
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
The solution effectively restrains rotational oscillations by adjusting gear ratios, thereby reducing longitudinal oscillations and improving drivability and ride comfort.
Implementation Method 1
by restraining the decrease or the increase in the rotation speed by an inertia torque generated due to the gear shift of the continuously variable transmission mechanism
Data Source
AI summary
A control device for a transmission is used in a transmission that is provided with a continuously variable transmission mechanism including a primary pulley to which a drive force of a drive source mounted on a vehicle is input, a secondary pulley that transmits the drive force of the drive source to a drive wheel, and an endless annular member that is wound around the primary pulley and the secondary pulley. The control device includes a controller configured to perform a gear shift control of changing a transmission gear ratio of the continuously variable transmission mechanism to a high side when rotational oscillation occurs in a rotation member of the continuously variable transmission mechanism and then the rotational oscillation decreases a rotation speed of the rotation member.