V-belt CVT Actuator Thrust Correction
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Solution Overview
Problem
The existing V-belt continuously variable transmission systems face challenges in improving followability of target shift transmission control, particularly due to the varying thrust direction and magnitude from both the centrifugal shift mechanism and the actuator, which are influenced by engine speed and throttle opening, leading to inefficiencies in gear ratio control.
Innovation Solution
Incorporating a control unit with actuator thrust determination means, correction value determination means, and thrust correction means to adjust the actuator thrust based on current and target engine speeds, throttle openings, and gear ratio modes, using a map-based approach to fine-tune the correction values for improved control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If PID control with gear ratio feedback only is used, then the control system is simple, but the followability of target shift transmission control deteriorates
Solution Approach 1:
The patent introduces multiple feedback loops beyond simple gear ratio feedback. It includes engine speed feedback (comparing actual engine speed with target engine speed), throttle opening feedback, and driven shaft rotational speed feedback. These multiple feedback signals are processed by the control unit to determine appropriate actuator thrust, significantly improving the followability of target shift transmission control while maintaining reasonable system complexity.
2Measurement precision
If the actuator thrust is increased to improve control precision, then the followability improves, but the actuator size and cost increase
Solution Approach 1:
The patent replaces a purely mechanical control system with an electromechanical control system. Instead of using a large mechanical actuator, the invention uses a small electromagnetic actuator whose thrust is precisely controlled through electronic feedback loops. The control unit calculates the required actuator thrust based on engine speed deviation, throttle opening, and other parameters, allowing a small actuator to achieve the control precision that would otherwise require a much larger mechanical system.
3Weight of moving object
If the centrifugal shift mechanism is added to reduce actuator thrust, then the actuator can be miniaturized, but the control followability deteriorates due to varying thrust directions
Solution Approach 1:
The patent employs dynamic control by continuously adjusting the actuator thrust based on real-time operating conditions. The control unit calculates the required actuator thrust dynamically using PID control based on engine speed deviation, and applies correction values based on throttle opening and driven shaft speed. This dynamic adjustment compensates for the varying thrust directions from the centrifugal shift mechanism, maintaining excellent followability of target shift transmission control while enabling actuator miniaturization.
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 enhances the followability of target shift transmission control by accurately adjusting actuator thrust in response to throttle manipulations and engine conditions, reducing overshoot and improving alignment with target engine speed characteristics across different gear modes.
Implementation Method 1
a centrifugal shift mechanism that is configured to include a plurality of centrifugal weights arranged around a rotational axis of the movable sheave and that is configured to axially move the movable sheave according to centrifugal force acting on the centrifugal weights in association with rotation of the drive shaft
Data Source
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AI summary
In a vehicle V-belt continuously variable transmission including also a centrifugal shift mechanism (72) in addition to an actuator (80) for driving a movable sheave (62), a control unit (100) for controlling actuation of the actuator (80) is provided with actuator thrust determination means (112) for determining thrust provided by the actuator (80) based on the present engine speed and a target engine speed, correction value determination means (113) for determining a correction value of the thrust provided by the actuator (80) based on at least a throttle opening, and thrust correction means (114) for correcting the thrust provided by the actuator (80) and determined by the actuator thrust determination means (112) based on the correction value determined by the correction value determination means (113).