Pneumatic CVT Actuator Control for Ratio Adjustment
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Solution Overview
Problem
Existing CVT transmissions in small vehicles lack active control over transmission ratios, limiting efficiency and drivability, particularly in applications like two-wheelers, three-wheelers, and snowmobiles, where no controlled intervention in gear ratios is possible.
Innovation Solution
A method using a pneumatic actuator connected to a vacuum or pressure source, controlled by a unit determining actual engine speed versus a setpoint speed, allowing for rapid adjustment of CVT transmission ratios to optimize drivability and fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a centrifugal governor is used to adjust the belt position on pulleys, then the transmission ratio can be adjusted based on speed, but no actively controlled or regulated intervention in the gear ratio is possible
Solution Approach 1:
The patent replaces the purely mechanical centrifugal governor system with a hybrid system that incorporates pneumatic actuators controlled by electronic sensors and a control unit. This substitution enables active control and regulation of the transmission ratio while maintaining the mechanical belt-pulley mechanism for actual ratio adjustment.
Solution Approach 2:
The patent introduces pneumatic actuators as intermediaries between the electronic control system and the mechanical pulley system. These actuators convert electrical control signals into mechanical motion, enabling precise control of the belt position and transmission ratio without direct mechanical linkage from the sensor to the pulley.
2Adaptability or versatility
If the axial distance between conical pulleys is changed to adjust transmission ratio, then gear ratios can be varied, but belt tension increases requiring higher axial force
Solution Approach 1:
The patent employs dynamic control of the pneumatic actuator to adjust the axial distance between pulleys progressively and optimally. Rather than applying maximum force immediately, the system dynamically modulates the pneumatic pressure to achieve the required transmission ratio while minimizing peak axial forces and belt tension.
Solution Approach 2:
The patent changes the physical state and parameters of the pneumatic actuator (pressure, flow rate) to control the axial force applied to the pulleys. By precisely controlling these pneumatic parameters, the system achieves the necessary belt tension for transmission ratio adjustment while minimizing excessive forces.
3Speed
If rapid adjustment of CVT transmission is achieved through pneumatic actuation, then response time improves, but system complexity and cost increase
Solution Approach 1:
The patent makes the pneumatic actuator serve multiple functions: it controls the transmission ratio adjustment, maintains belt tension, and responds to varying load conditions. This multi-functionality reduces the need for separate mechanical components and simplifies the overall system despite the added pneumatic control capability.
Solution Approach 2:
The control unit continuously monitors the actual transmission ratio and automatically adjusts the pneumatic actuator to maintain the optimal ratio. This self-regulating system eliminates the need for complex mechanical linkages and manual adjustment mechanisms, achieving rapid response through electronic-pneumatic control loops.
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 method enhances drive efficiency, achieves optimal vehicle properties by enabling controlled and rapid adjustments to transmission ratios, reducing fuel consumption and minimizing losses in CVT transmissions.
Implementation Method 1
If the actual speed is lower than the target speed, the pneumatic actuator is connected to a vacuum source. If the actual speed is greater than a target speed, the pneumatic actuator is connected to a pressure source.
Implementation Method 2
the pneumatic actuator is connected to a vacuum source, preferably an intake area of an internal combustion engine
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a method for controlling a pneumatic actuator (5) of a CVT transmission (1) for changing a conversion ratio of the CVT transmission, comprising the following steps: determining a current actual speed of an internal combustion engine (10); comparing the current actual speed to a target speed of the internal combustion engine, wherein the target speed is determined according to a vehicle speed, wherein, if the actual speed is lower than the target speed, the actuator (5) is connected to a negative-pressure source (9) and wherein, if the actual speed is higher than the target speed, the actuator (5) is connected to a pressure source (14).