CVT Piston Control for Altitude-Adaptive Pulley Diameter
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Solution Overview
Problem
Mechanically controlled continuously variable transmissions (CVTs) face limitations in power efficiency due to frictional losses, noise, vibrations, and high fuel consumption, especially at high rotational speeds, and require additional components for pneumatic or hydraulic control, which increase weight and cost, while lacking on-the-fly configuration adjustments based on operating conditions.
Innovation Solution
A method for operating a CVT that includes a piston connected to the driving pulley, controlled by a unit that adjusts the pulley's diameter based on altitude, atmospheric pressure, throttle position, and engine speed, using a control map to optimize piston force for different modes of operation, including a pneumatic or hydraulic actuation system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If mechanical control is used in CVT, then the structure is simple, but power efficiency is poor due to frictional losses
Solution Approach 1:
The patent replaces the traditional mechanical control system with an electronic control system that uses a piston to adjust the driving pulley diameter. The electronic control unit receives signals from sensors and controls the piston position electronically, eliminating frictional losses associated with mechanical linkages and improving power efficiency while maintaining structural simplicity.
Solution Approach 2:
The patent employs a piston connected to the driving pulley that can be actuated to change the effective diameter of the driving pulley. This pneumatic/hydraulic mechanism provides efficient force transmission with minimal friction, allowing for precise control of the CVT ratio while improving power efficiency compared to traditional mechanical control systems.
2Device complexity
If mechanical control is used in CVT, then the structure is simple, but noise and vibrations increase at high speeds
Solution Approach 1:
The electronic control system replaces mechanical linkages that generate noise and vibrations at high speeds. The electronic control unit communicates with the piston actuator through electrical signals rather than mechanical connections, significantly reducing noise and vibrations while maintaining the simplicity of the overall control structure.
3Device complexity
If mechanical control is used in CVT, then the structure is simple, but fuel consumption increases at high RPM
Solution Approach 1:
The electronic control system eliminates the energy losses associated with mechanical friction in linkages and bearings. By using electronic signals to control the piston position, the system reduces parasitic power consumption, thereby lowering fuel consumption at high RPM while keeping the control structure simple.
4Adaptability or versatility
If pneumatic or hydraulic control is added to CVT, then control flexibility improves, but weight increases due to additional components
Solution Approach 1:
The patent integrates the piston and hydraulic/pneumatic system into the existing CVT structure, where the same system serves multiple functions: controlling the driving pulley diameter, providing force multiplication, and enabling precise electronic control. This multi-functionality approach allows control flexibility without adding significant weight from separate control components.
5Adaptability or versatility
If pneumatic or hydraulic control is added to CVT, then control flexibility improves, but cost increases
Solution Approach 1:
The integrated piston system performs multiple functions within a single component structure, reducing the total number of parts that need to be manufactured and assembled. The electronic control unit can be integrated with the existing vehicle's control systems, sharing common components and reducing overall manufacturing cost while maintaining control flexibility.
Solution Approach 2:
The patent combines the control function with the existing CVT pulley mechanism by integrating the piston directly into the driving pulley assembly. This merging of functions eliminates the need for separate control mechanisms, reducing component count, simplifying manufacturing, and lowering cost while achieving improved control flexibility.
6Device complexity
If mechanical control is used in CVT, then the structure is simple, but on-the-fly configuration adjustments are limited
Solution Approach 1:
The patent implements a dynamic control system where the electronic control unit can adjust the piston position in real-time based on signals from sensors that monitor operating conditions. This allows the CVT configuration to be dynamically adjusted on-the-fly to optimize performance for different driving conditions, transitioning from static mechanical control to dynamic electronic control while maintaining structural simplicity.
Solution Approach 2:
The system incorporates sensors that provide feedback to the electronic control unit about operating conditions such as engine speed, vehicle speed, and throttle position. The control unit processes this feedback information and adjusts the piston position accordingly, enabling automatic on-the-fly configuration adjustments that optimize CVT performance for varying operating conditions while keeping the control structure relatively simple.
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 approach enhances power efficiency, reduces noise and vibrations, allows for fast configuration adjustments, and eliminates the need for additional weighty components, improving fuel efficiency and operational reliability across varying conditions.
Implementation Method 1
A piston is operatively connected to the driving pulley for applying a piston force to the driving pulley when actuated, and thereby changing an effective diameter of the driving pulley
Implementation Method 2
the CVTs are mechanically controlled by means of centrifugal weights (usually on the driving side) acting against the force of a spring to provide the desired gear ratios
Data Source
AI summary
A method of operating a vehicle at different altitudes. The vehicle has an engine, a throttle valve and a throttle operator. A continuously variable transmission has a driving pulley connected to the engine, a driven pulley, and a belt operatively connecting therebetween. A ground engaging member is operatively connected to the driven pulley. A piston is connected to the driving pulley. A control unit controls actuation of the piston and the piston force. The method includes determining an altitude and/or an atmospheric pressure, a driven pulley speed, and at least one of the throttle operator position and the throttle valve position. The piston is selectively actuated based on the altitude and/or the atmospheric pressure. The piston force is controlled based on the driven pulley speed, and at least one of: the throttle operator position and the throttle valve position. Vehicles and other methods of operation thereof are also disclosed.