CVT Thrust Applying Mechanism for Reduced Pump Capacity
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Solution Overview
Problem
Conventional continuously variable transmissions face limitations in fluid-pump capacity due to the need for high fluid pressures to achieve sufficient thrust differences between pulleys at low and high speed ratios, leading to increased fuel consumption, especially when climbing slopes or running at high speeds.
Innovation Solution
A continuously variable transmission system with a primary and secondary pulley, a control valve unit, and a thrust applying mechanism that uses a combination of spring forces and fluid pressures to adjust groove widths, where the spring force is set higher than necessary thrust, and fluid pressures are optimized to reduce the fluid-pump capacity by using a second fluid pressure force opposing the spring force, allowing for sufficient thrust difference at lower pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high fluid pressure is applied to achieve sufficient thrust difference between pulleys, then the thrust difference is sufficient, but the fluid-pump capacity increases leading to higher fuel consumption
Solution Approach 1:
The patent applies a second fluid pressure force in the opposite direction to the spring force, creating a counterbalancing effect. This allows the system to achieve sufficient thrust difference between pulleys without requiring excessively high fluid pressure, thereby reducing the fluid-pump capacity and fuel consumption while maintaining adequate belt-clamping force.
Solution Approach 2:
The patent optimizes the parameters of fluid pressure by introducing a second fluid pressure force that acts in opposition to the spring force. This parameter adjustment enables the system to achieve the necessary thrust difference with lower overall fluid pressure requirements, reducing energy consumption.
2Force
If spring force is increased to provide sufficient thrust, then the thrust is adequate, but the fluid pressure must be even higher to overcome the spring force
Solution Approach 1:
The second fluid pressure force acts in the opposite direction to the spring force, effectively counterbalancing it. This allows the system to utilize the spring force productively without requiring additional high fluid pressure to overcome it, thereby achieving adequate thrust with reduced fluid pressure requirements.
Solution Approach 2:
The fluid pressure system serves multiple functions: it provides the primary thrust force through the first fluid pressure force and simultaneously counterbalances the spring force through the second fluid pressure force. This multi-functionality allows the spring force to be fully utilized without increasing fluid pressure requirements.
3Device complexity
If fluid pressure force is used alone to narrow groove widths, then the mechanism is simple, but the thrust difference is insufficient at extreme speed ratios
Solution Approach 1:
The patent combines multiple force components (spring force, first fluid pressure force, and second fluid pressure force) into a unified thrust applying mechanism. This combination allows the system to achieve sufficient thrust difference at extreme speed ratios while maintaining a relatively simple overall structure that integrates all force-generating elements.
Solution Approach 2:
The thrust applying mechanism is segmented into distinct force-generating components: a spring force mechanism and two fluid pressure force mechanisms acting in different directions. This segmentation allows each component to be optimized for its specific function while working together to achieve the required thrust difference.
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 configuration enables sufficient thrust difference between pulleys at various speed ratios with lower fluid pressure, reducing the necessary fluid-pump capacity and improving fuel efficiency by allowing the fluid-pump to operate with reduced pressure, thereby enhancing the overall performance of the transmission system.
Implementation Method 1
a spring force of the spring
Implementation Method 2
a first fluid pressure force obtained based on a first fluid pressure... and a second fluid pressure force... The first fluid pressure force and the second fluid pressure force
Data Source
AI summary
A continuously variable transmission has a primary pulley having a primary movable sheave that is capable of moving to change a groove width of the primary pulley, and a secondary pulley having a secondary movable sheave that is capable of moving to change a groove width of the secondary pulley. Endless flexible members are engaged with the primary pulley and the secondary pulley to transmit torque therebetween. At least one of the pulleys has a thrust applying mechanism that is capable of applying spring force and first fluid pressure force to the movable sheave of the pulley so as to narrow the groove width thereof and generating second fluid pressure force opposite to the spring force and the first fluid pressure force.