Continuously Variable Transmission Using Segmented Gear Sets
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Solution Overview
Problem
Existing continuously variable transmissions using auxiliary shift apparatuses with planetary gear sets are complex, heavy, and inefficient, leading to deteriorated mountability and fuel economy due to increased weight and complexity.
Innovation Solution
A continuously variable transmission system utilizing multiple externally-meshed gear sets and a variable shift apparatus to achieve two forward speeds and one reverse speed, reducing weight and complexity by eliminating the need for a planetary gear set, with a primary and secondary pulley system and clutches to adjust speed ratios continuously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a planetary gear set is used in the auxiliary shift apparatus, then two forward speeds and one reverse speed can be realized, but the structure becomes complex and the volume and weight increase
Solution Approach 1:
The transmission system is divided into multiple externally-meshed gear sets (first speed gear set, second speed gear set, reverse speed gear set) that operate independently but coordinate through clutches. Each gear set handles specific speed ranges, replacing the integrated planetary gear mechanism and reducing structural complexity while maintaining multiple speed capabilities
Solution Approach 2:
The externally-meshed gear sets are designed to perform multiple functions: the first and second speed gear sets provide forward speeds, the reverse speed gear set provides reverse speed, and they can be combined to achieve various speed ratios. This multi-functional design eliminates the need for separate planetary gear mechanisms for different speed ranges
2Adaptability or versatility
If a planetary gear set is used in the auxiliary shift apparatus, then two forward speeds and one reverse speed can be realized, but the volume and weight increase leading to deteriorated mountability and fuel economy
Solution Approach 1:
The transmission system is divided into multiple externally-meshed gear sets (first speed gear set, second speed gear set, reverse speed gear set) that operate independently but coordinate through clutches. Each gear set handles specific speed ranges, replacing the integrated planetary gear mechanism and reducing structural complexity while maintaining multiple speed capabilities
Solution Approach 2:
The patent uses simpler, lighter externally-meshed gear sets instead of complex planetary gear mechanisms. These gear sets are designed for straightforward manufacturing and assembly, reducing overall weight while achieving the same functional goals of multiple speed ranges
3Ease of operation
If the variable shift apparatus controls the opening of shift-speed control valve, then the target shift-speed can be achieved, but the speed ratio adjustment range is limited
Solution Approach 1:
The transmission system is divided into multiple externally-meshed gear sets (first speed gear set, second speed gear set, reverse speed gear set) that operate independently but coordinate through clutches. Each gear set handles specific speed ranges, replacing the integrated planetary gear mechanism and reducing structural complexity while maintaining multiple speed capabilities
Solution Approach 2:
The variable shift apparatus dynamically adjusts the effective gear ratio by selectively engaging different gear sets through clutches based on driving conditions. This dynamic reconfiguration allows the system to expand its operational speed ratio range beyond what a single fixed gear set could provide
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 improves mountability, reduces weight and volume, and enhances fuel economy and power performance by allowing continuous speed ratio adjustment within basic shift-speeds, thereby enlarging the range of speed ratios.
Implementation Method 1
The variable shift apparatus is adapted to change the speed ratios continuously by controlling widths of the first and second variable pulleys connected through the metal belt by hydraulic pressure
Implementation Method 2
a first friction element including a plurality of friction plates and a plurality of friction drums alternately stacked, the friction plates being selectively friction-engaged with the friction drums to transmit or release torque
Data Source
AI summary
A continuously variable transmission apparatus for a vehicle, may include a main shaft configured to receive torque of an engine, a subshaft disposed in parallel with and spaced apart from the main shaft, a reverse speed gear set having a reverse speed gear selectively connected to the main shaft, a first speed gear set having a first speed gear selectively connected to the subshaft, a second speed gear set having a second speed gear selectively connected to the subshaft, a variable shift apparatus engaged with the main shaft and the subshaft and continuously changing a ratio between rotation speeds of the main shaft and the subshaft so as to transmit torque of the main shaft to the subshaft, and an output gear set transmitting torque transmitted from the first speed gear or the second speed gear to a differential through a final reduction gear.