CVT Tuning Pocket for Acceleration Deceleration Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing CVT systems in golf cars and utility vehicles face challenges in controlling torque transfer ratios during acceleration and deceleration due to the design of helix ramp slots, which generate undesired resistance, impeding smooth acceleration and effective engine braking.
Innovation Solution
A continuously variable transmission (CVT) system with a driven pulley movable sheave featuring a beveled face disk, an elongated hollow cylindrical collar, and a triangular shaped tuning pocket, allowing for controlled axial movement through a roller pin, with distinct angles for acceleration and deceleration sides to manage torque transfer ratios independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If parallel sided helix ramp slots are used in the driven pulley movable sheave, then acceleration control is improved, but deceleration performance deteriorates due to undesired resistance
Solution Approach 1:
The helix ramp slot is segmented into two distinct sections: an acceleration section with a first angle for controlled acceleration, and a deceleration section with a second angle (opposite sign) for efficient deceleration. This segmentation allows each section to be optimized for its specific function, resolving the contradiction between acceleration control and deceleration performance.
Solution Approach 2:
Different sections of the helix ramp slot are given different local properties through varying the angle of the ramp surfaces. The acceleration section has a positive angle to control outward movement, while the deceleration section has a negative angle to facilitate inward movement. This local differentiation eliminates the harmful resistance during deceleration while maintaining acceleration control.
2Ease of manufacture
If the driven pulley movable sheave is designed with a single angle helix ramp slot, then manufacturing is simplified, but independent control of acceleration and deceleration is lost
Solution Approach 1:
The single helix ramp slot is divided into two functional segments with different angles. The acceleration segment and deceleration segment are clearly defined, allowing independent optimization of each phase while maintaining a unified structural approach that remains manufacturable.
Solution Approach 2:
The helix ramp slot transitions from a static single-angle design to a dynamic multi-angle design where the ramp angle changes along the axial direction. This dynamic geometry enables the structure to adapt to different operational phases (acceleration vs. deceleration) while remaining a single integrated component.
3Ease of operation
If the helix ramp slot resists axial outward movement during acceleration, then torque transfer ratio control is improved, but engine braking capability is impeded during deceleration
Solution Approach 1:
The design inverts the approach by using opposite angles for the two sections: a positive angle for the acceleration section to resist outward movement and control torque transfer, and a negative angle for the deceleration section to facilitate inward movement and maximize engine braking. This inversion resolves the contradiction by allowing each phase to have optimized resistance characteristics.
Solution Approach 2:
The ramp angle parameter is changed between sections: from a positive angle during acceleration to a negative angle during deceleration. This parameter change allows the system to provide resistance when needed (acceleration) and reduce resistance when beneficial (deceleration), thereby improving both torque control and engine braking capability.
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 design enables smoother and more controlled acceleration and enhanced engine braking by optimizing torque transfer ratios during both phases, improving vehicle performance and operational efficiency.
Implementation Method 1
the force between the roller pin and the helix ramp slot, both resisting movement of the driven pulley movable sheave axially outward
Implementation Method 2
the axial force inward applied by a driven pulley spring, and the force between the roller pin and the helix ramp slot, both resisting movement of the driven pulley movable sheave axially outward
Implementation Method 3
as the engine output shaft rotational speed increases the driving pulley movable sheave moves axially along the shaft toward the driving pulley fixed sheave, thereby forcing the pulley belt radially outward
Data Source
AI summary
A continuously variable transmission driven pulley movable sheave comprising a beveled face disk, an elongated hollow cylindrical collar extending orthogonally from a center of the beveled face disk, and a triangular shaped tuning pocket disposed in the collar. The tuning pocket is structured and operable to control axial movement of the movable sheave on the elongated neck of the driven pulley. The tuning pocket comprises a first gear side, an acceleration side disposed at a positive angle relative to a reference point on the first gear side, and a deceleration side disposed at a negative angle relative to the reference point on the first gear side.