CVT Drive Sheave One-Way Collar for Engine Braking Engagement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional continuously variable transmission (CVT) systems face challenges in implementing a reliable and efficient engine braking system, particularly in vehicles like all-terrain vehicles (ATVs) and utility terrain vehicles (UTVs), as the fixed and movable sheaves are spaced apart during engine braking, limiting the engagement of the belt and requiring a mechanism to effectively clamp down on the belt to provide adequate braking.
Innovation Solution
The introduction of a one-way engagement collar within the drive sheave assembly of a CVT, which includes a central recess in the fixed sheave and a sleeve with ramp members, allowing the collar to rotate freely in one direction and lock in the other, enabling axial movement to engage the belt and provide engine braking, while also disengaging when a threshold is reached to protect vehicle components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional braking system is used to slow down a vehicle on steep terrain, then the vehicle can be decelerated, but the braking system may not be adequate for extreme terrain conditions and may not provide sufficient engine braking effect
Solution Approach 1:
The patent combines the braking function with the CVT drive sheave assembly by integrating a collar that can engage with the belt. This merging of functions allows the transmission system to provide both power delivery and engine braking capabilities, making the system more versatile for different terrain conditions without requiring a separate braking mechanism.
Solution Approach 2:
The collar is designed to dynamically engage and disengage from the belt based on operational conditions. During normal operation, the collar rotates freely with the sleeve. During engine braking conditions, the collar engages with the belt to provide braking effect. This dynamic behavior allows the system to adapt to varying terrain and operational requirements.
2Ease of operation
If the fixed sheave and moveable sheave are spaced away from each other to achieve idle condition, then the belt can rotate freely on the sleeve, but the engine braking system becomes difficult to implement reliably
Solution Approach 1:
The collar acts as an intermediary component between the sleeve and the belt. It is mounted on the sleeve but can engage with the belt when needed. This intermediary structure allows the system to maintain idle conditions with sheaves spaced apart while still enabling reliable engine braking engagement when required.
3Reliability
If an engine braking system is implemented in a CVT, then vehicle control on steep terrain is improved, but the system may cause excessive stress on components if not properly disengaged
Solution Approach 1:
The collar incorporates a spring-loaded mechanism that provides feedback-based engagement and disengagement. The spring force allows the collar to engage with the belt during engine braking conditions while automatically disengaging when the braking force exceeds a certain threshold or when normal operation resumes. This feedback mechanism protects components from excessive stress while maintaining effective vehicle control.
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 solution effectively engages the belt during engine braking, providing torque coupling between the engine and drivetrain, and disengages when necessary to prevent component damage, enhancing the braking performance and reliability of CVT systems in challenging terrain conditions.
Implementation Method 1
The one-way engagement collar is configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction
Implementation Method 2
Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction
Implementation Method 3
The sleeve is rotatably mounted on the post. A mid-portion of the sleeve is positioned between the fixed sheave and the movable sheave and has an outer surface configured to engage an inner surface of a belt
Implementation Method 4
Each ramp member is configured to engage an associated sheave ramp... and move the one-way engagement collar axially to engage a side of the belt
Data Source
AI summary
A drive sheave assembly of a continuously variable transmission is provided. A fixed sheave of the assembly includes a central recess. A plurality of sheave ramps are located within the central recess. A one-way engagement collar is configured to rotate freely on an end portion of a sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction. The one-way engagement collar further has a plurality of ramp pockets. A ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of a belt when the sleeve rotates in the second direction.