CVT Drive Pulley Slider Assembly to Prevent Sheave Backlash
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Solution Overview
Problem
Conventional drive pulleys in continuously variable transmissions for snowmobiles experience relative rotation between the spider and movable sheave due to manufacturing tolerances, leading to wear and reduced power transfer efficiency.
Innovation Solution
The implementation of a drive pulley design featuring a fixed sheave, a movable sheave, a spider, and slider assemblies that minimize relative rotation between the spider and movable sheave, utilizing centrifugal actuators and slider blocks with angled surfaces to transfer torque and prevent backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional drive pulley design with pin-connected adjusting arms is used, then the结构简单 (structure is simple), but relative rotation between spider and movable sheave causes wear and reduces power transfer efficiency
Solution Approach 1:
The patent introduces a slider block as an intermediary component between the adjusting arm and the movable sheave. This slider block eliminates relative rotation between the spider and movable sheave by providing a constrained sliding interface, thereby preventing wear and maintaining power transfer efficiency while preserving the overall simplicity of the centrifugal actuator structure.
2Ease of manufacture
If pin connection is used between adjusting arm and movable sheave, then the manufacturing is easy, but backlash occurs during acceleration and deceleration
Solution Approach 1:
The slider block serves as a mediator that replaces the direct pin connection between the adjusting arm and movable sheave. It maintains ease of manufacture through simple sliding interfaces while eliminating backlash by constraining relative rotation, thus achieving both manufacturing simplicity and rotational precision.
3Adaptability or versatility
If adjusting arms pivot outwards during acceleration, then the drive ratio varies progressively, but the arms rub against rollers causing wear
Solution Approach 1:
The slider block acts as an intermediary that separates the pivoting motion of the adjusting arm from the rotational motion of the movable sheave. This allows the drive ratio to vary progressively through arm pivoting while preventing direct rubbing contact between the arms and rollers, thereby extending component service life.
4Reliability
If worn surfaces of rollers make contact with arms, then the roller stops rolling, but this exacerbates rubbing and wear
Solution Approach 1:
The slider block serves as a protective intermediary that prevents direct contact between the adjusting arms and roller surfaces. By eliminating this contact interface, the patent prevents the harmful cycle of wear-induced rubbing and maintains reliable power transfer without generating harmful friction and wear.
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 reduces wear and enhances power transfer efficiency by eliminating or minimizing relative rotation between the spider and movable sheave, thereby improving the performance of the continuously variable transmission.
Implementation Method 1
Each of the arms is connected to the movable sheave of the drive pulley by a pin, and pivots outwards about its corresponding pin. As they pivot, the arms are in contact with corresponding rollers disposed on a spider fixed relative to the fixed sheave. When the adjusting arms pivot outwards as a result of centrifugal force, they slide against their corresponding roller and the axially movable sheave is pushed towards the fixed sheave.
Implementation Method 2
The movable sheave is movable axially toward the fixed sheave by the action of the centrifugal actuators and away from the fixed sheave by a biasing spring.
Data Source
AI summary
A drive pulley for a CVT has a fixed sheave, a movable sheave, a spider, a biasing member biasing the movable sheave axially away from the fixed sheave, at least one centrifugal actuator and at least one slider assembly. The at least one slider assembly has a slider block connected to one of the movable sheave and the spider and abutting another one of the movable sheave and the spider. The slider block slides along the other one of the movable sheave and the spider as the movable sheave moves axially. The at least one slider assembly transfers torque between the movable sheave and the spider. A slider block for a drive pulley of a CVT is also described.