V-belt CVT Sensor Positioning for Usability
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Solution Overview
Problem
Existing V-belt continuously variable transmissions (CVTs) in all-terrain vehicles (ATVs) face challenges in achieving responsive speed change operations due to delayed response to road conditions and difficulties in compactly integrating electric motors and rotational speed sensors, which affect the vehicle's usability and performance.
Innovation Solution
A compact V-belt CVT design featuring an electric motor and control device that adjusts sheave groove widths, with the rotational speed sensor positioned on the primary sheave shaft's end, away from the engine cylinder block, allowing for responsive speed changes without compromising the vehicle's compactness or rider usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotational speed sensor is positioned on the outer side of the vehicle body to enable responsive speed control, then the response speed is improved, but the sensor projects greatly to the outer side and prevents the rider from putting his/her foot in place
Solution Approach 1:
The rotational speed sensor is repositioned from the outer side of the vehicle body to the inner side, specifically on the crankcase or transmission case. This spatial relocation in a different dimension (from external to internal positioning) maintains the sensor's functionality for responsive speed detection while eliminating the interference with the rider's foot placement on the footrest
2Measurement precision
If the rotational speed sensor is positioned around the outer periphery of the primary sheave or secondary sheave for accurate detection, then the measurement accuracy is improved, but the transmission casing is increased in size
Solution Approach 1:
The rotational speed sensor is extracted from its traditional position around the outer periphery of the sheaves and relocated to the inner side of the transmission system, specifically on the crankcase or transmission case. This extraction allows accurate rotational speed detection to be achieved through alternative positioning, thereby maintaining measurement precision while avoiding the need to increase the transmission casing size
3Device complexity
If the rotational speed sensor is installed near heat producing parts for compact arrangement, then the device compactness is improved, but the service life of the sensor is reduced
Solution Approach 1:
The rotational speed sensor is positioned on the inner side of the transmission system where thermal conditions are more favorable. Specifically, it is mounted on the crankcase or transmission case in locations that are thermally favorable, away from direct exposure to high-temperature zones. This localized positioning strategy maintains device compactness while ensuring the sensor operates in a cooler environment, thereby extending its service life
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
The solution enables a highly responsive speed change operation that is sensitive to vehicle running conditions while maintaining a compact and durable CVT configuration, ensuring the rider's footrest space is not obstructed and the sensor is protected from heat sources.
Implementation Method 1
an electric motor; a control device for controlling the electric motor
Implementation Method 2
an endless V-belt received in the respective V-grooves of the primary sheave and the secondary sheave to transmit a rotational driving force between both the sheaves
Implementation Method 3
A previous type of sheave drive mechanism, in general, was the so-called centrifugal type which utilized centrifugal force produced according to the engine speed to displace a movable sheave half in the axial direction
Data Source
AI summary
A V-belt continuously variable transmission (CVT) for a straddle-type vehicle includes a measurement plate for a rotational speed sensor for detecting a rotational speed of a primary sheave shaft to control a speed change ratio. The measurement plate is disposed on an opposite end of the primary sheave shaft, to one end of which a driving force of an engine is input, with respect to a primary sheave.