Constant Power Continuously Variable Transmission (CP-CVT): Operating Principle and Analysis

2005 ◽  
Vol 127 (1) ◽  
pp. 114-119 ◽  
Author(s):  
O. S. Cretu ◽  
R. P. Glovnea
Keyword(s):  
Automobile Industry ◽  
Rotation Axis ◽  
Continuously Variable Transmission ◽  
Constant Power ◽  
Traction Drive ◽  
Power Characteristics ◽  
Input And Output ◽  
Output Torque ◽  
Variable Transmission ◽  
Toroidal Traction

The paper is the first of a series of papers that present an original constant power continuously variable transmission (CP-CVT) traction drive. This paper presents the basic functional principle and demonstrates the device’s characteristics of constant power. The device belongs to the well-known toroidal traction drive family. It comprises of two input discs, one conical and the other toroidal, a conical output disc, and a number of spherical balls. The rotation axis of each ball is self-adjusted according to its geometrical position relative to the input and output discs. A variation of the output torque makes the balls change their position relative to the discs and thus causes a change of the transmission ratio. The kinematics and dynamics of the balls are first performed and then the formulas that relate the power transmitted to the kinematics and geometric parameters are deducted. Finally it is concluded that the CP-CVT presented offers good functional steady power characteristics that could fit the automobile industry requirements.

Development of the Sphere-Toroidal Continuously Variable Transmission

2014 ◽  
Vol 986-987 ◽  
pp. 1315-1318
Author(s):  
Shun Min Wang ◽  
Zhuo Li ◽  
Xin Yu Wang ◽  
Xi Chao Li
Keyword(s):  
Continuously Variable Transmission ◽  
Traction Drive ◽  
Input Shaft ◽  
Variable Transmission ◽  
Working Principle ◽  
The Cross ◽  
The Difference ◽  
Toroidal Traction

This paper describes a new genre of Toroidal-CVT system, called the Sphere-Toroidal Continuously Variable Transmission (STCVT), which is derived from the half-toroidal traction drive (TCVT) and introduces its structure and working principle. The torque transfers from the input shaft to the cross-axle universal shaft coupling connected with the driven shaft. By discussing the difference between the torque-transfer, the paper will show the possibility of the application in the vehicle. To conclude, the system has the potential to implement infinite extension for the CVT theoretically.

Causes of Slip in a Continuously Variable Transmission

2003 ◽  
Author(s):  
Songho Kim ◽  
Michael Peshkin ◽  
J. Edward Colgate
Keyword(s):  
Empirical Data ◽  
Velocity Ratio ◽  
Continuously Variable Transmission ◽  
Lateral Loads ◽  
Measured Velocity ◽  
Traction Drive ◽  
The Face ◽  
Variable Transmission ◽  
Computer Controlled ◽  
The Ideal

Rotational CVTs (continuously varible transmissions) constrain the velocities of two rotational joints to a computer-controlled ratio. CVTs traction drive mechanisms that rely on the support of traction forces across rolling contracts. When called upon to transmit loads, CVTs produce a velocity ratio that departs from the ideal transmission ratio. This paper reports on the results of our analysis in pursuit of understanding the mechanics of the rotational CVT. We present the measured velocity ratios in the face of lateral loads at various transmission settings. In addition, wer present our model that closely fits the empirical data.

Double-Cage Constant Power Continuously Variable Transmission (CP-CVT)

2006 ◽  
Author(s):  
Romeo P. Glovnea ◽  
Ovidiu S. Cretu
Keyword(s):  
Continuously Variable Transmission ◽  
Maximum Power ◽  
Transmission Ratio ◽  
Kinematics And Dynamics ◽  
Constant Power ◽  
Active Elements ◽  
Internal Geometry ◽  
Variable Transmission ◽  
Specific Geometry ◽  
New Generation

The paper focuses on the internal construction of an original Constant Power Continuously Variable Transmission (CP-CVT). In a recent publication the authors have introduced the fundamentals of the kinematics and dynamics of the CP-CVT. The present study focuses on the optimisation of the CP-CVT’s internal geometry and the size of its active elements in order to obtain maximum power transmitted with least variation over a range of transmission ratio. The paper concludes that for a specific geometry the CP-CVT presented offers promising characteristics that recommend it as a good candidate in the race of developing a new generation of the automobiles’ powertrain.

Switch-Mode Continuously Variable Transmission With Flywheel Energy Storage

2008 ◽  
Author(s):  
Tyler D. Forbes ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Continuously Variable Transmission ◽  
Drive Train ◽  
Mechanical Transmission ◽  
Ground Vehicles ◽  
Power Sources ◽  
Output Torque ◽  
Switch Mode ◽  
Variable Transmission ◽  
Energy And Power Density

A hybrid drive train significantly improves energy efficiency of ground vehicles. While numerous auxiliary hybrid power sources have been researched, few are capable of the energy and power density of a flywheel coupled with a continuously variable mechanical transmission. The primary challenge of a flywheel hybrid system is a transmission capable of coupling a high speed flywheel to the drive train of the vehicle. A novel solution to this challenge is a switch-mode continuously variable transmission that utilizes a rapidly switching clutch to transmit power. This system, the mechanical analog of a DC-DC boost converter circuit, utilizes a flywheel, a high frequency clutch, an anti-reversing ratchet, and a spring to vary the output torque. The switch-mode continuously variable transmission is demonstrated through an idealized finite difference model, created from the dynamic system of equations. The model is used to demonstrate the system behavior in a passenger car subjected to road loads in various conditions. The output of the model demonstrates pulses in the output torque as a result of the rapidly switching clutch. This output ripple in is smoothed to an acceptable level by the torsion spring. From this preliminary analysis the on-off continuously variable transmission offers an efficient, energy dense, and power dense hybrid vehicle drive train alternative.

Design and Analysis of a Spherical Continuously Variable Transmission

2000 ◽  
Vol 124 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Jungyun Kim ◽  
F. C. Park ◽  
Yeongil Park ◽  
Mishima Shizuo
Keyword(s):  
Energy Efficiency ◽  
Mobile Robots ◽  
Contact Point ◽  
Power Source ◽  
Continuously Variable Transmission ◽  
Small Scale ◽  
Simple Design ◽  
Axis Of Rotation ◽  
Input And Output ◽  
Variable Transmission

In this article we propose the design of a novel continuously variable transmission, the spherical continuously variable transmission (S-CVT). The S-CVT consists of a sphere, input and output discs, and variators. The rotating input and output discs are connected to the power source and output shafts, respectively, while the sphere is situated between the input and output discs. The transmission ratio is controlled by adjusting the location of the contact point between the variators and the sphere, which in turn controls the axis of rotation of the sphere. The S-CVT can smoothly transit between the forward, neutral, and reverse states without any brakes or clutches, and its compact and simple design and its relatively simple control make it particularly effective for mechanical systems in which excessively large torques are not required (e.g., mobile robots, household appliances, small-scale machining centers). We describe the operating principles behind the S-CVT, including a kinematic and dynamic analysis. Simulations and experiments with a constructed prototype are conducted to assess the performance of the S-CVT, including a study of its energy efficiency vis-a´-vis reduction gears.

Influence of Flyweight Profile on Regulating Characteristic of Rubber V-Belt CVT

2011 ◽  
Vol 86 ◽  
pp. 210-213
Author(s):  
Hua Feng Ding ◽  
Cai Chao Zhu ◽  
Huai Ju Liu
Keyword(s):  
Steady State ◽  
Numerical Model ◽  
Engine Speed ◽  
Continuously Variable Transmission ◽  
Constant Power ◽  
Constant Radius ◽  
Power Peak ◽  
Variable Transmission

Flyweight is an important part of CVT (continuously variable transmission), whose quality affects the regulating characteristics directly. This paper investigates the influence of flyweight profile on regulating characteristics, which based on the numerical model of the rubber V-belt CVT in steady state. Ideal profile of the flyweight is described which can lead to a constant power peak engine speed. In view of manufacture, the profile is simplified to be an arc and two arcs, respectively, to view the variation of the regulating line of the CVT. Conclusion can be proposed that multi-arcs, like two arcs is better compared with the profile made up of only one constant radius arc according to the subsequence regulating characteristic of CVT.

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