V-belt Continuously Variable Transmission Research Articles

Interactive Effect between Organic Friction Modifiers and Additives on Friction at Metal Pushing V-Belt CVT Components

ABSTRACTThe interactions between organic friction modifiers (FMs) and other additives in a continuously variable transmission (CVT) fluid (CVTF) are investigated with the goal of optimizing friction management of metal pushing V-belt CVTs. Three types of FMs (oleic acid, oleyl alcohol, and glycerol mono-oleate [GMO]) were formulated in poly-α-olefin (PAO) and a fully formulated CVTF, and the friction performance was evaluated in a reciprocating test apparatus (TE77). To estimate their effect on the major frictional components in the CVTs, a steel belt–pulley and a torque converter clutch, the tribotests were carried out with both steel–steel and paper–steel sliding configurations. Then, the posttest materials were assessed by surface analysis techniques to observe the chemical nature of any reacted layers at the surface.The results indicate that the friction on the steel surface was significantly influenced by a combination of the FMs and the CVTF additives as well as the functional group of the FMs. Although oleic acid and GMO typically present greater friction reduction than oleyl alcohol under most conditions, oleic acid did not decrease friction at the steel–steel contact with the presence of the other additives in the CVTF formulation; the friction reduction effect was impaired by the presence of other additives. Surface analysis of the posttest specimens implied that it was interactions with the calcium detergent that inactivated the FM effect of oleic acid.

Application of V-Belt Continuously Variable Transmission System Using Hybrid Recurrent Laguerre Orthogonal Polynomials Neural Network Control System and Modified Particle Swarm Optimization

Because the V-belt continuously variable transmission (CVT) system spurred by permanent magnet synchronous motor (PMSM) has unknown nonlinear and time-varying properties, the better control performance design for the linear control design is a time consuming procedure. In order to conquer difficulties for design of the linear controllers, the hybrid recurrent Laguerre orthogonal polynomials neural network (NN) control system, which has online learning ability to react to unknown nonlinear and time-varying characteristics, is developed for controlling PMSM servo-driven V-belt CVT system with the lumped nonlinear load disturbances. The hybrid recurrent Laguerre orthogonal polynomials NN control system consists of an inspector control, a recurrent Laguerre orthogonal polynomials NN control with adaptation law, and a recouped control with estimation law. Moreover, the adaptation law of online parameters in the recurrent Laguerre orthogonal polynomials NN is originated from Lyapunov stability theorem. Additionally, two varied learning rates of the parameters by means of modified particle swarm optimization (PSO) are posed in order to achieve better convergence. At last, comparative studies shown by experimental results are illustrated in order to verify the effectiveness of the proposed control scheme.

Composite recurrent Laguerre orthogonal polynomials neural network dynamic control for continuously variable transmission system using altered particle swarm optimization

The composite recurrent Laguerre orthogonal polynomials neural network (NN) control system using altered particle swarm optimization (PSO) is developed for controlling the V-belt continuously variable transmission (CVT) system driven by permanent magnet synchronous motor to obtain better control performance. The simplified dynamic and kinematic models of a V-belt CVT system are derived by law of conservation. The control system consists of an inspector control, a recurrent Laguerre orthogonal polynomials NN control with adaptation law, and a recouped control with estimation law. Moreover, the adaptation law of online parameters in the recurrent Laguerre orthogonal polynomials NN is originated from Lyapunov stability theorem. Additionally, two optimal learning rates of the parameters by means of altered PSO are posed in order to achieve better convergence. At last, comparative studies shown by experimental results are illustrated to demonstrate the control performance of the proposed control scheme.

Permanent magnet synchronous motor controlled V-belt continuously variable transmission driven electric scooter using hybrid modified recurrent Legendre NN control system

Due to V-belt continuously variable transmission (CVT) driven electric scooter with unknown nonlinear and time- vary characteristics, an accurately dynamic modeling of V-belt CVT driven electric scooter is the time-consuming procedure for the linear controller design. A hybrid modified recurrent Legendre neural network (NN) control system is proposed to control the V-belt CVT driven electric scooter under the occurrence of nonlinear load disturbances with parametric variations in order to acquire good control performance. Firstly, system structure of the V-belt CVT driven electric scooter by using a permanent magnet synchronous motor (PMSM) servo drive system is proposed in this study. Secondly, the hybrid modified recurrent Legendre NN control system, which consists of an inspector control, a modified recurrent Legendre NN control with adaptive law and a recouped control with estimated law, is proposed to control the V-belt CVT driven electric scooter by using PMSM servo drive. Moreover, the on-line parameters tuning methodology of the modified recurrent Legendre NN is derived according to Lyapunov stability theorem and gradient descent method. Furthermore, two optimal learning rates of the parameters in the modified recurrent Legendre NN are developed to speedup convergence. Finally, to show the effectiveness of the proposed control scheme, comparative studies are demonstrated by simulated and experimental results.

PMSM Servo Drive for V-Belt Continuously Variable Transmission System Using Hybrid Recurrent Chebyshev NN Control System

Because the wheel of V-belt continuously variable transmission (CVT) system driven by permanent magnet synchronous motor (PMSM) has much unknown nonlinear and time-varying characteristics, the better control performance design for the linear control design is a time consuming job. In order to overcome difficulties for design of the linear controllers, a hybrid recurrent Chebyshev neural network (NN) control system is proposed to control for a PMSM servo-driven V-belt CVT system under the occurrence of the lumped nonlinear load disturbances. The hybrid recurrent Chebyshev NN control system consists of an inspector control, a recurrent Chebyshev NN control with adaptive law and a recouped control. Moreover, the online parameters tuning methodology of adaptive law in the recurrent Chebyshev NN can be derived according to the Lyapunov stability theorem and the gradient descent method. Furthermore, the optimal learning rate of the parameters based on discrete-type Lyapunov function is derived to achieve fast convergence. The recurrent Chebyshev NN with fast convergence has the online learning ability to respond to the system's nonlinear and time- varying behaviors. Finally, to show the effectiveness of the proposed control scheme, comparative studies are demonstrated by experimental results.

Novel adaptive modified recurrent Legendre neural network control for a PMSM servo-driven electric scooter with V-belt continuously variable transmission system dynamics

Because of the unknown nonlinearity and time-varying characteristics of a V-belt continuously variable transmission (CVT) driven electric scooter system using a permanent magnet synchronous motor (PMSM) servo drive, its accurate dynamic model is difficult to establish for the design of the linear controller in the whole system. In order to conquer this difficulty and increase robustness, a novel adaptive modified recurrent Legendre neural network (NN) control system is proposed for controlling a PMSM servo-driven electric scooter with a V-belt CVT system. The novel adaptive modified recurrent Legendre NN control system consists of a modified recurrent Legendre NN control with adaptation law and a compensated control with estimation law. Additionally, the online parameter tuning methodology of the modified recurrent Legendre NN control and the estimation law of the compensated control can be derived by using the Lyapunov stability theorem. Furthermore, two optimal learning rates of the modified recurrent Legendre NN are proposed according to a discrete-type Lyapunov function in order to raise the speed of convergence. Finally, comparative studies are provided by experimental results in order to show the effectiveness of the proposed control scheme.

A PMSM Driven Electric Scooter System with a V-Belt Continuously Variable Transmission Using a Novel Hybrid Modified Recurrent Legendre Neural Network Control

An electric scooter with a V-belt continuously variable transmission (CVT) driven by a permanent magnet synchronous motor (PMSM) has a lot of nonlinear and time-varying characteristics, and accurate dynamic models are difficult to establish for linear controller designs. A PMSM servo-drive electric scooter controlled by a novel hybrid modified recurrent Legendre neural network (NN) control system is proposed to solve difficulties of linear controllers under the occurrence of nonlinear load disturbances and parameters variations. Firstly, the system structure of a V-belt CVT driven electric scooter using a PMSM servo drive is established. Secondly, the novel hybrid modified recurrent Legendre NN control system, which consists of an inspector control, a modified recurrent Legendre NN control with an adaptation law, and a recouped control with an estimation law, is proposed to improve its performance. Moreover, the on-line parameter tuning method of the modified recurrent Legendre NN is derived according to the Lyapunov stability theorem and the gradient descent method. Furthermore, two optimal learning rates for the modified recurrent Legendre NN are derived to speed up the parameter convergence. Finally, comparative studies are carried out to show the effectiveness of the proposed control scheme through experimental results.

Analytical model for the power losses in rubber V-belt continuously variable transmission (CVT)

In the present work closed form relationships for the power losses in rubber V-belt CVT are obtained, together with expressions for the axial thrust on both the driving and driven pulleys, starting from simple physical hypotheses. Losses have been grouped into three main contributions: frictional sliding losses, longitudinal and lateral material hysteresis and frictional losses due to the engagement/disengagement of the belt at the entrance and exit from the pulleys.In order to keep the model simple and to obtain a closed form solution, circumferential slip is assumed to take place mainly in the driven pulley and the sliding angle is assumed constant along the sliding portion of the contact arc.The model was validated through comparison with experimental results obtained on a dedicated test bench capable of measuring the transmitted torques and the axial thrusts on both pulleys, the pulleys rotating speeds and the total belt tension. The sliding angle γ and the damping coefficient Ψ, which were introduced in the analytical relationships, were determined by a best fit procedure on the basis of the obtained experimental results. After having obtained those parameters, the model appeared to be capable of reproducing with a fairly satisfactory agreement the power losses, as well as the axial loads on the pulleys, which were obtained in different operating conditions; thus it is proposed as a useful tool for the design of this kind of transmission.

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

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.

Transient dynamics of metal V-belt CVT: Effects of band pack slip and friction characteristic

A continuously variable transmission (CVT) offers a continuum of gear ratios between desired limits. The present research reports a detailed continuous one-dimensional transient-dynamic model of a metal V-belt CVT that accurately captures the various transient dynamic interactions occurring in the CVT system. Since a sundry of models mentioned in the literature ignore the influence of slip between the band pack and the belt element on the CVT performance, a unique model is outlined in this paper that aptly captures the slip-dynamics between the band-pack and the belt element. A considerable amount of effort in this paper is also dedicated towards modeling the inertial coupling between the belt and the pulley and studying its influence on the dynamic performance of a CVT. A metal V-belt CVT falls under the category of friction-limited drives as its performance and torque capacity rely significantly on the friction characteristic of the contact patch between the belt element and the pulley. A unique friction characteristic is also embedded into the CVT model to capture the effects of friction under dry and lubricated contact conditions. Simple trigonometric functions are introduced to capture the effects of pulley flexibility on the thrust ratio and slip behavior of the CVT. The results discuss the influence of band pack slip, friction characteristic, and pulley flexibility on the dynamic performance, the axial force requirements, and the torque transmitting capacity of a metal V-belt CVT drive.

Transient Dynamics of the Metal V-Belt CVT: Effects of Pulley Flexibility and Friction Characteristic

A continuously variable transmission (CVT) offers a continuum of gear ratios between desired limits. The present research focuses on developing a continuous one-dimensional model of the metal V-belt CVT in order to understand the influence of pulley flexibility and friction characteristics on its dynamic performance. A metal V-belt CVT falls under the category of friction-limited drives as its performance and torque capacity rely significantly on the friction characteristic of the contact patch between the belt element and the pulley. Since the friction characteristic of the contact patch may vary in accordance with the loading and design configurations, it is important to study the influence of the friction characteristic on the performance of a CVT. Friction between the belt and the pulley sheaves is modeled using different mathematical models which account for varying loading scenarios. Simple trigonometric functions are introduced to capture the effects of pulley deformation on the thrust ratio and slip behavior of the CVT. Moreover, since a number of models mentioned in the literature neglect the inertial coupling between the belt and the pulley, a considerable amount of effort in this paper is dedicated towards modeling the inertial coupling between the belt and the pulley and studying its influence on the dynamic performance of a CVT. The results discuss the influence of friction characteristics and pulley flexibility on the dynamic performance, the axial force requirements, and the torque transmitting capacity of a metal V-belt CVT drive.

Modelling of loss mechanisms in a pushing metal V-belt continuously variable transmission. Part 1: Torque losses due to band friction

The power transmission efficiency of continuously variable transmissions (CVTs) based on the pushing metal belt is acknowledged to be lower than that of discrete ratio alternatives. This tends to negate the potential fuel economy benefits that are obtained by improved engine/load matching with a CVT. This series of three papers details an investigation into the loss mechanisms that occur within the belt drive as a first step to obtaining improvements in efficiency. Experimental work has been undertaken to investigate the no-load and low-load torque losses associated with a pushing metal V-belt CVT. This first paper describes a new analysis of the principal torque losses occurring in the metal belt CVT due to relative motion occurring between the belt segments and bands. The work takes into account new findings in other research and changes in the design of the metal V-belt. The torque loss model proposed in this paper is supported by experimental data from several different test procedures. A number of additional torque loss mechanisms, due to pulley deflections, are described in Part 2 of the series. The findings from this current paper support an analysis of belt-slip losses, which is described in detail in Part 3.

Case Study: Infinitely variable transmissions with automatic regulation

An infinitely variable transmission (IVT) is a continuously variable transmission with an infinite ratio range, which means that the transmission ratio may be zero. IVTs are generally made up of three elements: a continuously variable transmission (CVT), a planetary gear train and a fixed ratio mechanism. Automatically regulated CVTs offer the advantage of automatically changing the transmission ratio without requiring sophisticated control systems. In this work the possibility of realizing an automatically regulated IVT is appraised, i.e. with automatic regulation of the transmission ratio, in relation to operational conditions. The use of the automatically regulated V-belt CVT, endowed with simple devices of axial force, is hypothesized. For the different types of devices the characteristic curves of operation, the power flows and the efficiency of the automatically regulated IVT are determined.

Modeling and Control of a V-Belt CVT

One of the major contributor to overall vehicle energy inefficiency is the finite gearratios which do not pennit an engine to run at its fuel optimal RPM for all forward speeds. A Continuously Variable Transmission (CVT) allows continuous variation of the gear ratio. As a result. a greater overall system efficiency. and reduction in fuel consumption are achieved. In this work. we construct a bond graph model of a V -Belt CVT. This model can be used both to investigate the changes in the overall system efficiency due to reconfiguring a standard transmission into a CVT. and it can be used for development of control strategies. This model. if desired. can be expanded to higher degrees of complexity that includes a prescribed engine model.

An experimental study on transmission efficiency of a rubber V-belt CVT

This paper presents an experimental investigation on the speed and torque loss components of the power loss of a rubber V-belt continuously variable transmission (CVT) as operating conditions (parameters) change. These conditions include the speed ratio, belt tension, rotational speed, external load, diameters of the pulley, etc. A dynamometer is constructed to measure the speeds and torques of the driving and driven pulleys so as to identify the losses and efficiency of the experimental CVT. The power loss of the CVT is investigated not only at constant running speeds but during acceleration when the speed ratio changed continuously. An uncertainty analysis is then performed for the estimation of the accuracy of experimental data. In addition, the repeatability of the experiment was studied to guarantee that reliable results were obtained. Experimental results demonstrated that the power loss as well as transmission efficiency of the CVT differed from those of the V-belt drives.

A Study on Metal Pushing V-Belt Type CVT. Characterization of Power Transmitting States of a CVT using Mean Coefficients of Friction as Parameters and their Application for CVT Design.

In order to characterize the power transmitting state of a continuously variable transmission (CVT) using metal V-belts, mean coefficients of friction between blocks and pulleys, and between the blocks and rings, are introduced. The present approach is primarily based on the classical Euler's equation for conventional V-belts. The existence of idle and active arcs is taken into consideration by adjusting the coefficients of friction, since the power is assumed to be transmitted through all the contact arcs of the belt in this study. The power transmitting mechanisms induced by the estimated mean coefficients of friction are highly consistent with the data measured by the sensors made by blocks. The mean coefficients of friction also have some universal trends with respect to transmitted power, torque ratio, speed ratio and so On. The mean coefficients of friction would be applicable not only for characterizing the power transmitting state, but also for designing a CVT using metal V-belts.

Belt Torque Loss in a Steel V-Belt Continuously Variable Transmission

To achieve the potential advantages to be gained by the use of a high ratio range, continuously variable transmission (CVT) in an automobile it is important that the system has a high efficiency and that any inherent loss mechanisms are fully understood. This paper investigates the belt-related torque loss in a steel V-belt CVT. Measurements show that the loss is dependent on the secondary pulley clamping force and on the belt configuration and these results are presented in the paper. A semi-empirical model is proposed to explain the loss. The agreement between the measured results and the values calculated from the model is shown to be good. It is also shown that when the system is in an overdrive ratio and a high efficiency is particularly important the torque loss is large and the efficiency is severely limited, probably to less than 90 per cent.