Study of the Prediction Method for Maximum Traction Coefficient

Sano, Takeshi; Tomita, Mitsuaki; Inoue, Masashi; Takeuchi, Yasuhiro; Yorinaga, Muneo

doi:10.4271/2013-01-0366

Cited by 8 publications

(2 citation statements)

References 7 publications

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“…where CED and M w in Eqs. (15,16) refer to the cohesive energy density [GPa] and the molecular weight of the oil [g/mol], respectively [17][18][19]. The viscosity index α in Eq.…”

Section: Viscoelastoplastic Modelmentioning

confidence: 99%

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Development of a High-Power Two-Roller Traction Tester and Measurement of Traction Curves

et al. 2016

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Measuring and estimating the traction coefficient is necessary to improve transmitting efficiency and design compact, lightweight toroidal continuously variable transmissions (T-CVTs). However, few attempts have been made to measure and estimate the traction coefficient of T-CVTs under practical usage conditions, and the design of T-CVTs has used extrapolated values from traction coefficients measured under low-power conditions. Therefore, we developed a high-power two-roller traction tester to clarify variation trends in traction curves under operating conditions similar to a T-CVT. The results showed a nearly linear relation between the maximum traction coefficient and the roller surface temperature. Furthermore, the change rate of the maximum traction coefficient with respect to roller surface temperature was dependent on the maximum contact pressure. This paper also compares several traction models under practical operating conditions. A viscoelastoplastic model was constructed and compared with a conventional elastoplastic model. In a wide range of operating conditions, the viscoelastoplastic model showed small differences in the maximum traction coefficient between measured and calculated curves compared with the elastoplastic model. The traction tester and the traction model contribute to building a traction curve database to make T-CVTs more compact, lightweight, and efficient.

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“…where CED and M w in Eqs. (15,16) refer to the cohesive energy density [GPa] and the molecular weight of the oil [g/mol], respectively [17][18][19]. The viscosity index α in Eq.…”

Section: Viscoelastoplastic Modelmentioning

confidence: 99%

“…1 , g 2 : Free parameters determined through curve fitting with measured traction curvesThe viscosity oil η and the Eyring stress τ 0 are expressed as a function of oil film temperature T f and contact pressure P[17]:…”

mentioning

confidence: 99%

Development of a High-Power Two-Roller Traction Tester and Measurement of Traction Curves

et al. 2016

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show abstract

Method for estimating traction curves under practical operating conditions

Itagaki¹,

Ohama²,

Rajan

2020

Tribology International

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Interpretation of temperature and rheological model involved in traction coefficient prediction

Sano

Itoigawa

Inoue

2016

Transactions of the JSME (In Japanese)

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In our previous papers, we attempted to predict traction coefficient by combining oil film rheological models and heat conduction models. The rheological characteristic was considered by dividing rheological region in viscous and plastic. In addition, we formed a very tiny thin film sensor on rolling surface, and challenged to measure temperature change directly when the sensor passed through inside contact portion. But physical interpretation of shear flow transition between two rheological regions was still unclear. Since the plastic model was determined as empirical formula, its universality was also insufficient. In this paper, we define boundary continuity of shear flow transition between the two rheological regions in a new interpretation. Further utilizing this result, we propose a theoretical approach to determine the plastic model by using rheological parameters in viscous region. When the model is derived theoretically and if it could express physical phenomena as a function of actual temperature, we need accurate oil film temperature estimation. In that case, we show that it is effective to make the temperature prediction model in vicinity of contact portion. This is because the time constant of contact film thermal diffusion is small, it makes sense as an effective prediction of traction coefficient. Also by the thin film sensor measurement, the time constant is actually confirmed to be extremely small.

show abstract

Study of the Prediction Method for Maximum Traction Coefficient

Cited by 8 publications

References 7 publications

Development of a High-Power Two-Roller Traction Tester and Measurement of Traction Curves

Development of a High-Power Two-Roller Traction Tester and Measurement of Traction Curves

Method for estimating traction curves under practical operating conditions

Interpretation of temperature and rheological model involved in traction coefficient prediction

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