Development and Assessment of Traction Fluids for Use in Toroidal (IVT) Transmissions

Newall, Jonathan; Nicolson, David M.; Lee, Adrian P.; Evans, Stephen P.

doi:10.4271/2002-01-0588

Cited by 22 publications

(3 citation statements)

References 11 publications

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“…bestimmen. Insbesondere spezielle Reibradöle, sogenannte traction fluids [Mat84,New02] verfestigen sich dabei und ermöglichen eine Trennung der Oberflächen (Spaltweite < 1 m [John77] bei gleichzeitig hoher zulässiger Scherbeanspruchung in der Größenordnung von τ = 100 N/mm 2 . Die Momentenübertragung erfolgt durch Umfangskräfte F t , die zwischen den rotationssymmetrischen Rädern unter der Anpresskraft F n (Abb.…”

Section: Berechnungsgrundlagenunclassified

Konstruktionselemente des Maschinenbaus 2

2012

Springer-Lehrbuch

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Section: Berechnungsgrundlagenunclassified

Konstruktionselemente des Maschinenbaus 2

2012

Springer-Lehrbuch

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“…In gear contacts, mean pressures are typically between 1 and 2 GPa and most research on EHD friction, with one main exception [6], has been made at these pressures. However, there are some machine components, in particular rolling bearings, but also some constant velocity joints [7] and continuously variable transmission components [8] that may operate at significantly higher contact pressures, as indicated in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Measurement of EHD Friction at Very High Contact Pressures

Zhang

Spikes

2020

Tribol Lett

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EHD friction curves have been measured up to very high pressure (p mean = 5 GPa, p max = 7.5 GPa) using a newly developed, rolling-sliding, ball on disc machine, the ETM. Six base fluids have been studied, spanning the API base oil categories Group I to Group V. At high pressures, thermal effects become substantial even at quite modest slide-roll ratios, and these must be considered when analysing friction measurements in terms of the underlying rheological properties of the oils. By comparing measurements from steel/steel and WC/WC ball and disc combinations with very different thermal conductivities, the use of thermal correction to derive isothermal friction curves has been validated. At relatively low pressures (mean pressure = 1 GPa), there are substantial differences between the EHD friction properties of the various API Group base oils, but as pressure is raised these diminish and the EHD friction coefficients of all the Groups approach a similar maximum value at a given temperature. EHD friction continues to be quite strongly temperature dependent even at very high pressure. As pressure is increased, EHD friction curves become progressively steeper, so that friction coefficients at very low slide-roll ratios (1 to 2% SRR) become several times greater at high than at low pressure. This has important practical implications for the efficiency of rolling element bearings at high pressures since these components normally operate in this SRR range. There is no evidence of any of the base oils reaching a limiting shear stress over the whole pressure and temperature range studied. Instead, shear stress continues to increase with log(strain rate) in accord with the Eyring-activated flow model up to very high pressures.

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“…Both CVT systems transmit torque based on mechanical contacts, inducing slip and friction. This requires lubrication and the need for traction fluid to transmit torque between metal parts [3], [4]. The gear ratio is restricted due to geometrical constraints of the design, requiring a clutch or torque converter to achieve standstill [5] and a reverse unit to change rotation direction.…”

Section: Introductionmentioning

confidence: 99%

Efficiency of a CVT-Operated EVT Experimentally Evaluated Against Half-Toroidal and Push-Belt CVTs

Druant

Vansompel

Belie

et al. 2018

IEEE Trans. Ind. Electron.

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This article describes how an electrical variable transmission (EVT) can be used as alternative for mechanical continuously variable transmission (CVT) systems. An EVT is an electromagnetic power split device having two mechanical and two electrical ports. The speed ratio between both mechanical ports (rotors) can be varied in a continuously variable way, so that this machine can be used as electromagnetic alternative for the mechanical pushbelt and half-toroidal CVT. Its operating principle is based on splitting the power into an electromagnetic direct path and an electrical path involving two inverters connected back-to-back. Its potential use as CVT is investigated by comparing experimental data against toroidal and belt CVT data from literature having comparable power ratings. To this end measurements are performed on a prototype 120 kW permanent magnet EVT.

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Development and Assessment of Traction Fluids for Use in Toroidal (IVT) Transmissions

Cited by 22 publications

References 11 publications

Konstruktionselemente des Maschinenbaus 2

Konstruktionselemente des Maschinenbaus 2

Measurement of EHD Friction at Very High Contact Pressures

Efficiency of a CVT-Operated EVT Experimentally Evaluated Against Half-Toroidal and Push-Belt CVTs

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