Efficiency and heat balance calculation of worm gears

Paschold, Constantin; Sedlmair, M.; Lohner, Thomas; Stahl, Karsten

doi:10.1007/s10010-019-00390-1

Cited by 22 publications

(18 citation statements)

References 11 publications

(13 reference statements)

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“…The rolling elements transport heat out of the contact and contribute based on the heat fluxes to the surrounding system to its inner temperature distribution. To describe the heat balance of gearboxes, a thermal network can be established (Paschold et al , 2020). By abstraction of the gearbox system by nodal points, an efficient calculation of heat transfer, dissipation and generation is set up.…”

Section: On the Thermal Insulation Effectmentioning

confidence: 99%

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DLC-coated spur gears – part I: friction reduction

Schwarz

Ebner

Lohner

et al. 2021

ILT

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Purpose This paper aims to address the influence of diamond-like carbon (DLC) coatings on the frictional power loss of spur gears. It shows potentials for friction and bulk temperature reduction in industrial use. From a scientific point of view, the thermal insulation effect on fluid friction is addressed, which lowers viscosity in the gear contact due to increasing contact temperature. Design/methodology/approach Thermal insulation effect is analyzed in detail by means of the heat balance and micro thermal network of thermal elastohydrodynamic lubrication contacts. Preliminary results at a twin-disk test rig are summarized to categorize friction and bulk temperature reduction by DLC coatings. Based on experiments at a gear efficiency test rig, the frictional power losses and bulk temperatures of DLC-coated gears are investigated, whereby load, speed, oil temperature and coatings are varied. Findings Experimental investigations at the gear efficiency test rig showed friction and bulk temperature reduction for all operating conditions of DLC-coated gears compared to uncoated gears. This effect was most pronounced for high load and high speed. A reduction of the mean gear coefficient of friction on average 25% and maximum 55% was found. A maximum reduction of bulk temperature of 15% was observed. Practical implications DLC-coated gears show a high potential for reducing friction and improving load-carrying capacity. However, the industrial implementation is restrained by the limited durability of coatings on gear flanks. Therefore, a further and overall consideration of key durability factors such as substrate material, pretreatment, coating parameters and gear geometry is necessary. Originality/value Thermal insulation effect of DLC coatings was shown by theoretical analyses and experimental investigations at model test rigs. Although trial tests on gears were conducted in literature, this study proves the friction reduction by DLC-coated gears for the first time systematically in terms of various operating conditions and coatings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0257/

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Section: On the Thermal Insulation Effectmentioning

confidence: 99%

“…Micro thermal networks for TEHL contacts may be implemented in thermal network models of gearboxes, such as described in (Paschold et al , 2020). Based on the interaction between the micro thermal network and the surrounding system, a bulk temperature of the rolling elements adjusts.…”

Section: On the Thermal Insulation Effectmentioning

confidence: 99%

DLC-coated spur gears – part I: friction reduction

Schwarz

Ebner

Lohner

et al. 2021

ILT

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“…The wheel bulk temperature can, for example, be calculated with DIN 3996 [2]. As it depends strongly on the heat dissipation properties of the gear box system [27,28], the wheel bulk temperature might also be measured on the actual gear box for better accuracy. The flash temperature is determined with Eq.…”

Section: Derived Formulas For Contact Temperature Calculationmentioning

confidence: 99%

Scuffing load capacity calculation of worm gears

Roth

Hein

Stahl

2021

Forsch Ingenieurwes

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Worm gears with wheels of harder materials, such as cast iron or steel, are often prone to the damage type scuffing, which can cause a sudden and rapid failure of the gear box. Contact temperature is a suitable criterion to determine the scuffing safety for other types of gears. However, for worm gears, a scuffing load capacity calculation is not available at the moment. This paper presents a numerical temperature simulation for worm gears that considers transient multidimensional heat transfer and local frictional loading due to the contact. Based on the results of this simulation, this paper derives a simplified calculation of worm gear contact temperatures. The calculation only contains input parameters that are already part of current standards. Its result, the contact temperature of worm gears, can be used to rate the scuffing load capacity.

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“…In this study, the TNM in WTplus as shown by the authors in [32] is extended to calculate gearbox component temperatures for transient operation conditions.…”

Section: Introductionmentioning

confidence: 99%

Calculating component temperatures in gearboxes for transient operation conditions

Paschold

Sedlmair

Lohner

et al. 2021

Forsch Ingenieurwes

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The knowledge of component temperatures during transient operation conditions is essential for an optimal design of a gearbox. This is because critical peak temperatures limit the transferable power as well as the load capacity. Moreover, understanding the thermal behavior of the gearbox is key to improving its efficiency. Therefore, the Thermal Network Method (TNM) of the calculation program WTplus was extended to calculate component temperatures in gearboxes for transient operation conditions. Specifically, the TNM considers the component masses and specific heat capacities of each node modelling the gearbox structure. This enables the algorithm to compute a corresponding system of differential equations and thus determine the temperature change over time. Therefore, WTplus can be used to identify critical gearbox component temperatures during load cycles. The applied method was validated with measurements collected at the FZG gear efficiency test rig.

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Efficiency and heat balance calculation of worm gears

Cited by 22 publications

References 11 publications

DLC-coated spur gears – part I: friction reduction

DLC-coated spur gears – part I: friction reduction

Scuffing load capacity calculation of worm gears

Calculating component temperatures in gearboxes for transient operation conditions

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