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Lubricants
Special Issues
Gear Load-Independent Power Losses
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Gear Load-Independent Power Losses

A special issue of Lubricants (ISSN 2075-4442).

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 14539

Special Issue Editor

Dr. Xiang Zhu

E-Mail Website
Guest Editor
College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
Interests: gear transmission system; lubrication system; CFD; clutch system; deep-seabed mining robot vehicle

Special Issue Information

Dear Colleagues,

Gear systems are currently widely used in all fields of industry. Generally speaking, classic oil sump and splash lubrication are exploited at a low and moderate speed, while oil jet lubrication is for high-speed conditions. The former is related to churning phenomena, and the latter is with windage behavior.

In the last few decades, important research on gear load-independent power losses for various types of gear has been extensive, especially for gear drag power losses (churning power losses, windage power losses, etc.). However, the transition between churning and windage phenomena for an isolated gear or a gear pair is relatively unexplored. Furthermore, no clear criterion is defined and published for suggesting which lubrication method for gears to select and which drag power losses model to use in different speed ranges.

The current Special Issue is aimed at the latest developments concerning gear-load-independent power loss mechanisms (such as churning power losses, windage power losses, pocketing power losses, and impacting power losses) and lubrication technology and the effect of gear working parameters upon their lubrication behavior.

Dr. Xiang Zhu
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Lubricants is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • gear lubrication
  • load-independent power losses
  • transition
  • numerical simulation
  • engineering application

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Published Papers (5 papers)

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Research

15 pages, 9523 KiB  
Article
Experimental Investigation of Oil Transport during Low Load to High Load Transient in Internal Combustion Engines
by Mo Li and Tian Tian
Lubricants 2023, 11(2), 76; https://doi.org/10.3390/lubricants11020076 - 11 Feb 2023
Cited by 1 | Viewed by 1548
Abstract
Reducing the Lubricating Oil Consumption (LOC) has been a critical focus for engine manufacturers. LOC not only depends on engine operating condition but also the history of the operating condition variations. This work seeks to understand the oil transport in the ring pack [...] Read more.
Reducing the Lubricating Oil Consumption (LOC) has been a critical focus for engine manufacturers. LOC not only depends on engine operating condition but also the history of the operating condition variations. This work seeks to understand the oil transport in the ring pack during the low load to high load transient through experimental investigations. An optical engine with 2D Laser Induced Fluorescence (2D-LIF) technique, equipped with a modern low-tension Three-Piece Oil Control Ring (TPOCR), was applied to investigate the oil transport in the ring pack. It was found that, after the engine stayed under the blowby separation line long enough, a sudden increase to high load can result in a huge increase of oil ejection to the liner from the top ring groove in the expansion strokes. The mechanism behind it is that, when the load is increased, the oil accumulated inside the top ring groove during the low load condition is pushed out by the gas flow after the peak cylinder pressure is reached. Different combinations of load, speed, rate of change in load and time duration at low load were tested to examine their influence on this leakage mechanism. An operation with a gradual increase of engine load was found to be able to reduce the amount of oil leaked to the liner by releasing more oil to the second land. These findings can help the effort to reduce the oil emission (OE) generated from Spark Ignited (SI) engines equipped with TPOCR in the real-world transient driving conditions as well as the emission tests. Full article
(This article belongs to the Special Issue Gear Load-Independent Power Losses)
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20 pages, 7090 KiB  
Article
Influence of Nozzle Layouts on the Heat-Flow Coupled Characteristics for Oil-Jet Lubricated Spur Gears
by Duan Yang, He Liu, Jianfeng Zhong, Xiang Zhu and Yu Dai
Lubricants 2023, 11(1), 25; https://doi.org/10.3390/lubricants11010025 - 8 Jan 2023
Cited by 4 | Viewed by 1831
Abstract
Aiming to explore the influence of nozzle layouts on the lubrication and cooling performance of spur gears under oil jet lubrication conditions, this paper introduces a heat-flow coupled analysis method to predict the temperature field of the tooth surface with different nozzle layouts. [...] Read more.
Aiming to explore the influence of nozzle layouts on the lubrication and cooling performance of spur gears under oil jet lubrication conditions, this paper introduces a heat-flow coupled analysis method to predict the temperature field of the tooth surface with different nozzle layouts. Firstly, the friction heat formulas integrating the coefficient of friction and average contact stress are presented for calculating heat generation. We also present the impingement depth model, which considers the nozzle orientation parameters, jet velocity, and gear structure of the given spur gear pair for laying out the nozzle. Then, a heat-flow coupled finite element analysis method is exploited to resemble the jet lubrication process and gain the gear temperature characteristics. Finally, the numerical results of this model compare well with those of the experiments, showing that this heat-flow coupled model provides accurate temperature prediction, indicating that the nozzle layouts determined as a function of the oil jet height, deviation distance, and oil injection angle significantly influence the lubrication and cooling performance. Further, this study also reveals that the lubrication performance in cases where the nozzle approaches the side of the pinion is relatively superior. Full article
(This article belongs to the Special Issue Gear Load-Independent Power Losses)
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17 pages, 6188 KiB  
Article
CFD Investigation on Oil Injection Lubrication of Meshing Spur Gears via Lattice Boltzmann Method
by Xiaozhou Hu, Pengfei Li, Can Quan and Jianing Wang
Lubricants 2022, 10(8), 184; https://doi.org/10.3390/lubricants10080184 - 11 Aug 2022
Cited by 11 | Viewed by 2188
Abstract
The meshless Lattice Boltzmann Method (LBM) is introduced and employed to solve the complex two-phase flow problem of jet lubrication of meshing spur gears. Computational fluid dynamics (CFD) simulations based on LBM are carried out using the model of an oil jet impacting [...] Read more.
The meshless Lattice Boltzmann Method (LBM) is introduced and employed to solve the complex two-phase flow problem of jet lubrication of meshing spur gears. Computational fluid dynamics (CFD) simulations based on LBM are carried out using the model of an oil jet impacting rotating gear presented by available experiments, which reveals how the liquid column is broken throughout the tooth tip cutting off the oil jet. Typical oil flow phenomena obtained by simulations are compared with experiments, demonstrating good qualitative agreement, which validates the feasibility of LBM to simulate the air–oil–structure interaction problems involved in the jet lubrication of spur gears. A three-dimensional (3D) simulation model of a spur gear pair lubricated by an oil jet is established, and simulations with different operating conditions are conducted. The evolution process of the oil jet while injecting into the meshing zone is captured, and the effects of jet velocities, jet heights and jet angles on the lubrication performance are investigated. Full article
(This article belongs to the Special Issue Gear Load-Independent Power Losses)
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15 pages, 5974 KiB  
Article
Performance of a New Aeronautic Oil-Guiding Splash Lubrication System
by Yu Dai, Xi Chen, Duan Yang, Lanjin Xu and Xiang Zhu
Lubricants 2022, 10(6), 130; https://doi.org/10.3390/lubricants10060130 - 18 Jun 2022
Cited by 2 | Viewed by 2498
Abstract
Among ever-increasing demands for low power consumption, low weight, and compact reducer systems, an oil-guiding splash lubrication method integrating the oil-guiding cylinder and pipes is suggested to be more suitable for light helicopters, instead of conventional splash or oil jet lubrication. Aiming at [...] Read more.
Among ever-increasing demands for low power consumption, low weight, and compact reducer systems, an oil-guiding splash lubrication method integrating the oil-guiding cylinder and pipes is suggested to be more suitable for light helicopters, instead of conventional splash or oil jet lubrication. Aiming at improving the lubrication and cooling performance of this special lubrication method, this paper introduces an oil-guiding channel to increase oil quantity reaching the driving gear, bearings, and spline. Firstly, the lubrication and cooling effect of the oil-guiding channel in the main gearbox is investigated at various speeds and oil depths by leveraging with a computational fluid dynamics (CFD) technique. Then, a specialized test bench is set up and utilized for experiments to verify the CFD study. These results show that the numerical results are very satisfactory with the data of experimentation, and the maximum value of relative errors is no more than 15%. What is more, the oil flow rate passing through the monitoring plane with the oil-guiding channel is much greater than that without the channel by about three orders of magnitude. It also suggests that the oil-guiding channel could dramatically increase the lubricating oil in the meshing gear pair, and significantly improve the lubrication and cooling effect. Full article
(This article belongs to the Special Issue Gear Load-Independent Power Losses)
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20 pages, 5358 KiB  
Article
Practical Example of Modification of a Gearbox Lubrication System
by Silvia Maláková and Samuel Sivák
Lubricants 2022, 10(6), 110; https://doi.org/10.3390/lubricants10060110 - 1 Jun 2022
Cited by 2 | Viewed by 5474
Abstract
This paper presents the optimization of the lubrication method of a helical bevel gearbox, which is part of a pickling line. The first gear stage of this gearbox showed frequent failures. The bevel gearing and bearings were damaged. Damage analysis was performed, based [...] Read more.
This paper presents the optimization of the lubrication method of a helical bevel gearbox, which is part of a pickling line. The first gear stage of this gearbox showed frequent failures. The bevel gearing and bearings were damaged. Damage analysis was performed, based on which a change in bevel gearing and bearing lubrication was proposed. In this case, the original transmission was lubricated by dip lubrication. The bevel gear wheel was insufficiently submerged below the lubricating oil level. Due to insufficient lubrication of the bevel gearing, both gear wheels, the bevel pinion, and the bevel wheel were damaged. Central circulating lubrication has been proposed for the bevel gear pair and first gearbox shaft bearings. This paper deals with the design of circulating lubrication components. Changes and modifications to an existing lubrication system are proposed. The layout of the gearbox in question was not originally designed and adapted for the circulating lubrication required. To improve the original lubrication system, it was decided that it should be redesigned with central circulating lubrication, which meant implementing the necessary gearbox casing modifications. Our novel contribution is the proposition of an innovative transmission lubrication system aimed at increasing the service life parameters of the transmission. After the implementation of the proposed modifications to the lubrication method, a period of monitoring the operating characteristics of the gearbox followed. With the modification of the lubrication system of the bevel gear pair, the temperature on the gearing surface was lowered by 39%. The service life of the gearbox increased from the original 1.9 years to at least 5 years. On the basis of the long-term monitoring of changes caused by the adjustment of the lubrication method, we can state that the requirement was met, and the frequent failures of this gearbox were eliminated. Full article
(This article belongs to the Special Issue Gear Load-Independent Power Losses)
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