| 1. |
- Hjelm, Rikard, et al.
(författare)
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A multi-perspective method for gear efficiency and contact analysis
- 2023
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Ingår i: Results in Engineering (RINENG). - : Elsevier BV. - 2590-1230. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Modern gearing applications, in particular electrification, impose new challenges in many different fields of engineering and research. In specific, new demands are imposed on gears, including higher rotational speed, lower noise acceptance, and increased efficiency, as well as increased resistance against pitting and scuffing. To meet these demands, a better understanding of gear contacts is needed. The Eurostars project Effigears proposes a novel multi-perspective methodology for assessment of gear efficiency and contact analysis. The methodology consists of using a novel surface treatment method, Triboconditioning (R), implemented in a streamfinishing process, surface measurements using a scattered light method, experimental testing using the standardized FZG test rig, and contact simulations using a novel thermal elasto-hydrodynamic lubrication tool. It is found, in preliminary tests, that enhanced gear performance may be enhanced due to Triboconditioning (R) surface treat-ment. Findings also include better understanding of how surface characteristics and lubricants affect scuffing and pitting, and the effect of load distribution on gearset behavior.
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| 2. |
- Hjelm, Rikard, et al.
(författare)
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Ultrafine particle emissions from dry clutches : number concentration, size distribution and chemical composition
- 2024
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Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2634-3606. ; 4:1, s. 35-42
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Tidskriftsartikel (refereegranskat)abstract
- Non-exhaust sources, such as brakes, tyres, roads, and clutches, emit a large portion of airborne particles in road transportation, from ultrafine to coarse sizes. While airborne wear particle emissions from brakes and road-tyre contacts have been studied extensively, emissions from clutches have been overlooked. A preliminary study using a novel test rig has indicated that dry clutches also emit airborne wear particles. This paper presents a multi-method for the assessment of ultrafine particles from dry clutches regarding the number concentration, size distribution and chemical composition. The results show that ultrafine particles are emitted both during run-in and at the steady state, featuring a bi-modal size distribution. Elementary analysis shows that the particles consist of several elements, predominately iron, silicon, and sulfur. It can be concluded from this study that ultrafine particles are always generated when the clutch is operated. Clutches in automobiles are shown to produce ultrafine particles, consisting of several metallic elements, which become airborne.
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| 3. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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A Friction, Wear and Emission Tribometer Study of Non-Asbestos Organic Pins Sliding Against AlSiC MMC Discs
- 2018
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Ingår i: Tribology in Industry. - : Faculty of Engineering, University of Kragujevac. - 0354-8996 .- 2217-7965. ; 40:2, s. 274-282
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Tidskriftsartikel (refereegranskat)abstract
- The friction, wear and particle emission from an AlSiC MMC brake disc/non-asbestos organic brake pad system is studied using a pin-on-disc tribometer. The results show that this unconventional AlSiC MMC brake disc system presents friction performance as good as a conventional cast iron brake disc system. During braking, brake pad materials are transferred to the brake disc surface to form a protective third body tribo-layer, resulting in a negative specific wear rate of the brake disc. A higher contact load is likely to make it easier to generate the tribo-layer. The tribo-layer also seems to depend on the disc surface grinding features and the contact temperature during braking. By reusing an AlSiC MMC disc where the tribo-layer is already formed, the airborne emission in terms of mass is about 50% lower and in terms of number about the same as the conventional brake contact pair under a similar braking condition. Further full-scale studies are suggested to determine the validity of the findings.
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| 4. |
- Ma, Jijie, et al.
(författare)
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A Comparison of Airborne Particles Generated from Disk Brake Contacts : Induction Versus Frictional Heating
- 2020
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Ingår i: Tribology letters. - : SPRINGER/PLENUM PUBLISHERS. - 1023-8883 .- 1573-2711. ; 68:1
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Tidskriftsartikel (refereegranskat)abstract
- Volatile emissions of vehicle brakes relate to the high temperature of the brake friction pair. However, as a passive parameter of braking applications, temperature is usually studied together with other parameters such as sliding speed and load. Heating tests that increase the friction pair temperature with an induction heater instead of friction are proposed in this study to imitate the rise in temperature in friction tests. Non-friction airborne particles produced solely by the high temperature in heating tests were studied in comparison with friction tests. The results confirmed the existence of non-friction airborne particles and they can represent about 4.5% of the total airborne particles in friction tests. The high-temperature behaviour as well as the composition of the non-friction airborne particles is also presented.
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| 5. |
- Olofsson, Ulf, 1962-, et al.
(författare)
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Nanoparticle emissions from the transport sector: health and policy impacts - the nPETS concept
- 2023
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Ingår i: 2022 Conference Proceedings Transport Research Arena, TRA Lisbon 2022. - : Elsevier BV. ; 72, s. 248-255
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Konferensbidrag (refereegranskat)abstract
- Road, rail, air, and sea transport generate a major fraction of outdoor ultrafine particles. However, there is no common methodology for comparable sub 100 nm particle emissions measurement. This paper presents the nPETS (grant agreement No 954377) concept to understand and mitigate the effects of emerging non-regulated nanoparticle emissions. This paper presents the concept and selected results. For example, nucleation and condensation mechanisms occur more frequently in the urban background site, leading to new particle formation, while mostly fresh emissions are measured in the traffic site.
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| 6. |
- Tu, Minghui, et al.
(författare)
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A comparison of airborne wear particle emission models based on metro station measurements
- 2019
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Ingår i: Proceedings of 10th International Scientific Conference BALTTRIB 2019. - : Vytautas Magnus University. - 2424-5089. ; , s. 150-157
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Konferensbidrag (refereegranskat)abstract
- The main sources of non-exhaust particles around metro systems are the wear from wheel-rail contact, brake contact and the contact between mechanical parts in electric power systems. In order to predict the PM10 levels on underground metro platforms, the relation among time, train frequency and PM10 level should be investigated. Two types of particle emission models have previously been published to determine the PM10 level on underground train platform; these are the linear model and the conservation model. The aim of this study is to compare the results from the two models with a set of field measurements PM10. In 2016, a set of field measurements are performed on four underground metro platforms in Stockholm. The predicted PM10 values from the two models are compared with the measurement data. The accuracy of the two models is analysed and the behaviours of the two models in high and low train frequency regions are separately discussed.
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| 7. |
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| 8. |
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| 9. |
- Tu, Minghui, et al.
(författare)
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Towards a two-part train traffic emissions factor model for airborne wear particles
- 2019
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Ingår i: Transportation Research Part D. - : Elsevier Ltd. - 1361-9209 .- 1879-2340. ; 67, s. 67-76
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Tidskriftsartikel (refereegranskat)abstract
- In 2017 a new railway tunnel containing two stations opened in Stockholm, Sweden. A series of field measurements were carried out on the platforms in this tunnel before and after it was opened for normal traffic. These measurements were used to investigate the contribution of airborne particle emissions from wear processes to total train emissions. This field data was used to develop a two-part train traffic emission factor model for PM10. The two parts are the accumulative effect term (relating to operating distance such as wheel-rail contact and overhead electric line sliding contact) and a brake effect term (relating to the number of braking operations such as brake disc and brake pad contact). The results show that operating a single trial train at a higher than normal frequency on an otherwise empty platform increases the platform particulate concentration until the concentration reaches a steady value. The model suggests that brake emissions account for about 50% of the total emissions measured in the tunnels.
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| 10. |
- Wahlström, Jens, et al.
(författare)
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A study of the effect of brake pad scorching on tribology and airborne particle emissions
- 2020
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Ingår i: Atmosphere. - 2073-4433. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Non-exhaust wear emissions from disc brakes affect the air quality in cities throughout the world. These emissions come from the wear of the contact surfaces of both the pads and disc. The tribological and emissions performance of disc brakes strongly depend on the contact surface characteristics of the pads and discs. The surfaces of conventional pads are scorched by heating it to several hundred degrees to make the resin carbonize down to a few millimetres deep into the pad. This is done to have a shorter run-in period for new pads. It is not known how scorching will affect the amount of airborne particle emissions. Therefore, the aim of the present study is to investigate how pad scorching influence the airborne particle emissions. This is done by comparing the pin-on-disc tribometer and inertia dyno bench emission results from a Cu-free friction material run against a grey cast iron disc. Three types of modified friction material surfaces have been tested: scorched, extra-scorched and rectified. The results show that the level of scorching strongly affects the airborne particle emissions in the initial phase of the tests. Even if the scorched layer is removed (rectified) before testing, it seems like it still has a measurable influence on the airborne particle emissions. The results from the tribometer tests are qualitatively in line with the inertia dyno bench test for about the first forty brake events; thereafter, the airborne particle emissions are higher for the scorched pads. It can be concluded that it seems that the level of scorching has an adverse influence on both the tribological performance and level of particle emissions.
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