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Mäki, Rikard
Publications (10 of 18) Show all publications
Lund, M., Lundin, J. & Mäki, R. (2009). Determining power and energy limits of friction systems for automatic transmissions: test equipment and methods (ed.). In: (Ed.), (Ed.), Proceedings of the World Tribology Congress 2009: Sunday 6th to Friday 11th, September, 2009, Kyoto, Japan. Paper presented at World tribology congress : 06/09/2009 - 11/09/2009 (pp. 862-862). Tokyo: Japan Society of Tribologists
Open this publication in new window or tab >>Determining power and energy limits of friction systems for automatic transmissions: test equipment and methods
2009 (English)In: Proceedings of the World Tribology Congress 2009: Sunday 6th to Friday 11th, September, 2009, Kyoto, Japan, Tokyo: Japan Society of Tribologists , 2009, p. 862-862Conference paper, Meeting abstract (Other academic)
Abstract [en]

When designing automatic transmissions the performance of friction elements such as wet clutches and wet brakes is vital to the performance and durability of the transmission. In order to achieve high performing friction systems, correct selection of friction lining and transmission fluid is required. This is combined with the need for correct mechanical design with respect to torque capacity and power/energy capacity. In the later stages of development, the friction system performance can be tuned by means of the clutch control system. This is due to the control strategy together with vehicle inertia and rotating inertias in the powertrain influencing the power and energy introduced in the clutches. In order to develop the correct mechanical design and set correct levels of freedom for the clutch control optimization, the designers need to know how much the friction system can be stressed before the transmission durability begins to be influenced in a harmful way.This paper presents methods used to determine the energy and power limits of the friction systems. Data are presented from two different test stands: One similar to an SAE #2 test stand. The latter is a novel test equipment designed to monitor clutch wear and friction under different conditions in order to find the limits of energy and power at which the friction lining durability is affected in a negative way. The test stand is built at Luleå University of Technology. Several genuine Volvo parts are used while other parts are acquired or manufactured. Several design aspects were taken into consideration. Among them was easy access for assembly/disassembly of the clutch. A list of specification requirements was put together and the test stand was designed to meet these. A list of performance attributes:- The total inertia of the system is 0.63 kgm2- The system can be braked in less than 0.5 s- The system is accelerated in less than 10 s- The wear of the clutch is measured- The temperature is measured inside the clutch- The torque transmitted by the clutch is measured- The rotation speed of the system is measured- The pressure activating the clutch is measured- The pressure is controlled with high accuracy by a fast servo solenoid valveThe inertia of the system, the rotation speed and the braking time can be changed such that different power/energy levels can be achieved. The new test stand is described in detail showing the design considerations taken to make the methods reliable.

Place, publisher, year, edition, pages
Tokyo: Japan Society of Tribologists, 2009
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-30117 (URN)3d7637b0-a755-11de-8293-000ea68e967b (Local ID)978-4-9900139-9-8 (ISBN)3d7637b0-a755-11de-8293-000ea68e967b (Archive number)3d7637b0-a755-11de-8293-000ea68e967b (OAI)
Conference
World tribology congress : 06/09/2009 - 11/09/2009
Note
Godkänd; 2009; 20090922 (maalun)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-01-14Bibliographically approved
Marklund, P., Mäki, R., Larsson, R., Höglund, E., Khonsari, M. & Jang, J. (2007). Thermal influence on torque transfer of wet clutches in limited slip differential applications (ed.). Paper presented at . Tribology International, 40(5), 876-884
Open this publication in new window or tab >>Thermal influence on torque transfer of wet clutches in limited slip differential applications
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2007 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 5, p. 876-884Article in journal (Refereed) Published
Abstract [en]

Wet clutches operating under low velocity and high load are studied with the aim of obtaining reliable models for the torque transfer during boundary lubrication conditions. A friction model which takes temperature, speed and nominal pressure into account is developed and used with temperature calculations to be able to simulate behavior of a wet clutch working in boundary lubrication regime. Predicted torque and temperatures from the model agree well with experimental data.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-6567 (URN)10.1016/j.triboint.2006.09.004 (DOI)000244215000019 ()2-s2.0-33845342845 (Scopus ID)4cec6920-8d55-11db-8975-000ea68e967b (Local ID)4cec6920-8d55-11db-8975-000ea68e967b (Archive number)4cec6920-8d55-11db-8975-000ea68e967b (OAI)
Note
Validerad; 2007; 20061216 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mäki, R., Ganemi, B., Höglund, E. & Olsson, R. (2007). Wet clutch transmission fluid for AWD differentials: influence of lubricant additives on friction characteristics (ed.). Paper presented at . Lubrication Science, 19(2), 87-99
Open this publication in new window or tab >>Wet clutch transmission fluid for AWD differentials: influence of lubricant additives on friction characteristics
2007 (English)In: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 19, no 2, p. 87-99Article in journal (Refereed) Published
Abstract [en]

In recent years, several electronically controllable automotive transmission systems using wet clutches as intelligent differentials have emerged on the market. These applications place great demands on the anti-shudder properties of the transmission fluids used. The aims of this study were (i) to investigate the influence of different additives on the friction characteristics of a transmission fluid for all-wheel drive systems featuring wet multi-plate clutch with a sintered brass-based friction material and, based on this knowledge, (ii) to formulate a new transmission fluid with the desired frictional properties. In addition to excellent anti-shudder properties, the new fluid was required to lubricate hypoid gears under high load. To meet this requirement, it is necessary to add significant amounts of extreme pressure additives to the base oil, which are known to have an unfavourable influence on anti-shudder properties, necessitating the adoption of novel additive technologies. The additives studied include anti-wear additives, friction modifiers, corrosion inhibitors, detergents, antioxidants and extreme pressure additives. This paper shows how different additives affect friction in different ways, and that the interactions between the different additives are important to consider. It was concluded that it is feasible to combine good anti-shudder properties for wet clutches with good lubrication of hypoid gears.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-2704 (URN)10.1002/ls.33 (DOI)2-s2.0-34247632706 (Scopus ID)0618d590-40fc-11dd-8634-000ea68e967b (Local ID)0618d590-40fc-11dd-8634-000ea68e967b (Archive number)0618d590-40fc-11dd-8634-000ea68e967b (OAI)
Note
Validerad; 2007; 20080623 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mäki, R., Nyman, P., Ganemi, B. & Olsson, R. (2006). Influence of surface topography and composition of sintered friction material on friction characteristics in wet clutch applications (ed.). In: (Ed.), Proceedings of the 11th Nordic Symposium on Tribology: NORDTRIB 2004 : Tromsø, Harstad, Hurtigruten, [Bodø], Norway, June [1 - 5], 2004. Paper presented at Nordic Symposium on Tribology : 01/06/2004 - 05/06/2004.
Open this publication in new window or tab >>Influence of surface topography and composition of sintered friction material on friction characteristics in wet clutch applications
2006 (English)In: Proceedings of the 11th Nordic Symposium on Tribology: NORDTRIB 2004 : Tromsø, Harstad, Hurtigruten, [Bodø], Norway, June [1 - 5], 2004, 2006Conference paper, Published paper (Refereed)
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-30415 (URN)4355e690-24b0-11dd-9e62-000ea68e967b (Local ID)4355e690-24b0-11dd-9e62-000ea68e967b (Archive number)4355e690-24b0-11dd-9e62-000ea68e967b (OAI)
Conference
Nordic Symposium on Tribology : 01/06/2004 - 05/06/2004
Note

Godkänd; 2004; 20080518 (cira)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-02-26Bibliographically approved
Nyman, P., Mäki, R., Olsson, R. & Ganemi, B. (2006). Influence of surface topography on friction characteristics in wet clutch applications (ed.). Wear, 261(1), 46-52
Open this publication in new window or tab >>Influence of surface topography on friction characteristics in wet clutch applications
2006 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 261, no 1, p. 46-52Article in journal (Refereed) Published
Abstract [en]

In heavily loaded wet clutches, such as in limited slip differentials, sintered friction materials are sometimes used due to their resilience at high loads and high temperatures as well as their competitive cost in comparison to alternative friction materials. During the lifetime of the clutch, changes in the friction materials' topography occur. These changes will influence the friction characteristics of the clutch, and therefore affect the anti-shudder performance of the transmission system. This paper investigates the influence of, and classifies, changes in the topography of the sintered friction material. The topography is measured by utilizing vertical scanning interferometry. Different parameters are investigated in order to find relevant parameters correlating to the wear of the material. Results show that changes in the topography of the friction material do indeed influence the friction characteristics of the clutch and that it is possible to calculate relevant topography parameters that describe the amount of wear the material has been subjected to.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-13601 (URN)10.1016/j.wear.2005.09.020 (DOI)000238856200008 ()2-s2.0-33745179483 (Scopus ID)cd65d520-038c-11dc-8b31-000ea68e967b (Local ID)cd65d520-038c-11dc-8b31-000ea68e967b (Archive number)cd65d520-038c-11dc-8b31-000ea68e967b (OAI)
Note

Validerad; 2006; 20070516 (cira)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mäki, R., Nyman, P., Olsson, R. & Ganemi, B. (2006). Sintered friction material for wet clutch applications: Investigation and classification of wear and its influence on friction characteristics (ed.). In: (Ed.), Proceedings of the 11th Nordic symposium on tribology: NORDTRIB 2004 : Tromsø, Harstad, Hurtigruten, [Bodø], Norway, June [1 - 5], 2004. Paper presented at Nordic Symposium on Tribology : 01/06/2004 - 05/06/2004.
Open this publication in new window or tab >>Sintered friction material for wet clutch applications: Investigation and classification of wear and its influence on friction characteristics
2006 (English)In: Proceedings of the 11th Nordic symposium on tribology: NORDTRIB 2004 : Tromsø, Harstad, Hurtigruten, [Bodø], Norway, June [1 - 5], 2004, 2006Conference paper, Published paper (Refereed)
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-40665 (URN)fe02edc0-65d0-11dc-8a3f-000ea68e967b (Local ID)fe02edc0-65d0-11dc-8a3f-000ea68e967b (Archive number)fe02edc0-65d0-11dc-8a3f-000ea68e967b (OAI)
Conference
Nordic Symposium on Tribology : 01/06/2004 - 05/06/2004
Note

Godkänd; 2004; 20070918 (ysko)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-02-26Bibliographically approved
Mäki, R., Ganemi, B. & Olsson, R. (2006). Wet clutch transmission fluid for AWD differentials: base fluid influence on friction characteristics (ed.). TriboTest Journal, 12(1), 47-56
Open this publication in new window or tab >>Wet clutch transmission fluid for AWD differentials: base fluid influence on friction characteristics
2006 (English)In: TriboTest Journal, ISSN 1354-4063, Vol. 12, no 1, p. 47-56Article in journal (Refereed) Published
Abstract [en]

During the past few years several electronically controllable automotive transmission systems, where wet clutches are used as intelligent differentials, have emerged in the market. In this type of application the anti-shudder properties of the lubricants are of vital importance. This paper investigates the influence of base fluids on the anti-shudder properties of transmission fluids for wet clutches in all-wheel-drive systems. The investigated all-wheel-drive system featuring a wet multi-plate clutch with a sintered brass-based friction material is described. The test equipment used to determine the frictional characteristics of the transmission fluid is described. The parameters studied include base fluid type and base fluid viscosity. It is shown that the choice of base fluid has no impact on torque capacity, but that the base fluid influences the temperature dependence of the dynamic friction and the anti-shudder properties. It is also shown that the major effect on the friction characteristics is caused by additive effects rather than base fluid effects.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-6062 (URN)10.1002/tt.4 (DOI)443dd540-038c-11dc-8b31-000ea68e967b (Local ID)443dd540-038c-11dc-8b31-000ea68e967b (Archive number)443dd540-038c-11dc-8b31-000ea68e967b (OAI)
Note

Godkänd; 2006; 20070516 (cira)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2020-05-05Bibliographically approved
Mäki, R., Ganemi, B., Flores, R. & Olsson, R. (2006). Wet clutch transmission fluid for AWD differentials: influence of lubricant additives on friction characteristics (ed.). In: (Ed.), Wilfried J. Bartz (Ed.), Automotive and industrial lubrication: 15th International Colloquium Tribology, January 17 - 19, 2006 ; [book of synopses 2006]. Paper presented at International Colloquium Tribology : 17/01/2006 - 19/01/2006 (pp. 35). Ostfildern: Techn. Akad. Esslingen
Open this publication in new window or tab >>Wet clutch transmission fluid for AWD differentials: influence of lubricant additives on friction characteristics
2006 (English)In: Automotive and industrial lubrication: 15th International Colloquium Tribology, January 17 - 19, 2006 ; [book of synopses 2006] / [ed] Wilfried J. Bartz, Ostfildern: Techn. Akad. Esslingen , 2006, p. 35-Conference paper, Published paper (Refereed)
Abstract [en]

A study on the influence of base oils on friction properties was carried out. The effects of additive interactions must be considered but were hard to predict. This was most notable with EP additives that were hard to combine with other additives without compromising the anti-shudder properties of the clutch. The developed fluid showed that it is feasible to combine anti-shudder properties and hypoid gear lubrication abilities in one fluid. Good anti-shudder properties were realized despite high concentrations of EP additives. This is an abstract of a paper presented at the 15th International Colloquium Tribology-Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).

Place, publisher, year, edition, pages
Ostfildern: Techn. Akad. Esslingen, 2006
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-37163 (URN)b179e910-aa95-11df-a707-000ea68e967b (Local ID)3-924813-62-0 (ISBN)b179e910-aa95-11df-a707-000ea68e967b (Archive number)b179e910-aa95-11df-a707-000ea68e967b (OAI)
Conference
International Colloquium Tribology : 17/01/2006 - 19/01/2006
Note

Godkänd; 2006; 20100818 (andbra)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-02-26Bibliographically approved
Mäki, R., Nyman, P., Ganemi, B. & Olsson, R. (2005). Measurement and characterisation of anti-shudder properties in wet clutch applications (ed.). In: (Ed.), (Ed.), 2005 SAE world congress: Detroit, Michigan, April 11 - 14, 2005. Paper presented at SAE World Congress : 11/04/2005 - 14/04/2005. Warrendale, Pa: Society of Automotive Engineers, Incorporated
Open this publication in new window or tab >>Measurement and characterisation of anti-shudder properties in wet clutch applications
2005 (English)In: 2005 SAE world congress: Detroit, Michigan, April 11 - 14, 2005, Warrendale, Pa: Society of Automotive Engineers, Incorporated , 2005Conference paper, Published paper (Refereed)
Abstract [en]

Wet clutches operating under low velocity and continuous sliding are increasingly important in vehicle transmissions. This presents new challenges in improving anti-shudder properties of the clutch system. In order to determine anti-shudder properties the friction-velocity relationship is generally examined. The friction-velocity characteristics are however influenced by the way they are measured, and the measurement methods differ between different standards and OEM approvals, thus making direct comparisons of the anti-shudder requirements difficult. This study investigates how different parameters influence anti- shudder properties. Results show how the obtained friction-velocity characteristics are influenced by the choice of different test procedures and parameters. Methods for presenting the anti-shudder properties are compared for the different cases and a method for evaluation of the properties is suggested. Presenting data using the proposed method makes comparison of results obtained from different measurements easier or even possible.

Place, publisher, year, edition, pages
Warrendale, Pa: Society of Automotive Engineers, Incorporated, 2005
Series
SAE technical Papers ; 2005-01-0878
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-34810 (URN)10.4271/2005-01-0878 (DOI)33144466180 (Scopus ID)91aa8d50-a301-11db-8975-000ea68e967b (Local ID)978-0-7680-1624-6 (ISBN)91aa8d50-a301-11db-8975-000ea68e967b (Archive number)91aa8d50-a301-11db-8975-000ea68e967b (OAI)
Conference
SAE World Congress : 11/04/2005 - 14/04/2005
Note
Godkänd; 2005; 20070111 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-01-14Bibliographically approved
Marklund, P., Mäki, R., Larsson, R., Höglund, E., Khonsari, M. M. M., Jang, J., . . . Ohlsson, R. (2005). Thermal influence on torque transfer of wet clutches in limited slip differential applications (ed.). In: (Ed.), (Ed.), Proceedings of the World tribology congress III: presented at ..., September 12 - 16, 2005, Washington, DC. Paper presented at World Tribology Congress : 12/09/2005 - 16/09/2005 (pp. 245-246). New York: American Society of Mechanical Engineers
Open this publication in new window or tab >>Thermal influence on torque transfer of wet clutches in limited slip differential applications
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2005 (English)In: Proceedings of the World tribology congress III: presented at ..., September 12 - 16, 2005, Washington, DC, New York: American Society of Mechanical Engineers , 2005, p. 245-246Conference paper, Meeting abstract (Other academic)
Abstract [en]

Wet clutches operating under low velocity and high load are studied with the aim of obtaining reliable models for the torque transfer during boundary lubrication conditions.

Place, publisher, year, edition, pages
New York: American Society of Mechanical Engineers, 2005
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-27392 (URN)10.1115/WTC2005-63532 (DOI)0d4c9610-c265-11db-9ea3-000ea68e967b (Local ID)0d4c9610-c265-11db-9ea3-000ea68e967b (Archive number)0d4c9610-c265-11db-9ea3-000ea68e967b (OAI)
Conference
World Tribology Congress : 12/09/2005 - 16/09/2005
Note
Godkänd; 2005; Bibliografisk uppgift: WTC2005-63532; 20070129 (parmar)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-03-09Bibliographically approved

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