Experimental analysis of oil flow and drag torque generation in disengaged wet clutches
Abstract Fundamental knowledge of the oil flow in a disengaged wet clutch is essential for optimizing the cooling performance and the drag losses. However, no fundamental information on the oil flow and drag torque generation is available for dip-lubricated wet clutches. Therefore, the oil flow and...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2023-10-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-023-43695-6 |
| _version_ | 1797452570828996608 |
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| author | Lukas Pointner-Gabriel Elias Schermer Thomas Schneider Karsten Stahl |
| author_facet | Lukas Pointner-Gabriel Elias Schermer Thomas Schneider Karsten Stahl |
| author_sort | Lukas Pointner-Gabriel |
| collection | DOAJ |
| description | Abstract Fundamental knowledge of the oil flow in a disengaged wet clutch is essential for optimizing the cooling performance and the drag losses. However, no fundamental information on the oil flow and drag torque generation is available for dip-lubricated wet clutches. Therefore, the oil flow and drag torque generation in the sub-millimeter gap of a dip-lubricated wet clutch was experimentally investigated for three practically relevant oil levels. To enable optical access to the gap, transparent components were used. Further, a high-speed camera was used to capture the oil flow in the gap and grooving. Independent of the set oil level, the gap is oil-filled at low differential speeds, resulting in a single-phase flow. The drag torque increases approximately linearly with increasing differential speed due to the fluid shearing. In certain regions of the waffle grooving, air bubbles form locally. The air bubbles preferably occur in the grooves oriented in the radial direction, while the grooves oriented in the peripheral direction are filled with oil. Above a certain differential speed, the oil is continuously displaced from the gap, starting from the inside, due to the increasing centrifugal force. Consequently, the drag torque increases in a degressive manner until a maximum value is finally reached. The ongoing displacement of oil from the gap eventually results in a decrease in the drag torque. A steady drag torque is generated only when the oil is almost entirely displaced from the gap. Since the oil displacement from the gap already commences at a low differential speed, the cooling performance is limited for dip-lubricated wet clutches. The continuous displacement of oil from the gap can be held up, among other things, by increasing the oil level. |
| first_indexed | 2024-03-09T15:10:35Z |
| format | Article |
| id | doaj.art-3a2f07a9321e4f05b029bd77eda67cbe |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-03-09T15:10:35Z |
| publishDate | 2023-10-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-3a2f07a9321e4f05b029bd77eda67cbe2023-11-26T13:22:40ZengNature PortfolioScientific Reports2045-23222023-10-0113111510.1038/s41598-023-43695-6Experimental analysis of oil flow and drag torque generation in disengaged wet clutchesLukas Pointner-Gabriel0Elias Schermer1Thomas Schneider2Karsten Stahl3Department of Mechanical Engineering, School of Engineering and Design, Gear Research Center (FZG), Technical University of MunichDepartment of Mechanical Engineering, School of Engineering and Design, Gear Research Center (FZG), Technical University of MunichDepartment of Mechanical Engineering, School of Engineering and Design, Gear Research Center (FZG), Technical University of MunichDepartment of Mechanical Engineering, School of Engineering and Design, Gear Research Center (FZG), Technical University of MunichAbstract Fundamental knowledge of the oil flow in a disengaged wet clutch is essential for optimizing the cooling performance and the drag losses. However, no fundamental information on the oil flow and drag torque generation is available for dip-lubricated wet clutches. Therefore, the oil flow and drag torque generation in the sub-millimeter gap of a dip-lubricated wet clutch was experimentally investigated for three practically relevant oil levels. To enable optical access to the gap, transparent components were used. Further, a high-speed camera was used to capture the oil flow in the gap and grooving. Independent of the set oil level, the gap is oil-filled at low differential speeds, resulting in a single-phase flow. The drag torque increases approximately linearly with increasing differential speed due to the fluid shearing. In certain regions of the waffle grooving, air bubbles form locally. The air bubbles preferably occur in the grooves oriented in the radial direction, while the grooves oriented in the peripheral direction are filled with oil. Above a certain differential speed, the oil is continuously displaced from the gap, starting from the inside, due to the increasing centrifugal force. Consequently, the drag torque increases in a degressive manner until a maximum value is finally reached. The ongoing displacement of oil from the gap eventually results in a decrease in the drag torque. A steady drag torque is generated only when the oil is almost entirely displaced from the gap. Since the oil displacement from the gap already commences at a low differential speed, the cooling performance is limited for dip-lubricated wet clutches. The continuous displacement of oil from the gap can be held up, among other things, by increasing the oil level.https://doi.org/10.1038/s41598-023-43695-6 |
| spellingShingle | Lukas Pointner-Gabriel Elias Schermer Thomas Schneider Karsten Stahl Experimental analysis of oil flow and drag torque generation in disengaged wet clutches Scientific Reports |
| title | Experimental analysis of oil flow and drag torque generation in disengaged wet clutches |
| title_full | Experimental analysis of oil flow and drag torque generation in disengaged wet clutches |
| title_fullStr | Experimental analysis of oil flow and drag torque generation in disengaged wet clutches |
| title_full_unstemmed | Experimental analysis of oil flow and drag torque generation in disengaged wet clutches |
| title_short | Experimental analysis of oil flow and drag torque generation in disengaged wet clutches |
| title_sort | experimental analysis of oil flow and drag torque generation in disengaged wet clutches |
| url | https://doi.org/10.1038/s41598-023-43695-6 |
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