Lukas Merkle

Zusammenfassung

Many failures of wind turbines are due to drive failures caused by pitting. Each failure can be associated with high repair costs and time-consuming repair work. This particularly applies to offshore facilities. For these reasons, increasing the remaining useful life of wind power drives is essential to leave a minimal ecological footprint by simultaneously increasing power output. Pitting damage occurs first on the weakest tooth. Artificial Intelligence is used to apply a local load reduction to a pre-damaged tooth and delay degradation. The other intact teeth compensate for the load reduction in order to achieve a constant average power. To increase the service life of wind power drives and to avoid unexpected failures an adaptive operating strategy can be implemented. With a test gearbox the adaptive operating strategy is examined on a test bench. The test gearbox is equipped with test gears with varying degrees of pre-damage. The objective of the examinations on the test gearbox is to detect pitting damage at the earliest possible stage. The earlier damage is detected, the greater the potential for increasing useful life. For detection, multiple high frequency acceleration sensors are integrated in the gearbox. Using machine learning approaches, the vibration data are analyzed. By means of anomaly detection damage can be identified during operation. Using torque control on the test bench, the load on pre-damaged teeth is minimized depending on the detected damage. In summary, the findings on the test gearbox will provide fundamental knowledge that will enable the implementation of the adaptive operating strategy inwind power drives.

Zusammenfassung

Elastomere Radial-Wellendichtungen werden in fast jedem antriebstechnischen Aggregat eingesetzt. Ohne Abdichtung der Wellendurchtrittstelle ist ein Betrieb unmöglich. Obwohl die Dichtringe millionenfach eingesetzt werden, kommt es immer wieder zum Systemschaden „Leckage“. Die Dichtringe zeigen als tribologischen Primärschaden beispielsweise Verhärtung, Risse oder exzessiven Verschleiß. Eine Berechnung der Lebensdauer ist für RWDR nach wie vor nicht möglich, daher sind Prüfläufe das einzige Werkzeug zur sicheren Auslegung von Dichtsystemen. Die Forschungsvorhaben der Projektreihe 696 haben zum Ziel, KmU und anderen Unternehmen einen Leitfaden zur systematischen Prüfung von Dichtsystemen zur Verfügung zu stellen. Wichtigstes Werkzeug dafür ist der vollständige Gesamtschadenskatalog. Das Wissen aus 696 I bis IV zum Thema Schadenanalyse, einstufigen und wechselnden Belastungen sowie zur Validierung der Ergebnisse unter industriellen Einsatzbedingungen wird in diesem Gesamtbericht zusammengeführt. Die Unternehmen können mit dem Leitfaden Schadensfälle analysieren und angepasste Kollektive für tribometrische Versuche erstellen. Damit können Dichtsysteme untersucht und optimiert werden. Leckage und Imageverlust können sicher vermieden werden. Die Erkenntnisse sind digitalisiert und stehen für den Wissenstransfer zur Verfügung. In der Projektreihe 696 wurden 278 Prüfläufe mit einer kumulierte Versuchslaufzeit von 108.117,4 h (= 12,3 Jahre) und einem kumulierten Laufweg von fast 2 Millionen km individuell ausgewertet. Das Ziel des Forschungsvorhabens wurde erreicht.

Zusammenfassung

Radial lip seals are used in various sizes and designs to seal shaft interfaces. In contrast to other sealing systems, elastomeric radial lip seals have a back-pumping capability. Fluid is pumped under the sealing edge from the air side to the fluid side. The simplest method for measuring the back-pumping rate is the converse installation of the radial lip seal. This paper describes the current state of the art in back-pumping rate measurement. It shows the advantages over other methods and the limitations of the method. For the converse installation, there was always the assumption of hydrodynamic lubrication. This means there would be only minimal initial run in effects and no further wear. Current research work however, question this assumption. To analyze the wear formation during back-pumping rate measurements, various long-term tests were carried out. The resulting wear is compared with identical tests in normal installation.

Zusammenfassung

Elastomeric rotary shaft seals are a common seal type for various industrial applications. They are comparably cheap and easy to use and offer an overall good performance. But the wear behavior of these sealing systems is not fully understood and not predictable so far. If a lip seal fails, it causes high maintenance costs and environmental damage. In this article, various tribological conditions are considered. For this purpose, the sealing systems are tested with multiple operating conditions relevant to practice. Three test series are conducted with rotary shaft seals BAUM5X7 75FKM585 on plunge ground shafts. The tests are carried out with two different circumferential velocities of the shaft (4.2 and 10 m/s), three different oil sump temperatures (40, 80, and 120 °C), two different lubricant types (FVA 3 and PG 3), and five different test durations (between 100 and 625 h). For a complete acquisition of the system condition, all shaft surfaces are measured in 2D and 3D before and after the test runs and the wear of the sealing edges is evaluated with a recently developed laser line triangulation method on the complete circumference of the sealing rings. Results show large amounts of wear, depending significantly on the operating conditions. A strong correlation of the wear effects in the tribocontact area of the sealing system becomes evident. This article helps to understand and avoid critical operating conditions concerning abrasive wear.

Zusammenfassung

In the event of damage to sealing systems, expert knowledge in dealing with these problems is often not available to many industrial users. The development engineer is faced with the question of improving the product to meet the new requirements. The aim of this publication is to provide a proven guide for dealing with problematic sealing systems.

Zusammenfassung

Radial lip seals are a common seal type for various industrial applications. In retarder breaking systems for commercial vehicles, radial lip seals are exposed to very fast changing oil sump temperatures. Due to increasing demands, the elastomer seals are increasingly failing premature in such applications. It is assumed that this is caused in particular by the very high temperature gradients, that result from the fact that a lot of braking power is dissipated within a short time. This is the case, for example, when braking while driving downhill with heavy loads. Since the temperature gradient is of minor importance in many applications, there are no publications regarding the specific influence of high temperature gradients on the function of radial shaft seals. Therefore, a test rig with advanced heating and cooling capacities is developed. A comprehensive test series is carried out, with the main focus on the influence of high temperature gradients on the wear behavior of the seals. Test results show, that different temperature levels lead to a significant change of the wear behavior. Additionally, fast changing temperatures are adding additional tribological stress to the sealing system.

Zusammenfassung

Radial lip seals are a common seal type for drive units in various industrial applications. Environmentally friendly operation strategies require these drive units to be driven on demand in short time duty. The sealing systems have to deal with fast changing oil sump temperatures. This cannot be reproduced on usual test rigs. Firstly, a test rig with advanced heating and cooling capacities was developed. Then, comprehensive test series were carried out. As expected, test results show, different constant temperature levels lead to a significant change of wear. Furthermore, fast changing temperatures are adding additional tribological stress to the sealing system.