Die vorliegende Arbeit ist motiviert durch die breite Anwendung von Schwenkantrieben in vielfältigen konventionellen und neuen Technologiefeldern: In Windenergieanlagen führen Schwenkantriebe die Gondel samt Rotor der momentanen Windrichtung nach. Bei Radioteleskopen erlauben sie die hochpräzise azimutale Ausrichtung der Parabolantenne. Und im Sektor der Baumaschinen kommen sie zum Schwenken der Ausleger von Kranen und fördertechnischen Großgeräten zum Einsatz. Trotz des zunächst einfach erscheinenden Aufbaus der Schwenkantriebssysteme erweisen sich sowohl ihre mechanische Dimensionierung als auch ihre sichere Betriebsführung als herausfordernd. So belegen Messdaten und Betriebserfahrungen die Neigung der Antriebsstränge zu niederfrequenten Drehschwingungen. Außerdem treten große Spitzenlasten während der Schwenkrichtungsumkehr in den Getriebestufen auf. In diesem Forschungsbeitrag werden Methoden vorgestellt, mit denen elektromechanische Schwenkantriebssysteme modelliert, dynamisch analysiert und regelungstechnisch optimiert werden können. Dazu wird der schwingungsfähige mechanische Antriebsstrang eines Beispielschwenkwerks als detailliertes Mehrkörpersystem-Simulationsmodell abgebildet. Um auch Wechselwirkungen mit den elastischen Umgebungsstrukturen, der Antriebsregelung und den Betriebslasten zu erfassen, wird ein domänenübergreifendes Modellierungsvorgehen verfolgt. Es erfolgt eine messtechnische Validierung des mechatronischen Gesamtsystemmodells. Mit dem Vorliegen treffsicherer Systemmodelle eröffnet sich die Möglichkeit, ein modellbasiertes Mehrgrößenregelverfahren (LQG) auszulegen und simulativ zu erproben. Im Vergleich zur bisherigen proportional-integralen (PI) Antriebsregelung verspricht dies die aktive Dämpfung von Triebstrangschwingungen bei gleichzeitiger Erhöhung der Arbeitsgeschwindigkeit. Um für beliebige elastische Antriebssysteme das Optimierungspotenzial abschätzen zu können, erfolgt ein systematischer Vergleich der beiden Regelstrategien. Anschließend wird ein praxisnahes Vorgehen zur Regelungsauslegung vorgestellt. Besonderer Fokus liegt neben der Robustheit auch auf der begrenzten Anzahl verfügbarer Sensoren bei industriellen Antrieben. Zudem wird auch das oftmals beträchtliche Getriebespiel als signifikante Nichtlinearität der Regelstrecke berücksichtigt. Um eine Reduktion der Spitzenlasten während der Drehrichtungsumkehr des Schwenkantriebes zu erreichen, wird abschließend ein Konzept zur zeit- und belastungsoptimierten Durchquerung des Getriebespiels erarbeitet. Da die konventionelle Drehzahlregelung des Schwenkantriebs hierbei nur um ein Zusatzmodul erweitert wird, bietet sich das Vorgehen insbesondere zur Ertüchtigung bestehender Antriebe an.:1 Einleitung 1.1 Motivation 1.2 Konkretisierte Problemstellung 1.3 Aufbau der Arbeit 2 Grundlagen und Forschungsstand 2.1 Modellbildung und Simulation von Antriebssystemen 2.1.1 Mehrkörpersystem-Simulation von Antriebssystemen 2.1.2 Modellbildung von Schwenkwerken 2.2 Anwendungsbereiche von Schwenkantrieben 2.2.1 Turmdrehkrane 2.2.2 Windenergieanlagen 2.2.3 Radioteleskope 2.2.4 Baumaschinen 2.3 Untersuchtes Beispielschwenkwerk 2.3.1 Antriebstechnik 2.3.2 Bisherige Untersuchungen an Schaufelradbaggern 3 Modellbildung und Simulation von Schwenkwerken 3.1 Mechanische Komponenten 3.1.1 Schwenkantriebe 3.1.2 Elastische Tragstrukturen am Getriebeausgang 3.1.3 Weitere Antriebsstränge des Gesamtsystems 3.2 Elektrische und informationsverarbeitende Domäne 3.2.1 Aktorik – Elektrische Antriebsmaschine 3.2.2 Informationsverarbeitung – Antriebsregelung 3.2.3 Informationserfassung – Winkelmesssysteme 3.3 Betriebslasten 3.3.1 Quasistatische Lasten 3.3.2 Simulation der bodenmechanischen Interaktion bei Schaufelradbaggern 3.4 Messdatengestützte Validierung der Systemmodelle 3.4.1 Beschreibung des Messaufbaus 3.4.2 Betriebsschwingungsanalyse 3.4.3 Validierung Schwenkwerk – Reversiervorgang 3.4.4 Validierung Gesamtsystem – Grab-Schwenk-Prozess 3.5 Ableitung eines mechanischen Minimalmodells 3.6 Zwischenfazit 4 Drehzahlregelung elastischer Antriebssysteme 4.1 Allgemeine Grundlagen 4.1.1 Führungs- und Störungsverhalten 4.1.2 Stabilität und Performanz 4.1.3 Singulärwertzerlegung von Frequenzgangmatrizen 4.2 Motor mit elastisch gekoppeltem Abtrieb 4.2.1 Proportional-Integrale Eingrößenregelung 4.2.2 Zustandsregelung 4.2.3 Generalisierter Vergleich der Regelungskonzepte 4.3 Erweiterung auf Mehrmotorenantriebe 4.4 Konzeption und Umsetzung einer Zustandsregelung 4.4.1 Auslegung eines optimalen Zustandsreglers 4.4.2 Rekonstruktion des Zustandsvektors bei Antrieben mit Verzahnungsspiel 4.4.3 Analyse des Gesamtkonzeptes 4.5 Zwischenfazit 5 Verzahnungsspiel in elastischen Antriebssträngen 5.1 Ursachen 5.2 Modellbildung 5.2.1 Klassische Modellierung als Totzone 5.2.2 Erweitertes Spielmodell nach Nordin 5.2.3 Hysterese 5.3 Auswirkungen 5.3.1 Antriebsstrangbelastung 5.3.2 Folgen auf Gesamtsystemebene 5.3.3 Zwischenfazit 5.4 Regelstrategien für spielbehaftete Antriebe 5.4.1 Lineare Eingrößenregelung 5.4.2 Mehrgrößenregelung – Zustandsraummethoden 5.4.3 Umschaltende lineare Regler 5.4.4 Modellprädiktive Regelung 5.4.5 Invertierung der Nichtlinearität 5.4.6 Zwischenfazit 5.5 Konzeption und Umsetzung einer Strategie zum lastminimierten Spieldurchlauf 5.5.1 Optimaltrajektorie zur Spieldurchquerung 5.5.2 Realisierung der Spieldurchquerung 5.5.3 Simulative Verifizierung 6 Zusammenfassung und Ausblick / The present work is motivated by the wide application of slewing drives and yaw drives in a variety of conventional and emerging fields of technology: In wind turbines, yaw drives track the nacelle and rotor according to the current wind direction. In radio telescopes, they enable high-precision azimuthal alignment of the parabolic antenna. And in the construction machinery sector, they are used to rotate the booms of cranes and bucket wheel excavators. At first glance the design of slewing drive systems seems to be simple, but their mechanical dimensioning as well as their reliable operation turn out to be challenging. Measurement data and operating experience show that the drive trains are prone to low-frequency torsional vibrations. In addition, large peak loads occur during reversals of the slewing direction. In this thesis, methods are presented for the modeling, dynamical analysis and control optimization of electromechanical slewing drive systems. Therefore, the mechanical drive train of an exemplary slewing gearbox unit is represented as a detailed multibody system simulation model. A cross-domain modeling approach is pursued in order to capture interactions with the surrounding flexible structures, the drive control and the operating loads as well. The resulting overall mechatronic system model is validated by measurement. The development of accurate system models enables a model-based multivariable control method (LQG) to be designed and tested by simulation. Compared to conventional proportional integral (PI) drive control, this promises active damping of drive train vibrations while simultaneously increasing the operating speed. To estimate the optimization potential for arbitrary elastic drive systems, a systematic comparison of both control strategies is performed. Subsequently, a practical procedure for designing the control system is presented. In addition to robustness, special focus is placed on the limited number of available sensors in industrial drives. Furthermore, the considerable gear backlash is also accounted for as a significant nonlinearity of the controlled system. To reduce peak loads during the reversal of the rotational direction, a novel approach for time- and load-optimized traversing of the gearbox backlash is developed. Since the conventional speed control algorithm is only extended by an additional module, the method is particularly suitable for retrofitting existing drives.:1 Einleitung 1.1 Motivation 1.2 Konkretisierte Problemstellung 1.3 Aufbau der Arbeit 2 Grundlagen und Forschungsstand 2.1 Modellbildung und Simulation von Antriebssystemen 2.1.1 Mehrkörpersystem-Simulation von Antriebssystemen 2.1.2 Modellbildung von Schwenkwerken 2.2 Anwendungsbereiche von Schwenkantrieben 2.2.1 Turmdrehkrane 2.2.2 Windenergieanlagen 2.2.3 Radioteleskope 2.2.4 Baumaschinen 2.3 Untersuchtes Beispielschwenkwerk 2.3.1 Antriebstechnik 2.3.2 Bisherige Untersuchungen an Schaufelradbaggern 3 Modellbildung und Simulation von Schwenkwerken 3.1 Mechanische Komponenten 3.1.1 Schwenkantriebe 3.1.2 Elastische Tragstrukturen am Getriebeausgang 3.1.3 Weitere Antriebsstränge des Gesamtsystems 3.2 Elektrische und informationsverarbeitende Domäne 3.2.1 Aktorik – Elektrische Antriebsmaschine 3.2.2 Informationsverarbeitung – Antriebsregelung 3.2.3 Informationserfassung – Winkelmesssysteme 3.3 Betriebslasten 3.3.1 Quasistatische Lasten 3.3.2 Simulation der bodenmechanischen Interaktion bei Schaufelradbaggern 3.4 Messdatengestützte Validierung der Systemmodelle 3.4.1 Beschreibung des Messaufbaus 3.4.2 Betriebsschwingungsanalyse 3.4.3 Validierung Schwenkwerk – Reversiervorgang 3.4.4 Validierung Gesamtsystem – Grab-Schwenk-Prozess 3.5 Ableitung eines mechanischen Minimalmodells 3.6 Zwischenfazit 4 Drehzahlregelung elastischer Antriebssysteme 4.1 Allgemeine Grundlagen 4.1.1 Führungs- und Störungsverhalten 4.1.2 Stabilität und Performanz 4.1.3 Singulärwertzerlegung von Frequenzgangmatrizen 4.2 Motor mit elastisch gekoppeltem Abtrieb 4.2.1 Proportional-Integrale Eingrößenregelung 4.2.2 Zustandsregelung 4.2.3 Generalisierter Vergleich der Regelungskonzepte 4.3 Erweiterung auf Mehrmotorenantriebe 4.4 Konzeption und Umsetzung einer Zustandsregelung 4.4.1 Auslegung eines optimalen Zustandsreglers 4.4.2 Rekonstruktion des Zustandsvektors bei Antrieben mit Verzahnungsspiel 4.4.3 Analyse des Gesamtkonzeptes 4.5 Zwischenfazit 5 Verzahnungsspiel in elastischen Antriebssträngen 5.1 Ursachen 5.2 Modellbildung 5.2.1 Klassische Modellierung als Totzone 5.2.2 Erweitertes Spielmodell nach Nordin 5.2.3 Hysterese 5.3 Auswirkungen 5.3.1 Antriebsstrangbelastung 5.3.2 Folgen auf Gesamtsystemebene 5.3.3 Zwischenfazit 5.4 Regelstrategien für spielbehaftete Antriebe 5.4.1 Lineare Eingrößenregelung 5.4.2 Mehrgrößenregelung – Zustandsraummethoden 5.4.3 Umschaltende lineare Regler 5.4.4 Modellprädiktive Regelung 5.4.5 Invertierung der Nichtlinearität 5.4.6 Zwischenfazit 5.5 Konzeption und Umsetzung einer Strategie zum lastminimierten Spieldurchlauf 5.5.1 Optimaltrajektorie zur Spieldurchquerung 5.5.2 Realisierung der Spieldurchquerung 5.5.3 Simulative Verifizierung 6 Zusammenfassung und Ausblick

This thesis presents an experimental research study aimed at identifying the optimal mechano-chemical surface treatment for powder metallurgy gears utilized in electric vehicles (EVs). The primary objective of the study is to determine the most effective surface treatment method in terms of enhancing gear transmission efficiency. The experiments utilise a specialized FZG test rig, which allows for comprehensive testing under realistic operating conditions. In addition, a surface roughness measurement device is used to evaluate the impact of the surface treatments on the gear's surface characteristics. The results obtained from the experiments reveal a particular type of surface treatment as the most effective among the test samples considered within the scope of the thesis, as it significantly improves gear transmission efficiency. These findings contribute to the advancement of surface treatment techniques for powder metallurgy gears used in EVs, aiding in the development of more efficient and high-performing gear systems for electric mobility. / Denna avhandling presenterar en experimentell forskningsstudie som syftar till att identifiera den optimala mekano-kemiska ytbehandlingen för pulvermetallurgiväxlar som används i elfordon (EV). Det primära syftet med studien är att fastställa den mest effektiva ytbehandlingsmetoden när det gäller att förbättra effektiviteten i växelöverföringen. Experimenten utförs med hjälp av en specialiserad FZG-testrigg, som möjliggör omfattande tester under realistiska driftsförhållanden. Dessutom används en ytråhetsmätningsanordning för att utvärdera effekten av ytbehandlingarna på kugghjulets ytegenskaper. Resultaten från experimenten avslöjar en viss typ av ytbehandling som den mest effektiva bland de testprover som betraktas inom ramen för avhandlingen, eftersom den avsevärt förbättrar växeltransmissionens effektivitet. Dessa fynd bidrar till utvecklingen av ytbehandlingstekniker för pulvermetallurgiska redskap som används i elbilar, vilket hjälper till att utveckla mer effektiva och högpresterande växelsystem för elektrisk mobilitet.

No description available.

No description available.

<p dir="ltr">This research developed a lumped volume-based coupled simulation model for gear pumps and motors, which is employed to analyze a reference machine of a compensated crescent- type internal gear pump. The model is composed of simultaneous simulations of the pump fluid domain pressure, lubricating films, and dynamics of the moving components.</p><p dir="ltr">The simulation model developed includes four major novel contributions.</p><p dir="ltr">1. A coupled simulation model was developed for the reference machine which provides (a) a lumped parameter simulation of the fluid pressure within the inter-teeth volumes, (b) CFD simulations of the lubricating interfaces, and (c) a simulation of the micromotion of the pressure compensating components and gear bodies. The simulation tool is developed in C++ and constitutes the simulation core of Multics for internal gear pumps. The model achieved volumetric and mechanical predictions for the reference type of machine, which are validated via experimental investigations.</p><p dir="ltr">2. A flexible pressure solver was established to solve the pressure transience in the fluid domain in gear pumps with general CV geometry exemplified in the reference machine. The approach allows for ample freedom in defining control volumes, including possible volume discontinuities. The new formulation, derived from mass conservation, avoids the numerical evaluation of the volume derivatives so that it allows for simulating a control volume layout with sudden shape changes. The new formulation also considers the sliding motion from volume boundaries when evaluating internal flows, which improves the accuracy of the control volume pressure solutions. The effectiveness of the proposed formulation was examined by applying the method to the simulation of the reference machine. Compared with the state-of-the-art simulations, several improvements in the pressure simulation were observed : (i) the proposed formulation provides free-of-spike fluid pressure simulations, even for discontinuous volumes; (ii) the proposed formulation properly captures the flow component between volumes that is caused by the volume boundary motions, a term previously neglected, which affects the pressure evaluation accuracy, especially in gear meshing zone.</p><p dir="ltr">3. The swift film coupling algorithm proposes a novel artificial inertia damping-based method (AIDM) to simulate this coupling. The proposed method considers modifying the physical body dynamics with artificial inertia and damping values that could achieve significant numerical solver accelerations while maintaining extremely low errors. The artificial inertia and damping are determined based on the instantaneous physical system’s Jacobian so that the first-order dynamics in the solution can be conserved from the original dynamic system. The solver acceleration capability is quantified in time-discretization-based derivations, where additional guidelines for determining the artificial inertia and damping values are found. The proposed approach is used to simulate two model problems for a 1-D slider pad under periodic loading conditions, where one pad is fixed inclined and the other free to move vertically and rotate about its center. Simulation results reported an error lower than 0.01 μm in the gap height geometry prediction by the proposed AIDM approach compared to the state-of-the-art Reynolds film damping-based method (RDM). Meanwhile, the numerical solver speed improved 1000 times for the fixed incline pad problem and one hundred thousand times for the free-to-float pad problem. Derivations showed that additional acceleration potential can be achieved in realistic mechanical systems where a higher degree of freedom is present in the body motions. The error behavior of the proposed AIDM approach is discussed, showing the error is positively related to the absolute magnitude of the modification parameter ϕ used for calculating the artificial inertia and damping, and the error is related to the validity of the linearization assumption on the system dynamics.</p><p dir="ltr">4. Based on a novel experimental set-up to measure the filling characteristics of an internal gear pump under induced gaseous cavitation. An integrated simulation approach was proposed to study the incomplete filling behavior in positive displacement machines. The approach consists of (a) a 1st order predictive model for evaluating the amount of undissolved gas at the pump inlet from the circuit pressure loss, (b) a gas-equilibrium-based cavitation model for predicting the pressure transience in the pump fluid domain, (c) a lumped volume based pump flow evaluation. Experiments performed over a wide range of operating conditions validated the deployment of the first-order gas release prediction (with 8 s time constant for fluid with 6 % total air). The complete simulation approach was validated via a good match with the measured volumetric efficiency for both low-speed and high-speed conditions.</p><p dir="ltr">The reference compensated crescent-type internal gear pump (CCIGP) unit was simulated with the full scope coupled simulation model, with which the methods proposed in this thesis research were validated with experiments. Simulation results matched with volumetric efficiency as well as mechanical efficiency. The model also reports a breakdown of the energy consumption within the reference CCIGP, which promotes the understanding of the operation of the reference machine.</p>

This thesis reports the investigation into the modelling and simulation of an aircraft tyre and wheel assembly in finite element environment. The finite element simulations basing on aircraft tyre test and operational scenarios could predict the loads transferred from tyre and the stresses distributed to the wheel rim. The virtual analysis could assess the safety criteria of different tyre structures, which would lead to the cost and time circle reduction in tyre R&D process. An H41x16.0R20 radial ply aircraft test tyre and its corresponding test wheel, provided by Dunlop Aircraft Tyres Limited, are adopted as the subject of this research. The material properties, especially the rubber and fabric materials, have been investigated. The finite element hyperelastic models have been utilized to represent rubbers and been correlated to experimental data. The 2D and 3D finite element tyre models, along with the finite element wheel models are created in the commercial finite element code, LS-Dyna. The finite element models have been validated with either industrial standardised simulation results or experimental data. Basing on the validated models, simulations that duplicating static test and dynamic operational scenarios have been developed. The researches have provided knowledge in comparing single and double bead tyre designs with respect to wheel loading mechanisms. The computational model also allowed manufacturers to assess the performance and safety criteria of a particular tyre at its design stage. The development of such models would add to the general drive towards the use of more virtual prototypes in an area traditionally reliant on experimental testing.

Powder metallurgy (PM) is usually used in manufacturing parts with complex geometries, such as gears and structural parts. The main attractions of PM are the high rate of material utilization, environmental friendliness of production, economic advantages (especially for complex geometries), and possibility of obtaining lighter components. To find a wide range of applications and compete with regular steel gears, PM gear transmissions should have good transmission efficiency and wear properties. Furthermore, they should have low contact noise and adequate surface fatigue properties. Because of the porosity structure of PM gears both on gear flanks and in the body, the friction and wear properties of PM gear flank contacts differ somewhat from those of regular steel gears.    This doctoral thesis examines the efficiency and wear properties of PM gears. Paper A compares the wear, friction, and damage mechanism properties of two sintered gear materials with those of a standard gear material. Paper B deals with the gear mesh torque loss mechanism of PM and regular steel gears by combining both pin-on-disc frictional and FZG efficiency tests. Paper C comparatively examines the efficiency of PM and regular steel gears by conducting FZG gear efficiency tests. Paper D focuses on the wear and friction properties of PM and regular steel gear materials treated using the triboconditioning process. Paper E studies the friction and wear properties attributable to different pore sizes in PM gear materials.    The results indicate that regular steel meshed with PM gear material and PM meshed with PM gear material are good candidate combinations for gear transmissions. This is because the porosities of PM material can lower the friction coefficient while the wear rate can be the same as or even better than that of regular steel contacts. The triboconditioning process enhances the wear resistance and reduces the friction coefficient of the PM gear material. The friction and wear coefficients of PM meshed with PM gear material display increasing trends with increasing pore size. The friction and wear coefficients of regular steel meshed with PM gear material display decreasing trends with increasing pore size. / <p>QC 20160523</p>

In all common hydrostatic pumps, compressibility affects the commutation phases of the displacing chambers, as they switch their connection from/to the inlet to/from the outlet port, leading to pressure peaks, localized cavitation, additional port flow fluctuations and volumetric efficiency reduction. In common pumps, these effects are reduced by proper grooves that realizes gradual port area variation in proximity of these transition regions. This paper presents a method to automatically find the optimal designs of these grooves, taking as reference the case of external gear pumps. The proposed procedure does not assume a specific geometric morphology for the grooves, and it determines the best feasible designs through a multi-objective optimization procedure. A commercial gear pump is used to experimentally demonstrate the potentials of the proposed method, for a particular case aimed at reducing delivery flow oscillations.

This paper describes a novel concept for a low cost variable delivery external gear pump (VD-EGP). The proposed VD-EGP is based on the realization of a variable timing for the connections of the internal displacement chambers with the inlet and outlet ports. With respect to a standard EGP, an additional element (slider) is used along with asymmetric gears to realize the variable timing principle. Previously performed tests confirmed the validity of the concept, for a design capable of varing the flow in the 65%-100% range. Although the VD-EGP concept is suitable for various flow control system typologies (manual, electro-actuated, hydraulically flow- or pressure- compensated), this paper particularly details the design and the test results for a prototype that includes both a manual flow control system and a pressure compensator. Flow vs pressure and volumetric efficiency curves are discussed along with transient (outlet flow fluctuation) features of the VD-EGP.

<p>The general trend in gear industry, today, is an increased focus on gear transmission efficiency. Gear transmission efficiency losses arise from loaded and unloaded gear contacts, seals, lubricant and bearings. One way of minimising the losses is to lower the lubricant viscosity. This will reduce the speed dependent losses. However, the load dependent losses might increase. To avoid this, the ratio between lubricant film thickness and surface roughness must be maintained, which can be fulfilled by producing smoother gear surfaces. As a starting point for this realisation process, the present manufacturing processes, the design tools and the characteristics of the gear flank interface must be further investigated and developed. This must be achieved with an emphasis on economic production.</p><p>This thesis focuses on our understanding of how different gear manufacturing methods —particularly the contribution of the running-in process—affect the surface characteristics, with the view of increasing gearbox efficiency. The thesis consists of a summary and three appended papers.</p><p>Paper A and paper B discuss the relationship between design parameters and real gear wheel surfaces manufactured with different manufacturing methods. The research hypothesis was that the contact area ratio is a descriptive parameter for the contact condition. Paper A deals with the influence of manufacturing method on the initial contact conditions and also serves as a validation of the simulation program used. The emphasis in Paper B is the changes that occur during running-in, and to correlate these changes to design requirements. Paper C approaches the influences of manganese phosphate-coating and lubricants with respect to friction and the risk of scuffing at the initial contact.</p><p>The main conclusions of this thesis are that the contact area ratio presents a descriptive measure of how surface topography influences the contact, seen at both a global (form deviation) and local (roughness) level. The surface topography caused by the manufacturing method has a significant influence on the contact area ratio. This is an important result, since neither national standards nor commercially available gear evaluation programs handle surface topography on the local scale. Shaving was found to have the highest contact area ratio, and should therefore be the best choice if deviations from case hardening could be minimised. It is also confirmed that gear-like surfaces coated with manganese phosphate have a low coefficient of friction, and raise the limiting load for scuffing failure enormously compared to the ground equivalent.</p> / QC 20100518 / KUGG / Sustainable gear transmission realization