• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 100
  • 43
  • 15
  • 13
  • 12
  • 5
  • 4
  • 3
  • 3
  • 3
  • 2
  • 1
  • Tagged with
  • 240
  • 49
  • 48
  • 39
  • 37
  • 33
  • 31
  • 31
  • 30
  • 28
  • 28
  • 28
  • 23
  • 23
  • 23
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Konstrukce malého parního motoru pro využití sluneční energie / Construction of small steam engine for the use of solar energy

Strava, Jan January 2020 (has links)
Possible modern application of piston steam engine is electricity production using steam made by solar energy. This diploma thesis focuses on designing such piston steam engine Described solution would be effective as an off grid electricity generator, because alternative source of steam could be added for occasions, when sunlight is not powerfull enough for steam production.
102

Pohon regulačního kruhu PVE Merkersbach / Drive of control ring PVE Merkersbach

Skoupý, Jiří January 2008 (has links)
This thesis is focused on determination of forces acting to regulation ring of water power plant Markersbach (Germany). Solution of the problem is realized for two variants of servomotors – with and without servomotors acting surfaces balancing. Next topics of this thesis are strenght calculation of piston rod and bottom of the servomotors. Minimalization of the size of servomotors plungers by change of regulation kinematics has been done and minimal pressure in the pressure tank is determined. At the conclusion of this thesis received results are mentioned and its interpretation has been done. This thesis is provided for company Litostroj Power, ČKD Blansko Engineering, a.s.
103

Modelování a tlumení vynucených pulzací / Simulation and damping of the excited pulsation

Kubis, Aleš January 2009 (has links)
The aim of diploma thesis is design math and numeric system, which simulate these features: model of threeplunger piston pump, system of piping and damping elements. This thesis also contains chapters, which describing numeric models of particular’s elements of system with charts of function dependencies from computation’s program. The last chapter contains numeric model of treeplunger piston pump without damping elements. Continuation of my diploma thesis should be a harmonized of damping elements and designed pump.
104

Návrh teplárny s pístovým parním motorem. / A proposal of power plant with steam engine.

Peterka, Lubomír January 2010 (has links)
The final thesis deals with the heating plant with piston steam engine design according to heat consumption background in the location of Velky Karlov and with the design of a heating scheme including its explicit parameters. Further on it deals with the possibilities of the heating plant output regulation and with the solution of natural gas and biomass heating plant operations aside the heating period.
105

Výpočtové modelování mechanických ztrát v klikovém mechanismu / Computational modeling of cranktrain mechanical losses

Smetana, Roman January 2010 (has links)
In the introduction of master’s thesis is introduced the common identification with basics of friction, wear and mechanical losses. Master’s thesis includes description of solving losses by help of the MBS software and analysis of mechanical losses in the crank train. In the last part of work is introduced design for decrease mechanical losses in the crank train. At the close of master’s thesis are reviewed records.
106

Využití vačkového mechanismu jako náhrady klikového ústrojí spalovacího motoru / Cam-shaft replacement of crank-shaft powertrain of combustion engine

Suk, Jakub January 2010 (has links)
Diploma thesis deal with possibility cam-shaft replacement of crank-shaft powertrain of combustion engine. In exordium work are designed basic engine data herewith type powertrain. Subsequently is designed several types stroke curves of lobe, after needs on course stroke. Further is in work elaborate engineering design body motor, in detail is solve construction body lobe. In last of capitol is evulate functionality virtual model. At the close are reviewed record and compared benefits and disavantages such engine type.
107

Condition Monitoring Systems for Axial Piston Pumps: Mobile Applications

Nathan J Keller (8770307) 02 May 2020 (has links)
Condition monitoring of hydraulic systems has become more available and inexpensive to implement. However, much of the research on this topic has been done on stationary hydraulic systems without the jump to mobile machines. This lack of research on condition monitoring of hydraulic systems on mobile equipment is addressed in this work. The objective of this work is to develop a novel process of implementing an affordable condition monitoring system for axial piston pumps on a mobile machine, a mini excavator in this work. The intent was to find a minimum number of sensors required to accurately predict a faulty pump. First, an expert understanding of the different components on an axial piston pump and how those components interact with one another was discussed. The valve plate was selected as a case study for condition monitoring because valve plates are a critical component that are known for a high percentage of failures in axial piston pumps. Several valve plates with various degrees of natural wear and artificially generated damage were obtained, and an optical profilometer was used to quantify the level of wear and damage. A stationary test-rig was developed to determine if the faulty pumps could be detected under a controlled environment, to test several different machine learning algorithms, and to perform a sensor reduction to find the minimum number of required sensors necessary to detect the faulty pumps. The results from this investigation showed that only the pump outlet pressure, drain pressure, speed, and displacement are sufficient to detect the faulty pump conditions, and the K-Nearest Neighbor (KNN) machine learning algorithms proved to be the least computationally expensive and most accurate algorithms that were investigated. Fault detectability accuracies of 100% were achievable. Next, instrumentation of a mini excavator was shown to begin the next phase of the research, which is to implement a similar process that was done on the stationary test-rig but on a mobile machine. Three duty cycle were developed for the excavator: controlled, digging, and different operator. The controlled duty cycle eliminated the need of an operator and the variability inherent in mobile machines. The digging cycle was a realistic cycle where an operator dug into a lose pile of soil. The different operator cycle is the same as the digging cycle but with another operator. The sensors found to be the most useful were the same as those determined on the stationary test-rig, and the best algorithm was the Fine KNN for both the controlled and digging cycles. The controlled cycle could see fault detectability accuracies of 100%, while the digging cycle only saw accuracies of 93.6%. Finally, a cross-compatibility between a model trained under one cycle and using data from another cycle as an input into the model. This study showed that a model trained under the controlled duty cycle does not give reliable and accurate fault detectability for data run in a digging cycle, below 60% accuracies. This work concluded by recommending a diagnostic function for mobile machines to perform a preprogrammed operation to reliably and accurately detect pump faults.
108

An Investigation of the Impact of the Elastic Deformation of the End case/Housing on Axial Piston Machines Cylinder Block/Valve Plate Lubricating Interface

Chacon, Rene, Ivantysynova, Monika January 2016 (has links)
The cylinder block/valve plate interface is a critical design element of axial piston machines. In the past, extensive work has been done at Maha Fluid Power Research center to model this interface were a novel fluid structure thermal interaction model was developed which accounts for thermal and elasto-hydrodynamic effects and has been proven to give an accurate prediction of the fluid film thickness. This paper presents an in-depth investigation of the impact of the elastic deformation due to pressure and thermal loadings of the end case/housing on the performance of the cylinder block/valve plate interface. This research seeks to understand in a systematic manner the sensitivity of the cylinder block/valve plate interface to the structural design and material properties. A comparison between simulations results is done by utilizing different end case designs and material compositions, both in the valveplate and end case solids.
109

Optimization of Axial Piston Units Based on Demand-driven Relief of Tribological Contacts

Haug, Stefan, Geimer, Marcus January 2016 (has links)
Markets show a clear trend towards an ever more extensive electronic networking in mobile and stationary applications. This requires a certain degree of electronic integration of hydraulic components such as axial piston pumps. Beside some wellknow approaches, the transmission of axial piston units still is relatively unexplored regarding electronification. Nonetheless there is a quite high potential to be optimized by electronic. In view of this fact, the present paper deals with the tribological contacts of pumps based on a demand driven hydrostatic relief. The contact areas at cylinder - distributor plate, cradle bearing and slipper - swash plate will be investigated in detail and it will be shown how the pump behavior can be improved considerably through a higher level of relief and a central remaining force ratio. The potential of optimization is to improve the efficiency, especially in partial loaded operation, power range, also for multi quadrant operation, precision and stability. A stable lubricating film for slow-speed running and for very high speeds at different pressures is ensured as well.
110

Tribolayer Formation on Bronze Cu Sn12Ni2 in the Tribological Contact between Cy linder and Cont rol Plate in an Axial Piston Pump with Swashplate Design

Paulus, Andreas, Jacobs, Georg January 2016 (has links)
The present study investigates the f ormation of tribolayers on bronze CuSn12Ni2. Two different test rigs are used, of which one is a sliding bearing test rig in order to perform lubricated thrust bearing tests. Bronze CuSn12Ni2 is used for the sliding elements and the counter body is made of C45 steel. In addition to that, an axial piston pump test rig was used to determine t he transfera bility of the results to th e axial pist on pump. The test conditions are set up in a way t hat the tribological load s in the contacts are similar to each other. Changes in the subsurfa ce morphology and the chemical composition of the tribolayer were analysed using electron pro be micro a nalysis (EPMA), trans mission electron microscopy (TEM), energy dispersive X -ray spectro scopy (EDS) and X-ra y photoelectron spectroscopy (XPS). Focused ion beam (FIB) milling was used to prepare site -specific TE M foils fro m the wear track. The formation of a nano scale tribolayer was associat ed with red uced wear, which leads to low leak age in the a xial piston pump. This tribolayer is enriched with oxygen, sulfur and zinc, which is an effect of tribochemical reactions of environment molecules and surface molecules.

Page generated in 0.0574 seconds