A continuously variable hydraulic pressure converter based on high-speed on–off valves

Mechatronics ◽  
2011 ◽  
Vol 21 (8) ◽  
pp. 1298-1308 ◽  
Author(s):  
Feng Wang ◽  
Linyi Gu ◽  
Ying Chen
Keyword(s):  
High Speed ◽  
Hydraulic Pressure ◽  
Pressure Converter

Switchmode Hydraulic Power Supply Theory

2005 ◽  
Author(s):  
Jianwei Cao ◽  
Linyi Gu ◽  
Feng Wang ◽  
Minxiu Qiu
Keyword(s):  
Flow Rate ◽  
Dynamic Characteristics ◽  
Power Supply ◽  
Power Loss ◽  
High Speed ◽  
Hydraulic Pressure ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Hydraulic Power ◽  
Supply Pressure

Switchmode hydraulic power supply is a new kind of energy-saving pressure converting system, which is originally proposed by the authors. It is mainly applied in multiple-actuator hydraulic systems, and installed between hydraulic pump and actuators (one switchmode hydraulic power supply for one actuator). It can provide pressure or flow rate that is adapted to the consumption of each actuator in the system by boosting or bucking the pressure, with low power loss, and conveniently, through high-speed switch valves, just like a hydraulic pressure transformer. There are two basic types of switchmode hydraulic power supply: pressure boost and pressure buck. Their structures and working principles are introduced. The dynamic characteristics of two typical types of switchmode hydraulic power supply, the pressure boost type and the pressure buck type, were analyzed through simulations and experiments. The performances were evaluated, and improvements on the efficiency of switchmode hydraulic power supply were proposed.

Research on Electro-Hydraulic Control of Propellers of the Underwater Vehicles With Switch-Mode Hydraulic Power Supply

2006 ◽  
Author(s):  
Jianwei Cao ◽  
Linyi Gu ◽  
Feng Wang ◽  
Ying Chen
Keyword(s):  
Control System ◽  
Power Supply ◽  
High Speed ◽  
Weight Ratio ◽  
Pulse Frequency ◽  
Hydraulic Pressure ◽  
Hydraulic Control ◽  
Pulse Frequency Modulation ◽  
Hydraulic Power ◽  
Switch Mode

Switch-mode hydraulic power supply is a hydraulic pressure converting unit made of some distributed hydraulic components, which can boost or buck hydraulic pressure continuously with low power loss (about 20%)and continuous flow-rate. There are two types of switch-mode hydraulic power supply, pressure boost and pressure buck. (see "Switch-mode Hydraulic Power Supply Theory", 2005 ASME, IMECE-FPST No.79019)[1]. This paper introduces a new propeller driving system using the motor of the switch-mode hydraulic power supply for the underwater vehicle. And PFM (Pulse Frequency Modulation) control of high-speed switch-valves is applied to adjust the rotation speed of the propeller. The system has advantages over the widely used servo-valve valve-control system and pump-control system on the energy-weight ratio, anti-contamination performance and energy-saving capacity.

scholarly journals Clinical Application of the Pressure Forming for Metallic Denture Bases by the Use of Impulsive Hydraulic Pressure Produced by Impingement of a High Speed Projectile

1980 ◽  
Vol 24 (3) ◽  
pp. 442-450
Author(s):  
Takashi Nokubi ◽  
Yoshihiko Okuno ◽  
Tamotsu Yamaga ◽  
Yoshinobu Maeda ◽  
Yasunori Endo ◽  
...  
Keyword(s):  
Clinical Application ◽  
High Speed ◽  
Hydraulic Pressure

Research Status and Countermeasure of Temperature Rise of Hydraulic Dynamic and Static Bearing

2011 ◽  
Vol 291-294 ◽  
pp. 2291-2295
Author(s):  
Jian Fang Zhou ◽  
Jian Xi Yang
Keyword(s):  
Ball Mill ◽  
High Speed ◽  
Load Capacity ◽  
Hydraulic Pressure ◽  
Extreme Conditions ◽  
Research Strategies ◽  
Hydrostatic Bearing ◽  
Spindle Bearing ◽  
Increasing Temperature

Hydraulic dynamic and static bearing has the advantages of hydraulic pressure bearing and liquid hydrostatic bearing, with the peculiarities of higher load capacity, smallest oil film thickness, higher stiffness, and lower power and so on. It was suitable for not only high-speed precision spindle bearing but also low-speed heavy bearing. Because of the loading traits, ball mill will have a greater impact on the role of bearing, leading to the increasing temperature of bearing. The designers take many measures to reduce the temperature, but there are hardly any reports about mechanism of the increasing temperature. According to the study about the present situation and the research strategies of increasing temperature of dynamic and static bearing in the extreme conditions, this article explores the questions of the increasing temperature of dynamic and static bearing in the extreme conditions and the scarcity of this question at present, and proposes the mechanism and the research strategies of the questions of the increasing temperature of dynamic and static bearing of ball mill in the extreme conditions.

Numerical/Experimental Modelling of a Fuel Tank Impact

2005 ◽  
Author(s):  
Caroline M. Seddon ◽  
Moji Moatamedi ◽  
Wing Cheng
Keyword(s):  
Numerical Modelling ◽  
High Speed ◽  
Health And Safety ◽  
Fuel Tank ◽  
Hydraulic Pressure ◽  
Structural Behaviour ◽  
Fluid Structure ◽  
Experimental Modelling ◽  
Modelling Methodology ◽  
The Impact

High speed projectile impacts of fuel tanks can cause catastrophic failure. The complex fluid structure interactions produce structural behaviour that is often difficult to predict. This particular event was highlighted following the accident involving the Air France Concorde in July 2000. In this incident, accident investigations suggested that during the impact, penetration of the projectile didn’t occur, however, vibration of the skin coupled with excessive hydraulic pressure caused the tank to rupture outwards. The work reported details experimental and numerical analysis of a metallic rectangular fuel tank impacted by a high speed projectile, representative of the Concorde accident. The experiments were performed by Health and Safety Laboratory (HSL), in which the fuel tank was impacted at various projectile speeds. Numerical modelling of the experiments was undertaken, in which full fluid structure interaction was incorporated. Comparisons are made between measured and numerical accelerations at several points on the tank. The numerical results were consistent with the experiment, showing that the numerical modelling methodology was both valid and accurate.

A Hydraulic Pressure-Boost System Based on High-Speed On–Off Valves

2013 ◽  
Vol 18 (2) ◽  
pp. 733-743 ◽  
Author(s):  
Feng Wang ◽  
Linyi Gu ◽  
Ying Chen
Keyword(s):  
High Speed ◽  
Hydraulic Pressure

scholarly journals Spatter Formation and Splashing Induced Defects in Laser-Based Powder Bed Fusion of AlSi10Mg Alloy: A Novel Hydrodynamics Modelling with Empirical Testing

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2023
Author(s):  
Asif Ur Rehman ◽  
Muhammad Arif Mahmood ◽  
Peyman Ansari ◽  
Fatih Pitir ◽  
Metin Uymaz Salamci ◽  
...  
Keyword(s):  
High Speed ◽  
Laser Scanning ◽  
Scanning Speed ◽  
Operating Conditions ◽  
Powder Layer ◽  
Hydraulic Pressure ◽  
Powder Bed ◽  
Vapor Cloud ◽  
Laser Scanning Speed ◽  
Material Interaction

Powder spattering and splashing in the melt pool are common phenomena during Laser-based Powder Bed Fusion (LPBF) of metallic materials having high fluidity. For this purpose, analytical and computational fluid dynamics (CFD) models have been deduced for the LPBF of AlSi10Mg alloy. The single printed layer’s dimensions were estimated using primary operating conditions for the analytical model. In CFD modelling, the volume of fluid and discrete element modelling techniques were applied to illustrate the splashing and spatter phenomena, providing a novel hydrodynamics CFD model for LPBF of AlSi10Mg alloy. The computational results were compared with the experimental analyses. A trial-and-error method was used to propose an optimized set of parameters for the LPBF of AlSi10Mg alloy. Laser scanning speed, laser spot diameter and laser power were changed. On the other hand, the powder layer thickness and hatch distance were kept constant. Following on, 20 samples were fabricated using the LPBF process. The printed samples’ microstructures were used to select optimized parameters for achieving defect-free parts. It was found that the recoil pressure, vaporization, high-speed vapor cloud, Marangoni flow, hydraulic pressure and buoyancy are all controlled by the laser-material interaction time. As the laser-AlSi10Mg material interaction period progresses, the forces presented above become dominant. Splashing occurs due to a combination of increased recoil pressure, laser-material interaction time, higher material’s fluidity, vaporization, dominancy of Marangoni flow, high-speed vapor cloud, hydraulic pressure, buoyancy, and transformation of keyhole from J-shape to reverse triangle-shape that is a tongue-like protrusion in the keyhole. In the LPBF of AlSi10Mg alloy, only the conduction mode melt flow has been determined. For multi-layers printing of AlSi10Mg alloy, the optimum operating conditions are laser power = 140 W, laser spot diameter = 180 µm, laser scanning speed = 0.6 m/s, powder layer thickness = 50 µm and hatch distance = 112 µm. These conditions have been identified using sample microstructures.

Pressures on webs in wound rolls due to winding and contact

TAPPI Journal ◽  
2014 ◽  
Vol 13 (2) ◽  
pp. 41-50
Author(s):  
C. MOLLAMAHMUTOGLU ◽  
S. GANAPATHI ◽  
J.K. GOOD
Keyword(s):  
Contact Pressure ◽  
High Speed ◽  
Air Entrainment ◽  
Surface Velocity ◽  
Hydraulic Pressure ◽  
Local Dynamic ◽  
Compression Tests ◽  
Dead Weight ◽  
Wound Rolls ◽  
The Web

Paper, film, and metallic webs have designed surfaces. Process engineers design these surfaces to ensure they will coat or print correctly. In some cases, such as tissue, the manufactured surface is designed to provide softness. After the web is formed, care must be taken to maintain the web surface for the intended use or for subsequent processing. Web surfaces can be damaged by contact pressure, which is due to multiple sources. Tissues can suffer decreased loft and softness as a result of excessive pressure. Winding webs into rolls creates pressure on each web layer that varies with radial location. Almost all high speed winders must employ a nip roller in contact with the outer surface of the winding roll to prevent air entrainment. The nip roller, which may or may not be covered with an elastomer, induces local dynamic pressures where it contacts the winding roll that travel at the surface velocity of the winding roll. After rolls are wound, they can witness additional surface contact pressure. Often rolls are stored on flat surfaces and the dead weight of the roll induces contact pressure. In other cases, the roll may be moved by a clamp truck that employs hydraulic pressure to clamp and lift the wound roll. The objective of this paper is to demonstrate a method by which the total pressure in a web due to winding and to contact can be determined. Wound rolls of newsprint and polyester will be subjected to compression tests to verify the method.

The Modern Direct-Hydraulic System

1946 ◽  
Vol 154 (1) ◽  
pp. 178-208 ◽  
Author(s):  
F. H. Towler
Keyword(s):  
Hydraulic System ◽  
High Speed ◽  
Hydraulic Press ◽  
Hydraulic Pressure ◽  
Hydraulic Pump ◽  
Hydraulic Power ◽  
The Press ◽  
Hydraulic Accumulator ◽  
Work Done ◽  
Full Pressure

The first hydraulic press invented by Joseph Bramah in 1795 employed the direct-hydraulic system; i.e. hydraulic pressure was directly supplied to the press cylinder by a hydraulic pump and, therefore, the pressure exerted by the press ram was directly proportional to the pressure supplied by the pump, and the speed of the press ram was directly proportional to the delivery of the pump. Later developments in the use of hydraulic power resulted in the invention of the hydraulic accumulator to store liquid under pressure. With the accumulator system the speed and pressure exerted by the press ram are not controlled by the pump, and in fact they cannot be controlled with any precision; also there is considerable wastage of power when the press ram is operating at less than full pressure. The advent of the high-speed reciprocating ram pump has produced the modern direct-hydraulic system in which the press and pump form one self-contained unit. The power to drive the pump is in direct proportion to the work done by the press, and the speed and pressure exerted by the press ram can be precisely controlled. The author considers that a saving of at least 75 per cent in electric power can be made by conversion from the accumulator system to the direct-hydraulic system. Indicator diagrams are reproduced in the paper to show the saving in power which can be achieved by the direct-hydraulic system, and a comparison is made between the power consumption, in kilowatt-hours, of a direct-hydraulic cartridge-drawing press and a mechanical double-rack press doing the same operation. The paper includes a number of illustrations of direct-hydraulic presses, ranging from those of Bramah to present-day types.

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