Showing papers on "Piston published in 2008"

Gas distribution system and method for distributing process gas in a processing system

Abstract: An apparatus and related method for distributing process gas in a vapor deposition system is described. The gas distribution system includes a vertically movable piston within its plenum, and the movement of the piston controls the flow rate of process gas through the vapor distribution plate of the gas distribution system. The piston can be used to accommodate changes in processing parameters that affect flow characteristics and to create edge-enhanced, uniform, and center-enhanced profiles of deposited material on a substrate without the need to replace the vapor distribution plate.

Filament stretching rheometry and break-up behaviour of low viscosity polymer solutions and inkjet fluids

Abstract: This paper reports experimental observations on the way certain low viscosity Newtonian, polymer and inkjet fluids respond to filament stretching experiments that have been carried out using a variant of a multipass rheometer (MPR). A series of experiments were conducted where the opposing pistons of an MPR were used to provide controlled separation of two flat surfaces. Using 1.2 and 5.0 mm diameter pistons, a small quantity of test fluid was positioned between the pistons and the two pistons were moved apart at an equal and opposite velocity, thereby enabling optical interrogation of the central position of the filament that formed between the pistons faces. High speed photography followed the way the resulting fluid filament stretched and relaxed when the pistons movement had stopped. Different piston diameters, piston velocities and final piston separation were explored and the filament stretching and break-up was classified into regimes of behaviour. Approximate extensional viscosity parameters were obtained from the results. In some cases it was possible to correlate the filament stretching behaviour with the inkjet printing behaviour of a particular fluid.

Braking system for motor vehicles

Abstract: The invention relates to a braking system having a master cylinder (3), to which wheel braking cylinders can be connected, a first piston (11) coupled to a brake pedal (9) via a pressure rod (10) transmitting actuating forces, a second piston (12) that can be actuated by the first piston (11) and brought into a force-transmitting connection with a third piston (14), via which the master cylinder (3) is actuated, comprising at least one elastic element (42, 43) forming a pedal travel simulator that transmits a comfortable pedal feeling to the vehicle driver in the 'brake-by-wire' operating mode, and comprising means for coupling the movements of the first and second pistons, whereby a connection and disconnection of the pedal travel simulator occurs. In order to achieve the disconnection of the pedal travel simulator without any travel loss noticeable on the brake pedal, the invention provides that the means for coupling the movements of the first (11) and the second pistons (12) are automatically active in the event of a lack of pressure supply, and can be deactivated by the hydraulic pressure provided by the pressure supply device (2).

Regenerative shock absorber

Abstract: Regenerative shock absorber. A piston is disposed for reciprocating motion within a cylinder as a vehicle's suspension system deflects. Hydraulic fluid passes through an hydraulic motor to turn its shaft. The hydraulic motor shaft is connected to an electric generator to generate electricity. Flow characteristics of hydraulic circuits are selected to provide suspension system damping for appropriate wheel control.

A Novel Strategy of Efficiency Control for a Linear Compressor System Driven by a PWM Inverter

Abstract: Linear compressors with a free piston driven by a linear motor have attracted wide attention in cooling apparatuses such as refrigerators due to their high efficiency. The method of using triacs as a linear motor drive is not satisfactory for improving the efficiency of linear compressors. In this paper, the performance of linear compressors using a pulsewidth modulation inverter is investigated, with emphasis on the efficiency and power factor along with variations of both mechanical and electrical resonant frequencies. The strategy for improving the efficiency of the linear compressor is suggested by controlling the average value of the product of the piston stroke and motor current to 0. The performance of both the stroke and efficiency controls of the linear compressor is verified through experiments under various gas pressure conditions.

Administration apparatus for medical use

Abstract: An expansion/compression mechanism of a piston rod assembly is composed of a bush shaft, a first cylindrical piston rod that is screwed with the bush shaft, a second cylindrical piston rod that is screwed with the first piston rod, and a piston rod holding member for housing the bush shaft and these piston rods. Therefore, the piston rods move linearly in multiple stages.

Stirling cycle machine

Abstract: A Stirling cycle machine. The machine includes at least one rocking drive mechanism which includes: a rocking beam having a rocker pivot, at least one cylinder and at least one piston. The piston is housed within a respective cylinder and is capable of substantially linearly reciprocating within the respective cylinder. Also, the drive mechanism includes at least one coupling assembly having a proximal end and a distal end. The linear motion of the piston is converted to rotary motion of the rocking beam. Also, a crankcase housing the rocking beam and housing a first portion of the coupling assembly is included. The machine also includes a working space housing the at least one cylinder, the at least one piston and a second portion of the coupling assembly. An airlock is included between the workspace and the crankcase and a seal is included for sealing the workspace from the airlock and crankcase. A burner and burner control system is also included for heating the machine and controlling ignition and combustion in the burner.

Early Direct-Injection, Low-Temperature Combustion of Diesel Fuel in an Optical Engine Utilizing a 15-Hole, Dual-Row, Narrow-Included-Angle Nozzle

Abstract: Low-temperature combustion of diesel fuel was studied in a heavy-duty, single-cylinder optical engine employing a 15-hole, dual-row, narrow-included-angle nozzle (10 holes x 70/mD and 5 holes x 35/mD) with 103-/gmm-diameter orifices. This nozzle configuration provided the spray targeting necessary to contain the direct-injected diesel fuel within the piston bowl for injection timings as early as 70/mD before top dead center. Spray-visualization movies, acquired using a high-speed camera, show that impingement of liquid fuel on the piston surface can result when the in-cylinder temperature and density at the time of injection are sufficiently low. Seven single- and two-parameter sweeps around a 4.82-bar gross indicated mean effective pressure load point were performed to map the sensitivity of the combustion and emissions to variations in injection timing, injection pressure, equivalence ratio, simulated exhaust-gas recirculation, intake temperature, intake boost pressure, and load. High-speed movies of natural luminosity were acquired by viewing through a window in the cylinder wall and through a window in the piston to provide quasi-3D information about the combustion process. These movies revealed that advanced combustion phasing resulted in intense pool fires within the piston bowl, after the end of significant heat release. These pool fires are a result of fuel-filmsmore » created when the injected fuel impinged on the piston surface. The emissions results showed a strong correlation with pool-fire activity. Smoke and NO/dx emissions rose steadily as pool-fire intensity increased, whereas HC and CO showed a dramatic increase with near-zero pool-fire activity.« less

Drop-on-Demand Solder Droplet Jetting System for Fabricating Microstructure

Abstract: The novel drop-on-demand (DOD) solder droplet jetting system, which can be characterized as the non-heat affection of the piezoelectric actuator, the control mechanism of the piston head-to-nozzle distance, and disposable nozzle parts, is devised. This system consists of the piezoelectric actuator, insulator, piston head-to-nozzle distance control apparatus, pressure control unit, and furnace. For the modulation of the droplet size, the distance from piston head-to-nozzle exit can be controlled by using the piston head-to-nozzle distance control apparatus. The working temperature is improved by locating the piezoelectric actuator outside of the furnace and by inserting the insulation block between the print head and the actuator. From a practical point of view, the DOD solder droplet jetting system has a simple structure for easily interchangeable nozzle parts. We derived the equation of the ejected droplet volume as a function of design parameters and operating conditions. The prototype of the DOD solder droplet jetting system was fabricated and the performance was verified. The diameter, volume and velocity of the ejected solder droplet are around 65-150 mum, 140 pl-1.8 nl, and 2.8-4 m/s, respectively. We also experimented with the effect of varying the chamber pressure, piston head-to-nozzle distance, and operating frequency on the ejected droplet diameter and velocity. The high aspect ratio vertical columns and inclined columns were fabricated by using the DOD solder droplet jetting system.

Optimization study of the effects of bowl geometry, spray targeting, and swirl ratio for a heavy-duty diesel engine operated at low and high load:

Abstract: Optimization tools are used to recommend low-emission engine combustion chamber designs, spray targeting, and swirl ratio levels for a heavy-duty diesel engine operated at low load and high load. A non-dominated sorting genetic algorithm (NSGA II) was coupled with the KIVA computational fluid dynamics (CFD) code, as well as with an automated grid generation technique to conduct the multi-objective optimizations with goals of low emissions and improved fuel economy. The study identifies the aspects of the combustion and pollution formation that are affected by mixing, and offers guidance for better matching of the piston geometry with the spray plume geometry for enhanced mixing. By comparing the optimal results of low-load and high-load cases, the study reveals that different injection strategies and matching of the piston geometry with the spray plume are needed for different operating conditions. A non-parametric regression analysis tool was also used to post-process the optimized results in ord...

Tribology of compression ring-to-cylinder contact at reversal

Abstract: Piston ring-pack-to-cylinder contact accounts for one of the major sources of frictional losses in internal combustion engines. The regime of lubrication alters during the piston cycle because of the transient nature of applied load and kinematic contact conditions. Ring geometry, surface topography, and lubricant rheology also play an important role. The aim is to attain full fluid film lubrication, thus reducing friction because of boundary interactions. Therefore, accurate prediction of lubricant film thickness and pressure distribution constitutes the first step in a proper analysis of piston ring–cylinder conjunction. The creation of a gap through elastic deformation is sought in order to inhibit asperity tip interactions. The generated contact pressures in the lubricant film are due to combined entraining motion and squeeze film effect. The integrated pressure distribution balances the elastic force due to ring tension and the applied combustion pressure acting behind the ring. The article highlights a detailed analysis, which forms the basis for its future expansion to include the study of mixed regime of lubrication, which may be prevalent in some real engines

Improvements to electrically operable resuscitators

Abstract: The present invention relates to an electrically operable resuscitation device comprising a pump including a rigid cylinder including at least one gas inlet and at least one gas outlet, a piston to travel in said cylinder, and at least one valve, the or each valve configured to allow gas to be displaced into said cylinder through said at least one gas inlet during at least one of a first stroke direction and second stroke direction of said piston in said cylinder, and for allowing gas to displaced through said at least one gas outlet during an opposite of said at least one of the first stroke direction and second stroke direction of said piston in said cylinder; a motor, selected from one of a stepper motor and feedback motor and stepper motor with feedback and linear motor, operatively connected to said piston to move said piston in said cylinder; a patient interface in ducted fluid connection with said pump to receive gas via said at least one gas outlet and to deliver said gas to said patient.

Circulation control valve and associated method

Abstract: A circulation control valve includes an opening between the valve exterior and an interior passage, an internal closure device for permitting and preventing flow through the opening, a valve device initially preventing flow through the opening, and an internal chamber. The valve device opens upon application of a pressure differential between the passage and the exterior to thereby permit communication through the opening, and the closure device displaces upon a second pressure differential between the passage and the internal chamber to thereby prevent communication through the opening. Another valve includes first and second valve devices. Communication through the opening is permitted upon application of the first pressure differential to the first device, thereby unbalancing a first piston, and fluid communication through the opening is prevented upon application of the second pressure differential to the second device, thereby unbalancing a second piston having a greater piston area than the first piston.

Reciprocating machine & other devices

Abstract: The disclosure relates to reciprocating fluid working devices including internal combustion engines, compressors and pumps. A number of arrangements for pistons and cylinders of unconventional configuration are described, mostly intended for use in IC engines operating without cooling. Included are toroidal combustion or working chambers, some with fluid flow through the core of the toroid, a single piston reciprocating between a pair of working chambers, tensile valve actuation, tensile links between piston and crankshaft, energy absorbing piston-crank links, crankshafts supported on gas bearings, cylinders rotating in housings, injectors having components which reciprocate or rotate during fuel delivery. In some embodiments pistons mare rotate while reciprocating. High temperature exhaust emissions systems are described, including those containing filamentary material, as are procedures for reducing emissions during cold start by means of valves at reaction volume exit. Also disclosed are improved vehicles, aircraft, marine craft, transmissions and exhaust emission systems suited to the engines of the invention.

Hydraulic shock absorber

Abstract: In a hydraulic shock absorber, a damping force generating device is provided between a piston side oil chamber and a rod side oil chamber of a cylinder, and in a compression stroke, a compression side flow path for circulating oil in the piston side oil chamber of the cylinder through an outside flow path of the cylinder toward the rod side oil chamber is provided in the damping force generating device, while in an extension stroke, an extension side flow path for circulating the oil in the rod side oil chamber of the cylinder through the outside flow path of the cylinder toward the piston side oil chamber is provided in the damping force generating device.

Pressure, Flow, Force, and Torque Between the Barrel and Port Plate in an Axial Piston Pump

Abstract: This paper analyzes the pressure distribution, leakage, force, and torque between the barrel and the port plate of an axial piston pump. A detailed set of new equations is developed, which takes into account important parameters such as tilt, clearance and rotational speed, and timing groove. The pressure distribution is derived for different operating conditions, together with a complementary numerical analysis of the original differential equations, specifically written for this application and used to validate the theoretical solutions. An excellent agreement between the two approaches is shown, allowing an explicit analytical insight into barrel/port plate operating characteristics, including consideration of cavitation. The overall mean force and torques over the barrel are evaluated and show that the torque over the XX axis is much smaller than the torque over the YY axis, as deduced from other nonexplicit simulation approaches. A detailed dynamic analysis is then studied, and it is shown that the torque fluctuation over the YY axis is typically 8% of the torque total magnitude. Of particular novelty is the prediction of a double peak in each torque fluctuation resulting from the more exact modeling of the piston/port plate/timing groove pressure distribution characteristic during motion. A comparison between the temporal torque fluctuation pattern and another work shows a good qualitative agreement. Experimental and analytical results for the present study demonstrate that barrel dynamics do contain a component primarily directed by the torque dynamics.

Monoblock valveless opposing piston internal combustion engine

Abstract: The present invention provides an internal combustion engine that provides advantages of both typical 2-stroke engines and typical 4-stroke engines, but using a new design unlike either The present engine provides for use of pistons as means for opening and closing intake and exhaust ports disposed on cylinder walls It also provides two pistons per cylinder in an opposing configuration, such that one fuel explosion event causes motion of both pistons per cylinder, in opposite directions Each piston of a cylinder is connected to a separate crankshaft, which completes a single revolution about its axis per fuel explosion event in a cylinder In a single cycle of piston movement along the cylinder, a full cycle of ignition, exhaust, intake, and compression is achieved

Installation and methods for storing and methods for storing and restoring electrical energy using a piston-type gas compression and expansion unit

Abstract: The present invention relates to an installation and to methods for storing and returning electrical energy, comprising first and second lagged enclosures containing porous refractory material through which a gas is caused to flow by causing the gas to flow through first and second compression/expansion groups interposed in the pipe circuit between the top and bottom ends respectively of said first and second enclosures, each compression/expansion group comprising a piston moved in translation in a cylinder, each group operating in a different mode, either in compression mode or in expansion mode, one of the two compression/expansion groups receiving a gas at a temperature that is higher than the other group, such that in compression mode it is driven by an electric motor that consumes electrical energy for storage E 1 , and in a thermodynamic engine mode it drives an electricity generator enabling the electrical energy (E R ) to be returned. The electrical energy is stored in the form of heat within masses of refractory substances, and said stored potential thermal energy is returned in the form of electrical energy.

Perfect magnetic conductor Casimir piston in d + 1 dimensions

Abstract: Perfect magnetic conductor (PMC) boundary conditions are dual to the more familiar perfect electric conductor (PEC) conditions and can be viewed as the electromagnetic analog of the boundary conditions in the bag model for hadrons in QCD. Recent advances and requirements in communication technologies have attracted great interest in PMC's, and Casimir experiments involving structures that approximate PMC's may be carried out in the not-too-distant future. In this paper, we make a study of the zero-temperature PMC Casimir piston in d+1 dimensions. The PMC Casimir energy is explicitly evaluated by summing over p+1-dimensional Dirichlet energies where p ranges from 2 to d inclusively. We derive two exact d-dimensional expressions for the Casimir force on the piston and find that the force is negative (attractive) in all dimensions. Both expressions are applied to the case of 2+1 and 3+1 dimensions. A spin-off from our work is a contribution to the PEC literature: we obtain a useful alternative expression for the PEC Casimir piston in 3+1 dimensions and also evaluate the Casimir force per unit area on an infinite strip, a geometry of experimental interest.

Piston dispersive shock wave problem.

Abstract: The piston shock problem is a classical result of shock wave theory. In this work, the analogous dispersive shock wave (DSW) problem for a fluid described by the nonlinear Schrodinger equation is analyzed. Asymptotic solutions are calculated for a piston (step potential) moving with uniform speed into a dispersive fluid at rest. In contrast to the classical case, there is a bifurcation of shock behavior where, for large enough piston velocities, the DSW develops a periodic wave train in its wake with vacuum points and a maximum density that remains fixed as the piston velocity is increased further. These results have application to Bose-Einstein condensates and nonlinear optics.

Pyrotechnic actuator for retracting a piston

Abstract: A safety arrangement for a motor vehicle includes a pyrotechnic actuator for retracting a hinge pin of a vehicle hood. The pyrotechnic actuator includes a housing defining a longitudinal axis and further includes a first end defining an opening. The pyrotechnic actuator additionally includes a piston disposed in the housing for movement along the longitudinal axis between an extended position and a retracted position. The piston carries the pin. The pin at least partially extends from the housing in the extended position. The piston includes a base portion defining a combustion chamber. The pyrotechnic actuator further includes a pyrotechnic charge disposed in the combustion chamber for producing a combustion gas operative to move the piston from the extended position to the retracted position. The combustion chamber is defined by a thin walled member that is sealed to contain the ballistic event.

Added resistance of moonpools in calm water

Abstract: The additional ship resistance due to water oscillations in an open moonpool as constructed in drillships can be obtained through model tests. The oscillation has a dominant frequency and character, and the amplitude increases with forward speed. The resonant oscillation mode can be piston or sloshing. Recent measurements show that both types of oscillation can increase ship resistance to the same magnitude. The sloshing mode dominates in longer moonpools, while piston mode oscillations are dominant in shorter moonpools. Based on two model tests series carried out at Delft University of Technology, a resistance prediction model is constructed for piston type oscillations. The model was verified with a resistance measurement performed at MARIN in the past, showing fair agreement between the predicted and measured resistance increase.Copyright © 2008 by ASME