Showing papers on "Piston published in 2009"

Extendable cutting tools for use in a wellbore

Abstract: Embodiments of the present invention generally relate to extendable cutting tools for use in a wellbore. In one embodiment, a tool for use in a wellbore includes a tubular body having a bore therethrough, an opening through a wall thereof, and a connector at each longitudinal end thereof; and an arm. The arm is pivotally connected to a first piston and rotationally coupled to the body, is disposed in the opening in a retracted position, and is movable to an extended position where an outer surface of the arm extends outward past an outer surface of the body. The tool further includes the first piston. The first piston is disposed in the body bore, has a bore therethrough, and is operable to move the arm from the retracted position to the extended position in response to fluid pressure in the piston bore exceeding fluid pressure in the opening. The tool further includes a lock operable to retain the first piston in the retracted position; and a second piston operably coupled to the lock.

An Electrothermal Tip–Tilt–Piston Micromirror Based on Folded Dual S-Shaped Bimorphs

Abstract: This paper presents the design, optimization, fabrication, and test results of an electrothermally actuated tip-tilt-piston micromirror with a large optical aperture of 1 mm. The fabrication of the device is a combination of thin-film surface micromachining and bulk silicon micromachining based on silicon-on-insulator wafers. The device has 3-DOF of actuations, including rotations around two axes in the mirror plane, and out-of-plane piston actuation. The micromirror shows an optical scan range of plusmn30deg about both x- and y-axes and displaces 480 mum in the z-axis, all at dc voltages that are less than 8 V. Dynamic testing of the micromirror shows that the thermal response time of each actuator is about 10 ms. Resonant frequencies of the piston and rotation motion are 336 and 488 Hz, respectively. The unique structural design of the device ensures that there is no lateral shift for the piston motion and no rotation-axis shift for the rotation scanning. With the large tip-tilt-piston scan ranges and low driving voltage, this type of device is very suitable for biomedical imaging and laser beam steering applications.

Ventilator with piston-cylinder and buffer volume

Abstract: A mechanical ventilator is provided with a piston-cylinder for performing an air displacement function and a buffer volume and associated output valve for providing an air metering function. The piston-cylinder may comprise a reciprocating arrangement, in which compressed air is supplied to the buffer volume with each stroke of the piston.

A self- similar solution of a shock propagation in a mixture of a non-ideal gas and small solid particles

Abstract: Similarity solutions are obtained for unsteady, one-dimensional self-similar flow behind a strong shock wave, driven by a moving piston, in a dusty gas. The dusty gas is assumed to consist of a mixture of small solid particles and a non-ideal gas, in which solid particles are continuously distributed. It is assumed that the equilibrium flow-condition is maintained and variable energy input is continuously supplied by the piston. Solutions are obtained under both the isothermal and adiabatic conditions of the flow-field. The spherical case is worked out in detail to investigate to what extent the flow-field behind the shock is influenced by the non-idealness of the gas in the mixture as well as by the mass concentration of the solid particles, by the ratio of density of the solid particles to the initial density of the mixture and by the energy input due to moving piston. A comparison is also made between isothermal and adiabatic cases.

Kaluza-Klein models as pistons

Abstract: We consider the influence of extra dimensions on the force in Casimir pistons. Suitable analytical expressions are provided for the Casimir force in the range where the plate distance is small, and where it is large, compared to the size of the extra dimensions. We show that the Casimir force tends to move the center plate toward the closer wall; this result is true independently of the cross section of the piston and the geometry or topology of the additional Kaluza-Klein dimensions. The statement also remains true at finite temperature. In the limit where one wall of the piston is moved to infinity, the result for parallel plates is recovered. If only one chamber is considered, a criterion for the occurrence of Lukosz-type repulsion, as opposed to the occurrence of renormalization ambiguities, is given; we comment on why no repulsion has been noted in some previous cosmological calculations that consider only two plates.

Fluid logic tool for a subterranean well

Abstract: An operating tool uses programmed fluid logic provided by use of flow paths including pre-determined spaced ports and varying orifice sizes to provide discreet pressures and fluid flow rates upon pressure differential sensitive devices, such as a membrane or piston, in operative communication with an operative sleeve to manipulate one or more secondary tools, and/or to perform a service, such as, for example, acidzing or stimulation or injecting proppants within the well. The tool remains “immune” to internal well hydraulic or hydrostatic pressures, if desired, until the fluid logic is achieved. The fluid logic is adjustable for activation of tools sequentially by making changes in the port spacing and fluid relief profiles so that all tools can be actuated by a single geometry of fluid flow paths, or each tool can have its own unique fluid flow geometry so it becomes hydraulically coded.

Cylinder injection type spark ignition internal combustion engine

Abstract: PROBLEM TO BE SOLVED: To provide a cylinder injection type spark ignition internal combustion engine for efficiently strengthening a vertical swirl flow with injected fuel. SOLUTION: The cylinder injection type spark ignition internal combustion engine is provided for strengthening a vertical swirl flow in a cylinder with the penetrating force of fuel injected from a fuel injection valve 1 which injects fuel directly into the cylinder. The fuel injection valve injects fuel at a piston position where a center height H of a cylinder space approximately corresponds to a cylinder bore diameter D. COPYRIGHT: (C)2010,JPO&INPIT

Gas spring and gas damper assembly and method

Abstract: A gas spring and gas damper assembly includes a first end member, a second end member and a flexible wall that at least partially defines a first spring chamber therebetween. A damping chamber wall at least partially defines a damping chamber. A damper piston is received within the damping chamber and is operatively connected between the first and second end members and within the first spring chamber. A suspension system that includes a gas spring and gas damper assembly as well as a method of assembly are also included.

Reconciliation of excess 14C-constrained global CO2 piston velocity estimates

Abstract: Oceanic excess radiocarbon data is widely used as a constraint for air–sea gas exchange.However, recent estimates of the global mean piston velocity 〈k〉 from Naegler et al., Krakauer et al., Sweene...

Capacitive micromachined ultrasonic transducers with piston-shaped membranes: fabrication and experimental characterization

Abstract: Capacitive micromachined ultrasonic transducers (CMUTs) featuring piston-shaped membranes (piston CMUTs) were developed to improve device performance in terms of transmission efficiency, reception sensitivity, and fractional bandwidth (FBW). A piston CMUT has a relatively flat active moving surface whose membrane motion is closer to ideal piston-type motion compared with a CMUT with uniformly thick membranes (classical CMUT). Piston CMUTs with a more uniform surface displacement profile can achieve high output pressure with a relatively small electrode separation. The improved device capacitance and gap uniformity also enhance detection sensitivity. By adding a center mass to the membrane, a large ratio of second-order resonant frequency to first-order resonant frequency was achieved. This improved the FBW. Piston CMUTs featuring membranes of different geometric shapes were designed and fabricated using wafer bonding. Fabricating piston CMUTs is a more complex process than fabricating CMUTs with uniformly thick membranes. However, no yield loss was observed. These devices achieved ~100% improvement in transduction performance (transmission and reception) over classical CMUTs. For CMUTs with square and rectangular membranes, the FBW increased from ~110% to ~150% and from ~140% to ~175%, respectively, compared with classical CMUTs. The new devices produced a maximum output pressure exceeding 1 MPa at the transducer surface. Performance optimization using geometric membrane shape configurations was the same in both piston CMUTs and classical CMUTs.

Influence of Injection Timing and Piston Bowl Geometry on PCCI Combustion and Emissions

Abstract: Premixed Charge Compression Ignition (PCCI), a Low Temperature Combustion (LTC) strategy for diesel engines is of increasing interest due to its potential to simultaneously reduce soot and NOx emissions. However, the influence of mixture preparation on combustion phasing and heat release rate in LTC is not fully understood. In the present study, the influence of injection timing on mixture preparation, combustion and emissions in PCCI mode is investigated by experimental and computational methods. A sequential coupling approach of 3D CFD with a Stochastic Reactor Model (SRM) is used to simulate the PCCI engine. The SRM accounts for detailed chemical kinetics, convective heat transfer and turbulent micro-mixing. In this integrated approach, the temperature-equivalence ratio statistics obtained using KIVA 3V are mapped onto the stochastic particle ensemble used in the SRM. The coupling method proved to be advantageous in terms of computational expense and emission prediction capability, as compared with direct coupling of CFD and chemical kinetics. The results show that the fuel rich pockets in the late injection timing are desirable for triggering auto-ignition and advancing the combustion phasing. Furthermore, the model is utilised to study the impact of combustion chamber design (open bowl, vertical side wall bowl and re-entry bowl) on PCCI combustion and emissions. The piston bowl geometry was observed to influence the in-cylinder mixing and the pollutant formation for the conditions studied. INTRODUCTION Low Temperature Combustion (LTC) modes such as Homogeneous or Premixed Charge Compression Ignition (HCCI/PCCI) are receiving increased attention due to their potential for simultaneously reducing soot and NOx emissions from Direct Injection (DI) diesel engines. PCCI mode involves premixed combustion of a highly diluted or lean mixture and the combustion process is primarily controlled by the chemical kinetics. Thus, the control of ignition timing and burning rate in PCCI combustion is fundamentally more challenging than in a conventional compression ignition DI diesel engine governed mainly by physical processes such as fuel-air mixing. Furthermore, for the cases where the airfuel charge is often not purely homogeneous, the influence of fuel-air mixing on combustion also needs to be taken into account. In addition to experimental studies, a variety of computational modelling approaches based on multidimensional computational fluid dynamics (CFD) have also been applied to investigate early direct injection PCCI combustion. The detailed chemical kinetics and the flow description in PCCI mode are relatively decoupled, when compared to conventional diesel combustion. This fact has been exploited by sequential solvers based on CFD and multi-zone combustion models [1-3]. In a multi-zone approach, the computational cells having similar temperature and composition histories are grouped into a relatively small number of zones (~10). The chemical kinetics solver is applied to each zone, assumed as a well stirred reactor. Flowers et al. [2] modified the multi-zone model to This is Computational Modelling Group's latest version of the paper. For the published version please refer to http://www.sae.org/technical/papers/2009-01-1102

Power losses in the lubricating gap between cylinder block and valve plate of swash plate type axial piston machines

Abstract: The lubricating gaps are the primary source of energy dissipation in piston machines. The paper presents results of a simulation study that investigates the effect that a wave-like micro surface shape variation applied to the valve plate gap surface has on power loss in the cylinder block-valve plate interface. Special attention is given to the relation between gap height, operating parameters, surface design and power loss. The effect of waved surface amplitude and frequency is also studied. Results indicate that power loss in the cylinder block-valve plate interface can be reduced by over 50% on account of the waved surface compared to the standard cylinder block-valve plate interface design. The effect of the waved surface is most significant at low operating pressures. A special in-house code has been used for this research study. The simulation model covers fluid-structure interaction and micro motion of the cylinder block resulting from oscillating piston forces. Details of the model are exp...

Regenerative shock absorber system

Abstract: A regenerative shock absorber that include a housing and a piston that moves at least partially through the housing when the shock is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor, in turn, drives an electric generator that produced electric energy. The electric energy may be provided to a vehicle, among other things. The regenerative shock absorber may also provide ride performance that comparable to or exceeds that of conventional shock absorbers.

Dynamic Modeling of a Regenerator for the Control-Based Design of Free-Piston Stirling Engines

Abstract: This paper describes a new approach to modeling and designing free-piston Stirling engines with the goal of building a working prototype. The Stirling cycle is recast as a dynamic system where control design tools and techniques can be applied to determine optimal manufacturable parameters for the engine. A simplified state-space analysis exhibits the merits of this perspective by revealing a link between pole locations and power production. The results of this analysis suggest the potential of a new, compact free-piston Stirling engine configuration using elastomeric pistons. An engine of this type is described analytically with a physics-based, high-order, lumped- parameter, dynamic model. To support one component of the model, a regenerative heat exchanger is described using a lumped parameter, nth-order model generalizable to an arbitrary number of sections within the regenerator dependent on its physical aspect ratio. Finally, the heat exchanger model is experimentally verified.

A rolling piston-type two-phase expander in the transcritical CO2 cycle.

Abstract: Although the application of the CO2 cycle to refrigeration and air conditioning can be good for the environment, it can also be inefficient. To improve the efficiency of the cycle, new devices must be developed, such as a CO2 rolling piston-type expander that can take the place of the throttling valve in the system to recover power during the expansion process. The parameters of the rolling piston-type expander (e.g., mass flow rate and the volume of the cylinder, the suction port, and the discharge port) were analyzed and designed. The experimental prototype was constructed and tested. The expander replaced the throttling valve in the experimental Transcritical CO2 water-source heat pump. The experimental results showed that the suction control system and the expander could work normally. The expander, having measured isentropic efficiency up to 58.7%, increased the cooling coefficient of performance (COP) up to at least 10% at tested conditions.

A reciprocating piston mechanism

Abstract: A reciprocating piston mechanism (1) comprises a crankcase (15) and a crankshaft (2) which has at least a crankpin (4). The crankshaft (2) is supported by the crankcase (15) and rotatable with respect thereto about a crankshaft axis (5). The mechanism further comprises at least a connecting rod (9) including a big end (8) and a small end (10), a piston (11) which is rotatably connected to the small end (10), and a crank member (6) which is rotatably mounted on the crankpin (4). The crank member (6) comprises at least a bearing portion (7) and has an outer circumferential wall which bears the big end (8) of the connecting rod (9) such that the connecting rod (9) is rotatably mounted on the bearing portion (7) of the crank member (6) via the big end (8). The crank member (6) is provided with a crank member gear (12). The crank member gear (12) is an external gear, which meshes with at least an intermediate gear (13). The intermediate gear (13) is an external gear, which also meshes with an auxiliary gear (14). The auxiliary gear (14) is an external gear, which is fixed to an auxiliary shaft (16) that extends concentrically through the crankshaft (2). The crankshaft (2) and the auxiliary shaft (16) are rotatable with respect to each other.

Piston mode acoustic wave device and method providing a high coupling factor

Abstract: An interdigital transducer includes an edge gap length between ends of electrodes and the opposing busbar increased sufficiently for reducing or even eliminating tunneling effects through the gap. As a result, a wave velocity of the acoustic wave within the longitudinally extending edge regions is less than the wave velocity within the transducer center region, and the wave velocity within the opposing gap regions is greater than a velocity in the transducer center region, thus an essentially flat propagation mode results within the aperture of the transducer. A SAW transducer or a SAW resonator on a high coupling substrate will thus guide the energy in the transducer region without a need for apodization. Higher equivalent coupling factors as well as lower losses are obtained.

Shock absorbing device

Abstract: A shock absorbing device includes a cylinder. A partition wall member is inserted into the cylinder to be free to slide and partitions an interior of the cylinder into two operating chambers. A passage connects the two operating chambers. A free piston is inserted into a pressure chamber to be free to slide and partitions the pressure chamber into one chamber that communicates with one operating chamber via a one side flow passage and another chamber that communicates with the other operating chamber via another side flow passage. A spring element generates a biasing force for suppressing displacement of the free piston relative to the pressure chamber. One or both of a bypass flow passage that connects the other chamber and the one operating chamber and a bypass flow passage that connects the one chamber and the other operating chamber is provided. A relief valve is provided in the bypass flow passage.

Design, test and model of a hybrid magnetostrictive hydraulic actuator

Abstract: The basic operation of hybrid hydraulic actuators involves high frequency bi-directional operation of an active material that is converted to uni-directional motion of hydraulic fluid using valves. A hybrid actuator was developed using magnetostrictive material Terfenol-D as the driving element and hydraulic oil as the working fluid. Two different lengths of Terfenol-D rod, 51 and 102 mm, with the same diameter, 12.7 mm, were used. Tests with no load and with load were carried out to measure the performance for uni-directional motion of the output piston at different pumping frequencies. The maximum no-load flow rates were 24.8 cm3 s−1 and 22.7 cm3 s−1 with the 51 mm and 102 mm long rods respectively, and the peaks were noted around 325 Hz pumping frequency. The blocked force of the actuator was close to 89 N in both cases. A key observation was that, at these high pumping frequencies, the inertial effects of the fluid mass dominate over the viscous effects and the problem becomes unsteady in nature. In this study, we also develop a mathematical model of the hydraulic hybrid actuator in the time domain to show the basic operational principle under varying conditions and to capture phenomena affecting system performance. Governing equations for the pumping piston and output shaft were obtained from force equilibrium considerations, while compressibility of the working fluid was taken into account by incorporating the bulk modulus. Fluid inertia was represented by a lumped parameter approach to the transmission line model, giving rise to strongly coupled ordinary differential equations. The model was then used to calculate the no-load velocities of the actuator at different pumping frequencies and simulation results were compared with experimental data for model validation.

Hearing results using the SMart piston prosthesis.

Abstract: Objective:SMart, a newly introduced piston prosthesis for stapedotomy, is a nitinol-based, heat-activated, self-crimping prosthesis. We review our hearing results and postoperative complications using this self-crimped piston prosthesis and compare them with those obtained using stainless steel or p

Suck back valve

Abstract: PROBLEM TO BE SOLVED: To provide a suck back valve preventing dripping from an end of a pipe, and dispensing with adjustment of timing of valve closure and suck back operation SOLUTION: The suck back valve comprises: a main body 1; a first valve element 29 brought into press-contact with or separated from a valve seat part 23; a second valve element 37 changing a capacity of a second valve chamber 21 to suck back fluid; a first movable member 6 retaining the first valve element 29; a second movable member 8 connected with the first movable member 6 by a connecting rod, and positioned above the second valve chamber 21; and a piston 7 having a rod part 43 connected with the second valve element 37 at a lower end thereof The first movable member 6 and the second movable member 8 connected by the connecting rod are energized upward with a predetermined force, a piston 7 can be interlocked with the second movable member 8 while the collar part 42 is abutted with the second movable member 8, and the piston moves up and down collar part 42 The first valve element 29 abuts on or separates from the valve seat part 23 to open/close the valve, and the collar part 42 is separated from the second movable member 8 to suck back the fluid COPYRIGHT: (C)2009,JPO&INPIT