Showing papers on "Piston published in 1981"

Review of transient field theory for a baffled planar piston

Abstract: The theoretical approaches which have been used to study the velocity potential and pressure fields radiated by a planar piston source vibrating in an infinite rigid baffle are broadly reviewed and discussed with emphasis on the basic mathematical methods employed. Attention is focused on those aspects of piston theory directly related to the point or spatially averaged transient field of a pulsed piston radiator. Studies of the nonuniformly vibrating piston are also reviewed. Much of this material has not been previously compared, so where possible common origins and general relationships are stressed.

Inflating and deflating device for vascular dilating catheter assembly

Abstract: Inflating and deflating device adapted to be used by a human hand. It comprises a housing and a syringe carried by the housing. The syringe comprises a syringe body having an outlet through which liquid can pass and a piston slidably mounted in the syringe body and forming a sealing engagement with the body. A piston rod is secured to the piston and extends out of the body. A tubular member is provided. A connector means connects the tubular member to the outlet of the syringe body. A handle is carried by the housing and is secured to the syringe for causing relative movement between the piston and the syringe body. The handle means includes first and second portions movable with respect to each other. The first portion is secured to one of said piston rod or said syringe body and the other said portions are secured to one of the other of said piston rod and said syringe body. The first portion is of a size so as to be adapted to being engaged by all of the fingers of the hand and the second portion is adapted to be engaged by the palm of the hand during the time that the fingers of the hand are engaging the first portion whereby a force to cause relative movement between the piston and the syringe body can be created by that hand.

Automated liquid dispenser control

Abstract: A servo controlled actuator for an automated liquid dispenser for dispensing reagents or diluting samples with reagent automatically in accord with a programmed local microprocessor or remote computer control. The dispenser has at least one reciprocable syringe, valving for it and a syringe actuator driven by a hybrid servo control. The actuator includes a bi-directional variable speed motor and an encoder developing a pulse train which in number is representative of the position of the syringe piston and in repetition rate is representative of piston velocity. A microprocessor controls the piston stroke from the pulse train by comparison to a memory-stored count and controls piston velocity in predetermined relation to the terminal end of piston travel.

Fluid pressure cylinder

Abstract: A fluid power cylinder having a cylinder (14) with an elongated slot (15) extending generally parallel to the longitudinal axis of the cylinder (14), a reciprocally movable piston (24) and a strip sealing means (13, 17) for successively sealing the slot (15) during movement of the piston (24). The sealing member (13,17) is of a laminated construction and is constructed partially of a magnetized rubber-like material for magnetic attraction to the cylinder wall adjacent the slot (15). The sealing member (13, 17) also includes beveled edges for engagement with beveled edges adjacent the slot (15).

Downhole chemical cutting tool

Abstract: A downhole chemical cutting tool having an improved cutting section. The tool comprises an elongated tool body adapted for insertion into a well bore and includes anchoring means actuatable between a deployed position in response to the application of fluid pressure and a retracted position in response to the release of such pressure. The tool further includes a chemical section and a cutting section located in front of the chemical section. The cutting section has a longitudinally extending bore which is in fluid communication with the chemical section at the rear of the cutting section and in fluid communication with the exterior of the tool body at the front of the cutting section. The cutting section is provided with one or more cutting ports through which the cutting fluid passes when the tool is fired. A piston is slidably disposed in the bore of the cutting section at a location between the ports and the chemical section. When the tool is fired, the fluid pressure developed sets the anchoring means and forces the piston forward, exposing the port to the cutting fluid flowing into the bore from the chemical section. The tool further comprises means in the cutting section in front of the port to receive the piston upon the application of fluid pressure in the tool to lock the piston in place at a location in front of the cutting port. The locking means may take the form of a reduced section in the cutting tool bore which is adapted to receive a portion of the piston in a swedged relationship.

Self contained injection system

Abstract: Method and apparatus for injecting fluids into patients at a controlled rate from an ampule containing the injecting fluid with a sliding piston therein to force the fluid from the ampule into the patient using a drive system which incrementally and successively advances the piston in the ampule to meter the fluid into the patient.

Power plant and process utilizing gravitational force

Abstract: Power plant and processes for converting gas expanding energy sources into useful forms. A piston (13, 13a, 13c, 13d and 13e) containing a magnet (38) and able to free fall within an enclosed cylinder (12, 12a, 12c, 12d and 12c), having a center portion (15) surrounded by an induction coil (19) is repeatedly impelled upwards, thereby inducing an alternating electric current in the coil (19). In a preferred mode, a mixture of fuel and air is ignited beneath the piston (13), and in response to the piston's upward motion, compressed air is pumped into a reservoir (14). In a first alternative mode, fuel is ignited at both ends of the cylinder, in a second, the heat of concentrated solar energy is directed onto a liquid (47) in the bottom of the cylinder (12c), in a third, hydrogen is burned below the piston (13d) to create heat which vaporizes water, and in a fourth, hydrogen is burned at both ends of the cylinder (12e).

Piston actuated, pilot valve operated breathing regulator

Abstract: A breathing regulator includes a pressure-responsive piston which acts directly on a valve seat to open a pressurized gas pilot valve during inhalation. The same piston provides an outlet for exhalation. The piston is moved to open the pilot valve by inhalation suction. A one-way valve automatically blocks the exhalation path during inhalation. The outlet for the pressurized gas provides an injector nozzle effect to reduce the effort required to actuate the valve during inhalation. The preferred embodiment of the invention incorporates the regulator in a resuscitator or respirator for medical applications. In this embodiment, a mechanism is included for controlling the amount of inhalation back pressure in the patient's air passages which will close the pressurized gas valve and open the exhaust passage in the regulator. This mechanism includes an adjustable spring-loaded pressure plate on the external side of the piston. The inhalation pressure adjusting mechanism also provides for positive end expiratory pressure. In another embodiment, the basic regulator is adapted for use as a breathing regulator for high altitude aviation. In this embodiment, the invention includes aneroid bellows which close an ambient air inlet when a predetermined altitude is reached, so that breathing is exclusively from a pressurized gas source. The aviation embodiment also provides for pressurized breathing.

Finite-time thermodynamics: Engine performance improved by optimized piston motion.

Abstract: The methods of finite-time thermodynamics are used to find the optimal time path of an Otto cycle with friction and heat leakage. Optimality is defined by maximization of the work per cycle; the system is constrained to operate at a fixed frequency, so the maximum power is obtained. The result is an improvement of about 10% in the effectiveness (second-law efficiency) of a conventional near-sinusoidal engine.

Compressor having functions of discharge interruption and discharge control of pressurized gas

Abstract: A compressor is provided which has a housing formed with a volume control chamber located in the vicinity of the discharge port and within which a valve is mounted, a first port communicating the volume control chamber with a pumping chamber defined within the housing, and a second port communicating the volume control chamber with the suction port. The valve is disposed so as to open selectively the first port alone or both the first port and the second port, to thereby make it possible to control the discharge rate of pressurized gas or interrupt discharge of same without interruption of driving of the gas pressurizing member of the compressor for compression of gas such as a rotor or a piston.

Integral hydraulic blocking and relief valve

Abstract: An integral hydraulic blocking and relief valve (12) for use in an aircraft night power actuator (60) includes a unique stepped piston assembly (PA and PB) referenced to return or relieve system pressure (P) at the same, predetermined level, independent of any influence due to the system pressure (P), and control valve means (20) for controlling hydraulic system fluid to the hydraulic blocking and relief valve (12) for actuating the night power actuator (60).

Hydraulically operated actuator

Abstract: A hydraulically operated actuator employs multiple metal-to-metal static seals to isolate the hydraulic fluid and to isolate the actuator from surrounding contaminating (ambient) fluids. A housing contains at least two linearly spaced apart chambers. A piston reciprocates from a retracted position to an extended position (power stroke) and from the extended position to the retracted position (return stroke) in one of the chambers (hydraulic chamber). The hydraulic chamber is separated by the piston into two sections, one of which contains high pressure hydraulic fluid and the other of which contains low pressure hydraulic fluid. A first static metal seal ring unit is designed to seal first at the completion of the power stroke of the piston to isolate the low pressure hydraulic fluid section from external contaminating fluids which may be at a higher pressure. A second static metal seal ring unit is designed to seal at the completion of the return stroke of the piston also to isolate the low pressure section from external contaminating fluids. Power for the return stroke is primarily supplied by springs, with biasing pressure from the external environment providing a lesser contribution. A third static metal seal ring unit may be employed to obtain a simultaneous seal with the first metal seal ring unit to isolate the high pressure section from the low pressure section at the completion of the power stroke of the piston.

Two-piece piston assembly

Abstract: A two-piece piston assembly comprises an upper portion or a ring carrier part that may be made of malleable iron, cast iron, or a similar iron, and a lower portion or cross-head part, referred to as a skirt, that may be made of aluminum or an alloy thereof. The assembly is configured to increase the contact of cooling liquid with the underside of the crown and eliminate problems accompanying undue heating in this area of the piston. The cocktail-shaker action of the two-piece piston assembly is employed to enhance the cooling effect. A separate cup-like device is secured around the outside of the lower end of the crown member of the piston and is thus positioned between the upper and lower portions of the piston to retain the oil and effectively deliver it to the underside of the crown.

Delivery of adjustable quantities of materials

Abstract: A delivery device and method making use of a plunger which can be controllable reciprocated within a housing to regulate the amount of material expelled from the housing. The plunger includes an adjustable stop collar which can be adjustably positioned, preferably by depressing the sides of the collar. In addition, a piston within the housing is sealably releasable from the plunger.

Muffler system for refrigeration compressor

Abstract: A hermetic reciprocating piston refrigeration compressor has a high efficiency muffler system. The suction muffler has an inlet adjacent the refrigerant return line and is made of an insulating material. It is mounted on a pair of suction tubes secured to the cylinder head and extending into the interior of the muffler. A discharge muffler system includes a pair of large muffler chambers formed partially in a cylinder block and connected by an external transfer tube. A large straight passage connects the discharge plenum in the cylinder head with one muffler chamber, while a discharge line extends from the other muffler chamber to the exterior of the compressor casing.

Wave activated power generation system

Abstract: A wave activated power generation system of the float type comprising at least one piston-cylinder device having an anchored cylinder and a piston slidable in the cylinder and cooperating with the cylinder to form a pumping chamber above the piston and a low pressure chamber below the piston. The cylinder has an intake port and an exhaust port both formed at an upper portion thereof to communicate with the pumping chamber and each provided with a check valve. A float is connected through a cable to the piston of the piston-cylinder device. A pair of fluid storages are connected to the intake port and the exhaust port of the pumping chamber, respectively. A waterwheel generator is driven by the fluid flowing from one of the fluid storages to another. A pressure regulating device is connected to the low pressure chamber so as to maintain the low pressure chamber at a pressure lower than the pressure in the pumping chamber, the difference in pressure ceaselessly applying a downward force on the piston to keep the cable in a tensed condition.

Mud saver valve

Abstract: Disclosed is a mud saver valve which includes a tubular body connectable between a kelly and a drill string. An annular seat ring having a central opening is mounted within the body. A piston is axially movably mounted within the body for engagement with the seat ring. The piston includes a bore substantially coaxially aligned with the central opening and a flange that extends radially outwardly from the piston to slidingly engage the interior of the body. The piston has a plurality of ports above the piston to communicate the exterior of the piston with the bore. A plug is removably mounted in the piston. The plug includes a shear ring removably inserted in the bore and a spear axially movably mounted in the shear ring. The plug is movable between a first position wherein the spear sealingly engages the shear ring in a second position that allows fluid to flow upwardly between the spear and the shear ring. A spring is provided to urge the piston into engagement with the seat ring.

Nonlinear equations of acoustics, with application to parametric acoustic arrays

Abstract: The propagation and interaction of finite amplitude sound waves produced by a baffled piston source in a thermoviscous fluid are considered. Basic equations are derived and their ranges of validity established. This is used to relate some earlier works by others on nonlinear model equations in acoustics. Applications are made to the theory of parametric acoustic arrays, where the effects of nonlinear attenuation are discussed.

Hydraulically operated impact device

Abstract: In a hydraulic rock drill there is a hydraulic so called recoil damper that damps the reflected shock waves that propagates from the rock backwardly through the drill stem. The damper comprises a support piston (68) slidably in a cylinder so that a pressure chamber (20) is formed in which the support piston has a piston area. Narrow clearances (75,76) between the support (68) and its cylinder form leak passages and these leak passages are coupled in series with an orifice restrictor (84) to a sump. The pressure peaks in the pressure chamber do not reach sealing rings located at the outer portions of the clearances.

Piezoelectric fluid injector

Abstract: Method and apparatus for injecting fluids into patients at a controlled rate from an ampule containing the injecting fluid with a sliding piston therein to force the fluid from the ampule into the patient using a drive system which incrementally and successively advances the piston in the ampule to meter the fluid into the patient.

Cam controlled reciprocating piston device

Abstract: A unique reciprocating piston device that uses one or more special cams and yokes to replace the functions normally provided by crankpins and connecting rods. The cams have noncircular finite jerk lift surfaces which provide continuous positive positioning of the yokes and pistons. Various cams can be configured to overcome the performance limitations imposed by crank and rod controlled pistons for a wide variety of engines and pumps. Preferred embodiments of this invention create a flexible, reliable, efficient and smooth running device for compressing, expanding and transferring fluids. In one specific application, an internal combustion engine is designed such that its pistons spend a greater portion of time near the top and bottom of each stroke than is possible with a crankshaft type engine.

Blood extracting and centrifuging device

Abstract: A blood extracting and centrifuging device has a cylindrical body 1 with front and rear ends 2, 3. The front end is adapted to receive a removable cannula 4 and a piston 8 is sealingly movable within the cylindrical body 1. A piston rod 9 attached to the piston 8 extends through a bore 10 at the rear end of the cylindrical body and is used to retract the piston, from an advanced position adjacent the front end to a retracted position adjacent the rear end, whereby to generate a vacuum in the cylindrical body 1 for extracting blood via the cannula 4. Securing means in the form of an annular retaining projection 22 on one of the piston 8 and the piston rod and an annular lip 24 at the rear end of the cylindrical body 1 are provided to secure the piston to the cylindrical body in its retracted position. After a blood sample has been taken the piston rod 9 can be removed and the cylindrical body 1 inserted directly in a centrifuge without the need to transfer the blood to a centrifuging vessel.

Wabbler plate engine mechanisms

Abstract: The invention relates to wabbler plate engine mechanisms. One such mechanism has a wabbler plate rotatably mounted on a wabbler carrier which is in turn inclinably mounted on a crankshaft in a crankcase. The wabbler plate has a plurality of arms which are coupled to pistons slidably mounted in cylinders arranged around the axis of the crankshaft. As the crankshaft rotates, each arm oscillates laterally relative to its respective piston and a stabilizer mechanism comprising ball races on the wabbler plate and a ball carrier on the crankcase, is included to prevent the oscillations from unbalancing the mechanism. This construction is quite satisfactory but is not readily adaptable to provide for variable displacement. Attempts have been made to incorporate this facility, but a successful solution has not yet been found. In order to provide a variable displacement facility in an engine mechanism of the above kind, the present invention incorporates means for shifting the rotational axis of the wabbler plate along the axis of the crankshaft, and the ball carrier parallel thereto, while simultaneously altering the angle between the crankshaft axis and the wabbler carrier to vary the stroke of the mechanism. The invention also provides for the effective lengths of the ball races to be variable to accommodate the alternation of said angle.

Apparatus for producing a rotary speed-dependent control pressure

Abstract: The invention relates to a device for producing a control pressure which corresponds to a rotary speed imparted to a shaft of a pump which is a part of the device. The device includes a measuring orifice formed by a fixed throttle and a control orifice formed by piston arrangement operating as a controlled throttle. The controlled throttle is responsive to oppositely acting pressures from opposite sides of the fixed throttle. The controlled throttle is in series with a fixed discharge throttle and the control pressure is tapped from between the controlled throttle and the discharge throttle.

Compact hydraulic drive for die closing unit of injection molding machine

Abstract: A hydraulic actuator assembly for a push-type die closing unit of an injection molding machine capable of producing rapid die opening and closing movements with a small volume of pressurized fluid and an elevated die closing pressure in the closed die position, the assembly comprising a central power cylinder with a selectively bypassable power piston and two parallel, diametrally oppositely arranged single-acting travel cylinders. The low-pressure space on the forward side of the power piston is open to the pressure spaces of the two travel cylinders, and the total effective area of these pressure spaces is larger, by a relatively small amount, than the area of the high-pressure space to the rear of the power piston, said small amount determining the fluid volume necessary for the opening travel. A stationary plunger cooperates with a central bore in the rear portion of the power piston rod to produce a small pressure space for the closing travel. An elevated die closing pressure is obtained by pressurizing the high-pressure space of the power piston and the plunger pressure space, with the power piston bypass closed.

Oleopneumatic suspension with variable throttle orifices, especially for aircraft landing gear

Abstract: An oleopneumatic suspension with variable throttle orifices, particularly for aircraft landing gear comprising a rod (1) enclosing a pneumatic spring (2) and being fixed with respect to a piston (4) sliding in a cylinder (3), two valves (6) and (7) with permanent throttle orifices, the valve (6), which is of greater cross-section, throttling in the compression phase and the valve (7), which is of lesser cross-section, throttling in the extension phase, the suspension comprising in addition a throttle device, the section of whose orifice varies in dependence on the position and the direction of displacement of the piston (4) in the cylinder (3) so that over a given distance around a predetermined equilibrium position the orifices ensuring throttling in the compression and extension phases are of cross-sections respectively greater than the corresponding orifices over the remainder of the distance covered by the piston (4) in the cylinder (3). While primarily for use in connection with landing gear or support bogies of aircraft, the suspension is also suitable for land vehicles or for testing.

Internal combustion driven pumping system and variable torque transmission

Abstract: An internal combustion driven fluid pumping apparatus for accumulating fluid pressure to be applied against a load includes a two-stroke combustion cylinder having a piston drivingly connected to a piston of a linearly disposed compression cylinder, which is in turn connected by a fluid conduit to a pressure accumulator. The accumulator is operatively connected to the compression cylinder such that the frequency of cycles of the combustion cylinder varies with the changes in the demand of the load upon the fluid pressure stored in the accumulator, and such that the speed of the pistons in each individual stroke is substantially constant. To begin each cycle, fluid is forced into the compression cylinder at a pressure less than the pressure of fluid in the accumulator, but sufficient to compress and ignite combustible gases in the combustion cylinder. A transmission system is also provided wherein a variable volume hydraulic pump including a pump shaft drivingly connected to the load is driven by the shaft of a hydraulic motor, which is in turn driven by a high pressure fluid source. Fluid conduits connect the low pressure output of the motor to the low pressure input of the pump, and the high pressure output of the pump to the high pressure input of the motor, or to an accumulator. The displacement of the pump can be varied to vary the torque transmitted to the load, while maintaining the torque of the motor at a substantially constant rate.