Abstract: An electrohydraulic apparatus (1) transmitting motion from one location to another utilizes a pair of linear motor assemblies (111, 113) to impart motion to respective hydraulic means (115, 117) providing continuous fluid flow performing work at a work station (119), hereby providing an improved electrohydraulic apparatus and method for performing work.

Abstract: A free piston type compressor includes a piston slidably fitted within a cylinder. A compression chamber is defined in the cylinder on one side of the piston, and a balance chamber is defined in the cylinder on the other side of the piston. A piston rod is connected to the piston and axially extends out of the cylinder through the balance chamber. A valve mechanism includes a suction valve, a discharge valve, and a valve plate, and is disposed on the end portion of the cylinder that faces the compression chamber. Since the piston rod extends out of the cylinder without passing through the compression chamber, the seal between the cylinder and the piston rod is not subjected to the high pressure working fluid, and the volumetric efficiency of the compressor is increased by reducing the dead clearance in the compression chamber.

Abstract: This invention relates to linear motor compressors which operate without the use of oil. Such structures of this type, generally, provide a highly reliable oil-free compressor for use with cryogenic refrigeration equipment so as to attain unattended, continuous operation without maintenance over extended periods of time.

Abstract: A new and improved linear motor-pump assembly and method of using it for downhole use. The assembly includes a cartridge unit with a linear motor attached threadably between a discharge housing assembly adapted to be secured removably to a cable for hoisting the cartridge unit through the production tubing of a well and a suction housing assembly for facilitating the pumping of well fluids from a downhole well. The linear motor includes a mover adapted to engage threadably a stop valve for permitting one-way flow of fluid through the mover and into the discharge housing for discharge into the production tubing. For increased pumping efficiency, the suction housing and check valve are replaceable with a lifting pump and piston respectively. Thus, the assembly is usable in both shallow and deep wells.

Abstract: An air breezing pump designed to supply air for biasing the vibrator of a speaker by providing a conventional speaker with an air inlet valve and an air outlet valve on its vibrating medium, and thereby excluding existing ducts from the enclosure of the speaker assembly.

Abstract: An electromagnetic reciprocating pump comprising of a closed-type casing provided with a cylinder in front thereof, a main shaft as least the front end of which is fixed to the casing, a piston having a piston head in front thereof, which piston is slidably fitted over the outer periphery of the main shaft to reciprocate, and coaxially supporting an armature, a spring disposed between the piston and the casing for biasing the piston in one direction, an electromagnet fixed to the casing so as to attract the armature in the opposite direction against the biasing force of the spring, suction ports and suction valves for sucking a fluid into a pressure chamber defined by the cylinder and the piston head, and a discharge port and a discharge valve for discharging the pressurized fluid from the pressure chamber.

Abstract: An electrically driven diaphragm suction or pressure pump includes an oscillating anchor magnet that serves as the driving motor. The oscillating anchor magnet has a magnet coil (16), which is concentrically enclosed by a ferromagnetic closing cage (19) which is discontinuous in a circumferential direction. In the interior space of the magnet coil (16), the closing cage forms two pole rings (25,26), separated from one another in the axial direction by a circular slot (27). The closing cage is tightly arranged in a case (28,29). To obtain a high efficiency and high pump capacities, the central anchor shank (39), which is connected to the pump diaphragm, of the oscillating anchor (8), which is provided with a ferromagnetic solenoid plunger (38), is attached to two leaf-type vibratory springs (42, 43), each of which carries and centers on one side an end section projecting out of the closing cage (19) of the magnet coil (16).

Abstract: A new and improved control system for monitoring and controlling the operation of a downhole linear d.c. motor-pump assembly and a method of using it for producing a sufficient reciprocating pumping action to lift well fluid through the producing tubing of a well to the ground surface. The system includes a surface monitoring station that is in radio communication with a plurality of remote downhole motor-pump assemblies. Each motor-pump assembly has a surface motor controller, a downhole motor-pump cartiridge unit that is adapted to be received in a downhole cartridge sleeve assembly that maintains the cartridge unit in a stationary position for pumping purposes. The motor-pump cartridge unit may be raised or lowered by a control cable within the production tubing for helping to facilitate the repair or replacement of the motor-pump cartridge unit.

Abstract: An electromagnetic pump includes a sleeve member, a resin coil bobbin, a ring-like printed circuit board, a ring-like holder, a plurality of studs, a pump housing, and a projecting portion. The sleeve member houses a plunger for controlling an operation of a control valve. The coil bobbin is arranged around the sleeve member, has a pair of flanges, and winds an excitation coil. The printed circuit board is stacked on the outer surface side of one flange of the coil bobbin with a predetermined interval therebetween and has a surface which faces the coil bobbin and on which various types of electronic parts are mounted. The holder is stacked on the side of the printed circuit board opposite to the coil bobbin with a predetermined interval therebetween. The studs project from the outer surface of the one flange of the coil bobbin and an inner surface of the holder and integrally form a stacked body.

Abstract: A magnetically actuated linear displacement compressor for use in an oxygen concentrator is provided, including a cylinder and a diaphragm mounted for reciprocating movement in the cylinder. The diaphragm divides the cylinder into two longitudinal portions and includes a permanent magnet and a peripheral edge that sealably engages the inside surface of the cylinder. Gas is introduced into and discharged from each of the cylinder portions. There is a linear actuator that includes a series of windings arranged along the cylinder. Successive groups of at least one of the windings are selectively energized and de-energized in a reciprocating pattern to generate a reciprocating magnetic field which drives the diaphragm reciprocally through the cylinder such that gas is alternately drawn into and discharged from one cylinder portion while the reverse sequence occurs in the other cylinder portion.

Abstract: A cable length adjustment device comprising an elongated member, a locking member formed to prevent translatory movement of the elongated member when in a first locked position, and allow for translatory movement of the elongated member in a second unlocked position, and a housing substantially encasing the locking member.

Abstract: A displacement or power mechanical oscillator comprises an oscillation space constituted by a sector of an annular cavity, having a rectangular cross-section in a plane through the axis of the cavity and vertically oriented plane of symmetry. The cavity contains a sealing liquid and a vane in closed matching relationship with the inner walls of the cavity. The vane is symmetrically oscillatable with the liquid in the narrow gaps between vane and cavity walls providing a liquid dynamic seal.

Abstract: An electromagnetic reciprocating pump comprises a pressure sensor for detecting the actual outlet pressure of the electromagnetic reciprocating pump, and the strokes of the electromagnetic drive means and the compressor piston connected to the electromagnetic drive means varies are feedback controlled by the deviation from the present outlet pressure of the actual outlet pressure detected by the pressure sensor. The stroke of the electromagnetic drive means is controlled by adjusting the average magnitude of the half-wave AC current supplied to the electromagnetic drive means.

Abstract: An electromagnetic reciprocating pump having a piston electromagnetically moved at least in one direction is comprised of a frame having attached thereto an electromagnet which operates the piston, an inner cylinder whose one end side in the axial direction is secured to the frame and the other side thereof is closed and having the piston accommodated therein such that the piston can be reciprocated therein, an outer cylinder whose one end in the axial direction being secured to the frame and coaxially encircling the inner cylinder so as to form a working chamber between it and the inner cylinder, an outer piston accommodated within the working chamber so as to freely reciprocate and varying a capacity of working chamber, spring means being contracted and expanded in accordance with the movement of the outer piston, and magnetic coupling means for magnetically coupling the inner piston and the outer piston.

Abstract: A solenoid-operated reciprocating pump includes a casing having a cylinder with a central axis. A main shaft is disposed in and secured at one end to the casing in alignment with the central axis of the cylinder. A piston having a piston head is slidably fitted over the main shaft such that the piston head is disposed within the cylinder for axial motion. A coil spring extends between the piston and casing to bias the piston in a first axial direction and an armature radially extends from the outer periphery of the piston for interaction with an electromagnet disposed around the longitudinal periphery of the piston. The electromagnet attracts the armature and hence the piston in a second axial direction opposite from the first direction.

Abstract: A linear motion reciprocating pump having a cylindrical housing, a magnetically permeable plunger mounted for reciprocal motion in said housing, the plunger including an opening to permit the passage of fluid from one end of the housing through the plunger to the other end of the housing, a power coil mounted on one end of the housing for attracting the plunger toward the one end, a reset coil mounted on the other end of the housing for attracting the plunger toward the other end of the housing, an electrical circuit operatively connected to energize the coils, the circuit including means for alternately controlling the enerization of the coils in phase to reciprocate said plunger in the housing whereby the voltage across the energized coil crosses through zero causing the plunger to be expelled from the energized coil just prior to energization of the other coil.

Abstract: An electromagnetic reciprocating piston fluid pump having a housing defining a piston guide, an inlet port, and an outlet port, and a piston disposed in the piston guide. A blocking oscillator periodically energizes a solenoid coil to reciprocate the piston in the piston guide and valves provide for unidirectional fluid flow through the pump. A soft rubber bumper and a semi-rigid plastic washer are disposed at the output end of the piston guide to noiselessly terminate the displacement of the piston at the end of its pumping stroke.

Abstract: Pumping apparatus which compresses or decompresses an actuating fluid alternately, which is in turn used to pump an artificial heart. To reduce the size of the apparatus, a diaphragm which contains a non-compressible actuating liquid is driven reciprocatingly by an electric linear motor. To prevent the occurrence of an excessive suction pressure which may be caused by the non-compressibility of the actuating fluid, at the commencement of the suction interval, the current to energize the linear motor is increased gradually and the pressure of the actuating liquid is detected. When the liquid pressure goes out of a selected safety range, the gradual increase ceases. A discharge stroke is detected from an integrated value of the motor current during the discharge interval, and when it reaches a given value, a reversal of the direction of energization of the motor is initiated.

Abstract: An electromagnetic type reciprocating pump comprises an electromagnet whose magnetization and demagnetization are repeated by a half wave-rectified version of alternating current or direct current in the form of pulses, a piston having a magnetic member which is attracted by the magnetization of the electromagnet, a cylinder in which the piston is inserted and guided, a first urging member for imparting a reaction force in a backward direction to the piston which is moved in a forward direction and a second urging member for imparting a reaction force, which is weaker than that of the first urging member, to the piston in the forward direction.

Abstract: A new and improved control system for monitoring and controlling the operation of a downhole linear d.c. motor-pump assembly and a method of using it for producing a sufficient reciprocating pumping action to lift well fluid through the producing tubing of a well to the ground surface. The system includes a surface monitoring station that is in radio communication with a plurality of remote downhole motor-pump assemblies. Each motor-pump assembly has a surface motor controller, a downhole motor-pump cartridge unit that is adapted to be received in a downhole cartridge sleeve assembly that maintains the cartridge unit in a stationary position for pumping purposes. The motor-pump cartridge unit may be raised or lowered by a control cable within the production tubing for helping to facilitate the repair or replacement of the motor-pump cartridge unit.

Abstract: A positive displacement pump is provided which is especially suited to be used as a left ventricle assist device (LVAD). The pump is electromagnetically actuated. An electromagnet produces a pulse which repels a magnet mounted in a diaphragm which forms one wall of a pumping chamber. The pumping chamber thereby constricts and fluid is expelled. The electromagnet has a reverse taper core and core cup magnet which produce a bipolar field effect upon a diaphragm magnet to cause the return of the diaphragm to its starting position, without the application of external power.

Abstract: A long life, very low friction pump for use in a heat pipe pump or the like is disclosed. A first pump uses magnetically confined ferrofluid rings as both sealer and lubricant for a sliding pump piston in a two sided piston pump that minimizes the seal pressures on both sides of the ferrofluid seals. A second pump uses a magnetically confined ferrofluid slug as a self-sealing and self-repairing pump piston.

Abstract: This invention relates to an auxiliary heating system for vehicles which is intended for effective heating of vehicles by installing it together with a pre-existing vehicle heating system. This invention utilizes a modified boiler with an improved burner as a heat source instead of engine waste heat. In addition, the invention features various kinds of safety devices. The invention provides for increased efficiency in the heating of a vehicle and yet represents an inexpensive heating system. The invention also expands the scope of vehicles in which the above heating system can be installed by decreasing the weight and lessening the size of the boiler.

Abstract: A toroidal circumferentially wound superconducting coil is provided for generating a constant magnetic field with a significant radial field component. A room-temperature resistive coil wound circumferentially and connected to launch activating means is coaxial with the superconductive coil. Interaction of the current in the resistive coil with the radial field component of the superconductive coil produces an axial force on the resistive coil and in turn on the launch activating means. The axial force is controllable in magnitude and direction by controlling the magnitude and direction of the current supplied to the resistive coil.

Abstract: A gas compressor for use in a gas refrigerator includes a compression space having a volume varied with a positional shift of a piston when the latter reciprocates in a cylinder, a first buffer space communicating with the compression space in one direction with respect to the compression space and a second buffer space communicating with the compression space in the opposite direction. Forces acting on working surfaces of the piston are set in such a way that, when a reciprocation stroke of the piston is to be lengthened, a shift of a neutral position of the piston reciprocation toward the compression space is prevented and, when the reciprocation stroke is to be shortened, a shift of the neutral position away from the compression space is prevented, so that the dead space in the compression space is minimized and a highly efficient operation can be realized in a wide output control range.

Abstract: A vacuum pump provided with a restoration coil spring 18 having a reduced size and reduced biasing force to render an overall size of the pump compact includes a casing which defines therein a pumping chamber 6 and an operational chamber 3; a piston 7 reciprocally disposed in the pumping chamber, the piston dividing the pumping chamber into front and rear compartments R1, R2; an operational mechanism disposed in the operational chamber for moving the piston; and, a piston rod 4 having one end connected to the piston, the piston rod extending through the rear compartment and the operational chamber. The operational mechanism includes a solenoid armature 13 on the piston rod, and an electromagnet 14, 15 in the operational chamber.

Abstract: An electromechanical linear motor incorporating a number of electrically conductive drive coils arranged axially and embedded in a composite matrix so as to form a hollow cylinder within which a piston or pistons are placed. Permanent magnets or conductive coils arranged around the circumference of the pistons interact through magnetic coupling with the drive coils so as to cause the piston to move in accordance with the currents applied to the drive coils. These currents are supplied through logic control circuitry which receives inputs from a number of sensors including piston position sensors, thermostats, pressure transducers and timers. Based on the information received from these sensors, a microprocessor controlled power circuit provides electrical pulses of a frequency, amplitude and duration designed to produce piston motion appropriate to the specific application.

Abstract: An electromagnetically-actuated fuel piston pump is constructed so as to eliminate the distracting pumping noises occurring during the functioning by using a dampening elastic element arranged at a site protected against contact with the delivered fuel by seals. The seals accomplish a bearing of the cylinder, which simplifies the fabrication.

Abstract: An electrically operable liquid soap dispenser responsive to the presence of a user dispenses a measured amount of soap on demand. It has a spout with a fluid conduit therein connecting a soap reservoir and a nozzle. A pump draws soap from the reservoir during a stroke of its plunger and depending on the embodiment, ejects a measured amount of soap during a subsequent plunger downstroke or upstroke. At least one check valve regulates the flow of soap from the reservoir to an orifice at the nozzle. The soap path from the reservoir to the nozzle is kept full of soap so that a single cycle of the pump is sufficient to eject the desired amount of soap. The orifice is sized and shaped so as to prevent dripping while maintaining soap at the nozzle ready to be ejected. A light beam emitter and detector control operation of the pump.

Abstract: A device for transporting and preheating fuel which is susceptible to cold temperatures comprises a pump which has an electromagnetic coil which is supplied with current to move a plunger for pumping the fuel so as to transport it. The plunger is returned for example, by a return spring and the electromagnetic coil is set out so that a maximum portion of the coil heats a fuel as it is passed through a pumping space. In accordance with the method of the invention, the coil has its own current supply control which advantageously may be set to supply a heating current which is in excess of that required for moving the plunger. A return spring set for returning the plunger may also be made stronger than necessary to effect return and the timing of the operation of the coil for moving the plunger may be set to be longer than necessary in order to keep the coil at a higher operating temperature and thus transform more heat to the fuel.

Abstract: A linear motor compressor within a cryogenic refrigerator wherein the compressor space, within which a gaseous fluid is alternately compressed and expanded, is formed by a stationary piston and a reciprocating armature that is concentric about the piston. The armature is supported along a clearance seal the stationary piston. An axial bore along the stationary piston conveys gaseous fluid from the compression space to a displacer within the cold finger of the cryogenic refrigerator. An isolator for reducing transimission into and out of the compressor comprising a dynamic absorber and flat springs mounted with a damping material between the compressor and a mounting frame. A sensor for detecting the position of the armature utilizes a target magnet whose magnetic flux lines are decoupled from the flux lines generated about the coil.

Abstract: A water-tight structure for a multicore cable includes a sealed vessel in which electrical components are arranged, and a grommet having an insertion hole disposed at a multicore cable lead portion of the sealed vessel. The multicore cable is held in the insertion hole of the grommet and has a solder-dipped portion in the grommet which has been bent, a portion of the solder-dipped portion being covered with a metal sleeve.

Abstract: An electromagnetic fluid pump having a generally cylindrical housing divided into an inlet chamber, an outlet chamber and an intermediate chamber by a pole member and a separator plate. The pole member is sealingly attached to the wall of the housing and divides the inlet chamber from the intermediate chamber. A first O ring provides a gas tight seal between the pole member and a piston guide which provides a fluid passageway between the inlet chamber and the outlet chamber. The separator plate is sealingly attached to the end of the piston guide adjacent to the outlet chamber and separates the outlet chamber from the intermediate chamber. A second O ring provides a gas tight seal between the internal wall of the housing and a rim portion of the separator plate. An electrical connector having a connector pin provides electrical power to an electronic circuit periodically energizing a solenoid coil to reciprocate a piston disposed in the piston guide.

Abstract: An electromagnetic pump includes a cylindrical member, a resin coil bobbin, a printed circuit board, a holder, and pump housing. Engaging projections are formed on a peripheral portion of a surface of the coil bobbin, which opposes the lid, and the electromagnetic pump components are held in the pump housing while they are biased in the axial direction of the cylindrical member by utilizing the engaging projections.

Abstract: An electrical device which includes axially aligned solenoids and a plunger with two cores, each of which is located at least partially in a respective one of the solenoids. A controller, operated by synchronism with the plunger, is used to energize the solenoids alternately so that the plunger is reciprocated relatively to the solenoids by the action of the resulting magnetic field on the cores. The device may be combined with a pump, particularly a piston pump, to provide a compact, efficient pumping unit which may be submersible.

Abstract: A reciprocating pump suitable for use in an implantable medication dosage device has a piston movable in a chamber connected to a medication reservoir, the chamber having an output closable by a check valve. The check valve includes a movable element which is acted upon by a biasing system to urge the moveable element in a direction to close the check valve. The moveable element has a sealing surface against which an end face of the piston presses with tight adjacency as the piston moves to an extreme position during its output stroke.

Abstract: An electromagnetically reciprocating apparatus includes a piston assembly which is driven by an electromagnet repeating magnetization and demagnetization and a compression coil spring so as to reciprocate a front and rear pistons of the assembly in a front and rear cylinders. An air hole is formed in the rear cylinder to communicate a sealed inner space partitioned in the cylinder by the rear piston with an atmosphere. A valve is mounted on the air hole to adjust a resonance frequency of the vibration system of the apparatus.

Abstract: A biasing force adjusting apparatus is used for an electromagnetically driven reciprocating pump in which the piston is reciprocated to achieve pumping by a magnetic force cyclically generated from an electromagnet and a biasing force of a compression coil spring. The apparatus includes a pressing mechanism having a piston-cylinder unit to which a compressor is connected. The unit is detachably connected to a spring support to press the support at a predetermined pressure, and then a fixing screw is tightened to fix the support on a housing of the pump.

Abstract: A low pressure metering pump having a hollow piston reciprocated in a cylindrical guide by a solenoid coil. A pair of check valves provide for unidirectional fluid flow through the cylindrical guide in response to the reciprocation of the piston. A seal attached to the piston prohibits a fluid backflow between the external surface of the piston and the internal surface of the cylindrical guide. A bumper seal at the output end of the piston prevents fluid flow through the cylindrical guide when the solenoid coil is de-energized. A control circuit periodically energizes the solenoid coil at a frequency determined by a variable resistance responsive to predetermined operational parameters. In a preferred embodiment, the metering pump is a fuel control element for a heater and the variable resistance is a thermistor or similar type of temperature sensitive resistance, which controls the rate at which fuel is delivered to the heater.

Abstract: A check valve having a dual valve seat, a valve member, a retainer, and a valve spring. The dual valve seat has a cylindrical body having an axial bore therethrough. A conical valve seat is provided at one end of the axial bore and a flat valve seat is provided at the other end of the axial bore. A recess is provided in the face of the cylindrical body at the end having the conical valve seat to form a first retainer seat and an annular recess is provided about the flat valve seat to form a second retainer seat by inverting the valve seat, the check valve may accept either a stem valve member having a conical sealing surface or a flat valve member having a flat sealing surface. The embodiment of this check valve in an electromagnetic fluid pump permits it to have different operating characteristics depending on which valve member is used.

Abstract: A valve assembly (16) for an oscillating pump (10) of the type having a reciprocating armature (12) which carries an impeller (13) includes a rigid valve seat (17) carried by and movable with the impeller (13). The assembly (16) also includes an elastomeric valve (18) which is carried by the valve seat (17) within the impeller (13) and which divides the pump chamber therein into an inlet side (14) and outlet side (15). Reciprocation of the armature (12) first causes the valve (18) to engage the valve seat (17) to discharge fluid from the outlet side (15) of the pump chamber and then causes the valve (18) to disengage the valve seat (17) to permit fluid to pass from the inlet side (14) to the outlet side (15) of the pump chamber.

Abstract: A reciprocating electric motor for wells includes a stator comprising a stack of coil groups surmounted by an annular power pack, the whole being mounted on a non-ferromagnetic tube and potted and slipped into a tubular ferromagnetic housing, the coils being helically wound strips of conductive material with their outer ends folded down to extend paraxially and their inner ends folded radially thereacross and then down paraxially to provide connections between like coils in each group forming a plurality of sets for simultaneous energization, and an armature extending through the stator coils and annular power pack for reciprocation therewithin, the armature including alternating ferromagnetic and non-ferromagnetic sections.

Abstract: A reciprocating pump having a fluid assembly having a fluid wing at its input side encompassing an admission line and an admission chamber. A moveable valve part of, for example, a magnetizable material is arranged in the admission chamber. A component part, for example a permanent magnet, which attracts the valve part against a valve seal is situated outside of the fluid wing. The valve part and the component part together form a magnetic spring system. An advantage of this arrangement is an extremely small dead spacing inside the fluid wing. Resulting therefrom is that gas bubbles can also be conveyed with great reliability. Also harmful interaction between the conveyed medication and the component part such as, for example, corrosion of the component part or conversions of the medication influenced by the component part, cannot occur.

Abstract: A magnetostrictive hydraulic injector pump having a cylinder closed at one end with an elongated piston arranged within the cylinder from the other end. The piston is constructed of a magnetostrictive material which increases in length in the presence of a magnetic field of appropriate intensity. It is wound along its length with a coil of wire capable of producing an electro-magnetic field. The piston includes an intake passage communicating with a fluid supply. The piston is fastened at the open end of the cylinder to define a cylinder cavity between the cylinder closed end and the piston. An injector passage including a valve, communicates with this cavity to the exterior. The volume of this cavity is reduced when the piston expands under the influence of the magnetic field created by the coil to produce a pressure on any fluid contained within said cavity to force it out the injector passage.

Abstract: An electromagnetic linear motor having a variable length stroke and providing a substantially large force in both its power stroke and return stroke includes concentric inner and outer magnetic circuits arranged coaxially for movement relative to one another in a rectilinear path with reciprocating motion in response to the interaction of magnetic fields produced by the inner and outer magnetic circuits, respectively. The length of the stroke and the rate of reciprocation are directly proportional to the magnitude of the voltage used to excite primary and secondary coils which generate the respective magnetic fields and the rate at which the polarity of the voltage applied to the secondary coil is changed between negative and positive polarities.

Abstract: A free-piston reciprocating compressor includes a reciprocating piston disposed within a cylinder such that one end of the piston-cylinder provides for a compression space and the other end of the piston-cylinder provides for a balancing space. The piston is coupled to and reciprocatingly driven by the armature of a linear electrodynamic motor, which armature reciprocates on guide means. The compressor also includes porting means operative to establish a stabilizing gradient sufficient to keep the piston operating at a related fixed mid-stroke position. The motor armature is also coupled to a centering-resonance spring.

Abstract: An electromagnetic fluid pump having a magnet attached to a reciprocating piston and a hall effect switch detecting the magnetic field generated by the moving magnet. In a first position of the magnet, the magnetic field through the hall effect switch is in a first direction causing the hall effect switch to generate a signal having a first polarity. In a second position of the magnet the magnetic field through the hall effect switch is reversed, reversing the polarity of the signal generated by the hall effect switch. An electronic switch circuit responsive to the signal generated by the hall effect having the first polarity to energize the solenoid coil to retract the piston from the first position to the second position against the force of a spring and further responsive to the signal having a reversed polarity to deenergize the solenoid coil when the piston is in the second position.

Abstract: In an electromagnetic pump, the inner end of an outlet pipe fixed in a pump housing extends for a predetermined length inside a sleeve housing a plunger to form a pump delivery pulsation absorption chamber around the outlet pipe. The inner end opening of this pipe is selectively closed by a control valve serving as a guide member for slidably guiding a valve body of a delivery valve along the axial direction. The fuel leakage prevention control valve and the pulsation absorption chamber are simply and optimally formed with a single construction.

Abstract: An oscillatory pump includes a cylinder (9) having normally-closed valves (10,13) of flexible material fixedly located at the inlet (A.sub.c) and outlet (B.sub.c) ends of the cylinder (9), and a piston (1) having an inlet (A.sub.p) and an outlet (B.sub.p). The piston (1) is reciprocatable within the cylinder (9) and is provided with a further valve (6) of flexible material movable with the piston (1) and located at the outlet end (B.sub.p) of the piston (1). The piston (1) is constructed to allow fluid to pass from an inlet chamber (C1) formed between the inlet valve (10) and the inlet end (A.sub.p) of the piston (1) to an outlet chamber (C2) formed between the further valve (6) and the outlet valve (13) in response of the piston (1) within the cylinder (9). The valve includes a valve seat having a generally conical first surface portion and a second surface portion located radially inwardly of the first surface portion and extending generally parallel to the axis of the first surface portion.

Abstract: An apparatus for recovering oil from a subterranean hydrocarbon-bearing formation wherein a subsurface pump in the wellbore is driven by an electromagnet submersed in the wellbore above the pump.