Abstract: A linear compressor comprises: a fixed member including a cylinder for providing a refrigerant compression space; a movable member, which includes a piston for compressing refrigerant inside the cylinder and a supporter composed of a center portion being aligned with a center of the piston and a support portion extended radially of the piston and which makes a linear reciprocating movement about the fixed member; a plurality of mainsprings supported on the support portion of the supporter, for elastically supporting the piston in an axial direction; and a mass member, which includes a center portion to couple with the center portion of the supporter and a plurality of ends extended from the center portion to maintain an air-gap towards the support portion of the supporter and towards the mainsprings.

Abstract: A stator for a linear compressor comprises a coil winding, in which a coil winds in a circumference direction and current flows; a bobbin set, which is wound with the coil winding and which insulates the coil winding; and a plurality of core blocks, which are arranged in a circumference direction of the bobbin set at predetermined intervals from an axial direction of the bobbin set, which is advantageously used for simplifying the manufacturing process, enhancing the clamping force, cutting an overall production cost, and reducing the size of a product incorporating the same.

Abstract: A compressor unit having a cylinder and a piston, wherein the cylinder and the piston delimit a compressor chamber. The compressor unit also includes a capsule that surrounds at least the cylinder and the piston and a linear drive to drive a relative movement of the cylinder, the piston and the capsule. The compressor chamber has an outlet opening that opens into an interior of the capsule.

Abstract: A driving controlling apparatus for a linear compressor, comprises: a storing unit for storing a reference phase difference to judge an overload state; and a controlling unit for judging an overload state based on a comparison result between the reference phase difference and a phase difference between a current and a stroke, and controlling a voltage or a current applied to a linear motor based on the judgement result.

Abstract: A refrigerant suction guide structure of a reciprocating compressor is provided. The refrigerant suction guide structure includes a cylinder having an accommodating space inside, a piston having suction channels through which refrigerant is inhaled inside and inserted into the cylinder to be in a linear reciprocating motion, a suction valve included in the end of the piston to open and close the suction channels, and a valve fixing member for combining the suction valve with the piston. The suction channels of the piston include inclined surfaces for guiding refrigerant to the outside in which the suction valve is first opened. The suction channels are formed so as to be inclined to reduce flow resistance of inhaled refrigerant such that the amount of the inhaled refrigerant is increased. Therefore, it is possible to improve the efficiency of a compressor.

Abstract: A linear featuring an improved oil feed performance compressor comprises a cylinder having a refrigerant compression space inside; a piston, linearly reciprocating inside the cylinder to compress refrigerant; a frame, to which one end of the cylinder is affixed and which has a mounting groove at a lower portion; an oil feed assembly settled in the mounting groove of the frame, for pumping/supplying oil; an oil supply path in a linear shape, which is positioned at a lower portion inside the frame to communicate with the mounting groove of the frame and with the bottom of the cylinder and which supplies oil between the cylinder and the piston; and an oil recovery path in a linear shape, which is at an upper portion inside the frame asymmetrically to the oil supply path to communicate with an upper side of the frame and with the top of the cylinder and which recovers oil between the cylinder and the piston.

Abstract: A linear compressor (100) comprises: a stationary member including a cylinder (200) for providing a space for compressing a refrigerant; a movable member linearly reciprocating with respect to the stationary member, and including a piston (300) for compressing the refrigerant inside the cylinder (200) and a supporter piston (320) having a support portion extended in a radial direction of the piston (300); a plurality of front main springs (820) positioned so as to be symmetrical with the center of the piston (300) and the supporter piston (320), one ends of which being supported by the front surface of the support portion of the supporter piston (320) and the other ends of which being supported by the stationary member; one rear main spring (840), one end of which being supported by the back surface of the supporter piston (320); a suction muffler (700) providing a passage for introducing a refrigerant while reciprocating with the movable member, reducing noise, and including an extended part extended toward

Abstract: Fluid transfer devices for use in, for example, ambulatory infusion devices and infusions devices including fluid transfer devices.

Abstract: The present invention relates to a linear compressor (100); and more particularly, to a linear compressor (100) provided with three mainsprings (820,840) having a resonance frequency synchronized with an operating frequency, where the resonance frequency can be adjusted without varying initial positions of mainsprings (820,840) although an additional mass member (1000) may be added.

Abstract: A linear compressor comprises: a stationary member including a cylinder (200) for providing a space for compressing a refrigerant; a movable member linearly reciprocating with respect to the stationary member, and including a piston (300) for compressing the refrigerant inside the cylinder (200) and a supporter piston (320) connected to the piston (300) and having a support portion extended in a radial direction of the piston (300); a plurality of front main springs (320) positioned so as to be symmetrical with the center of the piston (300) and the supporter piston (320), one ends of which being supported by the front surface of the support portion of the supporter piston and the other ends of which being supported by the stationary member; one rear main spring (840) positioned at the opposite side of the piston (300), one end of which being supported by the supporter piston (320); and a back cover (560) having a support portion for constraining the other end of the rear main spring (840) from moving in a tr

Abstract: The present invention provides a linear compressor, including: a cylinder having a compression space of refrigerant therein; a piston linearly reciprocated inside the cylinder in an axis direction to compress the refrigerant; and a frame having a mounting hole so that one end of the cylinder can be mounted thereon, and also having a deformation prevention portion in some section around the mounting hole brought into contact with the one end of the cylinder. Even though the size of the cylinder is increased and the size of the frame is limited, the frame is provided with enough strength to support the cylinder, thereby reducing fastening deformations and improving operation reliability.

Abstract: The present invention provides a linear compressor including: a shell (110); a fixed member installed inside the shell (110), and including a cylinder (200) for providing a compression space of refrigerant introduced into the shell (110); a moving member including a piston (300) for compressing the refrigerant sucked into the compression space inside the cylinder (200), and being linearly reciprocated with respect to the fixed member; and a suction muffler (700) positioned on a suction passage of the refrigerant inside the shell (110), a suction volume with a larger sectional area in a central portion than in both ends being defined in the suction muffler (700).

Abstract: The present invention relates to a method and related apparatus for rotating a piston of a drug pump during the pumping stroke to reduce drug pump wear. The actuator may move a piston that pumps fluid through a pumping channel. In the present invention, the armature includes one or more openings or shapes that cause the actuator, including the armature and the piston, to rotate about a longitudinal axis of the piston during the pumping stroke. Rotation of the actuator member may help to reduce wear to the actuator member and the pump itself caused by repetitive pumping motions.

Abstract: An apparatus and method for controlling an operation of a reciprocating compressor are disclosed. The apparatus for controlling an operation of a reciprocating compressor includes: a TDC/BDC detecting unit for detecting a TDC and a BDC of the reciprocating compressor; and a controller for independently controlling the TDC and the BDC so as to fit each reference position based on the detected TDC and BDC. Efficiency of the reciprocating compressor can be enhanced by independently controlling a top dead center and a bottom dead center.

Abstract: An apparatus for delivering a fluid includes a housing, an inlet in the housing for receiving the fluid, and an outlet in the housing for discharging the fluid. A piston channel is provided within the housing through which the fluid flows from the inlet to the outlet. An actuator is positioned within the housing and is moveable between a retracted position and a forward position, the actuator defining a piston chamber for storing fluid received through the inlet when the actuator is in the retracted position and for driving the fluid stored in the piston chamber toward the outlet when the actuator transitions from the retracted position to the forward position. The actuator includes an armature and a piston coupled to the armature and moveable within the piston channel. The piston is provided with a groove in an outer surface for conducting fluid from the inlet to the outlet.

Abstract: A deep well pump, especially a numerically controlled reciprocating submersible pump with freely adjustable parameters, includes a balancing sieve tube, a drive and a pump. The drive includes a stator with airtight cavity and reciprocating head with iron cores inside the stator. The stator and the reciprocating head form a friction couple via supporting guides and the reciprocating head iron cores. The stator's upper end is connected to the pump's lower end through the sieve tube. An oil tube is connected to the pump. The stator's lower end is connected to the balancing sieve tube, end plug and end coupler serially.

Abstract: A drive mechanism for delivery of infusion medium has a coil and an armature moveable toward a forward position, in response to the electromagnetic field produced by activation of the coil. A piston is moveable axially within a piston channel to a forward position, in response to movement of the armature to its forward position. The armature and piston are moved toward a retracted position, when the coil is not energized. In the retracted position of the piston, a piston chamber is formed between the piston and a valve member and is filled with infusion medium. As the piston is moved to its forward position, the piston chamber volume is reduced and pressure within the piston chamber increases to a point where the pressure moves the valve member into an open position through an outlet.

Abstract: A fluid-guiding and electric conducting system for a suspended electric submersible PCP comprises a fluid-guiding system and an electric conducting system. The fluid-guiding system comprises an upper connector, a protector, a fluid-guiding sleeve, a driving mechanism, a shaft coupling, a first annular cavity, a second annular cavity, a third annular cavity, a fourth annular cavity, and a fluid outlet. The first annular cavity, the second annular cavity, the third annular cavity, the fourth annular cavity, and the fluid outlet are connected orderly to the well fluid pipe. The electric conducting system comprises a motor lead wire, a center hole of the protector, a fifth annular cavity, and a wire outlet. The fluid-guiding and electric conducting system has the advantages of simple structure, low manufacturing cost, easy assembly and inexpensive maintenance.

Abstract: A two stage reciprocating compressor includes a casing. A first compressing unit is disposed in the casing and includes a first piston and a first cylinder, the first compressing unit being driven by a reciprocating motor to linearly reciprocate the first piston in the first cylinder to suck in and compress gas. A second compressing unit is disposed in the casing and includes a second piston and a second cylinder, the second compressing unit being driven by vibration of the first compressing unit to linearly reciprocate the second piston in the second cylinder to suck in and compress gas. A vibration transfer member transfers the vibration from the first compressing unit to the second compressing unit. The first and second compressing units extend in parallel and face in the same direction, the second compressing unit being located adjacent to a suction passage of the first compressing unit.

Abstract: A drive mechanism for delivery of infusion medium a coil capable of being electrically activated to provide an electromagnetic field. The coil surrounds a piston channel extending in an axial direction. An armature is located adjacent the coil, on one side of the axial channel. The armature is moveable toward a forward position, in response to the electromagnetic field produced by activation of the coil. A piston is located within the piston channel and is moveable axially within the channel to a forward position, in response to movement of the armature to its forward position. The armature and piston are moved toward a retracted position, when the coil is not energized. The armature may be configured with a reduced diameter by including a coil cup for supporting the coil including a shelf portion defining at least a portion of a pole surface of the coil cup.

Abstract: A linear compressor having an electromagnet; an oscillating body movably guided in an oscillating fashion in the alternating field of the electromagnet; a cylinder; a piston connected to the oscillating body and movable back and forth inside the cylinder; a power supply circuit to supply the electromagnet with an alternating current; a proximity sensor to detect whether a distance between the piston and the end face of the cylinder falls below a predetermined threshold value; and a control circuit to detect a time period in which the distance between the piston and the end face of the cylinder falls below the threshold value and to regulate an amplitude and/or a phase of the alternating current if the time period deviates from a positive setpoint value.

Abstract: An apparatus for delivering a fluid includes a housing, an inlet in the housing for receiving the fluid, and an outlet in the housing for discharging the fluid. A piston channel is provided within the housing through which the fluid flows from the inlet to the outlet. An actuator is positioned within the housing and is moveable between a retracted position and a forward position, the actuator defining a piston chamber for storing fluid received through the inlet when the actuator is in the retracted position and for driving the fluid stored in the piston chamber toward the outlet when the actuator transitions from the retracted position to the forward position. The actuator includes an armature and a piston coupled to the armature and moveable within the piston channel. The piston is provided with a groove in an outer surface for conducting fluid from the inlet to the outlet.

Abstract: A method of displacing a pumping assembly. In a first step, a first current is applied in a first direction through a coil assembly to displace a drive assembly from an initial position to cause a first pumping motion. Then, the drive assembly is returned to the initial position to cause a second pumping motion. At some point nearing the end of the second pumping motion, a second current is applied in the first direction through the coil assembly to decelerate the drive assembly before it reaches the initial position. A third current may be applied in a second direction through the coil assembly to cause or assist a return of the drive assembly to the initial position. An apparatus capable of carrying out the method is also disclosed.

Abstract: Disclosed herein is a linear compressor, which is designed in such a fashion that oil is suctioned into a space between a cylinder and a piston by a low pressure produced between the cylinder and the piston when the piston moves backward, and then is discharged to the outside by a high pressure produced between the cylinder and the piston when the piston moves forward, resulting in a simplified oil pumping structure and low cost.

Abstract: Disclosed herein is a linear compressor in which a piston reciprocally moves in a cylinder upon receiving a reciprocating drive force of a linear motor to compress working-fluid, for example, refrigerant, received in the cylinder. The linear compressor comprises the piston adapted to reciprocally move in the cylinder, the piston being internally formed with a suction path, a suction valve to open or close the suction path of the piston to selectively connect the suction path of the piston to the interior of the cylinder, and a suction valve stopper to limit the degree of opening of the suction valve, whereby no excessive stress is applied to the suction valve. This has the effect of eliminating damage and deformation of the suction valve, minimizing vibration and noise due to the opening/closing operations of the suction valve, and maintaining the compression efficiency of the compressor at a constant value.

Abstract: A mover stabilizing and stator cooling arrangement includes an upper sleeve surrounding the mover of the linear motor, a lower sleeve, a thermoconducting sleeve surrounding the stator and axially connected between the upper sleeve and the lower sleeve. The arrangement further includes a thermal grease filled in the space defined between the upper sleeve and the mover, the space defined between the thermoconducting sleeve and the stator, and the space defined between the lower sleeve and the outer tube for quick dissipation of waste heat. A stabilizer ring is set between the upper sleeve and the mover to stabilize axial movement of the mover. A piston and multiple one-way valve sets are mounted in the space between the lower sleeve and the outer tube for allowing adjustment of the volume in the thermoconducting sleeve responsive to expansion/contraction of the thermal grease due to temperature changes.

Abstract: A device for pumping and compressing fluids, particularly in micro-liter quantities. First and second polarized cylindrical magnets are mounted in a cylinder with an inlet and an outlet port. The first magnet is adapted to rotate on the axis of the cylinder and has a fixed longitudinal position on that axis. The second magnet is free to move longitudinally but kept from any rotational movement, as a piston in the cylinder. The inlet port is open when the piston magnet is repelled by the rotor magnet's polarity and the outlet is open when the piston magnet is attracted by the rotor magnet's polarity as it rotates.

Abstract: To provide a less expensive and high-efficient free-piston Stirling cycle machine with an outer diameter of entire machine being relatively small. In a Stirling cycle cooler as a free-piston Stirling cycle machine including a cylinder 7, a piston 18 which is reciprocable inside said cylinder 7 and an electromagnetic driving mechanism 19 for reciprocating said piston 18, said electromagnetic driving mechanism 19 is comprised of a mover 20 and a stator 35, said piston 18 and said mover 20 formed by disposing a permanent magnets 24 outside an inner yoke 23 made of magnetic flux conducting material are disposed in an axial alignment, and said stator 35 and said cylinder 7 are disposed in an axial alignment.

Abstract: The fluid drive unit includes a cylinder communicating with both end portions of a meandering passage formed in the heat transport device. In the cylinder, the piston is slidably arranged being capable of sliding in the axial direction. Fluid is charged in the spaces, which are provided on both sides of the piston, connected to the meandering passage. The solenoid coil, which is provided in the periphery of the side of the cylinder, periodically inverts the magnetic poles and reciprocates the piston in the cylinder. To drive the piston smoothly and reduce the amount of eccentricity, a pair of sliding members are provided at the end portions of the piston. When the fluid in the passage is vibrated by the movement of the piston, the apparent heat conductivity of the heat transport device is enhanced, and heat is quickly diffused from the heating body to the radiating portion.

Abstract: An apparatus for controlling a compressor includes a stroke calculator for calculating a stroke estimate value of a compressor based on a value of a current applied to a motor of the compressor and a value of a voltage applied to the motor of the compressor; an operation frequency reference determining unit for integrating the stroke estimate value to output an integrated stroke value, detecting a mechanical resonance frequency of the compressor based on the integrated stroke estimate value and the current value, and determining the detected mechanical resonance frequency as an operation frequency reference value; and a controller for varying a current operation frequency of the compressor according to the determined operation frequency reference value.

Abstract: A linear compressor in which an inner core is integrally mounted with a magnet to linearly reciprocate simultaneously and is also mounted on a core frame that comes into close contact with an outer circumference of a cylinder. With this configuration, the core frame is able to stably support the weight of the inner core, resulting in improved rigidity and reliability of the compressor.

Abstract: A metering pump, especially for feeding fuel to a vehicle heater, comprising a delivery plunger (50), which can be moved to and fro for delivering liquid medium, a guide sleeve (42), which partially accommodates the delivery plunger (50) and guides same for the reciprocating movement, wherein the guide sleeve (42) with an inner surface (46) thereof defines a pump ejection chamber (48) and it defines with an outer surface (60) thereof a channel arrangement (74) leading to the pump ejection chamber (48), wherein the guide sleeve (42) is carried in a carrier element (24) and is in contact with the carrier element (24) by its outer surface (60) essentially over the entire circumference in a first length area (58) and is located with its outer surface at a spaced location from the carrier element (24) in a second length area (64), wherein the channel arrangement (74) is provided between the carrier element (24) and the guide sleeve (42) in its second length area (64), is characterized in that in its second length

Abstract: An apparatus that fixes a stator of a motor of a reciprocal compressor is provided. The apparatus includes a front frame, a cylinder inserted into and coupled to the front frame, an outer stator supported by and contacting the front frame, an inner stator formed in a cylindrical shape and inserted onto an outside circumferential surface of the cylinder with a predetermined interval from an inside diameter of the outer stator, a mover inserted between the outer stator and the inner stator and coupled to a piston inserted into the cylinder, and a stator fixing device incorporated with the front frame to pass through the cylinder or the inner stator in a longitudinal direction that supports and fixes both sides of the inner stator.

Abstract: A valve control system for a wellbore includes a fiber composite actuator functionally coupled to a valve operating member and means for controllably charging an interior of the actuator with fluid under pressure. A valve for a wellbore includes a valve stem and a valve seat associated with a valve body. The valve stem and valve seat are configured to enable fluid flow from an inlet port in the valve body to an outlet port in the valve body when the stem is moved from the seat. An axial contraction fiber composite actuator is functionally coupled to the valve stem. The valve includes means for controllably charging an interior of the actuator with fluid under pressure.

Abstract: A free-piston linear compressor (1) controlled to achieve high volumetric efficiency by a controller including an algorithm (116) for ramping up input power until piston-cylinder head collisions are detected using a detection algorithm (117/118) which then decrements power input whereupon input power is again ramped up by algorithm (116). Non-damaging low energy collisions are achieved by the controller including a perturbation algorithm (119) which perturbates the input power ramp with periodic transient pulses of power to ensure piston collisions are provoked during the transient power pulses.

Abstract: A linear motor of the present invention has: a stator having a stationary iron core and a magnet wire; a mover having a moving iron core and a magnet; and a plate-shaped elastic member for supporting the mover in a manner to rock in the rocking directions. This construction eliminates a sliding portion for supporting the mover so that it can reduce the loss, which might otherwise accompany the reciprocation of the mover. Moreover, a linear compressor using this linear motor is high in efficiency and reliability.

Abstract: Disclosed are a reciprocating compressor and a refrigerator having the same. The reciprocating compressor comprises a casing, one reciprocating motor mounted at a frame unit provided in the casing for generating a linear-reciprocation driving force, a first compression unit for compressing a refrigerant directly sucked without passing through the inside of the casing by receiving the driving force of the reciprocating motor, and a second compression unit for mixing a refrigerant introduced into the casing and a refrigerant discharged from the first compression unit and then compressing the mixed refrigerant once more by receiving the driving force of the reciprocating motor. Accordingly, a refrigerant is consecutively compressed two times, components are simplified, and the compressor is easily controlled. Also, the refrigerator having the reciprocating compressor decreases a load of the reciprocating compressor thereby to enhance the efficiency of the refrigerator.

Abstract: Air-demand-controlled compressor arrangement, particularly for commercial vehicles, includes a motor unit for generating a rotating movement which, by way of an interposed rotational-speed-transmitting transmission unit, drives a compressor unit for generating compressed air from ambient air. A control unit triggers the generating of compressed air in the case of a compressed-air demand. The transmission unit is constructed in the manner of a transmission whose rotational speed can be varied, and the control unit interacts with the transmission unit in order to adapt the rotational speed of the transmission unit corresponding to the compressed-air demand.

Abstract: A beverage dispensing apparatus is disclosed, comprising a solenoid pump coupled between a fluid inlet and a fluid outlet for pumping the fluid from said inlet to said outlet, said pump comprising a spring-loaded linear pumping member axially displaceable between a spring-loaded position and a spring-released end position and a controller for the solenoid pump, said controller being arranged to energize the pumping member into an intermediate position between the spring-released end position and the spring-loaded position. Consequently, the solenoid pump has improved noise characteristics and can be used to control the flow rate of the fluid whilst still being energized in substantially every cycle of an alternating current.

Abstract: Disclosed is a structure for fixing a motor stator of a reciprocating compressor, the reciprocating compressor comprising: a frame unit mounted in a casing and elastically supported; a reciprocating motor including an outer stator coupled to the frame unit, an inner stator inserted into the outer stator, and a mover inserted between the outer stator and the inner stator; and a compression unit for compressing a refrigerant by receiving a linear-reciprocation driving force of the reciprocating motor, wherein the inner stator and the frame unit contacting the inner stator are coupled to each other by welding. According to this, the structure is simplified and a fabrication cost is reduced by facilitating a fabrication.

Abstract: The present invention discloses a linear compressor in which a piston is driven by a linear motor and linearly reciprocated inside a cylinder to suck, compress and discharge refrigerants. Even though load is varied, the linear compressor performs the operation in a resonance state by estimating a natural frequency of the piston and synchronizing an operation frequency of the linear motor with the natural frequency of the piston, and efficiently handles the load by varying a compression capacity by changing a stroke of the piston.

Abstract: A disposable concentrate pump where the small pump body is part of a liquid collapsible bag reservoir, and the actuating solenoid is mounted in the dispenser. When a new bag is loaded, the attached pump body is inserted into a solenoid. When the bag is empty the in-bag part of the pump will be disposed of, along with the empty bag.

Abstract: A linear compressor for multi-compression includes a stationary cylinder, a moving piston, and a stationary piston. The stationary cylinder has a first compression chamber formed therein. The stationary cylinder is provided at one side thereof with an outlet part. The moving piston is movable forward and backward by a linear motor, that compresses a fluid in the first compression chamber. The moving piston has a second compression chamber formed and is provided, at the position where the second compression chamber communicates with the first compression chamber, with a first valve. The stationary piston is fixedly disposed in the compressor. The stationary piston is fitted in the moving piston so that the fluid in the second compression chamber is compressed as the moving piston is reciprocated.

Abstract: This invention provides a compressor with brushless single-phase linear motor, which includes a movable cylinder associated with a permanent magnet array, at least a stationary electromagnetic winding set and a pair of stationary pistons. A partition plate is disposed in the movable cylinder to form a first sub-cylinder and a second sub-cylinder. The front ends of the pair of the stationary pistons are respectively placed in either of two openings of the movable cylinder at its two ends. An alternate current applied to the stationary electromagnetic winding set to generate alternately attracting/repelling forces to the permanent magnet array. The movable cylinder is hence alternately pushed forward and backward. The volumes of the first and second sub-cylinders are changed to compress air in the first sub-cylinder or the second sub-cylinder.

Abstract: A reciprocating compressor includes: a cylinder installed inside a casing and having a space therein; a piston disposed inside the cylinder; an inner stator fixed at an outer circumference of the cylinder; a magnet fixed at an outer circumference of the inner stator; and an outer stator disposed to maintain a certain distance from an outer circumference of the magnet. Accordingly, the number of components is reduced thus to reduce a manufacturing cost, and performance can be also improved.

Abstract: A drive unit for a linear compressor having a frame and a body configured for reciprocating movement connected to the frame by at least one diaphragm spring and means for guiding the body to allow linear reciprocating movement with respect to the frame, the drive unit including a coil spring for action on the reciprocating body and the frame, the coil spring being configured for extension and compression in a direction of movement.

Abstract: A pump including a stator, a rotor comprising an axial extension slidably and rotatably mounted at least partially in a rotor chamber of the stator, and at least first and second valves between an inlet and the rotor chamber, respectively between the rotor chamber and an outlet, that open and close as, a function of at least the angular displacement of the rotor. The pump comprises interacting cam elements on the rotor and stator and biasing means acting on the rotor for applying a force on the rotor in the axial direction of the stator cam element.

Abstract: A magnetic coupling system may be used in a fluid displacement apparatus to magnetically couple a drive shaft to a piston. The magnetic coupling system may include first and second magnetic couplers at the ends of the drive shaft and piston, respectively. The first magnetic coupler and second magnetic coupler may be configured to exert an attractive force. A bearing between the magnetic couplers reduces friction and side loading.

Abstract: An apparatus for controlling an operation of a compressor includes: a back electromotive force calculator for calculating a back electromotive force of a compressor based on a value of a current applied to a motor of the compressor and a value of a voltage applied to the motor of the compressor; an operation frequency reference value determining unit for detecting a mechanical resonance frequency of the compressor based on the back electromotive force value and the current value and determining the detected mechanical resonance frequency as an operation frequency reference value; and a controller for varying an operation frequency of the compressor according to the determined operation frequency reference value.

Abstract: It is an object of the present invention, in an electromagnetic reciprocating fluid device in which a movable member is equipped with permanent magnets, to resist a torque rotating the movable member about an axis thereof in the reciprocating direction. The electromagnetic reciprocating fluid device has a pair of electromagnets 28, 28? facing each other, and permanent magnets 26, 26? disposed in a space between the opposed electromagnets and held by a movable member 27. When an alternating current is applied to coils 34 formed in the electromagnets, a magnetic force is generated between the electromagnets and the permanent magnets, whereby a driving force for reciprocation is applied to the movable member. One end of the movable member is connected to a piston 18 of a first piston-cylinder assembly 12, while the other end is connected to a piston 18? of a second piston-cylinder assembly 12?.