Abstract: A molded liner member for a fluid pump is disclosed. The liner member includes a generally annular ring, having an inner surface, an outer surface which is substantially concentric with the inner surface, and first and second end surfaces. The annular ring is molded from fiber reinforced polymer, and a majority of the fiber reinforcements in the polymer are oriented substantially parallel to an axis passing through the center of the annular ring. A method for making the liner member is also disclosed.

Abstract: A piston of an air compressor, the air compressor including the piston actuated by a motor to move upward and downward in a cylinder. The piston contains a head accommodating an air stop sheet which has a first bending section being a boundary line of an acting area and a positioning zone of the air stop sheet. The acting zone has a noncircular spacing groove configured to separate an external portion and a circular portion, a neck, and a second bending section, such that an axial line between the circular portion and the external portion is the second bending section at an obtuse angle less than 180 degrees, and the second bending section is defined between a bottom of the circular portion and a top of the external portion at an acute angle ?2.

Abstract: Systems and methods for enhancing performance in a reciprocating compressor are described. The compressor includes a cylinder, a crank shaft housing, a crank shaft, a motor, a motor housing and rod assembly. The rod assembly includes a coupling rod portion, a head portion, a cup seal, a cap and one or more valves. The rod assembly is configured to reciprocate within the cylinder so as to compress fluid within a space formed by the cylinder. The rod assembly is driven by the crank shaft. The one or more valves are configured to control air to the compressor. The one or more valves are removably coupled to the head portion, such that the one or more valves remain coupled to the head portion when the cap is detached from the coupling rod assembly.

Abstract: A pump is disclosed having a manifold with an inlet, a pressure outlet, and a return outlet. The pump may also have a jacket connected to an end of the manifold to create an enclosure that is in fluid communication with the inlet of the manifold, and at least one pumping mechanism extending from the manifold into the jacket. The at least one pumping mechanism may have an inlet open to the enclosure and an outlet in communication with the pressure outlet of the manifold. The pump may further have a standpipe extending from the manifold into the enclosure. The standpipe may be in communication with the return outlet of the manifold.

Abstract: A valve of a piston pump, in particular for a hydraulic vehicle brake system, includes a closing body configured to be moved in an axially guided manner against a sealing seat. The closing body is formed in two pieces, which include a damping piston and a closing element inserted in the damping piston.

Abstract: A method of implementing a substitute for a pump-off controller in a downhole production string, the method including locating a pump and a valve in the production string wherein capabilities include the pump pumping a reservoir product through the valve, the valve transitioning to a bypass mode, and the valve interrupting a reservoir product flow.

Abstract: According to one embodiment, there is provide a piston pump, including: a cylinder having a bottomed cylindrical shape; a piston slidable within the cylinder, the cylinder and the piston defining a pressure chamber therebetween; a suction valve unit disposed in a suction passage of the pressure chamber; and a discharge valve unit disposed in a discharge passage of the pressure chamber, wherein the piston includes a cylindrical piston portion and a large diameter piston portion provided to cover one end of the cylindrical piston portion, and wherein the large diameter piston portion includes a working fluid guide groove extending thereinside along the axial direction of the piston.

Abstract: The invention relates to a piston pump for a motor vehicle braking system having a housing section and a piston guided displaceably in the housing section. The invention further has an intake valve having a valve seat arranged on the piston. The valve seat is configured as a circular sealing edge. A spherical valve body of the intake valve seals against the spherical sealing edge.

Abstract: A diaphragm pump for a seat adjusting device comprises a diaphragm and a valve member which define a pump chamber therebetween. An inlet valve and an outlet valve are formed on the valve member. A pressure chamber is in fluid communication with the outlet valve and receives fluid discharged from the pump chamber via the outlet valve. One of the diaphragm and the valve member comprises a valve membrane of a pressure relief valve integrated in the pump. The valve membrane is integrally formed with the one of the diaphragm and the valve member. The valve membrane is moveable between a first configuration in which the valve membrane closes a pressure relief channel and a second configuration in which the valve membrane opens the pressure relief channel to allow fluid to be discharged from the pressure chamber.

Abstract: A sealing structure is provided wherein an annular groove formed in a pump cylinder of a piston pump receives therein a seal ring made of a synthetic resin material and having an inner circumferential surface fluid-tightly contacting an outer circumferential surface of the pump piston and an O-ring arranged on the outer circumferential side of the seal ring and urging the seal ring radially inward. The seal ring is formed at its axial end portions with flange portions for preventing the O-ring from coming off. In the state that the seal ring and the O-ring are fitted in the annular groove, the flange portions do not receive a load from the O-ring, and a surface pressure which the seal ring applies to the outer circumferential surface of the piston at an axial center portion thereof is set to be higher than surface pressures which it applies to the outer circumferential surface of the piston at axial end portions thereof.

Abstract: The invention relates to a pump having a valve through which a fluid can optionally flow. The valve is embodied by a cavity for displaceably guiding a spherical blocking body, and a valve seat that is spatially adapted to the spherical shape of the blocking body. A free space protruding radially outwards from the spherical body is located downstream, directly behind the valve seat, for temporarily receiving the fluid which flows through the valve seat.

Abstract: The invention relates to a one-piece plastic element having an inlet valve cover and an inlet valve seat element for an inlet valve of a piston pump of a hydraulic brake system of a motor vehicle. The inlet valve is designed as a check valve, and the inlet valve cover and the inlet valve seat element are connected to each other by a designed fracture point. The invention further relates to a piston pump having an inlet valve cover and inlet valve seat element made of a one-piece plastic element. The invention further relates to a method for assembling the inlet valve designed as a check valve.

Abstract: A piston pump includes a pump mechanism configured to compress fluid sucked from an inlet port by increasing or decreasing a volume of a pump chamber which faces a front end of a piston by reciprocating the piston housed in a housing, a feed mechanism including a feed ring mounted to an annular groove provided at an outer periphery of the piston and following a motion of the piston, a feed chamber formed between the feed ring and the housing, and a valve portion. The piston pump includes a pressure wall provided at the piston and configured to contact the feed ring to axially move the feed ring, and a restriction portion provided at the feed ring and configured to engage with an outer periphery of the piston at a position approximate to the pressure wall for restricting a radial displacement of the feed ring on the piston.

Abstract: A piston pump assembly includes a first pump having a first cylinder member inserted in a piston hole of a pump housing, and a first piston inserted in the first cylinder member, and a second pump having a second cylinder member inserted in the piston hole, and an annular second piston slidably fitted in an annular groove formed in the outer periphery of the first piston, and also axially slidably inserted in the second cylinder member. The first cylinder member axially presses the second cylinder member, thereby preventing the second cylinder member from being dropped out of the piston hole. The second cylinder member has an annular seal surface in contact with a shoulder surface formed on the inner periphery of the piston hole. Strain-absorbing protrusions are formed on the end of the second cylinder member in abutment with the first cylinder member. The protrusions are compressed when they are pressed by the first cylinder member.

Abstract: The invention relates to a piston pump for conveying a fluid, in particular in a vehicle brake system. The piston pump has a cylinder and a piston movably disposed in the cylinder. A restoring element preloads the piston, and a drive unit for actuates the piston in the cylinder to pump the fluid into a pressure chamber formed in the cylinder. The piston is embodied by a first piston par and a second piston part. The first piston part is a cylindrical body, which can be moved by the drive unit. The second piston part form the piston base, in which four radial inlet openings and one axial connection opening for communication with the pressure chamber are disposed. A flange for the disposition of a seal is disposed on the outer circumference of the piston base element. The openings are simple to make in the face ends and circumferential regions of the second piston part.

Abstract: A supply device for the supply of pressure fluid into at least one vehicle brake or into a pressure fluid accumulator, wherein a piston is movably arranged in an accommodating member, a carrier bears a non-return valve arranged coaxially to the piston for the purpose of ventilating a working chamber into which the piston plunges, and wherein a resetting spring is arranged between the carrier and the piston. A multi-piece cage facilitating inserting the resetting spring into the cage parts, the cage parts comprise a fastener that locks the cage due to relative displacement of the cage parts, and the resetting spring is caged and simultaneously elastically preloaded under the relative displacement of the cage parts.

Abstract: A piston pump for the hydraulic energy supply in a motor vehicle, comprising a piston that is movably arranged in a stepped bore of an accommodating member that is provided with a closure, the piston carries a seat for an elastic sealing element which accommodates the sealing element with axial play, and with radial elastic preload for the purpose of sealing between piston and cylinder. The seat for the sealing element has a structure which generates forces pointing radially towards a piston axis and expanding the sealing element in a radial direction, and that the structure produces an elastic deformation of the sealing element for an increased and dosed sealing contact pressure between piston and cylinder.

Abstract: The invention relates to a piston pump for conveying fluids. The piston pump includes a piston, and a pressure chamber located between an intake valve and a discharge valve. The intake valve is arranged between the pressure chamber and a low-pressure zone of the piston pump. The intake valve has a valve body, a closing element, a device for preloading the closing element, and a device for fastening the intake valve to the piston. The fastening device encompasses at least two fastening elements which protrude from the valve body toward the piston. The fastening elements are positioned at a distance from one another, and are fitted with inlets therebetween for supplying fluid. The invention further relates to a piston pump having an intake valve without a spring-biased element.

Abstract: The present invention relates to a piston pump. A piston with at least one transverse bore and a longitudinal blind bore, has a plate element with an opening, arranged on the piston at an opening of the longitudinal blind bore. The invention includes an inlet valve, an outlet valve, and a pressure chamber arranged between the inlet valve and the outlet valve. The inlet valve has a pretensioning element, a closing element, and a sealing seat, which sealing seat is built on the plate element.

Abstract: An arrangement for dispensing color paste, a shading apparatus, a method, a computer program product, and a memory. The arrangement includes a piston pump including a feed channel. The feed channel is provided with a substantially different amount of color paste per travelling length unit when the piston is moving towards the first end of the cylinder than when the piston is moving towards the second end of the cylinder. The arrangement further includes a valve connected to the feed channel, a dispensing channel connected to a first outlet channel of the valve for conveying color paste into a can, and a by-pass feed channel connected to a second outlet channel of the valve for conveying color paste past the can for the paint to be shaded.

Abstract: A filter to be mounted in a valve seat member for filtering liquid is proposed which can be manufactured without a drawing step, thereby improving productivity and cost performance of a piston pump in which such a filter is mounted. The filter is a flat metal plate including a main body formed with a plurality of filter holes in a central portion thereof, and a plurality of projections integrally and radially outwardly extending from a perimeter of the main body so as to be circumferentially spaced apart from each other. The filter is pushed into a filter mounting hole formed in a valve seat member of a discharge valve in a piston pump with the projections bent toward the opening of the filter mounting hole while being pressed against the inner surface of the filter mounting hole under an elastic restoring force and fixed to the valve seat member.

Abstract: A piston pump having a retaining device for retaining a spring element for restoring a closing element of a valve; the retaining device includes a receiving region for receiving and bracing the spring element and an integrally formed sealing region, in order to seal off a pressure chamber from a low-pressure region of the piston pump.

Abstract: The invention relates to a piston pump which is used to guide a fluid and which comprises a cylinder, a piston which is displacably arranged in the cylinder, a return element for the piston and a drive in order to displace the piston in the cylinder. The cylinder comprises a first area having a first internal diameter and a second area having a second internal diameter. The first internal diameter is greater than the second internal diameter.

Abstract: A piston pump includes a pump housing having a suction port and a discharge port. A piston is mounted in a bore of the pump housing and forms a pump chamber. Suction and discharge valves are provided on the opposite sides of the pump chamber, respectively. The suction valve includes a retainer which is mounted on the piston and has a valve bore which communicates with the suction port, a valve seat which is formed at the pump chamber end of the valve bore, and a valve body holding portion and a spring holding portion. The suction valve also includes a valve body which can seat and unseat from the valve seat and which is received and held by the valve body holding portion, and a spring which is received and held by the spring holding portion and biases the valve body towards the valve seat.

Abstract: The invention relates to a piston pump having a piston assembly including at least one cross bore and a longitudinal bore corresponding to the at least one transverse bore, a cylinder, into which the piston assembly is guided in a longitudinally movable manner, and an inlet valve with a cage element, in which an inlet valve spring and an inlet valve sealing element are disposed, and a corresponding inlet valve seat, which is disposed on the piston assembly. Fluid can be guided through the longitudinal bore into a compression chamber via the inlet valve. A return spring is disposed in the compression chamber for the piston assembly. The invention further relates to an associated braking system. The cage element has a resilient high-pressure sealing element that is configured to receive radially acting power components, and to effect a seal against a cylinder wall via a radial sealing surface, and in order to effect an axial seal against the piston assembly via an axial sealing surface.

Abstract: A piston pump is proposed, having a pump housing, in which housing a pump piston is guided axially movably, so that upon an actuation of the pump piston, a fluid is pumped from an intake side to a compression side, via a pump chamber bordering on the pump piston, the compression side being provided with an outlet valve, which is preceded by a damping element.

Abstract: The invention relates to a supply device for the supply of pressure fluid into at least one vehicle brake or into a pressure fluid accumulator, wherein a piston is movably arranged in an accommodating member, a carrier bears a non-return valve arranged coaxially to the piston for the purpose of ventilating a working chamber into which the piston plunges , and wherein a resetting spring is arranged between the carrier and the piston. It is the essence of the invention that a multi-piece cage allows inserting the resetting Spring into the cage parts, the cage parts comprise fastening means that lock the cage due to relative displacement of the cage parts, and the resetting spring is caged and simultaneously elastically preloaded under the relative displacement of the cage parts.

Abstract: A supply device for the supply of pressure fluid into at least one vehicle brake or into a pressure fluid accumulator, wherein a piston is movably arranged in an accommodating member, a carrier bears a non-return valve arranged coaxially to the piston for the purpose of ventilating a working chamber into which the piston plunges, and wherein a resetting spring is arranged between the carrier and the piston. A multi-piece cage facilitating inserting the resetting spring into the cage parts, the cage parts comprise fastening means that lock the cage due to relative displacement of the cage parts, and the resetting spring is caged and simultaneously elastically preloaded under the relative displacement of the cage parts.

Abstract: A piston pump including a pump housing, a piston provided at the inner bore of the pump housing and assembled with an annular sealing member to form a pump chamber. The piston is configured to slide at an inner wall of the inner bore. The annular sealing member is assembled with the piston so as to slide at the inner wall of the inner bore in the axial direction together with the piston. And a first sliding range of the piston relative to the inner wall of the inner bore and a second sliding range of the annular sealing member relative to the inner wall of the inner bore do not overlap each other in the axial direction.

Abstract: In a liquid pump for a braking system of a vehicle, one end of a piston is slidably inserted into a cylindrical space of a housing member, and a sliding ring is provided on the piston. A suction chamber is formed by an inner peripheral surface of the housing member, an outer peripheral surface of the piston and the sliding ring. An inner diameter “Dk” of the housing member is made larger than an inner diameter “Dc” of the cylindrical space. As a result, the volume of the suction chamber is increased, without making the piston smaller in its diameter.

Abstract: The present invention relates to a piston pump for delivering hydraulic fluid, including a reciprocating piston for building up pressure in a pressure chamber; a sealing element is situated on the piston; during a compression phase, this sealing element produces a seal between the pressure chamber and a low-pressure region of the piston pump and during an intake phase, it opens a connection between the pressure chamber and the low-pressure region in order to draw hydraulic fluid into the pressure chamber.

Abstract: A piston pump includes a first piston pump including a first piston and a first pump chamber, a second piston pump including a second piston and a second pump chamber, the second piston operating to follow the first piston, a pressure release passage formed in communication with the second pump chamber, and a relief valve provided at the pressure release passage and defining an upper limit discharge pressure of the second piston pump. When a discharge pressure of the second piston pump is equal to or smaller than the upper limit, a discharge fluid of the second piston pump is added to that of the first piston pump so as to flow into an outlet port. When the discharge pressure exceeds the upper limit, the discharge fluid is released to the pressure release passage and the discharge fluid of the first piston pump only flows to the outlet port.

Abstract: A piston pump includes a pump mechanism for changing a volume of a pump chamber to move a piston in a housing, and a feed mechanism that has a feed ring attached to a circular groove portion of the piston to be slaved with a movement of the piston. The feed mechanism is located in a suction passage from a suction port to a pump chamber, and the piston has a flange portion protruding radially outwardly. An inner peripheral surface of the feed ring has an inner-diameter enlarged portion extending radially outwardly to have an enlarged passage portion between the inner peripheral surface of the feed ring and the outer peripheral surface of the piston, and a valve portion for opening and closing a suction passage is constructed of an end portion of the inner diameter enlarged portion of the feed ring and the flange portion.

Abstract: A reciprocating pump includes a drive section and a pump section. The drive section has a reciprocating coil assembly to which alternating polarity control signals are applied during operation. A permanent magnet structure of the drive section creates a magnetic flux field which interacts with an electromagnetic field produced during application of the control signals to the coil. Depending upon the polarity of the control signals applied to the coil, the coil is driven in one of two directions of movement. A drive member transfers movement of the coil to a pump element which reciprocates with the coil to draw fluid into a pump chamber and expel the fluid during each pump cycle. The pump is particularly well suited to cyclic pumping applications, such as fuel injection systems for internal combustion engines.

Abstract: A piston pump (10) for a hydraulic consumer of an electronically controlled vehicle brake system, carries a stepped piston (50, 50?) and centers a sealing assembly (26, 26?) which is retained in an axial direction Ax by a step (52, 52?) on the stepped piston (50, 50?), on the one hand, and is retained by a spring cage (53, 53?), on the other hand. The stepped piston (50, 50?) includes a plane support (54, 54?) for plane support legs (55a,b,c; 55a,b,c?) of the spring cage (53, 53?) The stepped piston (50, 50?) includes radially inwards, with respect to the support (54, 54?), a stepped bore (56, 56?), with the bore (56, 56?) accommodating centering legs (57a,b,c; 57a,b,c?) of the spring cage (53, 53?). Coaxially as well as inside the stepped bore (56, 56?), a spring-loaded valve member (59, 59?) of a non-return valve is arranged.

Abstract: A suction valve for reciprocating compressor includes a fixation part, which receives a driving force of a reciprocating motor, and is fixed-combined to the front end surface of a piston performing linear reciprocal movement in the cylinder, a switching part for switching a hollow channel formed to penetrate the piston having a certain area, and a plurality of arms for connecting the switching part and the fixation part to make the switching unit behave in a certain displacement section having the fixation part as a fixed point. Receiving driving force of the reciprocating motor, the piston is bent and straighten by the pressure difference, and stress is distributed evenly in the above process, and minimizing bulking phenomenon to prevent damage of a switching part. Also, the responsiveness of the valve can be improved.

Abstract: A piston pump including a pump housing, a piston provided at the inner bore of the pump housing and assembled with an annular sealing member to form a pump chamber. The piston is configured to slide at an inner wall of the inner bore. The annular sealing member is assembled with the piston so as to slide at the inner wall of the inner bore in the axial direction together with the piston. And a first sliding range of the piston relative to the inner wall of the inner bore and a second sliding range of the annular sealing member relative to the inner wall of the inner bore do not overlap each other in the axial direction.

Abstract: A piston machine includes a cylindrical wall (2) defining a swept volume (1) and having a plurality of gas inlet openings (5), and a piston (3) reciprocating in the swept volume (1), and the piston head (12) of which is formed as a valve having a plurality of openings (14) provided in the piston head (12), and a forcelocking device (16, 21; 18, 24) for retaining the plurality of openings (14) in one of their open condition and closed condition.

Abstract: A high-pressure fluid is continuously generated with high efficiency without causing pulsation of pressure by reciprocally moving a piston having first, second and third chamber sections under the control of an actuator including an operating pressure source and a directional control valve. With the reciprocating motion of the piston, liquid or fluid such as gas is fed into the first, second and third chamber sections in sequence through check valves and finally discharged outside at high pressure. The actuator is operated hydraulically, mechanically or electrically.

Abstract: A pump assembly flows pressurized engine oil to hydraulic injectors in a diesel engine. The assembly includes a high-pressure pump with a bored piston passage. The outer end of the piston bore is closed by a plug assembly pressed in the bore.

Abstract: A suction valve for reciprocating compressor includes a fixation part, which receives a driving force of a reciprocating motor, and is fixed-combined to the front end surface of a piston performing linear reciprocal movement in the cylinder, a switching part for switching a hollow channel formed to penetrate the piston having a certain area, and a plurality of arms for connecting the switching part and the fixation part to make the switching unit behave in a certain displacement section having the fixation part as a fixed point. Receiving driving force of the reciprocating motor, the piston is bent and straighten by the pressure difference, and stress is distributed evenly in the above process, and minimizing bulking phenomenon to prevent damage of a switching part. Also, the responsiveness of the valve can be improved.

Abstract: A piston pump comprises cylinder attached within a cavity of a pump housing. An outlet check valve seat is defined about an outlet of the cylinder. A piston is slidably received in a bore of the cylinder and has a first passageway formed therein. A cylinder head encloses the outlet of the cylinder and defines a second passageway therein. The first passageway has an inlet in fluid communication with the cavity of the pump housing, and an outlet in fluid communication with a pumping chamber defined in the pump housing. A first spring retains the piston to the cylinder. A first check valve member is a ball retained near a valve seat formed in the first passageway of the piston by a disk spring, and allows fluid to flow only from the inlet to the outlet of the piston.

Abstract: In a suction valve apparatus of a reciprocating compressor including a piston having a gas passage at which gas flows inside its body portion, a valve seat formed at an end of a piston body to open the gas passage and a step face formed so as to have a thickness inward from the valve seat and have a plurality of gas through holes and a mounting through hole, and a valve cone having a detachable coupling portion formed extendely from a cone portion corresponded to the valve seat of the piston and inserted into the mounting through hole of the step face of the piston so as to be movable, a re-expansion loss can be reduced by minimizing a dead volume of a suction gas valve, an efficiency of a reciprocating compressor can improve by reducing a heat transmission loss by sucking refrigerant gas through the plurality of gas through holes of the step face from the gas passage.

Abstract: The invention relates to a piston pump for increasing pressure for liquids, in particular for the camshaft phase adjustment of reciprocating internal combustion engines, said piston pump advantageously being integrated into the housing of the cylinder head. The piston pump for increasing pressure is defined in that it increases an existing fluid pressure to a required fluid pressure and keeps this pressure virtually constant. The piston pump for increasing pressure is advantageously pre-assembled in a sleeve.

Abstract: The invention relates to a piston pump for a hydraulic, slip-controlled vehicle brake system. The piston pump has a piston, which is inserted with a part of its length into a sleeve. A tubular filter that encompasses the piston is attached to the sleeve and constitutes a captive retainer, which secures the piston in a captive fashion in the sleeve. In order to reduce an axial mobility of a sealing ring that seals the piston in the pump housing, the invention proposes attaching the filter, which limits the axial mobility of the sealing ring, to the sleeve in an axially mobile fashion.

Abstract: The present invention relates to a piston pump, which is in particular appropriate for the pressure fluid delivery in electronically controlled brake systems, including a housing, a suction valve, a pressure valve, and a pump piston that is designed as a stepped piston having a large-diameter portion and a small-diameter portion. According to the present invention, the stepped piston at its large-diameter portion is guided in a pump cartridge. Preferably, the pressure valve is designed additionally at the cartridge in a radial direction relative to the direction of movement of the stepped piston.

Abstract: The invention relates to a pump of the type comprising a cylindro-conical body (1) defining a metering chamber (10) closed at its bottom portion by an inlet valve (11) and at its top portion by a moving piston (2) co-operating with resilient return means (3) while being carried axially by a nozzle tube (4) having a top end that projects outside the pump body and having a bottom end that is provided with at least one delivery orifice (40), the pump being characterized in that said piston (2) is slidably mounted firstly about the tube (4) between a closure position closing the delivery orifice (40) and an open position in which said orifice is fully open, and secondly in sealed peripheral contact with the inside wall of said chamber (10) between a top end-of-stroke abutment and a bottom end-of-stroke abutment; the coefficient of friction between the piston (2) and the tube (4) being less than the coefficient of friction between said piston (2) and the inside wall of the body (1).

Abstract: A pump and a pump piston assembly. The pump piston assembly includes a pump piston, a pump check valve, and a spring. The pump piston has a piston bore extending from a first piston end toward a second piston end. The pump check valve is positioned proximate the first piston end. The spring has an attached portion attached to the pump piston proximate the first piston end and has a biasing portion biasing the pump check valve to fluidly block the piston bore. The attached portion of the spring is closer to the second piston end than is the biasing portion of the sprint. The pump includes the pump piston assembly and a pump sleeve, wherein the pump piston is slidably engaged in the sleeve bore of the pump sleeve.

Abstract: A valve fastening structure of a reciprocating compressor is provided. The valve fastening structure of the reciprocating compressor includes a piston, which is combined with a moving magnet of a driving motor and is in a linear reciprocating motion inside a cylinder and in which a refrigerant channel is formed in the direction of the reciprocating motion, a suction valve arranged in the leading end of the piston, the suction valve for opening and shutting the refrigerant channel of the piston, and magnets inserted into and fixed to the leading end of the piston, the magnets for fixing the suction valve by magnetic force. It is possible to minimize dead volume in the cylinder and to easily control the stroke of the piston by establishing the suction valve as the cardinal point during the controlling of the stroke of the piston. Accordingly, the efficiency of the compressor is improved.

Abstract: A piston pump for a slip-controlled, hydraulic brake system of a vehicle. A hollow piston is provided with an inner piston seal that has a sealing lip. During an upward reciprocating motion of the piston, fluid can flow past the sealing lip in a direction of a piston inner (displacement chamber) and constitutes an inlet valve of the piston pump. During a downward movement of the piston the sealing lip is forced by pressure against an inner surface of the piston to prevent a flow of fluid past the sealing lip. The invention obviates the need for a separate inlet valve and makes it possible for the piston pump to be short in length.