Abstract: A muffler cover of a compression element has discharge outlets or hole portions that discharge a compressed refrigerant gas into a closed vessel from a compression element. A suction pipe provides refrigerant gas, which can be sucked into the compression element in the closed vessel. The suction pipe is attached to the closed vessel. A first direction and a second direction, which correspond to natural vibration modes of the suction pipe, do not coincide with a direction that connects two hole portions. Therefore, even if the refrigerant gas discharged from the compression element resonates in the closed vessel, vibrations of the suction pipe can be reduced.

Abstract: A rotary compressor includes a rotation compression element, a discharge port and a muffler. The rotation compression element is configured to compress gas as a result of rotation of a crankshaft about a rotation axis. The discharge port is configured to discharge the gas compressed by the rotation compression element. The muffler is arranged to cover the discharge port and surround the crankshaft. The muffler has a muffler crankshaft hole through which the crankshaft passes, and a muffler discharge region configured to discharge the compressed gas discharged from the discharge port toward an outer surface of the crankshaft.

Abstract: A rotary pump includes a stator having a chamber delimited by a circumferential wall, a cylindrical rotor tangent to the circumferential wall of the chamber and suitable for being driven in rotation around an axis eccentric with respect to the chamber, and at least a vane diametrically traversing the rotor by delimiting in the rotor two half shells, mutually separated by the walls guiding the vane. The two half shells are hollow, and inside these hollow half shells are housed elastic leaf springs forming one-way valves with respect to four passageways formed in the half shells; the discharge of the air-oil mixture takes place, after a centrifugation and a partial recycling, through passageways, also in the case of a counter rotation of the pump. This configuration allows a bidirectional use of the same rotor.

Abstract: An electrical submersible well pump assembly having a progressing cavity pump, a pump motor, a flex shaft connecting the pump motor to the pump, and a gas/liquid separator on the inlet to the pump. An inner and outer housing circumscribe a portion of the flex shaft, each having fluid inlets. The fluid inlets on the outer housing are above the inner housing inlets and an annulus is formed between the inner and outer housing. Wellbore fluid enters the assembly through the outer housing inlets, flows downward through the annulus, and into the inner housing inlets. Gas separates from the liquid as the fluid flows downward from the outer housing inlets to the inner housing inlets.

Abstract: An oil rotary vacuum pump of mechanical type (100) is filled with a requested amount of oil at the end of the manufacturing process, then it is stored and then shipped to the user, letting the user to avoid an operation of introducing the proper amount of oil into the pump. The oil leakage is prevented by securing the suction and/or exhaust ports (3, 17) of the pump, which are sealed by means of a removable sealing member, for instance by means of a membrane (21, 23).

Abstract: A compressor apparatus has a housing (22) having first (53) and second (58) ports along a flowpath. One or more working elements (26, 28) cooperate with the housing to define a compression path between suction and discharge locations along the flowpath. A check valve (70) has a valve element having a first condition permitting downstream flow along the flowpath and a second condition blocking a reverse flow. Sound suppressing means (120, 220, 320) at least partially surround the flowpath upstream of the valve element (70).

Abstract: Disclosed herein is a muffler of a scroll compressor. The muffler includes a first muffler having a pair of chambers defined above an outlet of a fixed scroll to communicate with the outlet and a gas passage hole formed at the center of an upper end thereof, and a second muffler located around the first muffler to be spaced apart from the gas passage hole of the first muffler and having a chamber including one or more guidance paths of the fixed scroll. The muffler can achieve reduction of operational noise, sufficient separation of oil contained in discharge gas, and efficient isolation between a discharge pressure inside the muffler and outside suction pressure.

Abstract: A pump, in particular a hydraulic pump for a power steering system, has a housing. The pump is a prefabricated structural unit in which the end faces of the housing are closed by a flange and by a cover, respectively. The flange and the cover are braced against each other by at least one holding part.

Abstract: A projection of an upper bearing member is provided with a porous member, and a lower space between a rotational motor and a compression mechanism is defined into a lower compression mechanism-side space and a lower rotational motor-side space. With this structure, stirring effect of working fluid flowing in the lower compression mechanism-side space caused by rotation of the rotor is suppressed, and oil drops mixed in the working fluid are prevented from being finely divided by the stirring effect, the oil drops are allowed to fall due to the gravity in the lower compression mechanism-side space, and oil separating effect from the working fluid is enhanced.

Abstract: In a two-stage rotary compressor of the present invention, an oil supply hole connecting an oil reservoir on a bottom portion in a closed vessel to a suction port formed in a lower supporting member is provided in the lower supporting member attached to the lower side of a high stage side rotary compressing element, and a necessary amount of oil is supplied into return refrigerant gas sucked into the high stage side rotary compressing element through this oil supply hole. Thus an outer circumferential surface of a roller, which eccentrically rotates in a cylinder, is lubricated to protect it from wear. Additionally, the gas seal properties between an inner circumferential surface of the cylinder and an outer circumferential surface of the roller and between a roller end surface and a partition plate and between a roller end surface and a cylinder end surface, are increased whereby the compression efficiency of the refrigerant gas can be improved.

Abstract: A muffler that is externally mounted to a housing shell of a compressor. To externally mount the muffler to the housing shell and prevent unnecessary vibration of the muffler during compressor operation, an attachment device connects an essentially central portion of the muffler to the housing shell. The attachment device may also be adapted to house a pressure- or temperature-related sensor device.

Abstract: A rotary compressor including upper and lower cylinders constituting first and second rotary compression elements; a lower support member which closes an opening of the lower cylinder and which has a bearing as a bearing portion of a rotation shaft; a discharge muffler chamber formed by depressing an outer surface of the bearing of the lower support member on the side opposite to the lower cylinder to close the depressed portion with a lower cover; an O-ring groove formed in the surface of the bearing which abuts on the lower cover; an O-ring stored in the O-ring groove; and a gasket disposed between the lower support member. The lower cover in an outer peripheral portion of the lower support member, and the surface of the lower cover on the side of the lower support member, is provided with a stepped portion to absorb a thickness of the gasket.

Abstract: In an embodiment, a vacuum pump is capable of preventing adhesion of by-products to its surfaces. The vacuum pump includes a stator. The stator includes a cylinder wall and a pair of diaphragms disposed at opposite ends of the stator. A rotary shaft passes through the diaphragms, and a lobe is attached to the rotary shaft in the stator. The lobe may include a fluid port, and the fluid port may be disposed in sidewalls of the lobe to face the diaphragms. The rotary shaft may include a fluid supply path in communication with the fluid port.

Abstract: A high inner pressure type multistage compression rotary compressor having a support member blocking an opening of a cylinder constituting the rotary compression element and having a bearing of a rotary shaft. The surface of the support member on a side opposite to the cylinder is depressed, and a rib is added to a part of this depressed portion. A discharge muffling chamber formed in the surface of the support member on the side opposite to the cylinder is divided into a plurality of discharge muffling chambers, and the divided discharge muffling chambers are connected to each other by a passage disposed it a blocking plate and/or the rib.

Abstract: A single-stage liquid-ring vacuum pump having a double axial inlet with flat-distribution plates comprises a central body (2), an impeller (5) eccentrically housed in a chamber (4) delimited by the central body (2), a flanged suction manifold (15) in fluid communication with two suction openings (8) located at opposite ends of the central body (2), a flanged exhaust manifold (17) in fluid communication with two exhaust openings (9) located at opposite ends of the central body (2). The flanged suction manifold (15), flanged exhaust manifold (17) and feed manifold are integrated into the central body (2), so as to reduce weights and bulkiness as compared with the pumps of the known art, the pump performance being the same.

Abstract: A scroll fluid machine comprises a housing, a drive shaft, a stationary scroll fixed to the housing, and an orbiting scroll driven by the drive shaft. A gas from the outer circumference of the housing is introduced between the stationary and orbiting scrolls, and sent to the center by revolving the orbiting scroll in engagement with the stationary scroll. On the rear surface of the stationary scroll, there are provided a plurality of cooling fins that radially extend. Between the adjacent cooling fins, a silencer is provided to prevent noise caused by discharge of the gas.

Abstract: A rotary vane compressor having features for reducing sound emitted from the compressor during operation. The sound reduction features include and relate to specific components of the compressor. Specifically the features relate to (1) the compressor motor; (2) a non-vented motor housing and back or closure; (3) the inlet ring; (4) the bearing system; (5) the rotor and vane positioning and vane weight or mass; (6) the mass of the body within which the rotor and vane rotate; and (7) a shroud which surrounds the body which is solid and non-vented solid and may be formed of a laminated material having a sound dampening core layer.

Abstract: A rotary machine is powered by a drive shaft having a bore extending through it. A single piece lubricant flinger is disposed within the bore to form a lubricant pump. The lubricant flinger includes an upper plate located within the bore and a washer located adjacent the opening of the bore. The washer is connected to the upper plate by a connection section and the washer defines an aperture which allows fluid to flow into the bore of the shaft.

Abstract: Inlet piece for a liquid-injected compressor element, characterized in that it comprises a sleeve (8) which consists of a casing (11), a bottom wall (12) provided with an opening (13) and a top wall (14) which is entirely tight, a pipe (9) opening on the inside of the sleeve (8) and a partition (10) comprising a span part (15) which spans the opening (13) in the aforesaid bottom wall (12) and which transforms into an inclosing part (16) reaching down to the bottom wall (13), whereby the partition (10) leaves a passage (18) on one side of the opening (13) and the pipe (9) opens in the sleeve (8) between the top wall (14) and the span part (15), such that, because of the partition (10), gas flowing from the opening (13) to the pipe (9) has to make among others a revolving movement.

Abstract: A scroll fluid machine comprises a housing, a driving shaft, a fixed scroll fixed to the housing, and an orbiting scroll. A gas introduced from the outer circumference of the housing is compressed towards the center of the housing with revolution of the orbiting scroll by the driving shaft. The compressed gas is discharged through a discharge hole extending from the center outward in a radial direction. A silencer fits in the discharge hole to prevent noise caused by discharge of the gas.

Abstract: A rotary vane pump has an open ended pump cylinder mounting a drive motor at one end and a ported end plate and sound chamber at the other end. The cylinder contains a rotor mounted to an eccentric drive shaft and having vane grooves receiving slidable vanes contacting an inner diameter of the cylinder. The end plate has an outlet port and primary and secondary inlet ports in communication with the cylinder interior, the inlet ports being in communication with an area of net expansion. The sound chamber has an intake port and an exhaust port in communication with the respective outlet and primary and secondary inlet ports of the end plate. The sound chamber is partitioned to define a number of internal cavities through which the incoming air is routed to the secondary inlet port.

Abstract: A rotary vane pump has an open ended pump cylinder mounting a drive motor at one end and a ported end plate and sound chamber at the other end. The cylinder contains a rotor mounted to an eccentric drive shaft and having vane grooves receiving slidable vanes contacting an inner diameter of the cylinder. The end plate has an outlet port and primary and secondary inlet ports in communication with the cylinder interior, the inlet ports being in communication with an area of net expansion. The sound chamber has an intake port and an exhaust port in communication with the respective outlet and primary and secondary inlet ports of the end plate. The sound chamber is partitioned to define a number of internal cavities through which the incoming air is routed to the secondary inlet port.

Abstract: The invention relates to a feed pump for fluidic media, comprising a displacement body that is mounted in a pump housing and equipped with slide bearings and connecting channels that connect the slide bearings to the produce channel on the suction side for recirculating the fed medium that lubricates the slide bearings. The connecting channels are linked to control channels that lead to the exterior and guide channels are provided in the extension of the connecting channels in the housing of the cover. Said guide channels accommodate the valve plungers, each of which has a constriction. The section of the valve plunger lying adjacent to the product channel has a length and a diameter, which correspond to the length and diameter of the connecting channel.

Abstract: A gerotor motor including a brake package, and a method for setting the load holding torque of the brake package. The endcap assembly (21) defines a set of internal threads (85) disposed adjacent a brake package piston member (75). An enclosure member (87) defines a spring seat (115) for a set of Belleville washers (105), and defines a set of external threads (88) engaging the internal threads (85). Upon assembly of the motor and brake package, a resistance load is applied to a motor output shaft (43) corresponding to a desired load holding torque. The motor is pressurized sufficiently to rotate the output shaft in opposition to the resistance load. The enclosure member (87) is rotated so that it moves axially in a direction to increase the bias preload on the Belleville washers (105) until the output shaft (43) no longer rotates.

Abstract: A discharge pulsation reducing cooler B is provided to cover the circumferential periphery of a compressor A. The discharge pulsation reducing cooler B has a delivery passage 41 and a jacket 43 covering that, and cooling water is circulated through a passage formed between the delivery passage 41 and the jacket 43. Delivered air flowing through the delivery passage 41 is cooled by the cooling water. In particular, because heat exchange efficiency is promoted by turbulence caused by the pulsation in the delivery passage 41, the delivered air is cooled efficiently. Also, pulsation is reduced in first and second expansion chambers 44, 45 in the delivery passage 41, and pulsation noise in the delivery passage 41 is reduced by the cooling water passage 42 and the jacket 43.

Abstract: A hydraulic pump assembly includes a pump housing having a chamber defined therein, wherein the chamber includes a pair of cylindrically shaped portions each defining at least one end wall. The hydraulic pump assembly also includes a pair of rotary pump elements disposed for rotation within the cylindrically shaped portions of the chamber, and which cooperate to create a hydraulic pressure. The hydraulic pump assembly further includes a pair of cylindrically shaped shafts each having at least one end wall, and disposed within the pair of cylindrically shaped portions of the chamber and within the pair of pump elements. The shafts are fixed for rotation and are axially shiftable with respect to the pump elements. A hydraulic fluid within the chamber stabilizes at least one of the axially shiftable shafts such that the end face of the shaft is spaced from the end wall of the cylindrically shaped portion of the chamber when the hydraulic pump is in use.

Abstract: A screw compressor including a housing containing at least one rotor for generating a discharge flow in a discharge direction; a diffuser member communicated with the housing to receive the discharge flow, the diffuser extending from the housing in the discharge flow direction, the diffuser having a converging collecting section, a diffuser throat downstream of the collecting section and a diffusing section downstream of the throat, whereby the discharge flow can be collected and diffused in the discharge flow direction.

Abstract: The invention relates to a system for delivering elastomeric media, the system consisting of a gear pump (1) and a screw-type extruder (10) which, viewed in the delivery direction (6) of the pumping medium, is arranged in front of the gear pump (1) and which consists of a screw (11) and of a screw casing (12).

Abstract: A scroll compressor including a housing having a compression mechanism and a motor disposed therein, rotatively coupled by a drive shaft. A crankcase is disposed in the housing and supports the compression mechanism. A brake element is operatively engaged with the crankcase with at least one roller located therebetween. The roller has a first position relative to the brake element and the crankcase when the compressor operated in a forward direction, in which forward motion of the orbiting scroll member is unimpeded. At the onset of reverse rotation, the roller has an assumed second position relative to one of the brake element and the crankcase, in which the roller is in binding engagement with the brake element and the crankcase to arrest reverse motion of the orbiting scroll member.

Abstract: A gear pump for the power steering of a motor vehicle is integrated into the housing of the drive unit and is surrounded by both the discharge space and the intake space, which extend over the entire length of the housing Ribs are provided in the discharge space for pulsation damping and for stabilization of the pressure field. A filter space is provided between the cover and a filter cap.

Abstract: The drive gear 19, 21 and the synchronizing gear 25, 27 for the two rotors 9,11 of a screw compressor are both located at the pressurized end of the rotor housing 3. At the suction end of the rotor housing 3 is only the bearing 53 for the suction side shaft journal 55, 57 that is free of oil lubrication. Inlet openings 13 in a suction side inlet housing are located in such a way that the intake air cools the oil-free shaft bearing 53. Each shaft journal has a tool interface 63 accessible through the inlet housing on which to attach a rotating tool. The inlet housing 4 can be removed from the shaft journal 55, 57 together with the bearing 53 and seal 87, for example to exchange the bearing, without having to remove the rotors 9, 11 or without throwing off their adjustment.

Abstract: A scroll compressor has a non-orbiting scroll axially secured within an end cap. The compressor is of the sort wherein the back pressure chamber is defined behind the orbiting scroll. In one embodiment a spring biases the non-orbiting scroll toward the orbiting scroll. In other embodiments the non-orbiting scroll is force fit within the end cap.

Abstract: A scroll machine is provided with a muffler mounted to the fixed scroll of the scroll machine for improved sound attenuation.

Abstract: The gear unit for a delivery pump installed in a deep borehole has a toothed gear unit with a pinion located on input shaft (2) and a gear wheel engaged with the pinion, which gear wheel is located on a vertical output shaft (5) driving the delivery pump. The gear unit is designed as a right-angle unit with a conical pinion gear (3) located on the input shaft (2) and a bevel gear (6) located on the output shaft (5). Located on the input shaft (2) is a gearwheel (10) which together with a second gearwheel (11) forms a gear pump which conveys fluid in a direction opposite the operational direction of rotation of the gear unit.

Abstract: A low noise scroll compressor assembly has an orbiting scroll supported for movement about an axis, and a non-orbiting scroll mounted to the crankcase housing along the axis. The non-orbiting scroll is mounted to the crankcase housing by at least one guide bushing that allows axial movement of the non-orbiting scroll relative to the orbiting scroll. A plurality of openings are arranged radially within mounting flanges projecting outward from the non-orbiting scroll. Each opening includes a guide bushing and a dampening bushing. The dampening bushing comprises a material that will absorb an impact force between the non-orbiting scroll and the guide bushing. Absorption of impact forces by the dampening bushing prevents the transmission of vibrations, thereby minimizing or preventing noise.

Abstract: An improved scroll compressor having an axially movable non-orbiting scroll eliminates the need for a separator plate. With the elimination of the separator plate, a back pressure chamber is provided to resist the discharge pressure which will be directed against a rear face of the non-orbiting scroll. In other embodiments, a seal on the rear of the non-orbiting scroll contacts the inner periphery of the end cap. Various ways of increasing the discharge pressure volume, or eliminating undesirable noise are also disclosed. Further, several ways of connecting the end cap to the center shell are also disclosed.

Abstract: A fluid machine includes: a casing having an operating chamber provided in the casing; a pair of rotors rotatably mounted in the operating chamber which have each rotor shaft in each axial direction; an intake opening and discharge opening for fluid and are connected with the operating chamber, respectively; and silencing means provided in at least one of an existing space forming fluid channel on the intake opening side and an existing space forming a fluid channel on the discharge opening side. In the structure, the existing spaces are located between the intake opening and the operating chamber and between the discharge opening and the operating chamber, respectively. Furthermore, at least one among the intake opening and the discharge opening of the fluid where the silencing means is disposed is provided so as to be at parallel with the rotor shafts.

Abstract: Rotary compressor including a main bearing having a discharge passage for discharging compressed gas and a boss for inserting a motor shaft, the main bearing forming a component of a compression chamber, and a muffler having a boss hole for passing the boss of the main bearing and a discharge opening for discharging the compressed gas, the muffler mounted on the main bearing, wherein the discharge opening in the muffler is formed at least one in number inside of the discharge passage in the main bearing, whereby attenuating a noise generated in operation of the rotary compressor, effectively.

Abstract: A scroll machine is provided with a muffler mounted to the fixed scroll of the scroll machine for improved sound attenuation.

Abstract: The present invention relates to a hermetic rotary compressor. More particularly, since the conventional rotary compressor has problems that the effect of a surge recess for reducing noises due to pressure pulsation is insufficient, and it is impossible to obtain the maximum compression efficiency, the present invention is constructed such that noises due to pressure pulsation can be reduced to the maximum and at the same time the compressive driving force required for compressing gaseous refrigerant is decreased to thereby improve the compression efficiency.

Abstract: A scroll machine is provided with a muffler mounted to the fixed scroll of the scroll machine for improved sound attenuation.

Abstract: An apparatus (30) for use in pumping hydraulic fluid includes a pump unit (32) which is driven by an electric motor (34). The electric motor (34) is mounted on a tubular stem (108) which extends axially outward from a manifold plate (44). A stator (100) of the electric motor (34) is fixedly connected with the tubular stem (108). A rotor (112) of the electric motor (34) encloses the stator (100). A hydraulic muffler (50) attenuates noise produced by the gear pump unit (32). The hydraulic muffler (50) includes a channel (58) which extends into the manifold plate (44) from a major side surface (63) of the manifold plate. To increase the ability of the hydraulic muffler (50) to attenuate noise, one or two compliant elements (152 or 166 and 168) are connected with the channel (58).

Abstract: An improved housing for scroll compressor has the end cap housing formed integrally with the fixed scroll member. The end cap housing is preferably welded to a tubular housing enclosing the scroll compressor. Most preferably, the end housing has inner and outer tubular portions and the tubular housing extends upwardly into a channel between the inner and outer tubular portions. A muffler is preferably formed integrally with the end cap and extends to a side of the end cap. The present invention further includes heat transfer fins extending from the end cap. The positioning of the muffler to the side decreases the overall length of the compressor. The use of the fins increases the efficiency of compression as heat is removed from the compression chambers. The use of the unique combined end cap and fixed scroll which is welded to the tubular housing simplifies assembly.

Abstract: A sealed compressor has a sealed casing in which a motor section and a compression section are both accommodated, and also has a pipe connector including at least one sleeve. The sleeve has a first end and a second end opposite to each other. The first end is inserted into a sleeve insertion hole defined in the compression section to allow a refrigerant to flow therethrough, while the second end is hermetically brazed to a copper pipe disposed outside the sealed casing. The sleeve is formed by deep-drawing a copper-plated steel plate into a generally cylindrical shape.

Abstract: An integral oil pump for an apparatus having a plurality of bearings, the oil pump comprising a housing with an opening for a shaft, a cavity within the housing, a ring gear encircling the shaft with clearance between the shaft and an inner surface of the ring gear, a plurality of evenly spaced keyways in the inner surface or the ring gear, a plurality of protrusions extending from the shaft that fit into the keyways to rotate the ring gear when the shaft is rotated, a floating gear meshing with the ring gear, the cavity enclosing the gears with very little clearance between the cavity and the gears, an inlet portion of the cavity adjacent the area where the gears mesh, an outlet portion of the cavity adjacent the area on the other side of where the gears mesh, an inlet port in fluid communication with the inlet portion of the cavity and an oil reservoir, an outlet port in fluid communication with the outlet portion of the cavity and with the bearings to supply pressurized oil to the bearings.

Abstract: An integral brake assembly for a gerotor motor of the type including valving (41) disposed forwardly of the gerotor gear set (15). Orbital and rotational movement of the gerotor star member (31) is transmitted to an output shaft (43) by a main drive shaft (51), which includes a rearwardly extending brake portion (107). The motor includes an endcap assembly (21) defining a brake chamber (73) into which the brake portion (107) extends. A cylindrical brake member (91) is disposed in the brake chamber (73), and includes a circular surface (109) for frictional engagement with a lock piston (75). The brake member (91) also includes a forward generally annular surface (115) for frictional engagement with either the gerotor gear set (15) or an adjacent wear plate (89). The invention at least reduces the need for expensive friction discs in order to achieve a desired level of brake torque, and also utilizes inherent friction in various brake parts for some of the required brake torque.

Abstract: A liquid-injected compressor with at least two cooperating compressor elements (2 and 3) is provided. The compressor elements are mounted in a housing (1). At least one of the compressor elements is rotatable and is bearing-mounted with a shaft end (7, 8, 13, 14) in the housing (1). The compressor is provided with an inlet (22) and an outlet (17-18-19) which are connected to the inside of the housing (1). The shaft end (14) of the rotatable compressor element (3) is situated in the outlet (17-18-19) in the housing (1). At least one body (20 or 41), made of material which is permeable to gas, is fixed on this shaft (14), forming a filter which practically entirely seals the outlet (17-18-19) and only lets the compressed gas through.

Abstract: A scroll-type fluid displacement apparatus including at least two scroll members, with each scroll member having a plate and spiral involute extending from the plate. The spiral involutes mesh to define fluid voids between the scroll members that become smaller towards the center of the scroll members. The apparatus also includes an eccentric crank mechanism having an elongated shaft with an eccentric portion. The elongated shaft is connected at one end to a motor and at another end to a machine, while the eccentric portion is rotatably received by one of the scroll members such that the scroll members will orbit with respect to one another as the shaft is turned by the motor. The apparatus also includes at least one eccentric guide for assisting the eccentric crank mechanism in retaining the scroll members in an orbiting relationship.

Abstract: A hermetic rotary compressor includes a sealed case, an electrically-driven mechanism installed in the sealed case and a compressing mechanism for compressing the sucked-in refrigerant. The compressing mechanism has a cylinder defining a compression chamber into which an eccentric roller of the electrically-driven mechanism is accommodated. Upper and lower flanges are respectively fixed to upper and lower portions of the cylinder so as to support the rotary shaft and seal the compression chamber. At least one resonance chamber is formed at an inner peripheral surface of a discharge port formed in the upper flange, whereby the resonance chamber communicates with the discharge port. A closure member is provided for opening/closing the resonance chamber. The closure member is biased closed by a spring disposed in a hole formed at the inner peripheral surface of the discharge port of the upper flange, the hole and resonance chamber having a common entrance.

Abstract: A fuel pump comprises a pump unit and a motor unit. The pump unit is a trochoid gear type having rotors in a pump chamber defined by a pair of side plates and a cylindrical housing. A disk plate is attached to the side plate to provide an arcuate-shaped pressure pulsation reducing passage jointly with the side plate. Protrusions or recesses are provided in the passage to cause turbulence in fuel flowing through the passage. This turbulence scatters pressure pulsation in the fuel thereby to reduce the pressure pulsation.