Abstract: The cam surface of a roller-type positive displacement pump providing an inlet port and two outlet ports has on circumferentially opposite sides of at least one of the outlet ports a profile such that the difference between the squares of the radii at the instantaneous points of contact therewith of the two rollers which serve to seal the port at said opposite sides is a constant. The portions of the cam surface at oposite sides of such an outlet port have radii relative to the axis of rotation of the rotor which decrease progressively in the direction of rotation of the rotor.

Abstract: A two-shaft vacuum pump which draws gas in at an inlet and compresses it at a first outlet for discharge, thereby producing a vacuum at the inlet, has a second, pressure-responsive outlet from the area where the gas is compressed for discharge from the first outlet. The second outlet thereby relieves excess, compression gas pressure which could overload the pump motor, for example, at the start of operation when high-density gas is drawn in for compression.

Abstract: A lubrication scavenge system for an engine bearing compartment or the like utilizing a gear pump with two or more independent inlets with separate flow paths through the pump. The inlets and flow paths are maintained separate from each other by the use of inlet and discharge seal arcs to avoid any fluid communication therebetween. The pump can operate to pump different fluids through each inlet with the fluid being either a gas or liquid or a mixture of both and with the pump continuing its pumping action when there is an instantaneous interchange in the fluid being pumped at each inlet as can occur when the engine bearing compartment is subjected to varying positive and negative gravity forces.

Abstract: Efficiency of a scroll type compressor or pump having interfitting, generally spiralled vanes is achieved by disposing passages in the outer wraps of the vanes in proximity to the radially outer ends of the vanes.

Abstract: A variable volume ratio screw compressor has a side load inlet port for the injection of refrigerant vapor into the interlobe volume. In order to improve efficiency, overcompression and undercompression are avoided by varying the location of the radial discharge port to give the compressor an internal volume ratio matched to the pressure of the system in which the compressor operates. This is accomplished in the present application by locating a pressure sensing port no earlier than and preferably later in the compression than the side load injection port, but early enough in the compression that it will not communicate with the discharge port. The pressure that is sensed in the sensing port is used to predict the actual peak pressure in order that maximum efficiency may be obtained as a result of matching the internal volume ratio to the pressure ratio of the system.

Abstract: A two stage mixing gear pump for dispersing a gas into a liquid wherein a metered quantity of liquid from the first stage of the pump is supplied to gas filled intertooth spaces of the second stage pump. The gas is introduced into the intertooth spaces of the second stage of the pump through a gas inlet which is adjacent the low pressure side of the gear teeth meshing zone of the second stage of the pump and the liquid enters the gas containing intertooth spaces downstream of the gas inlet.

Abstract: A rotary pump for pumping liquid which includes a rotor combination in the form of a vane pump or gear and rotor with pumping chambers disposed circumferentially around the rotor. The chambers progressively increase in the inlet area and ensmall in the outlet area. Resilient means are interposed between the ensmalling chambers and an outlet to block backflow of the pressurized outlet liquid into pumping chambers containing vaporized liquid instead of solid liquid, thus reducing the pump noise under conditions of vaporization termed "cavitation".

Abstract: A rotary pump for pumping liquid which includes a rotor combination in the form of a vane pump or gear and rotor with pumping chambers disposed circumferentially around the rotor. The chambers progressively increase in the inlet area and ensmall in the outlet area. Pulse absorbtion means are interposed in the fuel passage means to absorb pulses and smooth out the pressurized outlet liquid, thus reducing the pump noise under all conditions of operations.

Abstract: A screw pump of the kind including a screw array consisting of a central screw (1) with convex flanks and one or more side screws (2) with concave flanks, the threads being formed such that coacting screws seal against each other with the screw array being sealingly surrounded by a screw housing (3), so that at least one closed chamber is formed by the sides and roots of the threads as well as the screw housing, the chamber migrating axially from the inlet end of the screw array to its outlet end when the screws are turned, and is in communication at least during a portion of its migration with a pressure fluid source (9) via at least one duct (14) made in the pump. To prevent the occurrence of, and to eliminate, existing air and gas bubbles in the liquid chamber without efficiency being unnecessarily deteriorated, the pump is provided with a regulating device (15) coacting with the duct for adjusting the quantity of liquid flowing to the chamber from the pressure fluid source.

Abstract: A sliding vane type rotary compressor has at least two suction ports through which a refrigerant is sucked into the vane chamber. A combination of a spring made of a shape memory alloy adapted to expand and contract when supplied with an electric current and a spool operative by the spring is disposed in a flow passage through which the source of the refrigerant is connected to one of the suction ports leading to a region of higher magnitude of compression. The flow passage is opened and closed by the spool which is moved by the expansion and contraction of the spring of the shape memory alloy in response to the heat produced by the self heat build-up action when supplied with an electric current and also to the cooling function of the refrigerant of low temperature, thus attaining a variable capacity control of the compressor with a simple and compact construction.

Abstract: A fluid pressure responsive member is shifted in accordance with the pressure differential between two lines either one of which can be a suction line with the other line being a discharge line of a reversible compressor. The fluid pressure responsive member has an arcuate recess formed therein which serves as a secondary suction port which provides fluid communication to the offset cylindrical chamber from the suction line in accordance with the position of the fluid pressure responsive member. Because the porting is responsive to the pressure differential between the two lines, the changeover of the porting is automatic upon the reversal of the operation of the compressor.

Abstract: A fluid pressure responsive member is shifted in accordance with the pressure differential between two lines either one of which can be a suction line with the other line being a discharge line of a reversible compressor. The fluid pressure responsive member has a pair of arcuate recesses formed therein which serve as secondary suction ports which provide fluid communication to the elliptical chamber from suction lines in accordance with the position of the fluid pressure responsive member. Because the porting is responsive to the pressure differential between the two lines, the changeover of the porting is automatic upon the reversal of the operation of the compressor.

Abstract: A rotary vane air or gas motor is provided with a primary exhaust port having an exhaust fluid throttling valve therein for controlling motor speed. The motor includes a secondary exhaust port for discharging exhaust fluid flow from the motor expansible chambers after cutoff of the primary exhaust port. A flow sensing vane member is movably disposed in a flow passage in communication with the secondary exhaust port and is responsive to flow variations to actuate the exhaust fluid throttling valve by connecting linkage. The interconnected exhaust fluid throttling valve and flow sensing vane function as a motor speed limiting governor.

Abstract: A vertical axis hermetic compressor includes an inner cylindrical housing fixed internally of a sealed outer enclosure bearing paired helical screw rotors defining with the inner housing closed thread compressor compression chambers. An electrical drive motor overlies the rotors and is shaft connected to one of the rotors. Compressed refrigerant vapor, where refrigerant is the working fluid, discharges through the motor rotor. A deflector within the top of the outer enclosure such that oil impacted by gas flow discharging axially from the motor adheres to the deflector to provide oil separation.

Abstract: A compressor of the present invention performs restraining action in refrigerative ability at high speed driving time utilizing suction loss that vane chamber pressure drops lower than supply source pressure of refrigerant, and comprises a rotor (14) having vanes provided slidably, a cylinder (11) receiving said rotor (14) and vanes (12), side plates fixed to both side faces of said cylinder (11) and closing tightly a space of vane chamber (18a), (18b) formed by said vanes (12), rotor (14) and cylinder (11) at its side faces, and at least more than two suction ports (15) and (17), whereby even in a compressor having many numbers of vane (12), such a compressor with ability control that having no loss in refrigerative ability at low speed, and refrigerative ability is restrained only at high speed driving can be realized.

Abstract: A rotary pump for pumping liquid which includes a rotor combination in the form of a vane pump or gear and rotor with pumping chambers disposed circumferentially around the rotor. The chambers progressively increase in the inlet area and ensmall in the outlet area. Resilient means are interposed between the ensmalling chambers and an outlet to block backflow of the pressurized outlet liquid into pumping chambers containing vaporized liquid instead of solid liquid, thus reducing the pump noise under conditions of vaporization termed "cavitation".

Abstract: An improved pump assembly includes a plurality of pumping elements which rotate with a rotor and engage an inner surface of a cam ring to define pumping chambers which hold liquid and/or air. As the pumping chambers move along an inlet arc, liquid flows through an orifice to the chambers. The orifice restricts the rate of flow of liquid to the pumping chambers to a flow rate which is insufficient to fill the chambers with liquid during high speed rotation of the rotor. As the pumping chambers move along an outlet arc which has a constant slope toward the rotor, the volume of each pumping chamber is decreased. When the fluid pressure in the pumping chamber exceeds a pump discharge pressure, one of a series of a check valves opens and fluid is discharged from the pumping chamber.

Abstract: A multi-cylinder single-stage rotary rolling piston type gas compressor comprises four modular cylinder housings, partitions and end covers bolted together in end-to-end arrangement. Each cylinder housing includes an inner wall which defines a centrally located cylinder chamber and vane slot and an outer wall which defines a suction chamber, a discharge chamber and an oil chamber or reservoir surrounding the cylinder chamber. The four suction chambers are connected together end-to-end to a common gas inlet port. The four discharge chambers are connected together end-to-end to a common gas discharge port. The four oil chambers are connected together end-to-end. An internally lubricated rotor assembly extends axially through the four cylinder chambers and comprises a shaft rotatably supported on the end covers. The shaft has four eccentric crankarms on which four roller pistons are rotatably mounted, one for each cylinder chamber. The two central pistons are angularly displaced 180.degree.

Abstract: A sealing chamber is defined between the front head and the front side block, and an oil chamber between the rear side block and a partition member secured to the rear end face of the rear side block, respectively. The drive shaft, on which the rotor is rigidly fitted, is radially supported by a pair of roller bearings provided at the front and rear side blocks. The bearings have end portions remote from the rotor enclosedly disposed in the sealing chamber and the oil chamber. The lubricating oil feeding system includes lubricating oil feeding bores formed in the front and rear side blocks and communicating with a zone under discharge pressure, and clearances between the front and rear side blocks and opposed end faces of the rotor. The clearances have predetermined flow resistance, and communicate, on one hand, with the back pressure chamber formed within the rotor, and on the other hand, with the sealing chamber and the oil chamber by way of the above roller bearings.

Abstract: A gerotor type star and ring gear machine in which control orifices in the star gear alternatively register with ports in the end wall. The star gear is formed from a series of plates and has two sets of control orifices formed therein with one set being diametrically opposed to the second set.

Abstract: A vane compressor has a suction connector and a discharge connector arranged at a rear portion thereof. A rear suction chamber is formed at a rear side of the rear side block and communicates with pump working chambers. A passage means directly communicates the above rear suction chamber with an annular front suction chamber formed in the front head in a manner surrounding a sealing chamber accommodating a shaft-seal means.

Abstract: A sealing chamber is defined between the front head and the front side block. The drive shaft on which the rotor is rigidly fitted is journalled by front and rear plain bearings provided on the front and rear side blocks, respectively. The bearing on the front side has an end portion remote from the rotor enclosedly disposed in the sealing chamber. The sealing chamber communicates in a direct manner with the suction port formed in the compressor casing by way of a passage means so as to be supplied in a direct manner with suction refrigerant having a low temperature and a low pressure.

Abstract: A self priming gear pump 14 for pumping liquids containing gases is provided with a vent pipe 26 for releasing entrapped gases that would otherwise collect at the outlet side of the pump 14. The vent pipe 26 terminates within the pump housing 21 at a zone which is out of the path of the oil centrifuged by the gears 25 and in the region lying near the point of intersection of the gears 25. An additional inlet pipe 27 which directs liquid across the main inlet into the gap between the periphery of one of the gears 25 and the housing 21 may be provided to improve liquid sealing.

Abstract: The front and rear side blocks are each formed therein with a first lubricating oil passage which supplies high pressure lubricating oil, and at least one of the side blocks is formed therein with a second lubricating oil passage communicating with the back pressure chamber formed within the rotor. The first and second lubricating oil passages each open at one end in the sliding peripheral surface of a plane bearing formed with the corresponding side block. The drive shaft has its interior formed with a lubricating oil chamber and its peripheral wall formed with at least one lubricating oil feeding hole communicating with the lubricating oil chamber.

Abstract: A hollow housing is provided having opposite ends and defining a cavity within the housing including two slightly greater than one-half cylindrical portions opening toward and into each other and defining a pair of opposite lobes projecting inwardly of opposite sides of the cavity. The opposite ends of the housing are closed by spaced apart end walls between which the cavity is defined and a cylindrical rotor is journalled in the cavity for rotation about an axis at least substantially lying upon a straight line extending between the lobes and with the axis spaced equal distances from the lobes substantially equaling the radius of curvature of the rotor. The rotor has a central cavity therein spaced inward of the outer periphery of the rotor and three substantially equally angularly spaced and generally radial slots are formed in the rotor and extend axially therethrough with the inner ends of the slots opening into the cavity.

Abstract: A gear pump having an annular internal tooth gear and an external tooth gear eccentrically rotative therein is provided with a choke bore at the inlet side of the pump and a series of outlet pressure bores. The outlet bores are valved with individual check valves so as to pass pressure oil from the pressure pockets between the relatively moving gear teeth which pockets diminish in volume at the outlet side of the pump as the teeth move therepast and the pressure pockets discharge into the outlet bores. Where a pocket is insufficiently filled to effect the pressure needed for opening the first valves moved pass by the pressure pockets, the pressure increases with continued rotation as pocket volume decreases. The increase in pressure in the pockets with volume reduction ultimately opens an outlet bore valve to effect discharge to a common high pressure chamber.

Abstract: A pump of vane type which sucks in and discharges fluid includes a pump body which is provided with at least two sets of intake ports and discharge ports, which communicate with a low pressure chamber and a high pressure chamber, respectively. An intake port and a discharge port of each set is spaced apart in substantial coincidence with a spacing between a pair of adjacent vanes, and an intake port (or a discharge port) of a second set is located between an intake port and a discharge port of a first set. Means is provided which controls the communication between selected intake ports and the low pressure chamber and between selected discharge ports and the high pressure chamber.

Abstract: A rotary fluid motor with an internal liner has an internal manifold system within the casing and liner which provides not only separations for the fluid involved, but cooling fins and a structural support for the liner. The function of the internal manifold is to provide cooling fins which is important for adequate cooling of the motor during operating.

Abstract: A rotary compressor including a housing having therethrough a cylindrical bore, end plates attached to the housing to close the open axial ends of the bore respectively, an eccentric rotor rotatable in the bore and vanes slidably mounted in the rotor. A working chamber defined between the adjacent pair of vanes communicates with a discharge chamber outside of the housing through a discharge opening in the wall of the housing. First and second passages have their respective one ends opening to the cylindrical bore and the respective other ends communicating with the discharge chamber. The one end of the first passage is positioned at a location or adjacent thereto where the leading one of the adjacent pair of vanes is positioned when the working chamber defined therebetween has its volume starting to decrease.

Abstract: The pump comprises a pump stator (5), an electric motor stator (4), and a rotor (6) that constitutes the rotor both of the pump and of the electric motor. The pump stator comprises a tubular non-magnetic lining to the electric motor stator, and the rotor is mounted excentrically inside said tubular lining and is equipped with radially movable vanes (63) that co-operate with said lining to provide pumping action when the rotor rotates. The arrangement is particularly applicable to oil-sealed vacuum pumps, and has the advantage of being more compact than units of similar performance, but equipped with a pump and a motor that are separate and interconnected by a mechanical coupling, as is conventional practice.

Abstract: A system for supplying fuel to an atomization fuel oil burner nozzle from a fuel pump at a rate less than that rated for the nozzle for burning of less fuel while achieving good combustion. The fuel is delivered to the nozzle at a pulsing frequency which is dynamically matched to intermittent pressure pulses within the fuel pump to create resonant pressure peaks at the nozzle. The fuel pump creates a pressure pulse each time a tooth of one gear of the pump makes full penetration into the space between a pair of teeth of a coacting rotatable ring gear. Rotatable valving structure, including gear ports in the rotatable ring gear pulses fluid flow to the nozzle by alternately connecting a fluid outlet of the pump to either a pressure port within the pump at the time of a pressure pulse or to the fuel pump inlet with the pressure peak of the pulsed flow being phased together with said pressure pulse.

Abstract: A gas compressor of the scroll type is disclosed wherein means are provided for reducing its degree of compression as it starts from a standing start in order to reduce the initial starting torque required. To this end, passage means are provided which extend through the end plate means of the compressor from a location in communication with the closed moving volumes defined between the wrap elements to a second location in communication with working gas normally at discharge pressure during operation of the compressor. Valve means are associated with the passage means for permitting flow therethrough when the pressure within the closed moving volumes exceeds the discharge pressure at said second location as the compressor starts from a standing start, and for blocking flow therethrough during operation of the compressor when discharge pressure normally exceeds the pressure in the closed moving volumes.

Abstract: A passage leads from a high pressure discharge zone of a vane pump to an interface defined between the surface of the rotor of the pump and an arcuate contact surface formed in the inner wall of the pump housing to supply fluid under pressure to the interface for lubricating same.

Abstract: Control apparatus for purging the pressure in conduits or hoses of pressurized gas/liquid systems such as hot melt foam generating equipment. The control includes a selectively actuable "purge valve" which upon actuation applies an output pressure to reverse the direction of rotation of the motor driving the gas/liquid mixing pump, or alternatively to operate a diverter valve that connects the pump outlet side back to the liquid supply line. Simultaneously, the purge valve cuts off the supply of gas to the mixing pump. The control desirably also includes a selectively actuable "start-up valve" for supplying gas to the gas/liquid mixing pump at higher than normal operating pressure, in order to overcome any internal blockage and prime the pump for starting operation.

Abstract: A reversible hermetically sealed rotary compressor for use in a refrigeration system comprising a compressor cylinder, a rotor eccentrically rotatable in the cylinder and a vane dividing the cylinder between high and low pressure sides relative to direction of rotation of the rotor. Suction and discharge ports provided for each direction of rotation are automatically switched by changing the direction of rotation of the rotor.

Abstract: A stream of homogenized plastics material is divided into stream parts 10, 11 and 12 and additive introduced to the external surface of at least one stream part 10, 12 either at or before a gear pump 1. Subsequent passage through the pump 1 mixes the additive in before the stream parts 10, 11 and 12 are recombined downstream of the pump. Stream parts 10, 11 and 12 may be separated by partition on approach to the pump gear and also by partitions 8 and 9 in the pump 1 itself.

Abstract: A method for preventing a leakage loss of gases in an oil-free screw type rotary compressor including a housing, a rotor assembly comprising a pair of male and female rotor members rotatably mounted within said housing and a cooling jacket surrounding said housing, said housing and said pair of male and female rotor members defining therebetween an axially progressive series of sealed cavities for a gas, which method comprises the steps of returning as cooled a leakage gas from rotor shaft seals on the discharge side of said compressor to a first of said axially progressive series of sealed cavities, the leakage gas being returned to the compressor at a point where the suction cycle has been completed and the compression cycle has yet to begin.

Abstract: A rotary fluid pump of a non-lubrication type having a pump cavity formed within a cylindrical stator housing and a pair of recessed end head assembles. A drive shaft is eccentrically journalled in the end heads with a rotor mounted thereon with vanes slidably disposed in radial grooves in the rotor. A pair of sealing plates disposed between the ends of the stator having and the end heads divide the pump cavity into a pair of end chambers and an intermediate rotor chamber. An outlet port provides fluid communication between the rotor chamber and a discharge hole in one of the end chambers so that fluid passage for discharge to the atmosphere is provided through the rotor chamber, outlet port, end chamber and discharge hole.

Abstract: A Wankel-type engine has a housing with a chamber therein having parallel, axially spaced side surfaces joined by an end surface which has a semi-circular contour in an axially longitudinal plane. A rotor, eccentrically mounted on a shaft carried by the housing for rotation in the chamber, has a pair of side portions adjacent to the chamber side surfaces and a plurality of lobes, each having an end portion which has a semi-circular configuration corresponding to the semi-circular contour of the chamber end surface. Multi-layer, self-expanding seals engaging the chamber end surface are carried by each rotor end portion, and the rotor side portions carry seals engaging the chamber side surfaces. Lubrication is supplied to the seals. The semi-circular chamber end surface is provided on a separate member mounted between a pair of housing members, or alternatively is provided on complimentary portions of a pair of housing members.

Abstract: An injection device is proposed for internal combustion engines whose vane cell pump has two channels 23, 22. Each channel begins at the end portion of the compression recess 21 and discharges into the congruent openings 24, 25 of the support ring 17 and of the receiving ring 16, respectively. These openings are embodied as grooves and are disposed near the rotary wall 28 of the housing 10 of the injection device.

Abstract: An air vacuum pump is provided with a plurality of venting passageways in order to balance internal pressures. The present invention is found in the context of a vacuum pump or decompressor of the type having an eccentric rotor with radial lamellae mounted thereon. As the rotor turns the lamellae form intermediate chambers which produce suction and compression. According to a preferred embodiment of the invention one passageway is located to vent the chamber having the biggest volume just downstream of the suction portion of the pump. More specifically the passageway is located such that the arc along the inner surface of the chamber of the stator between the passageway and the discharge outlet is equal to or greater than the arc between the two adjoining lamellae of the rotor which occupy that portion of the chamber.

Abstract: A rotary fluid pump of the type having a housing body and a pair of recessed end heads assembled to opposite ends of the housing. A pair of resilient sealing plates may be disposed between the side of the housing and the recessed end heads to define a rotor chamber having a rotor with slidable vanes mounted thereon. Fluid inlet and outlet ports adapted to communicate with the rotor chamber are formed either in the sealing plates or in the end heads to provide pairs of inlet and outlet ports.

Abstract: Rotative machine for fluids comprising a disc or stator with spiral-like ribs limiting channels between an inlet and an outlet for fluids and, mounted for rotation in relation to the said disc, a rotor cooperating slidingly with the said disc so as to define with said channels, the conduits for the circulation of fluid, vanes of the vane wheels, with a profile conjugated with the profile of the channels and engaged in the latter, the said wheels being carried for rotation by the rotor.The channels are extended in such a manner as to allow the conduits to be operative with a vane in the portions of the channels where the vane cooperates only with one rib.Such a machine can be used in a gas turbine assembly.

Abstract: A gas ballast device for an oil sealed mechanical rotary vane vacuum pump prevents vapor condensation in the outlet port region of the low vacuum stage of the pump as a vane cyclically approaches the outlet port, whereby molecules of condensed vapor in the oil do not flow back to the inlet port of the low vacuum stage through the oil seal between the inlet and outlet ports. A flow path for atmospheric air leading to the outlet port region includes a tortuous, constricted fluid passageway. An outlet passage connecting the tortuous, constricted fluid passageway to the outlet port region is positioned so that an orifice thereof into the outlet port region is filled with and sealed by oil except during a small portion of each vane cycle immediately after the vane passes the orifice, whereby no movement of mechanical parts is employed to control air flow in response to the cyclical movement of the vanes past the orifice.

Abstract: The invention concerns an improvement in the rotary devices disclosed in U.S. Pat. Nos. 3,101,700 and 3,176,908 wherein conjointly rotated bladed and recessed rotors with interengaged blades and recesses, alternately converge and diverge with the blades and end faces on the rotors forming cells between pairs of blades and recesses which are subjected to cyclical intake and compression stages on opposite rotational positions where there are ports to supply and exhaust the cells of fluid. Blades and recesses are shaped to define unsymmetrical volumes which conform closely to one another at the downstream portions of these volumes in relation to the direction of rotation. Upstream portions of the blade and recess at an exhaust station are spaced to form a supplementary exhaust passage from the cell to the exhaust port via the recess.

Abstract: A rotary pump which comprises a cylinder having two walls which cover both ends thereof to form a compressing chamber, each of the walls includes a bearing at its center and holes around the bearing to form an inlet or an outlet of the fluid, a shaft supported by the bearings and driven by a motor, a piston having two connected arc surfaces rotatably mounted within the cylinder, each surface of the piston including a groove, an outlet port and an inlet port, a separating plate mounted in the hole of the piston and dividing the hole into two parts and separating the outlet ports and inlet ports on each part, a plunger which may be moved back and forth in the piston hole to open or close the inlet ports. The present invention can pump the fluid in periodic high pressure or stable middle pressure by controlling the movement of the plunger in piston.

Abstract: In a gas pressure increasing system for increasing the pressure of a refrigerant gas or air having a scroll compressor, a condenser, a pressure reducing means and an evaporator or a scroll compressor and a gas cooler, an exhaust gas released from the scroll compressor after having its pressure increased by the scroll compressor itself is cooled and expanded to reduce its pressure to an intermediate pressure level to produce a gas of an intermediate pressure having a cooling capability. The gas of the intermediate pressure is used to provide a force for axially sealing an orbiting scroll member of the scroll compressor as well as to cool the scroll compressor and a motor.

Abstract: In a pump having scroll vane impellers, rapid-opening additional discharge orts are formed by slats in the scroll vanes overlapping slats in the opposing end plates, thereby allowing fluids to be pumped without over-pressurization.

Abstract: A hot melt adhesive foam pump system having a first stage pump that meters molten hot melt adhesive into a second stage pump, which in turn mixes gas under pressure into the adhesive so that the gas is driven into solution with the adhesive at an adjustably controllable ratio. The pump is insensitive to changes in adhesive viscosity and pump speed, and provides uniformity of foam density and output flow rate when the adhesive is ejected from a dispenser connected to the pump.

Abstract: A gear pump for dispersing a gas into a liquid is provided with mixing means for improving the uniformity of the dispersion. In preferred form, the mixing means comprises a series of fixed, shallow, blind cavities that open to the pumping cavity between the liquid inlet and the outlet, and which are positioned to be "wiped" by the gear teeth as the gears rotate. The alternate connection and disconnection of the intertooth spaces to these cavities as the gears rotate establishes motion or turbulence of the gas/liquid mixture within the intertooth spaces, and surprisingly improves uniformity of the dispersion.