EP0294322B1 - Pump for fluid including liquified gas - Google Patents

Pump for fluid including liquified gas Download PDF

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Publication number
EP0294322B1
EP0294322B1 EP88810290A EP88810290A EP0294322B1 EP 0294322 B1 EP0294322 B1 EP 0294322B1 EP 88810290 A EP88810290 A EP 88810290A EP 88810290 A EP88810290 A EP 88810290A EP 0294322 B1 EP0294322 B1 EP 0294322B1
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EP
European Patent Office
Prior art keywords
piston
valve
end member
fluid
pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88810290A
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German (de)
French (fr)
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EP0294322A2 (en
EP0294322A3 (en
Inventor
Claudio Tschopp
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Cryopump AG
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Cryopump AG
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Publication date
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Publication of EP0294322A2 publication Critical patent/EP0294322A2/en
Publication of EP0294322A3 publication Critical patent/EP0294322A3/en
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Publication of EP0294322B1 publication Critical patent/EP0294322B1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
    • F04B39/0005—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00 adaptations of pistons
    • F04B39/0016—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00 adaptations of pistons with valve arranged in the piston
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B15/00—Pumps adapted to handle specific fluids, e.g. by selection of specific materials for pumps or pump parts
    • F04B15/06—Pumps adapted to handle specific fluids, e.g. by selection of specific materials for pumps or pump parts for liquids near their boiling point, e.g. under subnormal pressure

Definitions

  • the invention relates to a pump designed according to the preamble of claim 1 for pumping a fluid containing liquefied gas.
  • a pump also referred to as a cryogenic pump
  • the fluid to be pumped should preferably be at least largely in the liquid state.
  • the pump should, for example, be able to increase the pressure of the cryogenic fluid, which is originally at most relatively little above the ambient air pressure, typically about 0.1 to 0.5 MPa, to, for example, 20 to 50 MPa or even more.
  • single-stage, cryogenic pumps have an inlet and an outlet for the fluid to be pumped, a housing, a piston which is displaceably guided therein and a drive device which serves to displace it.
  • An end part of the housing located on the side of the piston facing away from the drive device has a first check valve, through which fluid supplied to the inlet can be sucked into the pumping chamber present between said end part and the piston.
  • a casing part of the housing enclosing the pump chamber is provided with a passage at a peripheral point, which is connected to the outlet of the pump via a second check valve connected is.
  • a cryogenic multiple pump known from WO-A-82/03337 has several single-stage pumps connected in parallel in terms of flow. Each of these has a cylindrical housing with a jacket and a multi-part head inserted into one end thereof with an end part adjoining the interior of the housing. A piston is slidably guided in the interior.
  • the fluid supply line has an angled passage running through the jacket and the end part, which opens into the pump chamber between the piston and the surface of the end part facing the piston. The mouth of this passage forms, together with a ring arranged in the interior of the housing, a first check valve which allows fluid to flow into the pump chamber when the piston moves away from the end part.
  • the fluid discharge line has an axial, stepped passage which penetrates the end part and which, together with a spring-loaded, cylindrical valve element, forms a second check valve through which fluid can be pressed out of the pump chamber when the piston approaches the end part.
  • the multiple pump known from WO-A-82/03337 has a disadvantage similar to that of the previously described single-stage pumps known on the market.
  • a pump of this type is known for example from EP-A-174 269 and has one through a partition into two cylindrical interiors divided housing, in each of which a piston is slidably guided.
  • the two pistons are fastened to a common piston rod penetrating a hole in the partition wall provided with a seal and are connected by this to a drive device.
  • the piston further away from the latter, together with a sleeve of the housing containing it and open at the end facing away from the drive device, serves as a pre-compressor in order to pump the liquefied gas through passages present in the partition into the pump chamber belonging to the high-pressure compressor.
  • the partition, the two pistons and the piston rod part connecting them must be cooled from the normal room temperature when pumping to temperatures of around - 200 ° C, depending on the type of fluid to be pumped, and because when pumping between the pre-compressor and the pumping chamber of the high-pressure compressor creates a large pressure difference, the seal required to seal the passage of the piston rod through the partition, in particular if the piston rod part penetrating the partition is relatively thin, is complex to manufacture and prone to failure. Even if the piston rod is dimensioned relatively thin, it still increases the space requirement of the pump for a given delivery rate, whereby a two-stage pump in itself requires more space than a single-stage pump with the same delivery rate.
  • this pump Because the essential part of the Partition and the casing of the housing surrounding the piston of the high-pressure compressor is located outside a container containing liquefied gas from the inlet, this pump also has the disadvantages that the high-pressure compressor is not insulated from the environment and that of the piston of the high-pressure compressor as a result of the friction generated heat can be dissipated poorly.
  • a cryogenic, likewise two-stage pump known from DE-A-2 844 719 has a housing with a cylindrical jacket. The interior of the housing is closed at one end by a bottom connected to the jacket and at the other end by a cover which is detachably fastened.
  • a first piston which is arranged displaceably in the interior, is connected to a piston rod penetrating the cover and can be displaced by it. The first piston is provided on its side facing away from the piston rod with a sleeve coaxial to the jacket.
  • a second piston which is displaceable with respect to this but is fixed with respect to the housing, is arranged in this and is fixed rigidly to the floor with a tube piece.
  • the area of the interior space between the cover and the first piston is referred to in the cited publication as a suction chamber and forms a first pump chamber belonging to the first pump stage.
  • the space between the two pistons inside the sleeve is referred to in the publication as a compression chamber and forms a second pumping chamber belonging to the second pumping stage.
  • a fluid supply line opens into the suction chamber via a first check valve with a passage penetrating the jacket in the radial direction. This is connected to the compression chamber via a check valve, which has passages penetrating the first piston and a spring-loaded ring.
  • the the latter is connected to a fluid discharge line via a check valve arranged in the second piston through said pipe section and through the base.
  • the suction chamber is still connected to an overflow line by a passage penetrating the jacket and an overflow valve.
  • the area of the interior space between the bottom and the first piston, surrounding the sleeve and the pipe back, is also connected to the overflow line through the opening in the jacket.
  • the invention is therefore based on the object of avoiding and in particular enabling disadvantages of the known pumps, for example starting from the single-stage pump known from WO-A-82/03337, to keep the evaporation of liquid fluid in the pumping chamber as low as possible, without having to precede a pump stage with this pump chamber.
  • the pump shown in FIG. 1 has a base 1 which carries a drive device 3 and a sleeve-shaped connecting piece 5 provided with ribs.
  • An elongated housing, designated as a whole by 11, is detachably fastened to the latter, which has an elongated support 13 designed as a continuously open sleeve, one end section of which is screwed to the connecting piece 5 and the other end section having a radially outwardly projecting collar 13a is provided.
  • a bushing 15 which can be seen particularly clearly in FIG.
  • the continuously open bushing 15 has a cylindrical inner surface 15c which extends over most of its length and an extension 15d in its end section facing away from the drive device 3, to which a further extension 15e adjoins.
  • the end of the bushing 15 facing away from the drive device 3 is closed off by an end wall consisting of a separate end part 17, or in short, wall of the housing 11, which has a projection protruding into the extension 15e and is sealed with an annular seal 19.
  • a clamping ring 21 is provided by threaded bolts and nuts Fastening elements 23 releasably connected to the collar 13a and presses the end part 17 serving as the end wall against the collar 15b and this against the collar 13a, as a result of which the end part 17 is detachably connected to the bush 15 and this is detachably connected to the sleeve-shaped carrier 13.
  • the housing 11 contains an elongated inner space designated as a whole by 31, in the cylindrical part of which is limited by the bushing 15, a piston 35 is displaceably guided and sealed with annular seals 37.
  • the piston 35 is connected to a crank of the drive device 3 by means of a piston rod 39, which consists at least in part of it with a one-piece body, a portion of the carrier 13 being designed as a passage 13b and two ring-shaped seals 41 and a sleeve-shaped seal 43 for sealing the piston rod contains.
  • the carrier 13, the bushing 15, the end part 17, the interior 31, the piston 35 and the piston rod 39 have a common, horizontal axis 45 or, more precisely, the longitudinal central axis 45 and are at least generally rotationally symmetrical to this.
  • the area of the interior 31 located between the end part 17 and the piston is referred to below as the pump chamber 33.
  • the largest part of the housing 11 and in particular at least its part that contacts and seals the piston 35, ie the bush 15, and the housing end part 17 are located in the interior 53 of a container 51, which is sealed off from the environment.
  • the container 51 has a heat-insulating wall an inner wall and an outer wall separated therefrom by a preferably evacuated intermediate space. Otherwise, the wall of the container 51 consists of two parts, one of which, the first near the Connection piece 5 is tightly attached to the sleeve-shaped carrier 13 and the other, second detachable by releasable connecting means and tightly attached to the first part.
  • the lowermost portions of the housing 11 are located slightly above the lowest point of the container interior 53 and the axis 45 of the housing 11 and piston 35 is in the lower half of the container interior 53 and thus below the horizontal longitudinal central axis 55 of the generally cylindrical Container 51.
  • a nozzle serving as an inlet 57 for the fluid to be pumped opens, for example in the lowest region of the container 51, into the interior 53 thereof.
  • the end part 17 has at least one passage 59, namely at least two and preferably even more passages 59 distributed around the axis 45 Together with the container interior 53, these form fluid supply means 53, 59 which connect the inlet 57 to the pump chamber 33.
  • a plate-shaped valve element 61 has a central through-opening 61a which is coaxial with the axis 45 and is guided in the pump chamber 33 so as to be displaceable along the axis 45 and thus in the direction of displacement of the piston 35, the possible displacement path of the valve element 61 on one side through the end part 17 of the housing and on the other side is limited by the end of the extension 15d facing the drive device 3.
  • the passages 59 together with the valve element 61 serve as the first check valve 63, the valve seat of which is formed by the flat end face of the end part 17 facing the piston 35.
  • the end part 17 of the housing 11 is further provided with a central passage 65 which is coaxial with the axis 45 and which has a section which widens away from the pump chamber 33 and forms a valve seat.
  • a spherical valve element 67 is movably held, which is pressed against the valve seat by a spring 69.
  • the passage 65 serves together with the valve element 67 and the spring 69 as a second check valve 71.
  • a line 75 fastened to the end part 17 and tightly connected to the passage 65 and consisting, for example, of a tube leads through the container interior 53 to a wall of the container 51 penetrating bushing and forms there together with this an outlet 77 for the pumped fluid.
  • the passage 65 forms, together with the line 75, fluid discharge means 65, 75 which connect the pump chamber 33 to the outlet 77.
  • the diameter of the section of the piston rod 39 adjoining the piston 35 is smaller than the diameter of the piston and of the inner surface 15c of the bush.
  • the sleeve-shaped carrier 13 is provided between the bushing 15 and the bushing 13b with at least one hole 79 penetrating its jacket, namely with at least two holes 79 distributed over its circumference. These open into a free area of the interior 31 of the housing 11 that surrounds the piston rod 39.
  • the piston 35 has a blind hole 81 drilled into it from its end facing the pump chamber 33. This has a hole in the direction of the end part 17 of the housing 11 conically widening mouth section, which serves as valve seat 83.
  • the piston on its side facing the drive device 3 and facing away from the pumping chamber 33 between its cylindrical outer surface and the piston rod 39 is delimited by a conical annular surface, from which inclined holes 85 are drilled in the piston, which open into the base section of the blind hole 81.
  • a guide body 87 is inserted between the base section and the valve seat 83, which has a bushing and / or has hub-like middle section. From this, rib-like or wing-like projections distributed around it protrude outward, the free edges of which are pressed into the blind hole 81 and hold the guide body therein, additional securing means and / or fastening means possibly being present to secure the guide body 87 and rigidly fixed in the piston.
  • Channels 89 are distributed between the mutually adjacent, rib-like or wing-like projections of the guide body around its hub-like central section.
  • the number of channels 89 is, for example, equal to the number of holes 85 and can be, for example, approximately four to eight, depending on the size and intended delivery capacity of the pump.
  • a valve element 91 has a plate which is coaxial with the axis 45 and has a conical section which fits into the conical valve seat 83 and on its side facing the end part 17 has a short, cylindrical projection, the diameter of which is somewhat smaller than the diameter of the through opening 61a of the valve element 61 first check valve.
  • the valve element 91 is rigidly connected to a bolt 93 and, for example, is formed together with this from a one-piece body.
  • the bolt 93 penetrates the guide hole 87a of the guide body 87, is displaceably guided therein parallel to the direction of displacement of the piston and is provided with a thread on its end facing away from the valve element 91, onto which a nut 95 is screwed.
  • there is at least one spring 97 namely a helical spring surrounding the bolt 93, which exerts a force on the nut 95 and on the bolt 93 a force directed away from the end part 17 towards the drive device 3 on the valve element 91 .
  • the free areas of the blind hole 81 form a passage together with the holes 85 and the channels 89.
  • the housing 11 consists at least essentially of metallic, preferably made of stainless steel parts, the bushing 15 being made, for example, of hardened stainless steel.
  • the piston 35 consists, for example, of a beryllium-copper alloy.
  • the valve element 61 is made of, for example, stainless steel, the valve element 67 is made of metallic material, such as stainless steel, and / or polytetrafluoroethylene, and the valve element 91 is made of a metallic material, such as a beryllium-copper alloy or the copper known under the name Monel. Nickel alloy.
  • the input 57 is connected, for example, to a reservoir which contains the fluid to be pumped, ie liquefied gas.
  • the pressure present in the reservoir is at least equal to the ambient air pressure and preferably somewhat greater than this, so that the fluid is pressed into the reservoir 57 to the inlet 57 and into the interior 53 of its container 51 by the pressure present in the reservoir.
  • the container 51 is also provided with a gas outlet 101, the inner end of which is in the vicinity of the uppermost region of the container interior 53.
  • the gas outlet 101 is connected, for example, to the aforementioned reservoir via a gas return line or to the surroundings via a pressure relief valve.
  • the outlet 77 for the liquefied and compressed by the pump gas can, for example, with an evaporation and filling device be connected to fill the now gaseous but highly compressed fluid in a pressure vessel.
  • fluid consisting at least mainly of liquefied gas flows into the interior 53 of the container 51 through the inlet 57.
  • the liquefied gas rises in the container, for example, to level 111, above which level evaporation then returns to the gaseous state.
  • the parts of the housing 11 located within the container interior 53, and in particular its bush 15 and end part 17, which together form the actual pump cylinder, are of low pressure, i.e. surrounded by the feed, not yet pumped, liquefied gas.
  • the drive device 3 When pumping, the drive device 3 alternately pushes the piston 35 back and forth along the horizontal axis 45. If the piston moves to the left in FIGS. 1 and 2, ie away from the end part 17 in the time interval referred to below as the suction stroke, as was assumed when drawing the valve elements, it sucks fluid out of the container interior 53 in the manner indicated by arrows through the first check valve 63 as well as through the holes 79 and the passage of the third Check valve 99 into the pump chamber 33. If the piston then moves in the opposite direction in the time interval referred to below as the compression stroke, it pushes fluid out of the pump chamber 33 via the second check valve 71 to the outlet 77.
  • both the first and third check valves When both the first and third check valves are open, they together make one proportionate large passage cross-section, which also counteracts the development of pressure drops and the vaporization of liquefied gas.
  • the valve element 91 can, for example, be designed such that the annular surface of its conical section facing the end part 17, when it rests on the valve seat 83 in its closed position, is approximately flush with the end face of the piston. Furthermore, the displacement path of the piston can be determined such that it and the said annular surface of the valve element 91 at the end of the compression stroke, when the valve element 61 abuts the end part 17, in turn lie at least approximately on the valve element 61 and that the projection of the valve element 91 into the central one Opening 61a of valve element 61 projects into it. If these conditions are met, the free volume of the pumping chamber is reduced to almost zero at the end of the compression stroke, so that there is practically no dead space in the pumping chamber 33 and between it and the valve seats of the three check valves.
  • the pump can of course be modified in various ways.
  • the inlet 57 can open parallel to the piston axis through the end wall of the container 51 located on the right in FIG. 1 and into its interior 53.
  • a filter screen can also be arranged, which can be conical, for example, to achieve a large surface area.
  • the passages of the three check valves and their remaining training can be changed in a variety of ways.
  • the end part 17 serving as the end wall of the housing 11 can be replaced, for example, by a thicker end part, measured in the axial direction, the outer surface of which is provided with an annular groove which widens outwards from the bottom thereof.
  • the passages corresponding to the passages 59 can then, at their ends facing away from the pump chamber 33, open into the end face of the end part 17 facing away from the bushing 15 into the annular groove provided in the lateral surface thereof, as in FIG.
  • At least one spring can be provided which acts on the movable valve element of the first check valve with a force directed away from the piston 35 towards the housing end part 17.
  • the valve element of the first check valve can be provided, for example, on its side facing away from the piston with at least one finger protruding into a hole in the housing end part, onto the end of which a nut is screwed away from the piston.
  • a helical spring can then be held on the finger, which engages on one end on a radial surface of the housing end part and on the other end on said nut.
  • the finger-receiving and guiding hole of the housing end part can be arranged, for example, coaxially to the piston in the housing end part and therefore at the point at which the passage 65 of the second check valve is located in FIG.
  • the passage of the second check valve could then, for example open in the radial direction through the jacket of the bushing 15 into the pump chamber 33.
  • the movable valve element 67 of the second check valve 71 can consist of a differently shaped body, for example a sleeve, instead of a ball, which is closed at the valve seat end by an end wall and in the other, open end of a spring corresponding to the spring 69 attacks.
  • the guide body 87 used to guide the bolt 93 of the third check valve can be formed from a bushing which has a cylindrical outer surface that is connected around its axis.
  • the bushing can be pressed into the blind hole 81 in a manner analogous to that described for the guide body 87 and additionally fixed in the piston with securing and / or fastening means.
  • the latter can have, for example, at least one grub screw and, for example, several such, which are screwed in under one of the seals of the piston distributed over its circumference in radial threaded bores of the piston jacket and engage with their, for example, conical ends facing the piston axis in holes in the bushing forming the guide body .
  • the channels 89 shown in FIG. 2 can then be formed by holes, preferably bores, distributed around the axis and the hole of the bush corresponding to the guide hole 87a.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Details Of Reciprocating Pumps (AREA)
  • Compressor (AREA)

Description

Die Erfindung betrifft eine gemäss dem Oberbegriff des Anspruches l ausgebildete Pumpe zum Pumpen eines verflüssigtes Gas aufweisenden Fluids. Eine solche, auch als cryogene Pumpe bezeichnete Pumpe kann beispielsweise verwendet werden, um ein Fluid zu pumpen, das mindestens ein verflüssigtes Gas, wie flüsssigen Stickstoff, Sauerstoff oder Wasserstoff oder flüssiges Argon oder flüssige Luft und eventuell auch noch ein wenig gasförmiges Fluid enthält. Das zu pumpende Fluid soll sich jedoch vorzugsweise zumindest zum grössten Teil im flüssigen Aggregatszustand befinden. Die Pumpe soll den beispielsweise ursprünglich höchstens relativ wenig über dem Umgebungs-Luftdruck liegenden, typischerweise etwa 0,1 bis 0,5 MPa betragenden Druck des cryogenen Fluids auf beispielsweise 20 bis 50 MPa oder noch mehr erhöhen können.The invention relates to a pump designed according to the preamble of claim 1 for pumping a fluid containing liquefied gas. Such a pump, also referred to as a cryogenic pump, can be used, for example, to pump a fluid that contains at least one liquefied gas, such as liquid nitrogen, oxygen or hydrogen or liquid argon or liquid air, and possibly also a little gaseous fluid. However, the fluid to be pumped should preferably be at least largely in the liquid state. The pump should, for example, be able to increase the pressure of the cryogenic fluid, which is originally at most relatively little above the ambient air pressure, typically about 0.1 to 0.5 MPa, to, for example, 20 to 50 MPa or even more.

Auf dem Markt bekannte, einstufige, cryogene Pumpen besitzen einen Ein- sowie einen Ausgang für das zu pumpende Fluid, ein Gehäuse, einen verschiebbar in diesem geführten Kolben und eine zum Verschieben von diesem dienende Antriebsvorrichtung. Ein sich auf der der Antriebsvorrichtung abgewandten Seite des Kolbens befindender Endteil des Gehäuses weist ein erstes Rückschlagventil auf, durch welches dem Eingang zugeführtes Fluid in die zwischen dem genannten Endteil und dem Kolben vorhandene Pumpkammer hinein gesaugt werden kann. Ein die Pumpkammer umschliessender Mantelteil des Gehäuses ist bei einer Umfangsstelle mit einem Durchgang versehen, der über ein zweites Rückschlagventil mit dem Ausgang der Pumpe verbunden ist. Wenn sich der Kolben beim Betrieb vom genannten Endteil wegbewegt und Fluid in die Pumpkammer hineinpumpt, kann insbesondere in der Anfangsphase eines solchen Saugtaktes wegen des entstehenden Unterdrucks ein verhältnismässig grosser Teil des verflüssigten Gases wieder in den gasförmigen Aggregatszustand gelangen, was den Betrieb der Pumpe stört und einen erheblichen Nachteil darstellt.Known on the market, single-stage, cryogenic pumps have an inlet and an outlet for the fluid to be pumped, a housing, a piston which is displaceably guided therein and a drive device which serves to displace it. An end part of the housing located on the side of the piston facing away from the drive device has a first check valve, through which fluid supplied to the inlet can be sucked into the pumping chamber present between said end part and the piston. A casing part of the housing enclosing the pump chamber is provided with a passage at a peripheral point, which is connected to the outlet of the pump via a second check valve connected is. If, during operation, the piston moves away from the end part mentioned and pumps fluid into the pumping chamber, this can occur in particular in the initial phase Due to the resulting negative pressure, a relatively large part of the liquefied gas return to the gaseous state of aggregation, which disrupts the operation of the pump and represents a considerable disadvantage.

Eine aus der WO-A-82/03337 bekannte, cryogene Mehrfach-Pumpe besitzt mehrere strömungsmässig parallel geschaltete, einstufige Pumpen. Jede von diesen besitzt ein zylindrisches Gehäuse mit einem Mantel und einem in dessen eines Ende eingesetzten, mehrteiligen Kopf mit einem an den Innenraum des Gehäuses angrenzenden Endteil. Im Innenraum ist ein Kolben verschiebbar geführt. Die Fluid-Zuleitung weist einen abgewinkelt durch den Mantel und den Endteil hindurch verlaufenden Durchgang auf, der bei der dem Kolben zugewandten Fläche des Endteils in die zwischen diesem und dem Kolben vorhandene Pumpkammer mündet. Die Mündung dieses Durchgangs bildet zusammen mit einem im Gehäuse-Innenraum angeordneten Ring ein erstes Rückschlagventil, das bei sich vom Endteil wegbewegenden Kolben das Einströmen von Fluid in die Pumpkammer ermöglicht. Die Fluid-Ableitung weist einen axialen, den Endteil durchdringenden, abgestuften Durchgang auf, der zusammen mit einem federbelasteten, zylindrischen Ventilelement ein zweites Rückschlagventil bildet, durch das bei sich dem Endteil näherndem Kolben Fluid aus der Pumpkammer herausgepresst werden kann. Die aus der WO-A-82/03337 bekannte Mehrfach-Pumpe hat einen ähnlichen Nachteil wie die vorher beschriebenen, auf dem Markt bekannten, einstufigen Pumpen.A cryogenic multiple pump known from WO-A-82/03337 has several single-stage pumps connected in parallel in terms of flow. Each of these has a cylindrical housing with a jacket and a multi-part head inserted into one end thereof with an end part adjoining the interior of the housing. A piston is slidably guided in the interior. The fluid supply line has an angled passage running through the jacket and the end part, which opens into the pump chamber between the piston and the surface of the end part facing the piston. The mouth of this passage forms, together with a ring arranged in the interior of the housing, a first check valve which allows fluid to flow into the pump chamber when the piston moves away from the end part. The fluid discharge line has an axial, stepped passage which penetrates the end part and which, together with a spring-loaded, cylindrical valve element, forms a second check valve through which fluid can be pressed out of the pump chamber when the piston approaches the end part. The multiple pump known from WO-A-82/03337 has a disadvantage similar to that of the previously described single-stage pumps known on the market.

Zur Behebung dieses Nachteils ist es bekannt, der Pumpkammer einen Vorverdichter vorzuschalten und die Pumpe also zweistufig auszubilden. Eine Pumpe dieser Art ist zum Beispiel aus der EP-A-174 269 bekannt und besitzt ein durch eine Trennwand in zwei zylindrische Innenräume unterteiltes Gehäuse, in denen je ein Kolben verschiebbar geführt ist. Die beiden Kolben sind an einer gemeinsamen, ein mit einer Dichtung versehenes Loch der Trennwand durchdringenden Kolbenstange befestigt und durch diese mit einer Antriebsvorrichtung verbunden. Der weiter von der letzteren entfernte Kolben dient zusammen mit einer ihn enthaltenden, am der Antriebsvorrichtung abgewandten Ende offenen Hülse des Gehäuses als Vorverdichter, um das verflüssigte Gas durch in der Trennwand vorhandene Durchgänge hindurch, in die zum Hochdruckverdichter gehörende Pumpkammer zu pumpen. Damit der die beiden Kolben verbindende Teil der Kolbenstange der aus der EP-A-174 269 bekannten Pumpe in den zwischen der Trennwand und den beiden Kolben vorhandenen, zum Aufnehmen des zu pumpenden Fluids dienenden Kammern nicht zuviel Platz beansprucht, sollte er wesentlich dünner sein als die Kolben. Wenn die Kolbenstange jedoch dünn bemessen wird, besteht beim Betrieb eine erhebliche Gefahr, dass sie bricht. Da die Trennwand, die beiden Kolben und der diese verbindende Kolbenstangenteil ausgehend von der normalen Raumtemperatur beim Pumpen auf abhängig von der Art des zu pumpenden Fluids etwa in der Grösse von - 200°C liegende Temperaturen abgekühlt werden müssen und da beim Pumpen zwischen dem Vorverdichter und der Pumpkammer des Hochdruckverdichters ein grosser Druckunterschied entsteht, ist die zum Dichten der Durchführung der Kolbenstange durch die Trennwand erforderliche Dichtung, insbesondere wenn der die Trennwand durchdringende Kolbenstangenteil verhältnismässig dünn ist, aufwendig in der Herstellung und beim Betrieb störanfällig. Auch wenn die Kolbenstange verhältnismässig dünn bemessen wird, vergrössert sie dennoch, bei vorgegebener Förderleistung, den Platzbedarf der Pumpe, wobei eine zweistufige Pumpe im übrigen schon an sich mehr Platz als eine einstufige Pumpe mit gleicher Förderleistung benötigt. Weil der wesentliche Teil der Trennwand und der den Kolben des Hochdruckverdichters umschliessende Mantel des Gehäuses sich ausserhalb eines vom Eingang zugeführtes, verflüssigtes Gas enthaltenden Behälters befindet, hat diese Pumpe zudem die Nachteile, dass der Hochdruckverdichter gegen die Umgebung nicht isoliert ist und dass die vom Kolben des Hochdruckverdichters infolge der Reibung erzeugte Wärme schlecht abgeführt werden kann.To remedy this disadvantage, it is known to precede the pumping chamber with a precompressor and thus to design the pump in two stages. A pump of this type is known for example from EP-A-174 269 and has one through a partition into two cylindrical interiors divided housing, in each of which a piston is slidably guided. The two pistons are fastened to a common piston rod penetrating a hole in the partition wall provided with a seal and are connected by this to a drive device. The piston further away from the latter, together with a sleeve of the housing containing it and open at the end facing away from the drive device, serves as a pre-compressor in order to pump the liquefied gas through passages present in the partition into the pump chamber belonging to the high-pressure compressor. So that the part of the piston rod connecting the two pistons of the pump known from EP-A-174 269 does not take up too much space in the chambers between the partition and the two pistons, which serve to hold the fluid to be pumped, it should be considerably thinner than the pistons. However, if the piston rod is dimensioned thin, there is a considerable risk that it will break during operation. Since the partition, the two pistons and the piston rod part connecting them must be cooled from the normal room temperature when pumping to temperatures of around - 200 ° C, depending on the type of fluid to be pumped, and because when pumping between the pre-compressor and the pumping chamber of the high-pressure compressor creates a large pressure difference, the seal required to seal the passage of the piston rod through the partition, in particular if the piston rod part penetrating the partition is relatively thin, is complex to manufacture and prone to failure. Even if the piston rod is dimensioned relatively thin, it still increases the space requirement of the pump for a given delivery rate, whereby a two-stage pump in itself requires more space than a single-stage pump with the same delivery rate. Because the essential part of the Partition and the casing of the housing surrounding the piston of the high-pressure compressor is located outside a container containing liquefied gas from the inlet, this pump also has the disadvantages that the high-pressure compressor is not insulated from the environment and that of the piston of the high-pressure compressor as a result of the friction generated heat can be dissipated poorly.

Eine cryogene, ebenfalls zweistufige, aus der DE-A-2 844 719 bekannte Pumpe besitzt ein Gehäuse mit einem zylindrischen Mantel. Der Innenraum des Gehäuses ist am einen Ende durch einen mit dem Mantel zusammenhängenden Boden und am anderen Ende durch einen lösbar befestigten Deckel abgeschlossen. Ein erster, verschiebbar im Innenraum angeordneter Kolben ist mit einer den Deckel durchdringenden Kolbenstange verbunden und kann durch diese verschoben werden. Der erste Kolben ist auf seiner der Kolbenstange abgewandten Seite mit einer zum Mantel koaxialen Hülse versehen. In dieser ist ein bezüglicher dieser verschiebbarer, aber bezüglich des Gehäuses feststehender, zweiter Kolben angeordnet, der mit einem Rohrstück starr am Boden befestigt ist. Der zwischen dem Deckel und dem ersten Kolben vorhandene Bereich des Innenraums ist in der zitierten Publikation als Ansaugkammer bezeichnet und bildet eine zur ersten Pumpstufe gehörende, erste Pumpkammer. Der zwischen den beiden Kolben im Innern der Hülse vorhandene Raumbereich ist in der Publikation als Kompressionskammer bezeichnet und bildet eine zur zweiten Pumpstufe gehörende, zweite Pumpkammer. Eine Fluid-Zuleitung mündet über ein erstes Rückschlagventil mit einem den Mantel in radialer Richtung durchdringenden Durchgang in die Ansaugkammer. Diese ist über ein Rückschlagventil, das den ersten Kolben durchdringende Durchgänge und einen federbelasteten Ring aufweist, mit der Kompressionskammer verbunden. Die letztere ist über ein im zweiten Kolben angeordnetes Rückschlagventil durch das genannte Rohrstück und den Boden hindurch mit einer Fluid-Ableitung verbunden. Die Ansaugkammer ist noch durch einen den Mantel durchdringenden Durchgang und ein Überlauf-Ventil mit einer Überlaufleitung verbunden. Der zwischen dem Boden und dem ersten Kolben vorhandene, die Hülse und das Rohrsück umgebende Bereich des Innenraums ist durch die im Mantel vorhandene Öffnung hindurch ebenfalls mit der Überlaufleitung verbunden. Wenn der erste Kolben vom Deckel zum Boden hin verschoben wird, saugt er Fluid über das zur Zuleitung gehörende Rückschlagventil in die Ansaugkammer hinein und presst gleichzeitig Fluid aus der Kompressionskammer heraus und durch das mit der Ableitung verbundene Rückschlagventil hindurch. Beim Ansaugen von Fluid in die Ansaugkammer verdampft ein Teil dieses Fluids. Wenn der erste Kolben danach in Richtung vom Boden zum Deckel hin verschoben wird, kann Fluid von der Ansaugkammer über das im ersten Kolben vorhandene Rückschlagventil in die Kompressionskammer fliessen. Ferner soll der erste Kolben gleichzeitig das vorher beim Ansaugen verdampfte Fluid über das Überlauf-Ventil aus der Ansaugkammer herausdrücken.A cryogenic, likewise two-stage pump known from DE-A-2 844 719 has a housing with a cylindrical jacket. The interior of the housing is closed at one end by a bottom connected to the jacket and at the other end by a cover which is detachably fastened. A first piston, which is arranged displaceably in the interior, is connected to a piston rod penetrating the cover and can be displaced by it. The first piston is provided on its side facing away from the piston rod with a sleeve coaxial to the jacket. A second piston, which is displaceable with respect to this but is fixed with respect to the housing, is arranged in this and is fixed rigidly to the floor with a tube piece. The area of the interior space between the cover and the first piston is referred to in the cited publication as a suction chamber and forms a first pump chamber belonging to the first pump stage. The space between the two pistons inside the sleeve is referred to in the publication as a compression chamber and forms a second pumping chamber belonging to the second pumping stage. A fluid supply line opens into the suction chamber via a first check valve with a passage penetrating the jacket in the radial direction. This is connected to the compression chamber via a check valve, which has passages penetrating the first piston and a spring-loaded ring. The the latter is connected to a fluid discharge line via a check valve arranged in the second piston through said pipe section and through the base. The suction chamber is still connected to an overflow line by a passage penetrating the jacket and an overflow valve. The area of the interior space between the bottom and the first piston, surrounding the sleeve and the pipe back, is also connected to the overflow line through the opening in the jacket. When the first piston is displaced from the cover towards the bottom, it sucks fluid into the suction chamber via the check valve belonging to the supply line and at the same time presses fluid out of the compression chamber and through the check valve connected to the discharge line. When fluid is drawn into the suction chamber, some of this fluid evaporates. If the first piston is then displaced in the direction from the bottom to the cover, fluid can flow into the compression chamber from the suction chamber via the check valve present in the first piston. Furthermore, the first piston should at the same time push the fluid that had previously evaporated during suction via the overflow valve out of the suction chamber.

Der Erfindung liegt daher die Aufgabe zugrunde, Nachteile der bekannten Pumpen zu vermeiden und insbesondere zu ermöglichen, beispielsweise ausgehend von der aus der WO-A-82/03337 bekannten, einstufigen Pumpe, die Verdampfung von flüssigem Fluid in der Pumpkammer möglichst gering zu halten, ohne dieser Pumpkammer eine Vorverdichterstufe vorschalten zu müssen.The invention is therefore based on the object of avoiding and in particular enabling disadvantages of the known pumps, for example starting from the single-stage pump known from WO-A-82/03337, to keep the evaporation of liquid fluid in the pumping chamber as low as possible, without having to precede a pump stage with this pump chamber.

Diese Aufgabe wird durch eine Pumpe der im Oberbegriff des Anspruches 1 angegebenen Gattung gelöst, wobei die Pumpe erfindungsgemäss durch den kennzeichnenden Teil des Anspruches 1 gekennzeichnet ist. Vorteilhafte Ausgestaltungen der Pumpe gehen aus den abhängigen Ansprüchen hervor.This object is achieved by a pump of the type specified in the preamble of claim 1, the pump according to the invention being characterized by the characterizing part of claim 1. Advantageous refinements of the pump emerge from the dependent claims.

Der Erfindungsgegenstand wird nun anhand eines in der Zeichnung dargestellten Ausführungsbeispiels einer Pumpe erläutert. In der Zeichnung zeigt

die Figur 1
eine teils in Seitenansicht und teils im Vertikalschnitt dargestellte Pumpe und
die Figur 2
einen Schnitt durch Teile der in Figur 1 ersichtlichen Pumpe, in grösserem Massstab.
The object of the invention will now be explained with reference to an embodiment of a pump shown in the drawing. In the drawing shows
the figure 1
a pump shown partly in side view and partly in vertical section
the figure 2
a section through parts of the pump shown in Figure 1, on a larger scale.

Die in der Figur 1 ersichtliche Pumpe weist einen Sockel 1 auf, der eine Antriebsvorrichtung 3 und ein hülsenförmiges, mit Rippen versehenes Verbindungsstück 5 trägt. An diesen ist ein als Ganzes mit 11 bezeichnetes längliches Gehäuse lösbar befestigt, das einen länglichen, als durchgehend offene Hülse ausgebildeten Träger 13 aufweist, dessen einer Endabschnitt mit dem Verbindungsstück 5 verschraubt ist und dessen anderer Endabschnitt mit einem radial nach aussen ragenden, ringflanschartigen Kragen 13a versehen ist. Eine besonders deutlich in der Figur 2 ersichtliche Buchse 15 hat einen hohlzylindrischen Mantel 15a, der im letztgenannten Endabschnitt des hülsenförmigen Trägers 13 steckt, und einen radial nach aussen ragenden Kragen 15b der an der radialen Endfläche des Kragens 13a anliegt. Die durchgehend offene Buchse 15 hat eine sich über den grössten Teil ihrer Länge erstreckende, zylindrische Innenfläche 15c und in ihrem der Antriebsvorrichtung 3 abgewandten Endabschnitt eine Erweiterung 15d, an die eine noch weitere Erweiterung 15e anschliesst. Das der Antriebsvorrichtung 3 abgewandte Ende der Buchse 15 ist durch eine aus einem separaten Endteil 17 bestehende Stirnwand, oder kurz gesagt, Wand des Gehäuses 11 abgeschlossen, die einen in die Erweiterung 15e hineinragenden Vorsprung aufweist und mit einer ringförmigen Dichtung 19 abgedichtet ist. Ein Klemmring 21 ist durch Gewindebolzen und Muttern aufweisende Befestigungselemente 23 lösbar mit dem Kragen 13a verbunden und drückt den als Stirnwand dienenden Endteil 17 an den Kragen 15b und diesen an den Kragen 13a an, wodurch der Endteil 17 lösbar mit der Buchse 15 und diese lösbar mit dem hülsenförmigen Träger 13 verbunden wird.The pump shown in FIG. 1 has a base 1 which carries a drive device 3 and a sleeve-shaped connecting piece 5 provided with ribs. An elongated housing, designated as a whole by 11, is detachably fastened to the latter, which has an elongated support 13 designed as a continuously open sleeve, one end section of which is screwed to the connecting piece 5 and the other end section having a radially outwardly projecting collar 13a is provided. A bushing 15, which can be seen particularly clearly in FIG. 2, has a hollow cylindrical jacket 15a, which is inserted in the latter end section of the sleeve-shaped carrier 13, and a radially outwardly projecting collar 15b, which bears against the radial end surface of the collar 13a. The continuously open bushing 15 has a cylindrical inner surface 15c which extends over most of its length and an extension 15d in its end section facing away from the drive device 3, to which a further extension 15e adjoins. The end of the bushing 15 facing away from the drive device 3 is closed off by an end wall consisting of a separate end part 17, or in short, wall of the housing 11, which has a projection protruding into the extension 15e and is sealed with an annular seal 19. A clamping ring 21 is provided by threaded bolts and nuts Fastening elements 23 releasably connected to the collar 13a and presses the end part 17 serving as the end wall against the collar 15b and this against the collar 13a, as a result of which the end part 17 is detachably connected to the bush 15 and this is detachably connected to the sleeve-shaped carrier 13.

Das Gehäuse 11 enthält einen als Ganzes mit 31 bezeichneten, länglichen Innenraum, in dessen von der Buchse 15 begrenztem, zylindrischem Teil ein Kolben 35 verschiebbar geführt und mit ringförmigen Dichtungen 37 abgedichtet ist. Der Kolben 35 ist durch eine mindestens zum Teil mit ihm zusammen aus einem einstückigen Körper bestehende Kolbenstange 39 mit einer Kurbel der Antriebsvorrichtung 3 verbunden, wobei ein Abschnitt des Trägers 13 als Durchführung 13b ausgebildet ist und zwei ringförmige Dichtungen 41 sowie eine manschettenförmige Dichtung 43 zum Abdichten der Kolbenstange enthält. Der Träger 13, die Buchse 15, der Endteil 17, der Innenraum 31, der Kolben 35 und die Kolbenstange 39 haben eine gemeinsame, horizontale Achse 45 oder, genauer gesagt, Längsmittelachse 45 und sind zumindest im allgemeinen zu dieser rotationssymmetrisch. Der sich zwischen dem Endteil 17 und dem Kolben befindende Bereich des Innenraums 31 wird im folgenden als Pumpkammer 33 bezeichnet.The housing 11 contains an elongated inner space designated as a whole by 31, in the cylindrical part of which is limited by the bushing 15, a piston 35 is displaceably guided and sealed with annular seals 37. The piston 35 is connected to a crank of the drive device 3 by means of a piston rod 39, which consists at least in part of it with a one-piece body, a portion of the carrier 13 being designed as a passage 13b and two ring-shaped seals 41 and a sleeve-shaped seal 43 for sealing the piston rod contains. The carrier 13, the bushing 15, the end part 17, the interior 31, the piston 35 and the piston rod 39 have a common, horizontal axis 45 or, more precisely, the longitudinal central axis 45 and are at least generally rotationally symmetrical to this. The area of the interior 31 located between the end part 17 and the piston is referred to below as the pump chamber 33.

Der grösste Teil des Gehäuses 11 und insbesondere mindestens dessen den Kolben 35 berührender sowie dicht führender Teil, d.h. die Buchse 15, und der GehäuseEndteil 17 befinden sich im gegen die Umgebung dicht abgeschlossenen Innenraum 53 eines Behälters 51. Der Behälter 51 besitzt eine wärmeisolierende Wandung mit einer Innenwand und einer von dieser durch einen vorzugsweise evakuierten Zwischen raum getrennten Aussenwand. Im übrigen besteht die Wandung des Behälters 51 aus zwei Teilen, von denen der eine, erste in der Nähe des Verbindungsstückes 5 dicht am hülsenförmigen Träger 13 befestigt und der andere, zweite durch lösbare Verbindungsmittel lösbar sowie dicht am ersten Teil befestigt ist. Die untersten Abschnitte des Gehäuses 11 befinden sich geringfügig über der tiefsten Stelle des Behälter-Innenraums 53 und die Achse 45 des Gehäuses 11 und Kolbens 35 befindet sich in der unteren Hälfte des Behälter-Innenraums 53 und also unterhalb der horizontalen Längsmittelachse 55 des im allgemeinen zylindrischen Behälters 51.The largest part of the housing 11 and in particular at least its part that contacts and seals the piston 35, ie the bush 15, and the housing end part 17 are located in the interior 53 of a container 51, which is sealed off from the environment. The container 51 has a heat-insulating wall an inner wall and an outer wall separated therefrom by a preferably evacuated intermediate space. Otherwise, the wall of the container 51 consists of two parts, one of which, the first near the Connection piece 5 is tightly attached to the sleeve-shaped carrier 13 and the other, second detachable by releasable connecting means and tightly attached to the first part. The lowermost portions of the housing 11 are located slightly above the lowest point of the container interior 53 and the axis 45 of the housing 11 and piston 35 is in the lower half of the container interior 53 and thus below the horizontal longitudinal central axis 55 of the generally cylindrical Container 51.

Ein als Eingang 57 für das zu pumpende Fluid dienender Stutzen mündet, beispielsweise im untersten Bereich des Behälters 51, in dessen Innenraum 53. Der Endteil 17 besitzt mindestens einen Durchgang 59, nämlich mindestens zwei und vorzugsweise noch mehr um die Achse 45 herum verteilte Durchgänge 59. Diese bilden zusammen mit dem Behälter-Innenraum 53 Fluid-Zuleitmittel 53, 59, die den Eingang 57 mit der Pumpkammer 33 verbinden. Ein plattenförmiges Ventilelement 61 besitzt eine zentrale, zur Achse 45 koaxiale Durchgangsöffnung 61a und ist entlang der Achse 45 und also in der Verschieberichtung des Kolbens 35 verschiebbar in der Pumpkammer 33 geführt, wobei der mögliche Verschiebeweg des Ventilelements 61 auf der einen Seite durch den Endteil 17 des Gehäuses und auf der anderen Seite durch das der Antriebsvorrichtung 3 zugewandte Ende der Erweiterung 15d begrenzt ist. Die Durchgänge 59 dienen zusammen mit dem Ventilelement 61 als erstes Rückschlagventil 63, dessen Ventilsitz durch die dem Kolben 35 zugewandte, ebene Stirnfläche des Endteils 17 gebildet ist.A nozzle serving as an inlet 57 for the fluid to be pumped opens, for example in the lowest region of the container 51, into the interior 53 thereof. The end part 17 has at least one passage 59, namely at least two and preferably even more passages 59 distributed around the axis 45 Together with the container interior 53, these form fluid supply means 53, 59 which connect the inlet 57 to the pump chamber 33. A plate-shaped valve element 61 has a central through-opening 61a which is coaxial with the axis 45 and is guided in the pump chamber 33 so as to be displaceable along the axis 45 and thus in the direction of displacement of the piston 35, the possible displacement path of the valve element 61 on one side through the end part 17 of the housing and on the other side is limited by the end of the extension 15d facing the drive device 3. The passages 59 together with the valve element 61 serve as the first check valve 63, the valve seat of which is formed by the flat end face of the end part 17 facing the piston 35.

Der Endteil 17 des Gehäuses 11 ist ferner mit einem zentralen, zur Achse 45 koaxialen Durchgang 65 versehen, der einen sich von der Pumpkammer 33 weg erweiternden, einen Ventilsitz bildenden Abschnitt aufweist. Im Durchgang 65 ist ein zum Beispiel kugelförmiges Ventilelement 67 bewegbar gehalten, das durch eine Feder 69 gegen den Ventilsitz gedrückt wird. Der Durchgang 65 dient zusammen mit dem Ventilelement 67 und der Feder 69 als zweites Rückschlagventil 71. Eine am Endteil 17 befestigte, dicht mit dem Durchgang 65 verbundene, etwa aus einem Rohr bestehende Leitung 75 führt durch den Behälter-Innenraum 53 hindurch zu einer die Wandung des Behälters 51 durchdringenden Durchführung und bildet dort mit dieser zusammen einen Ausgang 77 für das gepumpte Fluid. Der Durchgang 65 bildet zusammen mit der Leitung 75 Fluid-Ableitmittel 65, 75, welche die Pumpkammer 33 mit dem Ausgang 77 verbinden.The end part 17 of the housing 11 is further provided with a central passage 65 which is coaxial with the axis 45 and which has a section which widens away from the pump chamber 33 and forms a valve seat. In the passage 65, for example, a spherical valve element 67 is movably held, which is pressed against the valve seat by a spring 69. The passage 65 serves together with the valve element 67 and the spring 69 as a second check valve 71. A line 75 fastened to the end part 17 and tightly connected to the passage 65 and consisting, for example, of a tube leads through the container interior 53 to a wall of the container 51 penetrating bushing and forms there together with this an outlet 77 for the pumped fluid. The passage 65 forms, together with the line 75, fluid discharge means 65, 75 which connect the pump chamber 33 to the outlet 77.

Der Durchmesser des an den Kolben 35 anschliessenden Abschnitts der Kolbenstange 39 ist kleiner als der Durchmesser des Kolbens sowie der Buchsen-Innenfläche 15c. Der hülsenförmige Träger 13 ist zwischen der Buchse 15 und der Durchführung 13b mit mindestens einem seinen Mantel durchdringenden Loch 79 und nämlich mit mindestens zwei über seinen Umfang verteilten Löchern 79 versehen. Diese münden in einen freien, die Kolbenstange 39 umschliessenden Bereich des Innenraums 31 des Gehäuses 11. Der Kolben 35 besitzt ein von seiner der Pumpkammer 33 zugewandten Stirnseite her in ihn gebohrtes Sackloch 81. Dieses besitzt einen sich in Richtung zum Endteil 17 des Gehäuses 11 hin konisch erweiternden Mündungsabschnitt, der als Ventilsitz 83 dient. Der Kolben ist auf seiner der Antriebsvorrichtung 3 zugewandten und der Pumpkammer 33 abgewandten Seite zwischen seiner zylindrischen Mantelfläche und der Kolbenstange 39 durch eine konische Ringfläche begrenzt, von der aus geneigte Löcher 85 in den Kolben gebohrt sind, die in den Grundabschnitt des Sacklochs 81 münden. In dieses ist zwischen dessen Grundabschnitt und dem Ventilsitz 83 ein Führungskörper 87 eingesetzt, der im mittleren Teil einen buchsen-und/oder nabenartigen Mittelabschnitt aufweist. Von diesem ragen um ihn herum verteilte, rippen- oder flügelartige Vorsprünge nach aussen, deren freie Ränder in das Sackloch 81 eingepresst sind und den Führungskörper in diesem festhalten, wobei eventuell noch zusätzliche Sicherungsmittel und/oder Befestigungsmittel vorhanden sind, um den Führungskörper 87 zu sichern und starr im Kolben zu fixieren. Zwischen den einander benachbarten, rippen- oder flügelartigen Vorsprüngen des Führungskörpers sind um dessen nabenartigen Mittelabschnitt herum verteilte Kanäle 89 vorhanden. Die Anzahl Kanäle 89 ist beispielsweise gleich der Anzahl Löcher 85 und kann zum Beispiel je nach der Grösse und vorgesehenen Förderleistung der Pumpe etwa vier bis acht betragen. Ein Ventilelement 91 hat einen zur Achse 45 koaxialen Teller mit einem konischen, in den konischen Ventilsitz 83 hineinpassenden Abschnitt und auf seiner dem Endteil 17 zugewandten Seite einen kurzen, zylindrischen Vorsprung, dessen Durchmesser etwas kleiner ist als der Durchmesser der Durchgangsöffnung 61a des Ventilelements 61 des ersten Rückschlagventils. Das Ventilelement 91 ist starr mit einem Bolzen 93 verbunden und beispielsweise mit diesem zusammen aus einem einstückigen Körper gebildet. Der Bolzen 93 durchdringt das Führungsloch 87a des Führungskörpers 87, ist in diesem parallel zur Verschieberichtung des Kolbens verschiebbar geführt und an seinem dem Ventilelement 91 abgewandten Ende mit einem Gewinde versehen, auf das eine Mutter 95 aufgeschraubt ist. Zwischen dieser und dem nabenartigen Mittelabschnitt des Führungskörpers 87 ist mindestens eine Feder 97, nämlich eine den Bolzen 93 umschliessende Schraubenfeder angeordnet, die auf die Mutter 95 und über den Bolzen 93 eine vom Endteil 17 weg zur Antriebsvorrichtung 3 hin gerichtete Kraft auf das Ventilelement 91 ausübt. Die freien Bereiche des Sacklochs 81 bilden zusammen mit den Löchern 85 und den Kanälen 89 einen Durchgang. Dieser verbindet den zwischen dem Kolben 35 und der Durchführung 13b vorhandenen, freien Bereich des Gehäuse-Innenraums 31 durch den Kolben 35 hindurch fluidmässig mit der Pumpkammer 33 und bildet zusammen mit dem in ihm vorhandenen Ventilsitz 83, dem Ventilelement 91, dem Bolzen 93, der Mutter 95 und der Feder 97 ein drittes, das Einströmen von Fluid in die Pumpkammer 33 ermöglichendes Rückschlagventil 99.The diameter of the section of the piston rod 39 adjoining the piston 35 is smaller than the diameter of the piston and of the inner surface 15c of the bush. The sleeve-shaped carrier 13 is provided between the bushing 15 and the bushing 13b with at least one hole 79 penetrating its jacket, namely with at least two holes 79 distributed over its circumference. These open into a free area of the interior 31 of the housing 11 that surrounds the piston rod 39. The piston 35 has a blind hole 81 drilled into it from its end facing the pump chamber 33. This has a hole in the direction of the end part 17 of the housing 11 conically widening mouth section, which serves as valve seat 83. The piston on its side facing the drive device 3 and facing away from the pumping chamber 33 between its cylindrical outer surface and the piston rod 39 is delimited by a conical annular surface, from which inclined holes 85 are drilled in the piston, which open into the base section of the blind hole 81. In this, a guide body 87 is inserted between the base section and the valve seat 83, which has a bushing and / or has hub-like middle section. From this, rib-like or wing-like projections distributed around it protrude outward, the free edges of which are pressed into the blind hole 81 and hold the guide body therein, additional securing means and / or fastening means possibly being present to secure the guide body 87 and rigidly fixed in the piston. Channels 89 are distributed between the mutually adjacent, rib-like or wing-like projections of the guide body around its hub-like central section. The number of channels 89 is, for example, equal to the number of holes 85 and can be, for example, approximately four to eight, depending on the size and intended delivery capacity of the pump. A valve element 91 has a plate which is coaxial with the axis 45 and has a conical section which fits into the conical valve seat 83 and on its side facing the end part 17 has a short, cylindrical projection, the diameter of which is somewhat smaller than the diameter of the through opening 61a of the valve element 61 first check valve. The valve element 91 is rigidly connected to a bolt 93 and, for example, is formed together with this from a one-piece body. The bolt 93 penetrates the guide hole 87a of the guide body 87, is displaceably guided therein parallel to the direction of displacement of the piston and is provided with a thread on its end facing away from the valve element 91, onto which a nut 95 is screwed. Between this and the hub-like central section of the guide body 87 there is at least one spring 97, namely a helical spring surrounding the bolt 93, which exerts a force on the nut 95 and on the bolt 93 a force directed away from the end part 17 towards the drive device 3 on the valve element 91 . The free areas of the blind hole 81 form a passage together with the holes 85 and the channels 89. This connects the free area of the housing interior 31 between the piston 35 and the bushing 13b fluidly through the piston 35 to the pump chamber 33 and, together with the valve seat 83, the valve element 91, the bolt 93, forms the nut 95 and the spring 97, a third check valve 99, which allows fluid to flow into the pump chamber 33.

Das Gehäuse 11 besteht zumindest im wesentlichen aus metallischen, vorzugsweise aus rostfreiem Stahl hergestellten Teilen, wobei die Buchse 15 beispielsweise aus gehärtetem rostfreien Stahl besteht. Der Kolben 35 besteht beispielsweise aus einer Beryllium-Kupfer-Legierung. Das Ventilelement 61 besteht etwa aus rostfreiem Stahl, das Ventilelement 67 aus metallischem Material, etwa ebenfalls rostfreiem Stahl, und/oder Polytetrafluoräthylen und das Ventilelement 91 aus einem metallischen Material, wie einer Beryllium-Kupfer-Legierung oder der unter dem Namen Monel bekannten Kupfer-Nickel-Legierung.The housing 11 consists at least essentially of metallic, preferably made of stainless steel parts, the bushing 15 being made, for example, of hardened stainless steel. The piston 35 consists, for example, of a beryllium-copper alloy. The valve element 61 is made of, for example, stainless steel, the valve element 67 is made of metallic material, such as stainless steel, and / or polytetrafluoroethylene, and the valve element 91 is made of a metallic material, such as a beryllium-copper alloy or the copper known under the name Monel. Nickel alloy.

Beim Betrieb der Pumpe wird der Eingang 57 beispielsweise mit einem Reservoir verbunden, welches das zu pumpende Fluid, d.h. verflüssigtes Gas enthält. Der im Reservoir vorhandene Druck ist mindestens gleich dem UmgebungsLuftdruck und vorzugsweise etwas grösser als dieser, so dass das Fluid durch den im Reservoir vorhandenen Druck zum Eingang 57 der Pumpe und in den Innenraum 53 von deren Behälter 51 hineingedrückt wird. Der Behälter 51 ist noch mit einem Gasablass 101 versehen, dessen inneres Ende sich in der Nähe des obersten Bereichs des Behälter-Innenraums 53 befindet. Der Gasablass 101 ist beispielsweise über eine Gas-Rückleitung mit dem erwähnten Reservoir oder über ein Uberdruckventil mit der Umgebung verbunden. Der Ausgang 77 für das verflüssigte und mit der Pumpe verdichtete Gas kann beispielsweise mit einer Verdampfungs- und Füllvorrichtung verbunden sein, um das nun wieder gasförmige, aber stark verdichtete Fluid in einen Druckbehälter abzufüllen.When the pump is operating, the input 57 is connected, for example, to a reservoir which contains the fluid to be pumped, ie liquefied gas. The pressure present in the reservoir is at least equal to the ambient air pressure and preferably somewhat greater than this, so that the fluid is pressed into the reservoir 57 to the inlet 57 and into the interior 53 of its container 51 by the pressure present in the reservoir. The container 51 is also provided with a gas outlet 101, the inner end of which is in the vicinity of the uppermost region of the container interior 53. The gas outlet 101 is connected, for example, to the aforementioned reservoir via a gas return line or to the surroundings via a pressure relief valve. The outlet 77 for the liquefied and compressed by the pump gas can, for example, with an evaporation and filling device be connected to fill the now gaseous but highly compressed fluid in a pressure vessel.

Beim Betrieb der Pumpe strömt durch den Eingang 57 mindestens zur Hauptsache aus verflüssigtem Gas bestehendes Fluid in den Innenraum 53 des Behälters 51. Das verflüssigte Gas steigt im Behälter beispielsweise bis zum Niveau 111, über dem sich dann durch Verdampfen wieder in den gasförmigen Aggregatszustand gelangtes, in der Figur 1 durch Blasen angedeutetes Fluid befindet. Die sich innerhalb des Behälter-Innenraums 53 befindenden Teile des Gehäuses 11 und also insbesondere dessen Buchse 15 und Endteil 17, die zusammen den eigentlichen Pumpzylinder bilden, sind beim Betrieb der Pumpe von unter Niederdruck stehendem, d.h. vom Eingang zugeführtem, noch nicht gepumptem, verflüssigtem Gas umgeben. Die beim Pumpen infolge der Reibung des Kolbens 35 in der Buchse 15 erzeugte Reibungswärme sowie auch die von der Kolbenstange 39 in der Durchführung 13b erzeugte Reibungswärme und die allenfalls in der Pumpkammer 33 sowie den drei Rückschlagventilen erzeugte Wärme kann daher zu einem grossen Teil an das im Behälter-Innenraum 53 vorhandene, unter Niederdruck stehende, verflüssigte Gas abgegeben werden, wobei diese Wärme dann als Verdampfungswärme verbraucht und mit dem dabei entstehenden Dampf aus dem Behälter 51 abtransportiert wird.During operation of the pump, fluid consisting at least mainly of liquefied gas flows into the interior 53 of the container 51 through the inlet 57. The liquefied gas rises in the container, for example, to level 111, above which level evaporation then returns to the gaseous state. fluid indicated by bubbles in FIG. 1. The parts of the housing 11 located within the container interior 53, and in particular its bush 15 and end part 17, which together form the actual pump cylinder, are of low pressure, i.e. surrounded by the feed, not yet pumped, liquefied gas. The frictional heat generated during pumping as a result of the friction of the piston 35 in the bushing 15, as well as the frictional heat generated by the piston rod 39 in the bushing 13b and the heat generated at most in the pumping chamber 33 and the three check valves can therefore to a large extent be attributed to the im Container interior 53 existing, under low pressure, liquefied gas are released, this heat then being consumed as heat of evaporation and being transported away from the container 51 with the resulting steam.

Beim Pumpen schiebt die Antriebsvorrichtung 3 den Kolben 35 abwechselnd entlang der horizontalen Achse 45 hin und her. Wenn sich der Kolben im nachfolgend als Saugtakt bezeichneten Zeitintervall in den Figuren 1 und 2 nach links, d.h. vom Endteil 17 weg bewegt, wie es beim Zeichnen der Ventilelemente angenommen wurde, saugt er in der durch Pfeile angedeuteten Weise Fluid aus dem Behälter-Innenraum 53 durch das erste Rückschlagsventil 63 sowie durch die Löcher 79 und den Durchgang des dritten Rückschlagventils 99 in die Pumpkammer 33 hinein. Wenn sich der Kolben dann im nachfolgend als Verdichtungstakt bezeichneten Zeitintervall in der entgegengesetzten Richtung bewegt, drückt er Fluid aus der Pumpkammer 33 heraus über das zweite Rückschlagventil 71 zum Ausgang 77.When pumping, the drive device 3 alternately pushes the piston 35 back and forth along the horizontal axis 45. If the piston moves to the left in FIGS. 1 and 2, ie away from the end part 17 in the time interval referred to below as the suction stroke, as was assumed when drawing the valve elements, it sucks fluid out of the container interior 53 in the manner indicated by arrows through the first check valve 63 as well as through the holes 79 and the passage of the third Check valve 99 into the pump chamber 33. If the piston then moves in the opposite direction in the time interval referred to below as the compression stroke, it pushes fluid out of the pump chamber 33 via the second check valve 71 to the outlet 77.

Nachdem die allgemeine Arbeitsweise der Pumpe beschrieben wurde, sollen nun noch einige Einzelheiten des Pumpvorgangs näher erläutert werden. Im Verdichtungstakt, in dem sich der Kolben 35 zum Endteil 17 hin bewegt, presst das in der Pumpkammer 33 vorhandene Fluid das Ventilelement 61 an den Gehäuse-Endteil 17 und das Ventilelement 91 in den Kolben 35 hinein gegen den Ventilsitz 83, so dass das erste Rückschlagventil 63 sowie das dritte Rückschlagventil 99 geschlossen sind, während das zweite Rückschlagventil 71 selbstverständlich offen ist. Die Feder 97 ist so bemessen, dass sie nur eine verhältnismässig kleine Kraft erzeugt, die gerade ausreicht, um das Ventilelement 91, wenn keine anderen Kräfte auf dieses einwirken, zum Anliegen am Ventilsitz 83 zu bringen. Wenn nun der Kolben 35 am Ende eines Verdichtungstaktes bis zum Stillstand abgebremst und dann am Anfang des Saugtaktes in der vom Endteil 17 weg verlaufenden Richtung beschleunigt wird, sind die durch die Trägheit auf das Ventilelement 91 ausgeübten Kräfte bestrebt, das Ventilelement 91 vom Ventilsitz 83 abzuheben. Diese Trägheitskräfte werden dann noch durch den Staudruck des sich auf der linken Seite des Ventilelements 91 befindenden Fluids unterstützt. Dies hat zur Folge, dass das dritte Rückschlagventil 99 am Anfang eines Saugtaktes sehr rasch geöffnet wird. Dadurch kann weitgehend vermieden werden, dass in der besonders kritischen Anfangsphase des Saugtaktes in der Pumpkammer ein das Verdampfen von verflüssigtem Gas bewirkender Druckabfall entsteht. Wenn sowohl das erste als auch das dritte Rückschlagventil offen sind, ergeben sie zusammen einen verhältnismässig grossen Durchlassquerschnitt, was der Entstehung von Druckabfällen und dem Verdampfen von verflüssigtem Gas ebenfalls entgegenwirkt. Die bereits erwähnte Tatsache, dass beim Pumpen in der Pumpkammer 33 und deren Umgebung durch Reibung und/oder in anderer Weise erzeugte Wärme an das im Behälter-Innenraum 53 vorhandene, die Buchse 15 und den Endteil 17 umgebende, verflüssigte Gas abgegeben werden kann, hilft ebenfalls mit, das Verdampfen von verflüssigtem, sich in der Pumpkammer befindendem Gas zu vermeiden.After the general operation of the pump has been described, some details of the pumping process will now be explained in more detail. In the compression stroke, in which the piston 35 moves towards the end part 17, the fluid present in the pump chamber 33 presses the valve element 61 against the housing end part 17 and the valve element 91 into the piston 35 against the valve seat 83, so that the first Check valve 63 and the third check valve 99 are closed, while the second check valve 71 is of course open. The spring 97 is dimensioned such that it generates only a relatively small force which is just sufficient to bring the valve element 91 into contact with the valve seat 83 if no other forces act on it. If, at the end of a compression stroke, the piston 35 is braked to a standstill and then accelerated at the beginning of the suction stroke in the direction extending from the end part 17, the forces exerted on the valve element 91 by inertia tend to lift the valve element 91 from the valve seat 83 . These inertial forces are then supported by the dynamic pressure of the fluid located on the left side of the valve element 91. The result of this is that the third check valve 99 is opened very quickly at the beginning of a suction cycle. This largely prevents the pressure drop from evaporating liquefied gas from occurring in the pumping chamber in the particularly critical initial phase of the suction cycle. When both the first and third check valves are open, they together make one proportionate large passage cross-section, which also counteracts the development of pressure drops and the vaporization of liquefied gas. The fact already mentioned that during pumping in the pump chamber 33 and its surroundings, heat generated by friction and / or in some other way can be given off to the liquefied gas which is present in the container interior 53 and surrounds the bush 15 and the end part 17 also to avoid the evaporation of liquefied gas in the pumping chamber.

Das Ventilelement 91 kann beispielsweise derart ausgebildet sein, dass die dem Endteil 17 zugewandte Ringfläche seines konischen Abschnitts, wenn es in seiner Schliessstellung am Ventilsitz 83 anliegt, etwa bündig mit der Stirnfläche des Kolbens ist. Ferner kann der Verschiebeweg des Kolbens derart festgelegt werden, dass er und die genannte Ringfläche des Ventilelements 91 am Ende des Verdichtungstaktes, wenn das Ventilelement 61 am Endteil 17 anliegt, ihrerseits mindestens annähernd am Ventilelement 61 anliegen und dass der Vorsprung des Ventilelements 91 in die zentrale Öffnung 61a des Ventilelements 61 hinein ragt. Wenn diese Bedingungen erfüllt sind, wird das freie Volumen der Pumpkammer am Ende des Verdichtungstaktes nahezu auf Null reduziert, so dass sich in der Pumpkammer 33 und zwischen dieser und den Ventilsitzen der drei Rückschlagventile praktisch kein toter Raum ergibt.The valve element 91 can, for example, be designed such that the annular surface of its conical section facing the end part 17, when it rests on the valve seat 83 in its closed position, is approximately flush with the end face of the piston. Furthermore, the displacement path of the piston can be determined such that it and the said annular surface of the valve element 91 at the end of the compression stroke, when the valve element 61 abuts the end part 17, in turn lie at least approximately on the valve element 61 and that the projection of the valve element 91 into the central one Opening 61a of valve element 61 projects into it. If these conditions are met, the free volume of the pumping chamber is reduced to almost zero at the end of the compression stroke, so that there is practically no dead space in the pumping chamber 33 and between it and the valve seats of the three check valves.

Die Pumpe kann selbstverständlich in verschiedener Hinsicht modifiziert werden. Beispielsweise kann der Eingang 57 statt radial - wie in Figur 1 gezeichnet - parallel zur Kolbenachse durch die sich in der Figur 1 rechts befindende Stirnwand des Behälters 51 hindurch in dessen Innenraum 53 einmünden. Ferner kann dann im Innenraum des Behälters zwischen dem Eingang 57 und den Durchgängen des ersten und dritten Rückschlagventils noch ein Filtersieb angeordnet sein, das zur Erzielung einer grossen Oberfläche beispielsweise konusförmig ausgebildet sein kann. Zudem können die Durchgänge der drei Rückschlagventile und deren übrige Ausbildung auf manigfaltige Weise geändert werden. Der als Stirnwand des Gehäuses 11 dienende Endteil 17 kann zum Beispiel durch einen - in axialer Richtung gemessen - dickeren Endteil ersetzt werden, dessen Mantelfläche mit einer Ringnut versehen ist, die sich von ihrem Grund nach aussen erweitert. Die den Durchgängen 59 entsprechenden Durchgänge können dann bei ihren der Pumpkammer 33 abgewandten Enden statt wie bei der Figur 2 in die der Buchse 15 abgewandte Stirnfläche des Endteils 17 in die in dessen Mantelfläche vorhandene Ringnut münden.The pump can of course be modified in various ways. For example, instead of radially — as drawn in FIG. 1 — the inlet 57 can open parallel to the piston axis through the end wall of the container 51 located on the right in FIG. 1 and into its interior 53. Furthermore, then in the interior of the container between the inlet 57 and the passages of the first and third check valve, a filter screen can also be arranged, which can be conical, for example, to achieve a large surface area. In addition, the passages of the three check valves and their remaining training can be changed in a variety of ways. The end part 17 serving as the end wall of the housing 11 can be replaced, for example, by a thicker end part, measured in the axial direction, the outer surface of which is provided with an annular groove which widens outwards from the bottom thereof. The passages corresponding to the passages 59 can then, at their ends facing away from the pump chamber 33, open into the end face of the end part 17 facing away from the bushing 15 into the annular groove provided in the lateral surface thereof, as in FIG.

Ferner kann stattdessen oder zusätzlich zum Beispiel mindestens eine Feder vorgesehen werden, die das bewegbare Ventilelement des ersten Rückschlagventils mit einer vom Kolben 35 weg zum Gehäuse-Endteil 17 hin gerichteten Kraft beaufschlägt. Das Ventilelement des ersten Rückschlagventils kann zu diesem Zweck beispielsweise auf seiner dem Kolben abgewandten Seite mit mindestens einem in ein Loch des Gehäuses-Endteils hineinragenden Finger versehen sein, auf dessen dem Kolben abgewandten Ende eine Mutter aufgeschraubt ist. Auf dem Finger kann dann eine Schraubenfeder gehalten sein, die einenends an einer Radialfläche des Gehäuse-Endteils und anderenends an der besagten Mutter angreift. Das den Finger aufnehmende und führende Loch des Gehäuse-Endteils kann beispielsweise koaxial zum Kolben im Gehäuse-Endteil und also an der Stelle angeordnet sein, an der sich in der Figur 2 der Durchgang 65 des zweiten Rückschlagventils befindet. In diesem Fall könnte der Durchgang des zweiten Rückschlagventils dann beispielsweise in radialer Richtung durch den Mantel der Buchse 15 hindurch in die Pumpkammer 33 einmünden.Furthermore, instead of or in addition, for example, at least one spring can be provided which acts on the movable valve element of the first check valve with a force directed away from the piston 35 towards the housing end part 17. For this purpose, the valve element of the first check valve can be provided, for example, on its side facing away from the piston with at least one finger protruding into a hole in the housing end part, onto the end of which a nut is screwed away from the piston. A helical spring can then be held on the finger, which engages on one end on a radial surface of the housing end part and on the other end on said nut. The finger-receiving and guiding hole of the housing end part can be arranged, for example, coaxially to the piston in the housing end part and therefore at the point at which the passage 65 of the second check valve is located in FIG. In this case, the passage of the second check valve could then, for example open in the radial direction through the jacket of the bushing 15 into the pump chamber 33.

Des weiteren kann das bewegbare Ventilelement 67 des zweiten Rückschlagventils 71 statt aus einer Kugel aus einem anders geformten Körper, zum Beispiel aus einer Hülse bestehen, die am ventilsitzseitigen Ende durch eine Stirnwand abgeschlossen ist und in deren anderes, offenes Ende eine der Feder 69 entsprechende Feder angreift.Furthermore, the movable valve element 67 of the second check valve 71 can consist of a differently shaped body, for example a sleeve, instead of a ball, which is closed at the valve seat end by an end wall and in the other, open end of a spring corresponding to the spring 69 attacks.

Der zur Führung des Bolzens 93 des dritten Rückschlagventils dienende Führungskörper 87 kann aus einer Buchse gebildet sein, die aussen eine rund um ihre Achse herum zusammenhängende, zylindrische Mantelfläche besitzt. Die Buchse kann analog wie es für den Führungskörper 87 beschrieben ist, in das Sackloch 81 eingepresst und im Kolben zusätzlich mit Sicherungs-und/oder Befestigungsmitteln fixiert sein. Die letzteren können zum Beispiel mindestens eine Madenschraube und beispielsweise mehrere solche aufweisen, die unter einer der Dichtungen des Kolbens über dessen Umfang verteilt in radiale Gewindebohrungen des Kolbenmantels eingeschraubt sind und mit ihren der Kolbenachse zugewandten, beispielsweise kegelförmigen Enden in Löcher der den Führungskörper bildenden Buchse eingreifen. Die in der Figur 2 ersichtlichen Kanäle 89 können dann durch um die Achse und das dem Führungsloch 87a entsprechende Loch der Buchse herum verteilte Löcher, vorzugsweise Bohrungen gebildet sein.The guide body 87 used to guide the bolt 93 of the third check valve can be formed from a bushing which has a cylindrical outer surface that is connected around its axis. The bushing can be pressed into the blind hole 81 in a manner analogous to that described for the guide body 87 and additionally fixed in the piston with securing and / or fastening means. The latter can have, for example, at least one grub screw and, for example, several such, which are screwed in under one of the seals of the piston distributed over its circumference in radial threaded bores of the piston jacket and engage with their, for example, conical ends facing the piston axis in holes in the bushing forming the guide body . The channels 89 shown in FIG. 2 can then be formed by holes, preferably bores, distributed around the axis and the hole of the bush corresponding to the guide hole 87a.

Claims (10)

  1. Pump for the pumping of a fluid comprising liquified gas, with an inlet (57) as well as an outlet (77) for the fluid, a housing (11) comprising an end member (17) and containing an interior space (31), a piston (35) displaceably guided in the interior space (31) and displaceable alternately away from the end member (17) and towards this, fluid feed means (53, 59) comprising a first non-return valve (63) and connecting the inlet (57), through the end member (17), with a pump chamber (33), which is present between the end member (17) and the piston (35), of the interior space (31), and fluid discharge means (65, 75) comprising a second non-return valve (71) and connecting the pump chamber (33) with the outlet (77), wherein the first non-return valve (63) is constructed to enable the inflow of fluid into the pump chamber (33) when the piston (35) is moving away from the end member (17) and wherein the second non-return valve (71) is constructed to allow fluid to flow out of the pump chamber when the piston (35) is approaching the end member (17), characterised thereby that the piston (35) comprises a third non-return valve (99), by way of which the inlet (57) is connected with the pump chamber (33) and which is constructed to enable the inflow of fluid into the pump chamber (33) when the piston (35) is moving away from the end member (17).
  2. Pump according to claim 1, characterised thereby that the third non-return valve (99) comprises a valve seat (83) fixed in relation to the piston (35) and a valve element (91), which in a closing setting lies against the valve seat (83) and is movable away from this in direction towards the end member (17).
  3. Pump according to claim 2, characterised by a spring (97) which exert upon the valve element (91) of the third non-return valve (99) a force directed towards the valve seat (83) thereof.
  4. Pump according to claim 2 or 3, characterised thereby that the piston (35) possesses at its end bounding the pump chamber (33) a depression forming the valve seat (83) of the third non-return valve (99), that the valve element (91) of the third non-return valve (99) is connected with a bolt (93), that a guide hole (87a) displaceably guiding the bolt (93) is present in the piston (35) and that the depression is connected with the inlet (57) by way of at least two channels (89) present in the piston (35) and distributed around the guide hole (87).
  5. Pump according to one of claims 1 to 4, characterised thereby that the inlet (57) is connected fluidwise with a region, located at the side of the piston (35) facing away from the end member (17), of the interior space (31) of the housing (11) and that the third nonreturn valve (99) possesses a passage (81, 85, 89), passing through at least a part of the piston (35), with at least one hole (85) opening into the said region of the interior space and preferably at least two such holes (85), of which the openings, opening into the said region of the interior space, are distributed around the axis (45) of the piston (35) and for example around a piston rod (39) connecting the piston with a drive device (3).
  6. Pump according to one of claims 1 to 5, characterised thereby that the first non-return valve (63) comprises at least one passage (59) penetrating the end member (17) from the side thereof facing away from the pump chamber (33) to the surface thereof bordering the pump chamber and a valve element (61) movably held in the displacement direction of the piston (35), wherein the first nonreturn valve (63) preferably possesses several straight passages (59) distributed around the axis (45) of the piston (35).
  7. Pump according to one of claims 1 to 6, characterised thereby, that the fluid discharge means (65, 75) comprise a passage (65) penetrating the end member (17), which passage forms a valve seat for the second non-return valve (71) and contains a movable valve element (67) which is associated therewith and at which a spring (69) preferable engages, wherein this passage (65) of the fluid discharge means (65, 75) is preferably arranged coaxially with the axis (45) of the piston (35), the valve element (61) of the first non-return valve (63) is preferably arranged in the pump chamber(33) between the end member (17) and the piston (35), as well as has a passage opening (61a) coaxial with the longitudinal central axis (45) of the piston (35), and the first non-return valve (63) preferably comprises at least two passages (59) penetrating the end member (17) and distributed around the passage (65) of the fluid discharge means (65, 75).
  8. Pump according to one of claims 1 to 7, characterised thereby that at least the end member (17) and that remaining part (15) of the housing (11) of which the inner surface comes into contact with the piston (35) are disposed in the interior space (53) of a vessel (51) possessing at least partly a heat insulating wall, that the inlet (57) is connected, by way of the interior space (53) of the vessel (51), with the first non-return valve (63) as well as with the third non-return valve (99) and that the vessel (51) possesses a gas outlet (101) for the blowing out of fluid getting into the gaseous physical state.
  9. Pump according to claim 8, characterised thereby, that the axis (45) of the piston (35) is horizontal and is disposed below the likewise horizontal axis (55) of the vessel (51).
  10. Pump according to one of claims 1 to 9, characterised thereby that it comprises the said piston (35) exclusively and no other piston.
EP88810290A 1987-05-19 1988-05-04 Pump for fluid including liquified gas Expired - Lifetime EP0294322B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH1923/87A CH672354A5 (en) 1987-05-19 1987-05-19
CH1923/87 1987-05-19

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EP0294322A2 EP0294322A2 (en) 1988-12-07
EP0294322A3 EP0294322A3 (en) 1990-02-28
EP0294322B1 true EP0294322B1 (en) 1993-01-27

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EP (1) EP0294322B1 (en)
CH (1) CH672354A5 (en)
DE (1) DE3877832D1 (en)

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DE3877832D1 (en) 1993-03-11
CH672354A5 (en) 1989-11-15
US4915602A (en) 1990-04-10
EP0294322A2 (en) 1988-12-07
EP0294322A3 (en) 1990-02-28

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