US3838944A - Diaphragm pumps with pressure equalising chambers - Google Patents

Abstract

A diaphragm pump which can function as a pressure pump or a suction pump and which is for use in aerating aquaria or in medical and industrial apparatus, has a pump housing which is longer in one direction than in another and which is divided longitudinally to form a pump chamber in which the pumping mechanism is located and a pressure equalising chamber through which the pump output is passed. The division of the housing longitudinally to provide an elongated pressure equalising chamber is very effective in providing the pump with a fairly continuous and relatively silent output, particularly when the effective distance between the inlet and the outlet of the equalising chamber is at least half the length of the chamber.

Description

United States Patent 1191 Kolfertz 1 1 DIAPHRAGM PUMPS WITH PRESSURE EQUALISING CHAMBERS [76] Inventor: Erwin Kolfertz, Bebelallee 9,

Solingen-Merscheid, Germany [22] Filed: Aug. 21, 1972 21 Appl. No; 282,322

[30] Foreign Application Priority Data 1111 3,838,944 Oct. 1, 1974 3,671,151 6/1972 Duke 417/540 X FOREIGN PATENTS OR APPLICATIONS 589,713 6/1925 France Primary Examiner-C. J. Husar Assistant Examiner-Leonard Smith Attorney, Agent, or FirmToren and McGeady [5 7] ABSTRACT A diaphragm pump which can function as a pressure pump or a suction pump and which is for use in aerating aquaria or in medical and industrial apparatus, has a pump housing which is longer in one direction than in another and which is divided longitudinally to form a pump chamber in which the pumping mechanism is located and a pressure equalising chamberthrough which the pump output is passed. The division of the housing longitudinally to provide an elongated pressure equalising chamber is very effective in providing the pump with a fairly continuous and relatively silent output, particularly when the effective distance between the inlet and the outlet of the equalising chamber is at least half the length of the chamber.

5 Claims, 4 Drawing Figures DIAPHRAGM PUMPS WITH PRESSURE EQUALISING CHAMBERS This invention relates to diaphragm pumps which can function as a pressure pump or a suction pump, and which are commonly used for aerating aquaria and for medical and industrial apparatus. the pumps having a pressure equalising chamber for equalising the pressure of the output from them.

The moving parts of such diaphragm pumps usually consist only of a diaphragm. two valves and an oscillating armature. fluid being sucked into the pump through one of the valves on one stroke of the diaphragm and expelled through the other valve on the other stroke, the two valves acting 180 out of phase. That is, during the period when the fluid is flowing through the one valve the other valve remains closed, and vice versa. The valves are usually simple flap valves, or the equivalent. A pump of this kind has several advantages. There are very few moving parts and are therefore extremely simple, and the pump requires very little maintenance. On the other hand diaphragm pumps have the disadvantage that they are often very noisy, the noise level increasing with increasing pump output.

In an attempt to reduce the noise it is known to pass the pump output through a pressure equalising chamber. The pump housing is usually cylindrical and the known type of pressure equalising chamber is situated in one end of the housing. This arrangement is however so ineffective that it has hardly been used in practice.

The aim of the present invention is to provide a diaphragm pump which operates much more silently and which delivers the fluid substantially evenly and with good efficiency, and according to the invention this is achieved by having a pump housing which is longer in one direction than it is in another and which is divided longitudinally to form the pressure equalising chamber.

This results in an elongated pressure equalising chamber in which the pressure pulses from the diaphragm pump are largely damped out. A particularly good effect is obtained by subdividing the pump housing approximately in the ratio of at least 1:5, the smaller part being arranged as the pressure equalising chamber. In further development of the invention the functioning of the pressure equalising chamber is improved still further if the effective distance between the inlet opening of the pressure equalising chamber and its outlet opening is at least half the length of the chamber. This prevents pressure pulses from travelling directly across the chamber from the inlet opening to the outlet opening. If the inlet opening is situated near the outlet opening, the effective separation can be obtained by connecting a tube to at least one of the openings so that it extends within the pressure equalising chamber for a sufficient distance from the other opening.

The use of a separating tube makes it possible to position the inlet and outlet openings of the pressure equalising chamber opposite each other, so that the inlet opening and the neighbouring wall of the pump housing are therefore readily accessible when the pump is being assembled. In this case, the outlet opening is preferably fitted with a connecting piece having an external connector and an internal connector which communicates with the external connector and which is connected to the separation tube which extends longitudinally within the pressure equalising chamber for a distance of at least half the length of the chamber.

The connecting piece is a press fit in the wall of the pump housing. ensuring a sufficient seal between the connecting piece and the pump housing. Further advantages are obtained. in regard to the functioning of the pressure equalising chamber and in regard to assembly ofthe diaphragm pump and manufacture of the pump housing. in that the pump housing is in the form of a rectangular box with a cover. the contact surfaces between the cover and the body of the pump housing extending over the pressure equalising chamber. The pressure equalising chamber is therefore just as accessible, for example for cleaning purposes, as are the other parts of the pump housing.

The cover has to be well sealed, because it forms a closure both for the pressure equalising chamber and for the other part of the pump housing. i.e.. the pump chamber. Preferably therefore, the cover is sealed by a sealing plate which is approximately the same size as the cover to compensate for inaccuracies in assembly or the like. The cover has at least one opening leading into the interior of the pump housing, for example for admitting air for aerating an aquarium into the pump chamber, these openings of course not communicating with the pressure equalising chamber.

It has been found in practice that the pressure equal ising chamber need not extend over the entire length of the pump housing. To obtain the desired effect it is sufficient if the pressure equalising chamber extends for approximately two-thirds of the length of the pump housing.

In the case of a double-diaphragm pump, i.e., where the pumping parts are duplicated, the pump housing is divided longitudinally into at least one pump chamber and a common pressure equalising; chamber. This common pressure equalising chamber is preferably formed by a pair of chamber sections which communicate with each other and which are formed by a number of longitudinal division walls in the pump housing. The connecting duct connecting the pressure equalising chamber sections together preferably has the same crosssectional shape and area as the sections, and the two chamber sections together with the connecting duct preferably form a U-shaped chamber.

There may be two pump chambers separated from each other by a longitudinal division wall, which may or may not have one or more openings through it, or if desired, a common pump chamber can be used.

It has been found in practice that the pump in accordance with the invention functions equally well as a pressure pump or as a suction pump. Conversion from the one method of operation to the other is done without any modification of the relative positions of the os' cillating arms and the magnets, as is necessary in known pumps.

Two examples of diaphragm pumps in accordance with the invention will not be described with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a single diaphragm pump in accordance with the invention;

FIG. 2 is a section through a part of FIG. I;

FIG. 3 is a section taken along the line III III in FIG. 2 and showing more detail of the part; and,

FIG. 4 is a diagrammatic representation of the pump housing of a double-diaphragm pump in accordance with the invention.

The diaphragm pump shown in H6. 1 has arectangular housing 1 which is subdivided by alongitudinal wall 2 into apump chamber 3 and apressure equalising chamber 4. Thepump chamber 3 contains an AC electromagnct consisting of acoil 6. and acore 5. and a pair ofpole pieces 9. These pole pieces co-operate with apermanent magnet armature 7 which is fixed to the end of anarm 8 so that thearmature 7 can oscillate in thepump chamber 3 at the frequency of theAC magnet 5, 6, 9. Thecoil 6, thecore 5, thepole shoes 9, the oscillatingarmature 7 and thearm 8 together form a motor for driving the pump. The actual pumping part of the pump has apump body 13 which is attached by ascrew 12 to thewall 2 which separates thechamber 3 from thepressure equalising chamber 2. There is also arubber diaphragm 11, which is driven in oscillation with thearm 8 which extends through aprojection 10 at the rear of thediaphragm 11. Thepump diaphragm 11 co-operates with thebody 13 andpumping chamber 52 which communicates through anopening 14 in thewall 2 with thepressure equalising chamber 4.

Between thepump body 13 and thewall 2 there is interposed asealing plate 40, as shown in FIGS. 2 and 3. Thesealing plate 40 has a raisedannular rib 41 which seals around one end of thepump body 13. The sealing plate also has acentral opening 42 for the passage of themounting screw 12, and twofurther openings 43 and 44. The opening 43 registers with theopening 14 in thewall 2, and thepumping chamber 52 in the interior of thepump body 13 communicates through theopenings 43 and 14 with thepressure equalising chamber 4. The opening 44 is an inlet port for the actual pumping part, the opening 44 communicating the interior of thepump body 13 with the rest of the interior of thepump chamber 3. The opening 44 is a comparatively large opening, extending outwards to beyond the outer edge of the raisedrib 41 and inwards to beyond the inner edge of thebody 13 where it overlaps apassage 45 of thepump body 13 which will be called the suction passage.

Flow through thesuction passage 45 and into the pumpingchamber 52 is controlled by aninlet valve plate 46 which is centralised and guided in arecess 48 in thepump body 13. thevalve plate 46 being retained by arubber plug 47 at one of its ends.

Flow out of the pumpingchamber 52 and through theopening 43 of the pump is controlled by anoutlet valve plate 49 which, in a similar manner as theinlet valve 46, is retained by aplug 50 and guided in arecess 51 in thepump body 13. However, theplug 50, in contrast to therubber plug 47, is formed integrally with the sealingplate 40, and this considerably simplifies manufacture of the pump.

Theopening 14 in theintermediate wall 2 functions as the inlet opening of thepressure equalising chamber 4. This chamber has an outlet opening situated in the wall of thepump housing 1 nearly opposite theinlet opening 14. To facilitate assembly of thepump body 13, together with other parts, there is a comparatively large circular opening in the wall of thepump housing 1 around theoutlet opening 15, and a connectingpiece 16 is inserted as a close fit in the large opening. The connectingpiece 16 is formed by a press operation and has, projecting from its outer surface, aconnector 17 containing theoutlet opening 15, and an extension tube may, if desired, be connected to theconnector 17. Afurther connector 18 projects inwards into thepressure equalising chamber 4 from the inside of thepiece 16 and mounted over the inner end of theconnector 18 is a length ofstiff tubing 19 which extends almost as far as the remote end of thepressure equalising chamber 4. Consequently air entering the pressure equalising chamber through itsinlet opening 14 flows along at least halfthe'length of thepressure equalising chamber 4 before entering the end of thetube 19 and flowing through the tube and out of the pressure equalising chamber through theconnectors 18 and 17.

Theconnector 18 is preferably bent to allow astraight tube 19 to be used and ensure that thetube 19 cannot become kinked. Theconnector 17 is sunk into the connectingpiece 16 so that when an extension tube is mounted over theconnector 17 and pushed home against the connecting piece 16 a visually clean connection is made. The connectingpiece 16 can be inserted into the large opening in the wall of thepump housing 1 either by hand or by forcing it in with a mechanical, hydraulic or pneumatic tool.

Thepressure equalising chamber 4 damps out the pressure pulses produced by the diaphragm pump so that. in contrast to conventional diaphragm pumps. air. for example, is delivered through the outlet opening 15 at approximately constant pressure and with negligible noise. The noise can if desired be still further reduced by filling thepressure equalising chamber 4 with a fibrous material, such as a felt. cotton wool or horsehair.

The diaphragm pump shown in FIG. 1 can-be used as a pressure pump or it can. if desired, easily be converted into a suction pump by fitting the inlet opening 22 in the wall of thepump housing 1, which is shown in FIG. 1 closed by a plug 23, with a connector to which can be connected a suction line, thepump chamber 3 being well sealed against suction. The suction connector is preferably in the form of a connecting piece similar to the connectingpiece 16, but without the angled insideconnector 18. The suction connector is preferably of a different colour to distinguish it from the connectingpiece 16 and prevent confusion between the two.

In FIG. 4 a double-diaphragm pump is shown having apump housing 30 which consists essentially of twopump housings 1 similar to that of FIG. 1 arranged symmetrically as mirror images on either side of a symmetry axis defined by acommon dividing wall 37. Thiswall 37 separates the two pump chambers from each other but is terminated to allow the two pressure equalising chambers to communicate. However, if desired, thewall 37 may be pierced. or the two pump chambers can communicate entirely with each other. The communicating passage between the two pressure equalising chambers is shown at 31 and has the same crosssection as the main pressure equalising chambers, i.e.. the same as that of thechamber 4 of thepump housing 1 in FIG. 1. In contrast to thepressure equalising chamber 4 of thepump housing 1, thepressure equalising chamber 4 of thepump housing 1, the pressure equalising chamber of thedouble pump housing 30 has two inlet openings, one from each pump chamber, and also twooutlet openings 15. The two pump chambers each contain a diaphragm pump and oscillating armature drive system similar in construction to those of FIGS. 1 to 3.Inlet openings 33 in the external wall of thedouble pump housing 30 allow air to flow into the pump chambers from where is is expelled into the pressure equalising chamber, as in the case of the diaphragm pump of FIG. 1.

The pump housings l and 30 are closed, when the pump is ready for operation, by covers which are not shown in the drawings. In each case the cover meets the pump housing in the plane of the drawing. The cover is a flat plate with a raised edge, the same width and length as the pump housing. The cover is screwed to the housing at the locations shown at 34 in FIG. 4, a sealing plate being interposed to make a good seal. In FIG. 4 the cover has openings indicated by chain lines at 36, near the diaphragm pumps and their oscillating armature drives.

As already mentioned these pumps can be used either as pressure pumps or as suction pumps. The effectiveness of the pump in accordance with the invention is confirmed by the surprising effect that the same pressure difference is obtained on the delivery side as on the intake side of the pump.

I claim:

1. in a diaphragm pump capable of operation either as a pressure pump or a suction pump, said pump including a housing, fluid inlet and outlet means for said housing, and a pumping mechanism including diaphragm means arranged within said housing for pumping a fluid therethrough and drive means for actuating said diaphragm means, the improvement comprising a division wall located interiorly of said housing dividing said housing internally into a pump chamber and a pressure equalization chamber, said housing being structured in a longitudinal configuration with a length dimension greater than the dimensions extending transversely thereof, said partition wall being located to extend longitudinally of said housing, means defining inlet and outlet openings to said pressure equalization chamber, the effective separation between said inlet and said outlet openings being at least half the length of said pressure equalization chamber. a separating tube and means connecting said separating tube to one of said inlet and said outlet openings of said pressure equalization chamber whereby said separating tube extends within said pressure equalization chamber for a sufficient distance to provide said effective separation between said inlet and said outlet openings.

2. A diaphragm pump as inclaim 1, including means mounting said pumping mechanism on said division wall forming said pressure equalising chamber, a sealing plate interposed between said pumping mechanism and said division wall, and said pumping mechanism including a valve plate, means locating said valve plate. and plug means retaining said valve plate in location, said plug means being formed integrally with said sealing plate.

3. A diaphragm pump as inclaim 1, wherein said means defining said actual inlet and outlet openings of said pressure equalising chamber are situated opposite each other in said longitudinal division wall and the wall of said housing respectively, and said separating tube extends for a distance of at least half the length of said pressure equalising chamber.

4. A diaphragm pump as inclaim 3, wherein said separating tube is connected to said outlet opening, and said means connecting said tube to said opening comprises a connecting piece fitted in said opening and having an external connector and an internal connector which communicates with said external connector, and means connecting said separating tube to said internal connector.

5. A diaphragm pump as inclaim 4, wherein said internal connector is bent to provide an end extending in the longitudinal direction of said. pressure equalising chamber, and said separating tube is connected to said end of said internal connector.

Claims (5)

1. In a diaphragm pump capable of operation either as a pressure pump or a suction pump, said pump including a housing, fluid inlet and outlet means for said housing, and a pumping mechanism including diaphragm means arranged within said housing for pumping a fluid therethrough and drive means for actuating said diaphragm means, the improvement comprising a division wall located interiorly of said housing dividing said housing internally into a pump chamber and a pressure equalization chamber, said housing being structured in a longitudinal configuration with a length dimension greater than the dimensions extending transversely thereof, said partition wall being located to extend longitudinally of said housing, means defining inlet and outlet openings to said pressure equalization chamber, the effective separation between said inlet and said outlet openings being at least half the length of said pressure equalization chamber, a separating tube and means connecting said separating tube to one of said inlet and said outlet openings of said pressure equalization chamber whereby said separating tube extends within said pressure equalization chamber for a sufficient distance to provide said effective separation between said inlet and said outlet openings.

2. A diaphragm pump as in claim 1, including means mounting said pumping mechanism on said division wall forming said pressure equalising chamber, a sealing plate interposed between said pumping mechanism and said division wall, and said pumping mechanism including a valve plate, means locating said valve plate, and plug means retaining said valve plate in location, said plug means being formed integrally with said sealing plate.

3. A diaphragm pump as in claim 1, wherein said means defining said actual inlet and outlet openings of said pressure equalising chamber are situated opposite each other in said longitudinal division wall and the wall of said housing respectively, and said separating tube extends for a distance of at least half the length of said pressure equalising chamber.

4. A diaphragm pump as in claim 3, wherein said separating tube is connected to said outlet opening, and said means connecting said tube to said opening comprises a connecting piece fitted in said opening and having an external connector and an internal connector which communicates with said external connector, and means connecting said separating tube to said internal connector.

5. A diaphragm pump as in claim 4, wherein said internal connector is bent to provide an end extending in the longitudinal direction of said pressure equalising chamber, and said separating tube is connected to said end of said internal connector.

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