US2920573A - Diaphragm feed pump - Google Patents

Description

Jan. 12, 1960 SCHAURTE 2,920,573

DIAPHRAGM FEED PUMP Filed Dec. 19, 1957 United i States Patent O DIAPHRAGM FEED PUMP Paul Schaurte, Vaduz-Bartlegrosch, Liechtenstein Application December 19, 1957, Serial No. 703,840 Claims priority, application Germany December 22, 1956 9 Claims. (Ci. ID3- 44) The present invention relates to a diaphragm feed or vacuum pump, and more particularly to improvements in a pump of a type which has a check valve wlthin the outlet conduit, and which essentially comprises two resilient diaphragms, at least one of which is extensible, and between which an incompressible pressure transmitting iluid is provided. One of these diaphragms is adapted to be moved back and forth at a constant stroke and thus acts through the pressure transmitting uid upon the other diaphragm to compress the latter into an annular recess in a wall of the pump housing. The volume of the chamber enclosed by the two diaphragms and containing the pressure transmitting fluid remains constant during both the compression and suction strokes. The outer surface of the positively reciprocated diaphragm of this type of pump is generally exposed to the normal atmospheric pressure with the result that this diaphragm easily bulges outwardly when the pressure in the pump chamber exceeds a certain value. In other words, if the pump is to operate properly, the pressure of the medium to be conveyed may never exceed such value. A further disadvantage of a pump of this type is that it contains considerable dead space even though the diaphragm covering the pump chamber might fully engage with the opposite walls thereof during the compression stroke. Furthermore, this type of pump required a check valve in both the inlet and outlet conduits thereof.

It is an object of the present invention to provide a diaphragm feed pump of the above-mentioned type which is especially adapted to be used as a vacuum pump, and overcomes all of the above-mentioned disadvantages of similar pumps of previous designs.

For attaining this object the present invention provides a diaphragm pump in which the outer side of the driving diaphragm, that is, the side opposite to the side facing toward the driven diaphragm covering the pump chamber, is maintained under a pressure which is higher than the maximum pressure within the pump chamber, so that this pressure will produce the inward or compression stroke, while the outward or suction stroke will be produced by a driving means through a traction member which is positively connected to the driving diaphragm and may form an integral part of this diaphragm. Particular advantages will also be attained if the outer ends of both diaphragms which enclose the pressure transmitting uid are clamped within the same plane.

Further objects, features, and advantages of the present invention will become apparent from the following detailed description thereof, particularly when read with reference to the accompanying diagrammatic drawing of one preferred embodiment of the invention.

As illustrated in the drawing, a housing 1 contains a shaft 2 which is rotatably mounted in suitable bearings, not shown, and extends through one side wall of housing 1 by being sealed toward the outer atmosphere by suitable packing means, not shown. Shaft 2 carries an eccentric cam 3 which is surrounded by a disk which consists of two parts 4 and 5 between which a resilient member 6 is clamped which is connected to an outer or driving diaphragm 7 or may form an integral unit therewith. Diaphragm 7 is preferably reinforced at its central part by a cup-shaped member 8.

Diaphragm 7 and a second diaphragm 9 are clamped together between the housing parts 1 and 10 by means of bolts 11 and form a chamber 17 which is filled with an incompressible iiuid, for example, oil. Housing part 10 which may form a solid base or cover of the pump contains an inlet conduit 12 at the center thereof. The opening of conduit 12 in the pump chamber 13 may be covered by suitable means, not shown, so as to protect diaphragm 9 from being damaged when it engages with the edge of this opening. This pump chamber 13 is formed by an annular recess in housing part 10` which also has an outlet opening into an outlet conduit 14 in which a check valve is mounted which may consist, for example, of a plate 16 which is acted upon by a spring 15. The outer chamber 18 containing the driving elements may be filled with a gaseous or liquid medium under a pressure higher than the maximum pressure which is to be expected within pump chamber 13. Chamber 18 may also be connected by a conduit 19 to a suitable pump 20 or pressure tank, although a pressure of suicient strength may once be provided in chamber 18 and the same may then be closed.

Since chamber 18 contains a higher pressure than pump chamber 13, the resilient member 6 will only be subjected to traction. When drive shaft 2 rotates, diaphragm 7 can move in the direction toward housing part 10, whereby diaphragm 9 will also move into pump chamber 13 because of the incompressible fluid contained. between the two diaphragms 7 and 9. Diaphragm 9 will then at first engage with and shut oif the mouth of the inlet conduit 12, whereupon the respective medium to be conveyed which is contained in pump chamber` 13 will be pressed by diaphragm 9 through check valve 15, 16' into the outlet conduit. At the further rotation of shaft 2, cam 3 will draw diaphragm 7 through the connecting member 6 back to the starting position and thereby produce an underpressure in pump chamber 13 which sucks a new supply of the medium to be conveyed through intake conduit 12 into the pump chamber, while check valve 15, 16 prevents the medium already within outlet conduit 14 from being sucked back into the pump chamber. This operation is then repeated at every revolution of drive shaft 2.

Although the invention has been illustrated only with reference to a single two-diaphragm pump, it will be evident that several such pumps may be mounted concentrically to drive shaft 2 or that two such pumps may be mounted so that their inlet conduits 12 extend along the same straight line. If two or more pumps are provided and such pump assembly is to be used as a vacuum pump, it will be advisable to connect these pumps in series so as to operate like a multi-stage pump. It two or more pumps according to the invention will be driven by a single drive shaft, the volume of al1 charnbers 18 will remain constant and they will then in effect constitute a single chamber. In this event, chambers 18 may be filled with an incompressible uid which is acted upon by a pump or the like.

Although my invention has been illustrated and described with reference to the preferred embodimentf thereof, I wish to have it understood that it is in no way limited to the details `of such embodiments, but is capable of numerous modifications within the scope of the ap pended claims.

Having thus fully disclosed my invention, what I claim is:

1. In a membrane pump, in combination, a pump -housing; membrane means arranged in said housing subdividing the same into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable'in said housing in a direction away from said pumping chamber toward said pressure chamber and vice versa; inlet and outlet means communicating with said pumping chamber; a compressible uid `under pressure permanently filling said pressure .chamber and permanently tending to move said mem- *brane means in direction toward said pumping chamber, said uid exerting its action upon said memb-rane means substantially over the entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure Which at -all times is higher than the pressure in said :pumping chamber; and means for periodically moving said membrane means in a direction away from said pumping chamber toward said pressure chamber, Whereby during movement of said membrane means the same is permanently supported over substantially the entire surface thereof by said pressure uid in said pressure cham- -ber so as to prevent undesired buckling of said membrane means.

`2. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing sub- `dividing the same into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable in said housing in a direction away from said pumping chamber toward said pressure chamber and vice versa, said membrane means including a flexible pumping membrane facing said pumping charnber and a flexible driving membrane facing said pressure chamber, said membranes being spaced so as to form a pressure-transmitting space therebetween; inlet and outlet means communicating with said pumping chamber; a non-compressible uid filling said pressure-transmitting space; a compressible fluid under pressure permanently vfilling said pressure chamber and permanently tending to move said driving membrane in direction toward said pumping chamber, said fluid exerting its action upon said driving membrane substantially over the entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher than the pressure in said pumping chamber; and means for periodically vmoving said driving membrane in a direction away from Nsaid pumping chamber toward said pressure chamber,

whereby during movement of said driving membrane the same is permanently supported over substantially the entire surface thereof by said pressure fluid in said pressure chamber so as to prevent undesired buckling of said driving membrane.

3. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing subdividing the same into a pumping chamber anda closed ,pressure chamber, said membrane means being deformably alternatively movable in said housing in a direction ,away from said pumping chamber toward said pressure chamber and vice versa; a projection on said pump housing extending into said pumping chamber toward said .membrane means, said projection being formed with an entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher than the pressure in said pumping chamber; and means for periodically moving said membrane means in a direction away from said pumping chamber toward said pressure chamber, whereby during movement of said membrane means the same is permanently supported over substantially the entire surface thereof by said pressure iluid in said pressure chamber so as to prevent undesired buckling of said membrane means.

4. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing subdividing the same into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable in said housing in a direction away from said pumping chamber toward said pressure chamber and vice versa, said membrane means including a Lilexible pumping membrane facing said pumping chamber anda exible driving membrane facing said pressure chamber, said membranes having peripheral portions secured to said housing and central portions spaced apart so as to form a pressure-transmitting space therebetween; inlet and outlet means communicating with said pumping chamber; a non-compressible fluid filling said pressuretransmitting space; a compressible iluid under pressure permanently filling said pressure chamber and permanently tending to move said driving membrane in direction toward said pumping chamber, said Huid exerting its action upon said driving membrane substantially over the entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher than the pressure in `said pumping chamber; and means for periodically moving said driving membrane in a direction away from said pumping chamber toward said pressure chamber, whereby during movement of said driving membrane the same is permanently supported over substantially the entire surface thereof by said pressure fluid in said pressure chamber so as to prevent undesired buckling of said driving membrane.

5. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing subdividing the same into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable in said housing in a direction away from said pumping chamber toward said pressure chamber and vice versa, said membrane means including a flexible pumping membrane facing said pumping chamber and a iiexible driving membrane facing said pressure chamber, said membranes having peripheral portions jointly secured to said housing along a common plane and central portions spaced apart so as to form a pressuretransmitting space therebetween, a non-compressible fluid filling said pressure-transmitting space; inlet and outlet means communicating with said pumping chamber; a compressible fluid under pressure permanently filling said pressure chamber and permanently tending to move said driving membrane in direction toward said pumping lchamber, said fluid exerting its action upon said driving membrane substantially over the entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher than the pressure in said pumping chamber; and means for periodically moving said driving membrane in a direction away from said pumping chamber toward said pressure chamber, whereby during movement of said driving membrane the same is permanently supported over substantially the entire surface thereof by said pressure iluid in said pressure chamber so as to prevent undesired buckling of said driving membrane.

-6. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing submembrane means dividing the same into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable in said housing in a direction away from said pumping chamber-toward said pressure chamber and vice versa; inlet and outlet means communicating with said pumping chamber; a compressible uid under pressure permanently filling said pressure chamber and permanently tending to move said membrane means in direction toward said pumping chamber, said uid exerting its action upon said membrane means substantially over the entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher vthan the pressure in said pumping chamber; a resilient member mounted on said membrane means in said pressure chamber; and means for periodically moving said resilient member in a direction away from said pumping chamber toward said pressure chamber, whereby during movement of said the same is permanently supported over substantially the entire surface thereof by said pressure uid in` said pressure chamber so as to prevent undesired buckling of said membrane means.

7. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing subdividing the lsame into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable in said housing in a direction away from said pumping chamber toward said pressure chamber and vice versa; inlet and outlet means communicating with said pumping chamber; a compressible uid under pressure permanently filling said pressure chamber and permanently tending to move said membrane means in direction toward said pumping chamber, said uid exerting its action upon said membrane means substantially over the entire free surface thereof; a resilient member mounted on said membrane means in said pressure chamber; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher than the pressure in said pumping chamber; and eccentric means rotatable in said pressure chamber for periodically moving said resilient member in a direction away from said pumping chamber toward said pressure chamber, whereby during movement of said membrane means the same is permanently supported over substantially the entire surface thereof by said pressure uid in said pressure chamber so as to prevent undesired buckling of said membrane means.

8. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing subdividing the same into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable in said housing in a direction away from said pumping chamber toward said pressure chamber and vice versa; inlet and outlet means communicating with said pumping chamber; a compressible uid under pressure permanently filling said pressure chamber and permanently tending to move said membrane means in direction toward said pumping cham ber, said iluid exerting its action upon said membrane means substantially over the entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher than the pressure in said pumping chamber; a resilient member integral with a portion of said membrane means in said pressure chamber; and means for periodically moving said resilient member in a direction away from said pumping chamber toward said pressure chamber, whereby during movement of said membrane means the same is permanently supported over substantially the entire surface thereof by said pressure uid in said pressure chamber so as to prevent undesired buckling of said membrane means.

9. In a membrane pump, in combination, a pump housing; membrane means arranged in said housing subdividing the same into a pumping chamber and a closed pressure chamber, said membrane means being deformably alternately movable in said housing in a direction awayA from said pumping chamber toward said pressure chamber and vice versa, said membrane means including a flexible pumping membrane facing said pumping chamber and a flexible drilling membrane facing said pressure chamber, said membranes being spaced so as to form a pressure-transmitting space therebetween; inlet and outlet means communicating with said pumping chamber; a non-compressible uid filling said pressure-transmitting space; a substantially rigid backing member in said pressure-transmitting space for backing contact with said driving membrane; a compressible fluid under pressure permanently filling said pressure chamber and permanently tending to move said driving membrane in direction toward said pumping chamber, said fluid exerting its action upon said driving membrane substantially over the entire free surface thereof; inlet means communicating with said pressure chamber for supplying and maintaining in the latter a pressure which at all times is higher than the pressure in said pumping chamber; and means for periodically moving said backing member in a direction away from said pumping chamber toward said pressure chamber, said backing member contacting said driving membrane and moving the same toward said pressure chamber, whereby during movement of said driving membrane the same is permanently supported over substantially the entire surface thereof by said pressure uid in said pressure chamber so as to prevent undesired buckling of said driving membrane.

References Cited in the le of this patent UNITED STATES PATENTS 1,691,128 Redmond Nov. 13, 1928 2,575,398 Schroeder Nov. 20, 1951 2,700,340 Wood Jan. 25, 1955 FOREIGN PATENTS 305,235 Great Britain Feb. 1, 1929

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