US 3605566 A
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Description (OCR text may contain errors)
Sept. 20, 1911 .Filed Dec. 9, 1968 G. VETTER HYDRAULIC DIAPHRAGM PUMP 2 Sheets-Sheet 1 FIG.1
I/Vl/AWTDR Sam/M1) vErrm Sept. 20, 1971 TT 3,505,555
HYDRAULIC DIAPHRAGM mar Filed Dec. 9. 1968 2 Sheets-Sheet 2 I/vvn/ro/e GEkhW/RD VETTER FWTDRIVE/S United States Patent lfice 3,605,566 HYDRAULIC DIAPHRAGM PUMP Gerhard Vetter, Niefern, Germany, assignor to LEWA Herbert Ott, Leonberg, near Stuttgart, Germany Filed Dec. 9, 1968, Ser. No. 782,172 Claims priority, application France, Dec. 15, 1967, 132,488 Int. Cl. F16j 3/00 U.S. Cl. 92-5 4 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a diaphragm pump, in which the diaphragm consists of at least two individual diaphragms. A space between the two individual diaphragms is completely filled with a hydraulic medium. The space communicates with a hydraulic tank via a conduit containing a non-return valve opening towards the hydraulic tank.
The invention relates, as indicated, to a diaphragm pump with hydraulic displacement drive and with a diaphragm consisting of at least two individual, superimposed, diaphragms.
Diaphragm pumps of this type have been used widely, particularly in the field of chemical engineering. They have been adopted especially for metering, where one diaphragm separates the actual delivery chamber from a Working chamber filled with hydraulic working medium and is actuated by the hydraulic medium displaced by a mechanical piston. However, in pumps with this hydraulic displacement drive, the monitoring of the diaphragm for damage and fractures is difficult, because, when the diaphragm is damaged, the delivery medium and the hydraulic medium may combine; this cannot be immediately detected and can lead, in view of the large quantities of hydraulic or delivery medium, to a substantial contamination of the delivery chamber or of the hydraulic chamber. Particularly with toxic delivery media, the monitoring and safety are of paramount importance. For this reason it has already been proposed, for example in German Pat. 710,310 of Sept. 10, 1941 and U.S. Pat. No. 3,131,638, to arrange, for example, three or more diaphragms in superimposed position, wherein the at least one of the center diaphragm is perforated and provided with slots leading radially outwardly. One or more of these slots communicate with the environment. In the case of fracture of one of the two external diaphragms, which are in contact with the delivery medium and with the hydraulic medium, respectively, the medium penetrating through the fracture flows along the slots in the center diaphragm towards the outside and may there be conducted to a suitable monitoring device. In order to act as a single diaphragm, the three individual diaphragms must be interconnected by gluing. However, this glued joint is subjected to substantial shearing forces, particularly at higher pressures, stresses the diaphragms in a very unfavourable manner during the suction stroke and affects therefore the operational reliability of the whole installation to a marked degree. In addition, it has also been found that, with the initially very fine cracks in the diaphragms, only very little medium flows into the slots of the centre diaphragm, whilst the mechanical operation of the whole arrangement is so affected by these fine cracks that a further diaphragm may fracture before the indication occurs. For this reason it has already been proposed in the German published specification No. 1,226,740, to connect the space between at least two diaphragms to a vacuum vessel with a vacuum meter. However, this arrangement requires, in order to prevent the diaphragms from lifting during the 3,605,566 Patented Sept. 20, 1971 suction stroke, the maintenance of a good vacuum in the vacuum chamber by means of a vacuum pump, and is therefore rather expensive. Since, when the vacuum drops owing to a failure of the vacuum pump, the function of the diaphragm pump is immediately impaired, this installation is not very reliable in operation.
The present invention has therefore the object of proposing a hydraulic diaphragm pump with several diaphragms acting together as a unit, and ensuring a reliable,
uniform, transmission of the pumping forces to the individual diaphragms at low structural expenditure. According to the invention, this object is realized in that the space between the individual diaphragms is completely filled with the hydraulic medium.
Preferably, the space between the individual diaphragms communicates through a lateral connection with a hydraulic tank. Preferably also, an intermediate diaphragm provided with slots is mounted between the working diaphragms. Conveniently, the diaphragms have lateral tongues with connections, and a spring-loaded nonreturn valve is mounted in the connection to the hydraulic tank.
In order to facilitate the assembly of the diaphragms, these are preferably welded or glued together along their edges.
The invention will be further described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 shows a partly diagrammatical cross-section of a diaphragm pump according to the invention, and
FIG. 2 shows a single diaphragm acting as intermediate diaphragm in the hydraulic diaphragm pump.
A diaphragm 3, consisting, as known in the art, of several individual diaphragms 3a, 3b, 3c, is fixed between a cylinder cover 1 and a hydraulic cylinder 2. The inlet and outlet valves 4 and 4' for the delivery medium are located in the cylinder cover 1. The hydraulic cylinder 2 contains a mechanical displacement piston 6 in a hydraulic chamber 7, containing a perforated plate 8, known in the art, against which the diaphragm 3 is supported during the suction stroke to prevent deformation.
The diaphragms 3a, 3b, 3c are superimposed and may be glued or welded together along the edges to facilitate the assembly. As may be seen from FIG. 2, the intermediate diaphragm 31; has a number of radially extending slots, of which one terminates in diametrically opposite lugs 9. The diaphragms 3a and 3c embracing the intermediate diaphragm 3b are tight diaphragms of identical shape. The lateral lugs 9 are equipped with connections 10 and 11. The connection 11 is adapted to be closed. The connection 10 communicates via a slightly spring-loaded non-return valve 12 with a tank 13 containing hydraulic oil.
Prior to the assembly, the space between the diaphragms 3a, 3b and 3c and the non-return valve 12, is filled through the connections 10 and 11 with a suitable hydraulic medium. This is effected conveniently by drawing in fluid through a vacuum pump. Then the connection 11 is closed. The tank 13 remains partially filled so that the diaphragms are perfectly hydraulically connected and cannot lift off during the suction stroke. With the use of a suitable hydraulic medium, the suction capacity of this hydraulic pump is in no way restricted. The non-return valve 12 prevents fiuid from flowing in from the tank 13. If one of the said diaphragms 3a, 3b, 3c is damaged of fractured, either delivery medium or hydraulic medium fiows through the non-return valve 12 into the tank 13, when the delivery pressure is higher than the bias of the spring. The fracture of the diaphragm can then by indicated by devices known in the art (e.g., capacitively, inductively or by radioactivity.
The intermediate diaphragm 3b can be omitted and be replaced by an intermediate annulus connecting the outer edges of the two other diaphragms 3a and 30. In order to achieve a selective indication of diaphragm fracture, it is also possible to use a five-member diaphragm as known per se, in which permeable diaphragms, e.g., according to FIG. 2, are arranged between the outer and center tight diaphragms.
By means of the proposed arrangement, the diaphragms are connected in a perfect manner hydraulical ly and loaded at optimum both during the suction and during the delivery strokes. Since the reliable maintenance of this hydraulic coupling requires only the provision of the tank 13, filled with hydraulic fluid, the structural expenditure is reduced to a minimum. Functionally the diaphragms form a closed unit, whilst enabling the perfect monitoring of diaphragm fractures to be carried out. If a fracture occurs of the diaphragm in contact with the delivery medium, only a very small amount of hydraulic fluid enters the delivery chamber, owing to the smallness of the chamber 5 between the diaphragms.
1. A diaphragm pump comprising a first variable volume pump chamber communicating with a hydraulic displacement drive means and a second variable volume pump chamber for the medium to be delivered, a diaphragm means separating said first and second cham-' bers, said diaphragm means comprising at least two individual diaphragms which are hydraulically connected by a hydraulic fluid completely filling an intermediate space between the two individual diaphragms, a reservoir containing hydraulic fluid and a biased one-way valve, whereby the intermediate space completely filled with hydraulic fluid is connected to said reservoir 4- through said biased one-way valve and said valve opens in the direction of said reservoir.
2. A diaphragm pump as set forth in claim 1, comprising an intermediate partition arranged between the two individual diaphragms and provided with slots.
3. A diaphragm pump as set forth in claim 1, wherein the individual diaphragms have lateral lugs with connections.
4. A diaphragm pump as set forth of claim 3, wherein two lateral lugs are each provided with a connection, wherein one said connection communicates with the said reservoir containing hydraulic fluid and the other connection communicates with a conduit equipped with closing means.
References Cited UNITED STATES PATENTS 1,421,381 7/1922 Bawtree 92-97X 2,619,777 12/1952 La Point 9297X 2,693,827 11/1954 Bailey 9249X 2,906,095 9/1959 Whitehead 92-49 3,067,944 12/ 1962' Meier 92103 3,131,638 5/1964 Wilson et a]. 103-150X 3,263,618 8/1966 Carpenter 1031-X 3,362,346 1/1968 Bottoms et a1. 103150X 3,410,263 11/1968 McGinnis 103150X MARTIN P. SCHWADRON, Primary Examiner R. H. LAZARUS, Assistant Examiner US. Cl. X.R.