US3508845A - Method of obtaining higher pressures with a diaphragm compressor and diaphragm compressor for carrying out said method - Google Patents

Description

2 Sheets-Sheet 1 F. sTRAssBURGER CARRYING OUT SAID METHOD April 2s, 1970 METHOD OF OBTAINING HIGHER PRESSURES WITH A DIAPHRAGM COMPRESSOR AND DIAPHRAGM COMPRESSOR FOR Filed June 13, 1968 Apnl 2.8, 1970 F. srRAssBURGER 3,508,845

METHOD OF OBTAINING HIGHER PRESSURES WITH A DIAPHRAGM COMPRESSOR AND DIAPHRAGM COMPRESSR FOR CARRYING OUT SAID METHOD Filed June 13, 1968 2 Sheets-Sheet 2 United States Patent C) 3,508,845 METHOD OF OBTAINING HIGHER PRESSURES WITH A DIAPHRAGM COMPRESSOR AND DIAPHRAGM COMPRESSOR FOR CARRYING OUT SAID METHOD Friedhelm Strassburger, Mulheim, Germany, asslguor to Andreas Hofer Hochdruck-Apparatebau G.m.b.H., Mulheim (Ruhr), Germany Filed June 13, 1968, Ser. No. 736,663 Claims priority, application Germany, .lune 14, 1967, H 62,999 Int. Cl. F04b 39/06, 45/00; F15b 7/00 U.S. Cl. 417-32 8 Claims ABSTRACT OF THE DISCLOSURE A high pressure diaphragm compressor in which the cylinder with the reciprocable actuating plunger is heated, and in which heated up oil is pumped by said plunger to the diaphragm of said diaphragm compressor.

The present invention relates to a method of obtaining higher pressures with a diaphragm compressor and also concerns a diaphragm compressor for carrying out said method.

Diaphragm compressors for compressing gases are employed particularly in instances where it is important to protect the gas to be compressed against soiling by lubricants.

The fundamental elements of a diaphragm compressor comprise the hydraulic system and the gas section. These two parts are separated from each other by a suitable diaphragm. The gas part has a cover in which there is provided a suction and a pressure valve through which the gas flows during the compression action. The cover forms the confining surface of the chamber located on the gas side above the diaphragm. At the hydraulic side the diaphragm rests upon a plate provided with thin bores, and the bores establish connection between the chamber on the hydraulic side of the diaphragm and the chamber above the hydraulic piston in the hydraulic cylinder. The reciprocatory movement of the hydraulic piston is transferred to the hydraulic oil and from there to the diaphragm which now, due to its oscillating movement is adapted to draw in gas and compress the same. Diaphragm compressors of this design and operation are known.

With auxiliary compressors working with high end pressures and thus with relatively high intake pressures, the diaphragm breaks relatively easily, and this failure is seen in the bores of the plate in connection with the very high gas intake pressures. While it is possible to dimension the bores theoretically so small that the danger of breakage for the diaphragms is eliminated to a major extent, such a design, however, has the drawback that the compression end pressure cannot be selected as high as desired. In this connection it has been found that the hydraulic oil at high pressure becomes rather viscous and thick. Inasmuch as this viscous mass will, in the narrow bores of the plate, produce a very high pressure head, pressure peeks occur which lead to the destruction of the plate and of the hydraulic cylinder. The limit of the maximum obtainable compression end pressure is determined by the size of the bores in the plate and, more specifically, by such free inner diameter of the bores which offers too high a resistance against the viscous hydraulic oil under high pressure. On the other hand, the bores must be relatively small because otherwise the diaphragm would be destroyed under the inuence of the high gas intake pressure.

It is an object of the present invention to provide a method and device which on one hand will permit further Patented Apr. 28, 1970 to increase the gas end pressure while on the other hand will relieve the plate and the hydraulic cylinder from dangerous high pressure heads.

These objects and other objects and advantages of the invention will appear more clearly from the following specification, in connection With the accompanying drawings, in which:

FIGURE 1 is a diagrammatic illustration and shows a vertical cross section through a diaphragm compressor with a container for the hydraulic oil and with inlet and outlet conduits.

FIGURE 2 shows an electric circuit for preventing operation of the compressor when the temperature of the operating oil is insuicient.

The method according to the present invention is characterized primarily in that the hydraulic cylinder and the parts adjacent thereto are preheated and that warm oil is employed as operating uid. These steps bring about that also at high pressures, the liquid character of the oil remains maintained and that no inadmissible or dangerous pressure heads can occur in the bores of the plate. This has the advantage that not only will there be obtainable very high gas pressures, but also breakage of the diaphragm will for all practical purposes be excluded.

According to a preferred method of the present invention, the warm oil serving as operating liquid is also simultaneously employed for heating the hydraulic cylinder. This results in a simplied circuit for the liquids, and it is not necessary to keep available two diierent liquids.

A diaphragm compressor for carrying out the above mentioned method is, according to the present invention, characterized in that the hydraulic cylinder within the range of the piston has a double mantle or double wall, the inner chamber of which through inlet and outlet conduits with interposed circulating pump is connected to a container or tank with a heating means for hydraulic oil. The diaphragm compressor according to the present invention is furthermore characterized in that the inner chamber of said container is through additional inlet and outlet conduits by means of an interposed high pressure pump connected to the interior of the hydraulic cylinder at the head side of the piston.

This design permits an easy heating up of the compressor body and also a simple way of placing the conduits for the operating liquid.

According to a preferred embodiment of the invention, a pressure limiting valve may be arranged in the outlet conduit for the operating liquid. In this way the desired pressure can be precisely maintained.

According to a further `development of the present invention, a contact thermometer may be placed in the ow path of the hydraulic oil, which thermometer at a predetermined minimum temperature which is expedient for obtaining the desired effect, acts upon an electric relay, which in its turn closes a contact and thereby an electric circuit for initiating operation of the driving motor for the diaphragm compressor. Thus, the motor is started only and remains in operation only when the hydraulic cylinder has the said minimum temperature. In this way, also during the starting phase care will be taken that the diaphragm will not break, in view of too high pressure head in the bores of the plate below the diaphragm. Corresponding remarks also apply to the period during operation.

According to a still further development of the invention, in the electric circuit for initiating operation of the driving motor there is'provded a relay with closing contact, which relay is in series with an overload safety switch acting upon a breaker switch. This relay responds to the actuation of a switch for starting the circulating pump so that the motor can start and remain in operation only when the circulating pump feeds. As a result thereof, a

second safety feature is obtained in view of which the compressor, in case of a failure of the circulating pump and the probability inherent thereto that the temperature of the hydraulic oil drops will be turned off automatically.

Referring now to the drawings in detail, the diaphragm compressor shown therein comprises a cover 1 arranged on the gas side and provided with a suction valve and a pressure valve for the gas to be compressed. The compressor furthermore comprise-s a diaphragm 2 at the bottom side of the cover 1, and also comprises a plate 3 with fine bores 4, said plate being arranged on 4the bottom side of the diaphragm 2. The compressor also includes a hydr-aulic cylinder 5 carrying the plate 3 and the cover 1 and having a plunger 6 reciprocally arranged therein and surrounded by a seal 7. At a suitable place of the machine there is provided a container or tank -8 for the hydraulic oil which within the tank has a heating device 9, for instance, an electric resistance heater with temperature control, for heating up the tank and the contents thereof. The hot oil is, by means of a circulating pump 10 delivered through a feeding conduit 8a into the interior chamber 5a of a double mantle or double walled part in the central area of the hydraulic cylinder v5 where it heats up the hydraulic cylinder and the parts adjacent thereto. The oil which has given olf its heat content leaves the chamber 5a through a discharge conduit 8b and returns to the tank 8.

A high pressure pump 11 which is driven by a motor 13 (indicated in FIG. 2 only) through the intervention of a transmission of any standard type, for instance, a crank drive (not shown), delivers the hot hydraulic oil from the tank 8 through a feeding line 8c into the space above the plunger 6 into the hydraulic cylinder S. From here the liquid passes through bores 4 in plate 3 below the diaphragm 2. -In View of this post-feeding of operating liquid through conduits 8c, also losses will be compensated for which might have by-passed the seal 7. The hydraulic oil excessively introduced into the cylinder chamber passes through a pressure limiting valve 12 or check valve and a return conduit y8d back to the oil tank 8.

The preheated machine and the preheated hydraulic oil bring about that the hydraulic oil will also at high pressure remain liquid and that, therefore, too high pressure heads cannot occur in the bores 4.

FIG. 2 illustrate-s an electric circuit which is adapted to exclude damages to the compressor as a result of improper operation. The circuit shows the circulating pump 10 with the driving motor 10a pertaining thereto, the driving motor 13 for the diaphragm compressor, a relay 14 for turning on and turning off the compressor motor, and a relay 15 for actuating the motor of the circulating pump 10. The relay 15 comprises a closing contact 15a which is shown in the lower part of FIG. 2. A Contact thermometer 16 which is arranged at a suitable pl-ace within the circuit of the operating liquid is connected to a relay 17 by the closing switch 15a. Two switches 18 `and 19 and an overload safety device 20 on the circulating pump 10 and an opening Contact 20a complete the circuit.

The purpose of the circuit consists in permitting the star-ting of the driving motor 13 for the diaphragm compressor only when the machine has reached a minimum temperature which latter is measured and indicated by the contact thermometer 16. As soon `as the minimum temperature lhas been obtained, the relay 17 is switched on and closes the contact 17a. The compressor could now be started through the switch 18, however, a second safety feature is provided, namely, the relay 15 with the contact switch 15a. This second safety feature brings about that the machine can run only when the circulating pump 10 is in operation, in other words When the relay 15 is attracted by the switch 19. It it should occur that the motor of the circulating pump 10, due to an overload, is switched off by means of the fuse or overloading safety device 20 and the opening switch 20a pertaining thereto, the relay 15 will open and also the rel-ay 14 pertaining to the compressor motor 13 because the switch 15a opens and the driving motor 13 stops.

Thus, a turning on of the motor 13 is possible only when the minimum temperature of the hydraulic oil or of the machine has been obtained and when the circulating pump is in operation. If, however, the temperature of the oil and of the machine drops during operation below the adjusted minimum value, relay 17 becomes operative, opens switch 17a, and brings about that the relay 14 in view of the opening switch 17a and consequently also the driving motor 13 for the compressor will be switched olf.

It is, of course, to be understood that the present invention is, by no means, limited to the particular structural arrangement and circuit shown in the drawings, but also comprises various mod'itications within the scope of the invention.

What is claimed is:

1. A method of creating high pressures in a diaphragm compressor having a hydraulic cylinder with a plunger therein at indispensable high temperature level, which includes the steps of: preheating directly said hydraulic cylinder and adjacent parts thereof, and feeding directly preliminarly headed up operating oil to said plunger to be pumped by the latter to the diaphragm of said compressor for steady heat interchange directly therewith` 2. A method according to claim 1, which includes the step of: employing a portion of the preliminarily heated up oil directly for uniformly pre-heating said hydraulic cylinder from inside and from outside thereof simultaneously maintained at the same temperature by utilization of the preliminarily heated up oil directly as the same f eating medium.

3. A diaphragm compressor which includes: a cylinder jacket means surrounding said cylinder and defining chamber means therewith, plunger means reciprocable in said cylinder and having a pressure exerting end, pumping diaphragm means having one side thereof in fluid communication with said pressure exerting end and having its opposite side arranged for communication with a gas to be compressed, fluid reservoir means, heating means associated with said fluid reservoir means for heating uid therein, rst conduit means including high pressure pump means for establishing fluid communication between said reservoir means and said pressure eX- erting end of said plunger means and conveying heated up actuating tiuid thereto, and second conduit means including fluid circulating pump means for establishing lluid communication between said reservoir means and said chamber means and conveying heated up uid to said chamber means for heating up said cylinder.

4. A compressor according to claim 3, in which said rst conduit means includes a return conduit communieating with said pressure exerting end and leading yback to said reservoir means, and check valve means interposed in said return conduit.

5. A compressor according to claim 3, which includes: electric motor means drivingly connected to said plunger means for actuating the same, and adjustable temperature responsive second conduit means for measuring the temperature of the uid passed therethrough to said cylinder, said temperature responsive means being electrically connected to said motor means to prevent operation thereof when the temperature measured by said temperature responsive means is below the temperature for which said temperature responsive means has been set.

6. A compressor according to claim 5, which includes: electric circuit means comprising an exciter circuit for said motor means, relay means, and switch means controlling said exciter circuit and adapted to be closed by said relay means in response to the energization of the latter to thereby close said exciter circuit and permit op- 5 eration of said motor means, said temperature responsive means including switch means operable to close said circuit means for energization of said relay in response to said temperature responsive means measuring a ternperature at least equal to the temperature for which said temperature responsive means has been set.

7. A compressor according to claim 6, which includes: additional motor means drivingly connected to said uid circulating pump means, additional relay means, a control switch controlling said exciter circuit and adapted to be closed by said additional relay means in response to the energization of the lattter, and a manually operable control switch associated with said circulating pump means for closing the circuit thereof, said manually operable control switch being located in said circuit means and operable when closed to energize said additional relay means whereby said motor means can actuate said plunger means only when both said circulating pump means and said high pressure pump means are in operation.

References Cited UNITED STATES PATENTS 1,769,044 7/1930 Stevens 103-44 2,085,286 6/1937 Abercrombie 103-44 2,092,629 9/1937 Allen 103-44 ROBERT M. WALKER, Primary Examiner U.S. Cl. X.R.

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