US2890810A - Exhaust-pump-provided lid for a vacuum container - Google Patents

Description

June 16, 1959 G, ROHLlNG 2,890,810

Filed Marchv 15, 1955 EXHAUST-PUMP-PROVIDED LID-FOR A VACUUM CONTAINER 2 Sheets-Sheet 1 INVENTCR `GISELA ROHLING ATTORNEY June 16, 1959 G. ROHLING EXHAUST-PUMP-PROVIDED LID-FOR A VACUUM CONTAINER Filed March 15, 1955 2 Sheets-Sheet 2 4 I l I lNvENToR GSELA ROHLING ATTORNEY United States EXHAUST-PUMP-PROVIDED LID FOR A VACUUM CONTANER Gisela Rohling, Oberdorf, near Immenstadt, Allgau, Germany The present invention relates to a vacuum container.

It is known to use evacuated containers for various articles, such as food materials, beverages, and the like, in order to keep the said materials fresh for some time. Apart from the old method of evacuating lglass jars iilled with the articles, by evacuating a larger vessel accommodating the jars, it has been proposed to provide on the lid of the jar a manually operated membrane-or piston pump. In these known vacuum jars the pump, or at least its operating member, projects above the cover of the jar, whereby it is impossible to pile up the jars. Also it is impossible to estimate the pressure in the jar. Owing to the clearance space in the interior of the pump only a somewhat reduced air pressure could be produced within these containers, so that in most instances even special clips were required in order to hold the cover on the evacuated container.

It is one object of the present invention to provide a lid or a cover for a vacuum container avoiding these drawbacks.

It is another object of the present invention to provide in a lid or cover for a vacuum container a diaphragm or membrane pump which is attached to the upper rim of the container, with an interposed packing ring, said pump having a hand-operated piston and being disposed above a pump chamber having the shape of a truncated cone and tted with a suction valve in its bottom Wall, and an exhaust valve in the piston, and, if desired, With an air admission valve, which pump is completely received by said lid or cover at the lower end of its downward stroke.

It is yet another object of the present invention to provide in a lid or cover for a vacuum container a diaphragm or membrane pump, the piston of which is formed with a ilat surface and is guided in a bore of the top wall of the chamber dened in ysaid lid the diameter of said chamber corresponding substantially to the cross section of the piston, while its underside has a truncated cone shape conforming to the bottom wall of the piston. This offers the advantage that Vthe piston which is at on its surface and of a considerable width, in its depressed position lies flush with the top wall of the lid, whereby in turn it is possible to pile up several vacuum containers of this kind. Moreover, it is much easier to depress a piston which is flat on its surface than a narrow oblong member. Owing to the shape of the piston adapted to the lower side of the pumping space the clearance is reduced to such an extent that eicient working is possible.

It is also another object of the present invention to provide in a lid or cover for a vacuum container a pump, the piston of which may consist of a cylindrical top part and a truncated-cone-shaped lower part, the annular dia- ICC phragm or membrane being clamped between thesetwo parts. Advantageously an exhaust valve may be arranged within the lower part ofthe piston in such a way that an annular gap is formed between the nipple ofsaid valve and the bore of the piston, for accommodation of a return spring. Similarly, the `stem of the suction valve a1- ranged on the bottom Wall of the chamber may project into a cylindrical bore of the piston, defining an annular gap foraccommodation of the return spring. A cover ring gripping the outer margin of the membrane may be provided for securing the membrane on the cover of the container and guiding the piston.

A return spring may be provided for assisting the return motion of the membrane with the piston. Advantageously, the sum of its spring force and the spring action of the membrane is adapted in such a way that it would no longer be sufficient to return the piston into its initial position as soon as the vacuum required for preserving the content of the container has been attained. In this case, the fact that the piston after a certain number of working strokes does no longer return to its initial position, simultaneously indicates that the required evacuation has been attained. On the other hand, if in the course of the storing of the container the knob should return to its initial position, this would indicate that the vacuum has been decreased and must be restored by renewed operation of the membrane pump.

ln order to prevent impurities, such as, dust from entering into the pump from the interior of the container, a cover plate may be provided below the suction nozzle, and formed with a laterally directed inlet slot into which a ltering material, such as blotting or iilter papermay be inserted.

AIt is a still further object of the present invention to provide in a lid or cover for a vacuum container a'hand pump which may consistof a diaphragm or membrane having two or more fixing bulges and, at its center a tube-shaped projection, a valve chamber being formed inthe center of the membrane by a piston plate and the operating knob, a return spring in the form of a spiral spring which can be depressed in a plane, and a covering ring for holding the membrane and the pump casing together. The arrangement of these parts oifers the advantage that the stroke of the pump can be greatly reduced compared with `the stroke in the existing devices. Moreover, the membrane is reliably secured in its bearings and adapted to take considerable tension forces without injury or leakage of the pump.

It is particularly advantageous if the membrane of the hand-operated pump is provided with a fixing bead or bulge at its outer circumference and with at least one further fixing bead approximately in its innermost-third. By means of this outer fixing bead the membrane maybe tightly clamped outside of an annular projection ofthe casing between the covering ring and the container, so as to exclude the atmospheric air. 'With its inner iixing bead the membrane preferably may be inserted in a recess of thel piston plate and held in its correct position by an annular projection of the operating knob. This modication of the membrane oiers the important advantage that the pump strokey may be made much larger than in any other arrangement without any danger of the membrane being'drawn out of its position between the covering ring and the casing and out of its position between the piston plate and the operating knob. By an increased strokeot 3 the pump in turn it is possible to convey a larger amount of air per stroke, so that the container can be evacuated with less strokes.

It is yet a further object of the present invention to provide a lid or cover for a vacuum container which includes a membrane which may be inserted in the piston plate with two or more inner xing beads and held in its correct position by two or more annular projections of the operating knob. This veryeliable method of securing the membrane between the pistonplate and the operating knob renders it possible to operate even larger membranes than hitherto with such a large stroke that the membrane has to expand considerably when depressing it into the pump space. In this case, the return force of the memfbrane may become so large that the spiral spring can be omitted. The omission of the spiral spring offers the further advantage that the clearance below the pump is further decreased, the construction of the pump is simplilied and possible disturbances by the spring are avoided.

It is also a further object of the present invention to provide a lid or cover for a vacuum container in which the discharge valve may be arranged in such a way that the piston plate carries a cylindrical central stem by which it is linserted in a corresponding recess of the operating knob and over which the tubular central projection of the membrane is drawn. The piston plate moreover may advantageously have an eccentric bore extending in the form of a lateral recess of the central stem up to about one third of its length. Moreover, the inner annular projection or projections of the operating knob may be formed with one or more vent slots. Further vent slots may be arranged at the lower part of the outer wall of the operating knob. This type of arrangement of the valve offers the advantage that it requires only very little clearance. Moreover, the seat of the rubber tube of the air valve connected to the membrane is very reliable, much more so than in case of a plate valve.

It is yet an object of the present invention to providea lid or cover for a vacuum container in which the entire pump except for the operating knob may be covered by the covering ring and the operating knob may project from the covering ring in its position of rest and lie flush with the covering ring in its completely depressed position, in which the spiral spring is compressed into a plane and the membrane and the piston plate are located on the wall of the pump facing them.

It is still another object of the present invention to provide a lid or cover for a vacuum container in which the cover ring merely covers the outer bead of the membrane and the annular projection of the jar or casing, while exposing, in addition to the operating knob, also the upper side of the membrane. In this embodiment the operating knob in addition to its smooth surface is advantageously provided with a handle for exerting a pulling action. In this form the device is adapted to be operated both by drawing and pressing, whereby the stroke of the pump is doubled. Moreover, it is possible to produce a vacuum which is higher than that attainable with pressing alone. No spiral spring is required for returning the operating knob.

In order to facilitate the opening of the evacuated container, a vent valve may be provided on the upper side of the cover. Preferably an air inlet valve is used in which a thimble-shaped rubber tube of soft caoutchouc closed at one end is drawn over a valve nipple and provided with an opening lug. This air inlet valve offers the advantage that the automatic closing of the valve is ensured with a very simple and compact structure. Since the valve is always closed in its position of rest, there is no `necessity of ascertaining before the attaching of the lid whether the valve has been properly inserted. Therefore, the seat of the rubber tube on the valve Inipple is absolutely safe and the packing difficulties occurring with most of the air inlet valves of another construction are avoided. According to a preferred embodiment the rub- '(5 ber tube for the valve may be provided with an annular reinforcement at its open end where the opening lug is provided. By this reinforcing ring the rubber tube is prevented from being torn open in a longitudinal direction by excessive pull on its opening lug.

In order to exclude outer inuences, the valve advantageously may be surrounded by a protective cap from which the opening lug projects and which is provided With an opening for the admission of air.

However, another embodiment would also be possible in which the rubber tube is open at both ends, provided with a reinforcing ring at each end and airtightly secured on the valve nipple at its end opposed to the opening lug, by means of a clip or the like.

Hitherto, rings of caoutchouc or the like are known for sealing the edge or margin with which the cover of the container engages the smooth edge of the lower part of the container. Such rings, however, have the drawback of requiring high packing pressure and large packing surfaces for ensuring a satisfactory seal. Fatty packing agents, such as vacuum fat or the like do not come into question, since they are applicable only in case of ground surfaces accurately fitting on each other, and moreover, they leave residues on the cover or on the edge of the container.

These drawbacks according to the invention are avoided by a packing ring which may he provided in its interior with one or more annular expansion chambers and with one or more packing anges.

It is likewise an object of the present invention to provide a lid or cover for a vacuum container in which the annular part of the packing ring, in whose interior the expansion chamber is disposed, is provided to be inserted in a corresponding annular groove of the lid, while the packing flange engages the edge or rim of the lower part of the container. Moreover, the expansion chamber may consist of an annular air cushion within the packing ring. This packing ring offers the advantage that it can easily adapt itself to any surface. Moreover, when evacuating the vacuum space the expansion chamber will expand to such an extent thatit forces the outer surface of the ring into the corresponding groove, so that the effective sealing surface is substantially increased.

For special purposes the packing ring may have an annular extension on each side for engagement into dove-tailed grooves provided in the lid and in the container. In this way the mechanical adhesion of the lid on the container is ensured and at the same time the packing surface is substantially increased.

With these and other objects in view which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawings, in which:

Figure l is an axial section through the upper part of a vacuum container having the novel lid applied thereto, with the pump in its initial position;

Fig. 2 is a similar section, but showing the lid with tensioned membrane,

Fig. 3 is a fragmentary axial section of a modification of the joint between the container and the lid;

Fig. 4 is an axial section of a modified form of the lid with a hand-operated pump;

Fig. 5 is an axial section of a modified form of a membrane of another form of a hand-operated pump;

Fig. 6 is a fragmentary axial section showing the manner of connecting the membrane disclosed in Fig. 5, with the operating knob completely depressed;

Fig. 7 is an axial section showing still another embodiment of a lid with a hand-operated pump;

Fig. 8 is a sectional view of an air inlet valve provided on the lid ofthe vacuum container; and

Figs. 9 and l0 are fragmentary sectional views showing two improved embodiments of the packing ring for the vacuum container,

Referring now to the drawings in greater detail, and first to Figs. 1 and 2, it be seen that the container 1 is formed ywith a anged rim 2 on which a rubber ring 3 is placed. This ring 3 in its turn is engaged by a correspondingly shaped rim 5 of the lid 4. The central part of the lid is downwardly curved to form a casing 6in the bottomwall of which is provided a cylindrical nozzle or aperture 7 which is covered by a valve plate 8, of rubber or the like. Attached to the rubber disc 8 is a supporting plate 9 having at its underside one or more grooves k10 for the passage of air. Airtightly mounted on the edge of the casing 6, for instance by an adhesive, is a rubber membrane or diaphragm 11. Where the cover 4 consists of a synthetic material, such as polystyrene, the cementing may be effected by means of benzene. The inner edge of the membrane 11 is secured on a ring member 12 in the same way. A complementary ring 13 acting as a piston and also cemented to the membrane engages over this ring 12. Carried by the rings 12 and 13 is a discharge valve body 14 the bore 15 of which is covered by a rubber disc 16. A further ring 17 closes the casing 6 at its top and serves as a guide for the annular piston 13. A cap 18 secured on the piston 13 serves as protection means for the discharge valve body 14 and has a vent slot y19. Inserted between the ring 9 and the valve body 14 is a spiral spring 20. The lid moreover has at its side an air inlet valve, consisting of a bore 21, a rubber tongue 22, and a holding plate 23.

The device operates as follows:

The lid 4 is attached to the container 1 in the manner shown in Fig. l, and by depressing the piston 13 by means of digital pressure applied on the cap 18 the pump is moved into the position shown in Fig. 2, allowing the air in the space of casing 6 below the membrane 11 to escape through the bore 15 and'slot 19. If the nger is lifted, the pump will return into the position shown in Fig. 1 by operation of the spring 20, and the casing 6 will be filled with air entering from the interior of the container 1, through the bore 7 and slot 10. In general, a few strokes of the pump will be sufficient Vto produce the required vacuum. This is indicated by the fact that the piston. 13 even after the lifting of the finger remains in the position of Fig. 2, which statusy is reached when the combined force of the spring 20 with the inner pressure in the container is smaller than that exerted by the atmospheric pressure. If desired, the outer surface of the piston 13 may be provided with a mark catching the eye, eg., a red paint, so as to indicate if the piston 13 again returns to the position of Fig. l owing to insuflcient vacuum.

A protective disc 24with a lateral slot 25 arranged below the casing 6 prevents the penetration of parts ofthe contents of the container 1 into the bore 7. If desired, a sheet of ltering paper may be inserted in the slot 25.

The lid shown in Fig. 3 differs from the embodiment hereinbefore described merely by the fact thatithe rim 51 of the lid 41 is formed with an annular groove in which a packing ring 26 of rubber or the like is xedly embedded. A lid constructed in this way may be put on various containers, e.g., a can 27, after the sheet metal cover has been cut out. In this manner it is possible to provide again an airtight seal on a larger can, containing for instance, marinades, on removal of a part of its contents, in a retail shop or in the household. The remaining parts as the casing 61, the ring 131 and the valve plate 241 are the same as disclosed in the embodiment of Fig. 1.

Fig. 4 shows another embodiment of the lid having 1 a hand pump. In this case the membrane 112 closing the top side of the pump chamber 28,` is provided with two annular beads 29 and30 and made of caoutchouc or the like. The outer fixing lbead 29 acts as a reinforcing ring of approximately circular cross section eX- i is provided on the under side of the membrane. A further portion of the membrane forming a central tube 31 extends from the under side of the internal fixing bead 30. By its outer fixing bead 29 the membrane 112 is clamped between the lid 42 and the covering ring 172 by engaging with -its fixing bead 29 over an annular projection 32 of the casing, so as to form an air-tight seal. Preferably, the covering ring 172 is a solid ring and the nose 33 is formed after its insertion, by thermal deformation. At its inner wall the covering ring forms an abutment 34 for the operating knob 182, which is placed in the central part of the membrane 112 together with the pistonplate 122 which in turn its into the lower truncated cone part of the casing 62 and is urged into its top position by a spiral spring 202 adapted to be compressed into a plane 35. The plate 122 is recessed in such a way that the inner xing bead 30 of the membrane 112 can be inserted into it. The central stud 36 on plate 122 serves as a connecting piece to the operating knob 182 and as a carrier for the valve and engages in a complementary recess 37 of the knob 182. At the side of the central stud 36 the plate 122 is formed with an eccentric bore 38 extending inthe form of a lateral recess up to about one third of the length of the central stud or nipple 36. The tubular portion 31 of the membrane 112 is slipped over the vnipple 36, thus forming an exhaust valve for the air. The lower part of the outer wall of the operating knob 182 engages the membrane 112 and is formed into a flange 4t) which together with the covering ring 172 denes the limit of upward motion of the operating knob 182 and of the membrane 112 with its piston plate 122. The knob 182 is also formed with an inner collar 41 by which the internal tixing bead 30 of the membrane 112 is held in the interior of the plate 122. The annular projection or'collar 41 is formed with one or more slots 42, and the flange 40 is formed with one or more slots 43 permitting the air to escape from the valve chamber in the interior of the knob 182. Provided in the lower part of the truncated cone-shaped pumpY casing 62 is a plate valve 82 of caoutchouc or the like which is held in its position by the plate 92. All parts of the pump except for the spring 202, the membrane 112 and the plate valve 82 are advantageously made of a synthetic material, such as polystyrene. The piston plate 122 and the operating knob 182 or its annular projection 41 are cemented with the membrane 112 or the bead 30 in a suitable manner.

For evacuating the vacuum container the operating knob 18 of the pump may be depressed repeatedly until it does no longer return to the outside. When depressing the operating knob 182 the membrane 112 and the piston plate 122 are forced inwards until they engage the inner wall of the casing 62 and the spiral spring 202 is in the plane 35. Hereat, the interior space 28 of the pump is greatly diminished and the air therein is compressed, whereby the valve 82 is pressed onto its seat, into its closed position. As soon as the overpressure in the interior space 28 of the pump has reached a certain amount, the rubber tube 31 of the membrane 112 is lifted from its seat on theA central nipple 36 of the piston plate 122. The air escapes through the rubber tube 31 and the slots 42 and 43 of the annular projection 41 and of the ange 40 of the operating knob 182, respectively. As the operating knob 182 is let go, the membrane 112, the piston plate 122 and the operating knob 182 are returned to their original position by the elasticity of the membrane and the effect of the spring 202, until the flange 40 engages the abutment 34 of the covering ring 172. The interior space or chamber 28 of the pump is again substantially enlarged and the remaining air is thus diluted. v The valve 82 is lifted from its seat and air is sucked off from the container until the balance of pressure has been established. This pumping process is repeated until the elasticity of the membrane and the force of the spring 20 are no longer sufficient to permit the operating knob 182 to project from the covering ring 172 against the atmospheric pressure acting on the membrane 112. The vacuum thus attained depends on the strength of the spring 202 but is preferably chosen so that a residual air pressure of 300 to 400 Torr. is attainable in the interior of the vacuum container.

A further embodiment of the hand pump is shown in Figs. and 6. In this case the membrane 113 is made larger than in the examples of Figs. 1 to 4. Again it is formed with an outer fixing bead 293. However, in its central part it has two further xing beads 393 an 443 which are both annular and of a rectangular cross section. The central fixing bead 303 is situated approximately in the center of the membrane 113, while the innermost fixing bead 443 is in the innermost quarter of the membrane 113 and on its top side. Within the fixing bead 443 the membrane 113, the same as that according to Fig. 4, is formed with a rubber tube 313. Above the membrane 113 there is again the operating knob 183 and below the same, the piston plate 123, the membrane 113 being sandwiched therebetween in such a way that an annular portion 45 of `the membrane is freely movable. In Fig. 6 the membrane 113 with its adjacent parts is shown in a fully depressed condition of the operating knob 183. Here again the outer fixing bead 293 of the membrane is sandwiched between thecasing 63 and the covering ring 173, the airtight seal being ensured by the projection 323 which in this case is formed somewhat larger than in the example as per Fig. 4. The piston plate 123 and the operating knob 183 are. also larger, but shaped substantially in the same way as in Fig. 4. The operating knob 183 has two internal annular Vprojections 413 and 463, the outer one, 413, engaging the fixing bead 30 of the membrane 113, the same as in Fig. 4. The inner annular projection 46 engages the fixing bead 443 and at the same time presses the membrane 113 onto the inner surface of the piston plate 123. As will be seen from Fig. 6, the freely movable ring 45 of the rnembrane 113 is strongly stretched by depression of the operating knob 183, to the width 45. The elastic return forces thereby produced are so considerable that a return spring can be dispensed with. The cone angle 47 of the pumping chamber in this embodiment is smaller than in the example of Fig. 4. Owing to the fact that the membrane is xed by means of its fixing beads 293, 30 and 443, it is possible to diminish the cone angle and thus to increase the stroke volume of the pump without enlarging the diameter of the membrane.

The operation of the hand pump as per Figs. 5 and 6 is the same as that as per Fig. 4 except that the return force is produced by the membrane 113 itself.

A further modification of the invention is shown in Fig. 7. The membrane is the same as in Fig. 4. Again its outer fixing bead is sandwiched between the covering ring 174 and the annular projection 324 of the casing 64. The covering ring 174 is kept very small in this embodiment and covers only the outer fixing bead of the membrane 114 and extends up to the annular projection 324 in order to press the membrane airtightly on it. The annular projection 324 is higher in this case and thus ensures a very lirm hold of the membrane 114 along its outer fixing bead 294. For the rest the casing 64 is shaped similar to Figs. l to 6. The piston plate 124 also corresponds to the piston plate (12) of Fig. l, except that its lower side is absolutely plane, without any abutment for a spring, since there is no spring. The operating knob 184, as to its interior structure, also corresponds to that of Fig. 4, but on the outer side it is formed with a handle permitting one to draw out the knob 184 and thus the membrane 114 and the piston plate 124. This handle may take the Shape of an annular recess 494 on the lower side of a knurled ange 564 on the operating knob, so thatV the operating knob 184 can be safelygripped with two lingers. However, other handles may also be provided, such as handles which can be additionally attached, or folding rings or the like.

The `operation of the hand pump of Fig. 7 is the same as that described with reference to Figs. 4 to 6, but in addition it is possible to draw the operating knob 184 and with it the membrane 114 and the piston plate 124 out of the pumping chamber to such an extent that its volume is doubled compared with the position shown in Figs. 1 to 4. Moreover, the final vacuum produced by the pump is no longer dependent on the return force of the membrane or of a separate spiral spring, but it depends only on the very small but unavoidable clearance and the overpressure which is required in order to operate the rubber tube valve 314. The pump `may be operated until it practically does not convey air any longer, which is expressed by the fact that the operating knob 184 with the membrane 114 and the piston plate 124 returns from its outer end position into the completely depressed position without any pressure being exerted on the operating knob. In this position the smooth surface 484 of the operating knob 184 is Hush with the at outer side of the cover or lid 4 of the container. In this case, the residual pressure left in the interior of the evacuated container will be 50 to 100 Torr.

According to Fig. 8 the air admission valve consists of a tubular nipple or socket 51 of the cover or lid 43, which nipple is formed with a central bore 52 extending t0 the lateral valve opening 53 in the upper part ofthe nipple S1. Slipped over the nipple 51 is a rubber tube 54 which is tixedly engaged on the outer side of the nipple and closed at the top 55 thimble-fashion. The lower end of the rubber tube 54 is provided with an annular reinforcement 56 which is extended towards the left in the form of a grip lug 57 formed with flutes 58. The rubber tube S4 and the grip lug are preferably formed integral with each other, of a caoutchouc mass. In order to protect'the air admission valve, a protective cap 59 is placed over the same, which cap is formed with a lateral opening 60 through which projects the grip lug 57. The internal diameter of the protective cap is dimensioned in such a way that excessive drawing of the rubber tube $4 is avoided.

In order to operate the air admission valve, the lug 57 is pulled in an outward direction, the rubber tube 54 is thereby drawn olf from its seat on the valve socket 51 and the air between the rubber tube 54 and the valve socket 51 is admitted into the lateral valve opening 53 and rom there through the bore 52 into the vacuum cham- In the embodiment shown in Fig. 9 the packing ring 33 is of YT-shaped cross section. The vertical leg 61 is inserted in the annular groove 62 of the lid 43, while the horizontal leg 63 is put on the edge of the container 13. A special feature of the packing ring 35 consists in the fact that the leg 61 inserted in the annular groove 62 is formed with an internal annular air cushion 64 which is airtightly closed by the caoutchouc wall of the packing ring. At the outer wall of the lid the annular groove 62 is defined by two annular collars 65 and 66 whose lower edges engage the horizontal leg of the T-shaped cross section and thus force the packing ring 33 towards the wall of the container 13. The internal ring 66 is provided with bores 67 serving for venting the annular groove as the container is evacuated.

This modification operates in such a way that as the air is evacuated from the container 16 by operating the hand pump, the air also ows from the interior of the annular groove 62 between the packing ring 36 and the lid 46 through the bores 67 into the interior of the container 16. The air of the air cushion 64 in the interior of the leg 61 expands and tends to urge the wall of the ring 36 into the container 16. Hereat the leg 61 of the vpacking ring tightly engages the internal surfaces of the annular groove and thus forms a very tight seal.

Fig. l0 shows a particularly favorable embodiment of the packing ring 3". The leg 611 of the packing ring forming the air cushion in this case is shaped considerably longer than in Fig. 9` and extends on both sides beyond the solid leg 631. The lid 4'z of the vacuum container is provided with an annular groove 621, as in Fig. 9, which defines the two collars 651 and 661. The upper leg 611 of ring 3'1 engages the annular groove 621, while the lower leg 611 engages the annular groove 68 provided in the vacuum container 1". The bores 67 for venting the annular groove 621 or 68 are omitted in this case. Instead, the inner ring 661 of the lid 4" and the inner ring 69 of the vacuum container 1" are made somewhat shorter than the outer rings 651 and 7 0.

Theinvention' can' be used for various purposes, for instance, for storing food in' the household or for commercial purposes, for conserving the aroma of such articles as coffee, tea, tobacco, for protecting fruit, vegetables and the like, for preventing pharmaceutical products, such as ointments, or tarts, pastries, and other bakery products from drying out. In the latter case the lid ma',l have the shape of a bell for covering a plate or dish containing the goods.

It has been found out by practical experiences that it is particularly favorable to choose a ratio of the stroke volume of the pumping chamber to the contents of the container of 1:10. In this case by one stroke of the pump a closing pressure of about 0.2 kgs/cm.2 is reached which is sufficient for most practical purposes where it is intended to safely close a container. Such single depression of the operating knob of the pump is much simpler and quicker than the closing of the well known screw lids, bayonet catches or the like.

Where it is intended `to store perishable goods or goods tending to lose their aroma, the hand pump according to the first two embodiments `is advantageously operated up to the final vacuum of 300 to 400 Torr.

For special requirements, such as the storing of opened serum ampullae or other valuable medicine which has to be protected against the action of oxygen, -it is advantageous to use the hand pump according to the invention in the form permitting to attain a final vacuum of 50 to 100 Torr. A preferred application of this form of the hand pump is the evacuation of heat-insulating appliances, such as, thermos bottles which in `a simple form consist of a baby milk bottle with a corresponding jacket of synthetic material or the like, thermos boxes or the like. The pump can also be used for containers serving to preserve any goods whatever.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention it will be understood by those skilled Iin the art after understanding the invention that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended, therefore, Ito cover all such changes and modifications in the appended claims.

I claim:

1. A lid for a vacuum container comprising a hollow enclosed uid tight structure consisting of an inner member formed integrally with said lid and an outer member having an opening, said inner and outer members defining a suction chamber, a suction device secured between said members and including a piston mounted to be reciprocated through said opening of said outer member, valve means in said inner member and in said piston, manual means for actuating said piston to operate said device, the outer face of said piston being disposed outside the topface of said -lid at the beginning of the stroke of said piston and at least iiush with said top face at the end of the stroke of said piston in order to per-mit storing and shipping of said container with said piston in its innermost position wit-hout projecting from said lid, and said piston consisting of a cylindrical .upper part and a truncated cone shaped lower pant, said suction device 10 comprising an annular membrane clamped between said outer and inner members, and said inner member having a truncated cone shaped center part complementary to that of said piston.

2. The lid, as set forth in claim l, which includes a covering ring engaging the outer margin of said membrane and having a circular bore, and said pistonbeing slidable in said circular bore of said ring.

3. The lid, as set forth in claim 1, which includes a return spring for said piston disposed between the latter and said inner member, the force of said spring together with the Ireturn force of said membrane being chosen in such manner that the total return force is insuiiicient to return said piston Ito its initial position when the required vacuum has been reached.

4. The lid, as set forth claim 1, in which said valve means comprises an air exhaust valve having a socket and arranged within the lower part of said piston, said socket leaving in said piston an annular gap adapted for accommodation of a return spring.

5. The lid, as set forth in claim l, in which said valve means comprises a suction valve having a socket, which is arranged in said inner member and leads to a cylindrical bore of said piston, and said socket leaving an annular gap adapted for accommodation of the return spring.

6. The lid, as set forth in claim l, which includes a cover plate disposed below said valve means in said inner member and having a laterally directed inlet slot adapted to be lled with a filtering material.

7. The lid, as set forth in claim 1, in which said suction device includes a membrane hav-ing at least two fixing beads and a tube-like extension, a piston plate and said tube-like extension defining a valve chamber formed in the center of lthe membrane, and a covering ring for connecting said membrane and said piston.

8. rlhe lid, as set forth in claim 7, which includes a spiral spring adapted to be compressed into a plane at the inner face of said inner member.

9. The lid, as set `forth in claim 7, in which said membrane is formed with a first fixing bead at its outer periphery and with at least one further fixing bead within the inner third of its radius.

l0. The lid, as set forth in claim 9, wherein said inner member has an annular projection and in which said outer fixing bead of said membrane is tightly engaged outside of said annular projection of said inner member, and a covering ring on the opposite side of said membrane so that the latter is disposed between said covering ring and said inner member.

l1. rllhe lid, as set forth in claim 7, in which said inner fixing bead of said membrane is inserted in a recess of said piston plate, an operating knob mounted on said piston, and said inner fixing bead being held in its proper position by an annular projection of said operating knob.

12. The lid, as set forth in'elaim 1l, which includes a pull handle incorporated lin said operating knob.

13. The lid, as set forth in claim 7, in which said membrane is inserted in said piston plate by at least tWo inner fixing beads, an operating knob mounted on said piston, and having at least two annular projections and said two inner fixing beads being held in their proper position by said annular projections of said operating knob.

14. The lid, as set forth in claim 13, wherein said operating knob has a recess and in which said piston plate is formed with a cylindrical nipple projecting into said recess of said operating knob, and said membrane has a tubular central projection, and the latter is slipped over said nipple.

15. The lid, as set forth in claim 14, in which said piston plate is formed with a bore extending in the for-m of a lateral recess of said nipple, to about one third of the length of said nipple.

16. The lid, as set forth in claim 15, in which said operating knob has at least one internal annular projection formed with at least one air passage slot, while the lower part of the outer wall of said operating knob is provided with an aperture for the passage of air.

17. The lid, as set forth in claim 16,Y in which said covering ring covers the entire suction device with the exception of said operating knob which in its position of rest projects from said covering ring and n its completely depressed position lies ush with said covering ring, in which said spiral spring being compressed in a plane position and said membrane and said piston plate engaging the inner wall of said inner member in said completely depressed position.

- Y Y 12 18. The lid, as set forth in claim 17, in which said covering ring merely covers the outer head of said membrane and the annular projection of said inner member and apart from said operating knob exposes also the top side of said membrane.

References Cited in the le of this patent UNITED STATES PATENTS 1,946,872 Muhleisen Feb. 13, 1934 2,157,624 Overmyer May 9, 1939 2,436,849 Billeter Mar. 2, 1948 2,506,362 Hofmann May 2, 1950 2,605,957 Houston Aug. 5, 1952

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