Membrane Pump with Bleed Valve

Abstract

A suction pump, in particular a breast pump, comprises a bleed valve with a bleed opening (44, 54, 67), a bleed body (32) which seals the bleed opening and an operating means (8) for operating the bleed body. The bleed body may be operated such that upon opening the valve initially only a partial region of the bleed opening is released and subsequently a greater part thereof or the whole bleed opening is released. Said suction pump provides a large functionality with the smallest size and, furthermore, is cheap to produce and easily assembled.

Description

TECHNICAL FIELD

The invention relates to a method for actuating a suction pump with an air release valve according to the preamble of patent claim 1, a suction pump with an air release valve according to the preamble of patent claims 5 and 19, and a suction pump with a safety valve according to the preamble of patent claim 28.

PRIOR ART

Suction pumps are known for a wide variety of applications. However, they can preferably be used in breast pump devices for pumping off breast milk, or as drainage pumps for suctioning off body fluids.

There are suction pumps in closed systems which at all times move the same air within the pump chamber. However, open pump systems are also known with an air release valve which can be opened cyclically via an electromagnet.

The requirements placed on these suction pumps, in particular when they are used as breast pumps, are quite high. They should be as powerful as possible but, at the same time, relatively small. Particularly in their use as breast pumps, they should be able to operate with minimum maintenance and should be easy to clean.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to make available a method for actuating a suction pump with a safety valve, and to make available a suction pump having an air release valve, both of these permitting the smallest possible design of the pump yet at the same time allowing short pump cycles.

This object is achieved by a method and by a suction pump having the features of patent claims 1 and 5, respectively.

In the method according to the invention, an air release body, which closes an air release opening of the air release valve, is at first only partially lifted. In this way, a smaller force is needed than if the whole air release opening is freed in a single step.

The means for actuating, in particular for lifting, the air release body can therefore be less powerful and can thus be made smaller. If an electromagnet is used as such a means, a relatively low-power type can be used. The reason is that, when pulling up or lifting the air release body, the electromagnet can at first apply less force than it does at the end of the movement. This initially available lower force, however, is sufficient to free a relatively small opening. It is therefore possible to use a relatively small and thus also inexpensive electromagnet. Moreover, the air release opening can be made relatively large. This ensures a rapid cancellation of the underpressure and, therefore, the desired functionality of the pump.

The pump easily reaches 120 cycles per minute. However, it can also operate optimally at a cycle rate of 50-72 cycles per minute. The first cycle rate is particularly suitable for stimulation, the second one for expression of breast milk.

In a preferred variant of the method according to the invention, only an edge area of the air release body is at first removed from the air release opening. A minimal amount of force is needed if this edge area coincides with a corner of the air release body.

The air release body is preferably a membrane. The lifting of its edge area is made easier if the lifted edge area is less thick than the rest of the membrane. The air release opening is preferably polygonal, in particular square or triangular. The membrane too is preferably polygonal, preferably square or triangular.

To permit easier lifting of the membrane, a connecting pin can be secured to it or integrally formed on it, and this connecting pin is connected to an armature of the lifting magnet. This connecting pin is preferably situated in the edge area of the membrane that covers the air release opening. However, the membrane can also be designed with a raised flange, in which case the connecting pin is not arranged over the air release opening but instead on this raised flange.

If the connecting pin is designed so as to be movable relative to the membrane, it is possible to overcome any production-related or assembly-related tolerances. Errors in the angle of the electromagnet can also be compensated. Good results were achieved using a connecting pin which is formed integrally on an air release membrane made of silicone and which, by means of suitable thickening of the material, has sufficient stiffness. It can be formed thereon in a hinged manner. However, in a simple embodiment, the elasticity of the material of the connecting pin suffices to make it movable about its point of attachment.

In another embodiment, the air release body has a first subsidiary body and a second subsidiary body. A first subsidiary body closes the air release opening only partially, since it has an air release channel which creates a connection from the air release opening to the outside. This first subsidiary body including the air release channel can be closed by a second subsidiary body. When air is released, only the first subsidiary body is at first lifted, or distanced from the air release channel, such that only part of the air release opening is freed. The second subsidiary body can then also be distanced from it, such that the whole air release opening is now freed. In this second stage, the second subsidiary body can preferably be actuated jointly with the first subsidiary body.

Compared to this embodiment, the first embodiment mentioned, with the air release membrane that can be actuated in an edge area, has the advantage that it ensures leaktightness and thus, particularly when used in a breast pump, ensures there is no leakage of the pumped-off milk.

A further advantage of the abovementioned embodiments, particularly as regards the use of the membrane, is that no springs are needed, and the number of individual parts required can therefore be reduced. Since no spring has to be fitted, the work involved in assembling the pump is also reduced.

It is a further object of the invention to create a suction pump which can be put together as easily as possible.

This object is achieved by a suction pump having the features of patent claim 19.

The suction pump according to the invention has an air release valve with an air release membrane, and this air release membrane and a vacuum membrane used to generate the vacuum are designed integrally in the form of a common membrane plate.

Arranging the air release valve and the vacuum membrane on the same plate means that these elements are less expensive to produce and are easier to assemble.

In a preferred embodiment, the pump comprises an upper housing part, a middle housing part and a lower housing part, with a membrane plate and a valve plate being arranged between the housing parts. This division means that several elements can be formed on the same structural part. In particular, the vacuum membrane needed to generate the underpressure, and the air release membrane needed to rapidly cancel the underpressure, can be formed integrally on the same structural part. Control flaps and valve flaps can also be formed integrally on a common structural part. Electric motor and electromagnet can be secured in the same housing part. By dividing the pump into several levels, preferably five levels, the number of individual parts can be reduced to a minimum without having to give up the complexity of the pump assembly. This not only reduces the outer dimensions of the pump assembly, but also minimizes the production and assembly costs.

A further advantage of this modular construction with several levels is that the pump can be cleaned by simple flushing, without having to be dismantled into its individual parts. By virtue of the exhaust leading to the outside, no sponge is needed. Such sponges are used in the prior art to absorb milk that has been sucked into the pump and also to attenuate noise. However, they take up space in the pump and tend to give rise to unpleasant odor.

This modular construction can also be used in a pump that does not have the abovementioned air release valve according to the invention.

It is a further object of the invention to make available a suction pump which has a safety valve and which cannot be inactivated by liquid, in particular milk, that has been sucked into the pump and has accumulated there.

This object is achieved by a suction pump having the features of patent claim 28.

The suction pump according to the invention has a safety valve with a first stage which opens at a first underpressure, and with a second stage which opens at a second underpressure. The first underpressure is quantitatively lower than the second.

This two-stage design of the safety valve ensures that milk cannot get as far as the second stage. Since the first stage opens even in the event of a very slight deviation from the ideal underpressure, it will still open, in the event of clogging, when the underpressure is at a higher level, that is to say in an emergency situation. The second valve prevents the entire safety valve from opening at too small a deviation, but it still opens reliably in an emergency situation. This two-stage safety valve can also be used in a pump that does not have the abovementioned air release valve according to the invention or the modular construction.

The suction pump according to the invention can therefore reduce the vacuum in a relatively short time and without too much force. The pump according to the invention is suitable for a wide variety of applications. It is suitable in particular as a breast pump for suctioning off breast milk and as a drainage pump for suctioning off body fluids. The pump assembly according to the invention is suitable in particular for use in a portable breast pump, as is described in particular in still to be published PCT/CH 2004/000061.

Further advantageous embodiments are set forth in the attached patent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is explained below on the basis of preferred illustrative embodiments depicted in the attached drawings, in which:

FIG. 1 shows a perspective view of the suction pump according to the invention without outer housing;

FIG. 2 shows a view of the suction pump according to FIG. 1 from below;

FIG. 3 shows a longitudinal section through the suction pump according to FIG. 1;

FIG. 4 shows an exploded view of the suction pump according to FIG. 1;

FIG. 5 shows a perspective view of a lower housing part of the suction pump according to FIG. 1;

FIG. 6 shows a view of a membrane plate of the suction pump according to FIG. 1 from above;

FIG. 7 shows a longitudinal section through the membrane plate according to FIG. 6;

FIG. 8 shows an enlarged detail of the membrane plate according to FIG. 7;

FIG. 9 shows a view into a part of the upper housing part from above;

FIG. 10 shows a view of a membrane plate of the suction pump according to a second embodiment from above;

FIG. 11 shows a longitudinal section through the membrane plate according to FIG. 10;

FIG. 12 shows an enlarged detail of the membrane plate according to FIG. 11, and

FIG. 13 shows a longitudinal section through an air release unit according to the invention in a third embodiment.

EMBODIMENTS OF THE INVENTION

FIG. 1 shows a suction pump according to the invention, such as is suitable in particular for a breast pump device for pumping off human breast milk. However, the pump is also suitable for other applications, for example for drainage pumps for suctioning off body fluids.

Only the actual pump assembly is shown. This assembly is usually arranged in an outer housing. The figure does not show this outer housing and the electronics needed for actuating the pump, or any energy storage means, for example an accumulator or battery.

The pump has an extremely compact structure. One of its largest elements is an electric motor 1. It also has an upper housing part 2, a middle housing part 4 and a lower housing part 6, which can be plugged together. An attachment part 7 is also provided which is a component part of these housing parts or, as is the case here, is plugged onto them.

On the attachment part 7, there is at least one breast shield attachment piece 70 on which a connecting tube to a breast shield can be plugged. The attachment part 7 also comprises an exhaust 71. This exhaust 71 also leads out of the outer housing. An air release channel 72, also protruding from the outer housing, and spacer elements 73 are also present. The spacer elements 73 brace the pump assembly in relation to an outer housing in such a way that vibrations cannot be transmitted and a sufficient sound insulation is ensured.

It will be seen from FIG. 2 how the individual attachments 70, 71, 72 are connected via individual channels to the individual areas of the pump.

The longitudinal section shown in FIG. 3 through the pump, now without motor 1, shows that the pump, despite its compact design, is divided into three clearly distinguishable function areas: a pump unit P, an air release unit V and, arranged between these, a safety unit S. The structure of the pump can best be seen from an overview of FIGS. 3 and 4.

The pump unit P comprises a vacuum membrane 31 and inlet and outlet control flaps 51, 52 which, together with inlet and outlet openings 62, 63 and with a pump chamber opening 43′, create a connection between a pump chamber 43 and a vacuum channel 69. The vacuum membrane 31 is connected to a drive shaft 10 of the electric motor 1 via a connecting rod 11, coupling piece 12, for example a ball bearing, and eccentric 13 and, by means of this motor 1, it can be lifted and lowered according to a predetermined rhythm or pump curve or according to a rhythm or pump curve that can be freely selected via a control system.

The air release unit V comprises an air release valve with an air release membrane 32, and an air release opening which can be closed tightly by the latter and is in the form of an air release membrane seat 44. The chamber 44′ surrounding the air release membrane seat 44 is connected via an air release attachment 45 to the air release channel 72. The air release membrane seat 44 is open at the bottom, that is to say on the side directed away from the air release membrane 32, and adjoins a first air release opening 54 of the valve plate 5 and a second air release opening 67 of the lower housing part 6. This second air release opening 67 is connected via the vacuum channel 69 to a safety valve chamber 68 and to the inlet opening 62.

The air release membrane 32 is connected via a connecting pin 33 to an armature 80 of a lifting magnet or electromagnet 8. The electromagnet 8 lifts the air release membrane 32 and thus frees the air release membrane seat 44. By this means, air passes through the air release channel 72 and through the first and second air release openings 54, 67 into the vacuum channel 69, and the underpressure in the latter is reduced. This lifting and lowering of the air release membrane 32 also takes place according to a predetermined function or according to a function that can be freely selected via a control system, and which function is coordinated with the movement of the vacuum membrane 31. The movements of the vacuum membrane 31 and of the air release membrane 32 are preferably coordinated in such a way that a pump curve is obtained which is as described in WO 01/47577 and which is adapted to the needs of mother and child or imitates the natural sucking rhythm of a baby. The assembly functions in all positions, that is to say, for example, when it is lying or standing on a table or being carried. The vacuum generated is largely independent of how the assembly is spatially arranged.

The safety unit S comprises a safety valve. In the event of a malfunction or failure of the control electronics that coordinate the movement of the vacuum membrane 31 and of the air release membrane 32, this safety valve ensures that the level of the underpressure in the pump does not become too great and injure the mother's breast.

According to the invention, the safety unit S is designed with two stages. The first stage consists of a first safety membrane 55 and of a semispherical safety valve closure 46 which has a small lateral opening 46′ and which presses on the first safety membrane 55. This first stage opens even at a low underpressure of about 120 mmHg.

The second stage comprises a second safety membrane 35 which is closed by means of an adjusting screw 9. Its limit value, at which it opens, can be modified by adjustment of the adjusting screw 9. According to the invention, it opens at a higher underpressure than the first stage, for example at about 290 mmHg.

If milk or another suctioned fluid accidentally gets into the pump, it settles in the area of the first stage and cannot pass through to the second stage via the chamber lying in between. At the very most, therefore, it can cover the first safety membrane 55. In this covered state, the latter possibly no longer opens at the preset value, but it always opens early enough to permit release. The second membrane always opens only when the limit value is actually exceeded and the pump has to be relieved. Since the second stage cannot be soiled, it always opens reliably.

The individual parts of the pump can best be seen in FIG. 4. This exploded view shows that the pump is divided into several levels I, II, III, IV and V, where parts of the pump unit P, of the safety unit S and of the air release unit V are arranged on common levels.

A first level I, which usually, but not necessarily, forms the uppermost level in the operating position, comprises the upper housing part 2, the aforementioned motor 1, and the electromagnet 8. The motor 1 is secured by fastening screws 21 onto a motor plate 20 of the upper housing part 2. The motor can be screwed onto the motor plate 20 and can likewise be plugged onto the pump assembly. The housing part 2 comprises a connecting rod chamber 23 which is used to receive the connecting rod 11, the ball bearing 12 connected thereto, and an eccentric with counterweight 13. The counterweight 13 does not necessarily have to be present. The upper housing part 2 also comprises a magnet chamber 24 which is separate from the connecting rod chamber 23 and in which the electromagnet 8 is secured. At its lower end, the upper housing part 2 has upper locking clips 22 which protrude downward.

The adjusting screw 9 for the second stage of the safety valve is also arranged adjustably in the upper housing part 2.

The second level II is defined by a membrane plate 3 which extends at least approximately across the whole base surface of the upper housing part 2 and thus of the pump assembly. The membrane plate 3 is made of a flexible material, in particular silicone, and is relatively thin. It has centering holes 30 in its edge areas, and upper and lower sealing lips 34, 34′, 34″ which ensure an airtight and liquid-tight connection to the upper housing part 2 and middle housing part 4, respectively. The lower sealing lips can be seen in FIG. 7. The membrane plate 3 comprises the air release membrane 32, which is designed in the shape of a triangle. As can be seen in FIG. 6, the air release membrane 32 has a triangular basic shape. This triangle is divided into two subsidiary areas, where a first subsidiary area 32′ again forms a triangle, and the second subsidiary area 32″ is formed by the remaining part of the membrane and thus has a trapezoid shape. A first corner of the first subsidiary area 32′ coincides with a corner of the air release membrane 32. An opposite side of the first subsidiary area 32′ extends parallel to an opposite side of the air release membrane 32, and the two other sides of the triangle of the first subsidiary area 32′ extend congruently with respect to the sides of the triangle of the air release membrane 32. The triangular first subsidiary area 32′ is less thick than the second subsidiary area 32″, as can be seen in FIGS. 7 and 8.

The connecting pin 33 is formed integrally on the free corner of the first subsidiary area 32′. As can also be seen from FIGS. 7 and 8, it projects upward at least approximately perpendicular to the plane of the membrane and is fixedly connected to the armature 80. The air release membrane 32 is surrounded by a first sealing lip 34.

The membrane plate 3 further comprises the vacuum membrane 31, which is connected to the connecting rod 11. The connecting rod 11 can be formed integrally on the vacuum membrane 31 by material thickening and can be composed of a two-component material. It can also be produced separately, however, and be connected to the membrane 31 during assembly. The vacuum membrane is sealed off from the upper and middle housing parts 2, 4 by means of a second sealing lip 34′.

The membrane plate 3 further comprises the second membrane 35 of the safety valve. The latter, as can best be seen in FIG. 7, has a v-shaped opening that widens toward the bottom and is sealed off from the upper and middle housing parts 2, 4 by means of a third sealing lip 34″ that surrounds it.

The third level III is formed by the middle housing part 4. Like the upper and lower housing parts 2, 6, it is preferably made of a solid plastic material, for example POM (polyoxymethylene). The middle housing part 4 is panel-shaped and has a plane upper face and a plane lower face. On its side faces, it is provided with upwardly and downwardly directed catches 40, 41, respectively, the upper catches 40 engaging into the upper locking clips 22 of the upper housing part 2, and the lower catches 41 engaging into lower locking clips 60 of the lower housing part 6. Centering holes 42 are also present which are in alignment with the centering holes 30 of the membrane plate 3.

Two recesses, closed at the bottom and with small lateral connecting openings, are present in the middle housing part 4. One of these recesses forms the vacuum membrane seat 43 for the vacuum membrane and thus defines the pump chamber. A second of these recesses forms a safety closure 46 of the first safety stage. The chamber 44′, with the membrane seat 44 arranged therein for the air release membrane 32, is also present in the middle housing part 4. This seat 44 has a triangular shape in this example. The chamber 44′ is a recessed, h-shaped trough, the latter being connected to the air release attachment 45.

The fourth level IV in turn comprises a flexible plate, preferably of silicone. It is formed by a valve plate 5. This too has centering holes 50, at least one pair of these centering holes 50 being in alignment with the centering holes of the middle housing part 4 and of the membrane plate 3.

The valve plate 5 comprises a first control flap 51, which forms an inlet for the vacuum chamber. It further comprises a second control flap 52, which forms an outlet for the vacuum chamber. Leading away from the second control flap 52, there is a double sealing lip 53 which surrounds an upwardly open connecting channel 64 arranged in the lower housing part 6 and seals this connecting channel 64 at the top.

The first membrane 55 of the safety valve is also formed integrally in the valve plate 5. The latter also comprises the first air release opening 54, which ensures a connection between the air release membrane seat 44 and a second air release opening 67, which is arranged in the lower housing part 6. The individual elements of the valve plate 5 are in turn provided with upper and lower sealing lips to seal them relative to the middle and lower housing parts 4, 6. All the elements of the valve plate 5 are preferably produced integrally with the latter.

The fifth level V comprises the lower housing part 6 and the attachment part 7. These two parts can be formed by a single common part, or, as is shown here, they can be coupled to one another by plug connections.

The lower housing part 6 is shown in FIG. 4, and in another perspective view in FIG. 5. It also has a plate-shaped design, its underside forming the base of the pump assembly. The lower locking clips 60 project upward at the sides, such that the lower catches 41 of the middle housing part 4 can lock into them. Centering pins 61 are also present which also project upward and can be guided through the centering holes 30, 42, 50 of the membrane plate 3, of the middle housing part 4 and of the valve plate 5. These centering pins and centering holes make it easier to stack the individual levels on one another and thus permit rapid assembly.

The lower housing part 6 further comprises a first circular recess with central elevation, which forms an inlet opening 62. A second circular recess forms an outlet opening 63. This inlet opening 62 is connected to the vacuum channel 69 extending in the inside of the lower housing part 6. This channel 69 first passes through the safety valve opening 68 which is likewise designed as a trough and over which the safety membrane 55 of the first stage is arranged.

The connecting channel 64, open at the top and sealed off by the sealing lip 53, extends in the lower housing part 6 and opens into the outlet opening 63. This connecting channel 64 is connected to the second air release opening 67 present in the lower housing part 6.

As can be seen in FIG. 5, the connecting channel 64 ends in an exhaust attachment 66 which can be plugged into the exhaust 71. The second air release opening 67 leads to a breast shield attachment part 65, which is connected to the breast shield attachment piece 70.

This construction permits simple cleaning of the pump. If milk or another suctioned liquid gets into the pump, the latter can simply be flushed with water or air, the cleaning medium being pressed or blown in through the beast pump attachment piece 70 and leaving the pump again by way of the air release channel 72 and the exhaust 71.

FIG. 9 shows a partial view from above into the upper housing part 2. As can be seen here, the adjusting screw 9 of the safety valve S is designed with a round cross section but is screwed into a square thread opening 25. This means that a sufficient passage of air is at all times ensured.

FIGS. 10 to 12 show a second embodiment. This embodiment differs from the one described above in the area of the air release valve. The other parts are of the same design and are therefore not described again here. In this example, the air release membrane 32 is not triangular, but square. However, it can also be hexagonal or octagonal or of any desired polygonal shape. It has been found in practice, however, that the square shape closes and opens more reliably compared to the triangular shape. The air release membrane is once again divided into thick and thin subsidiary areas 32′, 32″, the connecting pin 33 being arranged on the thin subsidiary area 32′. The two subsidiary areas 32′, 32″ are also substantially square, the connecting pin 33 being arranged on a long side of the thin subsidiary area 32′ directed away from the thick subsidiary area 32″. It is now no longer secured in a corner, but approximately midway along this long side, as can be seen in FIG. 10. It has also been found that the functionality is better ensured if the connecting pin is integrally formed on the side wall 44″ of the chamber 44′, as is shown in FIG. 12. However, the opening lying below this, that is to say the air release membrane seat 44, is preferably triangular as before. In this case, the connecting pin 33 is preferably arranged exactly over the corner of the triangular hole 44.

FIG. 13 shows a further embodiment of the air release valve according to the invention. The rest of the pump can be designed the same way as described above and is therefore not shown again here. The air release body is not a membrane here, but instead is formed by first and second air release blocks 320, 321.

The first air release block 320 is fixedly connected to the armature 80 of the lifting magnet 8. It is connected to the second air release block 321 via a first, soft spring element 322 and a retaining clip 323. The retaining clip 323 is secured, via a second, harder spring element 324, on a base body 325 surrounding the air release body. The base body 325, the first air release block 320, the retaining clip 323 and the two spring elements 322, 324 are preferably made of plastic and are all designed together in one piece.

The second air release block 321 has a first air release channel 326, which can be closed by the first air release block 320. The second air release block 321 closes a second air release channel 327, which is connected to the vacuum channel 69. The second air release channel 327 has a greater diameter than the first air release channel 326.

If the armature 80 of the magnet 8 is now lifted, the soft spring element 322 means that only the first air release block 320 is lifted at first and the first air release channel 326 is freed. If the armature 80 is lifted further, the magnet is then more powerful and, despite the harder spring element 324, is able to lift the second air release block 321 and thus free the second air release channel 327. A connection is thereby created now between the first air release channel 326 and the vacuum channel 69, and the underpressure in the pump is reduced. As an alternative or in addition to the springs of different strength, abutment elements can be provided which limit the travel of the first and second springs.

Therefore, in this embodiment too, the air release body is lifted such that it at first only frees part of the air release opening, with the result that less force is needed at the beginning of the lifting movement than at the end of the movement.

The suction pump according to the invention therefore affords several advantages. It provides wide-ranging functionality within a very small space and can also be produced inexpensively and is easy to assemble.

LIST OF REFERENCE SIGNS

P pump unit

V air release unit

S safety unit

I first level

II second level

III third level

IV fourth level

V fifth level

1 motor

10 drive shaft

11 connecting rod

12 ball bearing

13 eccentric with counterweight

2 upper housing part

20 motor plate

21 fastening screws

22 upper locking clip

23 connecting rod chamber

24 magnet chamber

25 thread opening

3 membrane plate

30 centering hole

31 vacuum membrane

32 air release membrane

32′ first subsidiary area

32″ second subsidiary area

33 connecting pin

34 first sealing lip

34′ second sealing lip

34″ third sealing lip

35 second membrane of the safety valve

320 first air release block

321 second air release block

322 first spring element

323 retaining clip

324 second spring element

325 base body

326 first air release channel

327 second air release channel

4 middle housing part

40 upper catches

41 lower catches

42 centering hole

43 vacuum membrane seat

43′ pump chamber opening

44 air release membrane seat

44′ chamber

44″ side wall

45 air release attachment

46 safety valve closure of first stage

46′ lateral opening

5 valve plate

50 centering hole

51 first control flap

52 second control flap

53 sealing lip for connecting channel

54 first air release opening

55 first membrane of the safety valve

6 lower housing part

60 lower locking clip

61 connecting pin

62 inlet opening

63 outlet opening

64 connecting channel

65 breast shield attachment part

66 exhaust attachment

67 second air release opening

68 safety valve chamber

69 vacuum channel

7 attachment part

70 breast pump attachment piece

71 exhaust

72 air release channel

73 spacers

8 lifting magnet

80 armature

9 adjusting screw

Claims

1. A method for operating a suction pump, in particular a membrane pump for generating a vacuum, the suction pump having an air release valve with an air release body which frees an air release opening at cyclical time intervals and closes it sealingly again, characterized in that the air release body is lifted in such a way that it at first only partially frees the air release opening.

2. The method as claimed in claim 1, in which the air release body is at first removed from the air release opening at an edge area.

3. The method as claimed in claim 2, in which the air release body is at first removed at a corner of the air release opening.

4. The method as claimed in claim 1, in which a first part of the air release body is at first lifted in order to free a first air release channel, and a second part of the air release body is then lifted in order to free a second air release channel, the second air release channel having a greater diameter than the first air release channel, and the two channels being connected to one another.

5. A suction pump with an air release valve, the air release valve having an air release opening, an air release body which can close the air release opening sealingly, and an actuating means for actuating the air release body, characterized in that the air release body can be actuated in such a way that, upon opening of the valve, it at first frees only a partial area of the air release opening and thereafter frees a larger partial area or the entire air release opening.

6. The suction pump as claimed in claim 5, in which the air release body is an air release membrane, and in which the air release membrane has an edge area at which it can at first be removed from the air release opening upon opening of the valve.

7. The suction pump as claimed in claim 6, in which the actuating means is a lifting magnet, and the air release membrane is connected to an armature of the lifting magnet via a connecting pin, and the connecting pin is connected to the air release membrane at this edge area thereof.

8. The suction pump as claimed in claim 7, in which the connecting pin is arranged over a corner of the air release opening.

9. The suction pump as claimed in claim 7, in which the connecting pin is formed integrally on the air release membrane.

10. The suction pump as claimed in claim 7, in which the connecting pin is arranged approximately perpendicular to the air release membrane.

11. The suction pump as claimed in claim 6, in which the air release membrane is made of a plastic, in particular of silicone.

12. The suction pump as claimed in claim 6, in which the air release membrane has at least one corner, and the edge area comprises at least one of the at least one corner.

13. The suction pump as claimed in claim 6, in which the air release membrane has a polygonal basic shape, in particular a square or triangular basic shape.

14. The suction pump as claimed in claim 6, in which the air release membrane has a first partial area with a lesser thickness and a second partial area with a greater thickness, and in which the edge area is arranged in the first partial area.

15. The suction pump as claimed in claims 13 or 14, in which the air release membrane has a square basic shape, in which the two partial areas each have a square basic shape, and in which the connecting pin is arranged on a long side of the thinner partial area directed away from the thicker partial area.

16. The suction pump as claimed in claim 15, in which the long side has a center, and in which the connecting pin is arranged in the area of this center on the thin partial area.

17. The suction pump as claimed in claim 5, in which the air release opening has a polygonal basic shape, in particular a square or triangular basic shape.

18. The suction pump as claimed in claim 6, in which the air release membrane is substantially plane.

19. A suction pump with an air release valve in which the air release valve has an air release membrane, and in which this air release membrane and a vacuum membrane used to generate the vacuum are designed integrally in the form of a common membrane plate.

20. The suction pump as claimed in claim 19, in which a part of this membrane plate is designed as a safety membrane of a safety valve.

21. The suction pump as claimed in claim 15, in which the pump comprises an upper housing part which receives a lifting magnet for actuating the air release membrane and receives an electric motor for actuating the vacuum membrane, a middle housing part with an air release membrane seat which is provided for the air release membrane and which surrounds an air release opening, and with a vacuum membrane seat for the vacuum membrane, and a lower housing part for forming a vacuum channel between air release opening and an inlet opening of the vacuum membrane seat, the membrane plate being arranged between the upper and middle housing parts, and a valve plate being arranged between the middle and lower housing parts.

22. The suction pump as claimed in claim 21, in which the valve plate and the membrane plate are substantially plane.

23. The suction pump as claimed in claim 21, in which the valve plate and the membrane plate are made of a plastic, in particular of silicone.

24. The suction pump as claimed in claim 5, comprising an exhaust and, optionally, a vacuum attachment and an air release attachment which protrude from an outer housing of the pump.

25. The suction pump as claimed in claim 21, in which an exhaust attachment is formed integrally on the lower housing part and can be connected to the exhaust formed integrally on an attachment part.

26. The suction pump as claimed in claim 21, in which the lower, middle and upper housing parts can be plugged together so as to form a closed housing assembly.

27. The suction pump as claimed in claim 26, in which the housing assembly is substantially watertight and can be flushed through via a breast pump attachment to the exhaust and the air release opening.

28. A suction pump with a safety valve in which the safety valve has a first step which opens at a first underpressure, and a second step which opens at a second underpressure, the first underpressure being quantitatively lower than the second.

29. The suction pump as claimed in claim 5, in which the air release body has first and second subsidiary bodies, the first subsidiary body being connected to an armature of a lifting magnet, and the second subsidiary body being connected to the first subsidiary body via a first spring element, and the second subsidiary body having a first air release channel which can be closed by the first subsidiary body, the second subsidiary body closing a second air release channel, and the second air release channel having a greater diameter than the first air release channel.

30. The suction pump as claimed in claim 20, in which the pump comprises an upper housing part which receives a lifting magnet for actuating the air release membrane and receives an electric motor for actuating the vacuum membrane, a middle housing part with an air release membrane seat which is provided for the air release membrane and which surrounds an air release opening, and with a vacuum membrane seat for the vacuum membrane, and a lower housing part for forming a vacuum channel between air release opening and an inlet opening of the vacuum membrane seat, the membrane plate being arranged between the upper and middle housing parts, and a valve plate being arranged between the middle and lower housing parts.

31. The suction pump as claimed in claim 22, in which the valve plate and the membrane plate are made of a plastic, in particular of silicone.

32. The suction pump as claimed in claim 24, in which an exhaust attachment is formed integrally on the lower housing part and can be connected to the exhaust formed integrally on an attachment part.