US20100086419A1

US20100086419A1 - Membrane Suction Pump Unit

Info

Publication number: US20100086419A1
Application number: US12/530,996
Authority: US
Inventors: Christoph Rebsamen; Marcel Felber
Original assignee: Medela Holding AG
Current assignee: Medela Holding AG
Priority date: 2007-03-13
Filing date: 2008-03-04
Publication date: 2010-04-08
Also published as: TW200900586A; CN101636585B; EP2129915A2; WO2008110022A3; RU2009136224A; RU2472967C2; AU2008226308A1; CN101636585A; KR20090118065A; CA2679865A1; BRPI0808211A2; WO2008110022A2; JP2010520962A; MX2009009807A

Abstract

A membrane suction pump unit has a dimensionally stable membrane frame (1), a dimensionally stable monobloc membrane cover (3), which has a pump chamber (31) with a floor region and a side wall (36) encircling the floor region and widening outwards away from the floor region, and a monobloc pump membrane (2), which has a membrane plate (20), a flexible membrane piston (21), at least one inlet valve flap (23) and at least one outlet valve flap (24). The membrane plate (20) is arranged between the membrane frame (1) and the membrane cover (3), and membrane frame (1), pump membrane (2) and membrane cover (3) are connected to one another by means of connecting elements (15, 15′, 15″) in a preset position. The membrane piston (21) passes through the membrane frame (1), and the membrane piston (21) covers a pump chamber (31) of the membrane cover (3). According to the invention, there are more than three connecting elements (15, 15′, 15″), forming a material and/or positive fit.

Description

TECHNICAL FIELD

The invention relates to a membrane suction pump unit according to the preamble of claim 1.

STATE OF THE ART

A generic membrane pump unit as part of a breast pump is known for example from U.S. Pat. No. 4,964,851. The breast pump has an electromotor, a piston rod powered by the motor, and a connected pump membrane. The pump membrane is held in a membrane frame and together with a membrane cover forms a pump chamber. In the commercially available pump, the membrane frame, pump membrane and membrane cover are connected to one another by means of a press connection, with three pins of the membrane frame being held frictionally engaged in corresponding openings in the membrane cover.
U.S. Pat. No. 7,070,400 also discloses the same type of membrane pump unit of a suction pump, where the membrane has a membrane piston with rear depressions. The membrane cover defines a space with a flat floor section and a circular side wall widening conically outwards. This space is covered by the membrane piston and forms the pump chamber.
EP 0 744 180 likewise describes a membrane suction pump which now however is suited for simultaneous use of two suction connectors.
WO 2006/032156 also shows a membrane pump with three housing parts which are interconnected by snap elements.

DESCRIPTION OF THE INVENTION

It is an object of the invention to provide a membrane suction pump unit which has increased processing stability.
This object is achieved by a membrane suction pump unit having the features of claim 1.
The inventive membrane suction pump unit has a dimensionally stable membrane frame, a dimensionally stable monobloc membrane cover, which has a pump chamber with a floor region and a side wall encircling the floor region and widening outwards away from the floor region, and with a monobloc pump membrane which has a membrane plate, a flexible membrane piston, at least one inlet valve flap and at least one outlet valve flap, and a monobloc pump membrane with a membrane plate, a flexible membrane piston and with at least one inlet valve flap and at least one outlet valve flap, the membrane plate being arranged between the membrane frame and the membrane cover, and membrane frame, pump membrane and membrane cover being connected to one another by means of connecting elements in a preset position. The membrane piston passes through the membrane frame and, together with the membrane cover, it forms a pump chamber or covers the pump chamber. According to the invention, there are more than three connecting elements, forming a material and/or positive fit.
The connecting elements connect the membrane frame and the membrane cover with each other and the pump membrane is hold between membrane frame and membrane cover. The connecting elements can penetrate the pump membrane or the pump membrane can be hold between them.
The material and/or positive fit ensure that the connection cannot be broken automatically or by vibrations. In the case of the previously used frictional engagement, it is possible for the connection between the individual parts, i.e. frame, membrane and cover, to be broken, in particular if the pump triggers vibrations in the range of the natural oscillation of the device.
Assembly is also simplified. Assembly is usually carried out manually. This proves easier in practice if there are several connecting elements and thus positions than when three corresponding positions have to be manually brought into alignment. The danger of jamming is hereby lessened.
Although using more than three connecting elements would actually result in static uncertainty, it has been shown that improved overall dimensional stability is attained. The result of using more than three, in particular from six to twelve, connecting elements is thus greater stability and overall rigidity of the device. As a result, membrane cover and membrane frame can distort less, and the unit exhibits increased tightness, or the danger of the unit becoming leaky due to fluctuations in temperature, vibrations or material fatigue is minimized. Preferably, nine connecting elements are used, which are distributed around the edge area.
The use of several connecting elements also increases the characteristic frequency of the system. Acoustic properties are improved, and the tendency to background noise during the pumping procedure is reduced.
The connecting means are preferably pins which are fixed in the seats. They can for example be bonded, welded or riveted. Positive locking elements, for example snap hooks, pine-tree snap locks and similar means, can also be used in place of pins, however.
It is also possible to use positive and material locking, for example via welded pine-tree snap locks.
In a preferred embodiment, the membrane cover has over its entire surface an approximately uniform thickness.
This also prevents warping and deformation and boosts tightness.
The inventive suction pump unit can be manufactured cost-effectively, in particular because it comprises only three parts, of which the two dimensionally stable parts, membrane frame and membrane cover, can be made from plastic in an injection moulding process, and the pump membrane can preferably be made from liquid silicone in an injection moulding process.
This suction pump unit is preferably used in breast pumps for expressing breast milk. However, it is also suitable for other suction pumps, for example drainage pumps.
Further advantageous embodiments will emerge from the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention will be explained hereinbelow by way of a preferred exemplary embodiment, illustrated in the attached drawings in which:

FIG. 1 shows a perspective exploded view of the inventive membrane suction pump unit from above;

FIG. 2 shows a perspective exploded view of the membrane suction pump unit as per FIG. 1 from below;

FIG. 3 shows a perspective illustration of the membrane frame;

FIG. 4 shows a perspective illustration of the membrane cover in a second embodiment;

FIG. 5 shows a perspective illustration of a fastening pin;

FIG. 6 shows a membrane frame with electromotor in an exploded view, and

FIG. 7 shows a perspective exploded view of the membrane suction pump unit in a further embodiment.

WAYS OF CARRYING OUT THE INVENTION

Direction particulars such as above and below are used hereinafter. These refer solely to the arrangement of the individual parts in the figures and do not refer to the position of installation of the inventive membrane suction pump unit in a suction pump.
The inventive membrane suction pump unit as per FIG. 1 has a membrane frame 1, a pump membrane 2 and a membrane cover 3. All these parts are preferably of monobloc design. Membrane frame 1 and membrane cover 3 are dimensionally stable and preferably manufactured in an injection moulding process from plastic, for example thermoplastic, such as polyester. The pump membrane 2 is also monobloc and made in an injection moulding process from liquid silicone.
The membrane frame 1 has a plane-parallel base plate 10 with a round through hole 11. Formed at one end of the base plate 10 and vertical thereto is a stop plate 16. This stop plate 16 has a pump unit seat 19, in which a valve unit, not illustrated here, for example as disclosed in U.S. Pat. No. 4,964,851, is housed. In the seat 19 there is a suction opening 18 in the stop plate 16, which merges into an air intake 18′ on the rear side visible in FIG. 2.
On the side of the base plate opposite the stop plate 16 there is an electromotor 4, illustrated in FIG. 6, which is connected to the later described piston connector 26 of the pump membrane via a piston rod, not illustrated.
As is evident from FIG. 2, the stop plate 16 is provided with an inlet opening 13, pointing to the pump membrane 2. This inlet opening 13 is connected to the exterior via a connecting channel 13″ and an inlet channel 13′ connected to the latter. This is shown in FIG. 3.
The base plate 10, as is again now evident in FIG. 1, also has a channel 10′ on its surface, which channel terminates in the stop plate 16 in a through hole 10″. This serves to assemble a vacuum adjustment pin, not illustrated here.
On the underside of the base plate 10, evident in FIG. 2, is a first circular sealing groove 12. It encloses the through hole 11, the inlet opening 13 and a groove forming an outlet channel 14. This outlet channel is arranged on the side of the through hole 11 diametrically opposite the inlet opening 13 and terminates on a side edge of the base plate 10. At this end the base plate has an upper channel connection 17 in the form of a protruding nose having a U-shaped longitudinal section.
On the base plate 10, connecting elements are formed that project downwards to the pump membrane. In this embodiment these connecting elements are substantially cylindrical pins 15, 15′, 15″, although other connecting elements such as snap lock elements can be present. In this case the snap lock elements are formed preferably on the outer edges of the base plate. This second embodiment is illustrated in FIG. 7. Formed on the membrane frame 1, on the circular front faces, are hooks 151, and on the membrane cover 3 there are matching snap-in shackles 152. The pump membrane 2 needs no connecting elements, rather it is simply held clamped between membrane cover 3 and membrane frame 1.
The pins 15, 15′, 15″ according to the first embodiment are arranged preferably exclusively in the edge region of the base plate 10 and outside the sealing groove 12, distributed over the periphery. There are more than three pins 15, 15′, 15″. In the illustrated example there are nine pins, with preferably six to twelve pins being used.
In a simplified embodiment, all pins are configured the same length and same thickness. However, pins of varying shape may also be used, as is the case here. Some pins, preferably at least two opposing pins 15″, are designed as positioning pins and have a basic cylindrical body and a tapering or tapered tip. Some pins, here first pins 15, have a larger diameter than second pins 15′. The pins 15, 15′, 15″ can also be equipped with vertical ribs 150, as shown in FIG. 5.
The length of the pins 15, 15′, 15″ is such that they pass through the pump membrane 2 arranged behind and project at least partially into the membrane cover 3 or likewise pass preferably completely through this and terminate at its opposite surface.
It is also possible that the pins are formed on the membrane cover or that some of the pins are arranged on the membrane frame and some on the membrane cover, as illustrated in FIG. 4.
The pump membrane 2 arranged beneath the base plate 10 has a likewise substantially plane-parallel membrane plate 20. This membrane plate 20 has approximately the same base surface as the base plate 10. In the middle region of the membrane plate 20, the latter merges into a membrane piston 21, which projects upwards of the membrane plate 20 to the base plate 10. The membrane piston 21 is designed as a cap shape, and preferably has annular circular recesses. Formed in the middle of the membrane piston 20 is the piston seat 26 in the form of a hollow cylinder. The piston can easily plug into this seat 26 and is held therein positively and non-positively.
Located on one side of the membrane piston 21 is a horseshoe-shaped inlet valve flap 23. On the opposite side of the membrane piston 21, the membrane plate 20 has two likewise substantially horseshoe-shaped outlet valve flaps 24 arranged at a distance apart. There can also be more than one or fewer than two valve flaps 23, 24.
The membrane plate 20 has an upper sealing lip 22 which, on the top side facing the base plate 10, encloses the membrane piston 21 and the valve flaps 23, 24, and which is self-contained and projects upwards.
The membrane plate 20 similarly has on its underside facing the membrane cover 3 a circular lower sealing lip 28, which likewise encloses membrane piston 21 and valve flaps 23, 24 and projects downwards. The two sealing lips 22, 28 are preferably congruent.
It is however also possible that only one of the two sealing lips is present, or that they are not congruent. Instead of the sealing lips, sealing grooves could also be in place, and the membrane cover and/or the membrane frame are provided with a corresponding sealing lip or edge.
Formed on a side edge of the membrane plate 20 is a protruding nose 27 projecting over the edge, but otherwise flush with the top side and underside of the plate 20.
Outside the sealing lips 22, 28 the membrane plate 20 is penetrated by first and second fastening holes 25, 25′, the diameters of which preferably correspond to the associated pins 15, 15′, 15″ of the base plate 10, or are slightly larger.
The membrane cover 3 has a cover plate 30, the top side of which pointing to the pump membrane 2 is likewise designed substantially plane. Its underside on the other hand is structured as is described hereinbelow. Formed in the middle of the cover plate 30 is a pump chamber 31, which has a floor region at the same level as the surface of the remaining cover plate 30 and a raised circular side wall 36, the side wall being designed to incline upwards and outwards, so that the opening widens out over the floor region. The side wall 36 can be designed straight oblique or, as shown here, curved.
The side wall 36 is penetrated by at least one inlet channel, here three inlet channels 33′ running parallel to one another. These channels 33 come from an inlet basin 33, which is designed as a recess in the cover plate 30 and terminate in the floor region at a distance from the side wall 36. On the opposite side, the side wall 36 is pierced by at least one, here two outlet channels 34 running radially outwards and terminating at a distance outside the side wall 36 in the cover plate 30.
Pump chamber 31, inlet basin 33 and both inlet and outlet channels 33′, 34 are enclosed by a fully circular second sealing groove 32.
Formed at one side edge of the cover plate 30 is a protruding nose, which forms a lower channel connector 37 with upright side walls. This lower channel connector 37 forms the counterpart to the upper channel connector 17 and thus preferably has a U-shaped longitudinal section. The abovementioned protruding nose 27 of the pump membrane 2 is of such a size that it corresponds to the base area of the channel connectors 17, 37 and is held therein.
Outside the second sealing groove 32 there are seat openings 35, 35′, 35″ which take up the positioning and fastening pins 15, 15′, 15″. These openings 35, 35′, 35″ are flush with the top side of the cover plate 30. On the underside of same, however, they are formed as uptake sockets and are connected to one another preferably via reinforcing ribs 38. The sockets also can be provided on the inside with vertical ribs or have positioning aids. The sockets preferably have an unround inner cross section and are preferably polygonal. This again increases the stability of the connection with the pins.
As is evident from FIG. 2, the underside of the cover plate 30 is designed structured as a negative to the elements formed in the top side of the cover plate. This means that the recesses of the top side are designed extending downwards on the underside and the elevations of the top side are correspondingly sunk in the underside. Here the cover plate 30 has a thickness approximately uniform over the entire base area or over a large part of the base area. This does not however apply at all points. By way of example, this does not apply in the area of the reinforcing links between the sockets or between other possible elevations in the underside. This type of structured cover plate can also be employed in suction pump units whose connecting elements connect the individual parts frictionally engaged or non-positively.
When the inventive unit is in the assembled state, the pump membrane 2 or its membrane plate 20 is now clamped in between the base plate 10 of the membrane frame 1 and the cover plate 30 of the membrane plate 3. At the same time the membrane piston 21 passes through the through hole 11 and because of the motor can move up and down. The membrane piston 21 covers the pump chamber 31 and, since the outer diameter of the membrane piston 21 is the same size as or greater than the outer diameter of the side wall 36 of the pump chamber 31, it seals the chamber 31 except for the inlet and outlet channels 33′, 34.
The fastening pins 15, 15′, 15″ pass through the fastening holes 25, 25′ of the pump membrane 2 and are plugged positively into the uptake sockets 35, 35′, 35″ of the membrane cover 3. In addition, they are stuck therein by means of adhesive or are connected otherwise to form a material or positive fit. By way of example, they can be ultrasound-welded, vibration-welded, welded at high frequency or ultrasound-riveted.
Due to this precise positioning of the three individual parts, the inlet opening 13 lies above the inlet valve flap 23 and the latter lies above the inlet basin 33. The outlet channel 14 of the membrane frame 1 lies above the outlet valve flaps 24 and the latter lie above the outlet channels 34 of the membrane cover.
The upper and lower sealing lips 22, 28 lie in the first and second sealing grooves 12, 32, respectively, and thus seal the areas in each case enclosed thereby to the exterior.
The side walls of the lower channel connector 37 resiliently enclose the side walls of the upper channel connector 17 and thus form a tight positive and frictional connection. The nose 27 of the pump membrane 2 lies on the lower channel connector 37.
The membrane piston 21 passes through the through hole 11 of the base plate 10 when the unit is in the assembled state.

LEGEND

- 1 membrane frame
- 10 base plate
- 10′ channel
- 10″ through hole
- 11 through hole
- 12 first sealing groove
- 13 inlet opening
- 13′ inlet channel
- 13″ connection channel
- 14 outlet channel
- 15 first fastening pin
- 15′ second fastening pin
- 15″ positioning pin
- 150 vertical ribs
- 151 hook
- 152 snap-in shackle
- 16 stop plate
- 17 upper channel connector
- 18 suction opening
- 18′ air intake
- 19 pump unit seat
- 2 pump membrane
- 20 membrane plate
- 21 membrane piston
- 22 upper sealing lip
- 23 inlet valve flap
- 24 outlet valve flap
- 25 first fastening hole
- 25′ second fastening hole
- 26 piston connector
- 27 nose
- 28 lower sealing lip
- 3 membrane cover
- 30 cover plate
- 31 pump chamber
- 32 second sealing groove
- 33 inlet basin
- 33′ inlet channel
- 34 outlet channel
- 35 first seat opening
- 35′ second seat opening
- 35″ positioning hole
- 36 side wall
- 37 lower channel connector
- 38 reinforcing rib
- 4 electromotor

Claims

1. Membrane suction pump unit with a dimensionally stable membrane frame, a dimensionally stable monobloc membrane cover, which has a pump chamber with a floor region and a side wall encircling the floor region and widening outwards away from the floor region, and with a monobloc pump membrane, which has a membrane plate, a flexible membrane piston, at least one inlet valve flap and at least one outlet valve flap, the membrane plate being arranged between the membrane frame and the membrane cover, and membrane frame, pump membrane and membrane cover being connected to one another by means of connecting elements in a preset position, the membrane piston passing through the membrane frame, and the membrane piston covering a pump chamber of the membrane cover, wherein there are more than three connecting elements and in that they form a material and/or positive fit.

2. Suction pump unit according to claim 1, in which the connecting elements are plugged into seat openings of the membrane frame and/or the membrane plate and are welded, riveted or bonded to the membrane frame or the membrane plate.

3. Suction pump unit according to claim 1, in which there are six to twelve, preferably nine connecting elements.

4. Suction pump unit according to claim 1, in which the connecting elements pass through the pump membrane exclusively in its outer edge region.

5. Suction pump unit according to claim 1, in which the membrane cover has a thickness which is uniform over approximately its entire surface.

6. Suction pump unit according to claim 1, in which the connecting elements are pins or snap-in elements.

7. Suction pump unit according to claim 1, in which at least some of the connecting elements are arranged on the membrane frame.

8. Suction pump unit according to claim 1, in which at least some of the connecting elements are arranged on the membrane cover.

9. Suction pump unit according to claim 1, in which membrane cover and membrane frame are made from plastic and the connecting elements are connected integrally to the membrane cover or the membrane frame.

10. Suction pump unit according to claim 1, in which at least some of the connecting elements are provided with longitudinal ribs.

11. Suction pump unit according to claim 1, in which at least some of the connecting elements are provided with a positioning aid.

12. Suction pump unit according to claim 1, in which the membrane cover and/or the membrane frame has socket-like seats for taking up the connecting elements.

13. Suction pump unit according to claim 12, in which the socket-like seats are interconnected by ribs.

14. Suction pump unit according to claim 12, in which the seats have an unround, in particular polygonal, cross-section.

15. Suction pump unit according to claim 1, in which the membrane plate has inlet and outlet valve flaps and on one side has a first sealing lip, the sealing lip completely encircles the membrane piston, the inlet and outlet valve flaps are located inside a region enclosed by the sealing lip, and the connecting elements pass through the membrane plate outside this circular sealing lip.

16. Suction pump unit according to claim 15, in which the membrane plate has, on the opposite side, a second sealing lip which cooperates with the first sealing lip and likewise encloses the membrane piston and the inlet and outlet valve flaps.

17. Suction pump unit according to claim 16, in which the first and second sealing lips are congruent.

18. Suction pump unit according to claim 1, in which the pump membrane is designed in one piece from a flexible material.

19. Membrane suction pump unit with a dimensionally stable membrane frame, a dimensionally stable monobloc membrane cover, which has a pump chamber with a floor region and a side wall encircling the floor region and widening outwards away from the floor region, and with a monobloc pump membrane, which has a membrane plate, a flexible membrane piston, at least one inlet valve flap and at least one outlet valve flap, the membrane plate being arranged between the membrane frame and the membrane cover, and membrane frame, pump membrane and membrane cover being connected to one another by means of connecting elements in a preset position, the membrane piston passing through the membrane frame, and the membrane piston covering a pump chamber of the membrane cover, characterized in that there are more than three connecting elements.

20. Membrane suction pump unit with a dimensionally stable membrane frame, a dimensionally stable monobloc membrane cover, which has a pump chamber with a floor region and a side wall encircling the floor region and widening outwards away from the floor region, and with a monobloc pump membrane, which has a membrane plate, a flexible membrane piston, at least one inlet valve flap and at least one outlet valve flap, the membrane plate being arranged between the membrane frame and the membrane cover, and membrane frame, pump membrane and membrane cover being connected to one another by means of connecting elements in a preset position, the membrane piston passing through the membrane frame, and the membrane piston covering a pump chamber of the membrane cover, characterized in that the connecting elements form a material and/or positive fit.

21. Membrane suction pump unit with a dimensionally stable membrane frame, a dimensionally stable monobloc membrane cover, which has a pump chamber with a floor region and a side wall encircling the floor region and widening outwards away from the floor region, and with a monobloc pump membrane, which has a membrane plate, a flexible membrane piston, at least one inlet valve flap and at least one outlet valve flap, the membrane plate being arranged between the membrane frame and the membrane cover, and membrane frame, pump membrane and membrane cover being connected to one another by means of connecting elements in a preset position, the membrane piston passing through the membrane frame, and the membrane piston covering a pump chamber of the membrane cover, characterized in that the membrane cover has a thickness which is uniform over approximately its entire surface.

22. Suction pump unit according to claim 21, in which the membrane cover has an underside which faces away from the pump membrane and which is designed structured.