Title:
Mechanical liquid pump
Kind Code:
A1


Abstract:
A mechanically operated liquid pump for medical and nutrient liquids, as well as for liquids used in biological and laboratory applications, has an integrated, self-contained pump construction comprising a housing having an expandable elastic member mounted wholly within the housing and shaped to store and dispense a liquid therefrom. Inlet and outlet members are also mounted within the housing, are operably connected with the elastic member inside the housing, and regulate the flow of liquid traveling into and out of the pump. A flow regulator is also mounted wholly within the housing, communicates with at least one of the inlet and outlet members, and maintains a substantially constant volumetric flow of liquid dispensed from the elastic member.



Inventors:
Wex, Roland (Melsungen, DE)
Hansmann, Harald (Wismar, DE)
Kenzler, Christian (Pritzwalk, DE)
Application Number:
11/989255
Publication Date:
08/27/2009
Filing Date:
07/21/2006
Primary Class:
International Classes:
F04B43/08
View Patent Images:
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Primary Examiner:
EISENBERG, REBECCA E
Attorney, Agent or Firm:
PRICE HENEVELD LLP (695 KENMOOR SE P O BOX 2567, GRAND RAPIDS, MI, 49501, US)
Claims:
1. 1-17. (canceled)

18. In a mechanically operated liquid pump for medical and nutrient liquids, as well as for liquids used in biological and laboratory applications and the like, the improvement comprising an integrated, self-contained pump construction, comprising: a housing member; an expandable elastic member mounted wholly within said housing member, and shaped to store and dispense a liquid therefrom; a closeable inlet member mounted within said housing member, operably connected with said elastic member at a location inside said housing member and regulating the flow of liquid traveling into said elastic member; an outlet member mounted within said housing member, operably connected with said elastic member at a location within said housing member and routing the liquid traveling out of said elastic member; and a flow regulator member mounted wholly within said housing member, communicating with one of said inlet member and said outlet member, and maintaining a substantially constant volumetric flow of the liquid dispensed from said elastic member.

19. A pump as set forth in claim 18, wherein: said elastic member, said inlet member, said outlet member and said flow regulator member are each calibrated to ensure substantially constant volumetric flow of the liquid.

20. A pump as set forth in claim 19, wherein: said housing member has a sealed construction, such that at least said inlet member, said outlet member and said flow regulator member cannot be removed from said housing member without destroying said pump.

21. A pump as set forth in claim 20, wherein: said inlet member comprises one of either a Luer lock valve or a Luer lock attachment; and said outlet member comprises the other of said Luer lock valve and said Luer lock attachment.

22. A pump as set forth in claim 21, including: a core member mounted in said housing member and including a channel therethrough for delivery and dispensing of the liquid into and out of said elastic member; and wherein said elastic member comprises a balloon having an open end portion thereof sealingly mounted on said core.

23. A pump as set forth in claim 22, wherein: said flow regulator member comprises a pressure control valve.

24. A pump as set forth in claim 22, wherein: said flow regulator member comprises a glass capillary or meander chip.

25. A pump as set forth in claim 24, including: a filter member mounted within said housing member and disposed upstream of said flow regulator member.

26. A pump as set forth in claim 25, wherein: said housing member includes a middle portion, an upper portion and a lower portion.

27. A pump as set forth in claim 26, wherein: said housing member includes a cap detachably connected with said upper and lower portions of said housing member, and enclosing said balloon and said core therein.

28. A pump as set forth in claim 27, wherein: at least one of said core, said balloon, said outlet member, said filter member and said flow regulator member has at least a portion thereof mounted in said middle portion of said housing member.

29. A pump as set forth in claim 28, wherein: at least one of said core, said balloon, said outlet member, said filter member and said flow regulator member is mounted between said middle portion and a said upper portion of said housing member.

30. A pump as set forth in claim 28, wherein: at least one of said core, said balloon, said outlet member, said filter member and said regulator member is mounted between said middle portion and said lower portion of said housing member.

31. A pump as set forth in claim 28, including: a bolus member mounted within said middle portion of said housing member.

32. A pump as set forth in claim 28, wherein: said inlet member is mounted in either said upper portion or said lower portion of said housing member.

33. A pump as set forth in claim 28, wherein: said upper portion of said housing member covers an upper side of said middle portion of said housing member, and said lower portion of said housing covers a lower side of said middle portion of said housing member.

34. A pump as set forth in claim 33, wherein: said housing member is constructed of plastic; and said upper portion, said middle portion and said lower portion of said housing members are fixedly interconnected by laser welding.

35. A pump as set forth in claim 34, wherein: said middle portion of said housing member includes embossed channels therein.

36. A pump as set forth in claim 35, wherein: said housing member has a generally flat shape.

37. A pump as set forth in claim 18, wherein: said housing member has a sealed construction, such that at least said inlet member, said outlet member and said flow regulator member cannot be removed from said housing member without destroying said pump.

38. A pump as set forth in claim 18, wherein: said inlet member comprises one of either a Luer lock valve or a Luer lock attachment; and said outlet member comprises the other of said Luer lock valve and said Luer lock attachment.

39. A pump as set forth in claim 18, including: a core member mounted in said housing member and including a channel therethrough for delivery and dispensing of the liquid into and out of said elastic member; and wherein said elastic member comprises a balloon having an open end portion thereof sealingly mounted on said core.

40. A pump as set forth in claim 18, wherein: said flow regulator member comprises a pressure control valve.

41. A pump as set forth in claim 18, wherein: said flow regulator member comprises a glass capillary or meander chip.

42. A pump as set forth in claim 18, including: a filter member mounted within said housing member and disposed upstream of said flow regulator member.

43. A pump as set forth in claim 18, wherein: said housing member includes a middle portion, an upper portion and a lower portion.

44. A pump as set forth in claim 43, wherein: at least one of said core, said balloon, said outlet member, said filter member and said flow regulator member has at least a portion thereof mounted in said middle portion of said housing member.

45. A pump as set forth in claim 44, wherein: at least one of said core, said balloon, said outlet member, said filter member and said flow regulator member is mounted between said middle portion and a said upper portion of said housing member.

46. A pump as set forth in claim 44, wherein: at least one of said core, said balloon, said outlet member, said filter member and said regulator member is mounted between said middle portion and said lower portion of said housing member.

47. A pump as set forth in claim 18, wherein: said housing member includes a cap detachably connected with said housing member, and enclosing said balloon and said core therein.

48. A pump as set forth in claim 18, including: a bolus member mounted within said housing member.

49. A pump as set forth in claim 18, wherein: said housing member is constructed of plastic; and said housing member includes upper, middle and lower portions which are fixedly interconnected by laser welding.

50. A pump as set forth in claim 18, wherein: said housing member includes a middle portion with embossed channels formed therein.

51. A pump as set forth in claim 18, wherein: said housing member has a generally flat shape.

Description:

FIELD OF THE INVENTION

The invention relates to a mechanically operated liquid pump, particularly for medical or nutrient liquids, and for liquids in the biological and laboratory sector.

BACKGROUND OF THE INVENTION

Many different types of liquid pumps are used for delivering medical, nutrient or biological liquids, or liquids in the laboratory sector. For example, pumps are known that are operated by electric energy, electrochemically, by gas, mechanically, electromechanically, and by physical mechanics. Many of these pumps can generally only be used after quite a long start-up time and often provide the user and consumer with insufficient dosing precision. The known pump systems are also very expensive and are not very satisfactory from the environmental point of view. They often cannot be used portably by the user.

Mechanically operated liquid pumps are characterized by a drive mechanism, which can generally be of quite simple configuration. Thus, various designs have been disclosed in which expandable elastic elements are used to store and dispense the liquid.

A mechanically operated liquid pump, particularly for medical or nutrient liquids, is known from EP 0 944 405 B1. It has a housing designed as a tube. The housing accommodates an expandable elastic element that is used to store and dispense the liquid and that is designed as a hose. The latter has openings in the area of its ends. A conduit for delivering liquid to the hose is connected to the hose in the area of one opening. A further conduit that serves to discharge the liquid out of the hose is connected to the latter in the area of the other opening. This conduit is routed out of the housing. The end of the conduit directed away from the hose is provided with a device for restricting the volumetric flow of liquid dispensed from the elastic element.

A mechanically operated liquid pump, particularly for medical and nutrient liquids, is known from DE 100 58 121 A1. It comprises a bag for receiving the liquid, and a dispensing conduit for the liquid. The bag is placed into a housing. The housing has a first housing part with hinges at both ends for receiving a second housing part and also a closure lid for the second housing part. Both housing parts are assigned a device for exerting a compressive force on the bag for the purpose of dispensing the liquid from the latter. This device comprises an elastic element for acting on one side of the bag, and the second housing part for acting on the opposite side of the bag. The bag used in the pump, or the pump itself, can be used just once or can be reused several times. Depending on the chosen elasticity of the elastic element, different flow rates and emptying times are possible for the pump. The elastic element is designed such that the liquid is pressed out of the bag until the elastic element bears on the second housing part for acting on the opposite side of the bag, and the bag is emptied in this state.

EP 1 321 156 A1 describes a valve, particularly for medical and nutrient liquids. This valve allows the flow of liquid passing through the valve to be kept substantially constant. A component part of the valve is formed by a valve body that has the function of an active regulating element, the function of which depends on the liquid pressure acting in a chamber of the valve. If the pressure in the liquid chamber increases, this leads to an adjustment movement of the valve body, which movement throttles the discharge of the liquid from the inlet channel of the valve, whereas a decrease of the liquid pressure in the chamber has the effect that the valve body executes a movement that reduces the throttling of the liquid emerging from the inlet channel. A flow restrictor is fitted in the outflow parts of the valve. By choosing different flow restrictors, and replacing one flow restrictor with another flow restrictor, it is possible to set various constant flow rates of the valve.

EP 0 424 494 B1 describes a device for dispensing a fluid to an outlet, the fluid being in particular a medical liquid. This liquid is delivered to a hose from an expandable elastic element for storing and dispensing the liquid, which hose establishes the connection to a cannula on the patient side. The hose is assigned a device for restricting the volumetric flow of liquid dispensed from the elastic element. This conduit forms the main conduit. A side conduit branches off upstream of the restrictor device and opens back into the main conduit downstream of the restrictor device. The side conduit is provided with a bolus dose device.

A common feature of all the devices mentioned above is that they have only some of the functional parts necessary for a mechanically operated liquid pump. This means that they have to be combined with other required functional parts. This combination is provided in the form of separate units, which accordingly have to be connected to one another for use. This means complicated handling, especially if medical or nutrient liquids are to be administered, and, in addition, there is considerable danger of the functional parts being mixed up or incorrectly connected. There is therefore a considerable danger of incorrect operation of a system made up of individual functional parts and intended to function as a mechanically operated liquid pump.

SUMMARY OF THE INVENTION

The object of the present invention is to make available a mechanically operated liquid pump, particularly for medical or nutrient liquids, in which all the functional parts required for the function of the liquid pump are accommodated in one unit that is of a particularly compact design, this arrangement of the functional parts being intended to ensure that incorrect operation of the pump is ruled out and, accordingly, when the pump is used in the field of medicine, that it simply has to be connected to the patient.

The object is achieved by a mechanically operated liquid pump, particularly for medical or nutrient liquids, and for liquids in the biological and laboratory sector, with the following functional parts mounted inside a housing of the liquid pump:

    • a closeable inlet for delivery of the liquid,
    • an expandable elastic element for storing and dispensing the liquid delivered via the closeable inlet,
    • a device for maintaining substantially constant and/or restricting the volumetric flow of liquid dispensed from the elastic element,
    • an outlet leading out of the housing.

Therefore, according to the invention, all the functional parts important for the function of the liquid pump are arranged inside the housing of the liquid pump. Accordingly, to start the liquid pump up, all that need be done is to deliver the liquid through the closeable inlet and connect the outlet from the housing to the element that further conveys the liquid dispensed from the pump, for example via a Luer lock attachment to a hose, the end of which directed away from the attachment is connected to a catheter, which can be connected to the patient. The outlet is therefore provided in this case for connection to a device that can be connected to the patient.

It will therefore be appreciated that the liquid pump is simple to operate. Incorrect operation is ruled out, and, in the case of the pump being used in the field of medicine, all that has to be done is to connect the patient. By virtue of the configuration of the liquid pump according to the invention, with the functional parts mounted inside the housing, it is possible for the pump to have a small and compact design.

It is considered particularly advantageous if the functional parts are calibrated. The functional parts are thus adapted to one another in terms of their physical behavior, such that a substantially constant volumetric flow of liquid is dispensed from the pump, independently of the pressure in the expandable elastic element.

Advantageously, the housing, at least in an area having the inlet, the outlet and the device for maintaining substantially constant and/or restricting the volumetric flow of liquid dispensed from the elastic element, cannot be dismantled without destroying it, and, in particular, the entire housing cannot be dismantled without destroying it. Accordingly, if the housing is intact, i.e. not destroyed, as a whole or in the area of the aforementioned functional parts, this provides the person using the pump with an assurance that the pump has not been tampered with.

The inlet and/or the outlet are preferably designed as Luer lock valve or Luer lock attachment. These are therefore standardized valves and attachments, which permit uncomplicated delivery and discharge of the liquid.

According to a preferred embodiment of the invention, the expandable elastic element is designed as a balloon provided with an opening, the balloon being mounted sealingly in a core mounted in the housing, and at least one channel for delivery and dispensing of the liquid into the balloon and from the balloon extends through the core. It is therefore an elastic element provided with a single opening, in contrast to a hose with two openings. Accordingly, this opening serves both as an inlet for the liquid and also as an outlet for the liquid. The balloon preferably bears in a relatively unstressed state on the core. This is to be understood as meaning that the balloon can bear with a certain pretensioning on the core, since complete emptying of the balloon is to be sought. The balloon is fastened and sealed exclusively in the area of its end that has the opening. This is preferably done directly on the core. The balloon can in principle be made of any material having the necessary elasticity for storing and dispensing the liquid. Silicone is regarded as the preferred material. The balloon is intended to have a capacity of 10 ml to 150 ml in particular.

In the liquid pump, it is considered particularly important for it to have a relatively flat design, since it is generally worn by a patient directly on the body. To achieve an expansion of the balloon preferably in its direction of width and less so in the direction of its height, provision is made that, in a first direction of extent perpendicular to the longitudinal axis of the core, the balloon has relatively thick wall portions, and, in a second direction of extent perpendicular to the longitudinal axis of the core and perpendicular to the first direction of extent, it has relatively thin wall portions. This means that the balloon deforms more strongly in the area of the thin wall portions, with the result that, upon expansion of the element, a cross-sectional configuration approximating substantially to the shape of an ellipse is obtained. The balloon is produced in particular by injection molding.

According to a preferred embodiment of the invention, provision is further made that the device for restricting the volumetric flow of liquid dispensed from the elastic element is designed as a valve, in particular as a pressure control valve. The device for maintaining substantially constant the volumetric flow of liquid dispensed from the elastic element is preferably designed as a flow restrictor, in particular as a glass capillary or meander chip. A filter element for the liquid is arranged inside the housing, in particular upstream of the device for maintaining substantially constant the volumetric flow of liquid dispensed from the elastic element.

The housing is advantageously made up of several parts. It has in particular a middle part, an upper part and a lower part, the terms upper part and lower part having been chosen simply to distinguish these two parts relative to the middle part. Since the pump can be oriented in any desired way, the upper part can be the lower part and the lower part the upper part.

In view of the fact that the housing is made up of several parts, it is possible to assign defined functions to the individual parts of the housing and to the planes dividing the individual parts of the housing, for example the space between middle part and upper part. Thus, the housing preferably has a cap which can be connected to the upper part and to the lower part, in particular clipped non-releasably thereto, for arrangement of the balloon and of the core inside the cap. The core for the balloon and/or the outlet and/or the filter element and/or the device for restricting the volumetric flow of liquid dispensed from the elastic element is/are mounted in the middle part and in the upper part or lower part, between the middle part and the upper part or lower part. The device for restricting the volumetric flow of liquid dispensed from the elastic element and/or a bolus device is advantageously mounted in the middle part. The inlet is preferably mounted in the upper part or lower part. In order to cover the functional parts which, in the direction away from the middle part, can protrude past the upper part and/or lower part, a housing upper part is provided for covering the upper part, and a housing lower part is provided for covering the lower part.

The individual parts of the housing are preferably made of plastic. This allows the parts to be produced in virtually any desired shape, inexpensively and with low weight. Parts are connected to one another in particular by laser welding.

A particular function is played by the middle part of the housing. Thus, said middle part not only serves to receive functional parts, but also has the flow connections between the functional parts, said connections being formed in particular as channels embossed in the middle part. These channels are covered by connecting the middle part to the upper part and lower part, and a leaktight sealing of the channels between middle part and upper part or lower part is achieved in particular by laser welding.

As has been mentioned above, a particularly important aspect of the pump is considered to be that said pump or the housing is designed relatively flat. In the area of the balloon, this is achieved by the special configuration of the balloon and by the design of the housing as a cap. The rest of the housing is also designed flat and accommodates the functional parts arranged therein adjacent to one another, on different planes, on the one hand in the area of middle part and upper part and on the other hand in the area of middle part and lower part.

The mechanically operated liquid pump according to the invention thus integrates all the functional parts needed for perfect functioning of the liquid pump and is therefore advantageous in the following respects:

    • an integrated solution through omission of an external hose system between pump, volumetric flow restrictor and optionally present bolus reservoir,
    • an integrated system for delivery of liquid to the individual components through channels embossed in the middle part,
    • an integrated pump solution using a balloon that interacts with a core,
    • an integrated capillary/meander protection filter,
    • an integrated volumetric flow restrictor in the form of a capillary or meander chip,
    • an optional bolus solution, which can be arranged in series or as bypass,
    • an integrated automatic pressure control valve for constant flow rate.

Further features of the invention are set forth in the dependent claims, in the description of the figures, and in the figures themselves. It will be noted that all the individual features and all combinations of the individual features are part of the invention.

The invention is depicted in the figures on the basis of a mechanically operated liquid pump that is provided with the valve, without being limited to this illustrative embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of a mechanically operated liquid pump using the valve according to the invention,

FIG. 2 shows a vertical longitudinal midsection through the pump shown in FIG. 1, in particular to illustrate the drive mechanism of the pump, with a balloon bearing on a core,

FIG. 3 shows a section according to FIG. 2, with the balloon filled with liquid,

FIG. 4 shows a vertical longitudinal section through the pump shown in FIG. 1, at a distance from the longitudinal center axis of the pump, in the area of a valve of the pump,

FIG. 5 shows a section, cut transversely through the pump illustrated in FIG. 1, in the area of the valve,

FIG. 6 shows a horizontal longitudinal midsection through the pump shown in FIG. 1, with the balloon bearing on the core,

FIG. 7 shows a section according to FIG. 6, with the balloon filled with liquid,

FIG. 8 shows a section through the pump, cut transversely in the area where the core is supported,

FIG. 9 shows a section through the pump, cut transversely in the area of the unsupported portion of the core and of the liquid-filled balloon,

FIG. 10 shows an enlarged sectional view of core, balloon and clamping ring for connection of balloon and core, with the balloon bearing on the core,

FIG. 11 shows a section, cut transversely to the longitudinal extent of the core, through the core and the balloon, with the balloon bearing on the core,

FIG. 12 shows a sectional view according to FIG. 11 for a modified cross-sectional configuration of the balloon,

FIG. 13 shows an enlarged sectional view of the valve shown in FIG. 4,

FIG. 14 shows a diagram illustrating the operating principle of the mechanically operated liquid pump, and indicating physical parameters,

FIG. 15 shows a diagram illustrating the basic arrangement of the bolus implementation that can be used in the pump, in a serial circuit,

FIG. 16 shows a diagram according to FIG. 15 for arrangement of the bolus implementation in a bypass circuit, and

FIG. 17 shows a cross-sectional view of bolus implementation used in a pump according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of description herein, the terms “upper”, “lower”, “right”, “left”, “rear”, “front”, “vertical”, “horizontal” and derivatives thereof shall relate to the invention as oriented in FIG. 1. However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

The mechanically operated liquid pump 1 illustrated in FIG. 1 is used in particular for administering medical or nutrient liquids, for example for administering a liquid medicament.

The pump 1 has a multi-component housing 2 formed by a middle part 3, by an upper part 4 and a lower part 5 that interact with said middle part 3, by an upper shell 6 interacting with the upper part, and by a lower shell 7 interacting with the lower part 5.

The middle part 3 is provided on its upper face with a recess 8 that is open to the free edge of the middle part 3 and that has a semicircular cross section, and the upper part 4 is provided on its lower face, and in the corresponding edge area, with a corresponding semicircular recess 9. With the upper part 4 connected to the middle part 3, the two recesses 8 and 9 form a circular cross section for receiving a conically widened end area 10 of a core 11. Except at its end area 10, the core 11 has a constant external diameter. This cylindrical portion of the core 11 is designated by reference number 12. A channel 13 (see FIG. 2) extends through the core 11 in its longitudinal center axis, and several channels 14 extending radially through the core 11 branch off from the channel 13 in the area of the portion 12 (FIG. 6). In the area of the outer circumference of the core 10, the radial channels 14 open into circumferential grooves 15 of the core 11.

An elastic element interacts with the core 11 and is designed as a silicone balloon 16. The latter is produced by injection molding. The balloon has a conically widened end area 17 with opening 17a, corresponding to the end area 10 of the core 11, and it has a portion 18 which corresponds to the outer shape of the portion 12 of the core 11 and which merges into the end area 19, closed on account of the balloon design and remote from the end area 17.

The dimensions of core 11 and balloon 16 are such that, as can be seen from FIG. 2, the balloon fitted onto the core 11 bears completely on the core 11, such that the end area 17 of the balloon contacts the end area 10 of the core, and the portion 18 of the balloon 16 contacts the portion 12 of the core 11, and, finally, the end area 19 of the balloon 16 bears on the free end of the core 11. The dimensions of the balloon 16 in relation to the core 11 are chosen here such that the balloon 16 bears on the core 11 with relatively little pretensioning, in other words in a relatively unstressed state.

In order to fasten the end area 17 of the balloon 16 on the core 11, at the end area 10 of the latter, a clamping ring 20 is provided, which is fitted externally onto the balloon 16 at the end area 17 thereof. The structure thus formed is inserted with the clamping ring 20 into the recess 8 of the middle part 3, and the upper part 4 is then connected to the middle part 3, as a result of which the clamping ring 20 and therefore the core 11 and balloon 16 are held secure in the recesses 8 and 9 of middle part 3 and upper part 4. For the clamping ring 20, the recesses 8 and 9 have a seat that widens conically in the direction away from the respective free edge of the middle part 3 and upper part 4, in order to ensure a secure hold of the clamping ring 20.

The middle part 3, the upper part 4 and the lower part 5 serve to receive further operating elements of the pump 1:

A Luer check valve or lock valve 21 connected to the upper part 4 passes through an opening 22 in the upper part 4, and, as is explained in the following description of FIG. 2, has a Luer lock valve housing 23 and a Luer lock valve core 24. By way of a channel 25, the Luer lock valve 21 is in communication with a channel 26, which is formed between the upper part 4 and the middle part 3 and which communicates with the channel 13 extending through the core 11.

The pump is filled with liquid by way of the Luer lock valve 21 and the channels 25, 26 and 13. Starting from the unfilled state shown in FIG. 2, and with increasing delivery of liquid, the balloon 16 expands in that area not clamped by the clamping ring 20, and, when completely filled, adopts the final shape illustrated in FIG. 3. The space occupied by the liquid is designated there by reference number 27. It will be seen from FIGS. 2, 3 and 6 to 12 that, as it fills with liquid, starting from its initial state bearing on the core 11, the balloon 16 changes shape both in the longitudinal direction of the core and also in transverse directions thereof, i.e. in a first transverse direction and in a second transverse direction perpendicular thereto.

The upper part 4 and the lower part 5 are provided with locking projections 28, which serve to receive a cap 29 that is approximately kidney-shaped in cross section. As can be seen from FIG. 9, this cap has an extension in its direction of width that is substantially greater than that in the direction of its height. The width to height ratio is 2:1, for example. As can be seen from FIG. 2 for example, the length to height ratio of the cap 29 is approximately 2.5:1. The cap 29 is preferably clipped non-releasably onto the housing 2. When the balloon 16 is filled completely with liquid, it takes up as much as possible of the internal space in the cap 29.

This is achieved by the fact that, as can be seen from the view in FIG. 11 showing the balloon 16 bearing on the core 11, the balloon 16 has relatively thick wall portions 30 in a first direction of extent X perpendicular to the longitudinal axis of the core 11, and it has relatively thin wall portions 31 in a second direction of extent Y perpendicular to the longitudinal axis of the core 11 and perpendicular to the first direction of extent X. Thus, when liquid is introduced into its space 27, the balloon 16 seeks to expand preferably in the direction of extent X, thereby resulting in the expanded oval cross-sectional shape illustrated in the view in FIG. 9. Overall, the pump 1 is presented as a flat functional component that can be easily worn on the body, and the balloon 16, in the state when filled with liquid, likewise adopts a flat shape adapted to the outer contour of the pump 1.

The channels 26 and 13 serve not only to deliver the liquid from the Luer lock valve 21 into the balloon 16, but also to dispense the liquid from the interior of the balloon 16 to the patient. Thus, the channel 26 is continued past the inlet point of the channel 25 to a valve 32 that is mounted in the middle part 3 and upper part 4 and that restricts the volumetric flow of liquid discharged from the balloon 16. This valve 32 is formed by an elastic valve membrane 33 held at the edge between middle part 3 and upper part 4, by a valve core 34 that interacts with the valve membrane 33, by a compression spring 35 supported on the valve membrane 33 and the upper part 4, and by an adjusting screw 36, which is mounted in a thread of the upper part 4 and can be brought into operative connection with the valve membrane 33.

As can be seen from the detailed view in FIG. 13, the channel 26 opens into a radially extending channel 37 of the valve membrane 33 and from there into a radial channel 38 of the valve body 34, which opens into an axial channel 39 of the valve core 34. This channel 39 is open in the area of its end directed toward a reinforced portion 40 of the valve membrane 33. A stop designed as an adjusting screw 36 is arranged on that side of the portion 40 directed away from the channel 39, which portion 40 has the function of a closure element. In principle, this stop could also be stationary. Between the projections 41 of the valve membrane 33, the valve core 34 is held so as to be axially immovable relative to the valve membrane 33 and also non-rotatable relative to the latter.

The valve 32 is used to stop the volumetric flow in the event of too high a pressure. Two separate chambers 42 and 43 are formed in the valve and are connected to each other via a channel 44, which extends through the valve core 34 and is arranged parallel to the channel 40. The chamber 42, which lies in the direction of flow to the inlet, and therefore to the channel 26, serves as a blocking chamber. The chamber 43 lies in the direction of flow to the outlet 45. To filter the liquid dispensed through the valve 32, a filter 46 is provided which is clamped at the edge between the middle part 3 and the lower part 5. Starting from the chamber 43 and the outlet 45, the liquid passes to a channel 47 (FIG. 5) in flow communication with the outlet 45, and from there to a Luer lock attachment 48 held between the middle part 3 and the lower part 5. A Luer lock connector 49, provided with a hose 50 leading to the patient, can be connected to the Luer lock attachment 48.

As can be seen from the view in FIG. 5, a glass capillary 53 is fitted into the channel 47. This glass capillary constitutes a flow restrictor, which is able to restrict the volumetric flow passing through the channel 47 out of the pump, since the flow restrictor has a smaller cross section than the channel 37 lying in the inlet. By selecting various flow restrictors, it is possible to set various constant flow rates, as long as the pressure at the inlet does not drop below a defined value. In principle, the cross-sectional area of flow of the inlet is greater than the cross-sectional area of flow of the outlet. Of course, the flow restrictor can be designed other than in the form of a glass capillary. For example, it is entirely conceivable to provide downstream of the valve, in the outlet of the pump, a meander chip that restricts the through-flow.

Because of the stated diameters of the channels that connect the space 27 of the balloon to the valve 32, and the diameter of the channels arranged behind the valve 32 with the flow restrictor 53, the resistance that the channel 47 with flow restrictor 53 sets against the outflow of liquid from the housing 2 is greater than the resistance made to the liquid flowing into the valve 32.

In an initial state, the valve membrane 33 is located in the position shown in FIG. 13, in which the valve membrane 33 bears largely on the middle part 33, without requiring any action of the compression spring 35. Because of the positioning of the valve core 34 relative to the portion 40 of the valve membrane 33, a small gap is provided between the portion 40 and an encircling and therefore annular projection 54 of the valve core 34. This projection 54 encloses the channel 43. Accordingly, liquid flows through the channel 13 of the core 11 and through the adjoining housing channel 26 into the channel 37 of the valve membrane 33 and from there into the channels 38 and 39 of the valve core 34. From the channel 39 of the valve core 34, the liquid flows through the gap formed between the projection 54 and the portion 40 of the valve membrane 33, and into the chamber 42 located there, and from the chamber 42 through the channel 44 between valve membrane 33 and valve core 34 to the chamber 43, passes the filter 46 and travels through the outlet 45 to the channel 47 with the flow restrictor 53. If a higher liquid pressure is established in the inlet, thus also in the channel 39, without a greater volumetric flow being able to issue from the pump as a result of the flow restrictor 43, this has the result that the valve membrane 33, which is clamped in the edge area between the middle part 3 and the upper part 4, deforms in the central area in the direction of the adjusting screw 36 with the stop function, specifically counter to the force of the compression spring 35. When the valve membrane 34 with its portion 40 comes up against the projection 55 of the adjusting screw 36 directed toward the portion 40, the portion 40 makes contact there with the adjusting screw 36, such that, since the valve membrane 33 cannot move any farther up in the direction of the upper shell, the portion 40 is pressed against the projection 54 of the valve core 34 and thus closes the flow through the channel 39. As the liquid flows out through the flow restrictor 53, the pressure in the chamber 43 decreases, with the result that the membrane, by virtue of its own elasticity, moves back again in the direction of its initial state according to FIG. 13, such that the portion 40 disengages from its contact with the adjusting screw 36, and the flow gap between the projection 54 and the portion 40 is again freed. Depending on the pressure prevailing in the balloon 16, this state can be obtained only when the initial position of the valve membrane 33 is reached, as shown in FIG. 13, or even earlier, in other words with the valve membrane 33 still deflected. The adjusting screw 36 serves to modify the opening and closing behavior of the valve 32. The further the screw frees the adjustment path of the valve membrane, the greater is the secondary pressure in the valve. In principle, it is not necessary to provide the compression spring 35. It is of advantage when greater pressures are intended to be dealt with by the pump 1 and, accordingly, the elastic restoring behavior of the valve membrane 33 is not sufficient to move it into the initial position according to FIG. 13.

With the valve 32, the volumetric flow of liquid is therefore restricted as a function of the pressure prevailing in the balloon 16, and the volumetric flow of liquid is maintained substantially constant via the flow restrictor 53. In principle, the liquid pump could be modified by providing only a device for maintaining substantially constant the volumetric flow of liquid dispensed from the elastic element, or only a device for restricting the volumetric flow of liquid dispensed from the elastic element.

Before using the mechanically operated liquid pump, liquid is delivered through the Luer lock valve 21, as a result of which the liquid passes into the balloon 16, and the filling level of the balloon can be read off through the transparent cap 29 on the basis of the markings 51 which are arranged in the transverse direction of the cap and which are a reference for the transverse expansion of the balloon as a function of its state of filling. After the pump 1 has been filled and the pump has been attached to the patient via the hose 50, liquid is dispensed out of the pump through the valve 32, with elastic pretensioning of the expanded balloon 16, and this is done until the balloon has been completely emptied and bears on the core 11.

The particularly simple design of the described liquid pump allows it to be used in a variety of different ways. The user is able to operate the pump anywhere, and immediately, without long start-up times. It can be used carried around by the user, or used in one place, specifically in all normal life situations in or outside the field of medicine. The pump can be used in a sterile state and requires minimal operating/handling effort. Because of the simple construction of the small number of component parts, the pump is inexpensive to produce. This is a condition for its being able to be used particularly in outpatient care, and in financially weak markets. The low weight of the pump permits its use in accident and emergency situations, in field hospitals and in disaster areas. Some or all of the functional elements of the pump are exchangeable. The pump is suitable for short or long dispensing times, for example, in the case of a balloon with a capacity of 25 ml, for a flow rate of 2.5 ml per hour, that is to say a running time of 10 hours. It is of course possible to use other balloons with other volumes, for example 10 ml, 50 ml, 100 ml or 150 ml. The running time can be much longer, for example up to 24 hours. Although flow rates of >1000 ml per hour are entirely possible, a flow rate of 0.5 to 10 ml per hour is considered the preferred option.

According to the illustrative embodiment, a balloon is described which is produced by injection molding and serves as a container for the medicament solution and as a pressure reservoir. The balloon has a defined contour in cross section and in expansion, for filling flat housing spaces and for avoiding pressure peaks. It is radially and/or axially pretensioned on a one-part or multi-part core, in order to increase the restoring forces. One end of the balloon is sealed off in an airtight manner over the core and fixed in position by a clamping ring with a form fit. The balloon is freely movable in the axial and radial directions during filling and emptying, being elastically deformable and able to move in a manner free from friction inside the cap.

The pump 1 can additionally be provided with a bolus reservoir. In FIG. 1, the provision of such a bolus is indicated by reference number 52. The pump can be converted to this extent, as and when required.

FIG. 14 is a diagram illustrating how the above-described mechanically operated pump works and showing the physical parameters. The contour of the pump is indicated by the dot-and-dash line.

FIG. 15, relating to the bolus implementation, shows the bolus reservoir BR downstream of the capillary K, and thus downstream of the device for maintaining substantially constant the volumetric flow of liquid dispensed from the elastic element BK.

The conduit leading to the capillary K is designated by ZF, and the conduit leading away from the bolus reservoir is designated by AF. In contrast to the serial circuit of capillary K and bolus reservoir BR shown in FIG. 15, these are shown in a parallel circuit in FIG. 16.

FIG. 17 illustrates the configuration of the bolus reservoir in place of the bolus arrangement designated by reference number 52 in FIG. 1. In a serial circuit in the sense of the illustration in FIG. 15, the channel 47 downstream of the capillary 53 (FIG. 5) opens into a bolus chamber 56, which is designed as a depression in the lower part 5 and which is sealed off from a recess 58 in the middle part 3 by means of an elastic membrane 57 clamped between the middle part 3 and the lower part 5 in the edge area. The recess 58 serves to receive a ram 59, which is displaceable toward the membrane 57 in the direction of the arrow F counter to the restoring force of an elastic silicone ring 60, such that it moves the membrane 57 into the bolus chamber 56, as a result of which liquid abruptly issues from the bolus chamber 56 to the outlet of the pump and thus to the Luer lock attachment 48. As soon as there is no longer any pressure being exerted on the ram 59 from outside, the force of the elastic silicone ring 60 causes the ram 59 to return to its initial position shown in FIG. 17, in which the volume of the bolus chamber 56 is increased again and the ram 59 bears with a projection on the upper part 4 and also extends through a passage 61 in the upper part 4. Instead of the elastic silicone ring, it is also possible, for example, to provide a compression spring that surrounds the ram 59 and has the task of transferring the latter to its position freeing the bolus chamber 56, as is illustrated in FIG. 17.

Therefore, by means of the bolus device, a discrete administration of dosed individual quantities of medicament solutions is made possible.

In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise.

The invention claimed is as follows.