A drug dosage monitoring device and drug delivery system

Abstract

This application relates to a drug dosage monitoring device and a drug delivery system. The drug monitoring device includes: a drug reservoir with a drug storage chamber; a piston located within the drug storage chamber; a fixed electrode located outside the second end of the drug reservoir; multiple electrode plates located between the fixed electrode and the second end of the drug reservoir, with the multiple electrode plates and the fixed electrode arranged at intervals; a wire clamping device located on the side of the piston away from the first end of the drug reservoir; and a wire in contact with both the fixed electrode and the wire clamping device. The wire contacts at least one of the multiple electrode plates when the piston moves to different positions within the drug reservoir. The drug dosage monitoring device of this application can determine the position of the piston by detecting the continuity between the fixed electrode and each electrode plate. Based on the position of the piston, the amount of drug output from the drug reservoir in one piston movement and the remaining amount of drug in the drug reservoir can be determined.

Description

Technical Field

[0001] This application relates to the field of drug delivery technology, and in particular to drug dosage monitoring devices and drug delivery systems. Background Technology

[0002] Insulin therapy plays a crucial role in the treatment and management of diabetes. A primary method of insulin therapy is insulin infusion via an insulin pump. Insulin pumps typically carry a multi-day supply of insulin. During operation, it's essential to monitor the remaining insulin level to ensure sufficient supply for the next infusion and to promptly alert the user to the risk of insufficient remaining insulin. Due to the high integration and small size of insulin pumps, effective monitoring devices for accurate insulin level monitoring are currently lacking. Summary of the Invention

[0003] Therefore, it is necessary to address the above-mentioned problems by providing a drug dosage monitoring device and a drug delivery system.

[0004] In a first aspect, this application provides a drug dosage monitoring device, comprising:

[0005] A medicine storage device, wherein the medicine storage device has a medicine storage chamber, and the medicine storage device includes a first end and a second end opposite to each other; the first end of the medicine storage device is provided with a medicine outlet.

[0006] The piston is located inside the drug storage chamber;

[0007] A fixed electrode is located outside the second end of the drug reservoir and is spaced apart from the drug reservoir.

[0008] Multiple electrode plates are located between the fixed electrode and the second end of the drug reservoir, and the multiple electrode plates and the fixed electrode are arranged at intervals.

[0009] A wire-locking device is located on the side of the piston away from the first end of the medicine reservoir;

[0010] The wire is in contact with both the fixed electrode and the wire clamping device; when the piston moves to different positions within the drug reservoir, the wire is in contact with at least one of the multiple electrode plates.

[0011] In the drug dosage monitoring device of this application, by setting a fixed electrode, multiple electrode plates, a wire clamping device and a wire, when the piston in the drug reservoir moves to inject the drug, the wire moves with the piston. As the piston moves, the wire will come into contact with at least one of the multiple electrode plates. At this time, by detecting the continuity between the fixed electrode and each electrode plate, the position of the piston can be determined. Based on the position of the piston, the amount of drug output by the drug reservoir in one piston movement and the amount of drug remaining in the drug reservoir can be known.

[0012] In one embodiment, the drug dosage monitoring device further includes: a wire take-up and release device located outside the second end of the drug reservoir and arranged at intervals from the fixed electrode; one end of the wire is connected to the fixed electrode, and the other end is connected to the wire take-up and release device via the wire clamping device.

[0013] In one embodiment, the plurality of electrode sheets include:

[0014] The first electrode plate is located between the fixed electrode and the take-up and untake-up device; when the piston is in the initial position, the wire is in contact with the first electrode plate;

[0015] The second electrode plate is located between the fixed electrode and the second end of the drug reservoir;

[0016] The third electrode is located between the second electrode and the second end of the drug reservoir.

[0017] In one embodiment, the second end of the medicine reservoir is provided with an inlet.

[0018] In one embodiment, the dosage monitoring device further includes a pressure release device, the pressure release device comprising:

[0019] Release the pipeline and connect it to the inlet;

[0020] The switching valve structure is located on the release pipeline.

[0021] In one embodiment, the switching valve structure includes:

[0022] A ball valve is located on the release line;

[0023] A compression spring is fixed at one end and in contact with the ball valve at the other end.

[0024] In one embodiment, the dosage monitoring device further includes:

[0025] Multiple Hall elements are located on the outer wall of the medicine reservoir and are arranged at intervals along the length of the medicine reservoir;

[0026] A magnet is located on the piston.

[0027] In the above embodiments, by setting a first Hall element, a second Hall element, and a magnet, when the piston moves to output the drug from the storage container, the magnet will move with the piston. The first Hall element and the second Hall element can monitor the change in the magnetic field strength of the magnet, thereby accurately determining the position of the piston, and thus accurately knowing the amount of drug output by the storage container in one piston movement and the amount of drug remaining in the storage container.

[0028] Secondly, this application also provides a drug delivery system, the drug delivery system comprising:

[0029] As described in the first aspect, the drug dosage monitoring device has an inlet at the second end of the drug reservoir;

[0030] A membrane pump includes a metering tank and an elastic membrane; the elastic membrane covers the metering tank.

[0031] The first passage has one end connected to the drug outlet and the other end connected to the membrane pump, and extends above the elastic membrane;

[0032] The second passage is connected at one end to the membrane pump and extends above the elastic membrane;

[0033] The first switching valve is located in the first passage.

[0034] The second switching valve is located in the second passage;

[0035] A power source system, connected to the inlet and the metering tank, is used to inject driving fluid into the drug reservoir via the inlet to drive the piston to move, injecting the drug in the drug reservoir into the membrane pump and placing it in the metering tank; while injecting the drug into the membrane pump, the driving fluid in the metering tank is discharged; after the drug injection is completed, driving fluid is injected into the metering tank to discharge the drug in the membrane pump through the second passage.

[0036] The drug infusion system of this application allows for multiple infusions after a single drug injection, simplifying the treatment process.

[0037] In one embodiment, the power source system includes:

[0038] A power source for providing the driving fluid;

[0039] The third passage is connected at one end to the power source and at the other end to the inlet;

[0040] The fourth passage is connected at one end to the power source and at the other end to the metering pool;

[0041] The fifth pathway has one end connected to the quantitative cell;

[0042] The third switching valve is located in the fourth passage;

[0043] The fourth switching valve is located on the fifth passage;

[0044] The fifth switching valve is located on the third passage.

[0045] In one embodiment, the power source system includes:

[0046] A power source for providing the driving fluid;

[0047] The third passage is connected at one end to the power source and at the other end to the inlet;

[0048] The fourth passage is connected at one end to the power source and at the other end to the metering pool;

[0049] The fifth pathway has one end connected to the quantitative cell;

[0050] An air extraction device is connected to the end of the fifth passage that is furthest from the metering cell. Attached Figure Description

[0051] Figures 1 to 3 This is a schematic diagram of the structure of the dosage monitoring device provided in one embodiment of this application when the piston moves to different positions;

[0052] Figure 4 This is a schematic diagram of the drug dosage monitoring device provided in another embodiment of this application;

[0053] Figure 5 and Figure 6 This is a schematic diagram of the structure of the drug infusion system provided in different embodiments of this application.

[0054] Component labeling: 100, Drug reservoir; 101, Piston; 102, Fixed electrode; 103, First electrode plate; 104, Second electrode plate; 105, Third electrode plate; 106, Wire clamping device; 107, Wire; 108, Wire take-up and unwinding device; 109, First Hall element; 110, Second Hall element; 111, Magnet; 200, Membrane pump; 201, First passage; 202, Second passage; 203, First switching valve; 204, Second switching valve; 205, Power source; 206, Third passage; 207, Fourth passage; 208, Fifth passage; 209, Third switching valve; 210, Fourth switching valve; 211, Air extraction device. Detailed Implementation

[0055] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] In the description of this application, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the method or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0058] In one embodiment, see Figure 1 This application provides a drug dosage monitoring device, which may include: a drug reservoir 100, a piston 101, a fixed electrode 102, multiple electrode plates, a wire clamping device 106, and a wire 107; wherein, the drug reservoir 100 has a drug storage chamber (not shown), and the drug reservoir 100 includes opposing first ends (i.e., Figure 1 The right end of the medicine storage device 100 and the second end (i.e. Figure 1 The left end of the medicine storage container 100; the first end of the medicine storage container 100 is provided with a medicine outlet (not shown); the piston 101 is located in the medicine storage chamber; the fixed electrode 102 is located outside the second end of the medicine storage container 100 and is spaced apart from the medicine storage container 100; multiple electrode plates are located between the fixed electrode 102 and the second end of the medicine storage container 100, and the multiple electrode plates and the fixed electrode 102 are arranged at intervals; the wire clamping device 106 is located on the side of the piston 101 away from the first end of the medicine storage container 100; the wire 107 is in contact with both the fixed electrode 102 and the wire clamping device 106; the wire 107 is in contact with at least one of the multiple electrode plates when the piston 101 moves to different positions in the medicine storage container 100.

[0059] In the drug dosage monitoring device of this application, by setting a fixed electrode 102, multiple electrode plates, a wire clamping device 106, and a wire 107, when the piston 101 in the drug reservoir 100 moves to infuse the drug, the wire 107 will move with the piston 101. As the piston 101 moves, the wire 107 will come into contact with at least one of the multiple electrode plates. At this time, by detecting the continuity between the fixed electrode 102 and each electrode plate, the position of the piston 101 can be determined. Based on the position of the piston 101, the amount of drug output by the drug reservoir 100 in one piston movement and the amount of drug remaining in the drug reservoir 100 can be known.

[0060] As an example, the wire-clamping device 106 may include, but is not limited to, a hook for hooking the wire 107 so that the wire 107 can move when the piston 101 moves within the reservoir 100.

[0061] As an example, please continue reading Figure 1 The drug dosage monitoring device may also include: a take-up and release device 108, which is located outside the second end of the drug storage device 100, and is arranged at intervals with the fixed electrode 102; one end of the wire 107 is connected to the fixed electrode 102, and the other end is connected to the take-up and release device 108 via the wire clamping device 106.

[0062] Specifically, the take-up and release device 108 can be used to take up and release the wire when the piston 101 moves within the medicine reservoir 100, so as to ensure that the wire 107 is always taut.

[0063] In one example, the plurality of electrode plates may include: a first electrode plate 103, a second electrode plate 104, and a third electrode plate 105; the first electrode plate 103 is located between the fixed electrode 102 and the take-up and untake-down device 108; when the piston 101 is in the initial position, the wire 108 is in contact with the first electrode plate 103; the second electrode plate 104 is located between the fixed electrode 102 and the second end of the drug reservoir 100; and the third electrode plate 105 is located between the second electrode plate 104 and the second end of the drug reservoir 100.

[0064] As an example, the fixed electrode 102, the first electrode plate 103, the second electrode plate 104 and the third electrode plate 105 are arranged at intervals between each other.

[0065] As an example, the top of the third electrode 105 may be higher than the top of the second electrode 104.

[0066] Specifically, when the piston 101 is in position A, the wire 107 is in contact with the first electrode plate 103, such as... Figure 1 As shown; as the piston 101 moves, when the piston 101 moves to position B, the wire 107 comes into contact with the second electrode plate 104, as... Figure 2 As described above, when the piston 101 continues to move to position C, the wire 107 comes into contact with the second electrode plate 104 and the third electrode plate 105, such as... Figure 3As shown above, when a detection device (e.g., a current detection device) detects that the fixed electrode 102 and the first electrode plate 103 form a current loop, it can be determined that the piston 101 is located at position A; when a detection device detects that the fixed electrode 102 and the second electrode 104 form a current loop, it can be determined that the piston 101 is located at position B; when a detection device detects that the fixed electrode 102 and both the second electrode plate 104 and the third electrode plate 105 form a current loop, or when a current loop is detected between the fixed electrode 102 and the third electrode plate 105, it can be determined that the piston 101 is located at position C.

[0067] It should be noted that the specific number of the multiple electrode pads is not limited to the three mentioned above. In other examples, the actual number of the multiple electrode pads can be set according to the number of drug positions to be detected. For example, the number of the multiple electrode pads can be two, four, five, six, seven, eight, nine, ten or even more.

[0068] As an example, the second end of the medicine reservoir 100 may also be provided with an inlet (not shown); a driving fluid (e.g., gas) can be injected into the medicine reservoir 100 through the inlet to drive the piston 101 to move within the medicine reservoir 100.

[0069] As an example, the dosage monitoring device may also include a pressure relief device (not shown), which may include a release line (not shown) and a switching valve structure (not shown); wherein the release line is connected to the inlet; and the switching valve structure is located on the release line. By providing the pressure relief device, when the driving fluid pressure between the piston 101 and the second end of the drug reservoir 100 is too high, some of the driving fluid pressure can be released through the pressure relief device to alleviate the pressure.

[0070] As an example, the switching valve structure may include: a ball valve and a compression spring; the ball valve is located on the release line; one end of the compression spring is fixed, and the other end is in contact with the ball valve. The ball valve acts as a pressure regulator, and the compression spring provides the closing pressure of the ball valve; when the pressure of the driving fluid between the piston 101 and the second end of the reservoir 100 exceeds the closing pressure of the ball valve, the ball valve opens, releasing the driving fluid and preventing excessive pressure.

[0071] For example, please refer to Figure 4 The drug dosage monitoring device may also include: a plurality of Hall elements located on the outer wall of the drug reservoir 100 and arranged at intervals along the length of the drug reservoir 100; and a magnet 111 located on the piston 101.

[0072] In the above embodiment, by setting multiple Hall elements arranged at intervals along the length direction of the drug reservoir 100, when the piston 101 moves the drug reservoir 100 to output the drug, the magnet 111 will move with the piston 101. The multiple Hall elements can monitor the change in the magnetic field strength of the magnet 111, thereby accurately determining the position of the piston 101, and thus accurately knowing the amount of drug output by the drug reservoir 100 in one piston movement and the amount of drug remaining in the drug reservoir 100.

[0073] As an example, the plurality of Hall elements may include a first Hall element 109 and a second Hall element 110; wherein, the first Hall element 109 is located on the outer wall of the medicine reservoir 100; the second Hall element 110 is located on the outer wall of the medicine reservoir 100, and the second Hall element 110 and the first Hall element 109 are arranged at intervals along the length of the medicine reservoir 100. Of course, in other examples, the specific number of the plurality of Hall elements is not limited to the two mentioned above, and can be set to three, four, five or even more, depending on actual needs.

[0074] In another embodiment, please refer to Figures 1 to 4 See Figure 5 This application also provides a drug delivery system, which may include: such as Figures 1 to 4 The drug dosage monitoring device, membrane pump 200, first passage 201, second passage 202, first switching valve 203, second switching valve 204, and power source system provided in any embodiment; wherein, the second end of the drug reservoir 100 is provided with an inlet; the membrane pump 200 may include a metering tank (not shown) and an elastic membrane (not shown); the elastic membrane covers the metering tank; one end of the first passage 201 is connected to the drug outlet, and the other end of the first passage 201 is connected to the membrane pump 200 and extends above the elastic membrane; one end of the second passage 202 is connected to the membrane pump 200 and extends above the elastic membrane. The first switching valve 203 is located on the first passage 201; the second switching valve 204 is located on the second passage 202; the power source system is connected to the inlet and the metering tank, and the power source system is used to inject driving fluid into the drug reservoir 100 through the inlet to drive the piston 101 to move, inject the drug in the drug reservoir 100 into the membrane pump 200 and place it in the metering tank; while injecting the drug into the membrane pump 200, the driving fluid in the metering tank is discharged; after the drug injection is completed, driving fluid is injected into the metering tank to discharge the drug in the membrane pump 200 through the second passage 202.

[0075] The drug infusion system of this application allows for multiple infusions after a single drug injection, simplifying the treatment process.

[0076] In one example, please refer to [link / reference]. Figure 5The power source system may include: a power source 205, a third passage 206, a fourth passage 207, a fifth passage 208, a third switching valve 209, a fourth switching valve 210, and a fifth switching valve (not shown); wherein, the power source 205 is used to provide a driving fluid, which may include, but is not limited to, gas; one end of the third passage 206 is connected to the power source 205, and the other end is connected to an inlet; one end of the fourth passage 207 is connected to the power source 205, and the other end is connected to a metering tank; one end of the fifth passage 205 is connected to the metering tank; the third switching valve 209 is located on the fourth passage 207; the fourth switching valve 210 is located on the fifth passage 208; and the fifth switching valve is located on the third passage 206.

[0077] As an example, the first switching valve 203, the second switching valve 204, the third switching valve 209, and the fourth switching valve 210 can all be micro valves and together constitute a micro valve group.

[0078] The working principle of the drug infusion system in this embodiment is as follows: Before operation, the first switch valve 203, the second switch valve 204, the third switch valve 209, and the fourth switch valve are all closed. After operation begins, the driving fluid provided by the power source 205 is input into the drug reservoir 100 through the inlet, pushing the piston 101 to move. At this time, the first switch valve 203 opens, and under the movement of the piston 101, the drug in the drug reservoir 100 enters the membrane pump 200 through the outlet and the first passage 201. The elastic membrane is pressured by the drug and collapses into the metering pool, discharging the driving fluid from the metering pool and discharging it through the fifth passage 208. At this time, the fourth switch valve 210 opens. Figure 5 As shown in Figure (a); after the drug is injected into the membrane pump 200, the first switching valve 203 and the fourth switching valve 210 are closed. When it is necessary to administer the drug to the patient, the third switching valve 209 opens, and the power source 205 provides driving fluid to the metering chamber via the fourth passage 207. Under the pressure of the driving fluid, the drug in the metering chamber is squeezed into the second passage 202 to achieve infusion to the patient. At this time, the second switching valve 204 opens as shown in Figure (a). Figure 5 As shown in Figure (b). After this drug infusion is completed, both the second switch valve 204 and the third switch valve 209 are closed. All the above steps constitute one drug infusion. As needed, the above steps can be repeated several times to achieve multiple drug infusions.

[0079] It should be noted that the first switching valve 203 and the fourth switching valve 210 can be controlled in conjunction or independently, and the second switching valve 204 and the third switching valve 209 can be controlled in conjunction or independently.

[0080] In one embodiment, please refer to Figure 6The power source system may include: a power source 205, a third channel 206, a fourth channel 207, a fifth channel 208, and an air extraction device 211; wherein, the power source 205 is used to provide driving fluid; one end of the third channel 206 is connected to the power source 205, and the other end is connected to the inlet; one end of the fourth channel 207 is connected to the power source 205, and the other end is connected to the metering pool; one end of the fifth channel 208 is connected to the metering pool; and the air extraction device 211 is connected to the end of the fifth channel 208 away from the metering pool.

[0081] The working principle of the drug infusion system in this embodiment is as follows: Before operation, both the first switch valve 203 and the second switch valve 204 are closed; after operation begins, the power source 205 is started, and the driving fluid provided is input into the drug reservoir 100 through the inlet to push the piston 101 to move; at this time, the first switch valve 203 opens, and under the movement of the piston 101, the drug in the drug reservoir 100 enters the membrane pump 200 through the drug outlet and the first passage 201. The elastic membrane is depressed into the metering pool under the pressure of the drug, and the suction device 211 extracts the driving fluid from the metering pool and discharges it through the fifth channel 208. Figure 6 As shown in Figure (a); after the drug is injected into the membrane pump 200, the first switching valve 203 closes. When it is necessary to administer the drug to the patient, the power source 205 is activated, providing driving fluid to the metering chamber via the fourth passage 207. Under the pressure of the driving fluid, the drug in the metering chamber is squeezed into the second passage 202 to achieve drug administration to the patient. At this time, the second switching valve 204 opens, as shown in Figure (a). Figure 6 As shown in Figure (b), after this drug infusion is completed, the second switch valve 204 is closed. All the above steps constitute one drug infusion. As needed, the above steps can be repeated several times to achieve multiple drug infusions.

[0082] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A drug dosage monitoring device, characterized in that, include: A medicine storage device, wherein the medicine storage device has a medicine storage chamber, and the medicine storage device includes a first end and a second end opposite to each other; the first end of the medicine storage device is provided with a medicine outlet. The piston is located inside the drug storage chamber; A fixed electrode is located outside the second end of the drug reservoir and is spaced apart from the drug reservoir. Multiple electrode plates are located between the fixed electrode and the second end of the drug reservoir, and the multiple electrode plates and the fixed electrode are arranged at intervals. A wire-locking device is located on the side of the piston away from the first end of the medicine reservoir; The wire is in contact with both the fixed electrode and the wire clamping device; when the piston moves to different positions within the drug reservoir, the wire is in contact with at least one of the multiple electrode plates.

2. The drug dosage monitoring device according to claim 1, characterized in that, The drug dosage monitoring device further includes: a wire take-up and release device located outside the second end of the drug reservoir and arranged at intervals with the fixed electrode; one end of the wire is connected to the fixed electrode, and the other end is connected to the wire take-up and release device via the wire clamping device.

3. The drug dosage monitoring device according to claim 2, characterized in that, The plurality of electrode sheets include: The first electrode plate is located between the fixed electrode and the take-up and untake-up device; when the piston is in the initial position, the wire is in contact with the first electrode plate; The second electrode plate is located between the fixed electrode and the second end of the drug reservoir; The third electrode is located between the second electrode and the second end of the drug reservoir.

4. The drug dosage monitoring device according to claim 1, characterized in that, The medicine storage device has an inlet at its second end.

5. The drug dosage monitoring device according to claim 4, characterized in that, The dosage monitoring device further includes a pressure release device, which comprises: Release the pipeline and connect it to the inlet; The switching valve structure is located on the release pipeline.

6. The drug dosage monitoring device according to claim 5, characterized in that, The switching valve structure includes: A ball valve is located on the release line; A compression spring is fixed at one end and in contact with the ball valve at the other end.

7. The dosage monitoring device according to any one of claims 1 to 6, characterized in that, The dosage monitoring device also includes: Multiple Hall elements are located on the outer wall of the medicine reservoir and are arranged at intervals along the length of the medicine reservoir; A magnet is located on the piston.

8. A drug delivery system, characterized in that, include: The drug dosage monitoring device as described in any one of claims 1 to 7, wherein the second end of the drug reservoir is provided with an inlet; A membrane pump includes a metering tank and an elastic membrane; the elastic membrane covers the metering tank. The first passage has one end connected to the drug outlet and the other end connected to the membrane pump, and extends above the elastic membrane; The second passage is connected at one end to the membrane pump and extends above the elastic membrane; The first switching valve is located in the first passage. The second switching valve is located in the second passage; A power source system, connected to the inlet and the metering tank, is used to inject driving fluid into the drug reservoir via the inlet to drive the piston to move, inject the drug in the drug reservoir into the membrane pump, and place it in the metering tank; and at the same time as injecting the drug into the membrane pump, discharge the driving fluid in the metering tank. After drug injection is completed, driving fluid is injected into the metering tank to discharge the drug in the membrane pump through the second passage.

9. The drug delivery system according to claim 8, characterized in that: The power source system includes: A power source for providing the driving fluid; The third passage is connected at one end to the power source and at the other end to the inlet; The fourth passage is connected at one end to the power source and at the other end to the metering pool; The fifth pathway has one end connected to the quantitative cell; The third switching valve is located on the fourth passage; The fourth switching valve is located on the fifth passage; The fifth switching valve is located on the third passage.

10. The drug delivery system according to claim 8, characterized in that: The power source system includes: A power source for providing the driving fluid; The third passage is connected at one end to the power source and at the other end to the inlet; The fourth passage is connected at one end to the power source and at the other end to the metering pool; The fifth pathway has one end connected to the quantitative cell; An air extraction device is connected to the end of the fifth passage that is furthest from the metering cell.

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