FR2597630A1 - Method of dispensing a product according to predetermined metered quantities - Google Patents

Abstract

Device for dispensing a product according to predetermined metered quantities, in which the product to be dispensed is enclosed in a reservoir comprising an outlet orifice and with which means are associated which permanently tend to eject the product from the said reservoir. It comprises, on the outlet path for the product out of the said reservoir 10, two adjacent valves or flaps 30, 32, 31, 34 each comprising a calibrated nozzle able to be opened and/or closed, each corresponding to the condition of a deformable piezoelectric crystal 33, 35 and electronic control means 40 for the deformation of the said crystals in order to limit the output of the product out of the said reservoir and thus define a predetermined metered quantity. Application: metering of medication products, for example for injection apparatus.

Description

 The subject of the invention is a device for dispensing a product according to predetermined metered quantities.

 It is, in general, an object of the invention to provide a device for dispensing a product in liquid or gaseous form in predetermined metered quantities, which is very reliable and, therefore, which can be incorporated into precision dosing devices, in particular devices for medical use.

 The invention relates in particular, and without this indication having any limiting nature whatsoever, such a device suitable for being used for delivering, in precise and predetermined quantities, a pharmaceutical product for human or veterinary use, for treatment or for diagnosis.

 A device according to the invention, in which the product to be dispensed is enclosed in a tank comprising an outlet orifice and to which are associated means tending permanently to cause the product to leave the said tank, is characterized in that it comprises , on the product outlet path from said reservoir, two adjacent valves or flaps each comprising a calibrated nozzle capable of being opened and / or closed in correspondence each with the condition of a deformable piezoelectric crystal and electronic control means deformation of said crystals in order to limit the outflow of product from said reservoir and thus define a predetermined metered amount.

 Due to the presence of the two piezoelectrically controlled valves or flaps, a device according to the invention is very reliable in operation, so that it can find application in fields requiring very high reliability such as, for example. example, that of human medicine and, in particular, in a device for injecting liquid, in particular insulin, such as that which is the subject of the French patent application entitled: Device for injecting liquid, in particular at medical use, filed concurrently with this application and in the name of the same applicant.

 In one embodiment, the reservoir of product to be dispensed is a flexible reservoir or a piston system and the means which tend to cause the outlet of the product to be dispensed from said reservoir are means which control the deformation of said reservoir or cause the piston.

 In a particularly advantageous embodiment, said means are constituted by the pressure effect, variable as a function of temperature, of the vapor of a gas, such as a freon chosen so that its vapor pressure characteristics are compatible with the maximum admissible power of the piezoelectric crystals used.

 In this regard, one embodiment provides that said gas is freon 13.

 According to another characteristic of the invention, the device is provided with means suitable for triggering an audible or light alarm signal for pre-established operating conditions, for example when a certain minimum level is reached in the reserve of product to be delivered. , or in the event of a failure of the electronic control circuit, or in the event of a malfunction of the means ensuring the output of the product to be delivered out of the reservoir which contains it.

 In one embodiment, the deformation of one of the piezoelectric crystals is controlled by means of the voltage supplied by a continuous converter whose input is connected to a comparator which receives on the one hand a reference voltage and, on the other hand, a trigger signal.

 In this embodiment, the electronic control means further comprise a first amplifier, an input of which is connected to a terminal of a first piezoelectric crystal having its other terminal to ground, and the output of which is connected to one terminals of a capacitor whose charge current is adjustable by means of a variable resistor for the initial calibration.

 A second amplifier, an input of which is connected to said first piezoelectric crystal and the output of which translates the state of said crystal leads to the DC-DC converter.

 To determine the predetermined metered quantity that the device delivers, the device further comprises time base means for counting the number of trigger pulses applied to the comparator.

Advantageously, the piezoelectric crystals are protected against the action of the product to be distributed by a protective envelope made of a material such as a flexible polymerizable resin, said envelope simultaneously opposing electrical leaks liable to
to deteriorate, by electrolysis or in a similar way, the
product to distribute.

The invention will be better understood from the following description, given by way of example and with reference to the appended drawing in which
- Figure 1 is a schematic view of a device according to the invention;
- Figure 2 is an electronic diagram;
- Figure 3 shows a waveform implemented in a device according to the invention;
- Figure 4 is a partial view, on a larger scale
of scale, of a part of the device shown in Figure 1;
FIG. 5 is a top view corresponding
dante, some parts having been excluded from the others in
a goal of clarity
- Figure 6 is a side view in which
some parts were also discarded from each
others for the sake of clarity.

 A device according to the invention, dispenser of a product in predetermined metered quantities, is shown schematically in FIG. 1. It comprises a reservoir 10 of product to be dispensed, to which are operatively connected, as shown schematically in II, means 12 which permanently tend to control the output from said reservoir of the product it contains.

 In the embodiment described and shown, the reservoir 10 is advantageously a flexible, deformable reservoir, enclosed in an enclosure 13, which also encloses the means 12, preferably constituted by a reserve of gas, - like a freon -, the vapor pressure, at the operating temperature of the device, is chosen to obtain an appropriate pushing force, causing the ejection of the product it contains from the reservoir 10 by deformation of said reservoir. is also organized so that one can easily proceed, at will, to the replacement either of the gas reserve 12 or of the flexible reservoir of product to be dispensed, said reservoir being further provided with means 16, as a valve or the like with watertight closure, intended to allow the initial introduction into the reserve 10 of the product to be dispensed, but which does not prevent it from leaving.

 In a variant, not shown, the product to be dispensed is enclosed in a cylinder and piston system.

 Associated with the reservoir assembly as described above is a metering device 15, interposed between the reservoir 10 of products to be dispensed to which it is connected by a capillary 20 and an outlet nozzle 22 to which it is connected by another capillary 23.

The capillary 20 is interposed on a pipe 21 connecting the metering device proper 15 and the reservoir 10, while the capillary 23 is interposed on a pipe 24 connecting the outlet of the dosing device 15 proper to the nozzle 22.

 The device 15 comprises a first calibrated nozzle or nozzle 30 communicating directly with the capillary 20 and a second calibrated nozzle or nozzle 31 communicating with the capillary 23, said nozzles being advantageously made of a plastic material of the nylon (registered trademark) type injected or stainless steel machined and threaded to a micrometric pitch.

 With the outlet orifice of the nozzle 30 is suitable for cooperating with a member 32 carried by a piezoelectric crystal 33 the prestressing of which brings said member 32 into contact with said orifice to ensure its closure, while the product to be dispensed is escapes through said orifice when the member 32 is moved away by the product under pressure by deforming the piezoelectric crystal, thus causing the appearance of an electric charge at its terminals. Similarly, with the calibrated outlet orifice of the nozzle 31 cooperates a member 34 carried by a piezoelectric crystal 35 whose movement opens or closes the orifice of the nozzle 31, the opening force of the valves formed by said nozzle 31 and the member 34 being limited by the diameter of the capillary 23, which also limits the output flow rate of product to be dispensed.

 According to the invention, the piezoelectric crystals 33 and 35 are controlled by an electronic circuit 40, fifure 2, which comprises an amplifier 41 whose input 42 is connected to a terminal 59 of crystal 33 and whose output 43 is connected to an input 44 of a comparator 45 which receives on a terminal 46 a reference voltage and on another input 47 a trigger signal. The output 48 of the comparator 45 is connected to a DC-DC converter 49 and the output 50 is connected to a terminal of the piezoelectric crystal 35, the other terminal of this being connected to the ground 51.

 As a bypass on the output 43 of the amplifier 41, a capacitor 55 is provided, the charging current of which is adjustable by a variable resistor 56, the voltage across said capacitor 55 being applied to the comparator 45 by an input terminal 57.

 A second amplifier 5E, also connected to terminal 59 of the piezoelectric crystal 33, provides on its output 60, - connected to the converter 49 -, an image of the state of said crystal.

The operation of a device according to the invention is as follows
The reservoir 10 being filled with product and the means 12 being operational, the product to be dispensed tends to come out of said reservoir.

 In an initial condition which is that shown diagrammatically in FIG. 1, the outlet orifice of the nozzle 30 is closed by sealing contact engagement of the member 32 and of said orifice, as is the closed orifice of the nozzle 31 by sealing cooperation with this of the member 34. No voltage exists at the terminals of the piezoelectric crystal 33 or is applied to the terminals of the piezoelectric crystal 35; there is no distribution of product from the reservoir 10.

 If, from this condition, a trigger pulse is applied to the input terminal 47 of the comparator 45, the output 48 of the latter switches and causes the converter 49 to be put into service. The voltage then increases across the terminals of the piezoelectric crystal 35 and, when the voltage across said crystal reaches a value V1 - as shown in the diagram in FIG. 3 in which the time has been plotted on the abscissa and the voltage values at the terminals of the piezo crystal on the ordinate electric 35 -, said crystal effectively and quickly deforms while the voltage across its terminals decreases to be limited to a value V2 for which there is sufficient residual deformation to provide a surface opening equal to the surface of the capillary 23 which limits thus the maximum product flow rate, on the one hand and also limits, on the other hand, the high opening force of the valve constituted by the nozzle 31 and the member 34.

Simultaneously with the deformation of the piezoelectric crystal 35, which controls the opening of the nozzle 31, the piezoelectric crystal 33 is also deformed by the passage of the product, which causes the appearance on its terminal 59 of a voltage which, applied by the input 42 to the amplifier 41 advantageously an amplifier of the type
MOS FET with very high impedance, produces a constant current whose intensity, adjustable via the resistor 56, causes the charging of the capacitor 55, the voltage which appears at the terminals of the latter then being the ir. age of the quantity of product released.

 When this voltage reaches the value of the reference voltage applied to the input 46 of the comparator 45 the output 48 of the latter switches and, la. output of the converter 49 being inverted or brought to zero, as returned on the diagram of FIG. 3, the orifice of the nozzle 31 is closed by return of the crystal 35 to its initial condition and kept closed by the pressure of the gas which s exerts on the piezo crystal which prevents any new release of the product.

The simultaneous return of the crystal 33 to its initial condition, that is to say that in which the member 32 cooperates with the output of the calibrated nozzle 30, reduces the voltage across the terminals of the piezoelectric crystal to zero.

 During this step, the capacitor 55 is also short-circuited so that the appearance of a new trigger pulse on the input 47 controls the progress of a cycle identical to that described above and, consequently, the exit from the reservoir 10 of a new metered, predetermined quantity of product to be dispensed.

 The quantity of product dispensed is then determined, by adjusting and counting, by means not shown, the number of trigger pulses on the input 47 of the comparator 45.

 The output of the amplifier 58, which is the image of the condition of the piezoelectric crystal 33, that is to say of the condition of the valve formed by the member 32 carried by said crystal and the nozzle calibrated 30 -, controls during the cycle defined above the passage from high to medium voltage and it provides, outside the periods corresponding to the opening of the valves of the device 15, an indication of a possible residual flow at the level of the calibrated orifice of the nozzle 30, so that its output can constitute the input signal of an alarm circuit.

 The triggering of the latter can advantageously be dependent on a second time base, the start of which is synchronous with that of the command for applying the trigger pulses to the input 47 of the comparator 45.

 The invention also provides for triggering an alarm in response to factors such as the absence of product in the reserve 10, a failure of the means 12 tending to cause the ejection of the product, a failure of the electronic circuits or of the energy supply of these.

 For the protection of piezoelectric crystals 33 and 35 against the chemical or physicochemical action of the product dispensed, the invention provides for coating said crystals with a polymerizable resin, for example a resin of the flexible epoxy type, a such treatment having the additional advantage of avoiding any electrical leakage liable to deteriorate the product to be dispensed, for example by electrolysis.

 As shown in Figures 4 to 6, the piezoelectric crystals 33 and 35, coated with resin film 70 and 71, respectively, cooperate with the nozzles 30 and 31 formed at the ends of longitudinal holes 72 and 73 drilled in parts 74 and 75 of ogival shape screwed and glued in cylindrical boreholes opposite 76 and 77 of a body 78 of insulating material. There are also mounted pushers 80 and 81 connected electrrluement by means of zones of conductive adhesive 82 and 83, respectively, to the piezoelectric crystals 33 and 35 between which are, moreover, interposed spacers 83 and 84 , also in relation to electrical conduction using a conductive adhesive, for example a silver adhesive, with said crystals.

 With the body 78 cooperate covers 85 and 86 whose attachment to the body is carried out using screws 87 and 88 and sealing by means of seals, not shown.

 A device according to the invention has been produced for the distribution of insulin according to predetermined metered quantities, this indication of course having no limiting character.

 Good results have been obtained using a flexible deformation tank controlled by the action of the vapor pressure of a freon 13, having a value of 28 kg / cm 2 at 300C.

 The diameter chosen for the capillaries was of the order of 72.5 vm, the diameter of the calibrated nozzles of approximately 1000 μm and that of the seats cooperating with said nozzles was approximately 2000 vm.

The piezoelectric crystal # e 33 was of the type
PXE5, bimorph, with a dimension of i2x4x0.6 mm, with a free length of 10 mm and coated, for its insulation, with a flexible polymerized resin, such a crystal being available from the company PHILIPS under the reference 43 22 020 04 610.

 The piezoelectric crystal 35, made of the same material as that of the piezoelectric crystal 33, had dimensions 12 × 6 × 0.6 mm and was available from the company PHILIPS under the reference 43 22 020 04 650.

For such an element, the value of the threshold voltage is around 98 Volts and the value of the opening voltage, for a deflection of 8 vm is around 32
Volts.

Claims (10)

 1. Device for dispensing a product according to predetermined metered quantities, in which the product to be dispensed is enclosed in a reservoir comprising an outlet orifice and to which are associated means tending permanently to cause the product to exit out of said reservoir , characterized in that it comprises on the outlet path of the product out of said reservoir (10) two adjacent valves or flaps (30,32 - 31,34) each comprising a calibrated nozzle suitable for being opened and / or closed in correspondence each of the condition of a deformable piezoelectric crystal (33,35) and electronic control means (40) of the deformation of said crystals to limit the output of product out of said reservoir and thus define a predetermined, dose amount.  2. Device according to claim 1, characterized in that the tank of product to be dispensed is a flexible tank (10) and in that the means causing the output of the product to be dispensed from said tank are means (12) which control the deformation of said reservoir (10).  3. Device according to claim 2, characterized in that said means (12) for deformation of the reservoir (10) are constituted by the effect of pressure, variable as a function of temperature, of the vapor of a gas, such as a freon, contained in an envelope removably mounted in an enclosure (13) which also houses the reservoir (10) of product to be dispensed.  4. Device according to any one of the preceding claims, characterized in that the deformation of one of the piezoelectric crystals (35) is controlled by means of the voltage supplied by a DC-DC converter (49), one of which input is connected to a comparator (45) which receives on the one hand a reference voltage (46) and on the other hand a trigger signal (47).  5. Device according to any one of the preceding claims, characterized in that the electronic control means (40) further comprise a first amplifier (41), one input of which is connected to a terminal (59) of a first piezo crystal. -electric (33) having its other terminal to ground (51) and whose output (43 ', is connected to one of the terminals of a capacitor (55) whose charging current is adjustable via 'a variable resistance (56).  6. Device according to claim 5, characterized in that it comprises a second amplifier (58) whose input is connected to said first piezoelectric crystal (33) and whose output (60), which translates the state of said crystal , leads to the DC-DC converter (49).  7. Device according to any one of claims 4 to 6, characterized in that it further comprises time base means for counting the number of trigger pulses applied to said comparator (45).  8. Device according to any one of the preceding claims, characterized in that it comprises a body (78) of insulating material in which are mounted parts (74,75) providing the calibrated nozzles (30,31), said body also having a space for receiving piezoelectric crystals (33,35) in the form of plates whose positioning is ensured, simultaneously with their electrical connections, by pushers (80,81) housed in the body (78) and spacers (83,84) also housed in said body.  9. Device according to any one of the preceding claims, characterized in that the piezoelectric crystals (33,35) are protected against the action of the product to be dispensed by a protective envelope made of a material such as a flexible polymerizable resin (70,71), said envelope simultaneously opposing electrical leaks liable to deteriorate, by electrolysis or in a similar manner, the product to be dispensed.  10. Device according to any one of the preceding claims, characterized in that it further comprises means suitable for triggering an audible or light alarm signal for pre-established operating conditions.