FREE BEAM DOSING SYSTEM

Abstract

Free jet metering system (100, 300) for metering a fluid free jet to be dispensed (105, 109), comprising: a pump (101) having an inlet (102) and an outlet (103), which is designed to pump fluid (104, 105) to be discharged to the outlet (103), a metering monitoring device (106) arranged on the outlet side of the pump (101), wherein the metering monitoring device (106) has an opening (107) through which at least a part of the fluid (105) to be dispensed can pass, and wherein the metering monitoring device (106) has a flow meter (108) configured to determine the flow rate of the fluid (105) passing through the opening (107) of the metering monitoring device (106), wherein the opening (107) of the metering monitoring device (106) is designed as an outlet nozzle (107) for ejecting the fluid free jet (109), and wherein the outlet nozzle (107) has a laterally circumferential collar (501).

Description

[0001] The invention relates to a free-jet dosing system with the features of claim 1.

[0002] Free jet dosing systems are used in numerous fields of technology, such as medical technology, laboratory technology, diagnostics or production technology.

[0003] The physical mechanisms for free-jet dispensers are divided into two main types: the pressure pulse principle and the jet principle. In the pressure pulse principle, a very short pressure pulse is generated in a liquid chamber, for example, by a bubble created by heating, a so-called "bubble jet," or by a piezoelectric element. With the pressure pulse principle, no volume is displaced. The pressure pulse propagates to the nozzle, where a droplet of a typical size of 0.05 nanoliters is released.

[0004] In the jet principle, a volume typically in the range of about 50 nanoliters is displaced, for example by a piezoelectric membrane actuator. This volume is then expelled through a nozzle as a long jet, also known as a free jet.

[0005] Both systems frequently experience disturbances in the form of gas bubbles. The pressure pulse principle is very sensitive to gas bubbles in the liquid chamber, as these significantly dampen the pressure pulse, preventing any further droplets from being released.

[0006] In jet dispensers, a gas bubble also reduces the pressure amplitude, depending on the compression ratio between the stroke volume and the chamber volume, thus disrupting the free jet. Furthermore, many jet dispensers rely on the capillary action of a meniscus formed at the nozzle to prevent backflow of liquid during refilling. If a gas bubble is present at the nozzle, the meniscus is absent, and refilling is disrupted. This leads to the failure of the jet dispenser.

[0007] An improvement on the jet dispenser is the free-jet dispenser known from WO 03 / 095837 A1, which combines a self-priming micropump with a nozzle chip. Here, too, the dosing accuracy of the jet depends on the presence of gas bubbles. Furthermore, this free-jet dispenser is not suitable for dosing a liquid if a gas bubble is being pushed out of the nozzle.

[0008] Therefore, for many applications, monitoring of the free jet or the amount of liquid delivered in the form of the free jet is necessary.

[0009] Several methods are currently known for monitoring the successful delivery of a free jet. One method involves optical monitoring of the amount of liquid delivered in a free jet. Another is capacitive monitoring of the amount of liquid delivered in a free jet. However, these monitoring methods are sometimes very complex to implement and require additional components, such as optical or capacitive sensor elements. This generally results in such monitoring devices being expensive and complex to manufacture.

[0010] For metering a fluid flow, a metering device element is known, for example, from WO 98 / 48 330 A1. The metering device element has a membrane with an opening that presents a flow resistance to the medium to be metered as it flows through this opening. The membrane for metering a fluid flow is a thin semiconductor membrane. Therefore, the membrane is unsuitable for metering a high-pressure jet instead of a fluid flow.

[0011] DE 44 33 894 A1 describes a metering system for a micro-diaphragm pump whose delivery direction is defined by its valve structure. The delivery direction is selectively reversed when a drive signal with a given excitation frequency is applied to the pump. The excitation frequency lies in a frequency range above the resonance frequency of the resonance system generated by the moving parts of the pump and the pumped fluid. There is a phase difference of between 90 and 180 degrees between the drive signal and the deflection of the valve structure.

[0012] In WO 2003 / 095 837 A1, a method and a device for controlling a micropump by means of a driver signal are described, in such a way that a delivery direction defined by a valve structure is reversed, whereby the driver signal is applied to the micro-diaphragm pump with an excitation frequency, wherein the excitation frequency lies in the range of a resonance of a system formed from the moving parts of the micropump and the fluid to be pumped.

[0013] US Patent 2011 / 0142688A1 describes a pumping device comprising a pump with a variable-volume pumping chamber, an inlet communicating with the pumping chamber and containing a valve, an outlet communicating with the pumping chamber and containing a valve, an actuator capable of changing the volume of the pumping chamber, and a fluidic path comprising the inlet, the pumping chamber, the outlet, and a downstream line located below the outlet valve. The pumping device also includes a pressure sensor for measuring the pressure between the valves of the path and processing means for processing the pressure data received from the pressure sensor. The patent also describes a method for detecting a malfunction in a pumping device.

[0014] It is an object of the present invention to improve free jet dosing systems in such a way that the amount of fluid dispensed can be precisely monitored and the free jet dosing system is simultaneously insensitive to disturbances, and yet can be manufactured simply and cost-effectively.

[0015] This problem is solved according to the invention by a free jet metering system for metering a fluid free jet to be dispensed, having the features of claim 1.

[0016] The free-jet metering system according to the invention for metering a fluid free jet to be dispensed comprises, among other things, a pump having an inlet and an outlet, which is configured to convey the fluid to be dispensed to the outlet. The free-jet metering system further comprises a metering monitoring device arranged on the outlet side of the pump, wherein the metering monitoring device has an opening through which at least a portion of the fluid to be dispensed passes, and wherein the metering monitoring device has a flow meter configured to determine the flow rate of the fluid passing through the opening of the metering monitoring device. According to the invention, the opening of the metering monitoring device is configured as an outlet nozzle for ejecting and shaping the fluid free jet.The metering monitoring device can determine the dispensed fluid quantity by measuring the amount of fluid passing through the opening formed in the device. Because the metering monitoring device is mounted on the outlet side of the pump, the dispensed fluid can be expelled through this opening. The opening is designed to shape the jet, expelling the dispensed fluid as a free jet. The pump generates high pressures of up to 40 bar. The opening in the metering monitoring device thus acts as a high-pressure resistant nozzle, expelling a precisely shaped free jet and simultaneously serving as a flow resistance for measuring the dispensed fluid quantity.The underlying principle is that at the nozzle, the potential energy of the pressure is converted into the kinetic energy of the free jet, and the entire pressure drops at the nozzle. Therefore, the metered quantity can be determined by measuring the pressure. Because the opening of the metering monitoring device is designed as a nozzle, a separate nozzle chip is unnecessary. Furthermore, on the side of the metering monitoring device facing the pump outlet, the fluid flows through it at a constant pressure. This means that the metering monitoring device is not directly exposed to a free jet; rather, the free jet is generated at the nozzle outlet.

[0017] According to one embodiment, the metering monitoring device is arranged in contact with the pump outlet, at least in certain sections. This creates a direct connection, at least in certain sections, between the pump outlet and the metering monitoring device. The distance the fluid has to travel between the pump outlet and the metering monitoring device can therefore be advantageously kept short. The pump pressure can thus be transmitted to the metering monitoring device with virtually no loss.

[0018] It is conceivable that the pump is a micropump. This would allow the entire free-jet dosing system to have small and compact dimensions.

[0019] The micropump can comprise a pump chamber arranged between the inlet and the outlet, a diaphragm located at least partially within the pump chamber, and a diaphragm deflection device. The diaphragm deflection device is designed to deflect the diaphragm such that the volume of the pump chamber is increased to draw in the fluid to be discharged, and the volume of the pump chamber is decreased to discharge the fluid. Such diaphragm-controlled micropumps are well suited for generating, particularly intermittently, pressure pulses. The pump does not generate continuous pressure but rather a pressure pulse or a sequence of pressure pulses. Thus, a transient, time-varying pressure signal is present at the dosing monitoring device. Detection of an orifice blockage can be achieved by analyzing this transient signal.With a static flow, the dosing monitoring device cannot distinguish whether the opening is blocked. However, the transient, time-dependent signal at the dosing monitoring device differs depending on whether the opening is blocked or not. If the opening is not blocked, the pressure pulse generated by the pump will dissipate within a few milliseconds. If the opening is blocked, overpressure builds up, but cannot escape. This can be detected, for example, by signal analysis of the dosing monitoring device.

[0020] It is conceivable that the membrane deflection mechanism is a piezoelectric element designed to deflect the membrane depending on the voltage applied to the piezoelectric element. This would allow low voltages to be sufficient to operate the pump. Furthermore, high pump operating rates, such as 500 Hz, could be achieved with the piezoelectric element.

[0021] It is conceivable that the pump has a check valve on the outlet side that closes the outlet when the pump draws in the fluid to be discharged and opens the outlet when the pump discharges the fluid. These valves prevent unwanted backflow of the discharged fluid. Thus, during the pump's discharge stroke, these valves allow the discharged fluid to exit through the outlet valve. However, during the pump's suction stroke, closing the outlet is desired to allow fresh discharged fluid to be pumped through the inlet into the pump chamber. Therefore, these valves close the outlet during the pump's suction stroke, thus preventing unwanted backflow of the discharged fluid through the outlet.

[0022] It is also conceivable that the free-jet metering system has a nozzle chamber located between the pump outlet and the outlet nozzle, and that the check valve is located between the pump outlet and the nozzle chamber. In this way, the pressure required to eject the free jet can be built up before the nozzle chamber, i.e., in the pump chamber located upstream of the nozzle chamber, since the check valve separates the nozzle chamber from the pump chamber.

[0023] It is conceivable that the free-jet dosing system includes a control device designed to actuate the flow meter and the pump in such a way that the flow meter detects fluid flow from the nozzle chamber to the pump chamber when the pump draws in the fluid to be dispensed. During the pump's suction stroke, the check valve on the outlet side is fluid-tight. Should the outlet valve leak, the fluid in the nozzle chamber flows past the defective check valve and back into the pump chamber. Since the flow meter can detect fluid flow from the nozzle chamber to the pump chamber during the suction stroke, leakage currents or defects in the check valve on the outlet side can thus be detected.

[0024] According to one embodiment, the control device can be configured to compare the quantity of a delivered fluid free jet, determined by the flow meter, with a reference value and generate a signal if the delivered quantity is less than the reference value. The control device thus monitors the actual quantity of fluid delivered during a pump stroke. The reference value can, for example, correspond to a desired delivery quantity, e.g., 10 nl. If the flow meter measures less than 10 nl during a pump stroke, the control device can output a signal indicating the insufficient delivery quantity. This signal can then be evaluated by the control device, which, if necessary, triggers another pump stroke to reach or, if required, exceed the metering volume reference value.A delivery volume that is too low can also indicate that, for example, the inlet valve is leaking. In the case of a defective inlet valve, part of the stroke volume is returned to the inlet line during the pressure stroke and not pumped into the nozzle chamber.

[0025] The reduced delivery quantity is measured by the dosing monitoring device using the flow meter. It is also conceivable that a measured flow rate below the reference value could indicate that the pump diaphragm is losing stroke volume.

[0026] The control device can be configured to determine a time-varying instantaneous value of the fluid pressure applied to the opening of the metering monitoring device located on the outlet side. When the pump's stroke volume is discharged through the outlet valve, a defined, time-dependent overpressure is generated. This overpressure opens the outlet valve. The flow meter measures a rapidly rising pressure signal at the nozzle. As the free jet of fluid, typically incompressible, is ejected, the pressure in the pump chamber and at the nozzle decreases over time. More precisely, the control device measures the pressure difference between the side of the nozzle facing the pump outlet and the outlet side facing away from the pump outlet. This pressure difference changes over time.For example, at the beginning of a pump stroke, a high initial pressure is present on the side of the nozzle facing the pump outlet, which is higher than the pressure on the side of the nozzle facing away from the pump outlet (e.g., ambient pressure). The rising edge of the pressure profile on the side of the nozzle facing the pump outlet thus rises steeply at the beginning of the pump stroke. The closer the pump stroke approaches its end, the more fluid has already flowed through the nozzle. Accordingly, the overpressure on the side of the nozzle facing the pump outlet decreases continuously compared to the overpressure on the side facing away from the pump outlet. The pressure profile or pressure signal therefore exhibits a falling edge over time. The flow meter can determine instantaneous values ​​of this transient, continuously changing pressure and, if necessary, integrate them over time.

[0027] The control device can be configured to determine the time-dependent fluid flow through the opening using the measured, time-varying fluid pressure at the opening and the static characteristic curve of the opening. This determined fluid flow can then be integrated over time to calculate the volume of the metered free jet of fluid. The metering monitoring device is designed to determine the amount of fluid flowing through the outlet nozzle using the flow meter based on the transient, i.e., time-dependent, pressure signal. The metering monitoring device is configured such that the time-dependent fluid flow through the opening or nozzle can be determined from the measured, time-dependent pressure signal and the static characteristic curve of the opening used as a nozzle. This fluid flow can then be integrated over time to determine the metered volume or flow rate.Based on the pressure, the dosing monitoring device can therefore measure or determine the flow rate of the fluid to be dispensed flowing through the opening or nozzle using the flow meter.

[0028] According to a further embodiment, the control device can be configured to determine the amplitude of the fluid pressure at the opening of the metering monitoring device when a free jet of fluid is discharged and to compare it with an amplitude reference value, and / or to measure the time required for pressure equalization at the opening and to compare it with a time reference value. This allows the device to detect a gas bubble in the pump chamber if the determined amplitude value is smaller than the amplitude reference value and / or the measured time for pressure equalization is greater than the time reference value. A gas bubble in the pump chamber causes the pressure amplitude to decrease and the pressure equalization to take longer. Both of these effects can be measured by the metering monitoring device.

[0029] According to a further embodiment, the free-jet metering system can have a nozzle chamber arranged between the pump outlet and the outlet nozzle, and the control device can be configured to determine a value of the amplitude of the fluid pressure applied to the opening of the metering monitoring device when a free jet of fluid is discharged and to compare it with an amplitude reference value, and / or to measure the time required for a pressure rise at the opening and to compare it with a time reference value in order to detect a gas bubble in the nozzle chamber if the determined amplitude value is smaller than the amplitude reference value and / or the measured time for the pressure rise is greater than the time reference value. Depending on the size of the gas bubble, a gas bubble in the nozzle chamber causes it to be compressed by the pressure pulse, thereby reducing the pressure amplitude and delaying the pressure rise edges.

[0030] According to one embodiment, the pump can be designed as an intermittently operating pump. In this configuration, the pump generates a pressure pulse or a sequence of pressure pulses. This results in a transient, time-varying pressure signal at the metering monitoring device or at the nozzle. A blockage of the opening or nozzle can be detected by analyzing this transient signal. With a static flow, the flow meter cannot distinguish whether the nozzle is blocked. However, the transient, time-dependent signal at the nozzle differs depending on whether the nozzle is blocked or not. If the nozzle is not blocked, the pressure pulse generated by the pump will dissipate within a few milliseconds. If the nozzle is blocked, overpressure builds up, but cannot dissipate. This can be detected by signal analysis.

[0031] Further embodiments of the invention are described below, wherein the further embodiments can be combined with all embodiments claimed in the patent claims.

[0032] According to a first conceivable embodiment, a free-jet metering system for metering a free jet of fluid is described, wherein the free-jet metering system comprises a pump having an inlet and an outlet, configured to convey the fluid to be dispensed to the outlet, and a metering monitoring device arranged on the outlet side of the pump, wherein the metering monitoring device has an opening through which at least a portion of the fluid to be dispensed can pass, and wherein the metering monitoring device comprises a flow meter configured to determine the flow rate of the fluid passing through the opening of the metering monitoring device. The opening of the metering monitoring device is configured as an outlet nozzle for ejecting the free jet of fluid, and wherein the free-jet metering system further comprises means for calibrating and / or detecting disturbances of the free-jet metering system.

[0033] According to a second conceivable embodiment, which can be combined with the first embodiment, the free jet metering system can further have an inlet-side flow sensor which has an opening and a flow meter, wherein the flow meter is designed to determine the flow rate of a fluid passing through this opening.

[0034] According to a third conceivable embodiment, which can be combined with the first or second embodiment, the means for calibrating and / or detecting disturbances of the free-jet dosing system can include a control device configured to detect an actual sensor signal from the flow sensor and / or the dosing monitoring device when the pump is inactive, and to correct subsequent sensor signals from the flow sensor and / or the dosing monitoring device based on this.

[0035] According to a fourth conceivable embodiment, which can be combined with the previous embodiments, the control device can be configured to determine a correction value and subtract this from the amount of the detected actual sensor signal of the flow sensor and / or the metering monitoring device, wherein the obtained difference value forms a corrected starting point for the subsequent sensor signals of the flow sensor and / or the metering monitoring device.

[0036] According to a fifth conceivable embodiment, which can be combined with the third or fourth embodiment, the control device can be configured to determine a correction value whose amount corresponds to the amount of the detected actual sensor signal of the flow sensor and / or the dosing monitoring device.

[0037] According to a sixth conceivable embodiment, which can be combined with the third or fourth embodiment, the control device can be configured to determine a correction value, the amount of which is within a range of the amount of the detected actual sensor signal plus a tolerance value of ±10% of the measured sensor signal or plus a tolerance value of ±20% of the measured sensor signal.

[0038] According to a seventh conceivable embodiment, which can be combined with the previous embodiments, the control device can be configured to detect the actual sensor signal of the flow sensor and / or the metering monitoring device and to correct subsequent sensor signals of the flow sensor and / or the metering monitoring device before any pump stroke or before each pump stroke.

[0039] According to a fourth conceivable embodiment, which can be combined with the previous embodiments, the free jet metering system can have the same pressure on the inlet side as on the outlet side or a lower pressure than on the outlet side.

[0040] According to a ninth conceivable embodiment, which can be combined with the previous embodiments, the free jet metering system can have an inlet-side and / or outlet-side valve, wherein the valve is an active normally closed valve and / or an active normally open valve and / or a valve with a threshold pressure that is closed below a threshold pressure and / or a double normally closed microvalve and / or a safety valve.

[0041] According to a tenth conceivable embodiment, which can be combined with the previous embodiments, the means for calibrating and / or detecting disturbances in the free-jet metering system may include a control device configured to control the pump, the metering monitoring device, and the inlet-side flow sensor in such a way that both the metering monitoring device and the flow sensor determine the flow rate of the fluid flowing through the respective opening of the metering monitoring device and the flow sensor when the pump draws in the fluid to be dispensed, and wherein the control device is further configured to compare the flow rate determined by the metering monitoring device and the flow rate determined by the flow sensor.

[0042] According to an eleventh conceivable embodiment, which can be combined with the ninth or tenth embodiment, the means for calibrating and / or detecting disturbances of the free-jet metering system can include a control device configured to control the pump, the metering monitoring device, and the inlet-side flow sensor in such a way that the metering monitoring device and the flow sensor determine the flow rate of the fluid flowing through the respective opening of the metering monitoring device and the flow sensor when the pump discharges the fluid to be dispensed from the outlet, and wherein the control device is further configured to compare the flow rate determined by the metering monitoring device and the flow rate determined by the flow sensor.

[0043] According to a twelfth conceivable embodiment, which can be combined with the previous embodiments, the pump can have a pump chamber arranged between the inlet and the outlet, a diaphragm arranged at least partially in the area of ​​the pump chamber, and a diaphragm deflection means, wherein the diaphragm deflection means is designed to deflect the diaphragm in such a way that the volume of the pump chamber is increased to draw in the fluid to be discharged, and the volume of the pump chamber is decreased to discharge the fluid to be discharged.

[0044] According to a thirteenth conceivable embodiment, which can be combined with the twelfth embodiment, the membrane deflection means can be a piezoelectric element designed to deflect the membrane depending on the voltage applied to the piezoelectric element.

[0045] According to a fourteenth conceivable embodiment, which can be combined with the previous embodiments, the free-jet metering system can have a control device configured to compare the flow rate determined by means of the metering monitoring device with a predetermined flow rate comparison value and to control the pump until the flow rate determined by means of the metering monitoring device is equal to or greater than the predetermined flow rate comparison value.

[0046] According to a fifteenth conceivable embodiment, which can be combined with the previous embodiments, fluid connecting means can be arranged between the pump and the metering monitoring device and / or between the pump and the flow sensor, which have a low fluidic capacity, in particular fluid connecting means whose volume remains constant when the operating pressure of the pump changes and / or fluid connecting means which have a low fluidic inductance.

[0047] Exemplary embodiments of the invention are shown in the drawing and are explained below. They show: Fig. 1A a free jet dosing system according to the invention, Fig. 1B a further embodiment of a free jet metering system according to the invention, Fig. 2A a side sectional view of a free jet metering system according to the invention in a first embodiment, Fig. 2B another lateral sectional view of the free jet dosing system according to the invention Fig. 2A, Fig. 3 a lateral sectional view of a free jet metering system according to the invention in a second embodiment, Fig. 4 diagrams showing different pressure profiles, and Fig. 5A to 5E different nozzle shapes, with the ones in the Fig. 5A, Fig. 5B, Fig. 5D and Fig. The nozzle shapes shown in section 5E represent exemplary embodiments of the invention.

[0048] Fig. Figure 1A shows a free-jet metering system 100 according to the invention for metering a free jet of fluid to be dispensed. The fluid to be dispensed can be, for example, a gas or a liquid. The fluid can have different rheological properties. For example, the fluid can have a low viscosity. The fluid can contain pharmaceutically active components. The free jet of fluid can be shaped by the outlet nozzle in such a way that it is suitable for subcutaneous injection.

[0049] The in Fig. The free-jet dosing system 100 shown in Figure 1A includes, among other things, a pump 101. The pump 101 has an inlet 102 and an outlet 103. The pump 101 is designed to draw in the fluid 104, 105 to be dispensed through the inlet 102 and pump it to the outlet 103.

[0050] The free-jet metering system 100 further comprises a metering monitoring device 106. The metering monitoring device 106 is arranged on the outlet side of the pump 101, i.e., it is located on the side of the outlet 103 of the pump 101. The metering monitoring device 106 has an opening 107 through which at least a portion of the fluid 105 to be dispensed can pass.

[0051] The metering monitoring device 106 also includes a flow meter 108. The flow meter 108 is designed to determine the flow rate of the fluid 105 passing through the opening 107 of the metering monitoring device 106.

[0052] The opening 107 of the metering monitoring device 106 is designed as an outlet nozzle 107 for ejecting a free jet of fluid 109. As can be seen, the free jet of fluid 109 emerges from the side of the nozzle 107 facing away from the pump 101 and continues to move in a direction away from the pump 101, as indicated by arrow 110.

[0053] Fig. Figure 2A shows an embodiment of the free-jet metering system 100 according to the invention. The free-jet metering system 100 has a pump 101. The pump 101 has an inlet 102 and an outlet 103.

[0054] More precisely, the inlet 102 has an inlet opening 102a and a rim section 102b surrounding the inlet opening 102a. The outlet 103 has an outlet opening 103a and a rim section 103b surrounding the outlet opening 103a. In the Fig. In the embodiment shown in 2A, the edge section 102b surrounding the inlet opening 102a and the edge section 103b surrounding the outlet opening 103a are formed in one piece.

[0055] According to this embodiment, the metering monitoring device 106 is arranged on the outlet side and is in contact with the outlet 103 of the pump 101, at least partially. More precisely, the sections 203a, 203b of the metering monitoring device 106 adjacent to the pump 101 are in contact with the edge section 103b of the outlet 103 surrounding the outlet opening 103a.

[0056] Pump 101 is designed to draw in the fluid 104 to be dispensed through inlet 102. A reservoir 201, which stores the fluid 104 to be dispensed, can be arranged on the inlet side of pump 101. Pump 101 draws the fluid 104 to be dispensed from reservoir 201.

[0057] However, both an inlet-side reservoir 201 and an outlet-side reservoir (not shown here) can be provided. The fluid pressures of the two reservoirs can be designed to be equal. In this case, the microdosing system 100 would therefore have approximately the same pressure on the inlet side as on the outlet side. This prevents free fluid flow between inlet 102 and outlet 103.

[0058] However, the pressure of the outlet-side reservoir can also be greater than the pressure of the inlet-side reservoir 210. In this case, the check valve 210, described below, ensures that no unwanted backflow from the outlet-side reservoir to the pump 101 can occur.

[0059] The pump 101 is further designed to discharge at least a portion of the fluid, indicated by the arrow 105, from the outlet 103.

[0060] The outlet-side metering monitoring device 106 has an opening 107 through which the fluid 105 to be dispensed can pass. The opening 107 acts as a nozzle through which a free jet 109 can be ejected.

[0061] The metering monitoring device 106 further comprises a flow meter 108. The flow meter 108 is designed to determine the flow rate of the fluid 105 passing through the opening 107 formed in the metering monitoring device 106. In other words, the metering monitoring device 106 monitors the dispensed fluid quantity.

[0062] The monitoring of the flow rate using the dosing monitoring device 106 is carried out as follows: The opening 107 formed in the dosing monitoring device 106 can also be referred to as an orifice. The flow meter 108 can, for example, be a pressure sensor that measures the pressure upstream and downstream of the orifice 107 and can determine the differential pressure. As described below, the flow rate passing through the orifice 107 can be determined using the differential pressure. By integrating the flow rate over time, the flow rate or volume of the fluid 105 passing through can be determined. Thus, the free-jet dosing system 100 can monitor and precisely meter the quantity of fluid 105 to be dispensed in the form of a free jet 109.

[0063] The opening or aperture 107 forms a defined flow resistance for the fluid 105 flowing through it. The volumetric flow rate or mass flow rate flowing through this flow resistance 107 is a function of the pressure applied to it. The volumetric flow rate Q is (for incompressible fluids with not too high viscosity, according to Torricelli's law) proportional to the square root of the pressure difference Δp between the pressure p1 measured before the aperture 107 and the pressure p2 measured after the aperture 107, with a proportionality constant c. Q=c⋅p2−p1=c⋅Δp Or more generally: Q=μA2Δpρ with the aperture area A and the density ρ of the liquid. The outflow coefficient µ is composed of the contraction coefficient λ (which describes the narrowing of the flow path at sharp aperture edges) and the velocity coefficient ζ (which describes the influence of the (small) friction losses at the aperture). μ=λζ

[0064] The above root-shaped Toricelli relationship further requires that the aperture 107 be an "orifice," meaning that the diameter (or typical dimension in the case of a non-circular, e.g., square, aperture) of the aperture 107 is significantly larger than the thickness of the aperture 107. This is the case, for example, when the aperture 107 of the dosing monitoring device 106 is realized, for instance, by a dry etching step on a silicon pressure sensor membrane, which typically has a membrane thickness of 10 to 50 µm and a typical membrane side length of 1 to 3 mm, and the diameter of the aperture 107 has a value of 50 to 1500 µm. If the diameter of the aperture 107 is significantly larger than the thickness of the aperture 107, the potential energy of the fluid 105 is mainly converted into kinetic energy, thus giving rise to the above Toricelli law.In this case, the influence of friction on the orifice flow is small, which has the advantage that the liquid flow through the orifice 107 is essentially independent of temperature, since density is essentially temperature-independent, whereas viscosity in liquids is highly temperature-dependent. The disadvantage here is that (due to the steep root characteristic curve at small sensor signals) the dosing monitoring device 106 is less sensitive at low flow rates.

[0065] If the diameter of orifice 107 is not significantly larger than its thickness, the influence of friction increases. The root characteristic then acquires a linear component. However, this is irrelevant for the function of the free-jet dosing system 100, as the relationship between the pressure sensor signal and the flow rate can still be determined. Since the influence of viscosity on temperature is also known, this temperature influence can be measured and compensated for by measuring the temperature (as previously described for gas flow). Furthermore, channel flow has the advantage that an approximately linear relationship results between flow rate and pressure drop, which is generally known for a round channel geometry due to Hagen-Poiseuill's law.

[0066] This makes it possible, for example, to realize aperture diameters that are equal to or smaller than the aperture thickness (making the aperture 107 a channel), and thus free jet dosing systems 100 can also be realized that can monitor and dose very small quantities.

[0067] The volume flow rate or flow rate Q is also the time derivative of the volume of fluid to be discharged flowing through the defined flow resistance (corresponding to the cross-section of the aperture 107) during a unit of time. Q=V˙=dVdt

[0068] Integrating the volume flow rate Q yields the volume of the medium that flowed through during this period. V=∫t1t2Qdt

[0069] As mentioned previously, the fluid 105 to be dispensed can also be a gas. In this case, the volume of the gas changes with temperature. Therefore, it can be advantageous if the free-jet metering system 100 has a temperature sensor (not shown here) designed to determine the temperature of the gas passing through the aperture 107 in order to determine the corresponding volume of the gas. Advantageously, the temperature sensor is integrated into the metering monitoring device 106. If the metering monitoring device 106 is designed, for example, as a microflow sensor in the form of a semiconductor chip, the temperature sensor can also be integrated into this semiconductor chip.

[0070] According to the invention, the opening 107 formed in the metering monitoring device 106 is designed such that it serves as an outlet nozzle for ejecting the fluid 105 in the form of a free jet 109. The outlet nozzle 107 is further designed to shape the jet, i.e., the outlet nozzle 107 is such that the fluid 105 to be dispensed is ejected as a continuous free jet 109. The pump 101 can generate pressures of up to 40 bar.

[0071] Pump 101 has a check valve 210 on its outlet side, which closes the outlet 103 when pump 101 draws in the fluid 104 to be discharged, i.e., when pump 101 performs a suction stroke. The outlet-side check valve 210 opens the outlet 103 when pump 101 discharges the fluid 105 from the outlet 103, i.e., when pump 101 performs a pressure stroke. Thus, the outlet-side check valve 210 closes the outlet 103 during a suction stroke of pump 101 and opens the outlet 103 during a pressure stroke of pump 101.

[0072] Fig. 2B shows the free jet dosing system made of Fig. 2A again, but for the sake of clarity, omitting some of the previously described features, such as the inlet-side reservoir 201.

[0073] In Fig. Figure 2B shows that pump 101 also has a check valve 211 on its inlet side. The inlet-side check valve 211 opens the inlet 102 when pump 101 draws in the fluid 104 to be discharged. Conversely, the inlet-side check valve 211 closes the inlet 102 when pump 101 discharges the fluid 105 from the outlet 103. Thus, the inlet-side check valve 211 opens the inlet 102 during a suction stroke of pump 101 and closes the inlet 102 during a pressure stroke of pump 101.

[0074] The pump 101 used in the free-jet metering system 100 according to the invention can preferably be designed as a micropump with small dimensions. The micropump 101 has a pump chamber 202 arranged between the inlet 102 and the outlet 103, through which the fluid to be dispensed is conveyed from the inlet 102 to the outlet 103.

[0075] The micropump 101 also has a diaphragm 220 and a diaphragm deflection means 221, which are arranged at least partially in the area of ​​the pump chamber 202. The diaphragm deflection means 221 is designed to deflect the diaphragm 220 such that the volume of the pump chamber 202 is increased to draw in the fluid 104 to be discharged, and the volume of the pump chamber 202 is decreased to discharge the fluid 105 to be discharged.

[0076] In this micropump, for example, the lateral dimension of the pressure sensor diaphragm 220 is preferably in a range of 2x2 mm. 2 up to 5x5 mm 2 The membrane thickness is preferably in a range between 20 µm and 60 µm. The diameter of the opening or nozzle 107 can, for example, be in a range between 10 µm and 100 µm. The membrane 220 can also have a plurality of openings or nozzles 107.

[0077] The membrane deflection means 221 is preferably a piezoelectric element designed to deflect the membrane 220 depending on the voltage applied to the piezoelectric element 221.

[0078] As further explained in Fig. As can be seen in Figure 2B, the outlet-side metering monitoring device 106 has a cavity 205 facing the outlet 103 of the pump 101. The cavity 205 is thus located between the outlet nozzle 107 and the pump outlet 103. This cavity 205 contains the fluid 105 to be dispensed. Normally, the cavity 205 is completely filled with the fluid 105, provided no gas bubbles are present in the cavity 205.

[0079] Since the opening 107 of the metering monitoring device 106 is designed as an outlet nozzle, the cavity 205 is also referred to as a nozzle chamber. As shown in the Fig. 2A and Fig. As can be seen in Figure 2B, the outlet-side check valve 210 is arranged between the pump chamber 202 and the nozzle chamber 205. The outlet-side check valve 210 thus provides a spatial and fluid-tight separation between the nozzle chamber 205 and the pump chamber 202.

[0080] If the outlet-side check valve 210 should leak, fluid 105 to be dispensed, for example when the pump 101 is inactive, flows from the pump chamber 202 past the leaking check valve 210 into the nozzle chamber 205. The amount of fluid 105 to be dispensed in the nozzle chamber 205 then increases and can escape through the opening 107 from the metering monitoring device 106.

[0081] The free jet metering system 100 according to the invention can detect such a leaking check valve 210 by measuring the excess fluid volume escaping through the opening 107 by the metering monitoring device 106 using the flow meter 108.

[0082] If the outlet-side check valve 210 is leaking, it can also happen that the fluid 105 located in the nozzle chamber 205 is drawn from the nozzle chamber 205 into the pump chamber 202 during a suction stroke of the pump 101. Furthermore, a leaking outlet-side check valve 205 is disadvantageous because air could be drawn in through the nozzle 107 during a suction stroke, and this air could settle as a gas bubble in the nozzle chamber 105 and / or in the pump chamber 202.

[0083] To detect a leaking outlet-side check valve 210, it is advantageous for the free-jet metering system 100 to know the state of the pump 101. The presence of a leaking outlet-side check valve 210 is generally only plausible if, as described above, the pump 101 is either inactive or performing a suction stroke when measuring fluid flow through the nozzle 107. This is because, in these pump states, a properly functioning outlet-side check valve 210 is fluid-tight.

[0084] In order to enable the free jet metering system 100 according to the invention to establish a synchronization between pump state and flow rate measurement, the free jet metering system 100 has a control device 302 which detects the operating state of the pump 101.

[0085] The control unit 302 can, for example, be a suitable microcontroller. The control unit 302 is connected to the free-jet dosing system 100 via a wired or wireless connection 303. The control unit 302 is preferably connected to the pump 101 and to the dosing monitoring device 106.

[0086] The control device 302 is designed to control the flow meter 108 and the pump 101 in such a way that the metering monitoring device 106 can detect a fluid flow exiting from the nozzle 107 to the outside by means of the flow meter 108 even when the pump 101 is in an inactive state.

[0087] The control unit 302 also detects when fluid unintentionally flows from the nozzle chamber 205 to the pump chamber 202 when the pump 101 draws in the fluid 104 to be dispensed, i.e. when the pump 101 performs a suction stroke.

[0088] This suggests that the outlet-side check valve 210 is leaking, since an intact check valve 210 is fluid-tight when inactive or during the suction stroke of the pump 101, and the leakage currents described above should therefore not occur with an intact valve 210.

[0089] Fig. Figure 3 shows a further embodiment of a free-jet metering system 300 according to the invention. This embodiment differs from the embodiments discussed so far in that a flow sensor 110 is provided on the inlet side. The other features of the free-jet metering system correspond to those previously described with reference to the Fig. 1, Fig. 2A and Fig. 2B described characteristics, which is why the same reference symbols are used for the same characteristics.

[0090] The flow sensor 110 has an opening 111 and a flow meter 112. The flow meter 112 is designed to determine the flow rate of the fluid 104 passing through this opening 111. The flow meter 112 of the flow sensor 110 functions analogously to the flow meter 108 of the dosing monitoring device 106 described above.

[0091] According to this embodiment, the flow sensor 110 is arranged on the inlet side and is in contact with the inlet 102 of the pump 101, at least partially. More precisely, the sections 304a, 304b of the flow sensor 110 adjacent to the pump 101 are in contact with the edge section 102b of the inlet 102 surrounding the inlet opening 102.

[0092] The free jet metering system 300 has a valve 310 on the outlet side, which is designed to close the outlet 103 when the pump 101 draws in the fluid 104 to be dispensed.

[0093] The valve 310 is further designed to open the outlet 103 when the pump 101 discharges the fluid 105 to be discharged from the outlet 103.

[0094] The free jet metering system 300 has an inlet side valve 311 which is designed to open the inlet 102 when the pump 101 draws in the fluid 104 to be dispensed, and which is designed to close the inlet 102 when the pump 101 dispenses the fluid 105 to be dispensed from the outlet 103.

[0095] The free-jet dosing system 300 includes a control unit 302. The control unit 302 can, for example, be a suitable microcontroller. The control unit 302 is connected to the free-jet dosing system 300 via a wired or wireless connection 303. The control unit 302 is preferably connected to the pump 101, the dosing monitoring device 106, and the flow sensor 110.

[0096] The control device 302 is designed to control the pump 101, the outlet-side metering monitoring device 106, and the inlet-side flow sensor 110 in such a way that both the metering monitoring device 106 and the flow sensor 110 determine the flow rate of the fluid 104, 105 flowing through the respective opening 107, 111 of the metering monitoring device 106 or the flow sensor 110 when the pump 101 draws in the fluid 104 to be delivered.

[0097] This means that during the suction stroke of pump 101, the fluid 104 located on the inlet side flows through the opening 111 of the flow sensor 110. During the suction stroke of pump 101, the valve 311 located on the inlet side opens and the fluid 104 to be discharged can flow into the pump chamber 202.

[0098] Simultaneously, the outlet-side valve 310 closes the outlet 103 during the suction stroke of the pump 101. An intact valve 310 seals the outlet 103 fluid-tight. If the outlet-side valve 310 is defective, air may be drawn in during the suction stroke of the pump 101, which can settle as a gas bubble in the nozzle chamber 205 and / or in the pump chamber 202.

[0099] When pump 101 is inactive, fluid can escape from pump chamber 202 through a leaking valve 310 and flow through outlet 103 to the metering monitoring device 106. This escaped fluid passes through opening 107 of the metering monitoring device 106, and the flow rate of this escaped fluid is determined by means of the flow meter 108. The free-jet metering system 300 can thus detect an outlet-side leakage flow.

[0100] The free-jet metering system 300 can detect not only a leakage flow from the outlet-side valve 310 during the suction stroke of the pump 101, but also a leakage flow from the inlet-side valve 311 during the pressure stroke of the pump 101.

[0101] For this purpose, the control device 302 is designed to control the pump 101, the metering monitoring device 106 and the inlet-side flow sensor 110 in such a way that both the metering monitoring device 106 and the flow sensor 110 determine the flow rate of the fluid 104, 105 flowing through the respective opening 107, 111 of the metering monitoring device 106 or of the flow sensor 110 when the pump 101 discharges the fluid 105 to be discharged from the outlet 103.

[0102] This means that when the fluid 105 is discharged, i.e., during the pressure stroke of the pump 101, the outlet-side valve 310 opens, and the fluid 105 to be discharged can flow from the pump chamber 202 towards the metering monitoring device 106 through the outlet 103, as indicated by the arrow 105. The fluid 105 to be discharged then flows through the nozzle-shaped opening 107 of the outlet-side metering monitoring device 106 and is discharged from the nozzle 107 in the form of a free jet. The flow rate of the fluid 105 to be discharged is determined by means of the flow meter 108.

[0103] Simultaneously, the inlet-side valve 311 closes the inlet 102 during the pressure stroke of the pump 101. An intact valve 311 seals the inlet 102 fluid-tight. If the inlet-side valve 311 is defective, fluid flows from the pump chamber 202 back through the inlet 102 to the inlet-side flow sensor 110. This backflowing fluid passes through the opening 111 of the flow sensor 110, and the flow rate of this backflowing fluid is determined by the flow meter 112. The free-jet metering system 300 can thus detect a leak in the inlet-side check valve 311 using the flow sensor 110.

[0104] Furthermore, the free jet metering system 300 according to the invention can detect leakage currents at the inlet-side valve 311 and / or at the outlet-side valve 310 when the pump 101 is inactive or idling, i.e., is not performing a suction stroke or a pressure stroke.

[0105] For this purpose, the control device 302 is designed to control the pump 101 and the metering monitoring device 106 and / or the flow sensor 110 in such a way that the metering monitoring device 106 and / or the flow sensor 110 determines the flow rate of the fluid 104, 105 flowing through the opening 107, 111 of the metering monitoring device 106 and / or the flow sensor 110 when the pump 101 is not operated.

[0106] When pump 101 is inactive or not actuated, there is no negative or positive pressure in pump chamber 202. The fluid to be discharged is therefore at atmospheric pressure in pump chamber 202. In this state, both the inlet-side valve 311 and the outlet-side valve 310 are fluid-tight.

[0107] Should fluid contained in pump chamber 202 nevertheless escape from pump chamber 202, this escaped fluid flows to the metering monitoring device 106 or to the flow sensor 110 and through the opening 107, 111 of the metering monitoring device 106 or the flow sensor 110, respectively. The flow rate of the escaped fluid is determined by means of the respective flow meter 108, 112.

[0108] Since the control unit 302 is aware that the pump 101 is in an inactive state, a fluid flow detected by the metering monitoring device 106 and / or the flow sensor 110 is recognized as a fault. The free-jet metering system 300 according to the invention thus receives the information that the inlet-side valve 311 and / or the outlet-side valve 310 are leaking, and which of the two valves 310, 311 is leaking. Based on the flow rate of the escaped fluid determined by means of the respective flow meter 108, 112, the respective leak rate of a leaking valve 310, 311 can be determined.

[0109] The free-jet metering system 300 can also determine the pump stroke volume during the suction stroke of the pump 101 based on the flow rate of the fluid 104 determined by the inlet-side flow sensor 110. The free-jet metering system 300 receives information about how much fluid 104 has flowed through the inlet-side flow sensor 110 and is therefore located in the pump chamber 202.

[0110] The free-jet metering system 300 can also determine the pump delivery volume during the pressure stroke of the pump 101 based on the fluid flow rate determined by the outlet-side metering monitoring device 106. The free-jet metering system 300 thus receives information about how much fluid 105 has flowed through the outlet-side metering monitoring device 106 and consequently flowed out of the pump chamber 202.

[0111] The intake volume of pump 101 during the suction stroke, measured by the inlet-side flow sensor 110, can be compared with the discharge volume measured by the outlet-side metering monitoring device 106. A discrepancy can indicate a fault. For example, if pump 101 draws in more fluid than it discharges, a leak, such as a leaking inlet-side check valve 311, can be suspected. In such a fault, a signal, e.g., "Inlet valve defective," can be generated to alert the user to the fault, or pump 101 can be automatically switched off.

[0112] For this purpose, the flow meter 108 is designed to compare the quantity or metering volume of a discharged fluid free jet 109 with a quantity or metering volume reference value and to generate a signal if the discharged quantity or metering volume is less than the quantity or metering volume reference value. As just described, the quantity or metering volume reference value can be determined based on the intake quantity measured by the flow sensor 110. However, the quantity or metering volume reference value can also be a stored value. A comparison between the actual discharged volume or the metering volume measured by the flow meter 108 with a predefined metering volume reference value can also be performed by the control unit 302.

[0113] A major advantage of the free-jet dosing system 100, 300 according to the invention is the fact that the flow measurement using the dosing monitoring device 106 is very fast, i.e., pressure fluctuations and thus also flow fluctuations can be resolved down to less than one millisecond. This has already been demonstrated metrologically (Proceedings MEMS 99, Orlando / USA, January 17-21, 1999, pp. 118-123).

[0114] This is particularly advantageous because fluctuations in pump chamber pressure and flow into and out of the pump chamber also occur very rapidly. Thanks to the very fast dosing monitoring device 106, not only can malfunctions be detected, but normal pump operation can also be continuously monitored.

[0115] Pump 101 is located in the Fig. 2A, Fig. 2B and Fig. In the embodiment shown in Figure 3, the pump is designed as an intermittently operating pump, i.e., the pump 101 generates a pressure pulse or a sequence of pressure pulses. Thus, a transient, time-varying pressure signal is present at the metering monitoring device 106 or the nozzle 107.

[0116] Detection of a previously mentioned fault, such as a leaking check valve 210, 211; 310, 311 or a blockage of the outlet nozzle 107, can be achieved by analyzing this transient signal. With a static flow, the metering monitoring device 106 cannot distinguish whether the nozzle 107 is blocked. However, the transient, time-dependent signal at the metering monitoring device 106 differs depending on whether the nozzle 107 is blocked or not. If the nozzle 107 is not blocked, the pressure pulse generated by the pump 101 will dissipate within a few milliseconds. If, on the other hand, the nozzle 107 is blocked, overpressure builds up, which cannot be released. This can be detected by a signal analysis of the metering monitoring device 106. The signal analysis can be performed by the control unit 302.

[0117] For this purpose, the flow meter 108 is designed to determine a time-varying value of the fluid pressure applied to the opening or nozzle 107 of the outlet-side metering monitoring device 106. Integrating several values ​​over time yields an actual pressure characteristic of the metering monitoring device 106 or the nozzle 107.

[0118] The opening or nozzle 107 also has a static characteristic curve or a target characteristic curve, which specifies the pressure distribution over time of the fluid flowing through it 105 as well as the flow rate. The flow meter 108 is designed to measure the time-varying fluid pressure at the opening or nozzle 107 and to send a corresponding signal to the control unit 302. The control unit 302 is designed to determine the time-dependent fluid flow through the opening or nozzle 107, according to the mathematical equations mentioned above, using the pressure signal and the knowledge of the static characteristic curve of the opening or nozzle 107. The control unit 302 is further designed to integrate this determined fluid flow over time in order to determine the volume of the fluid free jet 109 to be metered.

[0119] As mentioned at the beginning, the presence of gas bubbles in free jet dispensers is a possible source of error that can restrict the correct function of the free jet dispenser, or even lead to the total failure of the free jet dispenser.

[0120] The free jet metering system 100, 300 according to the invention can detect gas bubbles that may occur at various locations within the free jet metering system 100, 300.

[0121] Fig. Figure 4 shows a first diagram 401, in which the pump chamber pressure (y-axis) is plotted against time (x-axis), a second diagram 402, in which the flow at the inlet-side flow sensor 110 is plotted against time, and a third diagram 403, in which the flow at the outlet-side metering monitoring device 106 is plotted against time. In a first time interval I, the pump 101 is in a suction stroke. In a second time interval II, the pump 101 is in a pumping stroke or pressure stroke.

[0122] Fig. Figure 4 shows, by way of example, the time-dependent pump chamber pressure profile and the flows through the pump valves 210, 211; 310, 311, and thus through the outlet-side metering monitoring device 106 and through the inlet-side flow sensor 110 for different conditions. These conditions show a pump 101 without a gas bubble (solid line) and a pump 101 containing one or more gas bubbles (dashed line). The time-dependent flow rates measured by the metering monitoring device 106 and the flow sensor 110 are also shown.

[0123] This illustrates the situation when a voltage signal is applied to the piezoelectric element (membrane deflection element) 221, where the voltage rises and falls very rapidly. For example, if the electrical capacitance of the piezoelectric ceramic C piezoIf the capacitance is 10 nF and the charging resistance (or the internal resistance of a battery) is 1 kOhm, then the electrical voltage builds up or falls with a time constant τ = R*C = 1 kOhm*10 nF = 10 microseconds. τel=RelCpiezo

[0124] Furthermore, pressure signals can propagate very quickly. This occurs at the speed of sound, approximately 300 m / s in air or 1000 m / s in liquids or solids. With a typical pump thickness and length of 1 to 10 mm, the pressure signal spreads throughout the entire pump within a few microseconds.

[0125] The pressure signal is therefore almost as fast as the electrical signal, in any case much faster than the fluidic equalization processes.

[0126] These times are therefore very fast compared to the fluidic times in the millisecond range. Consequently, the negative pressure during the suction stroke and the positive pressure during the pressure stroke build up very quickly. During this short time, no significant compensating flow can pass through the check valves 210, 211; 310, 311. This explains the large pressure amplitude in the pump chamber 202 immediately after the voltage is switched on or off.

[0127] The pressure signals then polarize the respective valves 210, 211; 310, 311 in the flow direction or blocking direction, the valve flaps open, and fluid can flow into or out of the pump chamber 202. This equalization process can also be approximately described by a time constant, where the fluidic flow resistances R flthe microvalves 210, 211; 310, 311 (during the suction stroke essentially the resistance of the inlet valve 211; 311, during the pressure stroke that of the outlet valve 210; 310, if there are no leakage rates) and the pump chamber 202 R PK and the fluidic capacities of the drive diaphragm C M and a potential gas bubble in pump chamber C gas take effect: τfl=(Rfl+RPK)(CM+Cgas)

[0128] The presence of a gas bubble in the pump chamber 202 represents a disturbance that manifests itself (depending on the size of the gas bubble) as a greater or lesser fluidic capacitance. This has two consequences for the transient signals: the amplitude is reduced, and the compensation process for the respective pump stroke is prolonged. This effect depends on the magnitude of the fluidic capacitance and thus on the size of a gas bubble. As a result, the dosing monitoring device 106 and the flow sensor 110 can not only detect the presence of a gas bubble, but also quantify its size.

[0129] A gas bubble can therefore occur, for example, in the pump chamber 202. As described previously, a gas bubble in the pump chamber 202 causes the pressure amplitude to decrease and the pressure equalization at the nozzle 107 to take longer. To determine this, the flow meter 108 is designed to measure the amplitude of the fluid pressure at the opening or nozzle 107 of the metering monitoring device 106 when a free jet 109 is discharged, i.e., when a pump stroke is performed.

[0130] The free-jet metering system 100 is designed to compare this measured amplitude value, i.e., actual value, with an amplitude comparison value, i.e., setpoint value. This comparison can be performed, for example, by the control device 302. The amplitude comparison value is a value that corresponds to the setpoint nozzle pressure prevailing in the normal state of the pump.

[0131] The flow meter 108 is also designed to measure the time required for pressure equalization at the opening or nozzle 107. More precisely, the control device 302 measures the time within which the flow meter 108 sends a pressure equalization signal.

[0132] The free-jet metering system 100 is further configured to compare this measured time interval, i.e., actual value, with a time interval comparison value, i.e., target value. This comparison can be performed, for example, by the control device 302. The time interval comparison value is a value that corresponds to the target time interval required for pressure reduction at the nozzle 107 under normal pump operating conditions.

[0133] If the comparison reveals a deviation between the actual value and the target value, i.e., if the determined amplitude value is smaller than the amplitude comparison value and the measured time period for pressure equalization is larger than the time comparison value, the free jet dosing system 100 can conclude that a gas bubble is present in the pump chamber 202.

[0134] A gas bubble can also be present in nozzle chamber 205, for example. Depending on its size, a gas bubble in nozzle chamber 205 will compress the gas bubble through the pressure pulse, thereby reducing the pressure amplitude and delaying the rising edges.

[0135] To determine this, the flow meter 108 is designed to determine an instantaneous value of the amplitude of the fluid pressure applied to the opening or nozzle 107 of the metering monitoring device 106 when a free jet 109 is emitted, i.e. when a pump stroke is performed.

[0136] The free-jet metering system 100 is designed to compare this measured amplitude value, i.e., actual value, with an amplitude comparison value, i.e., setpoint value. This comparison can be performed, for example, by the control device 302. The amplitude comparison value is a value that corresponds to the setpoint nozzle pressure prevailing in the normal state of the pump.

[0137] The flow meter 108 is also designed to measure the time required for a pressure increase at the opening or nozzle 107. More precisely, the control device 302 measures the time within which the flow meter 108 sends a pressure increase signal.

[0138] The free-jet metering system 100 is further designed to compare the measured time interval required for the pressure increase, i.e., the actual value, with a time interval comparison value, i.e., the target value. This comparison can be performed, for example, by the control device 302. The time interval comparison value is a value that corresponds to the target time interval required for pressure build-up at the nozzle 107 under normal pump conditions.

[0139] If the comparison reveals a deviation between the actual value and the target value, i.e., if the determined amplitude value is smaller than the amplitude comparison value and the measured time period for the pressure rise is larger than the time comparison value, the free jet dosing system 100 can conclude that a gas bubble is present in the nozzle chamber 205.

[0140] As long as the pressure amplitudes are large enough to open the microvalves 210, 211; 310, 311 when a gas bubble is present, the full stroke can still be completed, it just takes a little longer. However, it is clear that if the operating frequency f = 1 / T of pump 101 becomes high enough, the delays caused by the gas bubble may prevent the pump stroke from being completed if the available time for the suction and discharge strokes becomes less than the necessary compensation processes.

[0141] This would mean that the pumped volume per cycle at this higher operating frequency is greater without a gas bubble than with one. Therefore, at high operating frequencies, the gas bubble alters the flow rate per pump cycle and thus the pumping rate. Both of these factors can be precisely detected by the metering monitoring device 106 and the flow sensor 110. The free-jet metering system 100 can therefore not only measure the reduction in flow rate but also determine its cause, namely the entry of a gas bubble into the pump chamber 202.

[0142] In Fig. 4 also indicates the case where the inlet valve 211, 311 is leaking, and during the pressure stroke only about 60% is conveyed in the correct direction per unit of time, but 40% is returned through the leaking inlet valve 211, 311.

[0143] The advantage of transient analysis is further illustrated by the following example: If pump 101 is inactive and / or if microvalves 210, 211; 310, 311 are closed, no flow should actually pass through the microdosing system 100. However, if the dosing monitoring device 106 (and / or the flow sensor 110) displays a different value compared to a previous calibration, this can have two causes: firstly, the dosing monitoring device 106 (and / or the flow sensor 110) may have drifted in the meantime, or a leakage rate may have developed in microvalves 210, 211; 310, 311 (e.g., due to particles). In the case of the inactive pump 101, the dosing monitoring device 106 (or the flow sensor 110) cannot distinguish between these possible causes. However, if the transient measurement of a leakage flow described above (i.e.If the inlet-side flow sensor 110 is detected during the pressure stroke for the inlet valve 211, 311, and the outlet-side metering monitoring device 106 is detected during the suction stroke for the outlet valve 210, 310), then the above causes can be clearly distinguished: because the drift of the metering monitoring device 106 (or the flow sensor 110) occurs on a long time scale, a corresponding sensor pulse on the millisecond time scale can therefore be assigned to a leak.

[0144] A "diagnostic routine" can also be used to determine if one of the following is present: Fig. The valves 140a, 140b (NC, NO, DNC...) shown in Figure 1B, which are connected in series, have leakage rates (e.g., due to particles). In this case, the pump 101 is activated when valve 140a, 140b is closed. If valve 140a, 140b is sealed, then no flow should pass through the metering monitoring device 106 or the flow sensor 110 during the corresponding pump stroke (depending on whether valve 140a, 140b is located in the suction line or the discharge line). If a transient signal is nevertheless detected by the metering monitoring device 106 or the flow sensor 110, a leak in the respective valve 140a, 140b can be clearly concluded.

[0145] The free-jet dosing system 100 therefore has several advantageous properties. Firstly, it is self-filling and secondly, it is relatively tolerant of gas bubbles, even at a high compression ratio of the pump 101, such as 40 bar. The check valves 210, 211; 310, 311 of the pump 101 allow free jets 109 to be emitted at a high repetition frequency of up to 500 Hz. The integrated dosing monitoring device 106 allows malfunctions to be detected and the dosing quantity to be monitored.

[0146] Besides the occurrence of gas bubbles, another problem that is not uncommon with jet dispensers is the formation of satellite droplets at the end of the free jet 109, which have a lower kinetic energy and can scatter more.

[0147] For example, to generate a defined jet break, the aforementioned transient pressure signal at the nozzle 107 can be measured by means of the flow meter 108, and the movement of the drive diaphragm 220 of the pump 101 can be abruptly stopped in the pump stroke when the pressure at the metering monitoring device 106 falls below a certain value.

[0148] Further possibilities for generating a defined jet separation can be achieved, for example, by providing a specific shape for the nozzle 107. Fig. Models 5A to 5E exhibit such different nozzle shapes.

[0149] Fig. Figure 5A shows a first nozzle shape 107A according to an embodiment of the invention. A collar 501 is formed laterally around the nozzle 107A. This collar 501 can be formed by removing a portion of the membrane 502 laterally around the nozzle 107A, for example, by suitable etching processes. Accordingly, a recess 503 is formed laterally around the nozzle 107A.

[0150] Fig. Figure 5B shows a further nozzle shape 107B according to a further embodiment of the invention. This nozzle shape 107B differs from the previously mentioned nozzle shape 107A in that the collar 501 extends radially outwards from a top surface 505 of the membrane 502 to a bottom surface 506 of the membrane 502. This results in an angled or chamfered section 504. At the upper end of the chamfered section 504, a sharp edge or point 507 is formed, at which the emerging fluid jet can be brought to a controlled separation.

[0151] Fig. Figure 5C shows another nozzle shape 107C, which, however, does not belong to the invention. This nozzle shape 107C differs from the previously mentioned nozzle shapes 107A and 107B, among other things, in that the nozzle 107C is designed as a conical nozzle. That is, the nozzle 107C tapers conically in the vertical direction, i.e., in the direction from the lower membrane surface 506 to the upper membrane surface 505. A conical nozzle 107C results in a more directional jet.

[0152] Fig. Figure 5D shows another nozzle shape 107D according to a further embodiment of the invention. This nozzle shape 107D differs from the previously mentioned nozzle shape 107C, among other things, in that the opening 508 formed on the underside 506 of the membrane has a larger diameter. Furthermore, a collar 501 is formed on the upper side 505 of the membrane, extending laterally around the nozzle 107D. The collar 501 has a first chamfer 509 and an opposing second chamfer 510. The chamfers 509 and 510 can be formed, for example, by wet chemical anisotropic etching using potassium hydroxide (KOH).

[0153] Fig. Figure 5E shows a further nozzle shape 107E according to a further embodiment of the invention. This nozzle shape 107E differs from the previously mentioned nozzle shapes 107A to 107D, among other things, in that the nozzle 107E has a hydrophobic coating 512, at least partially. The hydrophobic coating 512 is applied, among other things, at least partially, inside the nozzle 107E. The hydrophobic coating 512 can also be, as shown in Fig. 5E shown, extending over part of the collar 501 and at least partially into the laterally circumferential recess 503.

[0154] As mentioned previously, a major advantage of using the free-jet metering system 100 according to the invention is that the flow measurement is very fast; that is, flow fluctuations can be resolved in less than a millisecond. This enables the following advantageous possibilities: 1) Normal operating mode: • Consideration of normal operating mode: ◯ no gas bubble in pump chamber 202 ◯ no gas bubble in nozzle chamber 205 ◯ Valves 210, 211 intact, no leakage rates • When the stroke volume of the pump 101 is discharged through the outlet valve 210, a defined, time-dependent overpressure is generated. • This overpressure opens the outlet valve 210 • Since the metering monitoring device 106 is adapted to the outlet 103 of the pump 101 according to the invention, there are no elastic elements (e.g., soft seals or hoses) between the outlet valve 210 and the nozzle 107. This means that, in the absence of gas bubbles, the overpressure of the pump 101 is transferred directly to the nozzle 107 during discharge. Therefore, the pressure in the pump chamber 202 corresponds to the pressure at the nozzle 107. • The flow meter 108 of the dosing monitoring device 106, designed as a Wheatstone bridge, measures a very rapidly rising pressure signal at the nozzle 107 during “normal operation”. • When the jet 109 of (incompressible) liquid is ejected, the drive diaphragm 220 of the pump 101 will be able to move, accordingly the pressure in the pump chamber 202 and at the nozzle 107 will decrease. • In this “normal operation”, the time-dependent flow through the nozzle 107 can be determined from the measured, time-dependent pressure signal and the static characteristic curve of the nozzle 107. • This can be integrated over time, and the dosed volume can be determined.

[0155] Furthermore, all embodiments of the free jet dosing system 100, 300 according to the invention have the advantage that they can be calibrated in order to compensate for any drift of the dosing monitoring device 106 and / or the second flow sensor 110.

[0156] For example, if the control unit 302 ensures that no fluid flow is taking place, e.g., when the pump 101 is switched off, then the metering monitoring device 106 is "zeroed," i.e., the flow meter 108 is read, and this read value is taken as the "zero flow value," or zero point or starting point. This allows the zero point to be redefined before any or every suction and / or pressure stroke of the pump 101.

[0157] With regard to this calibration, or rather the determination of a "zero flow value," the control unit 302 is designed to detect the prevailing actual value of the sensor signal from the metering monitoring device 106 when the pump 101 is inactive and to set this as the current zero value. The control unit 302 switches the pump 101 to an inactive state, i.e., the pump 101 performs neither a suction stroke nor a discharge stroke. In this inactive state of the pump 101, no fluid to be discharged flows between the inlet 102 and the outlet 103.

[0158] However, it can happen that the sensor signal of the dosing monitoring device 106 drifts, i.e., the value of the sensor signal considered at time t1 changes over time, so that this sensor signal has a different value at a second time t2 than at the previous time t1. This can be induced, for example, by mechanical stress during the housing of low-cost sensors.

[0159] The control unit 302 can therefore acquire the current sensor value of the dosing monitoring device 106 at any given time t0 and set it as the new zero value. In other words, the current sensor value can be subtracted from the measurement signal as an offset in an immediately subsequent flow measurement of the dosing monitoring device 106 using the flow meter 108. The free-jet dosing system 100 is thus recalibrated before a measurement.

[0160] The control device 302 is configured to determine a correction value and subtract it from the amount of the detected actual sensor signal of the dosing monitoring device 106, the difference value obtained forming a corrected starting point for the subsequent sensor signals of the dosing monitoring device 106.

[0161] Therefore, if the control unit 302 detects that there is no flow (e.g., due to inactivity of pump 101 and / or closed microvalves 210, 211; 310, 311), the dosing monitoring device 106 is calibrated or "zeroed". For example, the control unit 302 can detect the current actual value of the dosing monitoring device 106 and correct it using a correction value to define the resulting signal as the current "zero flow value", zero point, or starting point.

[0162] The correction value is determined by the control unit 302 and is based on the acquired actual sensor signal from the dosing monitoring device 106. The correction value is subtracted from the acquired actual sensor signal. The resulting difference serves as a new starting point for subsequent sensor signals. In other words, the current actual sensor signal is defined as the new "zero signal." This new "zero signal" can be subtracted as an offset from the measurement signal in an immediately subsequent measurement of the flow sensor, provided the flow sensor has not yet drifted away again.

[0163] For example, the correction value can correspond to the magnitude of the measured actual sensor signal and be subtracted from it. Thus, if, for instance, an actual sensor signal of ±50 mV is measured due to sensor drift when pump 101 is inactive, a correction value of 50 mV can be subtracted from the magnitude of the actual sensor signal. That is, the magnitude of the actual sensor signal of ±50 mV is corrected by the correction value of 50 mV. The drifting sensor signal is thereby reset to zero.

[0164] The correction value can be subtracted from the previously acquired actual sensor signal before a measurement of the sensor signal of the dosing monitoring device 106 is carried out. This redefines the "zero point." However, it is also conceivable that the actual sensor value is initially stored as a correction value and only subtracted from this measured sensor signal after a measurement has been carried out. In this case, the correction value is therefore only subtracted from the obtained measured value as an offset after the measurement has been completed.

[0165] Regardless of whether the correction value is subtracted from the respective sensor signal before or after a measurement, if the sensor signal of the dosing monitoring device 106 is subject to a time-varying sensor drift, the amount of the sensor drift can be set to zero at any given time t0. The sensor drift is, in effect, suppressed or corrected at time t0, and the current zero point of the dosing monitoring device 106 at time t0 is redefined.

[0166] The correction value does not have to exactly match the magnitude of the actual sensor signal. It is also conceivable that the correction value can be any value between zero and the actual sensor signal. For example, if an actual sensor signal of ±50 mV is measured due to sensor drift, a correction value of any value between 0 mV and 50 mV can be subtracted from the magnitude of the actual sensor signal. In this case, for instance, a correction value of 49 mV could be subtracted from the magnitude of the measured actual sensor signal of ±50 mV. This would result in a new difference of 1 mV, which would then be used as the new starting point, or "zero point," for subsequent measurements.

[0167] It is also conceivable that the correction value lies within a range of the magnitude of the actual sensor signal plus a tolerance value of ±10% of the actual sensor signal or plus a tolerance value of ±20% of the actual sensor signal. Accordingly, for example, with an actual sensor signal value of ±50 mV, a correction value x1 could be selected in the range of 50 mV ±10%, i.e., 45 mV < x1 < 55 mV, or a correction value x2 in the range of 50 mV ±20%, i.e., 40 mV < x2 < 60 mV.

[0168] The control unit 302 is designed to perform the calibration of the free-jet metering system 100 before any or even every pump stroke. Accordingly, the control unit 302 can perform the calibration before a suction stroke and / or before a pressure stroke of the micropump 101, as described above.

[0169] The metering monitoring device 106 can therefore be recalibrated before each suction and / or pressure stroke of the pump 101. This counteracts any potential sensor drift of the metering monitoring device 106. Thus, even a low-cost sensor, which is not mounted using complex assembly methods and may even be housed under mechanical stress, can be used as a suitable and accurate metering monitoring device 106 for the free-jet metering system 100, 300 according to the invention. This applies both to a metering monitoring device 106 arranged on the outlet side and to a flow sensor 110 arranged on the inlet side.

[0170] Before calibrating the free-jet metering system 100, it should always be ensured that there is no free flow, or only a negligible flow, of the fluid 104, 105, 109 between inlet 102 and outlet 103 in order to adequately compensate for the drifting sensor signal. This can be ensured, among other things, by the free-jet metering system 100 having a lower pressure on the inlet side than on the outlet side, according to the invention. For example, as previously described with reference to Fig. 2A, reservoir 201, is provided, whereby the fluid level in reservoir 201 must always be kept below the fluid level in the outlet. In this consideration, it is irrelevant whether the connecting fluid-filled fluid channels are above or below the fluid level in inlet 102 or the fluid level in outlet 103. The hydrostatic pressure in reservoir 201 is insufficient to allow free fluid flow between inlet 102 and outlet 103. In this configuration, a reverse flow from outlet 103 back into inlet 102 would theoretically be possible with respect to the pressure conditions; however, the passive check valves 210, 211; 310, 311 of pump 101 (in Fig. They are polarized in the blocking direction and prevent backflow, thus ensuring that no flow (or only a negligible leakage current) occurs.

[0171] To ensure that no fluid flows through pump 101 even when it is switched off, the following must be observed. Firstly, no "free flow" may occur by ensuring that no back pressure develops. This can be achieved, for example, by ensuring that the reservoir 201 containing the fluid is always closed, as described in Fig. As shown in Figure 2A, it is located below pump 101. Furthermore, no overpressure should be exerted on reservoir 201 when pump 101 is switched off.

[0172] Furthermore, no flow should occur through closed valves 310 and 311. If the outlet pressure is higher than the inlet pressure, these valves 310 and 311 close. If the inlet pressure is higher than the outlet pressure, these valves 310 and 311 open, and free flow can occur. To prevent this, additional valves 140a and 140b can be provided. This can be achieved, for example, by designing valves 140a and 140b as one of the following types: • Active valves • NO valve that closes • NC valve • Passive valves • Safety valve • DNC valve • Microvalve with operating threshold pressure

[0173] Therefore, if the free-jet dosing system 100, 300 should have a higher pressure on the inlet side than on the outlet side, design measures can be taken to prevent free fluid flow between inlet 102 and outlet 103. According to the in Fig. In the embodiment shown in Figure 1B, an additional valve 140a, 140b can be provided. Valve 140a can be arranged on the outlet side. Alternatively, valve 140b can be arranged on the inlet side. It is also possible to have one valve 140a, 140b on both the outlet and inlet sides.

[0174] Valve 140a, 140 can be closed, thus preventing free fluid flow between inlet 102 and outlet 103. Valve 140a, 140 can be an active normally closed valve, as known, for example, from EP 1 320 686 B1. Valve 140a, 140b can be a valve with a threshold pressure that is leak-tight below a threshold pressure, as known, for example, from DE 10 2008 035 990 A1. Valve 140a, 140b can be a so-called double normally closed microvalve, as known, for example, from EP 1 576 294 B1. Valve 140a, 140b can also be a so-called safety valve, as known from EP 2 220 371 B1.

[0175] As in Fig. As shown in Figure 1B, the inlet-side valve 140b can be arranged between the pump 101 and the inlet-side flow sensor 110. Alternatively, and preferably, the inlet-side valve 140b can also be arranged upstream of the inlet-side flow sensor 110. This is preferred because it prevents an increase in dead volumes, fluidic capacitances, and fluidic inductances between the flow sensor 110 and the pump 101. The outlet-side valve 140a can be arranged as shown in Figure 1B. Fig. As shown in Figure 1B, the valve 140a is arranged between the pump 101 and the outlet-side metering monitoring device 106. Alternatively, the outlet-side valve 140a can preferably also be arranged downstream of the outlet-side metering monitoring device 106 in the flow direction.

[0176] Alternatively or in addition to the valves 140a, 140b, the pump 101 can have active inlet and outlet valves 210, 211; 310, 311 to prevent backflow of the fluid, i.e. from the outlet 103 to the inlet 102, by closing the active valves 210, 211; 310, 311.

[0177] Such a micropump with an active inlet valve and active outlet valves is known, for example, from the document DE 102 38 600 A1.

[0178] With the help of such a micropump, which has active valves, in addition to preventing the backflow of the fluid, it is also possible to prevent the forward flow of the fluid (free flow) if one of the active valves 210, 211; 310, 311 or both valves are actively closed.

[0179] Furthermore, according to embodiments of the invention, there should be no "fluidic capacitances" (e.g., soft plastic hoses or other elastic elements) between the pump 101 and the metering monitoring device 106 that would cause time delays before the flow comes to a standstill. That is, it is advantageous that there are no long, flexible lines between the pump 101 and the metering monitoring device 106.

[0180] An advantageous arrangement would be, for example, a micropump 101 with a safety valve, in which the dosing monitoring device 106 is arranged directly after the micropump 101, e.g. by gluing, clamping (over a seal), soldering the dosing monitoring device 106 or the flow sensor 110 directly onto the underside of the pump 101 at the outlet 103 or inlet 102.

[0181] According to one embodiment, the control device 302 is designed to compare the flow rate determined through the opening 107 of the metering monitoring device 106 with a predetermined flow rate comparison value and to control the pump 101 until the flow rate determined through the opening 107 of the metering monitoring device 106 is equal to or greater than the predetermined flow rate comparison value.

[0182] The free-jet metering device 100, 300 according to the invention allows the amount of fluid to be dispensed to be precisely metered. For example, if a dispensing quantity of 1.0 nl of fluid is desired, and the pump 101 can deliver a maximum of 0.25 nl per pump stroke, then the control device 302 activates the pump 101 until the desired dispensing quantity of 1.0 nl is reached. With an intermittently operating pump 101, this would require a total of four pump strokes.

[0183] The dosing monitoring device 106 described above can be made of a ceramic, but is preferably designed as a semiconductor chip, for example made of silicon. A membrane 240, 502 is embedded in the chip 106, for example by conventional etching methods ( Fig. 2A or Fig. 5A to 5E). On the membrane 240, 502, for example, four resistors 108, in particular piezoresistive resistors, are arranged in a Wheatstone bridge circuit, of which only two resistors 108 are visible in each of the cross-sectional views shown in the figures. The Wheatstone bridge circuit serves as a flow meter 108. The opening 107 provided in the metering monitoring device 106 is preferably formed in the membrane 240 and serves as a flow resistor with a defined flow resistance. The opening 107 can, for example, be introduced into the membrane 240 by dry etching.

[0184] The metering monitoring device 106 is designed to determine the amount of fluid flowing through the opening 107 by means of the flow meter 108 based on a transient, i.e., time-dependent, pressure signal. The metering monitoring device 106 measures the pressure difference between the side of the diaphragm 240 facing the pump inlet 102 or pump outlet 103 and the side of the diaphragm 240 facing away from the pump inlet 102 or pump outlet 103.

[0185] The pressure difference changes over time. For example, with a metering monitoring device 106 arranged on the outlet side, at the beginning of a pump stroke, a high initial pressure is present on the side of the diaphragm 240 facing the pump outlet 103, which is higher than the pressure present on the side of the diaphragm 240 facing away from the pump outlet 103. The rising edge of the pressure profile on the side of the diaphragm 240 facing the pump outlet 103 thus rises steeply at the beginning of the pump stroke.

[0186] As the pump stroke approaches its end, more fluid has already flowed through the opening 107 formed in the diaphragm 240. Accordingly, the overpressure on the side of the diaphragm 240 facing the pump outlet 103 decreases continuously compared to the overpressure on the side of the diaphragm 240 facing away from the pump outlet 103. The pressure profile or pressure signal therefore exhibits a decreasing slope over time.

[0187] The dosing monitoring device 106 is designed such that the time-dependent fluid flow through the nozzle 107 can be determined from the measured, time-dependent pressure signal and the static characteristic curve of the opening or nozzle 107. This fluid flow can then be integrated over time to determine the metered volume or flow rate.

[0188] Based on the pressure, the metering monitoring device 106 determines the flow rate of the fluid to be dispensed through the nozzle 107 of the metering monitoring device 106 by means of the flow rate measuring device 108.

[0189] A major advantage of the free jet dosing system 100, 300 according to the invention is the fact that the measurement of the flow is very fast, i.e. flow fluctuations can be resolved in less than a millisecond.

[0190] Some of the advantages of the free jet dosing system 100, 300 described above are listed again below for overview: • The dosing monitoring device 106 and the flow sensor 110 monitor each other • Before the suction stroke: the dosing monitoring device 106 and the flow sensor 110 are “zeroed” • Suction stroke: ◯ The filling of the pump chamber 202 through the inlet-side valve 211, 311 is measured with the inlet-side flow sensor 110. ◯ Simultaneously, the outlet-side metering monitoring device 106 measures possible leakage rates of the outlet-side valve 210, 310 by means of the flow rate measuring device 108 ◯ By integrating the signal from the dosing monitoring device 106 and the flow sensor signal from the flow sensor 110, the stroke volume can be accurately determined. • After the suction stroke: The dosing monitoring device 106 and the flow sensor 110 are reset to zero. • Pressure stroke: ◯ The discharge of the stroke volume through the outlet-side valve 210, 310 is measured with the outlet-side metering monitoring device 106. ◯ Simultaneously, the inlet-side flow sensor 110 measures possible leakage rates of the inlet-side valve 211, 311 using the flow meter 112 ◯ By integrating the signal from the dosing monitoring device 106 and the flow sensor signal from the flow sensor 110, the stroke volume can be accurately determined again. ◯ Any volume stroke differences compared to the suction stroke measurement still indicate the measurement error • After the pressure stroke: the dosing monitoring device 106 and the flow sensor 110 are reset to zero.

[0191] Advantageously, this allows not only the pump rate to be measured, but also the function of the pump drive and both valves 210, 211; 310, 311 including leak rates to be permanently monitored.

[0192] A further advantage of the free-jet metering system 100, 300 according to the invention lies in the possibility of detecting a nozzle blockage, i.e., a blockage of the nozzle 107 of the metering monitoring device 106 arranged on the outlet side. A blockage of the opening 111 of the flow sensor 110 arranged on the inlet side can also be detected. Such detection of a blockage can be carried out by transient signal analysis, as described above.

[0193] In the case of static flow, the metering monitoring device 106 or the flow sensor 110 (or the control device 302 connected to the metering monitoring device 106 and the flow sensor 110) cannot distinguish whether the respective opening 107, 111 is blocked. However, the transient, time-dependent signal at the opening 107 of the metering monitoring device 106 or at the opening 111 of the flow sensor 110 differs depending on whether the opening 107, 111 is blocked or not.

[0194] If the opening 107, 111 is not blocked, the pressure pulse generated by the pump 101 will dissipate within a few milliseconds. However, if the opening 107, 111 is blocked, overpressure builds up, which cannot escape. This can be detected by signal analysis of the dosing monitoring device 106 or the flow sensor 110.

[0195] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, so that a block or component of a device can also be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device. Some or all of the process steps can be performed by (or using) a hardware apparatus, such as a time-resolved sample-and-hold data acquisition system, a microprocessor, a programmable computer, or an electronic circuit.In some embodiments, some or more of the most important process steps can be carried out by such an apparatus.

[0196] Depending on specific implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation can be carried out using a digital storage medium, for example, a floppy disk, DVD, Blu-ray disc, CD, ROM, PROM, EPROM, EEPROM, FLASH memory, hard disk, or other magnetic or optical storage medium, on which electronically readable control signals are stored. These control signals can interact with, or interact with, a programmable computer system in such a way as to execute the respective method. Therefore, the digital storage medium can be computer-readable.

[0197] Some embodiments according to the invention therefore include a data carrier which has electronically readable control signals which are able to interact with a programmable computer system in such a way that one of the methods described herein is carried out.

[0198] In general, embodiments of the present invention can be implemented as a computer program product with a program code, wherein the program code is effective in carrying out one of the methods when the computer program product runs on a computer.

[0199] The program code can also be stored on a machine-readable medium, for example.

[0200] The time-resolved data acquisition from the flow sensors, the data processing, the control of the micropump, the generation of the necessary high voltage for the e.g. piezo- or electrostatically driven micropump, and the control algorithms can, for example, be housed on an ASIC (application-specific integrated circuit), thus enabling the entire microdosing system – micropump, flow sensors, control unit, and ASIC – to be integrated into the smallest possible space (e.g., 10 × 10 × 2 mm). 3 ) can be realized.

[0201] Other embodiments include a computer program for carrying out one of the methods described herein, wherein the computer program is stored on a machine-readable medium. In other words, an embodiment of the method according to the invention is thus a computer program that includes program code for carrying out one of the methods described herein when the computer program is executed on a computer.

[0202] Another embodiment of the methods according to the invention is therefore a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for carrying out one of the methods described herein is recorded.

[0203] Another embodiment of the method according to the invention is thus a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or sequence of signals can be configured, for example, to be transferred via a data communication connection, such as the Internet.

[0204] Another embodiment comprises a processing device, for example a computer or a programmable logic device, which is configured or adapted to perform one of the methods described herein.

[0205] Another embodiment comprises a computer on which the computer program for performing one of the procedures described herein is installed.

[0206] Another embodiment of the invention comprises a device or system designed to transmit a computer program for carrying out at least one of the methods described herein to a receiver. The transmission can be, for example, electronic or optical. The receiver can be, for example, a computer, a mobile device, a storage device, or a similar device. The device or system can, for example, include a file server for transmitting the computer program to the receiver.

[0207] In some embodiments, a programmable logic device (for example, a field-programmable gate array, an FPGA) can be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field-programmable gate array can interact with a microprocessor to perform one of the methods described herein. Generally, in some embodiments, the methods are performed by any hardware device. This can be general-purpose hardware such as a computer processor (CPU) or method-specific hardware such as an ASIC.

[0208] The embodiments described above merely illustrate the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be obvious to other people skilled in the art. Therefore, it is intended that the invention be limited only by the scope of protection set forth in the following claims and not by the specific details presented herein by way of description and explanation of the embodiments.

Claims

[1] Free jet metering system (100, 300) for metering a fluid free jet (105, 109) to be delivered, comprising: a pump (101) having an inlet (102) and an outlet (103), which is designed to pump fluid (104, 105) to be discharged to the outlet (103), a metering monitoring device (106) arranged on the outlet side of the pump (101), wherein the metering monitoring device (106) has an opening (107) through which at least a part of the fluid (105) to be dispensed can pass, and wherein the metering monitoring device (106) has a flow meter (108) configured to determine the flow rate of the fluid (105) passing through the opening (107) of the metering monitoring device (106), wherein the opening (107) of the metering monitoring device (106) is designed as an outlet nozzle (107) for ejecting the fluid free jet (109), and wherein the outlet nozzle (107) has a laterally circumferential collar (501). [2] Free jet metering system (100, 300) according to claim 1, wherein the outlet nozzle (107) is formed in a membrane (502) of the metering monitoring device (106), and the laterally circumferential collar (501) is formed as a recess (503) etched laterally around the outlet nozzle (107) in the membrane (502) of the metering monitoring device (106). [3] Free jet dosing system (100, 300) according to claim 2, wherein the dosing monitoring device (106) is designed as a semiconductor chip made of silicon, and wherein the membrane (502) is designed as a membrane (502) formed in the semiconductor chip (106). [4] Free jet metering system (100, 300) according to one of the preceding claims, wherein the outlet nozzle (107) of the metering monitoring device (106) is designed as a conical nozzle. [5] Free jet metering system (100, 300) according to one of the preceding claims, wherein the outlet nozzle (107) of the metering monitoring device (106) has at least a section of a hydrophobic coating (512), wherein the hydrophobic coating (512) is applied at least section of the outlet nozzle (107). [6] Free jet metering system (100, 300) according to one of the preceding claims, wherein the metering monitoring device (106) is arranged directly at the outlet (103) of the pump (101), wherein no elastic elements, in particular seals or hoses, are located between an outlet valve (210) provided at the outlet (103) and the outlet nozzle (107). [7] Free jet metering system (100, 300) according to one of the preceding claims, wherein the pump (101) has a check valve (210, 310) on the outlet side, which is configured to close the outlet (103) when the pump (101) draws in the fluid (104) to be dispensed, and to open the outlet (103) when the pump (101) dispenses the fluid (105) to be dispensed from the outlet (103). [8] Free jet metering system (100, 300) according to one of the preceding claims, wherein the free jet metering system (100, 300) has a nozzle chamber (205) arranged between the outlet (103) of the pump (101) and the outlet nozzle (107) and a check valve (210, 310) is arranged between the pump outlet (103) and the nozzle chamber (205). [9] Free jet metering system (100, 300) according to one of the preceding claims, wherein the pump (101) has a pump chamber (202), and wherein the free jet metering system (100, 300) has a nozzle chamber (205) arranged between the outlet (103) of the pump (101) and the outlet nozzle (107) and a control device (302) configured to control the flow meter (108) and the pump (101) such that the flow meter (108) detects a fluid flow from the nozzle chamber (205) to the pump chamber (202) when the pump (101) draws in the fluid (104) to be dispensed. [10] Free jet metering system (100, 300) according to one of the preceding claims, wherein the pump (101) has a check valve (211, 311) on the inlet side, which is configured to close the inlet (102) when the pump (101) discharges the fluid (105) to be dispensed, and to open the inlet (102) when the pump (101) draws in the fluid (104) to be dispensed. [11] Free jet metering system (100, 300) according to one of the preceding claims, wherein the free jet metering system (100, 300) has a control device (302) configured to determine a time-varying value of a fluid pressure applied to the outlet nozzle (107) of the outlet-side metering monitoring device (106) and to determine the time-dependent fluid flow through the outlet nozzle (107) by means of the determined time-varying fluid pressure applied to the outlet nozzle (107) and the static characteristic curve of the outlet nozzle (107), and to integrate this fluid flow determined in this way over time in order to determine the volume of the fluid free jet (109) to be metered. [12] Free jet metering system (100, 300) according to one of the preceding claims, wherein the free jet metering system (100, 300) has a control device (302) configured to compare a quantity of a delivered fluid free jet (109) determined by means of the flow meter (108) with a quantity comparison value and to generate a signal when the delivered quantity is less than the quantity comparison value. [13] Free jet metering system (100, 300) according to one of the preceding claims, wherein the control device (302) is configured to determine a value of the amplitude of the fluid pressure applied to the outlet nozzle (107) of the metering monitoring device (106) when a fluid free jet (109) is discharged and to compare it with an amplitude reference value and / or to measure the time interval required for pressure equalization at the outlet nozzle (107) and to compare it with a time reference value in order to detect a gas bubble in the pump chamber (202) of the pump (101) if the determined amplitude value is smaller than the amplitude reference value and / or the measured time interval for pressure equalization is greater than the time reference value. [14] Free-jet metering system (100, 300) according to one of the preceding claims, wherein the free-jet metering system (100, 300) has a nozzle chamber (205) arranged between the pump outlet (103) and the outlet nozzle (107), and wherein the control device (302) is configured to determine, when a fluid free jet (109) is discharged, a value of the amplitude of the fluid pressure applied to the outlet nozzle (107) of the metering monitoring device (106) and to compare it with an amplitude reference value, and / or to measure the time interval required for a pressure increase at the outlet nozzle (107) and to compare it with a time reference value, in order to detect a gas bubble in the nozzle chamber (205) if the determined amplitude value is smaller than the amplitude reference value and / or the measured time interval for the pressure increase is greater than the Time-comparative value. [15] Free jet metering system (100, 300) according to one of the preceding claims, wherein the free jet metering system (100, 300) has an inlet-side and / or outlet-side valve (140a, 140b), wherein the valve (140a, 140b) is an active normally closed valve and / or an active normally open valve and / or a valve with threshold pressure that is closed below a threshold pressure and / or a normally double closed microvalve and / or a safety valve. [16] Free jet metering system (100, 300) according to one of the preceding claims, wherein the free jet metering system (100, 300) has a flow sensor (110) having an opening (111) and a flow meter (112), wherein the flow meter (112) is designed to determine the flow rate of the fluid (104) passing through this opening (111), wherein the flow sensor (110) is arranged on the inlet side at the inlet (102) of the pump (101) and the metering monitoring device (106) is arranged on the outlet side at the outlet (103) of the pump (101). [17] Free-jet metering system (100, 300) according to claim 16, wherein the free-jet metering system (100, 300) comprises a control device (302) configured to control the pump (101), the metering monitoring device (106), and the inlet-side flow sensor (110) such that both the metering monitoring device (106) and the flow sensor (110) determine the flow rate of the fluid (104, 105) flowing through the respective opening (107, 111) of the metering monitoring device and the flow sensor (110) when the pump (101) draws in the fluid (104) to be dispensed, and wherein the control device (302) is further configured to compare the flow rate determined by the metering monitoring device (106) and the flow rate determined by the flow sensor (110) with each other. compare. [18] Free-jet metering system (100, 300) according to claim 16 or 17, wherein the free-jet metering system (100, 300) comprises a control device (302) configured to control the pump (101), the metering monitoring device (106), and the inlet-side flow sensor (110) such that the metering monitoring device (106) and the flow sensor (110) determine the flow rate of the fluid (104, 105) flowing through the respective opening (107, 111) of the metering monitoring device (106) and the flow sensor (110) when the pump (101) discharges the fluid (105) to be dispensed from the outlet (103), and wherein the control device (302) is further configured to control the flow rate determined by the metering monitoring device (106) and the to compare the flow rates determined by the flow sensor (110). [19] Free jet metering system (100, 300) according to one of the preceding claims, wherein the pump (101) is a micropump. [20] Free jet metering system (100, 300) according to one of the preceding claims, wherein the pump (101) has a pump chamber (202) arranged between the inlet (102) and the outlet (103), a diaphragm (220) arranged at least partially in the region of the pump chamber (202) and a diaphragm deflection means (221), wherein the diaphragm deflection means (221) is configured to deflect the diaphragm (220) such that the volume of the pump chamber (202) is increased to inject the fluid (104) to be dispensed, and the volume of the pump chamber (202) is decreased to discharge the fluid (105). [21] Free jet metering system (100, 300) according to claim 20, wherein the membrane deflection means (221) is a piezoelectric element configured to deflect the membrane (220) depending on the voltage applied to the piezoelectric element (221). [22] Free jet metering system (100, 300) according to one of the preceding claims, wherein the flow metering device (108) is designed as a Wheatstone measuring bridge having piezoresistive resistors.

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