Dosing system having an adjustable actuator

Abstract

The invention relates to a dosing system (1) for a dosing material, which dosing system (1) comprises a housing (11) having a nozzle (60) and a feed channel (64) for the dosing material, a discharge element (51) arranged in the housing (11) for discharging dosing material out of the nozzle (60), at least one first actuator (20) coupled to the discharge element (51) and / or the nozzle (60), preferably a piezoactuator (20), and at least one second actuator (30) coupled to the first actuator (20), preferably an expansion material element (30). The second actuator (30) is designed to adjust a position of the at least one first actuator (20) relative to the housing (11), in particular in relation to the discharge element (51) and / or the nozzle (60). The invention also relates to a method for controlling such a dosing system (1).

Description

[0001] The invention relates to a metering system for a metering substance, comprising a housing with a nozzle and a feed channel for the metering substance, an ejection element arranged in the housing for ejecting the metering substance from the nozzle, at least one first actuator coupled to the ejection element and / or the nozzle, preferably a piezoelectric actuator, and at least one second actuator coupled to the first actuator, preferably a thermal expansion element. The invention further relates to a method for operating such a metering system.

[0002] Dispensing systems of the type mentioned above are typically used to apply a dispensed medium to a target surface in a targeted manner, i.e., at the right time, in the right place, and in a precisely measured quantity. This can be achieved, for example, by dispensing a dispensing agent drop by drop through a nozzle of the dispensing system. In so-called "micro-dispensing technology," it is often necessary to place very small quantities of the dispensing agent precisely and without contact, i.e., without direct contact between the dispensing system and the target surface. A typical example of this is the dispensing of adhesive dots, solder pastes, etc., during the assembly of printed circuit boards or other electronic components, or the application of converter materials for LEDs.

[0003] Such a contactless method is often referred to as a "jet method." A metering valve operating according to the jet method is usually called a "jet valve" or "jetting valve." Accordingly, a metering system that has at least one such jet valve and possibly other components can be called a "jetting metering system." To dispense the medium from a jetting metering system or jet valve, a movable ejector element, such as a plunger, can be arranged in the nozzle of the metering system. To eject the metering medium, the ejector element inside the nozzle can be pushed forward at relatively high speed in an ejection direction toward a nozzle opening, thereby ejecting a single droplet of the medium from the nozzle. This process is generally referred to, and will be referred to, as the ejection process. Subsequently, the ejector element can be retracted in the opposite retraction direction.The size of the droplets or the amount of medium per droplet can be predicted as precisely as possible through the design and control of the nozzle and the resulting effect.

[0004] Characteristically – and preferably also within the scope of the present invention – in a jet metering system or jet valve, the metering substance is "actively" ejected from the nozzle by an ejection movement of the ejection element relative to the nozzle. During the ejection process, in particular, an ejection tip of the ejection element comes into contact with the metering substance to be dispensed and "pushes" or "pushes" the metering substance out of the nozzle of the metering system due to the ejection movement of the ejection element and / or the nozzle. This distinguishes a jet metering system from other dispenser systems in which a movement of a closure element merely leads to the opening of the nozzle, with a pressurized metering substance then exiting the nozzle spontaneously. This is the case, for example, with fuel injectors of internal combustion engines.

[0005] Alternatively or additionally to the movable ejection element, the nozzle of the metering system, e.g., the nozzle of a jet valve, can itself be moved in an ejection or retraction direction to dispense the metering material. For dispensing the metering material, the nozzle and an ejection element located inside the nozzle can be moved relative to each other, either towards or away from each other. This relative movement can be achieved either solely by moving the nozzle or at least partially by a corresponding movement of the ejection element.

[0006] To achieve the highest possible dosing accuracy in the operation of a dosing system, e.g., a jet dosing system, a constant relative movement between the ejector and the nozzle is required. The amount of metering material dispensed from the nozzle during each ejection depends in particular on the (hydraulically) effective stroke of the ejector and / or the nozzle, i.e., the distance the ejector travels relative to the nozzle during each ejection movement.

[0007] The smaller the (hydraulically) effective stroke of a dispensing system, the more important the precise arrangement of the dispensing element and the nozzle relative to each other within the system becomes. This is especially true for piezoelectrically operated dispensing systems, where the effective stroke of the dispensing element and / or the nozzle is comparatively small, for example, compared to dispensing systems with pneumatic actuators. Therefore, particularly with piezoelectric actuator systems, one of the most important tasks is the precise setup of the entire system, i.e., adjusting the position between the dispensing element and the nozzle.

[0008] While piezoelectrically operated dosing systems can be set up or adjusted for the first time before delivery to a customer, for example, the piezo actuator and the ejection element, as well as any other components, can be arranged and adjusted at the factory within the dosing system so that a deflection of the piezo actuator causes a specific relative movement of the ejection element with respect to the nozzle, in order to eject a desired quantity of dosing material during the ejection movement.

[0009] WO 2019 / 057542 A1 describes a dispensing system with a piezoelectric stack arranged in an actuator chamber of the dispensing system. A spherical cap, height-adjustable by a screw mechanism, serves as the upper support for the piezoelectric stack. US 2015 / 0300748 A1 describes a dispensing system with two piezoelectric actuators arranged in a housing. Above the two piezoelectric actuators are two adjustment units, each in the form of a setscrew screwed to the housing, which each contact one piezoelectric actuator. US 2016 / 0136661 A1 describes a dispensing system with two piezoelectric actuators in a housing, wherein each piezoelectric actuator is assigned a position adjuster. The two position adjusters are implemented by means of screw connections and can be screwed more or less deeply into the housing.

[0010] However, it has been shown that this one-time adjustment of the dosing system is often insufficient to achieve consistently high dosing accuracy during continuous operation. Depending on the operating conditions of the dosing system, significant deviations may therefore occur between the desired target quantity and the actual quantity of dosing material dispensed.

[0011] This can be due, firstly, to the fact that the frequency of the metering agent delivery, i.e., the actuator frequency, can fluctuate considerably during operation depending on the metering requirements. The varying load conditions of the actuator, particularly in the case of piezoelectric actuators, can lead to different power losses, and the temperature of the piezoelectric actuator can fluctuate. This can subsequently lead to thermal expansion of the piezoelectric actuator and potentially other components of the metering system. Due to the coupling between the piezoelectric actuator and the ejector element, the thermal expansion of the piezoelectric actuator can also undesirably alter the (hydraulically) effective stroke of the ejector element, thus affecting metering accuracy.

[0012] Secondly, the moving components of the dosing system can be subject to wear and tear during operation. For example, the ejection tip of the dispensing element can wear down, at least in certain areas, due to frequent contact with the nozzle, to such an extent that the desired (hydraulically) effective stroke of the dispensing element is no longer reliably achieved. This, too, can change the amount of metered material dispensed.

[0013] Furthermore, it may be necessary from time to time to replace worn components of the dosing system, such as a worn ejector element. To maintain high dosing accuracy after replacement, the dosing system must be readjusted. This relatively complex process is often not performed with the necessary precision by the user of the dosing system, which can lead to undesirable changes in the required dosing process.

[0014] However, as mentioned at the outset, highly precise metering of the dosage substance is particularly desirable in microdosing technology. It is therefore an object of the present invention to reduce the previously described adverse effects.

[0015] This problem is solved by a dosing system according to claim 1 and by a method for controlling such a dosing system according to claim 7.

[0016] A metering system according to the invention for a liquid to viscous metering substance comprises a housing, the housing having a nozzle with a nozzle opening and a feed channel for supplying the metering substance to the nozzle. An ejection element for ejecting the metering substance from the nozzle and at least one first actuator coupled to the ejection element and / or the nozzle are arranged in the housing of the metering system. Preferably, the first actuator can be a piezoelectric actuator, in particular a controllable piezoelectric stack, although other types of actuators are also conceivable in principle. Particularly preferably, the first actuator can be a piezoelectric stack hermetically encapsulated in an actuator housing. For the sake of clarity, the invention will be explained below using a piezoelectrically operated metering system, i.e., assuming the first actuator is a piezoelectric actuator.

[0017] The dispensing of the metering agent from the metering system according to the invention can be carried out according to one of the principles explained above. Accordingly, as is usually the case, a ejection element movable at a relatively high speed can be arranged in the nozzle of the metering system (particularly in the area of ​​the nozzle, e.g., shortly before an outlet opening) for ejecting the metering agent from the nozzle. Alternatively or additionally, as mentioned, the outlet opening, i.e., e.g., the nozzle, of the metering system can be designed to be movable. In the following, it is assumed that the metering agent is dispensed by means of a movable ejection element, as is preferred, e.g., with a plunger. However, the invention is not intended to be limited to this.

[0018] The dosing system according to the invention can particularly preferably operate according to the "jet method". In particular, the dosing system can therefore comprise at least one jet valve. In this regard, reference is made to the definition given at the outset.

[0019] The first actuator of the metering system is functionally coupled, at least temporarily, to the dispensing element or nozzle. This coupling is such that the forces and movements exerted by the first actuator are transmitted to the dispensing element (or nozzle) in such a way that a desired, preferably vertical, movement of the dispensing element and / or nozzle results, dispensing the metering material from the nozzle. The first actuator can act directly on the dispensing element, i.e., without any further motion-mediating components. However, it is preferred that the metering system includes a movement mechanism to transmit a deflection of the first actuator to the dispensing element over a certain distance (i.e., indirectly). This will be explained later.

[0020] According to the invention, the housing of the dosing system contains at least one further second actuator, which is coupled to the first actuator, in particular to the piezoelectric actuator. The second actuator is configured to adjust the position of the first actuator, for example, the piezoelectric stack encapsulated in an actuator housing, relative to the housing, particularly with respect to the ejection element and / or the nozzle. The first and second actuators can be controlled separately for this purpose. The second actuator can therefore also be referred to as a positioning actuator for positioning the first actuator, which is coupled to the ejection element and / or the nozzle. The coupling can be such that the positioning actuator merely rests against and / or on top of the first actuator. This means that the positioning actuator is in operative contact with the first actuator, but a rigid connection between the two components is not necessarily required.The positioning actuator can, in principle, be any type of actuator, e.g., a controllable piezo actuator, for example, a piezo stack encapsulated in its own actuator housing, a shape memory actuator, a magnetistractive actuator, or similar. Preferably, the second actuator is a different type than the first, since the second actuator does not need to operate at such high expansion rates as the first.

[0021] Preferably, the positioning actuator can comprise at least one expansion element. Particularly preferably, the second actuator can be implemented by means of an expansion element. Accordingly, the expansion element can be configured to set the position of the at least one first actuator relative to the housing, particularly with respect to the ejection element and / or the nozzle. The advantage of such an expansion element lies in a better ratio between overall height (and also volume) and usable maximum stroke at comparable operating forces. The invention is described below, without limitation, using a second actuator implemented by means of an expansion element. That is, unless otherwise stated, the first actuator (for moving the plunger and / or the nozzle) will, within the scope of this application, be referred to only briefly as "actuator".The first is called a "piezo actuator", with the second (positioning) actuator being referred to as a "expansion element" without loss of generality.

[0022] A thermal expansion element, or thermal expansion working element, is, according to the general definition, an actively expandable element containing a thermal expansion material, e.g., filled with such a material, which can also be described as a "thermal expansion actuator." In addition to the thermal expansion material, the thermal expansion element can include other components, such as a housing enclosing the material and a working piston, as will be explained later. As is generally the case, the thermal expansion material is preferably designed such that a change in its temperature leads to a change in its volume. By appropriately designing the thermal expansion element, a specific or directed movement (a stroke) can be generated via this change in the volume of the thermal expansion material. The extent of the generated movement can (as is typical) be approximately proportional to the change in the volume of the thermal expansion material.

[0023] To generate a specific stroke using the expansion element, the expansion element can be controlled and / or regulated via a control unit of the metering system. According to the invention, the temperature of the expansion element is specifically controlled and / or regulated for this purpose. Further details regarding the expansion element and the control unit will be provided later.

[0024] According to the invention, the expansion element is designed and arranged in the metering system such that a specific position of the (first) actuator relative to the housing of the metering system can be set. This means that a desired spatial arrangement of the actuator, in particular the piezo actuator, within the housing can be achieved by means of the expansion element. In particular, the position of the actuator in the housing can be actively changed during operation by means of the expansion element, e.g., during a respective ejection movement and / or a respective retraction movement of the ejector. In other words, the actuator can be moved within the housing, at least to a limited extent, by the expansion element.

[0025] Preferably, the expansion element is arranged in the metering system in such a way that the stroke generated by the expansion element is predominantly transferred completely to the actuator, in particular the piezo actuator, and can be used to position the actuator.

[0026] The expansion element is specifically designed and arranged in the metering system to adjust the position of the (first) actuator, particularly the piezoelectric actuator, relative to the ejection element and / or the nozzle of the metering system. Particularly preferably, the expansion element can be used to adjust and / or change the position of a pressure piece of the actuator, which transmits the forces generated by the actuator (directly or indirectly) to the ejection element and / or the nozzle. For example, depending on the specific design of the metering system, a specific distance between the pressure piece of the actuator and a nozzle opening can be set using the expansion element. Similarly, a distance between the pressure piece of the actuator and the ejection element can also be set.

[0027] Advantageously, the expansion element allows for the setting of a specific target arrangement between the (first) actuator and the ejection element or nozzle, so that a precisely determined quantity of metering material is ejected from the nozzle by means of a respective deflection of the actuator. The metering system according to the invention thus comprises, with the expansion element, an additional actuating element for the "pinpoint" positioning of the actuator in the housing, so that, for example, the high dynamics of the piezo actuator can be used almost completely for the actual metering function of the metering system.

[0028] A particular advantage is that such a target arrangement or position of the actuator can be kept largely constant even during operation of the dosing system. The expansion element can be used, on the one hand, to fulfill thermal compensation functions, also known as "thermal compensation." For example, thermal length changes of the actuator, especially the piezo actuator, that occur during operation can be compensated for by operating the expansion element in the opposite direction, so that the position of the actuator relative to the ejection element and / or the nozzle can be kept constant during operation.

[0029] On the other hand, the expansion element can also fulfill mechanical compensation functions, e.g., to compensate for operational wear of components of the dosing system. For example, the actuator, especially the piezo actuator, can be routinely (re)positioned in the housing during operation using the expansion element so that the target arrangement remains largely constant despite wear and tear, particularly of moving components (such as the ejection element).

[0030] Furthermore, the expansion element can also be advantageously used to (re)adjust the overall system correctly after a temporary interruption of the dosing operation. This makes it possible, for example, to replace only a worn component of the dosing system, such as a plunger, instead of an entire assembly. Restoring the correct configuration can then be achieved using the expansion element. Therefore, the wear-related costs of the dosing system according to the invention can be reduced compared to known dosing systems.

[0031] Due to the advantageous effects explained above, the dosing accuracy of the dosing system according to the invention can be significantly improved compared to known dosing systems.

[0032] In a method according to the invention for controlling a metering system for a liquid to viscous metering substance, the metering system comprises a housing, the housing having a nozzle and a feed channel for the metering substance. The metering system further comprises an ejection element arranged in the housing for ejecting metering substance from the nozzle, at least one first actuator coupled to the ejection element and / or the nozzle, preferably a piezoelectric actuator, and at least one second actuator coupled to the first actuator, preferably a thermal expansion element. The second actuator is controlled and / or regulated by a control unit such that a position of the at least one first actuator relative to the housing, in particular with respect to the ejection element and / or the nozzle, is set.

[0033] To position the (first) actuator in the housing, the expansion length of the expansion element can be controlled and / or regulated in at least one direction. Preferably, the expansion length of the expansion element can be controlled and / or regulated via its temperature. This will be explained in more detail later.

[0034] Further, particularly advantageous embodiments and developments of the invention result from the dependent claims and the following description, wherein the independent claims of a claim category may also be further developed analogously to the dependent claims and embodiments of another claim category, and in particular individual features of different embodiments or variants may be combined to form new embodiments or variants.

[0035] The second actuator, in particular the expansion element, is preferably designed and arranged in the housing to adjust the position of the ejection element relative to the nozzle of the metering system via the position of the (first) actuator, in particular the piezo actuator. Specifically, the expansion element allows the distance between an ejection tip of the ejection element and a nozzle opening of the nozzle to be adjusted via the position of the (first) actuator.

[0036] In a corresponding method for controlling the metering system, the second actuator, in particular the expansion element, can therefore be controlled and / or regulated such that a position of the ejection element is set relative to the nozzle of the metering system. Preferably, the expansion element can be controlled and / or regulated such that a specific distance between the ejection tip of the ejection element and the nozzle opening is set via the position of the (first) actuator, in particular the piezoelectric actuator.

[0037] In a preferred method for controlling the dosing system, the control and / or regulation of the second actuator, in particular the expansion element, can be carried out such that a temperature of the second actuator, preferably of the expansion element, and in particular a temperature of the expansion material, is controlled and / or regulated. Preferably, at least one heating device and / or at least one cooling device associated with the expansion element can be controlled and / or regulated for this purpose, as will be explained later. Particularly preferably, a temperature of the expansion element can be set such that a specific stroke of the expansion element is generated in order to position the actuator, in particular the piezoelectric actuator, and / or the ejection element in a specific position in the housing.

[0038] As mentioned, the ejection element can preferably be coupled to the (first) actuator, in particular the piezoelectric actuator, by means of a movement mechanism. The ejection element is also referred to synonymously as a plunger. The invention is described below, without limitation, using a metering system with a movement mechanism as an example. The movement mechanism can include a coupling element to transmit the movements of the actuator to the ejection element. The coupling between the actuator, or the piezoelectric actuator, in particular its pressure piece, and the movement mechanism and / or between the movement mechanism and the ejection element is preferably not a fixed coupling; that is, the respective components are preferably not screwed, welded, glued, etc., together for coupling purposes.

[0039] Preferably, the coupling element can include a transmission element, e.g., a lever system with a tiltable lever or the like, to increase the actuator's displacement by a specific factor. In particular, the transmission element can be configured to generate a specific transmission ratio between the actuator's displacement or stroke and the resulting movement or stroke of the plunger. This means, on the one hand, that the transmission element can translate the displacement of the (first) actuator into a specific, desired stroke of the plunger.

[0040] On the other hand, the translation element can also be advantageously used to transmit a change in position of the (first) actuator, preferably caused by the expansion element, to the ejection element to a greater extent. This means that a comparatively small change in the actuator's position by the expansion element can result in a relatively large change in the position of the ejection element.

[0041] The second actuator, in particular the expansion element, is preferably designed and arranged in the housing to move the ejection element to a suitably defined "adjust position" during a defined operating state of the metering system. The operating state preferably corresponds to the maximum possible deflection of the (first) actuator, in particular the piezoelectric actuator, as provided for during operation. Preferably, a change in the position of the (first) actuator can be transmitted to the ejection element via the movement mechanism to set the "adjust position".

[0042] The "adjust position" is preferably characterized or defined here by the fact that the ejection element, in particular the ejection tip of the plunger, is pressed into the nozzle with a specific force. The force exerted by the plunger on the nozzle in the adjust position is referred to as the indentation force or sealing force. In the adjust position, the plunger can be pressed into a sealing seat of the nozzle such that a sealing area of ​​the nozzle is preferably completely filled by the plunger. The sealing area is understood to be an area in the sealing seat of the nozzle that is directly adjacent to the nozzle opening inside the nozzle (nozzle chamber). In the sealing area, the plunger and the nozzle can interact to create a seal, in particular by pressing the plunger against the sealing seat.

[0043] Preferably, in the adjust position, the plunger generates a specific sealing force against the nozzle. The sealing force of the ejection element can be, for example, at least 1 mN, preferably at least 1 N, and preferably at least 10 N.

[0044] In a preferred method for controlling the metering system, the second actuator, in particular the expansion element, can therefore be controlled and / or regulated such that the ejection element is moved into the adjust position during the defined operating state of the metering system. Preferably, the expansion element can be controlled and / or regulated such that the ejection tip of the ejection element is pressed against the nozzle with a specific sealing force at a maximum deflection of the piezoelectric actuator intended during operation.

[0045] Advantageously, the adjustable position of the ejector element allows for the precise setting and maintenance of a hydraulically effective stroke of the plunger, further improving the dosing accuracy of the dosing system. This is explained below.

[0046] In a preferred method for controlling the metering system, the deflection of the (first) actuator (actuator deflection), in particular the electrical control voltage applied to the piezoelectric actuator, during each ejection process can be used, on the one hand, to move the plunger from an initial ejection position towards the nozzle until "full contact" is achieved. Full contact is defined as the ejection tip of the plunger coming into effective contact with the nozzle, preferably completely circumferentially. In particular, at full contact, the plunger can rest against the nozzle's sealing seat in such a way that the nozzle opening is closed.

[0047] The stroke (the distance traveled) that the plunger executes during each ejection process until full contact with the nozzle is referred to as the "hydraulically effective stroke" of the plunger. The hydraulically effective stroke is therefore a portion of the maximum actuator deflection intended for operation, or a portion of the maximum electrical control voltage applied to the piezo actuator during operation, that can be used for ejecting the metering fluid and thus influences the metering fluid delivery.

[0048] On the other hand, the actuator deflection can also be used, at least in part, to push the plunger further towards the nozzle beyond full contact. This defined portion of the total actuator deflection, or the portion of the maximum intended electrical control voltage of the piezo actuator, by which the plunger is pushed a certain minimum distance further towards the nozzle from full contact, is referred to as the sealing-position actuator deflection, as will be explained later. Preferably, a specific sealing force of the plunger can be generated by means of the sealing-position actuator deflection.

[0049] In an "ideal" very rigid metering system, the plunger's position after full contact can remain largely constant even with progressive actuator deflection or a further increase in the electrical control voltage applied to the piezoelectric actuator (piezoelectric actuator control voltage). This means that the plunger is pressed against the nozzle with increasing force by means of the sealing-position actuator deflection, thereby generating a specific sealing force.

[0050] Depending on the design of the dispensing system, e.g., the properties of the materials used, the sealing actuator deflection can also lead to a slight elastic deformation of components within the dispensing system. For example, the nozzle insert, the plunger, connecting elements of the fluidic unit such as the lever, or a combination of these or other components can be elastically deformed. Accordingly, in an "ideal," non-rigid dispensing system, the plunger's position may still change slightly after full contact due to the ongoing actuator deflection or the increase in the piezoelectric actuator control voltage, particularly in the nanometer or micrometer range. However, even in such a non-rigid dispensing system, a large portion of the sealing actuator deflection can preferably be transferred to the plunger and used to adjust the plunger's sealing force.

[0051] Regardless of the specific design of the dosing system, a maximum deflection of the actuator intended during operation, in particular a maximum control voltage applied to the piezo actuator during operation, can be "distributed" proportionally between a (hydraulically) effective stroke of the plunger on the one hand and the build-up of a sealing force of the plunger on the other, in particular by means of a corresponding control of the expansion element.

[0052] Advantageously, the plunger's adjustment position can be set by a combination of the expansion element and the (first) actuator so that the plunger exerts a specific sealing force on the nozzle in the adjustment position. The greater the plunger's sealing force in the adjustment position, the greater the proportion of the actuator deflection required for this sealing position relative to the maximum actuator deflection or piezoelectric actuator control voltage intended for operation. Consequently, the proportion of actuator deflection or piezoelectric actuator control voltage available for the (hydraulically) effective stroke of the plunger will decrease. Therefore, the (hydraulically) effective stroke of the plunger can be precisely adjusted by setting the plunger's adjustment position, and in particular by adjusting the sealing force.

[0053] This advantageously allows for further improved dosing accuracy.

[0054] To move the ejection element into the adjust position, the metering system, as mentioned, preferably comprises at least one heating device and / or at least one cooling device associated with the second actuator, in particular the expansion element. The metering system particularly preferably further comprises a control unit for controlling and / or regulating the heating device and / or the cooling device.

[0055] The heating device preferably uses electrical energy to heat the expansion material or the expansion element. For example, at least one resistance heating element in the form of a heating film could be arranged on an outer surface (outside) of the expansion element, e.g., on a housing of the expansion element. Alternatively or additionally, at least one resistance heating element could be arranged within the expansion material itself. Preferably, the heating device is designed to heat the entire expansion material of the expansion element uniformly to a specific target temperature.

[0056] The cooling device preferably comprises at least one gaseous and / or liquid fluid for cooling the expansion element or the expansion material. Preferably, the outer surface of the expansion element can be exposed to a cooling medium, at least in certain areas, for example, by directly exposing or blowing a cooling medium onto a housing of the expansion element. For this purpose, the cooling device can include a cavity (cooling area) in the metering system that surrounds the expansion element and can be flooded with cooling medium. Furthermore, the cooling device can include flow-directing elements to selectively apply cooling fluid to individual sections of the expansion element. However, it is also possible to actively cool substantially the entire outer surface of the expansion element. The cooling device can also include supply and discharge devices for introducing the cooling medium into the metering system, particularly into the cooling area, and for removing it from the metering system.

[0057] Preferably, the cooling medium is designed to cool the expansion element to a specific temperature as quickly as possible. This temperature can also be above room temperature and / or above the "parasitic" heating of the expansion element by the piezoelectric actuator. However, such a temperature is preferably below 45 °C, more preferably below 30 °C, and most preferably below 18 °C.

[0058] At least in cases where the temperature is above room temperature, air, especially compressed air, can also be used as a cooling medium. Uncooled compressed room air has the advantage of being relatively inexpensive and available in a sufficiently large volume flow.

[0059] Alternatively, cooled air, particularly cooled compressed air, can be used as the cooling medium. For example, the cooling medium can be actively cooled to a specific target temperature using a cooling source associated with the cooling unit, such as a chiller and / or a vortex tube. The cooling medium could then be designed to cool the expansion element to a temperature below the ambient temperature of the metering system.

[0060] The cooling capacity of the cooling device associated with the expansion element is preferably separately controllable and / or adjustable. Separate controllability is particularly advantageous if the dosing system's cooling device is also intended for temperature control of other components of the dosing system. For example, the cooling device could also be designed to temperature control the actuator, especially the piezoelectric actuator, in order to cool it to an operating temperature during operation. In this case, the cooling device associated with the expansion element can be designed as a separate sub-cooling device within a shared overall cooling device of the dosing system. Similarly, another sub-cooling device can be assigned to the actuator. Preferably, the overall cooling device can then comprise two separately controllable proportional valves to supply the expansion element and the actuator, respectively, with cooling fluid individually.

[0061] Preferably, the cooling and heating devices associated with the expansion element are designed to be separately controllable. This allows for a high degree of thermal decoupling of the expansion element from other components of the metering system. Particularly preferably, the cooling and heating devices can also be operated simultaneously. This allows a specific target temperature of the expansion element to be set very efficiently, while preventing temperature overshoot. Additionally, a slight, controlled interaction between the heating and cooling devices can contribute to increased temperature stability of the expansion element, e.g., against external disturbances.

[0062] For controlling and / or regulating the heating and / or cooling system, the dosing system preferably comprises at least one control unit. The dosing system can be coupled to an external control unit, such as a central control unit for separately controlling multiple dosing systems. Such a central control unit could be largely implemented in software, preferably in the form of a computer unit with suitable software. The computer unit can, for example, include one or more cooperating microprocessors or the like.

[0063] However, the dosing system can also have its own separate control unit. This can be implemented, for example, on a circuit board inside the housing. The control unit can be designed to independently control the entire dosing process. In this case, a central control unit would be unnecessary.

[0064] On the other hand, the "dosing system's own" control unit can also be designed to control only individual processes of the dispensing operation. Preferably, the "dosing system's own" control unit can then be designed as a sub-control unit of a central control unit and coupled to it via signal technology. For example, the "dosing system's own" control unit can be provided for controlling and / or regulating the second actuator, in particular the expansion element, i.e., especially for carrying out adjustment processes and for thermal and / or mechanical compensation functions. In contrast, the central control unit can control the remaining processes of the dispensing operation, e.g., the electrical circuitry of the piezo actuator. A "dosing system's own" control unit according to the second variant is described below without limitation. The control unit can also comprise several sub-control units, which can then jointly form the control unit.

[0065] The term "control" is used synonymously with "control" and / or "regulation" within the context of this application. This means that even when referring to "control," the control process can encompass at least one regulation process. In regulation, a controlled variable (actual value) is generally continuously measured and compared to a reference variable (setpoint). The regulation typically occurs in such a way that the controlled variable is adjusted to match the reference variable. This means that the controlled variable (actual value) continuously influences itself within the feedback loop.

[0066] In a preferred method for controlling the metering system, a number of operating parameters of the metering system can be taken into account when controlling and / or regulating the second actuator, preferably for controlling and / or regulating the expansion element, and more preferably for setting the temperature of the expansion element. In particular, at least one of the following operating parameters can be considered for setting, i.e., determining and / or reaching, the adjust position: A first operating parameter can be a temperature of the second actuator, in particular a temperature of the expansion element, and most preferably a temperature of the expansion material or of an expansion element within the expansion element. The expansion element and the expansion element will be explained in more detail later. A temperature of the (first) actuator and / or a temperature of the housing in one or more different housing areas can also be considered as an operating parameter.

[0067] To determine the temperature and other operating parameters, the dosing system can include a sensor array with a number of sensors coupled to the control unit. The measured values ​​from the respective sensors can be supplied to the control unit as (measurement) signals.

[0068] Preferably, the sensor arrangement comprises at least one temperature sensor associated with the second actuator, in particular the expansion element, preferably for determining the temperature of the expansion material. Preferably, the metering system may additionally comprise at least one temperature sensor associated with the first actuator and / or one temperature sensor associated with the housing.

[0069] Another operating parameter that can be included in the control of the expansion element is the position of the ejector element in the metering system. Preferably, the position of the ejector element can be determined via the position of a lever coupled to the ejector element (as part of the movement mechanism).

[0070] To detect this operating parameter, the sensor arrangement preferably includes at least one position sensor for determining the position of the ejector element. Such a position sensor can, for example, be implemented using a Hall sensor. Preferably, the movement of the plunger can also be calculated using the (measurement) signals from the Hall sensor. Alternatively or additionally, the sensor arrangement can include at least one motion sensor for determining the movement of the ejector element. A motion sensor can, for example, be implemented using an accelerometer. Preferably, the motion and / or position sensor can be used to determine the movement or position of the plunger relative to the position of the sensor.

[0071] Preferably, at least one thermally compensated Hall sensor can be arranged in a region of the housing such that the sensor can interact with a magnet in the area of ​​the plunger and / or in the area of ​​the lever to detect a stroke movement of the plunger (e.g., a vertical displacement measurement) during a respective ejection and / or retraction movement. Preferably, the Hall sensor can be arranged on an imaginary vertical axis with the plunger (corresponding to its longitudinal extent). Preferably, measurement data about the (hydraulically) effective stroke of the plunger can be obtained using the Hall sensor.

[0072] Another operating parameter can be the actuator's position, e.g., a specific deflection of the actuator. Preferably, the operating parameter can be an electrical control voltage applied to the piezo actuator.

[0073] Another operating parameter can be the quantity and / or weight of the metering agent to be dispensed from the nozzle of the metering system during each dispensing process. Such a measured value representing the quantity and / or weight of the dispensed metering agent can be determined, for example, by weighing. Alternatively or additionally, a "dosing volume-dependent" signal of the dispensed metering agent can be determined, for example, via an optical evaluation unit of the sensor arrangement. Preferably, a signal, such as a measured value, from a flow sensor for the metering agent can also be used as an operating parameter. The measured value can be determined, for example, by means of a volumetric flow meter in the area of ​​the nozzle opening.

[0074] The sealing force exerted by the ejector element when the dosing system is closed can also represent an additional operating parameter. The corresponding measured values ​​can be obtained using a force sensor in the plunger or nozzle, or alternatively, using a force sensor to determine the contact force of the first or second actuator.

[0075] Calibration data of the dosing system can be used as a further operating parameter, whereby the calibration data is preferably stored in the dosing system and can be read out by the respective control unit.

[0076] The calibration data can, in particular, normalize the Hall sensor and its signals and normalize a transfer function of an electrical control voltage of the piezo actuator in relation to a respective plunger position at an operating point, i.e., in an adjusted state of the lever system.

[0077] Furthermore, calibration data can relate to different heating zones of the dosing system. For example, a first heating zone can be assigned to a dosing fluid cartridge, a second heating zone to the fluidic unit, e.g., a feed channel, and a third heating zone to the nozzle in order to temper the dosing fluid in the respective heating zone, preferably differently.

[0078] Furthermore, calibration data can relate to a volume flow rate of a respective proportional valve in relation to a control voltage of the proportional valve at a given pressure.

[0079] Advantageously, the control of the expansion element can be implemented in such a way that at least the essential, preferably all, operating parameters of the metering system that can influence the plunger position and / or the (hydraulically) effective stroke of the plunger are taken into account. This allows the expansion element to be controlled precisely so that the adjustment position of the ejection element can be set with particular reliability during operation. By incorporating multiple operating parameters into the control system, a less fault-prone and more robust control can be achieved, further improving metering accuracy.

[0080] To determine and / or achieve the adjustment position of the plunger as precisely as possible, an adjustment process with a multi-step control algorithm can preferably be performed. Preferably, the individual steps of the control algorithm can be executed at least semi-automatically, and preferably fully automatically, by the control unit.

[0081] In a first step, the maximum deflection of the (first) actuator intended for operation of the dosing system can be set. This means that a "closed position" of the dosing valve can be set, whereby the ejection tip of the plunger is moved towards the nozzle. Preferably, regular dispensing of the metering material from the nozzle is not possible during the entire adjustment process, for example, by temporarily blocking a trigger that initiates the dosing process.

[0082] In a second step, an "adjustment start temperature" of the second actuator, in particular the expansion element, and especially preferably the expansion material itself, can be set. This ensures that the ejection tip of the plunger does not (yet) make contact with the nozzle at this point, despite the actuator already being expanded. Preferably, the expansion element can be cooled for this purpose. The adjustment start temperature can, for example, correspond to the ambient temperature of the metering system. Preferably, the adjustment start temperature can be below an expected (later defined) "adjustment temperature."

[0083] In a further step, the second actuator, in particular the expansion element, and especially preferably the expansion material itself, can be heated from the initial adjustment temperature until full contact is achieved between the ejection tip of the plunger and the nozzle. This means that the expansion element is expanded by the temperature to such an extent that the plunger is pushed towards the nozzle and finally makes contact with it. As mentioned, full contact is achieved when the ejection tip of the plunger rests substantially against the sealing surface of the nozzle, thereby sealing the nozzle opening in an annular manner.

[0084] To determine this point of full contact, a (calibration) relationship between the respective temperature of the expansion element and the corresponding position of the ejector element can preferably be determined during the heating of the expansion element. Preferably, this change in the position of the plunger in relation to the temperature change can be determined by the control unit. For this purpose, the control unit can, for example, access the temperature sensor of the expansion element and the position sensor of the lever coupled to the plunger and generate or store corresponding "temperature-position" value pairs. Preferably, corresponding "temperature-position" value pairs can be generated throughout the entire calibration process. As explained above, the position of the plunger can preferably be determined relative to the Hall sensor; for example, a distance to the Hall sensor can be determined.

[0085] Until full contact is reached, a predominantly linear (initial) (adjustment) relationship preferably develops between the temperature of the expansion element and the respective plunger position (the "ideal" metering system). This (adjustment) relationship corresponds, for example, to the slope of a function graph based on the aforementioned pairs of values. Once the "full contact point" is reached, the plunger tip is pressed further against the nozzle's sealing seat as the expansion element continues to heat up.

[0086] In an "ideal," very rigid metering system, further expansion of the expansion element essentially only leads to an increase in the sealing force of the plunger against the nozzle. Consequently, the plunger's position will no longer change, or at least not measurably, while the temperature of the expansion material continues to rise. A new (second), predominantly linear (adjustment) ratio is therefore established, which preferably differs from the first (adjustment) ratio. Preferably, the second (adjustment) ratio can correspond to a slope that differs from the slope of the first (adjustment) ratio. In the "ideal," very rigid metering system considered here, the slope of the second (adjustment) ratio would be approximately zero. The plunger position at which the transition from the first to the second (adjustment) ratio occurs corresponds to a full-contact position of the plunger.

[0087] In an "ideal" non-rigid metering system, the further expansion of the expansion element after full contact can lead to elastic deformation of components within the metering system. Accordingly, the position of the plunger may still change slightly after full contact. However, the change in the plunger's position relative to the temperature rise of the expansion element is preferably very small, in particular smaller than before full contact. Therefore, even in an "ideal" non-rigid metering system, a new (second) predominantly linear (adjustment) ratio is established. In such an "ideal" non-rigid metering system, the slope associated with the second (adjustment) ratio can be significantly smaller or shallower than the slope associated with the first (adjustment) ratio. Unlike in an "ideal" very rigid metering system, the second slope would, of course, not be approximately zero.The plunger position at which the transition from the first to the second (adjustment) ratio takes place corresponds to the full contact position of the plunger.

[0088] In a "non-ideal" or "real" metering system, the ejection tip of the plunger may initially only make contact with a conical sealing seat inside the nozzle on one side or only partially. This can occur, for example, if the plunger is not positioned exactly in the center of the nozzle or not aligned with the nozzle opening. Such contact, where only a portion of the plunger tip makes contact with the nozzle, is referred to as "initial contact" or "partial contact." Similarly, in a "real" metering system, the heating of the expansion element from the initial adjustment temperature can initially lead to partial contact, which is distinct from full contact.

[0089] Up to partial contact, a predominantly linear (first) (adjustment) relationship can be established between the temperature of the expansion element and the respective plunger position.

[0090] During the adjustment process, the expansion element can be heated further until the plunger finally "slides" into the nozzle due to the progressive expansion of the element, thus achieving the full contact between plunger and nozzle described above. This process of the plunger "sliding" into the nozzle is also referred to as the "shift process." Preferably, "temperature-position" value pairs can also be established, whereby the corresponding plunger position is assigned to the respective temperature of the expansion element.

[0091] Since the plunger is pressed into the full-contact position against a certain resistance from the nozzle after initial contact, its position changes more slowly relative to the temperature rise of the expansion element than before initial contact. A new (second) predominantly linear (adjustment) ratio is therefore established, which preferably differs from the first (adjustment) ratio. The plunger position at which the transition from the first to the second (adjustment) ratio occurs corresponds to the plunger's initial contact position. As an optional step, the initial contact position of the ejector element can be determined and, if necessary, stored. This value, together with the full-contact position, can provide information about the mechanical quality of the system and can therefore be helpful in system evaluation.Furthermore, the "initial contact temperature" of the expansion element, i.e., the temperature that the expansion element has at the time of initial contact, can also be determined and, if necessary, stored.

[0092] In a "real" dosing system, analogous to an "ideal" dosing system, full contact is defined by the (renewed) change in the (adjustment) ratio. Preferably, the expansion element can be heated further after the initial contact until a new (third) (adjustment) ratio is established. In a "real" dosing system, the plunger position at which the change from the second to the third (adjustment) ratio occurs corresponds to the plunger's full contact position.

[0093] Depending on the specific design of the "real" dosing system, the position of the plunger after reaching full contact can remain essentially constant during continuous heating of the expansion element (very rigid system) or change very slightly (non-rigid system), as previously explained for the respective "ideal" systems.

[0094] In a next step, the full-contact position of the ejector element can be determined and, if necessary, saved. Furthermore, the "full-contact temperature" of the expansion element, i.e., the temperature of the expansion element at the moment of full contact, can also be determined and, if necessary, saved.

[0095] In a further step of the adjustment process, an adjustment position of the ejector element can be determined and, if necessary, saved, preferably based on the previously determined "temperature-piston position" value pairs. Furthermore, an "adjust temperature" of the expansion element, i.e., the temperature of the expansion element at the desired adjustment point, can also be determined and, if necessary, saved. As mentioned, the adjustment position is an empirically determined value at which, for example, just enough sealing force is generated between the piston and the nozzle to guarantee a reliable seal of the system during operation.

[0096] The determination of the adjust position and / or the adjust temperature can preferably be carried out at least as a function of the full contact position of the ejection element and / or as a function of the full contact temperature of the expansion element.

[0097] Preferably, the adjust position of the ejection element can be determined at least as a function of a full contact position of the plunger and a slope of an (adjustment) ratio, wherein the (adjustment) ratio results from a change in position of the plunger in relation to a temperature change of the expansion element, in particular until initial contact is reached or until full contact is reached.

[0098] The adjustment position of the ejection element can be calculated particularly conveniently using the following equation: s AP = s VP + m ⋅ T DS FS m

[0099] These include: s(AP) = Position of the ejector element in the adjust position. For this, a corresponding adjust temperature of the expansion element is determined, preferably based on the previously recorded "temperature-position" value pairs. s(VP) = Position of the ejector element at full contact, and from this, a corresponding full-contact temperature of the expansion unit is determined. m = (Δs / ΔT) = Slope of a function graph based on "piston position-temperature" value pairs until initial contact is reached ("real" system) or until full contact is reached ("ideal system") (depending on which contact is reached first). T = Required temperature difference of the expansion element, starting from full contact, to achieve a desired sealing force of the piston. Preferably, a temperature difference value T can be determined as a function of a total spring stiffness FS of an actuator system, as a function of a desired sealing force DS, which, for example,The spring stiffness (FS) can be stored in the firmware of the dosing system and calculated based on the determined slope m. The overall spring stiffness (FS) is understood as a kind of average spring stiffness of a dosing system, where the spring stiffness can be measured on several units of the dosing system and, if necessary, averaged over several units.

[0100] Additionally, the adjustment position can depend on an application-specific parameter, which is included in the determination process. For example, it can be advantageous to compensate for the forces acting on the plunger at a particularly high supply pressure of the medium to be metered by an initially higher sealing force, thus including the supply pressure as an application-specific parameter.

[0101] In a very rigid metering system, the position of the plunger should essentially remain unchanged after full contact. Therefore, s(AP) is essentially equal to s(VP), where the difference due to the term m·T does not result in a further change in position, but only in the necessary build-up of sealing force by the plunger.

[0102] Preferably, the position of the plunger in the Adjust position can therefore be essentially the same as the position of the plunger in the full contact position and / or essentially the same as the position of the plunger in an ejection end position, which will be explained in more detail later.

[0103] In a non-rigid metering system, the specific overall spring stiffness FS can be taken into account when determining s(AP) by the term m·T, so that elastic deformation is compensated and a desired sealing force can be built up in the adjust position. Preferably, even in a non-rigid metering system, the position of the plunger in the adjust position can be essentially the same as the position of the plunger in the ejection end position. Preferably, the position of the plunger in the adjust position can approximate the position of the plunger in the full-contact position.

[0104] In summary, the adjustment position of the plunger for setting a desired sealing force can preferably be determined by considering at least a (previously determined) full-contact position of the plunger, an (initial) slope (via temperature) of the still freely movable plunger, and a total spring stiffness of the metering system stored in the system. Alternatively, a desired sealing force (adjustment force) and thus also an adjustment temperature could be directly set using a force sensor (to be explained later).

[0105] Preferably, the adjustment position s(AP) of the ejector element can be set via the expansion element. Particularly preferably, an adjustment temperature can be set in the expansion element to bring the ejector element into the adjustment position. Therefore, in a final optional step of the adjustment process, the ejector element can preferably be brought into the adjustment position by appropriately heating the expansion element to the temperature determined for the adjustment point. For this purpose, the expansion element can preferably be heated further beyond the full-contact temperature until the adjustment position of the ejector element is reached.

[0106] The achievement or setting of the respective adjust position depends on the specific design of the dosing system, as explained below.

[0107] In an "ideal," very rigid metering system, full contact can already correspond to the plunger's adjustment position. As explained previously, heating the expansion element beyond the full contact temperature primarily results in the plunger building up a sealing force. However, the plunger's position remains essentially constant. Therefore, the plunger's full contact position can preferably correspond to its adjustment position.

[0108] In an "ideal" non-rigid, i.e., at least partially elastic, metering system, the position of the plunger can, as mentioned, still change slightly after full contact due to elastic deformation of components within the metering system. Therefore, a (second) predominantly linear (adjustment) relationship can be established after full contact, which preferably has a very slight slope. The adjustment position is reached when the desired sealing force is achieved.

[0109] In a "real" metering system, the transition from a second to a third (adjustment) ratio defines the full-contact position of the plunger. Accordingly, in a very rigid "real" metering system, the plunger position at which the transition from the second to the third (adjustment) ratio occurs can correspond to the plunger's adjustment position. Preferably, the slope associated with the third (adjustment) ratio can then be approximately zero.

[0110] In contrast, with a non-rigid "real" dosing system, the plunger can still be moved slightly into the adjust position according to a third (adjustment) ratio or according to an associated third slope, whereby no further change in position occurs after reaching the adjust position, since the expansion element is no longer expanded.

[0111] As already explained, in a non-rigid metering system the plunger can still be moved slightly after full contact, although here too, a large part of the further expansion of the expansion element after full contact can be used to adjust a sealing force of the plunger.

[0112] Alternatively or additionally, the adjustment process can also include heating the second actuator, in particular the expansion element, beyond the full-contact temperature until a maximum operating "system deflection" is reached. The maximum "system deflection" corresponds to the maximum intended operating deflection of the (first) actuator and the maximum intended operating expansion of the expansion element.

[0113] Accordingly, the adjustment process can then determine and optionally store the "system end contact" position of the ejector element; that is, the position the ejector element has at maximum system deflection during operation. Furthermore, the "system end contact" temperature of the expansion element can be determined and optionally stored; that is, the temperature the expansion element reaches at the maximum system deflection intended for operation. Preferably, the "system end contact" position and / or the "system end contact" temperature can also be determined based on "temperature-piston position" value pairs.

[0114] The "system end contact" position of the ejection element and / or the "system end contact" temperature of the expansion element, as determined in this way, can be taken into account alternatively or additionally to the full contact position or the full contact temperature when determining the adjust position and / or the adjust temperature.

[0115] In order to move the ejection element from the "system end contact" position to the specific adjust position, the expansion element can optionally also be brought to the adjust temperature assigned to the adjust position by means of cooling.

[0116] Furthermore, the "system end contact" position defined in this way also represents a measure of the maximum control range during operation. The highest possible sealing force can be achieved in the "system end contact" position. Advantageously, the difference between a specific adjustment position and the "system end contact" position provides information about a control reserve and thus, potentially, about the existing wear of the dosing system.

[0117] The previously described adjustment process can be performed before the initial commissioning of the dosing system, for example, to determine an initial adjustment position. However, the adjustment process can also be performed (again) after a temporary interruption of dosing operation, for example, after replacing a plunger. Routine adjustment of the dosing system is also possible.

[0118] Advantageously, the expansion element allows for a particularly precise and straightforward adjustment of the plunger's position during the adjustment process. This process is also known as "thermal adjustment" via the expansion element. Since the adjustment position can be determined separately for each dosing system, any manufacturing tolerances of each individual dosing system can be compensated for by the control unit itself. This allows for the setting of a substantially identical (hydraulically) effective stroke in dosing applications with a large number of dosing systems, meaning the dosing systems can dispense with exceptional comparability.

[0119] Another advantage is that the adjustment process is relatively straightforward. The dosing system can, for example, be designed so that the adjustment process is initiated by a user inputting a command to the control unit, with the entire adjustment then running automatically. This reduces the operating costs of the dosing system, as the adjustment can now be performed by the user themselves, even by untrained personnel. At the same time, the adjustment process is highly reliable, as human intervention—and the associated potential for error—can be largely avoided. This further improves the dosing accuracy of each system and, above all, the comparability of dosing across multiple systems.

[0120] To profitably utilize the previously explained advantages of the adjustment process during dosing, the second actuator, in particular the expansion element, is preferably controlled and / or regulated such that the ejection end position of the ejection element during operation of the dosing system, especially during each ejection cycle, corresponds precisely to an adjustment position determined in a previously performed adjustment process. Preferably, the control and / or regulation of the expansion element can be determined based on the actual ejection end position of the plunger during a given ejection cycle and taking into account any changes in the piezoelectric actuator control voltage during the same ejection cycle. The "ejection end position" is understood to be the position of the plunger that it actually occupies at the end of a given ejection cycle, i.e., at the maximum deflection of the (first) actuator intended for operation.Preferably, the position of the plunger in the ejection end position can be essentially the same as the position of the plunger in the adjust position.

[0121] Preferably, a control process can be implemented such that the ejection end position is regulated to a constant value during operation, in particular to the Adjust position. For this purpose, the expansion element can be controlled so that an Adjust temperature, which, as mentioned, corresponds to the previously determined Adjust position, is reached and / or maintained constant during operation. Preferably, a PID controller or fuzzy controller coupled to the control unit can control the heating and / or cooling device of the expansion element to set the Adjust temperature.

[0122] Advantageously, the control process can also ensure that a desired (hydraulically) effective stroke of the plunger is reliably achieved during operation and can be maintained constantly over a longer period of time.

[0123] However, setting or maintaining a constant temperature in the expansion element can also be useful when there is a temporary cessation of dosing, for example, when the dosing system is temporarily in standby mode (hold mode). Preferably, the PID controller can also be used to keep the temperature in the expansion element constant when the dosing system is at a standstill. This ensures that high dosing accuracy is maintained immediately upon resumption of the dosing process.

[0124] To ensure particularly stable operation of the dosing system, the system can include at least one force sensor, which is preferably coupled to the control unit via a signal connection. Preferably, measured values ​​from the force sensor can be taken into account when controlling the expansion element.

[0125] The force sensor is preferably configured to determine the force exerted by the second actuator, in particular the expansion element, on the (first) (piezo) actuator. In particular, the force sensor can also be configured to determine, for example with the aid of an evaluation unit (which can also be part of the control unit), a sealing force of the plunger against the nozzle based on the measured values ​​of the force sensor. Preferably, the force sensor can be arranged in a "force line" with the expansion element and the piezo actuator. For example, the force sensor can be arranged at a support point or contact point of the expansion element opposite the piezo actuator.

[0126] Advantageously, the force sensor allows for direct control to maintain a constant force. In particular, the force sensor can be used to constantly regulate the sealing force of the plunger. Since the spring stiffness of the overall system should not change during operation, seamless control is possible in all operating modes, including hold mode.

[0127] To further improve dosing accuracy, particularly under fluctuating operating or environmental conditions, a preferred control method for the dosing system can employ a multi-step control algorithm to precisely adjust the ejection end position of the plunger to the desired adjustment position, determined previously (e.g., as described above), or indirectly to a specific sealing force. Preferably, the individual steps of the control algorithm can be executed by the control unit, particularly fully automatically. This correction algorithm can preferably be run during ongoing (regular) dosing operation.

[0128] The control algorithm can generally be executed during a closing edge and / or an opening edge, i.e., during the dispensing of the metering material or during the retraction of the plunger. Depending on the metering requirements, the opening edges can be processed at slightly slower speeds than the closing edges, allowing more data pairs to be acquired at a given sampling rate during a single opening edge, resulting in more precise evaluation. Therefore, using the opening edge may even be preferable. However, unless otherwise stated, the individual steps of the control process are described below using a closing edge as an example, without limitation.

[0129] As a first step, an initial ejection position of the ejector element can be set. This initial ejection position is characterized by the (first) actuator not being deflected, i.e., the (first) actuator being in a rest position. Accordingly, the ejection tip of the plunger is positioned as far from the nozzle as is possible during operation. The control algorithm therefore preferably starts as soon as a plunger retraction movement is completely finished or immediately before a new ejection movement begins. The initial ejection position can be determined, for example, via the Hall sensor and / or the electrical control voltage of the (first) actuator, particularly the piezoelectric actuator.

[0130] In a second step, during a single ejection cycle, the deflection of the (first) actuator and / or the change in the electrical control voltage of the (first) actuator can be detected as a function of time. Preferably, this allows the deflection rate of the (first) actuator to be determined, starting from the actuator's rest position up to its maximum deflection (as provided for in operation). Preferably, the change in the electrical control voltage applied to the (first) actuator, in particular to the piezo actuator, over time can be detected (rate of change of the control voltage).

[0131] Preferably, the plunger position can also be recorded as a function of time during the same ejection process. Preferably, the plunger velocity can then be determined from this, starting at the initial ejection position and continuing until the plunger reaches its final ejection position. As mentioned, the plunger position can be recorded using the Hall sensor.

[0132] Preferably, the rate of change of the control voltage of the piezo actuator and the corresponding plunger velocity are repeatedly determined at essentially the same times. Therefore, preferably, pairs of values ​​("control voltage-plunger position" value pairs) can be regularly recorded by the control unit over the duration of the ejection process, wherein the value pairs comprise the respective actuator control voltage (first actuator) and the corresponding (associated) plunger position.

[0133] In a further step of the control algorithm, an actual value representing a sealing actuator deflection can be determined. As mentioned, the sealing actuator deflection can be a portion of the maximum deflection of the first actuator intended for operation. Preferably, the sealing actuator deflection can be a portion of the maximum electrical control voltage applied to the piezo actuator (as the first actuator) during operation. The sealing actuator deflection is defined by the fact that the ejector element is pressed into the nozzle's sealing seat by a certain minimum amount beyond full contact between the ejector element and the nozzle. The sealing actuator deflection is therefore specifically that portion of the actuator deflection that brings the plunger into the sealing area and thus generates the desired sealing force.

[0134] A value representing the sealing position actuator deflection can preferably be a component (a partial voltage) of the maximum electrical control voltage applied to the piezo actuator (as the first actuator) during operation, in order to set a specific sealing force of the plunger. In a pneumatic actuator, for example, a gradual pressure build-up in relation to the corresponding plunger position could be detected. The sealing position actuator deflection could then correspond to a specific pressure increase that is still required, starting from full contact, to build up the sealing force.

[0135] This means that by determining the sealing position actuator deflection, in particular its extent, it can be determined whether the plunger is moved into a desired adjustment position, or whether the ejection movement ends at a different ejection end position, e.g. at an "earlier" or "later" point.

[0136] Determining the value representing the sealing actuator deflection can preferably be based on previously determined "control voltage-plunger position" value pairs. Preferably, the rate of change of the control voltage of the piezo actuator (as the first actuator) can be compared with the corresponding plunger velocity, particularly over the entire ejection process. Preferably, a ratio between the rate of change of the control voltage and the plunger velocity can be determined.

[0137] The rate of change of the electrical control voltage of the piezo actuator can remain essentially constant throughout the entire ejection process. However, more complex control voltage functions are also possible, meaning the control voltage can vary during the ejection process. In the case of a constant rate of change of the electrical control voltage of the piezo actuator, the displacement speed of the piezo actuator can vary during different phases of the ejection process. Due to the coupling between the (piezo) actuator and the ejector element, e.g., via a lever, the two components form a "movement unit." Accordingly, the plunger velocity can also vary during a given ejection process, as explained below.

[0138] At the beginning of each ejection process, the plunger can initially be moved towards the nozzle at a predominantly constant speed by the deflection of the (piezo) actuator. Therefore, an initial speed ratio can be established between the rate of change of the piezo actuator control voltage and the plunger speed.

[0139] In an "ideal," very rigid metering system, the plunger speed can slow considerably after full contact, especially approaching zero, while the plunger is pressed further into the nozzle. For a piezoelectric actuator, this means that the electrical control voltage increases essentially constantly, but the plunger no longer moves measurably. Due to the coupling between the piezoelectric actuator and the plunger, the longitudinal expansion of the piezoelectric actuator also remains almost unchanged. This means that the increase in electrical control voltage leads to a predominantly constant pressure increase, or a (mechanical) stress build-up in the piezoelectric actuator, which then generates the sealing force of the plunger.

[0140] Therefore, after full contact, a second (speed) ratio between the rate of change of the control voltage and the plunger speed can be established, which preferably differs from the first ratio. The plunger reaches its full-contact position at the moment, or at the plunger position, where the change from the first to the second (speed) ratio occurs. As already explained, in an "ideal" very rigid metering system, the full-contact position of the plunger can preferably be essentially the same as the plunger's ejection end position, with the maximum control voltage intended for operation applied to the piezoelectric actuator.

[0141] In an "ideal" non-rigid dispensing system, the plunger speed can also slow down significantly after full contact, resulting in a second (speed) ratio. The plunger position at which the transition from the first to the second (speed) ratio occurs corresponds to the plunger's full-contact position. This second (speed) ratio represents a slight change in plunger position due to elastic deformation of dispensing system components. The plunger can continue to move slightly until the maximum control voltage intended for operation is applied to the piezoelectric actuator, at which point the plunger reaches its final ejection position.This means that in the case of a non-rigid system, unlike a rigid system, after full contact a small part of the electrical voltage change of the piezo actuator can still be converted into a change in the position of the plunger, while the majority flows into the force change.

[0142] In a "real" dosing system, a first (speed) ratio can be established before initial contact, after which the plunger speed may slow down due to the "shift process." The plunger position at which a change from the first to a second (speed) ratio occurs then corresponds to the plunger's initial contact position. Once the plunger has "slid" into the full contact position due to actuator deflection, the plunger speed can slow down significantly, establishing a third (speed) ratio. The plunger position at which a change from the second to the third (speed) ratio occurs then corresponds to the plunger's full contact position.

[0143] Depending on the design of the metering system, the full contact position may correspond to the ejection end position (rigid system). Otherwise, the plunger can be moved according to the third (speed) ratio until it reaches the ejection end position defined above.

[0144] Ideally, the ejection end position should correspond to the intended adjustment position. As mentioned, the adjustment position can preferably be set taking into account the desired sealing force and the spring stiffness of the metering system. However, during operation of the metering system, it can happen that the actual ejection end position of the plunger deviates from a previously determined adjustment position. This can be caused, for example, by a thermally induced change in the length of the piezo actuator and / or wear of moving components and / or a change in the temperature of a housing of the metering system and / or a change in the ambient temperature of the metering system. Accordingly, the actual sealing position actuator deflection (as the actual value) can also deviate from a "target value" of the sealing position actuator deflection (to reach the adjustment position).

[0145] To determine the actual value representing the sealing position actuator deflection, the actual proportion of the actuator deflection (of the first actuator) that pushes the plunger into the nozzle from the full contact position to the ejection end position can be determined. The actual value representing the sealing position actuator deflection can be derived from the difference between the maximum actuator deflection during operation and the actuator deflection required to reach full contact. Preferably, the actual value of the current sealing position actuator deflection can be a voltage difference between the maximum electrical control voltage applied to the piezoelectric actuator (as the first actuator) during operation and the electrical control voltage required to move the plunger to the full contact position.

[0146] To control the ejection end position during operation to a specific adjustment position, a further step of the control algorithm can determine the difference between the actual value representing the sealing actuator deflection and a target value representing the sealing actuator deflection. Preferably, the expansion element can be controlled based on the determined difference so that the target value representing the sealing actuator deflection is reached during operation.

[0147] This setpoint, representing the actuator deflection for the sealing position, is preferably assigned to a specific adjust position. This means that the plunger can be moved to the desired adjust position by a control system based on this setpoint ("target sealing actuator deflection"). The setpoint can preferably be a voltage difference between the control voltage required to reach the full contact position and the maximum electrical control voltage applied to the (first) actuator during operation. The setpoint for the sealing actuator deflection can be factory preset and is preferably stored in the control unit, e.g., in an EEPROM. Alternatively or additionally, the setpoint for the sealing actuator deflection can also be stored in a separate memory, preferably an EEPROM, of the dispensing system, ready for retrieval. The setpoint can, for example, be a percentage of the maximum possible stroke of the (first) actuator during operation.This could be a change in length of a calibrated (first) actuator. Alternatively, the setpoint could also be achieved using a force value.

[0148] Preferably, the setpoint of the value representing the sealing actuator deflection can be adjusted via the temperature of the expansion element. Particularly preferably, the temperature of the expansion element can be constantly regulated to a specific voltage difference of the piezo actuator control voltage (as the setpoint).

[0149] Preferably, the second actuator, in particular the expansion element, can be controlled such that, in the event of a negative deviation of the actual value from the target value representing the sealing position actuator deflection, the temperature of the second actuator, in particular the expansion element, is increased to adjust the target value of the sealing position actuator deflection. Conversely, in the event of a positive deviation of the actual value from the target value representing the sealing position actuator deflection, the temperature of the second actuator, in particular the expansion element, can be reduced to adjust the target value of the sealing position actuator deflection.

[0150] The required temperature of the expansion element can preferably be determined using the previously introduced equation (1).

[0151] As previously explained, the control process can also be executed during each "opening" edge. Accordingly, to control the ejection end position, an ejection end position of the ejector element can be set in a first step. In a next step, the position of the ejector element can be determined as a function of the deflection of the first actuator during a retraction movement of the ejector element. Particularly preferably, the position of the ejector element can be determined as a function of an electrical control voltage applied to the first actuator or to the piezoelectric actuator. Preferably, "control voltage-plunger position" value pairs can again be acquired for this purpose, as previously described.

[0152] In a further step, an actual value representing the sealing actuator deflection can be determined. The actual and target values ​​representing the sealing actuator deflection (of the first actuator) are defined as previously explained for the "closing" edge.

[0153] In a subsequent step, the second actuator, preferably the expansion element, can be controlled and / or regulated, particularly depending on a difference between the actual value representing the sealing position actuator deflection and a setpoint value representing the sealing position actuator deflection, such that a setpoint value representing the sealing position actuator deflection is set. The control and / or regulation of the second actuator is preferably carried out as previously described for a "closing" edge.

[0154] Preferably, the described control process (controlling the target sealing actuator deflection) can be executed at regular intervals during operation of the dosing system, e.g., during each ejection cycle of the plunger. However, it is preferred to first "filter" the actual values ​​of the sealing actuator deflection recorded during each ejection cycle, e.g., to compensate for any measurement inaccuracies. Preferably, a mean value and / or a median value can be calculated from a number of individual measurements, e.g., 10 individual measurements, whereby this median or mean value can then be fed back into the control process as the current reference variable (target value of the sealing actuator deflection).

[0155] Preferably, during a first ejection process, a difference between the actual value and the target value of the value representing the sealing position actuator deflection can be determined, whereby a "new" adjust temperature is determined depending on the difference in order to set the adjust position under the current operating conditions.

[0156] Preferably, the "new" adjust temperature determined during the (first) ejection process can be used to control the expansion element during a subsequent (second) ejection process. This means that the adjust temperature can be continuously recalculated during operation.

[0157] The adjust temperature can preferably be continuously re-determined as a function of a number of immediately previously determined actual values ​​of the sealing position actuator deflection, especially after a "filtering" of the individual values.

[0158] Advantageously, determining the current sealing actuator deflection allows for particularly dynamic control of the expansion element. Specifically, the expansion element can be controlled so that the dispensing element is moved into the adjust position with each dispensing movement. This advantageously compensates for various disturbances, such as thermal expansion effects of the piezo actuator, wear of the plunger and / or nozzle, etc. In particular, the expansion element can be controlled to prevent leaks during metering. Furthermore, the continuous adjustment of the target sealing actuator deflection or the adjust temperature allows for further improvement of metering accuracy, even during continuous operation, especially with varying metering requirements and / or under highly fluctuating environmental conditions.

[0159] In order to adjust the position of the plunger particularly efficiently, the second actuator, in particular the expansion element, as mentioned, comprises an expansion body and preferably a slidably mounted transmitter coupled to it, e.g. a movable piston.

[0160] The expansion element, which forms the expansion material of the expansion element, is preferably a solid. In particular, the expansion element can exist as a solid at the adjustment temperatures typically occurring during operation of the metering system. For example, the expansion element can exist as a solid at temperatures up to 250°C, preferably up to 260°C, and more preferably up to 350°C. Preferably, the expansion element has a thermally induced high coefficient of expansion, in particular a higher coefficient of expansion than a metal or ceramic housing of the expansion element. For example, the coefficient of expansion of the expansion element can be at least 23 × 10⁻⁶ K / K, preferably at least 45 × 10⁻⁶ K / K, and more preferably at least 100 × 10⁻⁶ K / K. A suitable material for the expansion element can be a polymer, e.g., PEEK, PFA, or polytetrafluoroethylene.

[0161] The expansion element can preferably be arranged in a housing or chamber of the expansion material, e.g., in a stainless steel housing. Preferably, the housing can be designed as a hermetically sealed chamber. This offers the advantage that the expansion material can be introduced into the chamber in liquid form and can solidify there, particularly without bubbles.

[0162] The second actuator, in particular the expansion element, can preferably be coupled to the (first) actuator in an axial direction, e.g., corresponding to the longitudinal extent of the piezo actuator, in order to position the (first) actuator in the housing. Preferably, the expansion element can be mechanically connected in series with the piezo actuator in the housing of the dispensing system. Preferably, the expansion element can be supported on the housing of the dispensing system with at least one side, preferably a side facing away from the (first) actuator.

[0163] Preferably, the expansion element is designed and arranged in the housing such that only the pressure side of the expansion element, pointing towards the actuator, is displaceable. Preferably, the pressure side can be displaced along a longitudinal axis of the actuator, particularly the piezoelectric actuator. This ensures that, when the volume of the expansion element changes, the dimensions of the expansion element change essentially only along the longitudinal axis of the actuator, while the lateral dimensions of the expansion element remain largely constant ("forced expansion direction"). The volume change of the expansion material can thus be converted into a directed stroke movement to displace the actuator, particularly the piezoelectric actuator, preferably along its longitudinal extent.

[0164] For positioning the actuator, the expansion element, particularly its pressure side, can be coupled to the actuator by means of a transmitter. Preferably, a stroke movement of the expansion element can be transmitted almost entirely to the actuator via the transmitter to move it within the housing. As mentioned above, the coupling between the expansion element (transmitter) and the (first) actuator need not be a rigid connection. Preferably, the coupling can be such that an operating unit consisting of the expansion element and the actuator is held under constant preload during operation, particularly even when the (first) actuator is not deflected. For example, a side of the expansion element facing away from the actuator could be adjustably mounted relative to the housing of the metering system by means of an adjustable spherical cap.

[0165] The invention is explained in more detail below with reference to the accompanying figures and exemplary embodiments. The same components are designated with identical reference numerals in the various figures. The figures are generally not to scale. They schematically show: Figure 1 a cross-sectional view of a dosing system according to an embodiment of the invention, Figures 2 and 3 Parts of the dosing system made of Figure 1 in an enlarged view, Figures 4 to 6 Parts of the dosing system made of Figure 1 in a further enlarged and greatly simplified view, Figures 7a to 7c Flowcharts of sections of a method for controlling the dosing system according to an embodiment of the invention, Figures 8 to 12 Representations of function graphs to illustrate subsections of the procedure according to the Figures 7a to 7c for controlling the dosing system.

[0166] Based on Figure 1A specific embodiment of a dosing system 1 according to the invention will now be described. The dosing system 1 is shown here in its usual intended position, e.g., during operation. A nozzle 60 is located in the lower region of the dosing system 1, so that the droplets of the medium are ejected downwards through the nozzle 60 in an ejection direction R. Therefore, wherever the terms "bottom" and "top" are used below, these descriptions always refer to such a generally common position of the dosing system 1. However, this does not preclude the possibility that the dosing system 1 can also be used in a different position in specific applications, with the droplets, for example, being ejected laterally. Depending on the medium, pressure, and the precise design and control of the entire ejection system, this is also fundamentally possible.Since the basic structure of dosing systems is known, for the sake of clarity, predominantly those components are shown here that at least indirectly relate to the invention.

[0167] The dosing system 1 comprises as essential components an actuator unit 10 and a fluidic unit 50 coupled to it. The dosing system 1 shown here also includes a dosing agent cartridge 66, which is coupled to the fluidic unit 50.

[0168] In the embodiment shown here, the actuator unit 10 and the fluid unit 50 are implemented as interlocking plug-in couplings to form a quick-release coupling. Advantageously, the actuator unit 10 and the fluid unit 50 can thus be coupled without tools to form the metering system 1. The quick-release coupling comprises a coupling mechanism 70 with a coupling spring 71, which holds a ball 72 under constant preload. The coupling spring 71 and the ball 72 are enclosed by a (first) housing block 11a and form a first plug-in coupling component. The first plug-in coupling component further comprises a heating device 75 for heating the metering material in the nozzle 60.

[0169] The coupling mechanism 70 has a number of spherical caps 74 (only one is shown here) into which the ball 72 can engage for coupling. The spherical caps 74 are arranged in a second plug-in coupling part 73 of the fluidic unit 50, the fluidic unit 50 being enclosed by a (second) housing block 11b. For coupling, the first plug-in coupling part and the second plug-in coupling part can be inserted into one another along a (virtual or imaginary) plug-in axis and thereby coupled to each other. For example, the fluidic unit 50 can be inserted into the actuator unit 10 in the opposite direction R and coupled to the actuator unit 10 in a suitable rotational position.

[0170] The ball caps 74 are arranged in the second plug-in coupling part 73 of the fluidic unit 50 such that various locking positions are possible, i.e., different rotational positions of the fluidic unit 50 around the plug-in axis are possible. The spring-loaded ball 72 engages the plug-in coupling part 73 in one of the several possible locking positions, thus forming the metering system 1. It should be noted, however, that the respective assemblies 10 and 50 can also be rigidly connected to one another, e.g., by means of a fixing screw, to form the housing 11 with the two housing blocks 11a and 11b.

[0171] In the embodiment shown here, the actuator unit 10 comprises two internal chambers: firstly, an actuator chamber 12 containing a piezoelectric actuator 20, and secondly, an action chamber 13 into which a movable ejection element 51, here a plunger 51, of the fluidic unit 50 projects. Via a movement mechanism 14 with a lever 16, which projects from the actuator chamber 12 into the action chamber 13, the plunger 51 is actuated by the piezoelectric actuator 20 such that the fluidic unit 50 ejects the medium to be metered in the desired quantity at the desired time.

[0172] To control the piezo actuator 20, it is electrically and / or via a signal connection to an external control unit (not shown). The piezo actuator 20 comprises an actuator housing 22 and a piezo stack 21 hermetically encapsulated within it, isolated from the environment. The piezo actuator 20 can expand and contract longitudinally within the actuator chamber 12 according to a circuit signal from the control unit. Since the basic function and control of piezo actuators are well-known, they will not be discussed further here.

[0173] At the upper end (pointing away from the nozzle 60) of the piezo actuator 20, the piezo actuator 20 (as the first actuator 20) is in indirect operative contact with a thermal expansion element 30 (as the second actuator 30). The thermal expansion element 30 comprises a housing 31, which encloses a cylindrical expansion body 32 on five sides (three sides in cross-section). The housing 31 is designed such that any thermal expansion movement of the expansion body 32 is directed predominantly towards the piezo actuator 20.

[0174] On the side where the expansion element 32 is not bounded by the chamber 31, the expansion element 32 abuts a transmitter 35. The transmitter 35 is movably mounted in the housing 31 of the expansion element 30 and can be moved along the longitudinal axis of the piezo actuator 20. On its lower side, the transmitter piston 35 abuts the piezo actuator 20 or rests directly on an outer surface of the actuator housing 22. This means that the expansion element 32, the transmitter 35, and the piezo actuator 20 are in operative contact with each other in such a way that a stroke of the expansion element 32 can be used almost entirely for positioning the piezo actuator 20. The piezo actuator 20 can therefore be moved "upwards" or "downwards" by means of the expansion element 30, which essentially corresponds to an ejection direction R of the metering material from the nozzle.

[0175] The nominal stroke of such an arrangement, i.e., the extent of a possible displacement of the piezo actuator 20, depends in particular on the diameter of the expansion element 30 and the volume of expansion material enclosed therein, as well as on the usable temperature range and the respective coefficients of thermal expansion of the surrounding housing 31, which can be made of, for example, metal or ceramic, and of the expansion element 30. For thermal compensation measures, a design for a nominal stroke in the range of the nominal stroke of the piezo actuator or less is advantageous, which can correspond to a few micrometers down to a few hundredths of a millimeter. For the combination of thermal adjustment and thermal compensation described here, a nominal stroke of the expansion element 30 of at least 10 µm, preferably at least 50 µm, and particularly preferably at least 100 µm is provided.

[0176] To control the expansion length of the expansion body 32, the expansion element 30 includes a heating device 33. This is particularly advantageous in Figure 2 clearly. The heating device 33 is a heating film 33 which rests on an outer surface of the housing 31 of the expansion element 30. A temperature sensor 83 for determining the temperature of the expansion element 30 is also arranged on the outer surface of the housing 31. For control, the expansion element 30, in particular the heating device 33, is connected by means of connecting cables 81 to a control unit 80 integrated into the dosing system ( Figure 1 ) tied together.

[0177] The "dosing system's own" control unit 80 is located here ( Figure 1The sub-control unit 80 is implemented as a partial control unit of a central external control unit (not shown) and is coupled to it via connecting cables 81. The sub-control unit 80 can, for example, be implemented using a circuit board 80 in the housing 11 of the dosing system 1. The "dosing system-integrated" control unit 80 is designed to control the expansion element 30 during operation, in particular to supply the heating device 33 and a cooling device 40 with corresponding control signals in order to set a desired expansion of the expansion body 32.

[0178] The dosing system 1 from Figure 1The cooling device 40 further comprises a cooling unit, which is designed to cool the expansion element 30 and the piezo actuator 20 separately. The cooling unit 40 includes several components that are used jointly for cooling the expansion element 30 and the piezo actuator 20. These include, among others, a coupling point 41, e.g., a connection for an external cooling medium supply, a subsequent inlet channel 42 for cooling medium, and a cooling medium outlet 46.

[0179] However, the cooling device 40 comprises two separate proportional valves 43, 44, which can be controlled separately by the control unit 80. The proportional valve 43 associated with the expansion element 30 is connected to a cooling zone 34 via a separate bore 42'. The cooling zone 34 surrounds the expansion element 30 in an annular form and is intended solely for cooling the expansion element 30. The cooling zone 34 can be flooded with a cooling medium, e.g., compressed and / or cooled air, via the proportional valve 43 and the bore 42' in order to cool the expansion element 30 as required.

[0180] The cooling of the piezo actuator 20 can be controlled separately by means of the second proportional valve 44, whereby cooling medium can be supplied to the actuator chamber 12 via an inlet channel 42". The cooling of the expansion element 30 and the piezo actuator 20 is thus largely thermally decoupled. The cooling medium can be discharged from the cooling area 34 and from the actuator chamber 12 via separate outlet channels (not shown here) and then flow out of the metering system 1 via a shared outlet channel 45 and a coupling point 46 for cooling medium discharge.

[0181] In order to position the piezo actuator 20 as desired during operation using the expansion element 30, an operating unit consisting of the expansion element 30 and the piezo actuator 20 is held under constant preload for coupling. For this purpose, the expansion element 30 includes a centering element 36, which is supported on top of the expansion element 30 ( Figure 1The centering element 36 is supported against the housing 11 of the metering system 1 and is designed to exert a specific pressure on the expansion element 30 and thus also on the piezo actuator 20. The piezo actuator 20 is supported at its lower end by a pressure piece 23 on a lever 16 of the movement mechanism 14.

[0182] The lever 16 of the movement mechanism 14, which serves to transmit the actuator movement to the ejection element 51, rests on a lever bearing 18 at the lower end of the actuator chamber 12 and can be tilted about a tilting axis K via this lever bearing 18. A lever arm of the lever 16 projects through an opening 15 into the action chamber 13. The opening 15 thus connects the action chamber 13 with the actuator chamber 12.

[0183] In the action chamber 13, the lever arm has a contact surface 17 pointing towards the plunger 51, which presses against a contact surface 54 of a plunger head 53 ( Figure 3 ). In Figure 1It becomes clear that the contact between piezo actuator 20 and lever 16 occurs in an area between the lever bearing 18 and the contact surface 17 of the lever 16 facing the plunger 51. This contact point is closer to the lever bearing 18 than to the contact surface 17 in order to achieve a desired transmission ratio, where a small movement of the actuator 20 causes a larger movement of the ejector element 51. In the Figure 3 In the illustrated embodiment, the contact surface 17 of the lever 16 is permanently in contact with the contact surface 54 of the plunger head 53, by means of a plunger spring 55 pressing the plunger head 53 against the lever 16 from below. The plunger spring 55 is supported downwards on a plunger centering piece 56.

[0184] The lever 16 rests on the plunger 51. However, there is no fixed connection between the two components 16 and 51. In principle, it would also be possible for a gap to exist between the plunger 51 and the lever 16 in the initial or rest position of the plunger spring 55. To enable a nearly constant preload of the drive system (lever-piezo actuator motion system), the lever 16 is pushed upwards at the end where it comes into contact with the plunger 51 by an actuator spring 19. Figure 3 ).

[0185] For measuring the position and / or movement of the plunger 51, a magnet 85 is arranged on the upper side of the lever 16 pointing away from the plunger 51, which interacts with a Hall sensor 84 in the housing of the dosing system ( Figure 3The Hall sensor 84 and the magnet 85 are arranged here on an imaginary vertical axis corresponding to the longitudinal extent of the plunger 51. By means of this arrangement 84, 85, a predominantly vertical stroke movement of the lever 16 can be detected, whereby a position or movement of the plunger 51 can also be determined.

[0186] In Figure 1It becomes clear that the plunger spring 55 is supported on a plunger bearing 57, to which a plunger seal 58 is attached below. The plunger spring 55 pushes the plunger head 53 away from the plunger bearing 57 in an axial direction upwards. This also pushes a plunger tip 52 away from a sealing seat 63 of the nozzle 60. That is, without external pressure from above on the contact surface 54 of the plunger head 53, the plunger tip 52 is located at a distance from the sealing seat 63 of the nozzle 60 when the plunger spring 55 is in its rest position. Thus, in the rest state (unexpanded state) of the piezo actuator 20, a nozzle opening 61 is also open.

[0187] The metering agent is supplied to the nozzle 60 via a nozzle chamber 62, to which a supply channel 64 leads. The supply channel 64 opens at its other end into the metering agent cartridge 66, which is attached directly to the housing 11 via a coupling point 65, specifically to the second housing part 11b. The metering agent cartridge 66 is detachably fixed to the metering system 1 by means of a cartridge holder 67 and has a compressed air supply 68 at its upper end, for example, to set a specific pressure of the metering agent in the metering agent cartridge 66.

[0188] The fluidic unit 50 further comprises a connecting cable 69 for controlling a heating element (not shown) of the fluidic unit 50. This allows the metering medium to be heated separately within the fluidic unit 50, e.g., differently than in the nozzle 60. Preferably, the metering system 1 can include several heating zones for the metering medium, each with its own independently adjustable temperature. A first heating zone can be assigned to the nozzle 60, a second heating zone to the fluidic unit 50, and a third heating zone to the cartridge 66.

[0189] In the Figures 4 to 6 The essential steps of an adjustment process for setting the plunger's adjustment position are shown schematically. The parts of the metering system shown correspond to those from Figure 1However, these are greatly simplified and enlarged. The dosing system shown here is a "real" system, where the distances between the individual components of the dosing system and their movements during adjustment are greatly enlarged for clarity.

[0190] In Figure 4The figure shows the beginning of the adjustment process. First, the piezo actuator 20 (as the first actuator 20) is controlled so that the maximum electrical control voltage intended for operation of the dosing system is applied to the piezo actuator 20, i.e., the piezo actuator 20 is fully expanded. As already explained, the piezo actuator 20 rests on the lever 16, which in turn is in contact with the plunger 51 at its other end. In a next step, an adjustment start temperature is set in the expansion element 30 (as the second actuator 30). For this purpose, the expansion element 30 can be cooled to a specific temperature so that it contracts at least slightly if it is in a heated state. The piezo actuator 20, however, remains expanded.Since the piezo actuator 20 and the plunger 51 form a single moving unit, the plunger 51 can be moved slightly away from the nozzle 60 as a result of the contraction of the expansion element 30 in an upward direction RS', whereby this process is shown greatly magnified here for clarity. Accordingly, a distance a is established between the plunger tip 52 and the sealing seat 63.

[0191] In a subsequent step ( Figure 5 The expansion element 30 is heated from the initial adjustment temperature. The thermally induced expansion of the expansion element 30 is transmitted via the piezo actuator 20 and the lever 16 to the plunger 51, whereby the plunger 51 is moved in a downward direction RS towards the nozzle 60.

[0192] In Figure 5The figure shows the moment of initial contact, where only a left portion of the plunger tip 52 makes initial contact with the sealing seat 63 of the nozzle 60. The nozzle opening 61 is not yet closed by the plunger 51. Therefore, the plunger position shown here corresponds to an initial contact position of the plunger 51 and not to full contact. It should be noted again that in Figures 4 to 6 a "real" dosing system is shown. In contrast, with an "ideal" dosing system, the initial contact ( Figure 5 ) omitted, whereby the plunger 51 is moved directly into the full contact position ( Figure 6 That is, the initial contact then already corresponds to full contact.

[0193] In Figure 6The plunger 51 is finally arranged in a full-contact position. For this to occur, the expansion element 30 is heated further after initial contact until the plunger 51 essentially "slides" into the nozzle 60 in the downward direction RS, thus achieving full contact. Starting from the initial contact ( Figure 5 The plunger tip 52 "slides" along a left-hand portion of the conical sealing seat 63 until it finally seals the nozzle opening 61 in a ring-like manner (full contact). The piezo actuator 20 remains expanded. Depending on the design of the metering system, the full-contact position of the plunger 51 shown here can correspond to the adjust position of the plunger 51, in which case a specific sealing force is additionally exerted by the plunger on the sealing seat 63.

[0194] Further details of the adjustment process can also be found in the Figures 7a-c to 9 .

[0195] In Figure 7aFigure 7 shows a first section of a control method for controlling a dosing system according to one embodiment of the invention. The method section 7 shown here can be used to adjust the position of the plunger in an adjustment process. Preferably, after an initial initiation, the adjustment process can run fully automatically, e.g., by having the individual process steps executed by the control unit integrated into the dosing system. The adjustment process is described below ( Figures 7 to 9 ) described using an "ideal" non-rigid metering system. This means that full contact between the plunger and nozzle is achieved without prior initial contact.

[0196] In the first step, 7-I., of process section 7, the adjustment process is initiated, for example, by inputting a signal to the dosing system's own control unit or to a central control unit. In step 7-II., the maximum operating deflection of the piezo actuator is set, or the maximum operating electrical control voltage is applied to the piezo actuator. Simultaneously, a trigger for dosing material dispensing is blocked for the duration of the adjustment process. In step 7-III., an adjustment start temperature is set in the expansion element, for example, by cooling. In step 7-IV., the expansion element is then continuously heated from the adjustment start temperature.

[0197] During the heating of the expansion element, the plunger position is measured in relation to the temperature of the expansion element (step 7-V). "Temperature-plunger position" value pairs are continuously generated and stored (step 7-VI). At regular intervals, the system checks whether full contact between the plunger and nozzle has been detected based on these value pairs (step 7-VII). If full contact has not yet been detected, further value pairs are acquired according to the iterative step 7-i. Iterative step 7-i. is repeated until full contact is detected.

[0198] The determination of full contact is carried out in procedure subsection 7-D. This is shown schematically in Figure 8A graph of the change in the plunger position S (in µm) in relation to the increase in the temperature T (in °C) of the expansion element is shown. The plunger position S can be determined, for example, via the distance between the plunger head and the Hall sensor. It can be seen that, starting from the initial adjustment temperature (here at the origin of the coordinate system), a predominantly linear (adjustment) relationship is initially established between the plunger position S and the temperature T of the expansion element. This relationship is represented here as a straight line with a slope m1, where the line is derived from the previously recorded "temperature-plunger position" value pairs.

[0199] Once full contact is established between the plunger and the nozzle, and the plunger is pressed into the nozzle, the plunger position S changes more slowly than before full contact, despite the continuous temperature increase T. Therefore, a new relationship between plunger position S and temperature T is established, which is represented here as a straight line with a shallower slope m2. The plunger position S1, at which the slope of the line changes from m1 to m2, corresponds to the full-contact position S1 of the plunger. The shallow slope m2 results from a slight plunger movement due to elastic deformation of components of the metering system, where the slope m2 can be a measure of the system's spring stiffness. A full-contact temperature T1 is assigned to the full-contact position S1 here.

[0200] The time required to achieve full contact can be approximately 1 minute, for example. It is also conceivable to dynamically heat the expansion element to achieve full contact more quickly. For instance, the expansion element can be heated to varying degrees in different phases, thereby capturing an average slope m1. This calibration could also be performed by the manufacturer and stored in the dosing system.

[0201] As soon as full contact is detected in step 7-VII, the full contact position S 1 of the plunger is stored in step 7-VIII. Figure 7a ).

[0202] In step 7-IX, the slope m1 ( Figure 8) until full contact is reached, preferably depending on the previously determined "temperature-position" value pairs. In step 7-X, the spring stiffness of the metering system can then be determined, e.g., by reading the calibration data stored in the metering system at the factory. Finally, in step 7-XI, the adjustment position of the plunger can be calculated, in particular taking into account the full contact position (S1) and the slope m1 (both Figure 8 ) and the spring stiffness of the overall system. The Adjust position can be calculated, for example, using the previously introduced equation (1). Furthermore, in step 7-XI, an Adjust temperature associated with the Adjust position can be determined.

[0203] The determination of the Adjust position in procedure subsection 7-E is in Figure 9The change in plunger position S (in µm) is shown schematically using a function graph in relation to the increase in temperature T (in °C) of the expansion element. The adjusted position (S₂) of the plunger differs slightly from the full contact position (S₁) of the plunger. This is because the adjusted position (S₂) is shown here for a non-rigid metering system, where a slight plunger movement corresponding to the slope m₂ occurs after full contact (S₁). To generate a specific sealing force despite the slight plunger movement in the adjusted position (S₂), the spring stiffness of the metering system can be taken into account when calculating the adjusted position (S₂). An adjusted temperature (T₂) of the expansion element is assigned to the adjusted position (S₂). The Adjust position (S 2 ) also corresponds to an ejection end position (S 3 ) of the plunger.

[0204] Unlike what is shown here, in a very rigid "ideal" metering system, the adjust position S 2 of the plunger can essentially correspond to the full contact position S 1, i.e., the full contact position (S 1), the adjust position (S 2) and the ejection end position (S 3) then essentially coincide.

[0205] In step 7-XII, the adjust position and the associated adjust temperature are saved ( Figure 7a The control unit is then notified that the adjustment process is complete (step 7-XIII). This allows the trigger for dosing to be unlocked. Finally, in step 7-XIV, the operating mode of the dosing system is checked; that is, a decision is made as to whether the dosing system should switch to standby mode (jump marker A) or to the dosing process (jump marker B).

[0206] In Figure 7bA further section of the control method for controlling the dosing system according to one embodiment of the invention is shown. The method section 8 shown here follows directly after the jump label A. Figure 7a The procedure section 8 is therefore carried out, provided that the query of the operating mode in step 7-XIV. ( Figure 7a ) resulted in the dosing system switching to hold mode.

[0207] In the first step 8-I. ( Figure 7bThe adjusted temperature, determined in a previously performed adjustment process, is retrieved. This temperature is then transmitted to a PID or fuzzy controller in the dosing system (step 8-II). The PID controller can be used to cool (step 8-III) or heat (step 8-IV) the expansion element to set the adjusted temperature within the element (step 8-V). In step 8-VI, the desired actuator or plunger position in the dosing system is set via the expansion element. Process section 8 ends at label C. This is followed by... Figure 7a The operating mode is queried again (step 7-XIV).

[0208] In Figure 7c Another section of the control procedure for controlling the dosing system is shown. Procedure section 9, shown here, follows directly after jump label B. Figure 7aThe procedure section 9 is therefore carried out, provided that the query of the operating mode in step 7-XIV. ( Figure 7a ) resulted in a change of the dosing system to the "active" dosing mode.

[0209] In a first step, 9-I. ( Figure 7cThe electrical control voltage currently applied to the piezo actuator is determined. In step 9-II, it is determined whether the current control voltage corresponds to the quiescent voltage of the piezo actuator, where the piezo actuator is in a rest position, i.e., not expanded. If the current control voltage does not correspond to the quiescent voltage, i.e., the piezo actuator is at least partially expanded, the current operating voltage of the piezo actuator is measured again according to iterative process step 9-iii. Iterative process step 9-iii is repeated until the current control voltage corresponds to the quiescent voltage of the piezo actuator (step 9-II), i.e., until the plunger is in the initial ejection position.

[0210] In step 9-III, starting from the initial ejection position, the change in the electrical actuator voltage and the corresponding plunger position are measured during a single ejection cycle. Preferably, "control voltage-plunger position" value pairs are generated over time for this purpose. In step 9-IV, the electrical control voltage currently applied to the piezo actuator is determined. If the control voltage does not yet correspond to a maximum control voltage (expansion voltage) intended for operation, further value pairs are generated according to the iterative step 9-iv. The iterative step 9-iv is repeated until the current control voltage corresponds to the expansion voltage of the piezo actuator (step 9-IV), i.e., the plunger is in the final ejection position. In step 9-V, the actuator displacement at the sealing position is determined, e.g., based on the generated "control voltage-plunger position" value pairs.Further details regarding this or procedural subsection 9-G will be provided below based on the following. Figures 10 to 12 explained.

[0211] Alternatively or additionally, it is also possible to perform the previously described process, in particular the acquisition of "control voltage-plunger position" value pairs over time, during an opening edge. This can have the advantage that the opening edge is slower than the closing edge, thus achieving even higher measurement accuracy. In this variant, the iterative substep 9-iii can be repeated until a maximum control voltage (expansion voltage) intended for operation is applied to the piezo actuator, at which point the piezo actuator reaches its maximum possible deflection during operation (step 9-II). In step 9-III, starting from the plunger's end-extension position, the change in the electrical actuator voltage over time and the plunger position corresponding to the respective actuator voltage are measured during a single plunger retraction movement.Preferably, "control voltage-piston position" value pairs are generated over time. In step 9-IV, the electrical control voltage currently applied to the piezo actuator is determined. If the control voltage does not yet correspond to the quiescent voltage of the piezo actuator, further value pairs are generated according to the iterative step 9-iv. The iterative step 9-iv. is repeated until the current control voltage corresponds to the quiescent voltage of the piezo actuator (step 9-IV), i.e., the piston is in the initial ejection position. In step 9-V, the actuator displacement at the sealing position is determined, e.g., based on the generated "control voltage-piston position" value pairs.

[0212] The following section describes procedure subsection 9-G separately for the different types of dosing systems. Figure 10Procedure subsection 9-G is shown for an "ideal" very rigid metering system. The upper part schematically shows a function graph of the time course of the electrical control voltage U (in V) applied to the piezo actuator over time t (in arbitrary units). The lower part of Figure 10 The plunger position S (in µm) corresponding to the control voltage (U) is shown for the same period.

[0213] At the start of the recording, a voltage U1 is applied to the piezo actuator, corresponding to its expansion voltage; that is, the piezo actuator is initially expanded. During the same period, the plunger is in the ejection end position S3, which here simultaneously corresponds to the full contact position S1' and the adjustment position S2'. As a result of a reduction in the control voltage U, the plunger moves away from the nozzle at time t0, thus clearing the nozzle opening. At time t1, the control voltage U2 corresponds to the quiescent voltage of the piezo actuator; that is, the piezo actuator is no longer expanded. Accordingly, the plunger is temporarily in the ejection start position S5. The control algorithm for adjusting the ejection end position S3 to the adjustment position S2' can, as mentioned, be executed during each opening and / or closing edge.The following describes the control process during a closing edge, i.e., starting at time t 2 .

[0214] At time t₂, i.e., at the beginning of the ejection process, an electrical control voltage U is applied to the piezoelectric actuator. The control voltage U is continuously increased, resulting in a predominantly linear relationship between control voltage U and time t (upper part of Figure 10 (Time t2 to t4). With the application of the control voltage U at time t2, the plunger is deflected back towards the nozzle by the expanding piezoelectric actuator. During the period t2 to t3, a first, predominantly constant plunger velocity is established (corresponding to m1'). Accordingly, an initial velocity ratio develops between the change in the control voltage U of the piezoelectric actuator and the resulting plunger velocity.

[0215] At time t3, the plunger velocity decelerates abruptly, establishing a new plunger velocity (corresponding to m4'). In this case, the plunger velocity approaches zero after t3. At time t3, an electrical voltage U3 is applied to the piezo actuator. However, since the control voltage of the piezo actuator continues to increase continuously even after time t3 and beyond U3, a new (velocity) ratio is established between the change in control voltage and the plunger velocity. The time t3, or the plunger position S1', S2', S3 at which the change in the (velocity) ratio occurs, corresponds here to the full-contact position S1' of the plunger. Since this is an "ideal" and very rigid metering system, the full contact position S 1' already corresponds to the ejection end position S 3 and also to the adjust position S 2' of the plunger.

[0216] The electrical control voltage U of the piezo actuator is increased further beyond U 3 until, at time t 4, the expansion voltage U 1 is finally applied to the piezo actuator again.

[0217] Based on the determined full-contact position S1 and the electrical control voltage U3 of the piezo actuator assigned to this position S1, an actual value representing the sealing position actuator deflection can be determined. In this case, the value representing the sealing position actuator deflection corresponds to a voltage difference ΔU1 between the maximum electrical control voltage U1 applied to the piezo actuator during operation and the control voltage U3 required to move the plunger to the full-contact position S1. The sealing position actuator deflection ΔU1 determined in this way, i.e., the voltage difference ΔU1 of the control voltage applied to the piezo actuator, causes a sealing force of the plunger against the nozzle to be established from time t3 onwards. That is, the voltage difference ΔU1 is essentially completely converted into a sealing force of the plunger.In contrast, the remaining portion of the control voltage applied to the piezo actuator, i.e. the difference between U 3 and U 2, is converted into a movement of the plunger, resulting in a (hydraulically) effective stroke H 1.

[0218] In Figure 11 Procedure subsection 9-G is shown for an "ideal" non-rigid metering system. Analogous to Figure 10 The upper part shows a schematic function graph of the time course of the electrical control voltage U (in V) applied to the piezo actuator over time t (in arbitrary units), while the lower part shows the plunger position S (in µm) corresponding to the control voltage (U) for the same period.

[0219] At Figure 11The determination of the sealing position actuator deflection is described using an opening flank. At the beginning of the recording, an expansion voltage U1 is again applied to the piezo actuator. At time t0', the electrical control voltage is reduced, whereby the pressure built up in the piezo actuator by the expansion begins to slowly decrease. This means that during this period (t0' to t1'), primarily only the sealing force exerted by the plunger against the nozzle is reduced. The electrical control voltage U is reduced from U1 to U3 during this period (t0' to t1'), where the difference between U1 and U3 corresponds to the sealing position actuator deflection ΔU2.

[0220] During the period t0' to t1', in addition to the reduction of the sealing force, a slight plunger movement occurs, whereby the plunger slowly moves from the ejection end position S3 or the adjustment position S2' to the full contact position S1'. This slight plunger movement, corresponding to the slope m2', is caused by an elastic (reversible) deformation of components of the metering system. The continuously decreasing actuator pressure allows the components compressed during a previous ejection process, e.g., of the fluidic unit, to "relax" or "re-form" and realign themselves according to a non-compressed (target) arrangement. Accordingly, the plunger can return from the ejection end position S3 to the full contact position S1' during this period, whereby the control voltage U of U1 and U3 is reduced.

[0221] The difference ΔU 2 between these two stress values ​​U 1 , U 3 (sealing position-actuator deflection) can therefore be used to a large extent to build up sealing force even in such a non-rigid metering system, whereby a small proportion of the sealing position-actuator deflection is converted into an elastic deformation of components of the metering system (unlike in the completely rigid metering system made of Figure 10 ).

[0222] To still achieve a specific sealing force, the spring stiffness of the overall system can be taken into account or compensated for when calculating the adjust position S 2' (e.g., according to equation 1). For example, the sealing position actuator deflection ΔU 2 can be increased accordingly, which in turn can reduce the (hydraulically) effective stroke H 2.

[0223] During the period t1' to t2', the plunger position changes more rapidly than before, according to a slope m1'. Due to the decreasing actuator voltage U and a spring system in the metering system, the piezoelectric actuator contracts in its longitudinal extension, moving the plunger from the full-contact position S1' back to the initial ejection position S5. At time t3', the control voltage U of the piezoelectric actuator is increased again, deflecting the plunger back towards the nozzle. At time t4', the plunger first reaches the full-contact position S1', and then, after building up a certain sealing force and with a slight movement of the plunger, finally reaches the final ejection position S3 at time t5'. This final ejection position corresponds to the plunger's adjustment position S2' when the metering system is in its regulated state.

[0224] In Figure 12For clarification, procedure subsection 9-G is now shown for a "real" non-rigid metering system using a closing flank, whereby the basic structure of Figure 12 the Figure 10 and 11This corresponds to (time course of the electrical control voltage U above; plunger position S corresponding to the control voltage U below). Starting from the plunger's initial ejection position S5, a continuous increase in the electrical control voltage U applied to the piezo actuator causes the plunger to move towards the nozzle at an initial velocity (corresponding to m1') (period t4" to t5"). At time t5", the plunger velocity decelerates (corresponding to m3'), while the control voltage continues to increase continuously. Consequently, at t5", a new velocity relationship is established between the change in the piezo actuator's control voltage U and the resulting plunger velocity. The reason for the plunger's deceleration at time t5" is initial contact between the plunger and the nozzle, with S4 corresponding to the initial contact position.

[0225] The plunger is deflected beyond S4 against a certain resistance from the nozzle until, at time t6", the plunger has completely "slid" into the nozzle, thus achieving full contact (S1'). The slope m3' therefore represents the plunger's "sliding" into the nozzle, specifically into the full-contact position S1'. To move the plunger from the initial ejection position S5 to the full-contact position S1', an electrical control voltage ΔU4 is required, which results from the difference between U3 and U2 (resting voltage) of the piezoelectric actuator.

[0226] The control voltage difference ΔU4 is a portion of the maximum control voltage U1 applied to the piezo actuator during operation, whereby ΔU4 is almost entirely converted into the (hydraulically) effective stroke H3 of the plunger (and therefore essentially does not contribute to the generation of sealing force). The (hydraulically) effective stroke H3 corresponds here as well to the plunger movement from the initial ejection position S5 to the full contact position S1'.

[0227] At full contact (time t 6"), the (speed) ratio changes again, and the plunger is moved only very slightly (corresponding to m2') to an ejection end position S 3 (time t 7"). The slope m2' is determined as shown by Figure 11 This is explained as being caused by a slight elastic deformation of components of the dosing system. Furthermore, during the period t 6" to t 7", a sealing force of the plunger is predominantly generated via the sealing position actuator deflection ΔU 3.

[0228] Based on the respective determined actual sealing position actuator deflection (actual value ΔU 1 , ΔU 2 , ΔU 3 , hereinafter only ΔU) a step 9-VI. can then be carried out. Figure 7c The system uses a comparison with a target value representing the sealing actuator deflection to determine whether the current sealing actuator deflection (here, the voltage difference ΔU of the control voltage) is lower than the target value. If the query indicates that the target value is undershot, then, according to step 9-VII, the temperature of the expansion element is increased so that the target value of the sealing actuator deflection (here, a specific target voltage difference) is reached.

[0229] Provided the target value is not undershot (step 9-VI), step 9-VIII checks whether the current sealing actuator deflection (here the voltage difference ΔU of the control voltage) exceeds the target value. If necessary, the temperature of the expansion element is then reduced in step 9-IX to adjust the target value of the sealing actuator deflection. If no deviation of the actual value (ΔU) of the sealing actuator deflection from the target value is detected, the process proceeds directly to jump label C without any control of the expansion element. The operating mode is then checked again after jump label C. Figure 7a ; Step 7-XIV.).

[0230] Finally, it should be noted once again that the dosing systems and control methods for dosing systems described in detail above are merely exemplary embodiments which can be modified in various ways by a person skilled in the art without departing from the scope of the invention. For example, in the explained control method, it is not always necessary to carry out all process steps, or the process steps could also be carried out in a different order. Furthermore, the control algorithm can also be executed during the other "opening" or "closing" edge, which is not described in the application. Moreover, the use of the indefinite articles "a" or "an" does not preclude the possibility that the relevant features may be present multiple times. Reference symbol list

[0231] 1 Dosing system 10 Actuator unit 11 Housing 11a, 11b Housing block / Housing components 12 Actuator chamber 13 Action chamber 14 Movement mechanism 15 Opening 16 Lever 17 Lever contact surface 18 Lever bearing 19 Actuator spring 20 First actuator / Piezo actuator 21 Piezo stack 22 Piezo actuator housing 23 Push piece 30 Second actuator / Expansion element 31 Housing (expansion element) 32 Expansion body 33 Heating element (expansion element) 34 Cooling area / Cooling chamber (expansion element) 35 Piston 36 Centering element 40 Cooling device 41 Coupling point Cooling medium supply 42, 42',42 Inlet channel (cooling medium) 43 Proportional valve (expansion element) 44 Proportional valve (piezo actuator) 45 Outlet channel (cooling medium) 46 Coupling point for cooling medium discharge 50 Fluidic unit 51 Discharge element / plunger 52 Plunger tip 53 Plunger head 54 Plunger contact surface 55 Plunger spring 56 Plunger centering piece 57 Plunger bearing 58 Plunger seal 60 Nozzle 61 Outlet opening 62 Nozzle chamber 63 Sealing seat 64 Supply channel 65 Reservoir interface 66 Medium cartridge 67 Cartridge holder 68 Compressed air supply to cartridge 69 Connection cable 70 Coupling mechanism 71 Coupling spring 72 Ball 73 Plug-in coupling part 74 Ball cap 75 Heating unit (nozzle) 80 Control unit (metering system) 81 Control unit connection cable 82 Temperature sensor (medium) 83 Temperature sensor (expansion element) 84 Hall sensor 85 Magnet 7 First process section 7-I. to 7-XIV. Process steps (First process section) 7-i. Iterative process step (First process section) 7-D,7-E Procedural Subsections (First Procedural Section) 8 Second Procedural Section 8-I. to 8-VI. Procedural Steps (Second Procedural Section) 9 Third Procedural Section 9-I. to 9-IX. Procedural Steps (Third Procedural Section) 9-iii., 9-iv. Iterative process steps (Third process section) 9-G Process subsection (Third process section) a Distance (Pushrod tip : Nozzle) m1, m2 Ratio (Pushrod position : Temperature) m1', m2', m3', m4' Ratio (Pushrod position : Time) K Tilting axis H1, H2, H3 (Hydraulic) Effective stroke R Ejection direction RS, RS' Direction of movement of plunger S1, S1', S2, S2', S3, S4, S5 Plunger position t0 - t4 Time points t0' - t5' Time points t0" - t7" Time points T1, T2 Temperature (Expansion element) U1, U2, U3 Voltage (Piezo actuator) ΔU, ΔU1, ΔU 2 , ΔU 3 , ΔU 4 Voltage difference / actual value,

Claims

1. A dosing system (1) for a dosing substance, which dosing system (1) comprising a housing (11) having a nozzle (60) and a feed channel (64) for dosing substance, a discharge element (51) arranged in the housing (11) for discharging dosing substance from the nozzle (60), at least one first actuator (20), preferably a piezo actuator (20), coupled to the discharge element (51) and / or the nozzle (60), and at least one second actuator (30), preferably an expansion material element (30), coupled to the first actuator (20), the second actuator (30) being designed to set a position of the at least one first actuator (20) relative to the housing (11), particularly with respect to the discharge element (51) and / or the nozzle (60), characterized in that the first actuator (20) and the second actuator (30) can be controlled separately.

2. The dosing system according to claim 1, wherein the second actuator (30), particularly the expansion material element (30), is designed and arranged in the housing (11) in order to set a position of the discharge element (51) in relation to the nozzle (60) of the dosing system (1), particularly a distance (a) between a discharge tip (52) of the discharge element (51) and a nozzle opening (61) of the nozzle (60).

3. The dosing system according to claim 1 or 2, having at least one heating device (33) associated with the second actuator (30), particularly the expansion material element (30), and / or at least one cooling device (40) associated with the second actuator (30), particularly the expansion material element (30) and having a control unit (80) for controlling and / or regulating the heating device (33) and / or the cooling device (40).

4. The dosing system according to any one of the preceding claims, wherein the dosing system (1) comprises a sensor arrangement (83, 84) having at least one of the following sensors: - a temperature sensor (83) associated with the second actuator (30), particularly the expansion material element (30), - a temperature sensor associated with the first actuator (20), - a temperature sensor associated with the housing (11), - a movement sensor (84) for determining a movement of the discharge element (51), - a position sensor (84) for determining a position of the discharge element (51).

5. The dosing system according to any one of the preceding claims, wherein the second actuator (30), particularly the expansion material element (30), comprises an expansion body (32) and preferably a transmitter (35) coupled therewith and / or wherein the second actuator (30) is coupled to the first actuator (20) in an axial direction for positioning of the first actuator (20), preferably by means of the transmitter (35).

6. The dosing system according to any one of the preceding claims, wherein the dosing system (1) comprises at least one force sensor in order to determine a force exerted on the first actuator (20), particularly by means of the second actuator (30), particularly preferably by means of the expansion material element (30), preferably in order to capture a sealing force of the discharge element (51) based thereon.

7. A method for controlling a dosing system (1) for a dosing substance according to any one of the preceding claims, wherein the second actuator (30) is controlled and / or regulated in order to set a position of the at least one first actuator (20) relative to the housing (11), particularly with respect to the discharge element (51) and / or the nozzle (60).

8. The method for controlling a dosing system according to claim 7, wherein for controlling and / or regulating the second actuator (30), particularly the expansion material element (30), a temperature of the second actuator (30), particularly a temperature of the expansion material element (30), is controlled and / or regulated, preferably by means of at least one heating device (33) associated with the second actuator (30) and / or by means of at least one cooling device (40) associated with the second actuator (30).

9. The method for controlling a dosing system according to claim 7 or 8, wherein the second actuator (30), particularly the expansion material element (30), is controlled and / or regulated such that the discharge element (51) is brought to an adjust position (S2, S2') of the discharge element (51) during a defined operating state, in which preferably the discharge tip (52) of the discharge element (51) has a certain pressing force into the nozzle (60).

10. The method for controlling a dosing system according to any one of the preceding claims 7 to 9, wherein for controlling and / or regulating the second actuator (30), preferably for controlling and / or regulating the expansion material element (30), particularly for setting an adjust position (S2, S2'), at least one of the following operating parameters of the dosing system (1) is taken into account: - a temperature of the second actuator (30), particularly a temperature of the expansion material element (30), particularly preferably a temperature of an expansion body (32), - a position of the discharge element (51) in the dosing system (1), particularly a position of a lever (16) coupled to the discharge element (51), - a deflection of the first actuator (20), preferably an activation signal of the actuator (20), - a temperature of the first actuator (20), - a temperature of the housing (11), - an amount and / or a weight of the dosing substance to be dispensed from the dosing system (1) during a respective discharge process, - a signal from a flow sensor for dosing substance, - calibration data of the dosing system (1), - a sealing force.

11. The method for controlling a dosing system according to any one of the preceding claims 9 or 10, wherein the second actuator (30), particularly the expansion material element (30), is controlled and / or regulated such that a discharge end position (S3) of the discharge element (51) during operation of the dosing system (1) corresponds to an adjust position (S2, S2') determined in a previously performed adjustment process.

12. The method for controlling a dosing system according to claim 11, wherein in an adjustment process for setting the adjust position (S2, S2') of the discharge element (51), a regulation algorithm having at least the following steps is run through: - setting a maximum deflection of the first actuator (20), - setting an adjustment start temperature of the second actuator (30), particularly an adjustment start temperature of the expansion material element (30), preferably by means of cooling the expansion material element (30), - heating the second actuator (30), particularly heating the expansion material element (30), until full contact is detected between the discharge element (51) and the nozzle (60) and a full contact position (S1, S1') of the discharge element (51) is determined and / or a full contact temperature (T1) which is associated with the full contact position (S1, S1'), and / or heating the second actuator (30), particularly heating of the expansion material element (30), until a maximum system deflection of the first actuator (20) and the second actuator (30) is reached and a system end contact position of the discharge element (51) is determined and / or a system end contact temperature which is associated with the system end contact position, - determining an adjust position (S2, S2') of the discharge element and / or an adjust temperature (T2) which is associated with the adjust position (S2, S2'), wherein to determine the adjust position (S2, S2') and / or the adjust temperature (T2), the full contact position (S1, S1') of the discharge element (51) and / or the full contact temperature (T1) or the system end contact position of the discharge element (51) and / or the system end contact temperature and optionally at least one adjust parameter are taken into account, - optionally transferring the discharge element (51) to the adjust position (S2, S2').

13. The method for controlling a dosing system according to claim 11 or 12, wherein a regulation algorithm having at least the following steps is run through to regulate the discharge end position (S3) during operation: - setting a discharge end position (S3) of the discharge element (51), - determining a position of the discharge element (51) as a function of a deflection of the first actuator (20) during a retraction movement of the discharge element (51), particularly as a function of an electrical control voltage (U) applied to the first actuator (20), - determining an actual value (ΔU) of a value representing a sealing position actuator deflection, wherein the discharge element (51) in the sealing position actuator deflection is pressed by a certain minimum beyond the full contact between the discharge element (51) and the nozzle (60) into a sealing seat (63) of the nozzle (60), - controlling and / or regulating the second actuator (30), preferably controlling and / or regulating the expansion material element (30), particularly as a function of a difference between the actual value (ΔU) of the value representing the sealing position actuator deflection and a target value of the value representing the sealing position actuator deflection, for setting the target value of the value representing the sealing position actuator deflection, wherein the target value of the value representing the sealing position actuator deflection is associated with the adjust position (S2, S2') of the discharge element (51).

14. The method for controlling a dosing system according to claim 13, wherein a temperature of the second actuator (30), particularly a temperature of the expansion material element (30), in the event of a positive deviation of the actual value (ΔU) of the value representing the sealing position actuator deflection from the target value of the value representing the sealing position actuator deflection is reduced and / or wherein the temperature of the second actuator (30), particularly the temperature of the expansion material element (30), in the event of a negative deviation of the actual value (ΔU) of the value representing the sealing position actuator deflection from the target value of the value representing the sealing position actuator deflection is increased.

15. The method for controlling a dosing system according to claim 13 or 14, wherein during operation of the dosing system (1) at regular intervals, preferably with each discharge process of the discharge element (51), a difference between the actual value (ΔU) of the value representing the sealing position actuator deflection and the target value of the value representing the sealing position actuator deflection is determined.

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