DOSING SYSTEM HAVING AN ADJUSTABLE ACTUATOR

Abstract

The invention relates to dosing system (1) for a dosing substance, which dosing system (1) comprises 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) is 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). The invention further relates to a method for controlling such a dosing system (1).

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).

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, 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 claim 1, 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 claim 1, 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 claim 1, 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, 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), 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, 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 (S.sub.2, S.sub.2′) 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 claim 7, 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 (S.sub.2, S.sub.2′), 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 claim 9, wherein the second actuator (30), particularly the expansion material element (30), is controlled and/or regulated such that a discharge end position (S.sub.3) of the discharge element (51) during operation of the dosing system (1) corresponds to an adjust position (S.sub.2, S.sub.2′) 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 (S.sub.2, S.sub.2′) 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, 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 (S.sub.1, S.sub.1′) of the discharge element (51) is determined and/or a full contact temperature (T.sub.1) which is associated with the full contact position (S.sub.1, S.sub.1′), 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 (S.sub.2, S.sub.2′) of the discharge element and/or an adjust temperature (T.sub.2) which is associated with the adjust position (S.sub.2, S.sub.2′), wherein to determine the adjust position (S.sub.2, S.sub.2′) and/or the adjust temperature (T.sub.2), the full contact position (S.sub.1, S.sub.1′) of the discharge element (51) and/or the full contact temperature (T.sub.1) 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 (S.sub.2, S.sub.2′).

13. The method for controlling a dosing system according to claim 11, wherein a regulation algorithm having at least the following steps is run through to regulate the discharge end position (S.sub.3) during operation: setting a discharge end position (S.sub.3) 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 (S.sub.2, S.sub.2′) 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, 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.

Description

[0168] The invention is explained in more detail below with reference to the accompanying figures on the basis of embodiments. The same components are provided with identical reference numbers in the various figures. The figures are usually not to scale. They show schematically:

[0169] FIG. 1 a view shown in section of a dosing system according to an embodiment of the invention,

[0170] FIGS. 2 and 3 parts of the dosing system from FIG. 1 in an enlarged view,

[0171] FIGS. 4 to 6 parts of the dosing system from FIG. 1 in a further enlarged and greatly simplified view,

[0172] FIGS. 7a to 7c flow charts of sections of a method for controlling the dosing system according to an embodiment of the invention,

[0173] FIGS. 8 to 12 representations of function graphs to illustrate subsections of the method according to FIGS. 7a to 7c for controlling the dosing system.

[0174] A specific embodiment of a dosing system 1 according to the invention will now be described with reference to FIG. 1. The dosing system 1 is shown here in the usual intended position, for example, during operation of the dosing system 1. A nozzle 60 is located in the lower region of the dosing system 1, such that the drops of the medium are discharged in a discharge direction R through the nozzle 60 downwards. Insofar as the terms below and above are used in the following, this information therefore always relates to such a, usually conventional, position of the dosing system 1. However, this does not rule out the fact that the dosing system 1 can also be used in another position in special applications and the drops, for example, are discharged laterally. Depending on the medium, pressure and exact construction and activation of the entire discharge system, this is basically also possible. Since the basic structure of dosing systems is known, for the sake of clarity, it is predominantly those components that relate at least indirectly to the invention that are shown here.

[0175] The dosing system 1 comprises, as essential components, an actuator unit 10 and a fluidic unit 50 coupled thereto. The dosing system 1 shown here further comprises a dosing substance cartridge 66 which is coupled to the fluidic unit 50.

[0176] In the embodiment shown here, the actuator unit 10 and the fluidic unit 50 are implemented in the manner of plug-in coupling parts that can be coupled to one another to form a quick-release coupling. Advantageously, the actuator unit 10 and the fluidic unit 50 can thus be coupled to one another without tools in order to form the dosing system 1. The quick-release coupling comprises a coupling mechanism 70 having a coupling spring 71 which keeps a sphere 72 under constant pretension. The coupling spring 71 and the sphere 72 are here encompassed by a (first) housing block 11a and form a first plug-in coupling part. The first plug-in coupling part furthermore comprises a heating device 75 for heating the dosing substance in the nozzle 60.

[0177] The coupling mechanism 70 has a number of spherical caps 74 (only one shown here) into which the sphere 72 can engage for coupling. The spherical caps 74 are arranged in a second plug-in coupling part 73 of the fluidic unit 50, wherein the fluidic unit 50 is encompassed by a (second) housing block 11b. For coupling, the first plug-in coupling part and the second plug-in coupling part can be plugged into one another along a (virtual or imaginary) plug-in axis and thereby coupled to one another. For example, the fluidic unit 50 can be plugged into the actuator unit 10 against a direction R and coupled to the actuator unit 10 in a suitable rotational position.

[0178] The spherical caps 74 are arranged in the second plug-in coupling part 73 of the fluidic unit 50 such that different latching positions are possible, that is, different rotational positions of the fluidic unit 50 about the plug-in axis are possible. Due to the resiliently pretensioned sphere 72, the plug-in coupling part 73 engages in one of the several possible latching positions in order to form the dosing system 1. It should be noted, however, that the respective assemblies 10, 50 can also be fixedly connected to one another, for example, by means of a fixing screw, so as to form the housing 11 with the two housing blocks 11a, 11b.

[0179] In the embodiment shown here, the actuator unit 10 comprises two internal chambers, namely, on the one hand, an actuator chamber 12 having a piezo actuator 20 located therein and, on the other hand, an action chamber 13 into which a movable discharge element 51, here a plunger 51, of the fluidic unit 50 protrudes. Via a movement mechanism 14 having a lever 16 which protrudes from the actuator chamber 12 into the action chamber 13, the plunger 51 is actuated by means of the piezo actuator 20 such that the fluidic unit 50 discharges the medium to be dosed in the desired amount at the desired time.

[0180] The piezo actuator 20 is connected electrically or in terms of signal technology to an external control unit (not shown) in order to be activated. The piezo actuator 20 here comprises an actuator housing 22 and a piezo stack 21 hermetically encapsulated therein with respect to the environment. The piezo actuator 20 can expand and contract again in the longitudinal direction of the actuator chamber 12 in accordance with a circuit by means of the control unit. Since the basic function and activation of piezo actuators is known, this will not be discussed further.

[0181] 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 indirectly in operative contact with an expansion material element 30 (as the second actuator 30). The expansion material element 30 here comprises a housing 31 which encloses a cylindrical expansion body 32 from five sides (in cross section from three sides). The housing 31 is designed such that a thermal expansion movement of the expansion body 32 is directed predominantly in the direction of the piezo actuator 20.

[0182] The expansion body 32 adjoins a transmitter 35 on the side on which the expansion body 32 is not delimited by the chamber 31. The transmitter 35 is movably mounted in the housing 31 of the expansion material element 30 and can be displaced in the direction of a longitudinal extension of the piezo actuator 20. On a side of the transmitter piston 35, which is lower here, this adjoins the piezo actuator 20 or rests directly on an outside of the actuator housing 22. This means that the expansion body 32, the transmitter 35 and the piezo actuator 20 are in operative contact with one another such that a stroke of the expansion body 32 can predominantly be used completely for positioning the piezo actuator 20. The piezo actuator 20 can therefore be moved “up” or “down” by means of the expansion material element 30, which essentially corresponds to a discharge direction R of the dosing substance from the nozzle.

[0183] A nominal stroke of such an arrangement, that is, the extent of a possible displacement of the piezo actuator 20, depends particularly on the diameter of the expansion material element 30 used and the volume of expansion material enclosed therein, and the usable temperature range and the respective coefficient of expansion of the surrounding housing 31, which, for example, can be made of metal or ceramic, and the expansion material element 30. For thermal compensation measures, a design for a nominal stroke in the range, which can correspond to a few micrometers up to a few hundredths of a millimeter, of a piezo actuator nominal stroke or less makes sense. A nominal stroke of the expansion material element 30 of at least 10 μm, preferably of at least 50 μm and particularly preferably of at least 100 μm is provided for the combination of thermal adjust and thermal compensation described here.

[0184] The expansion material element 30 comprises a heating device 33 to control the expansion length of the expansion body 32. This is particularly clear in FIG. 2. The heating device 33 here is a heating foil 33 which rests on an outside of the housing 31 of the expansion material element 30. A temperature sensor 83 for determining a temperature of the expansion material element 30 is further arranged on the outside of the housing 31. The expansion material element 30, particularly the heating device 33, is connected by means of connection cables 81 to a “dosing system-specific” control unit 80 (FIG. 1) for activation.

[0185] The “dosing system-specific” control unit 80 is implemented here (FIG. 1) as a sub-control unit of a central external control unit (not shown) and is coupled thereto for signaling purposes by means of connection cables 81. The sub-control unit 80 can, for example, can be implemented by means of a circuit board 80 in the housing 11 of the dosing system 1. The “dosing system-specific” control unit 80 is designed to control the expansion material element 30 during operation, that is, particularly to apply corresponding control signals to the heating device 33 and a cooling device 40 in order to set a desired expansion of the expansion body 32.

[0186] The dosing system 1 from FIG. 1 further comprises a cooling device 40, wherein the cooling device 40 is designed to cool the expansion material element 30 and the piezo actuator 20 separately. The cooling device 40 here comprises some components that are used jointly for cooling the expansion material element 30 and the piezo actuator 20. This includes, among other things, a coupling point 41, for example, a connection for an external cooling medium supply, an adjoining inflow channel 42 for cooling medium and a cooling medium discharge 46.

[0187] However, the cooling device 40 comprises two separate proportional valves 43, 44 which can be activated separately by the control unit 80. The proportional valve 43 associated with the expansion material element 30 is connected to a cooling region 34 by means of a separate bore 42′. The cooling region 34 here surrounds the expansion material element 30 in a ring shape and is provided exclusively for cooling the expansion material element 30. The cooling region 34 can be flooded with cooling medium, for example, compressed and/or cooled air, via the proportional valve 43 and the bore 42′, in order to cool the expansion material element 30 as required.

[0188] The cooling of the piezo actuator 20 can be controlled separately by means of the second proportional valve 44, wherein the actuator chamber 12 can be supplied with cooling medium via an inflow channel 42″. The cooling of the expansion material element 30 and the piezo actuator 20 is therefore largely thermally decoupled here. The cooling medium can be discharged from the cooling region 34 or from the actuator chamber 12 via a separate outflow channel (not shown here) and then flow out of the dosing system 1 again via a jointly used outflow channel 45 and a coupling point 46 for cooling medium discharge.

[0189] In order to be able to position the piezo actuator 20 in the desired manner by means of the expansion material element 30 during operation, an active unit comprising expansion material element 30 and piezo actuator 20 is kept under constant pretension for coupling. For this purpose, the expansion material element 30 comprises a centering element 36, which is supported on the expansion material element 30 here above (FIG. 1). The centering element 36 is supported with respect to the housing 11 of the dosing system 1 and is designed to exert a certain pressure on the expansion material element 30 and thus also on the piezo actuator 20. The piezo actuator 20 is supported at its lower end via a pressure piece 23 on a lever 16 of the movement mechanism 14.

[0190] The lever 16 of the movement mechanism 14, which is used to transmit the actuator movement to the discharge 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 protrudes through a breakthrough 15 into the action chamber 13. The breakthrough 15 thus connects the action chamber 13 to the actuator chamber 12.

[0191] In the action chamber 13, the lever arm has a contact surface 17 which points in the direction of the plunger 51 and which presses on a contact surface 54 of a plunger head 53 (FIG. 3). In FIG. 1, it becomes clear that the contact between piezo actuator 20 and lever 16 takes place in a region between the lever bearing 18 and the contact surface 17 of the lever 16 pointing to the plunger 51, wherein this contact point lies closer to the lever bearing 18 than the contact surface 17 in order to achieve the desired transmission ratio in which a small movement of the actuator 20 causes a larger movement of the discharge element 51. In the embodiment shown in FIG. 3, it is provided that the contact surface 17 of the lever 16 is permanently in contact with the contact surface 54 of the plunger head 53 in that a plunger spring 55 presses the plunger head 53 against the lever 16 from below. The plunger spring 55 is supported here downward on a plunger centering piece 56.

[0192] The lever 16 rests on the plunger 51. However, there is no fixed connection between the two components 16, 51. In principle, however, it would also be possible for the plunger spring 55 to be at a distance between the plunger 51 and the lever 16 in an initial or rest position. In order to enable an almost constant pretension of the drive system (lever-piezo actuator movement system), the lever 16 is pressed upwards by an actuator spring 19 at the end at which it comes into contact with the plunger 51 (FIG. 3).

[0193] To measure the position and/or movement of the plunger 51, a magnet 85 is arranged here on an upper side of the lever 16 pointing away from the plunger 51 and interacts with a Hall sensor 84 in the housing of the dosing system (FIG. 3). The Hall sensor 84 and the magnet 85 are arranged here on an imaginary vertical axis corresponding to the longitudinal extension of the plunger 51. A predominantly vertical stroke movement of the lever 16 can be captured by means of this arrangement 84, 85, wherein a position or movement of the plunger 51 is also able to be determined.

[0194] In FIG. 1, it becomes clear that the plunger spring 55 is supported on a plunger bearing 57, to which a plunger seal 58 adjoins at the bottom. The plunger spring 55 presses the plunger head 53 away from the plunger bearing 57 in the axial direction upwards. A plunger tip 52 is thus also pressed 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 in the rest position of the plunger spring 55. A nozzle opening 61 is thus also not closed in the rest state (non-expanded state) of the piezo actuator 20.

[0195] The dosing substance is supplied to the nozzle 60 via a nozzle chamber 62 to which a feed channel 64 leads. At its other end, the feed channel 64 opens into the dosing substance cartridge 66, wherein the cartridge 66 is fastened directly to the housing 11 via a coupling point 65, here on the second housing part 11b. The dosing substance cartridge 66 is releasably fixed to the dosing system 1 by means of a cartridge holder 67 and has a compressed air supply 68 at the upper end here, for example, to set a certain pressure of the dosing substance in the dosing substance cartridge 66.

[0196] The fluidic unit 50 further has a connection cable 69 in order to activate a heating device (not shown) of the fluidic unit 50. In addition, the dosing substance can be temperature controlled separately in the fluidic unit 50, for example, other than in the nozzle 60. The dosing system 1 can preferably comprise a plurality of differently temperature-controllable heating zones for the dosing substance, wherein a first heating zone can be associated with the nozzle 60, a second heating zone with the fluidic unit 50 and a third heating zone with the cartridge 66.

[0197] The essential steps of an adjustment process for setting an adjust position of the plunger are shown schematically in FIGS. 4 and 6. The parts of the dosing system shown correspond to those from FIG. 1, but are shown greatly simplified and enlarged. The dosing system shown here is a “real” system, wherein the distances between the individual components of the dosing system and their movements during adjustment are shown greatly enlarged for clarity.

[0198] A start of the adjustment process is shown in FIG. 4. First, the piezo actuator 20 (as the first actuator 20) is activated such that a maximum electrical control voltage provided during operation of the dosing system is applied to the piezo actuator 20, that is, 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 at its other end with the plunger 51. In a next step, an adjustment start temperature is set in the expansion material element 30 (as the second actuator 30). For this purpose, the expansion material element 30 can be cooled to a certain temperature, such that the expansion material element 30 contracts at least slightly if it is in a heated state. The piezo actuator 20, however, is still expanded as before. Since the piezo actuator 20 and the plunger 51 form a movement unit, the plunger 51 can be moved slightly away from the nozzle 60 in an upward direction RS' as a result of the contraction of the expansion material element 30, this process being shown here, as said, greatly enlarged for the sake of clarity. Accordingly, a distance a is established between the plunger tip 52 and the sealing seat 63.

[0199] In a subsequent step (FIG. 5), the expansion material element 30 is heated starting from the adjustment start temperature. The thermally induced expansion of the expansion material element 30 is transmitted to the plunger 51 via the piezo actuator 20 and the lever 16, wherein the plunger 51 is moved in a downward direction RS in the direction of the nozzle 60.

[0200] In FIG. 5, the moment of initial contact is specifically shown, wherein only a left region of the plunger tip 52 makes contact with the sealing seat 63 of the nozzle 60 for the first time. The nozzle opening 61 is not yet closed by the plunger 51. The plunger position shown here therefore corresponds to an initial contact position of the plunger 51 and not a full contact. It should be pointed out again that a “real” dosing system is shown in FIGS. 4 to 6. In contrast to this, in the case of an “ideal” dosing system, the initial contact (FIG. 5) can be omitted, wherein the plunger 51 is moved directly into the full contact position (FIG. 6). That is, the initial contact then already corresponds to the full contact.

[0201] Finally, in FIG. 6, the plunger 51 is arranged in a full contact position. For this purpose, the expansion material element 30 is heated further after the initial contact until the plunger 51 “slides” essentially in the downward direction RS into the nozzle 60, wherein full contact is achieved. Starting from the initial contact (FIG. 5), the plunger tip 52 “slides” along a left part of the conical sealing seat 63 until the plunger tip 52 finally seals the nozzle opening 61 in a ring (full contact). The piezo actuator 20 is still expanded as before. The full contact position of the plunger 51 shown here can, depending on the configuration of the dosing system, correspond to the adjust position of the plunger 51, wherein a certain sealing force additionally is exerted by the plunger on the sealing seat 63 in the adjust position.

[0202] Further details of the adjustment process can also be found in FIGS. 7a-c to 9.

[0203] FIG. 7a shows a first section of a control method for controlling a dosing system according to an embodiment of the invention. Procedure step 7 shown here can be used to set the adjust position of the plunger in an adjustment process or adjust process. The adjustment process can preferably run fully automatically after initial initiation, for example, in that the individual method steps are processed by the “dosing system-specific” control unit. The adjust process is described below (FIGS. 7 to 9) using an “ideal” non-rigid dosing system. This means that full contact between the plunger and nozzle is achieved without prior initial contact.

[0204] In a first step 7-I. of procedure step 7, the adjustment process is started, for example, by means of an input to the “dosing system-specific” control unit or to a central control unit. In step 7-II., a maximum deflection of the piezo actuator during operation is initially set or a maximum electrical control voltage provided during operation is applied to the piezo actuator. At the same time, a trigger for dispensing the dosing substance is blocked for the duration of the adjust process. In step 7-III., an adjustment start temperature is set in the expansion material element, for example, by means of cooling. In step 7-IV., the expansion material element is then continuously heated starting from the adjustment start temperature.

[0205] The plunger position is measured in relation to the temperature of the expansion material element (step 7-V.) during the heating of the expansion material element. “Temperature-plunger position” value pairs are continuously formed and stored (step 7-VI.). A check is carried out at regular intervals on the basis of the value pairs to determine whether full contact between the plunger and nozzle has already been detected (step 7-VII.). If full contact has not yet been detected, further value pairs are captured according to iterative step 7-i. Iterative step 7-i. is run through until a full contact is detected.

[0206] The determination of the full contact takes place in the procedure sub-step 7-D. For this purpose, a function graph of the change in the plunger position S (in μm) in relation to the rise in temperature T (in ° C.) of the expansion material element is shown schematically in FIG. 8. The plunger position S, for example, can be determined via a distance between the plunger head and Hall sensor. It can be seen that, based on the adjustment start temperature (here at the origin of the coordinate system), a predominantly linear (adjustment) ratio is initially established between the plunger position S and the temperature T of the expansion material element. The ratio is shown here as a straight line having a slope m1, wherein the straight line results from the previously captured “temperature-plunger position” value pairs.

[0207] As soon as there is full contact between the plunger and nozzle and the plunger is pressed into the nozzle, the plunger position S changes more slowly than before full contact despite the continuous temperature rise T. A new ratio is therefore established between the plunger position S and temperature T, which ratio is shown here as a straight line having a flatter slope m2. The plunger position S.sub.1, at which the slope of the straight line changes from m1 to m2, corresponds to the full contact position S.sub.1 of the plunger. The flat slope m2 results from a slight movement of the plunger due to an elastic deformation of components of the dosing system, wherein the slope m2 can be a measure of the spring stiffness of the system. The full contact position S.sub.1 is associated with a full contact temperature T.sub.1 here.

[0208] The duration until full contact is reached can be, for example, in about 1 minute. It is also conceivable to heat the expansion material element dynamically in order to achieve full contact more quickly. For example, the expansion material element can be heated to different degrees in different phases, wherein a mean slope m1 is then able to be captured. This calibration could also be carried out by the manufacturer and stored in the dosing system.

[0209] As soon as the full contact in step 7-VII. is detected, the full contact position S.sub.1 of the plunger in step 7-VIII. is stored (FIG. 7a).

[0210] In step 7-IX., the slope m1 (FIG. 8) can then be determined until full contact is reached, preferably as a function of the previously determined “temperature-position” value pairs. In step 7-X., the spring stiffness of the dosing system can then be determined, for example, by reading out the calibration data stored in the dosing system at the factory. In step 7-XI., the adjust position of the plunger can finally be calculated, particularly taking into account the full contact position (S.sub.1), the slope m1 (both in FIG. 8) and the spring stiffness of the overall system. The calculation of the adjust position is possible, for example, using the previously introduced equation (1). Furthermore, in step 7-XI., an adjust temperature that is associated with the adjust position can be determined.

[0211] The determination of the adjust position in procedure sub-step 7-E is shown schematically in FIG. 9 using a function graph of the change in the plunger position S (in μm) in relation to the increase in temperature T (in ° C.) of the expansion material element. The adjust position (S.sub.2) of the plunger differs slightly here from the full contact position (S.sub.1) of the plunger.

[0212] The reason is that the adjust position (S.sub.2) is shown here for a non-rigid dosing system, wherein after full contact (S.sub.1), there is still a slight plunger movement corresponding to the slope m2. In order to build up a certain sealing force despite the slight plunger movement into the adjust position (S.sub.2), the spring stiffness of the dosing system can be taken into account when calculating the adjust position (S.sub.2). The adjust position (S.sub.2) is associated with an adjust temperature (T.sub.2) of the expansion material element. The adjust position (S.sub.2) here also corresponds to a discharge end position (S.sub.3) of the plunger.

[0213] In contrast to what is shown here, the adjust position S.sub.2 of the plunger can essentially correspond to the full contact position S.sub.1 in a very rigid “ideal” dosing system, that is, the full contact position (S.sub.1), the adjust position (S.sub.2) and the discharge end position (S.sub.3) then essentially coincide.

[0214] The adjust position and the associated adjust temperature are stored (FIG. 7a) in step 7-XII. It is then reported to the control unit that the adjustment process has ended (step 7-XIII.). With this, the blockade of the trigger of the dispensing of dosing substance can be removed. In step 7-XIV., the operating mode of the dosing system is finally queried, that is, a decision is made as to whether the dosing system should switch to a standby mode (jump label A.) or switch to the dosing process (jump label B.).

[0215] FIG. 7b shows a further section of the control method for controlling the dosing system according to an embodiment of the invention. Procedure step 8 shown here follows directly on to the jump label A. from FIG. 7a. Procedure step 8 is therefore carried out if the query of the operating mode in step 7-XIV. (FIG. 7a) has resulted in a change of the dosing system into hold mode.

[0216] In the first step 8-I. (FIG. 7b), the adjust temperature determined in a previously carried out adjustment process is called up. The adjust temperature is transmitted to a PID controller or fuzzy controller of the dosing system (step 8-II.). The expansion material element can be cooled (step 8-III.) or heated (step 8-IV.) by means of the PID controller in order to set the adjust temperature in the expansion material element (step 8-V.). In step 8-VI., the desired actuator position or plunger position is set in the dosing system via the expansion material element. Procedure step 8 ends at jump label C. This is followed again by the query of the operating mode in FIG. 7a (step 7-XIV.).

[0217] A further section of the control method for controlling the dosing system is shown in FIG. 7c. Procedure step 9 shown here follows directly on to the jump label B. from FIG. 7a. Procedure step 9 is therefore carried out if the query of the operating mode in step 7-XIV. (FIG. 7a) has resulted in a change of the dosing system to the “active” dosing mode.

[0218] In a first step 9-I. (FIG. 7c), the 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 a no-load voltage of the piezo actuator, wherein the piezo actuator is in a rest position, that is, is not expanded. If the current control voltage does not correspond to the open-circuit voltage, that is, the piezo actuator is at least partially expanded, the current operating voltage of the piezo actuator is measured again corresponding to the iterative process step 9-iii. The iterative process step 9-iii. is run through until the current control voltage corresponds to the open-circuit voltage of the piezo actuator (step 9-II.), that is, until the plunger is in the discharge start position.

[0219] In step 9-III., starting from the discharge start position during a single discharge process, the change in electrical actuator voltage over time and the plunger position corresponding to the respective actuator voltage are measured. For this purpose, “control voltage-plunger position” value pairs are preferably formed over time. The electrical control voltage currently applied to the piezo actuator is determined in step 9-IV. If the control voltage does not yet correspond to a maximum control voltage (expansion voltage) provided during operation, value pairs continue to be formed according to the iterative step 9-iv. The iterative step 9-iv. is run through until the current control voltage corresponds to the expansion voltage of the piezo actuator (step 9-IV.), that is, the plunger is in the discharge end position. In step 9-V., the sealing position actuator deflection is determined, for example, on the basis of the formed “control voltage-plunger position” value pairs. Further details on this or on procedure sub-step 9-G are explained below with reference to FIGS. 10 to 12.

[0220] Alternatively or additionally, it is also possible to carry out the process described above, particularly the capturing of “control voltage-plunger position” value pairs over time, with an opening gradient. This can have the advantage that the opening gradient proceeds more slowly than the closing gradient, wherein an even higher measurement accuracy can be achieved. In this variant, the iterative sub-step 9-iii. can be run through until a maximum control voltage (expansion voltage) provided during operation is applied to the piezo actuator, wherein the piezo actuator reaches its greatest possible deflection during operation (step 9-II.). In step 9-III., then, starting from the discharge end position of the plunger, the change in the electrical actuator voltage over time and the plunger position corresponding to the respective actuator voltage are measured during a single retraction movement of the plunger. For this purpose, “control voltage-plunger position” value pairs are preferably formed over time. The electrical control voltage currently applied to the piezo actuator is determined in step 9-IV. If the control voltage does not yet correspond to the open-circuit voltage of the piezo actuator, value pairs continue to be formed according to the iterative step 9-iv. The iterative step 9-iv. is run through until the current control voltage corresponds to the open-circuit voltage of the piezo actuator (step 9-IV.), that is, the plunger is in the discharge start position. In step 9-V., the sealing position actuator deflection is determined, for example, on the basis of the formed “control voltage-plunger position” value pairs.

[0221] Procedure sub-step 9-G is described separately below for the different types of dosing systems. In FIG. 10, the procedure sub-step 9-G is shown for an “ideal” very rigid dosing system. In the upper part here, a function graph of the time profile of the electrical control voltage U (in V) applied to the piezo actuator is shown schematically over time t (in arbitrary units). In the lower part of FIG. 10, the plunger position S (in μm) corresponding to the control voltage (U) is shown for the same time period.

[0222] At the beginning of the recording, a voltage U.sub.1 is applied to the piezo actuator, which voltage corresponds to the expansion voltage of the piezo actuator, that is, the piezo actuator is initially expanded. Correspondingly, the plunger is arranged in the discharge end position S.sub.3 during the same time period, which here simultaneously corresponds to the full contact position S.sub.1′ and the adjust position S.sub.2′. As a result of a reduction in the control voltage U, the plunger moves away from the nozzle at time t.sub.0 and thus releases the nozzle opening. At time t.sub.1, control voltage U.sub.2 corresponds to the open-circuit voltage of the piezo actuator, that is, the piezo actuator is no longer expanded. Accordingly, the plunger is temporarily in the discharge start position S.sub.5. The regulation algorithm for adjusting the discharge end position S.sub.1′ to the adjust position S.sub.2′ can, as stated, take place during a respective opening and/or closing gradient. The regulation process during a closing gradient is described below, that is, starting at time t.sub.2.

[0223] At time t.sub.2, that is, at the beginning of the discharge process, an electrical control voltage U is applied to the piezo actuator. The control voltage U is continuously increased, wherein a predominantly linear ratio between control voltage U and time t forms (upper part of FIG. 10; time t.sub.2 to t.sub.4). When the control voltage U is applied at time t.sub.2, the plunger is deflected again in the direction of the nozzle by the expanding piezo actuator. In the time period t.sub.2 to t.sub.3, a first, predominantly constant plunger speed is initially established (corresponds to m1′). Accordingly, a first (speed) ratio is formed between the change in the control voltage U of the piezo actuator and the plunger speed resulting therefrom.

[0224] At time t.sub.3, the plunger speed suddenly slows down, wherein a new plunger speed (corresponds to m4′) is established. In this case, the plunger speed approaches zero after t.sub.3. At time t.sub.3, an electrical voltage U.sub.3 is applied to the piezo actuator. However, since the control voltage of the piezo actuator continues to increase continuously even after time t.sub.3 or beyond U.sub.3, a new (speed) ratio is established between the change in the control voltage and the plunger speed. The time t.sub.3 or the plunger position S.sub.1′, S.sub.2′, S.sub.3 at which the change in the (speed) ratio takes place corresponds here to the full contact position S.sub.1′ of the plunger. Since this is an “ideal” and very rigid dosing system, the full contact position S.sub.1′ already corresponds to the discharge end position S.sub.3 and also the adjust position S.sub.2′ of the plunger.

[0225] The electrical control voltage U of the piezo actuator is further increased beyond U.sub.3 until the expansion voltage U.sub.1 is finally applied again to the piezo actuator at time t.sub.4.

[0226] An actual value of a value representing the sealing position actuator deflection can then be determined on the basis of the thus determined full contact position S.sub.1 and the electrical control voltage U.sub.3 of the piezo actuator associated with this position S.sub.1. In this case, the value that represents the sealing position actuator deflection corresponds to a voltage difference ΔU.sub.1 between the maximum electrical control voltage U.sub.1 applied to the piezo actuator during operation and the control voltage U.sub.3 that is necessary to bring the plunger into the full contact position S.sub.1. The sealing position actuator deflection ΔU.sub.1 determined in this way, that is, here the voltage difference ΔU.sub.1 of the control voltage applied to the piezo actuator, causes a sealing force of the plunger against the nozzle to build up from time t.sub.3. That is, the voltage difference ΔU.sub.1 is here essentially completely converted into a sealing force of the plunger. In contrast, the remaining portion of the control voltage applied to the piezo actuator, that is, the difference between U.sub.3 and U.sub.2, is converted into a movement of the plunger, wherein a (hydraulically) effective stroke H.sub.1 is effected here.

[0227] In FIG. 11, the procedure sub-step 9-G is shown for an “ideal” non-rigid dosing system. Analogous to FIG. 10, a function graph of the time profile of the electrical control voltage U applied to the piezo actuator (in V) over time t (in arbitrary units) is shown schematically in the upper part here, wherein the plunger position S (in μm) corresponding to the control voltage (U) is shown in the lower part for the same time period.

[0228] In FIG. 11, the determination of the sealing position actuator deflection is described on the basis of an opening gradient. An expansion voltage U.sub.1 is again applied to the piezo actuator at the beginning of the recording. The electrical control voltage is reduced at time t.sub.0′, wherein a pressure built up in the piezo actuator slowly starts to decrease as a result of the expansion. This means that during this time period (t.sub.0′ to t.sub.1′), initially only the sealing force that the plunger exerts against the nozzle is predominantly reduced. The electrical control voltage U is reduced from U.sub.1 to U.sub.3 in this time period (t.sub.0′ to t.sub.1′), wherein the difference between U.sub.1 and U.sub.3 here corresponds to the sealing position actuator deflection ΔU.sub.2.

[0229] In the time period t.sub.0′ to t.sub.1′, in addition to the reduction in the sealing force, there is also a slight plunger movement, wherein the plunger slowly moves from the discharge end position S.sub.3 or the adjust position S.sub.2′ into the full contact position S.sub.1′. This slight plunger movement corresponding to the slope m2′ is caused by an elastic (reversible) deformation of components of the dosing system. The continuously decreasing actuator pressure leads to the fact that the components compressed during a previous discharge process, for example, the fluidic unit, can “relax” or “reshape” and align again according to a non-compressed (target) arrangement. Correspondingly, the plunger can return from the discharge end position S.sub.3 to the full contact position S.sub.1′ during this time period, wherein the control voltage U of U.sub.1 and U.sub.3 is reduced.

[0230] The difference ΔU.sub.2 of these two voltage values U.sub.1, U.sub.3 (sealing position actuator deflection) can therefore also be used for the most part to build up sealing force in such a non-rigid dosing system, wherein a small proportion of the sealing position actuator deflection is converted into an elastic deformation of components of the dosing system (unlike in the completely rigid dosing system from FIG. 10).

[0231] In order to nevertheless achieve a certain sealing force, the spring stiffness of the overall system can be taken into account or compensated accordingly when calculating the adjust position S.sub.2′ (for example, according to equation 1). For this purpose, for example, the sealing position actuator deflection ΔU.sub.2 can be increased accordingly, wherein the (hydraulically) effective stroke H.sub.2 can in turn be reduced.

[0232] In the time period t.sub.1′ to t.sub.2′, the plunger position then changes faster than before, corresponding to a slope m1′. Due to the decreasing actuator voltage U and a spring system of the dosing system, the longitudinal extension of the piezo actuator is contracted, wherein the plunger is moved from the full contact position S.sub.1′ back to the discharge start position S.sub.5. The control voltage U of the piezo actuator is increased again at time t.sub.0′, wherein the plunger is deflected again in the direction of the nozzle and at time t.sub.4′, first the full contact position S.sub.1′, and, with a certain sealing force being built up and a slight movement of the plunger, the discharge end position S.sub.3 is finally reached at time t.sub.5′, which discharge end position corresponds to the adjust position S.sub.2′ of the plunger in the regulated state of the dosing system.

[0233] In FIG. 12, the procedure sub-step 9-G is now shown for clarification fora “real”, non-rigid dosing system on the basis of a closing gradient, wherein the basic structure of FIG. 12 corresponds to that of FIGS. 10 and 11 (time profile of the electrical control voltage U above; plunger position S corresponding to the control voltage U below). Starting from the discharge start position S.sub.5 of the plunger, a continuous increase in the electrical control voltage U applied to the piezo actuator results in the plunger being moved at a first speed (corresponds to m1′) in the direction of the nozzle (time period t.sub.4″ to t.sub.5″). The plunger speed slows down (corresponding to m3′) at time t.sub.5″, wherein the control voltage is further increased continuously. Correspondingly, at t.sub.5″, a new (speed) ratio is established between the change in the control voltage U of the piezo actuator and the plunger speed resulting therefrom. The reason for the slowing down of the plunger at time t.sub.5″ is an initial contact between the plunger and nozzle, wherein S.sub.4 corresponds to the initial contact position.

[0234] The plunger is deflected beyond S.sub.4 against a certain resistance of the nozzle further in the direction of the nozzle until the plunger has “slipped” completely into the nozzle at time t.sub.6″, thus achieving full contact (S.sub.1′). The slope m3′ thus represents the “sliding in” of the plunger into this nozzle, particularly into the full contact position S.sub.1′. An electrical control voltage ΔU.sub.4 is required to move the plunger from the discharge start position S.sub.5 to the full contact position S.sub.1, which electrical control voltage results from a difference between U.sub.3 and U.sub.2 (open-circuit voltage) of the piezo actuator.

[0235] The control voltage difference ΔU.sub.4 is part of the maximum control voltage U.sub.1 applied to the piezo actuator during operation, wherein ΔU.sub.4 is predominantly completely converted into the (hydraulically) effective stroke H.sub.3 of the plunger (and therefore essentially does not lead to the build-up of sealing force). The (hydraulically) effective stroke H.sub.3 here also corresponds to the plunger movement from the discharge start position S.sub.5 to the full contact position S.sub.1′.

[0236] At full contact (time t.sub.6′) the (speed) ratio changes again and the plunger is only moved very slightly (corresponding to m2′) to a discharge end position S.sub.3 (time t.sub.7″). As explained with reference to FIG. 11, the slope m2′ is caused by a slight elastic deformation of components of the dosing system. In addition, in the time period t.sub.6″ to t.sub.7″, a sealing force of the plunger is predominantly built up via the sealing position actuator deflection ΔU.sub.3.

[0237] On the basis of the actual sealing position actuator deflection determined in each case (actual value ΔU.sub.1, ΔU.sub.2, ΔU.sub.3, hereinafter only ΔU) it can then be determined in a step 9-VI. (FIG. 7c) via a comparison with a target value of the value representing the sealing position actuator deflection whether the current sealing position actuator deflection (here the voltage difference ΔU of the control voltage) is less than the target value. If the query shows that the target value is undershot, then according to step 9-VII., a temperature of the expansion material element increases, so that the target value of the sealing position actuator deflection (here a certain target voltage difference) is reached.

[0238] If the target value is not undershot (step 9-VI.), it is checked in step 9-VIII. whether the current sealing position actuator deflection (here the voltage difference ΔU of the control voltage) exceeds the target value. Optionally, then in step 9-IX., the temperature of the expansion material element is reduced in order to set the target value of the sealing position actuator deflection. If no deviation of the actual value (ΔU) of the sealing position actuator deflection from the target value is detected, a change is made directly to jump label C. without any regulation of the expansion material element. The query of the operating mode follows the jump label C. again (FIG. 7a; step 7-XIV.).

[0239] Finally, it is pointed out once again that the dosing systems or control methods for dosing systems described in detail above are merely embodiments which can be modified in the most varied of ways by the person skilled in the art without departing from the scope of the invention. Thus, for example, in the case of the control method explained, it is not always necessary to run through all the method steps, or the method steps could also be processed in a different order. Furthermore, the regulation algorithm can also be run through during the respective other “opening” or “closing” gradient not described in the context of the application. Furthermore, the use of the indefinite article “a” or “an” does not exclude the possibility that the relevant features can also be present more than once.

LIST OF REFERENCE SYMBOLS

[0240] 1 dosing system [0241] 10 actuator unit [0242] 11 housing [0243] 11a, 11 b housing block/components of the housing [0244] 12 actuator chamber [0245] 13 action chamber [0246] 14 movement mechanism [0247] 15 breakthrough [0248] 16 lever [0249] 17 lever contact surface [0250] 18 lever bearing [0251] 19 actuator spring [0252] 20 first actuator/piezo actuator [0253] 21 piezo stack [0254] 22 piezo actuator housing [0255] 23 pressure piece [0256] 30 second actuator/expansion material element [0257] 31 housing (expansion material element) [0258] 32 expansion body [0259] 33 heating device (expansion material element) [0260] 34 cooling region/cooling chamber (expansion material element) [0261] 35 piston [0262] 36 centering element [0263] 40 cooling device [0264] 41 coupling point for cooling medium supply [0265] 42, 42′, 42″ inflow channel (cooling medium) [0266] 43 proportional valve (expansion material element) [0267] 44 proportional valve (piezo actuator) [0268] 45 outflow channel (cooling medium) [0269] 46 coupling point for cooling medium discharge [0270] 50 fluidic unit [0271] 51 discharge element/plunger [0272] 52 plunger tip [0273] 53 plunger head [0274] 54 plunger contact surface [0275] 55 plunger spring [0276] 56 plunger centering piece [0277] 57 plunger bearing [0278] 58 plunger seal [0279] 60 nozzle [0280] 61 outlet opening [0281] 62 nozzle chamber [0282] 63 sealing seat [0283] 64 feed channel [0284] 65 reservoir interface [0285] 66 medium cartridge [0286] 67 cartridge holder [0287] 68 compressed air supply cartridge [0288] 69 connection cable [0289] 70 coupling mechanism [0290] 71 coupling spring [0291] 72 sphere [0292] 73 plug-in coupling part [0293] 74 spherical cap [0294] 75 heating (nozzle) [0295] 80 control unit (dosing system) [0296] 81 control unit connection cable [0297] 82 temperature sensor (medium) [0298] 83 temperature sensor (expansion material element) [0299] 84 Hall sensor [0300] 85 magnet [0301] 7 first procedure step [0302] 7-I. to 7-XIV. method steps (first procedure step) [0303] 7-i. iterative method step (first procedure step) [0304] 7-D, 7-E procedure sub-steps (first procedure step) [0305] 8 second procedure step [0306] 8-I. to 8-VI. method steps (second procedure step) [0307] 9 third procedure step [0308] 9-I. to 9-IX. method steps (third procedure step) [0309] 9-iii., 9-iv. iterative method steps (third procedure step) [0310] 9-G procedure sub-step (third procedure step) [0311] a distance (plunger tip: nozzle) [0312] m1, m2 ratio (plunger position:temperature) [0313] m1′, m2′, m3′, m4′ ratio (plunger position:time) [0314] K tilt axis [0315] H.sub.1, H.sub.2, H.sub.3 (hydraulic) effective stroke [0316] R discharge direction [0317] RS, RS' movement direction of the plunger [0318] S.sub.1, S.sub.1′, S.sub.2, S.sub.2′, S.sub.3, S.sub.4, S.sub.5 plunger position [0319] t.sub.0-t.sub.4 points in time [0320] t.sub.0′-t.sub.5′ points in time [0321] t.sub.0″-t.sub.7″ points in time [0322] T.sub.1, T.sub.2 temperature (expansion material element) [0323] U.sub.1, U.sub.2, U.sub.3 voltage (piezo actuator) [0324] ΔU.sub.1 ΔU.sub.1, ΔU.sub.2, ΔU.sub.3, ΔU.sub.4 voltage difference/actual value