ACTUATOR MODULE HAVING SEALED ENCLOSURE - Patent application

Abstract

The present invention relates to an actuator module (1) having a sealed housing (3) with at least one piezo actuator (2) disposed therein and electrical terminals (21, 22) for at least the piezo actuator (2). The terminals (21, 22) pass through housing walls (31, 32, 34), and an interior housing space (30) between the piezo actuator (2) and the housing walls (31, 32, 34) contains a potting compound (4) that electrically insulates the housing walls (31, 32, 34) from the piezo actuator (2). The potting compound (4) is solid and contains at least one particulate, thermally conductive, insulating auxiliary material (40), which is arranged within the potting compound (4) such that heat dissipation from the piezoelectric actuator (2) to the housing wall (31, 32, 34) occurs via the potting compound (4), and in particular via the auxiliary material (40), during operation.

Description

[Technical field]

[0001] The present invention relates to an actuator module having a sealed housing, the actuator module having at least one piezoelectric actuator arranged in the housing and at least electrical terminals for the piezoelectric actuator, a weighing system having such an actuator module, a method for manufacturing such an actuator module, the use of such an actuator module in a weighing system, and the sealed housing. [Background technology]

[0002] Piezoceramic multilayer actuators, or piezo actuators, are generally composed of a number of stacks of thin layers of piezoelectric material, for example lead zirconate titanate. In the case of such multilayer piezo actuators (also called "multilayer elements" or "piezo stacks"), several thin piezo elements are cascaded together with internal electric poles located between them. These internal electric poles are alternately routed to the surface of the piezo actuator, where two outer electric poles connect the respective internal electric poles. These internal electric poles are electrically connected in parallel and are combined to form two groups that form the connecting poles of the piezo actuator. When a voltage is applied to the connecting poles, it is transferred in parallel to the internal electric poles, and through them an electric field is generated in the layers of piezoelectric material. The sum of the mechanical deformations of the individual layers of piezoelectric material results in the available extension and / or force of the piezo actuator.

[0003] Piezo actuators are used in various technical fields, for example in actuation and positioning drives or in metering systems for the systematic metering of liquids to viscous metering substances, in particular in so-called jet valves. Significant advantages of piezo actuators are, for example, that they have high stiffness and compressive strength, provide high position resolution, exhibit rapid response behavior, provide high acceleration and generally operate without wear.

[0004] Despite these advantages, the reliability of piezo actuators has often been inadequate in the past. Due to the high electric field strength applied to the surface of a piezo actuator during operation, polar molecules, e.g., water molecules, are attracted from the air surrounding the actuator. The accumulation of water molecules leads to an increase in the electrical conductivity on the surface of the piezo actuator and an increase in leakage current. As a result, short circuits can occur in the layer of piezoelectric material, which has a detrimental effect on the lifespan of the piezo actuator.

[0005] Piezo actuators are known in which the piezoelectric material is coated, for example by a ceramic coating or with glass, but microcracks often occur during operation of the piezo actuator, in which case water molecules can pass through the coating. In the case of such piezo actuators, there is often the problem that a small amount of water molecules present in the housing, for example as a result of manufacture, can already be sufficient to induce the above-mentioned detrimental effects.

[0006] There are also piezo actuators tightly enclosed in a metallic housing, in which, for example, a water-absorbing medium, e.g., a medium that chemically converts and / or binds water molecules, may be disposed. A disadvantage of such piezo actuators may be that their manufacture is relatively complex due to the complex manufacturing methods and chemicals used.

[0007] A further disadvantage of a piezo actuator tightly enclosed in a metal housing - with or without an absorbing medium - may result from the fact that heat dissipation from the surface of the piezo actuator is limited during operation due to the metal housing and / or the (absorbing) medium in the housing. The temperature of the piezo actuator may affect the geometry of the piezo actuator, in particular its longitudinal extension in the (switched off) rest state.

[0008] As a result of thermally induced elongation, the longitudinal elongation of the piezo actuator and / or the generated forces and / or the position of the piezo actuator inside the machine may deviate from certain target values, especially due to insufficient heat dissipation from the piezo actuator during operation. Due to the fact that a certain high precision is required during the operation of the piezo actuator in many applications, temperature induced changes in the length of the piezo actuator should be avoided if possible.

[0009] Known piezo actuators using tightly sealed metallic housings and / or specific media therein, e.g., water-absorbing media, can therefore only be used to a limited extent in many technical fields. In particular in the case of the above-mentioned jet valves, which currently typically operate at high clock frequencies of up to 1 kHz, in which case correspondingly large heat losses occur in the piezo actuator, an actuator module is desirable that provides sufficient heat dissipation from the surface of the piezo actuator for reliable operation and at the same time provides effective protection of the piezo actuator against damaging environmental conditions. Summary of the Invention [Problem to be solved by the invention]

[0010] It is an object of the present invention to provide an actuator module with a sealed housing, a weighing system with such an actuator module, a method for manufacturing an actuator module, and a housing, in which the above-mentioned disadvantages can be avoided or at least reduced. [Means for solving the problem]

[0011] This object is solved by an actuator module according to claim 1 and a manufacturing method according to claim 7, a weighing system according to claim 14 and a housing according to claim 15, and a use of the actuator module according to claim 16.

[0012] The actuator module according to the invention has a tightly sealed, in particular substantially tightly sealed, housing. At least one piezo actuator is arranged inside the housing. The piezo actuator can in particular be a piezo ceramic multilayer actuator. The actuator module has at least two electrical terminals for at least the piezo actuator. These electrical terminals pass through the housing wall of the housing in a particularly tightly sealed and electrically insulating manner.

[0013] In the context of the present invention, the term "sealed" is understood as meaning that the housing is formed in such a way that no substance can pass through it or that no substance can pass through the sealed housing. The housing is "sealed" in such a way that no solid and / or any liquid and / or any gas can enter the housing from the outside during operation of the actuator module. The housing preferably forms a "perfectly tight" containment or enclosure of the piezo actuator with respect to the housing's environment. A "perfectly tight" housing is understood in such a way that the exchange of, in particular, air and / or water molecules is prevented by the housing. The housing can thus be "absolutely tight" at least (relatively) with respect to air and / or water molecules for a certain operating time, in particular to prevent the long-term diffusion of water molecules through the material of the housing during operation. The hermeticity of the housing can be analyzed, for example, via a helium leak test. The housing can in particular be a deep-drawn housing, as described later.

[0014] According to the invention, with respect to the piezoelectric actuator, a potting compound is disposed in the housing interior space inside the housing between the piezoelectric actuator and the housing wall, which potting compound electrically insulates the housing wall, particularly during operation of the piezoelectric actuator.

[0015] The potting compound is a solid, in particular an elastic solid, and contains at least one particulate, thermally conductive, insulating auxiliary material. In particular, the auxiliary material itself is an insulator. The auxiliary material is formed in particulate form, i.e., the auxiliary material is present as a solid in the potting compound. The auxiliary material can also be called a functional material.

[0016] According to the invention, the auxiliary material is arranged in the potting compound in the housing such that heat dissipation from the piezo actuator to the housing wall occurs via the potting compound, in particular via the auxiliary material in the potting compound, during operation of the actuator module. The auxiliary material is preferably arranged in the potting compound such that heat dissipation from the surface of the piezo actuator occurs substantially evenly along the entire longitudinal extension of the piezo actuator, in particular laterally, during operation of the actuator module. The heat dissipated from the piezo actuator can preferably be mainly conducted to the housing jacket of the housing wall, as described later. The heat dissipated from the piezo actuator can in particular be loss heat generated during operation of the piezo actuator.

[0017] The reliability of the piezo actuator can be advantageously increased by the actuator module according to the invention, since the said piezo actuator is effectively protected against damaging environmental influences, in particular against (air) moisture, via the above-mentioned sealed housing. A particularly efficient heat dissipation from the piezo actuator according to the invention can furthermore take place by combining a solid elastic potting compound with a thermally conductive, insulating auxiliary material arranged therein, in which case the piezo actuator can be reliably protected against overheating. On the one hand, this can have an advantageous effect on the service life of the piezo actuator itself, so that the latter or the actuator module, respectively, must be replaced less frequently. On the other hand, since thermally induced extension of the piezoelectric actuator is largely prevented, particularly high weighing accuracy can be achieved by the actuator module in the case of a weighing system, in which case the efficiency of the weighing system can also be increased, since the piezoelectric actuator is protected against overheating even during continuous operation, so that disturbances of the weighing operation due to critical temperatures of the piezoelectric actuator can be avoided.

[0018] The actuator module according to the invention is furthermore advantageously suitable for applications where particularly high clock frequencies of the piezo actuator are required, since particularly efficient dissipation of heat loss from the piezo actuator surface to the housing wall and, via this, output of said heat to the environment is possible via the potting compound and the added auxiliary substances. The actuator module can therefore advantageously be used in jet valves with very high clock frequencies, for example up to 2 kHz, which corresponds to at least double the clock frequency compared to conventional jet valves and is not easily possible with known actuator modules. The actuator module can also be successfully operated in jet valves operating at clock frequencies of 3 kHz or 4 kHz.

[0019] A method according to the invention for manufacturing an actuator module, preferably having a sealed housing and at least one piezo actuator arranged in said housing, comprises at least the following steps:

[0020] In one step, a sealable housing is provided, in which case the housing has electrical terminals for at least one piezo actuator. In the sealed state of the housing, these terminals penetrate in particular the housing wall of the housing in a tightly sealed and electrically insulating manner. Providing the housing can include a feed-through of the electrical terminals through the housing wall. However, it is also possible for housings with penetrated electrical terminals to be attached in the method. The housing can in particular be a deep-drawn housing.

[0021] In a further step, at least one piezo actuator is introduced into the housing interior space inside the housing. Prior to introducing the piezo actuator into the housing, the electrical terminals of the housing are preferably brought into contact with assigned connection points or connection poles of the piezo actuator. For example, the electrical terminals can pass through the housing cover, in which case they are connected to the connection poles of the piezo actuator and / or the piezo actuator is fixed to the housing cover prior to introducing the piezo actuator into the housing interior space.

[0022] In an optional step, at least a part of the piezo actuator, in particular at least a part of the surface of the piezo actuator, can be cleaned by plasma. Substantially the entire surface of the piezo actuator facing the housing wall can preferably be cleaned by plasma cleaning. The (outer) surface of the piezo ceramic material of the piezo actuator and / or the connection poles of the piezo actuator, in particular the surface of the piezo actuator between these connection poles, can preferably be cleaned by plasma.

[0023] Alternatively or additionally, at least a part of the inner surface of the housing wall can be selectively cleaned by plasma. The inner surface of the housing wall is the area of ​​the housing wall facing the housing interior space, in particular the piezo actuator in the housing. The (inner) housing wall facing the housing interior space can therefore be cleaned by plasma cleaning at least in a plurality of parts. Substantially the entire housing wall directed towards the housing interior space, in particular substantially the entire inner surface of the housing wall, can preferably be cleaned by plasma.

[0024] In a further step a potting compound is provided which, preferably in a cured state, electrically insulates the housing walls from the piezo actuator.

[0025] In a further step, a potting compound, preferably free-flowing, is introduced into the housing interior space between the piezoelectric actuator and the housing wall. The potting compound is preferably introducible into the housing interior space via a filling opening in the housing, in particular in the housing cover.

[0026] In particular, after curing or solidification in the housing interior space, the potting compound is solid, preferably elastic solid, and comprises at least one particulate, thermally conductive, insulating auxiliary substance, which is arranged in the potting compound such that heat dissipation from the piezoelectric actuator, in particular from the piezoelectric actuator face to the housing wall, during operation of the actuator module, occurs via the potting compound, in particular via the auxiliary substance in the potting compound.

[0027] In a further step, the housing is sealed to form the actuator module. To this end, the filling opening can be blocked by pushing in a pressure ball, which preferably has a larger diameter than the filling opening.

[0028] It should be pointed out that the method steps do not necessarily have to be performed in the order mentioned above: it is also possible that the two method steps are combined into one step or are performed substantially simultaneously.

[0029] Advantageously, actuator modules that are particularly suitable for use in metering systems, such as jet valves, can be produced by the method. Such actuator modules for metering systems often have to meet particularly stringent quality requirements, in particular with regard to the shielding of the piezo actuator against moisture during operation and the temperature of the piezo actuator, which can be met by the production method according to the invention and the actuator module obtained thereby.

[0030] A metering system according to the invention for a metered substance comprises a nozzle for outputting the metered substance, a supply channel for the metered substance to said nozzle, a preferably movably mounted discharge element, an actuator module according to the invention connected to said discharge element and / or said nozzle and having a sealed housing and at least one piezo actuator arranged in said housing. The metering system may comprise further components as described later.

[0031] The actuator module according to the invention can advantageously be used successfully in metering systems, as mentioned above, in particular in jet valves, the clock frequency for the output of the metered substance being able to be significantly increased in particular by using the actuator module, compared to known metering systems with encapsulated conventional piezo actuators.

[0032] The invention further relates to a tightly sealed housing with at least one component arranged therein, preferably a piezo actuator. The housing comprises at least two electrical terminals for a component, in particular for controlling the piezo actuator. The terminals pass through the housing wall of the housing, in particular in a tightly sealed and electrically insulating manner. The housing has an integrally formed housing base body and a housing cover connected thereto, in particular in a tightly sealed manner.

[0033] According to the invention, the housing base body can be obtained by deep drawing, in particular by deep drawing of plain sheet metal. This means that the housing base body is a deep-drawn part. The housing base body comprises an integrally or integrally formed, preferably tubular housing jacket and a housing bottom, where the housing bottom closes or defines the housing jacket on one (end) side. Depending on the design of the housing and / or the arrangement of the components, for example the piezo actuators, the housing bottom can also generally be called a housing cover. The housing base body according to the invention is therefore defined in that it comprises at least one housing jacket with which it is integrally formed and a one-sided limiting part of the housing jacket which is firmly connected thereto, for example in the same way as a deep-drawn pot. Without being limited thereto, in the present description it is assumed that the housing base body comprises a housing jacket and a housing bottom which is integrally connected thereto.

[0034] In the case of the present housing, advantageously, the mass of the housing bottom produced by deep drawing can be significantly reduced compared to conventional housings with a separate housing bottom that is subsequently welded to the housing jacket, for example. Due to the fact that the housing bottom, which can be actively moved by a piezo actuator, has a relatively small mass, the effective stroke of the piezo actuator can be significantly increased compared to conventional encapsulated piezo actuators. Due to the fact that in the case of the present housing, only one element is furthermore to be connected to the housing base body, for example the housing cover, the manufacture of the present housing is relatively uncomplicated in terms of the tightness to be achieved.

[0035] Due to the small displaced mass of the housing bottom, the housing is also suitable for metering systems, in particular jet valves, with particularly high clock frequencies. Deep-drawn housings can therefore be particularly preferably used as part of an actuator module according to the invention, since the advantageous effects of the housing are thus synergistically complemented by the advantages of this particular actuator module, particularly in the case of high clock frequencies.

[0036] The present invention further relates to the use of an actuator module having a sealed housing and at least one piezo actuator arranged in the housing, in particular the use of an actuator module according to the present invention, in a metering system having at least one supply channel for a metered substance, a nozzle for outputting the metered substance and a preferably movably mounted discharge element, in which the actuator module cooperates with or is connected to the discharge element and / or the nozzle during operation, respectively, to output the metered substance.

[0037] Furthermore, particularly advantageous designs and further developments of the present invention are of course subject to the dependent claims which follow, in which case dependent claims of one claim category can also be further developed analogously with dependent claims and exemplary embodiments of a different claim category, and individual features of different exemplary embodiments or variants can also be combined to form new exemplary embodiments or variants, respectively.

[0038] The housing is formed in such a way that the entire piezo actuator is completely disposed in the housing. The piezo actuator is in particular enclosed in the housing in a tight-sealing manner. The housing thus differs from known enclosures, such as for example metal sleeves, which are simply pressed onto the piezo actuators, in which case areas of the individual piezo actuators, such as for example the actuator feet, then protrude from the sleeve. Such a sleeve is therefore not a "sealed" housing in the sense of the present invention. It is also generally possible that two or more piezo actuators are enclosed in the same housing in a tight-sealing manner. For example, two separately controllable piezo actuators can be disposed substantially parallel to each other in the same housing, in which case the housing interior space between the respective piezo actuator and the housing wall and / or between these two piezo actuators can then contain a potting compound. Without being limited thereto, unless otherwise stated, the present invention is described below on the basis of a housing with only one piezo actuator.

[0039] As mentioned above, the housing can be a deep-drawn housing. It should also be pointed out that in all embodiments or in each case of further developments of the invention, a housing obtained by deep drawing can be used. This means that as part of this description it will be specifically understood that "housing" is a deep-drawn housing.

[0040] The housing comprises a potting compound preferably introduced into the housing in a free-flowing form to solidify or harden in the housing. The potting compound can in particular be poured and / or injected into the housing. The potting compound can also be called a casting compound. The potting compound is preferably provided in the housing by introducing a free-flowing potting compound into the interior of the housing. The potting compound in the housing, in particular during operation of the actuator module, preferably forms a flexible solid object in a hardened state.

[0041] The potting compound in the housing comprises at least one thermally conductive auxiliary material. The intrinsic thermal conductivity of the auxiliary material, i.e. the thermal conductivity of the auxiliary material itself, can preferably be at least about 2.5 W / (m·K), preferably at least about 30 W / (m·K), preferably at least about 50 W / (m·K), more preferably at least about 100 W / (m·K), more preferably at least about 200 W / (m·K), particularly preferably at least about 300 W / (m·K), in particular at least about 400 W / (m·K). The above-mentioned values ​​can be referred to as the thermal conductivity of the auxiliary material, which is preferably present in the form of a solid block, for example in the form of a massive auxiliary material block. As usual, the thermal conductivity or thermal conductivity coefficient is understood to be a material property of the auxiliary material that determines the flow of heat through the material or auxiliary material by thermal conduction.

[0042] The thermally conductive insulating auxiliary material preferably comprises a plurality of individual auxiliary material particles or a plurality of auxiliary material particles, in particular before being introduced into the potting compound. The auxiliary material particles can also be generally agglomerated to form several particles, and can selectively form a coherent structure. However, each auxiliary material particle is preferably formed separately, in particular before being introduced into the potting compound. Without being limited thereto, in the description of the present invention, it is assumed that the auxiliary material used comprises a plurality of auxiliary material particles, in which case at least the majority of the auxiliary material particles are formed separately, i.e., the auxiliary material particles are preferably present in an isolated form. The auxiliary material can preferably have a substantially powdery form, in particular before being introduced into the potting compound.

[0043] In particular, the powdered auxiliary material outside the potting compound may preferably have an (intrinsic) thermal conductivity of at least about 1 W / (m·K), preferably at least about 2 W / (m·K), preferably at least about 3 W / (m·K), more preferably at least about 4 W / (m·K), more preferably at least about 5 W / (m·K).

[0044] The auxiliary material can preferably be formed in the form of a platelet, also called auxiliary material platelet. The auxiliary material in the potting compound can preferably be present in the form of a platelet in the housing. Each auxiliary material particle in the housing can have, in particular, a predominantly platelet-like design. The auxiliary material can preferably be an "anisotropic" filler and / or a filler with a large aspect ratio. The aspect ratio of the auxiliary material particle can be, for example, at least about 5:1, preferably at least about 25:1, preferably at least about 40:1.

[0045] A "platelet" is understood to be a flat element or particle having substantially the same thickness everywhere and delimited on two opposite sides by respective mainly flat surfaces (base surfaces) that are relatively broadened compared to the thickness. It should be pointed out that each auxiliary material particle can also be designed approximately only as a "platelet". Such auxiliary material particles having slightly different thicknesses within the same particle are therefore also called "platelets". A "platelet-like" auxiliary material particle is also called an auxiliary material platelet and is therefore defined in particular in that it has two mainly flat base surfaces, in which case the thickness of the auxiliary material particle (corresponding to the distance between the base surfaces) is several times smaller compared to the broadening of the base surfaces.

[0046] The auxiliary material can be at least partially arranged in the potting compound, in particular substantially all of the auxiliary material particles, so that the longitudinal extension of each platelet or auxiliary material platelet extends transversely, preferably substantially perpendicular to the longitudinal extension of the piezo actuator in the housing. The auxiliary material particles, in particular substantially all of the auxiliary material particles, can preferably be arranged in the potting compound such that the longitudinal extension of each auxiliary material platelet corresponds to the shortest distance between the surface of the piezo actuator and the housing wall, in particular a defined heat output area of ​​the housing.

[0047] The longitudinal extension (longitudinal extent) of a piezo actuator is understood to be the maximum or longest extension (extension) of the piezo actuator in one direction. The longitudinal extension (longitudinal extent) of an auxiliary material platelet is understood to be the maximum or longest extension (extension) of the auxiliary material platelet in one direction, in particular along at least one base surface of the auxiliary material platelet.

[0048] Particularly efficient heat dissipation during operation can advantageously occur due to the specific arrangement of the auxiliary material platelets in the potting compound with respect to the piezo actuator. In the case of piezo actuators, due to the layered structure, heat dissipation occurs mainly laterally or radially during operation. This means that the lost heat is mainly output from the piezo actuator face towards the sides with respect to the longitudinal extension of the piezo actuator, in which case heat is hardly output in the axial direction, for example in the direction of the actuator foot or head. In the case of encapsulated piezo actuators, it is therefore particularly effective when at least a large part of the lost heat can be transferred laterally or radially away from the piezo actuator via the auxiliary material platelets in the potting compound. In particular, because the lateral regions of the piezo actuator occupy a relatively large part of the total surface of the piezo actuator.

[0049] The auxiliary material particles can be advantageously arranged in the potting compound, in particular in the immediate vicinity of the surface (piezo actuator face) of the piezo actuator and / or the housing wall, so that the longitudinal extension of the individual auxiliary material platelets corresponds substantially to the (main) heat output direction of the adjacent piezo actuator during operation. The auxiliary material platelets can preferably be aligned in one direction in the potting compound and arranged so as to be substantially evenly distributed along the longitudinal extension of the piezo actuator. The occurring loss heat can be dissipated particularly effectively in the direction from the piezo actuator face to the housing wall due to the thermally conductive auxiliary materials and their alignment in the potting compound. In contrast, in the case of known compounds with embedded auxiliary materials, the auxiliary material particles often cannot be arranged in a specific direction for technical reasons, which can have a detrimental effect on the thermal properties of the component.

[0050] Furthermore, advantageously, a particularly effective "thermal conduction path" can also be formed in the potting compound, in particular in the (entire) area between the piezo actuator face and the housing wall, in particular between the piezo actuator face and the housing jacket. In this description, that part of the preferably deep-drawn housing which extends at least along the longitudinal extension of the piezo actuator, in particular that part which extends along the piezoelectric material of the piezo actuator, is understood to be the housing jacket.

[0051] It can be advantageously achieved through the properties of the auxiliary material (platelet-shaped design) in combination with the alignment of the individual auxiliary material particles in the potting compound (mainly perpendicular to the longitudinal extension of the piezo actuator) that the individual auxiliary material particles in the potting compound are in active contact with at least one other auxiliary material platelet, if possible, via at least one contact point in each case. Two auxiliary material particles can preferably be in direct contact at the contact point.

[0052] The auxiliary material platelets can be arranged in the potting compound in particular such that a preferably uninterrupted connection or "bridge" between two or more auxiliary material particles is formed via the respective contact points. Such bridges of auxiliary material particles can be preferably formed in each case such that a heat conduction path of the loss heat between the piezo actuator surface and the housing wall, in particular the housing jacket, is formed therethrough, preferably uninterrupted. Particularly preferably, the auxiliary material platelets can be arranged in the potting compound in such a way that a plurality of such bridges of auxiliary material particles ("auxiliary material particle bridges") are preferably arranged mainly parallel in the potting compound. The bridges of auxiliary material particles can be preferably arranged in the potting compound in such a way that they are substantially evenly distributed along the longitudinal extension of the piezo actuator.

[0053] Heat dissipation from the piezo actuator can advantageously be further improved via such a heat conduction path. Due to the fact that, with respect to their longitudinal extension, preferably substantially all of the auxiliary material platelets are arranged in the potting compound mainly perpendicular to the longitudinal direction of the piezo actuator, heat can be systematically transferred from the piezo actuator to the housing jacket of the housing wall, in which case undesirable, for example, axial heat conduction in the potting compound can be prevented as far as possible. Due to the alignment of the auxiliary material platelets, it is further possible that the lost heat can be further transferred to the housing jacket on the most direct or shortest possible path via the formation of bridges.

[0054] It is further advantageous compared to the same mass of auxiliary material, in particular isotropic, e.g. spherical, that a relatively large number of contact points can be formed between the auxiliary material particles (present in the potting compound) via the platelet-like designed auxiliary material particles and their alignment in the potting compound. Due to the fact that the lack of (direct) contact between the auxiliary material particles can have a detrimental effect on the effectiveness of the heat conduction path, e.g. due to the potting compound not conducting heat well, the amount of heat dissipated (per unit time) from the piezo actuator during operation can be further increased by the design of the auxiliary material particles and their orientation in the potting compound.

[0055] The auxiliary material can preferably be boron nitride (BN). Particularly preferably, the auxiliary material can be hexagonal boron nitride (α-boron nitride). Hexagonal boron nitride (α-BN, hexagonal) is well known and consists of flat, hexagonal honeycomb-structured layers in which B-atoms and N-atoms in each case alternate. Particularly preferably, boron nitride can be present as auxiliary material before processing in the form of a powder with a well-defined crystal structure. Before the above-mentioned processing and / or in the hardened potting compound, boron nitride can be present in particular in the form of platelet-like monocrystals. Particularly preferably, the respective (BN) monocrystals can form in each case an auxiliary material particle or in each case an auxiliary material platelet.

[0056] The average size of the platelets or auxiliary material platelets, respectively, in particular the average diameter of the BN single crystals in the potting compound, can be at least about 10 μm, preferably at least about 20 μm, preferably at least about 30 μm and / or at most about 100 μm, preferably at most about 80 μm, preferably at most about 60 μm, in particular about 45 μm. The size or diameter of the auxiliary material platelet is generally understood to be the longest extension of the auxiliary material platelet in one direction, in particular if the auxiliary material platelet has an irregular outer contour. The average particle size (D 50 ) can preferably be about 45 μm. For example, the auxiliary material boron nitride can be of the type "CL-SP045" (manufacturer: Henze Boron Nitride Products, AG, Germany).

[0057] Due to the particularly high thermal conductivity of boron nitride (e.g. up to about 5 W(m·K) in the case of powdered BN), heat dissipation from the piezo actuator surface can advantageously be further increased. Further advantages of boron nitride compared to other thermally conductive substances are the low dielectric constant as well as the high insulation resistance, so that boron nitride is particularly suitable in combination with encapsulated piezo actuators. α-modified boron nitride has a low density (about 2.25 g cm) compared to other thermally conductive substances. -3 Due to the fact that the boron nitride has a mass percentage of 0.01 mass % (0.01 mass %), the mass percentage of boron nitride in the potting compound can be reduced compared to other thermally conductive substances, in which case a certain flow of heat can nevertheless be achieved. The weight of the actuator module can therefore be reduced, if necessary. The above-mentioned heat flow is understood as the thermal energy dissipated per unit time from the piezo actuator surface through the entire potting compound, i.e. the heat capacity.

[0058] Heat dissipation from the piezo actuator can furthermore advantageously be increased by the specific shape and size of the individual BN auxiliary material particles, because the number of contact points required between the individual auxiliary material particles to form a heat conduction path can be reduced with an increase in particle size, in which case each contact point forms a thermal resistance. In the case of BN auxiliary material particles of a specific size, a particularly efficient heat dissipation is therefore possible, in which case the BN auxiliary material particles can nevertheless be arranged in the potting compound in a desired manner. A further advantage follows from the fact that hexagonal boron nitride has the properties of a dry lubricant, in which case the coefficient of friction at the standard (surface) temperature of the piezo actuator remains stable. The piezo actuator can therefore be stored in a sliding manner via the boron nitride in the potting compound.

[0059] The auxiliary material, in particular hexagonal boron nitride, can preferably comprise a mixture of (auxiliary material) particles, preferably platelets, having at least two different average sizes. The auxiliary material can in particular comprise a mixture of powdered boron nitride having a first average particle size and powdered boron nitride having a second average particle size different therefrom. An auxiliary material provided in the form of a mixture or the like is also called an auxiliary material mixture.

[0060] The mixture can be preferably provided in such a way that a boron nitride powder having a (relatively) small average particle size is mixed with a boron nitride powder having a (relatively) large average particle size. The auxiliary material preferably has an average particle size (D 50 ) and an average particle size (D 50 ) can be used in the above mixture. Boron nitride of the type "CL-SP045" and "CL-ADM20" can be preferably used in the above mixture (manufacturer: Henze Boron Nitride Products, AG, Germany). Powdered boron nitride with an average particle size of about 20 μm, for example type "CL-ADM20", preferably has an approximately platelet-like design.

[0061] Powdered boron nitride having an average particle size of about 20 μm can be mixed with powdered boron nitride having an average particle size of about 45 μm, such that the (mixed) portion is at least about 1 weight percent relative to the total amount of the (premixed) auxiliary material or auxiliary material mixture. Preferably, the (mixed) portion is at least about 2 weight percent, preferably at least about 3 weight percent, particularly preferably at least about 4 weight percent. Preferably, the (mixed) portion is at least about 4.25 weight percent, particularly preferably at least about 4.5 weight percent.

[0062] By using boron nitride containing powders with different average particle sizes, heat dissipation from the piezo actuator can advantageously be further increased, for example (relatively) small boron nitride particles can enter into intermediate spaces between (relatively) large boron nitride particles and at least partially fill them and / or extend the contact surface of the boron nitride with the housing.

[0063] In addition to the auxiliary material, the potting compound in the housing preferably comprises a silicone gel, which comprises at least one base silicone and at least one crosslinking agent, in particular a curing agent.Alternatively or in addition to the silicone gel, the potting compound in the housing can also comprise one or several polyurethanes.The potting compound can also generally be formed from other base components.

[0064] The potting compound in the housing is preferably formed to have at least one, and preferably all (simultaneously) of the following characteristics during operation of the actuator module during a particular period of use of the actuator module: Virtually no separation of low molecular weight reaction products, e.g., H2O, NH3, CO2, acetic acid, etc., from the potting compound occurs during operation. The insulation resistance of the base component of the potting compound (without auxiliary substances), e.g. silicone gel, is preferably at least 1×10 12 Ω cm, preferably at least 1×10 15 Ω cm, specifically at least 1×10 16 Ω·cm or more. The (maximum) use temperature of the potting compound is at least 140°C, preferably at least 160°C, more preferably at least 200°C or higher. For a certain period of use, the potting compound is stable to ageing processes, in particular by preventing the separation of conductive reaction products. Preferably, the thermal conductivity of the base component of the potting compound (without auxiliary substances), e.g. a silicone gel, is at least 0.08 W / (m·K), preferably at least 0.15 W / (m·K), in particular at least 0.2 W / (m·K).

[0065] Preferably, the potting compound in the housing, especially the silicone gel (cured), has an average hardness (Shore A) of at least about 25, preferably at least about 35, preferably at least about 55 and / or an average hardness of at most about 75, preferably at most about 65.

[0066] The potting compound in the housing is advantageously formed as a (rigid) solid so that a certain alignment of the auxiliary material particles in the potting compound is maintained during the operation of the actuator module. However, the potting compound in the housing is also formed flexible to provide an extensional movement of the piezo actuator during operation and / or to provide a (slight) deformation of the housing during operation. A further advantage of the potting compound with at least one silicone gel results during the manufacture of the actuator module, in that the potting compound can be introduced in a free-flowing form into the housing through a small filling opening, and then solidifies into a flexible solid at the housing at the end, as described later.

[0067] The potting compound can preferably be such that the portion of the potting compound in the housing, particularly the auxiliary material, particularly the hexagonal boron nitride, or the auxiliary material mixture, respectively, in particular the cured potting compound, is at least about 50 weight percent, preferably at least about 60 weight percent, preferably at least about 65 weight percent, in particular at least about 70 weight percent.

[0068] The heat dissipation from the piezo actuator can advantageously be further improved by such a high mass percentage of hexagonal boron nitride in the potting compound: in the case of a mass percentage of α-boron nitride of 50 weight percent or more, it is particularly achievable that the thermal conductivity of the potting compound in the housing approaches that of the piezo actuator in the lateral direction, i.e. by including boron nitride, in which case the thermal conductivity of the potting compound can also substantially correspond to that of the piezo actuator in the lateral direction.

[0069] The auxiliary material, in particular boron nitride, can therefore be arranged in the potting compound such that the thermal conductivity of the hardened potting component in the housing is at least about 90%, preferably at least about 95%, preferably at least about 99%, particularly preferably about 100%, in particular about 101% or more of the thermal conductivity of the piezo actuator, in particular in the lateral direction or in the direction of the shortest path to the housing wall. The lateral direction is understood to be a direction substantially transverse to the longitudinal extension of the piezo actuator. For example, the lateral direction can extend approximately parallel to the internal electrodes of the piezo actuator. The lateral region of the piezo actuator can preferably be in the region of the piezo actuator between the actuator foot and the actuator head, in particular in the part with the inner electrodes stacked in layers.

[0070] For example, the thermal conductivity of the piezo actuator surface in the lateral direction during operation of the actuator module, i.e. during operation of the piezo actuator, can be about 2.45 (W / (m·K)). A potting compound can then be formed, preferably with respect to the nature of the boron nitride and / or the mass percentage of boron nitride and / or the alignment of the BN single crystals in the potting component, so that the thermal conductivity of the final potting compound, particularly in the lateral direction, from the piezo actuator surface to the housing wall or housing jacket, respectively, is at least about 2.45 (W / (m·K)) or slightly greater than 2.45 (W / (m·K)). A further increase in the thermal conductivity of the final potting compound, particularly in the lateral direction, can advantageously be achieved by a mixture of boron nitride powders with different average particle sizes. For example, in the case of a mixture of about 1.5 weight percent boron nitride having an average particle size of 20 μm and about 98.5 weight percent boron nitride having an average particle size of 45 μm, a final potting compound thermal conductivity of greater than 3.5 (W / (m·K)) is achievable. The final potting compound thermal conductivity can even be 4 (W / (m·K)) or greater.

[0071] The heat losses occurring during the operation of the actuator module can therefore advantageously be completely dissipated mainly from the piezo actuator surface, so that the piezo actuator can be kept within a certain temperature range. This can be particularly advantageous in the case of jet valves with high clock frequencies, since the risk of overheating of the piezo actuator is prevented and thus continuous operation is possible.

[0072] For particularly efficient heat dissipation, the housing interior space between the piezo actuator and the housing wall can be substantially completely filled with the hardened potting compound during operation. "Substantially completely" should be understood in such a way that a certain expansion volume can be present in the housing, in particular to compensate for the (necessary) thermal expansion of the piezo actuator and / or the potting compound. Such an expansion area free of potting compound can, for example, contain a volume of inert gas and / or be formed as an elongated hollow space running substantially parallel to the longitudinal extension of the housing.

[0073] The housing that hermetically encloses the piezo actuator is preferably formed to be "permanently resistant to vibrations". "Permanently resistant to vibrations" or "durable" is understood here as meaning that the housing itself does not show signs of fatigue as a part of the typical life of the piezo actuator itself arranged in the housing, i.e. after a large number of vibrations (deflections) that the piezo actuator can normally move during operation, regardless of the structure by which it is enclosed. The housing is preferably formed to form an effective hermetic diffusion barrier that is sufficiently "permanent" and unbroken, so that no solid and / or any liquid and / or any gas can pass through the housing. The housing is preferably formed to be completely intact, i.e. in particular to withstand at least 2.5×10 of the enclosed piezo actuator. 8 , particularly preferably 1×10 9 The piezoelectric actuator is "permanently" formed to form a sealed enclosure for the piezo actuator even after many cycles or deflections, respectively.

[0074] To achieve a permanent resistance of the housing to vibrations, the housing can be realized mainly by metallic materials. Alternatively, individual areas of the housing can be made of other non-metallic materials. For example, the bottom and / or cover of the housing can include a ceramic-based material or can be realized by flexible members. Different materials are also conceivable, as long as they provide a sufficient permanent hermetic sealing of the housing even during the operation of the actuator module.

[0075] Particularly preferably, the housing can be produced by deep drawing, as described above. The material of the deep-drawn housing base body can preferably be beryllium copper, and / or stainless steel, and / or steel. The housing cover can preferably be made of beryllium copper, and / or stainless steel, and / or steel, and / or copper, and / or brass. The housing cover can also generally be made of at least one other metal or metal alloy. The wall thickness of the deep-drawn housing base body can, for example, be at least about 0.05 mm, preferably at least about 0.08 mm. For example, the wall thickness of the deep-drawn housing base body can be about 0.09 mm, preferably about 0.1 mm. Larger wall thicknesses are generally also possible, for example 0.15 mm or more.

[0076] To form the deep drawing, the sealable housing, the housing base body and the housing cover can be soldered together. During soldering, the temperature can be preferably less than 200°C, preferably less than 190°C, preferably less than 180°C. Lead solder and / or tin solder and / or mixtures thereof can preferably be used as solder. The use of eutectic solder is particularly advantageous.

[0077] For soldering purposes, the housing base body and / or the housing cover can preferably be coated with solder. For example, a layer with a thickness of about 8 μm of solder can be applied to the edge area of ​​the housing cover to be soldered and / or to the part of the housing base body that receives said edge area before soldering. For soldering purposes, the solder layer on the housing base body and / or on the housing cover can preferably be at least partially melted by induction. For soldering purposes, the frequency of the induction coil can preferably be at least 20 kHz, preferably at least 50 kHz, preferably at least 100 kHz. For example, the frequency can be up to 500 kHz, preferably up to 200 kHz, preferably up to 150 kHz. However, higher frequencies, for example 600 kHz or more, can also be used for soldering purposes.

[0078] In particular by exploiting the skin effect, a reliable, in particular tightly sealed connection can advantageously be formed between the housing base body and the housing cover, in which case the temperature in the housing can be kept as low as possible in order to protect elements arranged therein, such as, for example, the piezo actuator. By exploiting the skin effect, the temperature in the housing interior space / or at the piezo actuator can advantageously be below 200° C. for very short induction times, for example induction times in the range of less than 500 milliseconds.

[0079] It is also generally possible that the housing bottom, the housing jacket and the housing cover are (initially) manufactured as separate elements and then permanently and tightly hermetically connected to one another to form the housing, for example by welding, crimping, soldering, pressing, etc., in which case these three elements then form the housing wall. It is also generally possible to provide two housing halves first and then permanently and tightly hermetically connect them, preferably along their longitudinal extension, to form the housing. However, it is preferred that the housing is at least partially manufactured by deep drawing, as described above.

[0080] Regardless of the specific embodiment, the housing can preferably be formed at least partially in the manner of a folded bellows, in particular in the manner of a folded metal bellows. In the case of a deep-drawn housing, for example, the bellows can be integrated in at least partial regions into the housing base body, in particular into the tubular housing jacket. Such a bellows can be introduced into the housing jacket (after deep-drawing), for example, by hydroforming. A housing cover, firmly connected to the housing jacket and preferably planarly parallel to the housing bottom, can form the upper closure of the housing. The housing base body and the housing cover then form the housing wall in this case.

[0081] Due to the above-mentioned at least partially design of the housing in the manner of a metal bellows, it can be advantageously achieved that the housing is partially formed in an elastic manner, in which case an extension of the piezo actuator in the housing that is as unhindered as possible can occur when a voltage is applied. Particular advantages result in combination with a deep-drawn housing, since the rapid extension of the piezo actuator is here further simplified by the small mass of the housing bottom that is displaced.

[0082] The area of ​​the housing with the bellows can preferably form a defined thermal output area of ​​the housing, via which a particularly efficient heat transfer from the housing wall (housing jacket) to the environment takes place during operation of the actuator module. For example, cooling means of a higher-level machine, for example as part of a jet valve, can be assigned to the thermal output area during operation, the bellows then forming "cooling ribs" around which the cooling medium preferably flows. The temperature of the piezo actuator can thus be set to a specific target value during operation of the actuator module, and in particular can be actively regulated. The thermal output area of ​​the housing can preferably be assigned to a lateral area of ​​the piezo actuator.

[0083] The housing can preferably be at least partially, in particular substantially completely, formed from one or several inorganic substances. The housing can preferably be exclusively composed of inorganic materials to form a tightly sealed housing. It is (also) possible that a tightly sealed encapsulation of the piezo actuator is preferably achieved in that only inorganic materials are used to encapsulate the piezo actuator, in particular to form the housing. The housing can be composed, for example, of beryllium copper, and / or stainless steel, and / or steel, and / or copper, and / or brass, and / or another metal or metal alloy. The housing may therefore be free of organic materials.

[0084] The housing is preferably formed in a tightly sealed manner such that penetration of substances, for example water molecules, through the housing, in particular by osmosis, is prevented or inhibited during operation of the actuator module. The penetration during operation of the actuator module can preferably approach zero. That is to say, the housing can form a penetration barrier or a penetration block, in particular for water molecules, during operation. During operation of the actuator module, the housing can preferably be formed to be permeation-resistant. To prevent penetration, the housing can thus be formed in such a way that no substance can penetrate (penetrate) or pass through the housing during operation.

[0085] A particularly reliable sealing of the piezo actuator, and therefore a permanent shielding of the water molecules, can advantageously be achieved by an exclusively inorganic housing. In the case of other piezo actuators with a case that consists entirely or mainly of organic materials, for example mainly of silicone, it is possible for water molecules to penetrate (permeate) the organic material during the operation of the piezo actuator, especially when a concentration gradient exists through the case. The organic material of such a case, for example a silicone elastomer, often contains free water molecules at a low concentration. Due to the fact that the water molecules are not bound in the organic material, they can move until a concentration compensation occurs between the two sides of the organic material, for example between the outside and the inside of the case.

[0086] The sealed housing can advantageously be formed in such a way that the piezo actuator in the housing can be continuously electrically energized (permanently energized) during a certain period of use of the actuator module. When an electric field is permanently applied during operation, the piezo actuator can advantageously also be effectively shielded by the sealed housing against water molecules of the environment outside the housing. In the case of other piezo actuators with an organic case, for example silicone, water molecules can be transported through and into the case due to the electric field that develops as a result of energizing the piezo actuator, in particular during permanent energization.

[0087] The piezo actuators can preferably be arranged inside the sealed housing such that the respective ends or end regions of the piezo actuators rest directly on the housing base body or the housing bottom and cover, especially when the piezo actuators are in a rest state, thus in a non-extended state. At least one end region of the piezo actuator, for example the actuator head, can preferably be rigidly connected to the housing (cover).

[0088] The housing can preferably be designed in such a way that the surface of the piezo actuator arranged in the housing and the inner surface of the housing wall do not come into direct contact with each other, at least in the region of the housing jacket, i.e. the inner cross section of the housing extending substantially transversely to the longitudinal extension of the housing can preferably be larger than the corresponding cross section of the piezo actuator arranged in the housing.

[0089] To monitor the temperature, at least one temperature sensor can be arranged on the inner surface of the housing wall facing the piezo actuator and / or on the outer surface of the housing wall facing the inner surface and / or inside the potting compound. At least one temperature sensor, preferably two or more temperature sensors, can be preferably arranged in different areas of the piezo actuator surface to detect the temperature gradient along the longitudinal extension of the piezo actuator. At least one temperature sensor can also be arranged directly in the piezo actuator core, thus at the central center point of the transversely cut piezo actuator or in the (edge) area of ​​the piezo actuator radially away therefrom.

[0090] The temperature sensor is preferably connected to an electrical terminal of the housing which penetrates the housing wall in a tightly sealed and electrically insulating manner. Outside the housing, the detected measured values ​​can be fed, for example, to a control means assigned to the actuator module. It should be pointed out that for a feed-through through the housing wall, two or more electrical terminals can be at least temporarily combined such that several electrical terminals penetrate the housing wall by the same feed-through. However, it is equally possible that each electrical terminal is fed separately through the housing wall.

[0091] The electrical terminals can preferably be realized by electrical plugs or terminal pins. The feed-through of the housing, which feeds the respective plug, is preferably made by a respective glass solder tightly integrated into the housing. The respective glass solder or glass feed-through can preferably be integrated into the housing bottom (or housing base body) and / or into the housing cover. The electrical plug or conductor is particularly preferably fed from the inside to the outside of the housing in a manner that is tightly sealed and electrically insulated by the glass solder.

[0092] To manufacture the actuator module, as already described, a potting compound is provided in the cured state, which preferably electrically insulates the housing wall from the piezo actuator. The potting compound itself, i.e. the potting compound without auxiliary substances, is preferably an insulator. The potting compound is preferably arranged in the housing interior space such that substantially the entire piezo actuator surface is electrically insulated with respect to the housing wall.

[0093] In a preferred method, a free-flowing potting compound is produced such that the potting compound to be introduced into the housing comprises a silicone gel, which comprises at least one base silicone and a crosslinking agent. The base silicone can be, for example, a silicone of type SG75L2-30, in which case type SG79L5-30 can be used as a crosslinking agent (respective manufacturer: Elantas, German). As already mentioned, polyurethane or different suitable silicones can also be used, in which case the potting compound should preferably have the above-mentioned properties. Depending on the method of production of the actuator module, for example, a silicone gel with a higher viscosity than the silicone gel mentioned above can also be used.

[0094] In order to provide or produce a free-flowing potting compound in the (first) step, a first half of the total auxiliary material or the total auxiliary material mixture to be used can preferably be mixed with at least a portion of the base silicone. A second half (of the same size) of the auxiliary material or the auxiliary material mixture is preferably mixed with at least a portion of the crosslinker. The first half of the auxiliary material can preferably be mixed with the entire amount of the base silicone provided to produce the potting compound. The second half of the auxiliary material can thus be mixed with the entire amount of the crosslinker.

[0095] In a further (second) step, the respective mixtures thus obtained can preferably be mixed with one another to produce a free-flowing potting compound through which it is introduced into the housing.

[0096] Preferably, a free-flowing potting compound can be produced such that the respective portions of the base silicone and / or crosslinker of the potting compound prior to introduction of the potting compound into the housing are at least about 10 weight percent, preferably at least about 20 weight percent, preferably at least about 25 weight percent, and especially at least about 30 weight percent or more.

[0097] Preferably, the free-flowing potting compound can be produced such that the auxiliary material, in particular the hexagonal boron nitride portion or the auxiliary material mixture portion of the potting compound before the potting compound is introduced into the housing is at least about 10 weight percent, preferably at least about 20 weight percent, preferably at least about 25 weight percent, particularly preferably at least about 30 weight percent, in particular at least about 35 weight percent. The potting compound can be produced such that the auxiliary material or the auxiliary material mixture portion of the (total) free-flowing potting compound is at most about 50 weight percent, preferably at most about 40 weight percent. The auxiliary material, in particular the hexagonal boron nitride, in the form of platelets (auxiliary material platelets) can preferably be arranged in the free-flowing potting compound.

[0098] Due to the fact that the auxiliary material is divided into a number of portions to produce the potting compound and mixed proportionately with the individual components of the potting compound to be produced, the weight percentage of the auxiliary material in the final potting compound that flows freely can advantageously be set as high as possible. The weight percentage of hexagonal boron nitride can be increased, in particular, compared to the method in which the same amount of material (α-BN) is mixed with only one component of the potting compound to be produced, in which case the potting compound flows freely or can still be processed. By "free flowing" is understood a potting compound that is such that it can be introduced into the housing by pressure and / or by inertial forces that occur in particular technically, in order to produce the actuator module through the filling opening of the housing. For example, a "free flowing" potting compound can have a viscosity of at most 1000 cSt (centistokes), preferably at most 500 cSt.

[0099] It can be advantageously achieved by a free-flowing potting compound that the potting compound can be introduced into an otherwise already sealed housing through a very small filling opening, for example having a diameter of 1 mm or less. The potting compound can further advantageously be distributed in the housing interior space such that substantially the entire surface of the piezo actuator is directly adjacent to the hardened potting compound. A free-flowing potting compound in the housing can in particular flow around corners and fill small hollow spaces.

[0100] According to one embodiment of the manufacturing method, the auxiliary material or the auxiliary material mixture, respectively, preferably hexagonal boron nitride, can be arranged in the form of platelets in the free-flowing potting compound, in particular for aligning the auxiliary material particles in the potting compound, in which case a pressure medium is applied to the not yet hardened potting compound (in the not yet sealed housing) for a certain time. It is possible that the filling opening of the housing is not yet sealed in particular. Pressure from outside the housing can be preferably performed in such a way that the respective auxiliary material platelets are arranged in the free-flowing potting compound and / or the solidified potting compound and / or the hardened potting compound such that as a result of the pressure, the longitudinal extension of the respective auxiliary material platelets extends transversely, preferably substantially perpendicularly, to the longitudinal extension of the piezo actuator.

[0101] Preferably, the pressure can be at least 100 bar, preferably at least 200 bar, particularly preferably at least 300 bar or more.

[0102] The pressurization can be performed for at least 1 minute, preferably at least 5 minutes, preferably at least 10 minutes. The pressure medium can be silicone oil. Alternatively or additionally, the pressure medium can be a dry gas and / or a dry gas mixture. The dry gas or dry gas mixture preferably has a water content of at most about 5 parts per million (ppm), preferably at most about 3 ppm, preferably at most about 2 ppm, particularly preferably at most about 1 ppm, particularly preferably at most about 0.5 ppm.

[0103] Alternatively or additionally, the potting compound in the housing can be exposed to a reduced pressure, in particular a vacuum, compared to normal pressure for a certain time. Pulse pressure loading can be performed such that positive and normal or negative pressures are alternately applied to the potting compound in the housing, preferably in each case based on normal pressure.

[0104] The pulsed or repeated pressure load can advantageously contribute to the fact that substantially all auxiliary material particles or auxiliary material platelets have a specific alignment in the hardened potting compound, especially during operation of the piezoelectric actuator.

[0105] According to one embodiment of the manufacturing method, the auxiliary material or auxiliary material mixture in the form of platelets, preferably hexagonal boron nitride, can be arranged in a free-flowing potting compound, in particular for aligning the auxiliary material particles, in which case the provision of the potting compound can be carried out as described above. In the case of this embodiment, the potting compound, preferably not yet hardened, can be subjected to specific, in particular technically occurring, inertial forces in an unsealed or sealed housing. The free-flowing potting compound and / or the solidified potting compound and / or the hardened potting compound can preferably be subjected to, in particular technically occurring, centrifugal forces, so that as a result of the centrifugal forces, the respective auxiliary material platelets are arranged in the free-flowing potting compound and / or the solidified potting compound and / or the hardened potting compound such that the longitudinal extension of the respective auxiliary material extends transversely, preferably substantially perpendicularly to the longitudinal extension of the piezo actuator.

[0106] In the case of this embodiment, the auxiliary material or auxiliary material mixture in the form of platelets, in particular hexagonal boron nitride, can particularly preferably be arranged in a free-flowing potting compound, which is then introduced into the housing itself by specific, preferably technically generated, inertial forces, in particular centrifugal forces, acting on the housing and / or the potting compound, which are preferably applied in such a way that they act substantially perpendicular to the base surface of the respective auxiliary material particles when introducing and / or hardening the potting compound, in particular based on the spatial arrangement or alignment of these particles in the hardened potting compound.

[0107] The technically occurring centrifugal forces can act in particular on the housing and / or the potting compound in such a way that the respective auxiliary material platelet, as a result of the centrifugal forces with respect to its longitudinal extension, is arranged transversely, preferably substantially perpendicularly, to the longitudinal extension of the piezoelectric actuator in the free-flowing potting compound and / or in the solidified potting compound and / or in the hardened potting compound.

[0108] Preferably, the method can be performed such that the inertial forces act on the potting compound, in particular on the auxiliary substance in the potting compound, substantially in the direction of longitudinal extension of the housing, preferably in the direction of longitudinal extension of the piezo actuator in the housing. The inertial forces can preferably act on the potting compound and / or on the auxiliary substance primarily perpendicular to the shortest distance between the piezo actuator and the housing wall, in particular the housing jacket.

[0109] The potting compound with the auxiliary material platelets can advantageously be introduced into the housing by inertial forces, and a specific advantageous alignment of the auxiliary material platelets in the potting compound can be achieved. The manufacturing method can therefore be carried out particularly effectively, and a specific alignment of substantially all of the auxiliary material particles in the (hardened) potting compound can be achieved. The inertial forces can preferably be technically generated centrifugal forces.

[0110] In the case of the present manufacturing method, the mass percentage of the auxiliary material, in particular hexagonal boron nitride, can be significantly increased in the hardened potting compound by using inertial forces that align in a specific way with respect to the housing, compared to other methods. For example, a portion of hexagonal boron nitride of up to 70 weight percent can be achieved in the hardened potting compound in the housing by a specific method, in which case the free-flowing potting compound has, for example, only a portion of hexagonal boron nitride of 35 weight percent. On the one hand, the mass percentage of α-BN can thus be advantageously set so that the potting compound is barely free-flowing, and on the other hand, the mass percentage of α-BN in the hardened potting compound is significantly increased by the present manufacturing method compared to the initial value. The thermal conductivity of the potting compound can thus be increased in order to achieve a certain high heat dissipation from the piezo actuator.

[0111] The two above-mentioned embodiments can generally be combined with each other. For example, a free-flowing potting compound can be introduced into the housing by technically generated centrifugal forces. The alignment of the auxiliary material particles in the potting compound can then be performed, for example, by pressurizing the potting compound in the housing. It is also possible to introduce a free-flowing potting compound into the housing by centrifugal forces, in which case pressurization of the potting compound is then performed and centrifugal forces are subsequently applied once again.

[0112] Regardless of the specific embodiment, it may be provided in the manufacturing method that at least the housing and / or the piezo actuator and / or the auxiliary material are subjected to a pretreatment before filling the potting compound into the housing. The pretreatment may preferably include exposing the components to a vacuum for a certain period of time and / or heating to a certain temperature.

[0113] For heating and / or evacuation purposes, the housing can preferably comprise a deep-drawn housing base body and a housing cover firmly connected thereto, in which the piezo actuator is arranged in the housing and the connection between the components of the housing is such that a tight seal of the housing can be (later) formed therethrough. The housing cover preferably has at least one sealable (filling) opening that can be tightly sealed to form the final housing. Such a housing (with the installed piezo actuator) as well as the auxiliary substance or auxiliary substance mixture are preferably subjected to a vacuum, for example of 10-100 mbar, in particular on the outside of the housing. The heating of these components is preferably performed simultaneously. The manufacturing method can therefore preferably include a vacuum drying process. For the vacuum drying process, the above-mentioned components can be placed in a heatable vacuum container, for example in a vacuum chamber.

[0114] Preferably, heating is carried out to a temperature of at least 60° C., preferably to a temperature of at least 90° C., preferably to a temperature of at least 110° C., and / or to a temperature of up to 190° C., preferably to a temperature of up to 150° C., preferably to a temperature of up to 140° C. Heating and / or evacuation can be carried out for at least 1 hour, preferably at least 2 hours, preferably at least 3 hours, particularly preferably at least 4 hours, in particular at least 5 hours, or more.

[0115] Heating of the element is preferably performed to a temperature of 130° C. for a period of 48 hours. Particularly preferably, the element is placed in a vacuum of about 10 mbar during heating. Regardless of the specific heating parameters, heating can preferably be performed by infrared radiation.

[0116] Advantageously, it is thereby already achievable that the interior space of the housing, or each of the above-mentioned elements arranged inside the sealed housing to be produced, is as completely free as possible from H2O.

[0117] During heating and / or evacuation, in particular during heating and / or evacuation, in particular under vacuum, a voltage can preferably be applied to the piezo actuator at least once or briefly. In the vacuum drying process, a voltage can preferably be applied to the piezo actuator several times, in particular continuously during the entire period of heating under vacuum. The voltage can preferably be the voltage that is maximally permissible for the piezo actuator. This approach can contribute to the fact that the elements to be dried or that have been dried, in particular the piezo actuator in the housing, are particularly effectively and reliably free from H2O molecules.

[0118] The vacuum drying process can preferably be carried out such that the vacuum vessel is flooded with protective gas at least once. The protective gas can preferably be applied to the elements to be dried for a certain period of time, in particular for a period of about 30 seconds. A pressure of about 600 mbar can preferably be generated in the vacuum vessel during the flooding with protective gas. At the end of the application of the protective gas, the original vacuum can preferably be applied again. The protective gas can be a dried inert gas, for example dry argon.

[0119] The vacuum drying process can preferably be carried out such that the vacuum vessel is temporarily filled with protective gas twice or several times. After each step of filling with protective gas, the vacuum can preferably be applied again. Particularly preferably, the vacuum drying process can be carried out for 48 hours, whereby the vacuum vessel is temporarily filled with protective gas, in particular with dry argon, at intervals of about 2 hours. The duration of each filling can be about 30 seconds. By applying protective gas to the elements and then evacuating, it can advantageously be achieved that during the operation of the piezo actuator, undesirable molecules (for example H2O, H, O2) can be particularly reliably removed from the elements to be dried, in particular from the already partially sealed housing.

[0120] It can be provided in the manufacturing method that at least a part of the piezo actuator, in particular at least a part of the surface of the piezo actuator and / or at least a part of the internal housing wall is cleaned by plasma cleaning. The plasma cleaning can preferably be carried out in a vacuum. The plasma cleaning can in particular be integrated into the above-mentioned vacuum drying process. It is also generally possible that the plasma cleaning is carried out independently of the vacuum drying process. The plasma cleaning can then form, for example, an independent step of the manufacturing method. Regardless of the specific embodiment, the plasma cleaning is preferably carried out before filling the potting compound into the housing.

[0121] The plasma cleaning can preferably be performed in an enclosure with a piezo actuator arranged therein. The enclosure is preferably already partially sealed, in which case the enclosure interior space is accessible from the outside via a sealable (fill) opening in the enclosure cover. The piezo actuator can be attached at least to the enclosure cover, preferably also to the opposite enclosure bottom. The plasma cleaning can preferably be performed during the above-mentioned vacuum drying process. During the vacuum drying, a plasma can preferably be generated once or repeatedly for each specific period. It is also possible for the plasma to be generated during the entire vacuum drying process. For plasma cleaning, the enclosure with the piezo actuator can thus be placed in the same vacuum vessel (as the processing chamber) in which the vacuum drying process is particularly performed simultaneously. Advantageously, the generation of the plasma can be facilitated by a vacuum. Even more advantageously, the method can be performed more effectively by this combination. Alternatively, the plasma cleaning can also be performed on an enclosure that has previously been subjected to a vacuum drying process.

[0122] The method can be performed such that the piezo actuator in the housing forms an electric pole during plasma cleaning. Preferably, an electric current can be applied to two electric terminals or connection poles of the piezo actuator. The two electric terminals of the piezo actuator can in particular be short-circuited during plasma cleaning to avoid a voltage potential at the piezo actuator. To generate an electric field, a further electric pole can be formed through the housing, in particular through the deep-drawn housing base body. A plasma can then be generated between the housing and the piezo actuator surface. The housing can preferably form a ground connection. The two electric poles are preferably connected to a voltage source located outside the vacuum vessel.

[0123] The method can also be carried out in such a way that the connection poles of the piezo actuator in each case form electric poles for generating plasma. The plasma can then be generated locally (within certain limits) between the two connection poles of the piezo actuator. A combination of the two embodiments is also possible, in particular in the same vacuum drying process.

[0124] The plasma can be generated by a direct current voltage applied between two electric poles (as electrodes), for example a voltage of at least 100 volts, preferably at least about 200 volts.

[0125] The plasma can preferably be generated in or with argon. This has the advantage that the plasma cleaning can be directly integrated into the above-mentioned vacuum drying process, since argon is preferably used therein as protective gas. More advantageously, the plasma can already be formed in argon starting from a voltage of about 100 volts. Alternatively, oxygen can be used for the plasma cleaning. This can be advantageous since oxygen has a relatively strong cleaning effect.

[0126] Advantageously, contaminants can be particularly effectively removed from the piezo actuator surface and / or from the inside of the housing by such a plasma. Such contamination or contamination on said surfaces is caused in the manufacturing process, for example during the introduction of the piezo actuator into the housing and / or during soldering of the housing cover, and is often of organic origin. In particular, the piezo actuator can be exposed to contamination by several processing steps, for example also by contact. These contaminations can adversely affect the operation of the encapsulated piezo actuator and thus reduce the life span of the actuator module. Simultaneous efficient cleaning of the entire piezo actuator surface or of the internal housing wall can advantageously be achieved by means of plasma, in which case the removed contaminants or their components can be removed as gas from the housing.

[0127] The piezo actuator surface can advantageously be cleaned and purified from contamination by plasma in the area between the connecting poles of the piezo actuator, in particular between the outer electrodes. During operation, such contamination can generate leakage currents or short circuits between the positive and negative poles of the piezo actuator, which are located in close proximity to each other. The inside of the housing bottom, the inside of the housing jacket, the inside of the preferably deep-drawn housing base body and the inside of the housing cover can, for example, be further cleaned by plasma (at least in the areas not covered by the piezo actuator). Due to the fact that the piezo actuator is placed in the housing as intended during plasma cleaning, in which case the housing is already largely sealed, subsequent contamination of the piezo actuator and / or of the inside of the housing wall can be avoided, if possible. Particular advantages can be achieved when combining a vacuum drying process with a simultaneous plasma cleaning. Contaminants can be at least mainly evaporated by plasma, so that they can be taken out of the housing as gas. Preferably, the vacuum can be routinely increased, for example to about 500 mbar, for a predetermined time, for example for a few seconds, by flowing in protective gas, preferably argon gas, during the vacuum drying process, and then reduced again. By periodically flooding with protective gas and then reducing the vacuum, gases or particles optionally contained therein, for example resulting from evaporated contamination, can be removed from the housing, in particular released therefrom, through unsealed (filled) openings in the housing.

[0128] The vacuum can preferably be released after the drying process by heat and vacuum in such a way. It is particularly possible that a drying gas is supplied at the end of the plasma cleaning to the dried components and / or to the plasma-cleaned piezo actuator or to the housing, respectively, to be applied or filled with the drying gas, said gas being preferably heavier than air, so that said gas, for example, enters and remains in the upright housing, in which case the inflow of air is prevented. The drying gas can preferably be argon, as described later.

[0129] By using dried auxiliary substances, preferably by using powdered dried hexagonal boron nitride, the further or base components of the potting compound, i.e. the base silicone and the crosslinker, can be evacuated and / or dried before being brought together with the auxiliary substances, for example as previously described for the housing, to provide the potting compound. The drying of the housing and the drying of the base components of the potting compound as well as the drying of the auxiliary substances can be carried out, for example, in a common method step, in particular in the same vacuum chamber and / or under the same parameters. Drying gas can be applied to the dried (base) components of the potting compound by releasing the vacuum, preferably to form a protective gas atmosphere, in particular with respect to the ambient air. It is pointed out that evacuating and / or heating the base components of the potting compound are optional steps and can be preceded, for example, in the case of a manufacturing method based on inertial forces.

[0130] Preferably, a dry gas or gas mixture, in particular at least an inert gas, can be applied to the housing and / or to the piezo actuator and / or to the auxiliary material and / or to the base component of the potting compound after heating and / or evacuation, in particular to the housing with the piezo actuator after plasma cleaning, preferably to form a protective gas atmosphere. Preferably, the dry gas (mixture) of the protective gas atmosphere has a residual moisture content of at most about 5 ppm, preferably at most about 3 ppm, preferably at most about 2 ppm, particularly preferably at most about 1 ppm, particularly preferably at most about 0.5 ppm. The dry gas preferably has a density higher than air, for example pure dry argon.

[0131] Regardless of the specific embodiment of the method, the vacuum in which the housing and / or the piezo actuator and / or the auxiliary substance and / or the base component of the potting compound (not mixed) is placed can be replaced directly with a protective gas atmosphere, particularly preferably. The evacuation and / or heating and / or the formation of a protective gas atmosphere can be carried out in a vacuum chamber which is preferably opened against gravity, in which case the dried components are placed in a volume of dry gas, particularly completely surrounded by it. The housing and / or the piezo actuator and / or the auxiliary substance and / or the base component of the potting compound are also preferably sealed against the surrounding atmosphere by high density dry gas (as a protective gas atmosphere) even by releasing the vacuum.

[0132] Advantageously, when using such a gas, it can be ensured that no moisture can get into the housing and / or auxiliary material, even though the vacuum has been released and the housing is not (yet) sealed. Dry gases in particular can collect in the housing and can be subsequently displaced from the housing by the incoming potting compound, for example by centrifugation, as described later. It is advantageous to use argon with a residual moisture content of less than 3 ppm, since a sufficiently safe process environment can be achieved therewith for the piezo actuator in the housing and the input costs are moderate compared to the case of non-dried gases.

[0133] At the end of the above drying process, the supply of the potting compound, in particular the mixing of the base component of the potting compound with the dried auxiliary material, can preferably be carried out in such a (protective gas) atmosphere of dry gas, for example argon with less than 3 ppm residual moisture.As already mentioned, preferably half of the auxiliary material can be mixed with the base silicone and the crosslinking agent before these mixtures thus obtained are brought together to produce a free-flowing potting compound.Preferably, the potting compound finally produced in this way is further processed immediately after bringing these materials together in order to achieve the alignment of the auxiliary material platelets as effective as possible in the potting compound in the housing (regardless of the embodiment of the method).

[0134] For introduction into the housing, regardless of the embodiment of the method, preferably the finally produced free-flowing potting compound has a viscosity of at least about 100 cSt, preferably at least about 200 cSt, preferably at least about 300 cSt, and / or at most about 1000 cSt, preferably at most about 750 cSt, preferably at most about 500 cSt. The viscosity can generally be higher. Preferably, the free-flowing potting compound is such that it can be introduced into the housing by technically generated inertial forces, preferably by centrifugation.

[0135] In one embodiment of the method, the potting compound thus produced can preferably be pressed or injected through the filling opening into the housing with a pressure of at least 1 bar, preferably at least 2 bar, in which case in particular the inflow of (air) moisture into the housing and / or into the potting compound can be prevented during the introduction by keeping the relevant elements in a protective gas atmosphere of dry gas. Advantageously, the dry gas, e.g. argon, located in the housing before filling can be displaced from the housing when the potting compound is pressed in, in which case essentially no air moisture can enter the housing. In order to align the auxiliary material platelets in the potting compound, a high pressure, e.g. 300 bar, can subsequently be applied to the housing and / or the potting compound, as already described. The filling opening can be subsequently sealed by pressing in a ball.

[0136] Alternatively, the supply of the potting compound, in particular the mixing of the base component with the auxiliary material, can also be carried out under vacuum, for example at a pressure of 10 mbar to 100 mbar. The production of the potting compound can in particular be carried out by continuously keeping the housing and / or the auxiliary material and / or the piezo actuator and / or the base component of the potting compound under vacuum. The produced free-flowing potting compound can also be evacuated (once again) before being introduced into the housing. The approach described above can be advantageous, for example, when the potting compound as described is introduced into the housing by pressure, because the outflow of the potting compound and / or the gas contained therein from the filling opening of the housing as a result of the pressurization to align the auxiliary material platelets can be prevented. However, in the case of this embodiment, it is also possible, as mentioned above, that the supply of the potting compound and / or the introduction of the potting compound into the housing takes place under a protective gas atmosphere (without a vacuum), which makes filling the housing technically easier.

[0137] In the case of one embodiment of the method, the finally produced potting compound can be provided in a potting storage container. The potting compound can in particular be stored in the potting storage container such that it is sealed against the surrounding atmosphere by a protective gas atmosphere. In order to introduce the potting compound into the housing, the potting storage container or the potting compound storage container can be tightly connected to the filling opening of the housing. The potting storage container can in particular be connected to the filling opening so as to form a seal, for example via an injection needle. Advantageously, a gas, for example argon, can escape from the housing through the injection needle during filling and during dripping of the potting compound into the potting storage container, thereby achieving a reduction in the viscosity of the potting compound in the storage container and optionally in the housing, in which case the individual components of the potting compound are mixed in the storage container and optionally also in the housing. It is further advantageously achievable thereby that after the housing is completely filled with the potting compound, no excess potting compound escapes from the filling or loading opening and contaminates, for example, a centrifuge beaker. The housing interior space of the housing for introducing the potting compound is preferably substantially completely filled with a dry gas, in particular with a protective gas atmosphere.

[0138] The arrangement of the potting storage container and the housing tightly connected thereto for introducing the potting compound into the housing can preferably be centrifuged. The centrifugation can in particular be performed such that the axis of rotation extends substantially perpendicular to the longitudinal extension of the housing and / or the longitudinal extension of the piezo actuator in the housing. The direction of introduction of the potting compound into the housing can in particular be substantially perpendicular to the axis of rotation and substantially parallel to the longitudinal extension of the housing.

[0139] The housing and / or the potting storage container coupled thereto can preferably be pivotally mounted for centrifugation. The housing and / or the potting storage container coupled thereto can be pivotally mounted such that the longitudinal extension of the housing and / or the piezo actuator as a result of centrifugation is gradually extended substantially transversely to the axis of rotation, particularly when a target acceleration is reached.

[0140] Centrifugation can be carried out, for example, by a beaker centrifuge. Preferably, centrifugation is performed for at least 30 seconds and / or at most 60 seconds. Preferably, centrifugation is performed at an acceleration of at least 8000 g and / or at most 10000 g. To further increase the concentration of the auxiliary substances in the potting compound in the housing, the duration of centrifugation can be increased and / or for example the acceleration can be increased.

[0141] The solidification of the potting compound in the housing can take place at room temperature, preferably under a protective gas atmosphere, or alternatively, it can be accelerated at temperatures up to 90° C. The opening can then be sealed by pushing in a ball.

[0142] In the case of the method, it is advantageously possible that the produced, e.g. evacuated and heated, optionally plasma cleaned, housing with the piezo actuator therein can be transferred into the centrifuge together with the volume of dry gas located in the housing without special safety measures, in which case the housing can be first connected, in particular under ambient atmosphere or without special conditions, e.g. to a potting storage container in the centrifuge. Advantageously, the inflow of air moisture (through the unsealed filling opening) into the housing filled with dense gas can be prevented.

[0143] As a result of the centrifugation, the dry gas in the housing can be further advantageously pushed out of the housing by the incoming potting compound. This means that the volume of the gas can be directly replaced by a corresponding volume of the potting compound, so that air moisture cannot reach the inside of the housing. A tightly sealable housing with a piezo actuator arranged therein can thus be provided with relatively simple technical means, in which case it is ensured by the manufacturing method that the inside of the sealed housing is substantially free of any moisture. The piezo actuator is therefore also reliably protected against H2O molecules. Further advantageously, the supply of the potting compound, for example by mixing dried boron nitride with non-dried base silicone and crosslinker, and / or the transfer of the free-flowing potting compound into the potting storage container can be performed outside the protective gas atmosphere, for example in ambient air.

[0144] In an optional step of the method, for example, directional vibrations can be generated in the not yet solidified potting compound, preferably in the auxiliary material, in order to align the auxiliary material in the potting compound. Preferably, directional vibrations having a specific frequency and / or amplitude can be generated, for example, by controlled shaking of the potting compound in an enclosure.

[0145] Alternatively or additionally, the unsolidified potting compound in the housing, and in particular the auxiliary material therein, can be placed in an external electric field and / or an external magnetic field for a specific period of time to align the auxiliary material.

[0146] Alternatively or additionally, the not yet solidified potting compound in the housing, and in particular the auxiliary material therein, can be subjected to temperature treatment at at least two different temperatures to align the auxiliary material.

[0147] Alternatively or additionally, the method can be carried out such that the viscosity of the not yet solidified potting compound in the housing is reduced by shearing compared to the untreated potting compound in order to align the auxiliary material in the potting compound. Preferably, a certain viscosity of the potting compound can be achieved, in particular by sound or ultrasound.

[0148] Advantageously, the above-mentioned optional method steps contribute to the fact that a specific alignment or arrangement of the auxiliary substances in the potting compound, respectively, is achieved and / or promoted. The method steps can be integrated into the manufacturing method individually or in a specific combination and at different times. For example, a modification of the viscosity of the potting compound can be performed before centrifugation to enhance the centrifugation effect, in which case a pressure treatment of the potting compound can be performed, for example, after centrifugation or between two centrifugation steps. It is generally possible that the potting compound for performing one of these optional method steps is not (yet) placed in the housing.

[0149] It may be optionally provided in the method that the auxiliary substance and at least one base component of the potting compound, for example silicone gel, are introduced into the housing in a time-offset manner, in particular sequentially. For example, a stepwise introduction is also possible, in which a potting compound containing a first portion of the auxiliary substance is first introduced into the housing, and a second portion of the (pure) auxiliary substance is then introduced into the potting compound in the housing. Thus, a (final) potting compound can be produced in the housing, for example with a certain mass percentage of the auxiliary substance.

[0150] In the potting storage container, for example, only one or several base components can be provided first, for example, silicone gel, to form a free-flowing potting compound. The silicone gel can be introduced into the housing by inertial forces, for example, by centrifugation. Preferably, the housing can be substantially completely filled with silicone gel, in which case partial filling is also possible. Preferably, an auxiliary material, preferably powdered boron nitride, can then be introduced into the (remaining) silicone gel in said storage container, in which case the auxiliary material is moved into the silicone gel in the housing by inertial forces to form the potting compound. Preferably, the auxiliary material can be subsequently introduced into said storage container and / or housing.

[0151] Advantageously, the volumetric flow of the auxiliary material into the housing can be controlled by sequential introduction. Advantageously, a specific spatial distribution of the auxiliary material in the potting compound can be formed hereby, in particular by a position-dependent density. For example, it is also possible to form at least two regions with different densities of the auxiliary material and / or a density gradient in the potting compound.

[0152] Further, the method can generally be practiced such that at least two different auxiliary substances and / or at least two different types of potting compounds, e.g., having different physical and / or chemical properties, are sequentially introduced into the housing.

[0153] The invention further relates to an actuator module having at least the features of an actuator module according to the invention, said actuator module being obtainable by the manufacturing method described above.

[0154] The invention will be described in more detail below once again on the basis of exemplary embodiments with reference to the accompanying drawings, in which identical components in the different figures are provided with the same reference signs and in which the figures are generally not drawn to scale. [Brief description of the drawings]

[0155] [Figure 1] 1 shows a schematic cross-section through a metering system according to the invention; [Diagram 2] 1 shows a schematic perspective view of an actuator module according to the present invention; [Diagram 3] 1 shows a schematic cross-section through an actuator module according to the invention; [Figure 4] 1 shows a schematic cross-section through an actuator module according to the invention; [Figure 5A] 1 shows a schematic, greatly enlarged view of a portion of an actuator module according to the invention; [Figure 5B] FIG. 2 shows a schematic diagram of an auxiliary material platelet. [Figure 6] 1 shows a schematic cross-section through an actuator module according to the invention; [Figure 7] 1 shows a schematic cross-section through an actuator module according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0156] The manufacture of an actuator module according to the invention is described exemplarily below on the basis of a possible embodiment of the manufacturing method. For clarity, the method is described on the basis of only one actuator module, although several actuator modules can be manufactured in parallel in the method.

[0157] In a first step, a sealable container is provided, the housing having at least one housing bottom and a housing jacket, preferably a deep-drawn housing base body, firmly connected thereto. A (not yet sealed) housing cover is provided with at least two tightly sealed and electrically insulated electrical terminals, for example two feedthroughs, for wiring the piezo actuator. The piezo actuator is firmly placed on the housing cover, the connection poles of the piezo actuator being in contact in each case with the electrical terminals, for example by soldering. The housing cover has at least one unsealed filling opening for the potting compound, for example a circular hole with a diameter of about 1 mm.

[0158] In a further step, the piezo actuator is introduced into the housing, in particular into the housing base body, in which case the cover and the housing jacket are subsequently firmly connected to one another, preferably by soldering, or by welding, crimping, pressing, etc., to form the housing.

[0159] In a further step, the housing with the piezo actuator is transferred into a vacuum chamber. It is also generally possible to carry out the introduction of the piezo actuator into the housing in the vacuum chamber. A defined amount of hexagonal boron nitride is subsequently provided in the vacuum chamber for introduction into the respective housing. The hexagonal boron nitride can be, for example, a mixture of two boron nitride powders each having a different average particle size.

[0160] The boron nitride as well as the housing with the piezo actuator located therein is subsequently heated in vacuum (10 mbar) to a temperature of 110° C. Heating is performed by infrared irradiation, for example for a period of 5 hours. The housing with the piezo actuator located therein can optionally be subjected to plasma cleaning during vacuum drying.

[0161] After evacuation and heating, the vacuum is released in that the vacuum chamber is filled or saturated with an ultra-dry inert gas (e.g., residual moisture <1 ppm). The inert gas forms a protective gas atmosphere in the (open) vacuum chamber, where the housing and the boron nitride are placed, for example, at the bottom of the vacuum chamber, so that the above-mentioned components are kept under a mirror of dry gas.

[0162] To provide the potting compound, half of the boron nitride is mixed in each case with the base silicone and the crosslinker before the mixture thus obtained is brought together for the production of the potting compound. Mixing can be carried out under ambient air or under a protective gas atmosphere.

[0163] The potting compound is transferred, optionally sealed from the surrounding atmosphere, into a potting compound storage container.

[0164] To fill a (single) housing, for example, at least 1.6 g of hexagonal boron nitride, at least 0.85 g of (base) silicone, and at least 1.3 g of hardener or crosslinker can be mixed. The applied volume of potting compound is primarily a function of the volume of the housing interior space and is preferably calculated so that at the end of the centrifugation a certain residue of potting compound remains outside the housing or in the potting storage container. Thus, advantageously, it can be determined in a simple manner that the maximum possible volume of silicone gel and / or boron nitride has been forced into the housing by centrifugation, and the housing is optimally filled.

[0165] More advantageously, different ratios between boron nitride and base silicone or crosslinker, respectively, can also be selected within certain limits, since the maximum possible concentration of boron nitride is realized automatically in the housing for a specific manufacturing method by centrifugation, preferably as a function of the centrifugation parameters. In combination with a small surplus of potting compound at the end of centrifugation, it can be ensured in a simple manner that the potting compound in the housing has the maximum possible density of boron nitride.

[0166] In a further step, the housing is removed from the protective gas atmosphere and transferred directly into a beaker centrifuge, with the unsealed filling opening preferably facing away from the vertical direction at least before the start of centrifugation, during said transfer and / or in said centrifuge. Advantageously, the housing is substantially completely filled with a dry gas having a density higher than air, so that ambient air does not enter the housing during said transfer. A potting storage container is tightly coupled to the filling opening of said housing before insertion into said centrifuge and / or in said centrifuge, respectively.

[0167] The potting storage container and housing arrangement is then centrifuged for 30 seconds at a (target) acceleration of 8000 g, where the arrangement is pivotally mounted, such that when the target acceleration is reached, the longitudinal extension of the housing and / or the longitudinal extension of the piezoelectric actuator extends substantially perpendicular to the axis of rotation of the centrifuge.

[0168] By centrifugation, on the one hand, the potting compound is introduced into the housing, and on the other hand, a preferred alignment of the boron nitride platelets with respect to the longitudinal extension of the piezo actuator is achieved. Furthermore, advantageously, it can be achieved by centrifugation that mainly boron nitride enters the housing, so that the mass percentage of boron nitride can be increased in the hardened potting compound compared to the initial concentration in the free-flowing potting compound. Furthermore, advantageously, it can be achieved by centrifugation that the dry gas present in the housing is directly replaced by the same volume of incoming potting compound. It is thereby ensured that moisture cannot enter the housing during the manufacture of the actuator module.

[0169] The volume of the free-flowing potting compound can be determined so that the entire housing interior space between the piezo actuator and the housing wall is filled with the hardened potting compound. A small volume of the housing interior space can be optionally left free of potting compound to form the elongation region. To form the elongation region, a thin small rod, for example a particularly thin small Teflon rod, can be pressed all over through the filling opening onto the base of the housing after filling with potting compound. After solidification of the potting compound, the small rod can be easily pulled out, in which case this is preferably done under an argon atmosphere, and / or argon or a different inert gas is filled into the formed hollow space after pulling out the small rod, for example via a needle, before the filling opening is sealed by a sealing ball. Advantageously, a hollow space extending substantially over the entire length of the housing can be formed in the hardened potting compound therethrough, in which case the increase in pressure from the inside is distributed as evenly as possible over the entire longitudinal extension of the housing during extension of the potting compound during operation.

[0170] Preferably, the composition and / or centrifugation parameters of the free-flowing potting compound are selected such that the auxiliary material particles are arranged in the hardened potting compound to be evenly distributed along the entire longitudinal extension of the piezoelectric actuator, in other words, preferably the concentrations of the auxiliary material particles in the various regions of the potting compound are primarily of the same order of magnitude.

[0171] Solidification of the potting compound in the housing can take place at room temperature or at temperatures up to 90° C. The housing is substantially sealed, optionally by containing a small volume of dry gas. For this, a steel or ceramic ball with a diameter slightly larger than the filling opening can be pressed into the filling opening with a large force (e.g., 600 N).

[0172] The actuator module thus produced can be used, for example, in a metering system for substances ranging from metered liquids to viscous metered substances, for example in a jet valve, which is shown quite diagrammatically in cross section in Figure 1. Due to the fact that the basic construction of a jet valve of this type is known, only the essential elements are described below.

[0173] As substantial elements, the metering system 50 comprises an actuator assembly 51 as well as a fluid assembly 52 releasably connected thereto, said connection being effected here in a representative manner by means of a screw 62. The actuator assembly 51 comprises substantially all components ensuring the actuation or movement, respectively, of the discharge element 53 or of the tappet 53 of the fluid assembly 52 at the nozzle 54.

[0174] In addition to the nozzle 54 and the supply channel 56 for the metered substance to the nozzle 54, the fluid assembly 52 comprises all further parts that are in direct contact with the metered substance, as well as further elements necessary for assembling the respective parts that come into contact with the metered substance or metering medium, respectively, or for holding them in their position on the fluid assembly 52, respectively.

[0175] In the exemplary embodiment of the metering system 50 shown here, the actuator assembly 51 comprises a housing block 57 having two internal chambers, namely, on the one hand, an actuator chamber 58 with an actuator module 1 located therein, the actuator module 1 having at least one piezo actuator 2 hermetically enclosed in a housing 3 (FIG. 3), and, on the other hand, an action chamber 59 into which a movable discharge element 53 of the fluid assembly 52, here a tappet 53, projects. The tappet 53 is actuated via a lever 60 which projects from the actuator chamber 58 into the action chamber 59 via an opening 61, so that the metered substance to be metered is discharged from the fluid assembly 52 in the desired amount at the desired time in a discharge direction AR through the nozzle 54. The tappet 53 seals the nozzle opening 55 and therefore also serves as a sealing element 53. However, due to the fact that the largest part of the medium is simply discharged from the nozzle opening 54 by the tappet 53 as the tappet 53 moves in the discharge direction AR towards the nozzle opening 55, it is referred to here as the discharge element 53.

[0176] To control the piezo actuators 2 (FIG. 3), the actuator modules 1 are connected electrically or by signals, respectively, to a control means 5 which can also be formed, for example, as part of a weighing system 50. The connection to the control means 5 is made by means of a connecting cable 5′ which is connected at the end side to an actuator module control terminal 28, for example a suitable plug 28.

[0177] The actuator module control terminals 28 in each case contact electrical terminals 21 in the housing 3, here two contact pins 21 each fed through the housing wall of the housing 3 in a tightly sealed and electrically insulating manner. In Fig. 1 the actuator module 1 comprises a total of four contact pins 21, 22 arranged in the housing cover 32. The two outer contact pins 21 here serve respectively for the purpose of controlling the piezo actuator or for communication between the piezo actuator and the control means 5.

[0178] The two contact pins 22 shown in the center are used here to transmit the measured values ​​from the temperature sensors 27 (FIG. 3) from the housing 3 to the control means 5. For this purpose, the contact pins 22 are in each case connected in the housing 3 on one side to the control means 5 by means of a temperature sensor terminal 28′ and on the other side to an individual temperature sensor 27 (not shown). It is also possible, for example, for the measured values ​​from several temperature sensors 27 to be transmitted to the control means 5 via the contact pins 22 in a spatially resolved manner.

[0179] The piezo actuator 2 (FIG. 3) arranged in the housing 3, and via it also the housing 3, can be extended and retracted again in the longitudinal direction of the actuator chamber 58 according to wiring by the control means 5. The actuator module 1 can be arranged in the actuator chamber 58 from above and mounted therein in a height-adjustable manner, allowing in this case a precise adjustment of the actuator module 1 with respect to the movement mechanism 63. In the case shown here, the housing cover 32 supports itself inside the actuator chamber 58 via a support element 58′, which here serves as an upper abutment and can be adjusted, for example by a screwing action (not shown), for the adjustment of the actuator module 1. The actuator module 1 is thus mounted here via a pressure piece 64 tapered sharply downwards on a lever 60, which rests on a lever bearing 65. The lever 60 can be tilted about a tilt axis K via said lever bearing 65, so that a lever arm of the lever 60 projects through the opening 61 into the action chamber 59. At the end of the lever arm, the latter has a contact surface 66 facing towards the tappet 53 of the fluid assembly 52 connected to the actuator assembly 51 and pressing onto a contact surface 67 of a tappet head 68.

[0180] In the case of the exemplary embodiment shown, this is provided in that the contact surface 66 of the lever 60 is in permanent contact with the contact surface 67 of the tappet head 68, in that the tappet spring 69 presses the tappet head 68 from below against the lever 60. However, it is also generally possible that there is a spacing between the tappet 53 and the lever 60 in the initial or rest position, respectively, of the tappet spring 69. In order to provide an almost constant preload of the drive system, the lever 60 is pressed here towards the top by an actuator spring 70 on the end where it contacts the tappet 53.

[0181] The tappet 53 is supported by a tappet spring 69 on a tappet bearing 71 adjacent to the bottom to a tappet seal 72. The tappet spring 69 now presses the tappet head 68 upwards, away from the tappet bearing 71 in the axial direction. The tappet tip 73 is therefore also pressed away from the sealing seat 74 of the nozzle 54. This means that without external pressure on the tappet head 68 from above, the nozzle opening 55 is also not sealed in the rest (non-extended) state of the piezo actuator 2 (Figure 3).

[0182] The nozzle 54 is supplied with the metered substance via the nozzle chamber 75 as well as via an adjacent supply channel 56 which is connected to a metered substance reservoir 76. The fluid assembly 52 comprises a frame part having heating means 77 which is connected to the control means 5 by a heating connection cable 78 and which may also comprise further components.

[0183] The metering system 50 comprises here a controllable cooling means 80, shown in an exemplary and schematic manner. The cooling means, for example compressed air or pre-cooled compressed air, can be introduced into the actuator chamber 58 via a cooling medium supply 81. The pressurized cooling medium can flow through the actuator chamber 58 and can escape again from the metering system 50 via a cooling medium discharge 82. When passing through the actuator chamber 58, the cooling medium flows along the outer surface of the housing 3, and heat generated during operation of the piezo actuator, which is in this case delivered to the housing surface via a potting compound with auxiliary substances in the housing 3 (FIG. 4), can be dissipated by the cooling medium. By cooperation of such cooling means 80 with the actuator module 1 according to the invention, a particularly efficient heat dissipation from the piezo actuator can be performed during operation of the metering system 50, which can have an advantageous effect on the accuracy of the metering and on the life of the piezo actuator.

[0184] A possible embodiment of an actuator module 1 with a housing 3 and a hermetically enclosed piezo actuator 2 (FIG. 3) is shown diagrammatically enlarged in FIG. 2. The housing 3 here consists of a metallic material and has a housing cover 32, a housing jacket 34 and a housing bottom 31, in which case the above-mentioned elements for forming the housing 3 are firmly connected to one another. Differently from what is shown here, the housing jacket 34 and the housing bottom 31 can also be formed in one piece in the form of a deep-drawn housing base body 31, 34.

[0185] The housing jacket 34 is formed in the manner of a metal bellows and here has a number of regularly arranged horizontal protrusions and recesses. GH or the longitudinal direction, respectively, corresponds to the longitudinal extension LE of the piezoelectric actuator 2 in the housing 3 Pa or in the longitudinal direction, respectively (Fig. 4).

[0186] 2, four different electrical terminals 21, 22 are arranged, here as contact pins 21, 22, on the housing cover 32. The respective contact pins 21, 22 are in each case routed from the outside through the housing cover 32 via different feedthroughs 33, 33' into the interior of the housing 3 in a tightly sealed and electrically insulating manner. The feedthroughs 33, 33' are realized here by glass solder and can therefore also be called glass feedthroughs 33, 33'.

[0187] A filling or loading opening 37, respectively, is further arranged in the housing cover 32, through which a free-flowing potting compound can be introduced into the housing interior space in the housing 3 to manufacture the actuator module 1. The filling opening 37 is here sealed by a pressure ball 38, for example a metal ball 38 having a diameter slightly larger than the internal cross section of the filling opening 37, so that the housing interior space in the housing 3 is sealed tight against the environment.

[0188] The housing interior space 30 of the actuator module 1 is shown, for example, in FIG. 4 and refers to the space in the housing 3 located between the piezo actuator 2, in particular the piezo actuator surface 20, and the inner surfaces 35 of the housing walls 31, 32, 34. The housing interior space 30 is substantially completely filled with the potting compound 4, in which case a small expansion area 44, for example a volume of dry gas, is arranged in the housing interior space 30. Different from what is shown in FIG. 3 and FIG. 6, preferably the expansion area 44 is not extended in the potting compound 4, for example in the direction LE. Pa or LE Gh It is possible that the potting compound 4 then reaches from the housing bottom 31 to the housing cover 32 (except for the hollow space 44). Such an extension area 44 is shown in an exemplary manner in Fig. 4. Due to the fact that the actuator modules 1 from Figs. 3 and 4 are constructed in the same way apart from the extension area 44 and differ substantially in terms of view and cross section, these actuator modules 1 will be described together. Both actuator modules 1 from Figs. 3 and 4 are illustrated quite diagrammatically and greatly enlarged.

[0189] The actuator module 1 shown in Fig. 3 includes a housing 3 having a housing cover 32, a housing jacket 34, and a housing bottom 31. Also, although not shown here, the actuator module 1 can have a deep drawn housing 3 in which the housing jacket 34 and the housing bottom 31 are integrally integrated. Other configurations of the actuator module 1 or housing 3 can exist as shown in Figs. 3 and 4.

[0190] Four electrical terminals 21, 22, each fed from the outside into the housing 3 by a glass solder feedthrough 33 (only a part of which is visible) in a tightly sealed and electrically insulating manner, are arranged in the housing cover 32. The contact pins 21, 22 are connected to actuator module control terminals 28 or temperature sensor terminals 28', respectively, which terminals 28, 28' are linked to the control means 5.

[0191] The two outer contact pins 21 here each contact a connection pole of the piezo actuator 2 in the housing interior space 30. This is particularly visible in FIG. 4, where the electrical terminals 21 contact the outer electrodes 23 as connection poles of the piezo actuator 2 here. The outer electrodes 23 are spaced apart from each other along the longitudinal extension LE of the piezo actuator 2. Pa , and via which contact with the internal electrodes 24 routed to the corresponding side of the piezo actuator surface 20. The alternating arrangement of the internal electrodes 24 in the piezo actuator 2 is shown in cross section in Fig. 3. The internal electrodes 24 are connected in parallel by an arrangement of two external electrodes 23 on two opposite sides of the piezo actuator surface 20 (only one external electrode 23 is visible in Fig. 4) and combined to form two groups, in which case the wiring of the piezo actuator 2 can be carried out by means of two electrical terminals 21 (Fig. 3).

[0192] The inner electrodes 24 are disposed between thin layers of piezo active material 25, where the piezo active material 25 is not disposed in the front region 26 of the piezo actuator 2 or in the actuator head 26 and the actuator foot 26. These regions can therefore be referred to as inactive regions 26 (FIG. 3).

[0193] Several temperature sensors 27 measure the longitudinal extension LE of the piezo actuator 2. Pa4. In addition, temperature sensors 27 are arranged in different areas of the inner face 35 of the housing 3. The temperature sensors 27 are respectively connected to two inner terminal pins 22 (FIG. 3) via terminals not shown here, the transmission of the measured values ​​to the control means 5 taking place via temperature sensor terminals 28'. These terminal pins are not shown in FIG. 4. Differently from what is shown in FIGS. 3 and 4, the temperature sensors 27 can also be arranged on the outer face 36 of the housing 3.

[0194] In Fig. 3, 4 to 7, the potting compound 4 in the housing inner space 30 comprises powdered hexagonal boron nitride (α-BN, hexagonal) as auxiliary material 40. For the sake of clarity, the auxiliary material 40 in Figs. 3 and 4 is in each case arranged only diagrammatically in the part of the housing inner space 30 which is located to the right of the piezo actuator 2, in which case in fact the entire potting compound 4 in the housing 3 comprises the auxiliary material 40. The auxiliary material 40 is present in the potting compound 4 in the form of auxiliary material platelets 40, in which case the individual auxiliary material platelets 40 are particularly adapted to the longitudinal extension LE of the piezo actuator 2. Pa The auxiliary material platelets 40 are aligned substantially in one direction with respect to the longitudinal extension LE of the piezoelectric actuator 2. Pa 4. The platelets 40 are disposed within the potting compound 4 such that a substantially uniform distribution of the auxiliary material platelets 40 along the surface of the platelets 40 is obtained (FIG. 4).

[0195] The particular alignment of the individual auxiliary material platelets 40 in the potting compound 4 is shown in Fig. 5A, in a greatly enlarged schematic cut-out of an actuator module according to the invention. The individual auxiliary material platelets 40 are aligned in such a way that they are aligned along the longitudinal extension LE of the piezo actuator 2. Pa , where each auxiliary material platelet 40 is substantially uniformly distributed along the longitudinal extension LE of the auxiliary material platelet 40. HS is the longitudinal extension LE of the piezo actuator 2 Pa, are aligned in the potting compound 4 so as to extend substantially perpendicular to the

[0196] As shown in an exemplary and entirely schematic manner in FIG. 5B, the longitudinal extension LE HS is defined as the longitudinal extension of the auxiliary material platelet 40 in a certain direction (here in the x-plane), where the maximum extension of the auxiliary material platelet 40 in the z-plane is here the width B HS Due to the elongation of the auxiliary material platelet 40 in the x-plane and in the z-plane, two base surfaces 41 are formed, where the height H HS is relatively small. In practice, the outer contour of the auxiliary material platelet can be irregular and, unlike what is shown here, the two base surfaces 41 do not have to be strictly parallel planes.

[0197] This type of auxiliary material platelets 40 are arranged in a substantially unidirectional manner in the potting compound 4 such that substantially the same density of auxiliary material platelets 40 is present in the potting compound 4 in all areas of the housing interior space 30, in particular in the area between the piezo actuator surface 20 and the inner surface 35 of the housing 3. It is shown in the schematic illustration in FIG. 5A that a part of the auxiliary material platelets 40 is directly adjacent to the piezo actuator surface 20, for example in direct contact with it. This is on the one hand an advantage, since, as a dry lubricant, the hexagonal boron nitride 40 (as the auxiliary material 40) provides a sliding attachment of the piezo actuator 2 during operation. The resulting lost heat can be further dissipated particularly effectively from the piezo actuator surface 20 by direct contact. During operation, the heat output from the piezo actuator surface 20 generally occurs mainly laterally, for example in the heat conduction direction WL.

[0198] The auxiliary material platelets 40 are arranged in one direction and substantially perpendicular to the piezo actuator face 20 such that at least the majority of the auxiliary material platelets 40 in the potting compound 4 are in contact with at least one other auxiliary material platelet 40 via contact points 45. As shown in FIG. 5A, a coherent bridge of auxiliary material 40 can be formed by such contact points 45, i.e. as directly as possible from the piezo actuator face 20 to the inner face 35 of the housing 3. Advantageously, a heat conduction path WLP for heat dissipation can be formed along such a bridge. The direction of extension of each heat conduction path WLP substantially corresponds to the heat conduction direction WL of the piezo actuator 2 given during operation.

[0199] Due to the particular design and alignment of the auxiliary material platelets 40 in the potting compound 4, the heat loss from the piezo actuator 2 can be dissipated systematically and by the shortest possible route to the inner surface 35 of the housing 3, in particular to the housing jacket 34 during operation. Due to the shape and alignment of the auxiliary material platelets 40, the number of contact points 45 can furthermore be as small as possible, which can improve the thermal conductivity or the efficiency of the thermal conduction paths WLP, respectively, along the above-mentioned bridges of the auxiliary material platelets 40. Unlike the one shown in FIG. 5A, a plurality of such thermal conduction paths WLP are usually provided through the potting compound, in particular along the longitudinal extension LE of the piezo actuator 2. Pa Extend so as to be substantially evenly distributed along the

[0200] An actuator module 1 is shown diagrammatically and greatly enlarged in Fig. 6 in a manufacturing method according to the invention. The actuator module 1 comprises a housing 3 with a housing cover 32, a housing jacket 34 and a housing bottom 31, these elements 32, 34, 31 being rigidly connected to one another. Differently from what is shown here, the housing jacket 34 and the housing bottom 31 can also be formed by deep-drawing the housing 3.

[0201] A not yet sealed filling opening 37 for the potting compound 4 is arranged in the housing cover 32, in which case the potting compound 4 is already arranged in the housing interior space 30 at the method stage shown here. A part of the housing interior space 30 does not contain any potting compound 4 and forms an extension area 44 in the hardened state of the potting compound 4, in which case, unlike what is shown here, the extension area 44 is preferably an elongated hollow space. Further components of the housing 3, for example electrical terminals, are not shown here and can be realized in the same way as in FIG. 3.

[0202] The housing 3 is located in a pressure chamber 6, in which a dry gas or silicone oil is arranged under high pressure p inside the pressure chamber 6, for example pure dry argon at a pressure of about 300 bar. Unlike what is shown here diagrammatically, the pressure p acts in the entire pressure chamber 6 and not only in the direction indicated by the arrow. The high pressure p can act on the potting compound 4 in the housing inner space 30 via the filling opening 37, and in particular on the auxiliary material platelets 40 located in the potting compound 4.

[0203] In FIG. 6, the individual auxiliary material platelets 40 are not yet arranged in one direction in the potting compound 4, but rather randomly or chaotically. For clarity, the auxiliary material platelets 40 are only diagrammatically arranged here (and in FIG. 7) in a part of the housing interior space 30 located to the right or above the piezo actuator 2, respectively, but in reality the entire potting compound 4 in the housing 3 contains the auxiliary material 40. For example, as shown in FIG. 5A, a gas under pressure p, or silicone oil, can be applied to the unsealed housing 3 for, for example, 10 minutes, to substantially perfectly unidirectionally align the auxiliary material platelets 40 with their longitudinal extension transverse to the longitudinal extension of the piezo actuator 2. The filling opening 37 can subsequently be tightly sealed by a pressing ball 38 (FIG. 2).

[0204] An actuator module 1 in a manufacturing method according to the invention is shown diagrammatically and greatly enlarged in Fig. 7. The actuator module 1 comprises a housing 3 which is arranged in a centrifuge beaker 7 of a centrifuge not shown in more detail, whereby the centrifuge beaker 7 is mounted rotatably according to a rotation direction SR.

[0205] The potting compound 4 with the auxiliary material platelets 40 is already arranged in the housing interior space 30, with the individual auxiliary material platelets 40 already arranged mainly in one direction. The housing cover 32 comprises a filling opening 37 to which a potting storage container 43 is connected. The potting storage container 43 here enters the housing interior space 30 via an injection needle 42. The injection needle 42 is arranged so as to be sealed in the filling opening 37.

[0206] Further components of the housing cover 32 are not shown here and can be realised, for example, in a similar manner to FIG.

[0207] In Fig. 7, the entire housing interior space 30 is substantially already completely filled with potting compound 4. Preferably, at the end of the centrifugation, the potting compound 4 can still remain in the potting storage container 43, which is shown diagrammatically in Fig. 7. For example, the mass percentage of the auxiliary material platelets 40 in the potting compound 4 in the housing 3 can thereby be increased, since the auxiliary material platelets 40 preferably enter the housing 3 as a result of the centrifugation. In this case, the remaining potting compound 4, in particular the base component of the potting compound, such as, for example, silicone gel, then remains mainly outside the housing 3. For example, excess potting compound 4 can be arranged in a visibly layered manner in a transparent potting storage container 43, and can be particularly separated by boron nitride 40 (as auxiliary material 40) and silicone gel that are optionally still present, with the boron nitride 40 being arranged primarily in the area of ​​the injection needle 42 and here in the right-hand part of the potting storage container 43.

[0208] The part of the method shown in FIG. 7 shows centrifugation at a target speed. In the area of ​​the housing bottom 31, the centrifuge beaker 7 is subjected to a centrifugal force F Zf is the longitudinal extension LE of the housing 3 Gh or substantially parallel to the longitudinal extension LE of the piezo actuator 2 Pa The centrifugal force F Zf is the longitudinal extension LE of the auxiliary material platelet 40 HS In particular, the centrifugal force F Zf acts substantially perpendicularly on the base surface 41 (FIG. 5B) of the auxiliary material platelet 40.

[0209] Longitudinal extension LE of auxiliary material platelet 40 HSis mainly parallel here to the rotation axis R of the centrifuge. The potting compound 4 can be introduced into the housing 3 by the method shown in Fig. 7 in cross section in an exemplary manner, whereby alignment of the auxiliary material platelets 40 takes place in the potting compound 4 in the same way as, for example, shown in more detail in Fig. 5A.

[0210] At the end of the centrifugation, preferably the injection needle 42 can be removed from the housing 3, in which case a thin, small rod can then optionally be inserted into the filling opening 37 up to the housing bottom 31, thereby forming an expansion area in the solidifying potting compound 4.

[0211] Finally, it is pointed out once again that the actuator modules detailed above are merely exemplary embodiments and can be modified in a wide variety of ways by those skilled in the art without departing from the scope of the invention. For example, a sealable housing manufactured by deep drawing can be used in this way in the respective exemplary embodiments. Furthermore, the use of the indefinite article "ein" or "eine" does not exclude that the respective feature can also be present several times. [Explanation of symbols]

[0212] 1 Actuator Module 2 Piezo actuators / components 3. Chassis 4. Potting Compound 5. Control Means 5' Connection cable 6. Pressure Chamber 7 Centrifuge Beaker 20 Piezo Actuator Surface 21 Contact pin (piezo actuator) 22 Contact pin (temperature sensor) 23 Outer electrode 24 Inner electrode 25 Piezo Active Materials 26 Inactive area 27 Temperature Sensor 28 Actuator module control terminal 28' Temperature sensor terminal 30. Internal space of the housing 31 Bottom of the case 32 Case cover 33, 33' Feedthrough / Glass Feedthrough 34 Case jacket 35 Inner surface 36 Outer Surface 37 Filling aperture / loading aperture 38 Pressing Ball 40 Auxiliary Material / Auxiliary Material Platelet / Boron Nitride 41 Base Surface 42 Injection Needle 43 Potting Storage Container 44 Expansion Area 45 contact points 50 Weighing System 51 Actuator Assembly 52 Fluid Assembly 53 Discharge element / tappet 54 Nozzle 55 Nozzle opening 56 Supply Channel 57 Housing Block 58 Actuator Chamber 58' Support element 59 Action Chamber 60 Lever 61 Aperture 62 Screw 63 Operating mechanism 64 Pressure Piece 65 Lever bearing 66 Contact surface (lever) 67 Contact surface (tappet head) 68 Tappet Head 69 Tappet spring 70 Actuator Spring 71 Tappet bearing 72 Tappet seal 73 Tappet tip 74 Encapsulating sheet 75 Nozzle Chamber 76 Metered substance storage vessel 77 Heating means 78 Heating connection cable 80 Cooling means 81 Cooling medium supply section 82 Coolant discharge part AR discharge direction B HS Width auxiliary material platelet F Zf Centrifugal force H HS Height auxiliary material platelet K Tilt axis LE Gh Longitudinal extension housing LE HS Platelets as auxiliary material for longitudinal elongation LE Pa Longitudinal extension piezo actuator p Pressure R rotation axis SR Rotation direction WL Heat conduction direction WLP Thermal Path

Claims

1. An actuator module (1), The actuator module (1) has a sealed housing (3), the sealed housing (3) having at least one piezo actuator (2) disposed therein and electrical terminals (21, 22) for at least the piezo actuator (2), the terminals (21, 22) penetrating housing walls (31, 32, 34); an internal housing space (30) between the piezoelectric actuator (2) and the housing walls (31, 32, 34) containing a potting compound (4) that electrically insulates the housing walls (31, 32, 34) from the piezoelectric actuator (2); The potting compound (4) is solid and contains at least one particulate thermally conductive and insulating auxiliary material (40); the auxiliary material (40) is arranged in the potting compound (4) so ​​that heat dissipation from the piezo actuator (2) to the housing wall (31, 32, 34) occurs during operation via the potting compound (4), in particular via the auxiliary material (40); Actuator module (1).

2. 2. The actuator module of claim 1, wherein the thermal conductivity of the auxiliary material (40) is at least about 2.5 W / (m·K), preferably at least about 30 W / (m·K), preferably at least about 50 W / (m·K), more preferably at least about 100 W / (m·K), more preferably at least about 200 W / (m·K), particularly preferably at least about 300 W / (m·K), in particular at least about 400 W / (m·K).

3. the auxiliary material (40) is present in the potting compound (4) in the form of platelets (40), and / or The auxiliary material (40) is at least partially, in particular substantially completely, within the potting compound (4) such that the longitudinal extension (LE) of each platelet (40) of the auxiliary material (40) is HS ) is the longitudinal extension (LE) of the piezo actuator (2) Pa ), preferably in the direction transverse to said elongation (LE Pa ) and are arranged to extend substantially perpendicular to the An actuator module (1) according to claim 1.

4. the auxiliary material (40) is boron nitride (40), in particular hexagonal boron nitride (40); and / or the size of the platelets (40) of said auxiliary material (40) is at least about 10 μm, preferably at least about 20 μm, preferably at least about 30 μm, and / or at most about 100 μm, preferably at most about 80 μm, preferably at most about 60 μm; and / or The auxiliary material (40) comprises a mixture of particles, in particular platelets (40), having different average sizes, The actuator module according to claim 1 .

5. 2. The actuator module of claim 1, wherein the potting compound (4) comprises a silicone gel comprising at least one base silicone and at least one cross-linking agent.

6. 2. The actuator module according to claim 1, wherein the proportion of the auxiliary material (40), in particular hexagonal boron nitride (40), in the potting compound (4) in the housing (3) is at least about 50 weight percent, preferably at least about 60 weight percent, preferably at least about 65 weight percent, in particular at least about 70 weight percent.

7. A method for manufacturing an actuator module (1) having a sealed housing (3) and at least one piezo actuator (2) arranged in said housing (3), in particular for manufacturing an actuator module (1) according to any one of claims 1 to 6, comprising at least providing electrical terminals (21, 22) for at least one piezo actuator (2) in a sealable housing (3), said terminals (21, 22) penetrating the housing wall (31, 32, 34); introducing at least one piezo actuator (2) into the housing interior space (30) of said housing (3); Optionally cleaning at least a portion of the piezo actuator (2) and / or at least a portion of the inner surface (35) of the housing wall (31, 32, 34) with plasma; providing a potting compound (4), preferably in a cured state, that electrically insulates the housing walls (31, 32, 34) from the piezo actuator (2); introducing, preferably via a fill opening (37) in the housing (3), the potting compound (4), preferably free-flowing, into the housing interior space (30) between the piezoelectric actuator (2) and the housing wall (31, 32, 34), the potting compound (4) being solid, in particular after solidification within the housing (3), and comprising at least one particulate, thermally conductive, insulating auxiliary substance (40), the auxiliary substance (40) being arranged within the potting compound (4) in such a way that heat dissipation from the piezoelectric actuator (2) to the housing wall (31, 32, 34) occurs via the potting compound (4), in particular via the auxiliary substance (40), during operation; and Sealing the housing (3). A method having the following.

8. A free-flowing potting compound (4) is provided such that the potting compound (4) to be introduced into the housing (3) comprises a silicone gel consisting of at least one base silicone and a cross-linking agent; and / or A first half of the auxiliary material (40) is mixed with at least a portion of the base silicone, and a second half of the auxiliary material (40) is mixed with at least a portion of the cross-linking agent to provide a free-flowing potting compound (4), and the mixtures thus obtained are mixed together to produce the potting compound (4) to be introduced into the housing (3). The method of claim 7.

9. A free-flowing potting compound (4) is produced such that the respective portions of base silicone and / or crosslinker in said potting compound (4) prior to introducing said potting compound (4) into said housing (3) are at least about 10 weight percent, preferably at least about 20 weight percent, preferably at least about 25 weight percent, in particular at least about 30 weight percent; and / or The free-flowing potting compound (4) is produced such that the proportion of auxiliary material (40), in particular hexagonal boron nitride (40), in the potting compound (4) before introducing the potting compound (4) into the housing (3) is at least about 10 weight percent, preferably at least about 20 weight percent, preferably at least about 25 weight percent, particularly preferably at least about 30 weight percent, in particular at least about 35 weight percent, and / or at most about 50 weight percent, preferably at most about 40 weight percent. The method of claim 7.

10. The auxiliary material (40), in particular hexagonal boron nitride (40), in the form of platelets (40) is placed in the free-flowing potting compound (4); and a pressure medium is applied to the potting compound (4) in the housing (3) for a specific time, preferably at a pressure (p) of at least about 100 bar, preferably at least about 200 bar, particularly preferably at least about 300 bar or more; The method of claim 7.

11. The auxiliary material (40), in particular hexagonal boron nitride (40), in the form of platelets (40) is placed in the free-flowing potting compound (4); and The potting compound (4) in the housing (3) is resistant to a specific inertial force (F Zf ), especially centrifugal force (F Zf ) exposed to The method of claim 7.

12. The auxiliary material (40), in particular hexagonal boron nitride (40), in the form of platelets (40) is placed in the free-flowing potting compound (4); and The potting compound (4) is configured to withstand a specific inertial force (F Zf ), especially centrifugal force (F Zf ) into the housing (3), The method of claim 7.

13. The inertial force (F Zf ) is substantially the longitudinal extension (LE) of said housing (3). Gh ) preferably in the direction of longitudinal extension (LE) of said piezo actuator (2). Pa ) on the potting compound (4), in particular on the auxiliary material (40) within the potting compound (4), The method of claim 11.

14. A metering system (50) for measuring substances, comprising: The metering system (50) comprises a nozzle (54) for outputting a metered substance, a supply channel (56) for the metered substance, a discharge element (53), and an actuator module (1) according to any one of claims 1 to 6, which is connected to the discharge element (53) and / or the nozzle (54). A weighing system (50).

15. A sealed enclosure (3), The sealed housing (3) has at least one component (2), preferably a piezo actuator (2), disposed within the housing (3), and electrical terminals (21, 22) for at least the component (2), the terminals (21, 22) penetrating the housing walls (31, 32, 34); The housing (3) comprises a housing base body (31, 34) and a housing cover (32) formed integrally therewith, and the housing base body (31, 34) can be obtained by deep drawing. A sealed enclosure (3).

16. Use of an actuator module (1) according to any one of claims 1 to 6 in a metering system (50) having at least one supply channel (56) for a metered substance, a nozzle (54) for outputting the metered substance, and a discharge element (53), the actuator module (1) cooperates with the discharge element (53) and / or the nozzle (54) to output a metered substance during operation; Use of the actuator module (1).

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