Actuator module with a hermetically sealed housing

Abstract

The invention relates to an actuator module (1) with a hermetically sealed housing (3) with at least one piezo actuator (2) arranged in the housing (3) and with electrical terminals (21, 22) at least for the piezo actuator (2). The terminals (21, 22) are led through a housing wall (31, 32, 34), wherein a housing interior space (30) between the piezo actuator (2) and the housing wall (31, 32, 34) contains a potting compound (4), which electrically insulates the housing wall (31, 32, 34) from the piezo actuator (2). The potting compound (4) is a solid and comprises at least one particulate, heat-conducting, dielectric auxiliary additive (40), wherein the auxiliary additive (40) is arranged in the potting compound (4) such that heat dissipation from the piezo actuator (2) to the housing wall (31, 32, 34) takes place during operation by way of the potting compound (4), in particular by way of the auxiliary additive (40).

Description

[0001] Actuator module with a hermetically sealed housing

[0002] The invention relates to an actuator module with a hermetically sealed housing with at least one piezo actuator arranged in the housing and with electrical connections at least for the piezo actuator, a dosing system with such an actuator module, a method for producing such an actuator module, a use of such an actuator module in a dosing system and a hermetically sealed housing.

[0003] Piezoceramic multilayer actuators, or piezo actuators for short, consist of a multitude of stacked thin layers of a piezoelectric material, e.g., lead zirconate titanate. In such multilayer piezo actuators (also called "multilayer elements," "piezo stacks," or "piezo stacks"), cascading occurs by assembling several thin piezo elements with internal electrodes in between. The internal electrodes are alternately applied to a surface of the piezo actuator, with two external electrodes connecting the respective internal electrodes. The internal electrodes are electrically connected in parallel and combined into two groups, which form the terminals of the piezo actuator. When an electrical voltage is applied to the terminals, this voltage is transferred in parallel to the internal electrodes, thereby creating an electric field in the layers of the piezoelectric material.The sum of the mechanical deformations of the individual layers of the piezoelectric material results in the usable strain and / or force of the piezo actuator.

[0004] Piezo actuators are used in a variety of technical fields, for example, in actuators and positioning drives or in dosing systems for the targeted dosing of liquid to viscous dosing materials, particularly in so-called jet valves. Particular advantages of piezo actuators include their high rigidity and pressure resistance, their high position resolution, their fast response, their ability to achieve high accelerations, and their essentially wear-free operation.

[0005] Despite these advantages, the reliability of piezo actuators has often proven inadequate in the past. Due to the high electric field strength applied to a surface of the piezo actuator during operation, polar molecules, such as water molecules, are attracted from the air surrounding the actuator. The accumulation of water molecules leads to increased conductivity on the surface of the piezo actuator and to rising leakage current. This can result in a short circuit in the layers of the piezoelectric material, which adversely affects the service life of the piezo actuator.

[0006] Piezo actuators are known in which the piezoelectric material is coated, for example, with a ceramic or glass coating. However, microcracks often form during operation of the piezo actuator, allowing water molecules to pass through the coating. Piezo actuators are also known that are housed in a metal sleeve or metal housing. Such piezo actuators often have the problem that even small amounts of water molecules in the housing, e.g., as a result of manufacturing, can be sufficient to trigger the adverse effect described.

[0007] There are also piezo actuators that are tightly enclosed in a metal housing, where a water-absorbing medium, such as a substance that chemically converts and / or binds water molecules, can be arranged within the housing. A disadvantage of such piezo actuators can be that their production is comparatively complex due to a complex manufacturing process and the chemicals used.

[0008] A further disadvantage of piezo actuators that are tightly enclosed in a metal housing—with or without a water-absorbing medium—can arise from the fact that heat dissipation from the surface of the piezo actuator is limited during operation due to the metal housing and / or a (water-absorbing) medium within the housing. The temperature of a piezo actuator can affect its geometry, particularly its longitudinal extension in a (non-switched) idle state.

[0009] As a result of thermally induced expansion, particularly due to insufficient heat dissipation from the piezo actuator during operation, the longitudinal expansion of the piezo actuator caused by the wiring of the piezo actuator and / or a generated force and / or a position of the piezo actuator within a machine may deviate from a specific target value. Since particularly high precision in the operation of the piezo actuator is required in many applications, temperature-induced changes in the length of a piezo actuator should be avoided wherever possible. Consequently, known piezo actuators with a tightly sealed metal housing and / or with a specific medium, e.g., a water-absorbing medium, in the housing can only be used to a limited extent in many technical fields.Especially for the jet valves mentioned above, which currently typically operate at high clock frequencies of up to 1 kHz, whereby a correspondingly large amount of heat is lost in the piezo actuator, an actuator module is desirable that enables sufficient heat dissipation from the surface of the piezo actuator and at the same time effectively shields the piezo actuator from damaging environmental conditions for reliable operation.

[0010] It is an object of the present invention to provide an actuator module with a hermetically sealed housing, a dosing system with such an actuator module and a method for producing an actuator module and a housing with which the disadvantages described above can be avoided or at least reduced.

[0011] This object is achieved by an actuator module according to patent claim 1 and a manufacturing method according to patent claim 7 as well as by a dosing system according to patent claim 14 and by a housing according to patent claim 15 as well as by a use of an actuator module according to patent claim 16.

[0012] An actuator module according to the invention comprises a hermetically sealed, in particular internally sealed, housing. At least one piezo actuator is arranged inside the housing. The piezo actuator can, in particular, be a piezoceramic multilayer actuator. The actuator module has at least two electrical connections, at least for the piezo actuator. The electrical connections are routed through a housing wall, in particular hermetically sealed and electrically insulated.

[0013] In the context of the invention, the term "hermetically" sealed is understood to mean that the housing is designed in such a way that no substances can pass through the housing or no substances can pass through the sealed housing. The housing is "hermetically" sealed in such a way that no solids and / or liquids and / or gases can enter the housing from the outside during operation of the actuator module. The housing preferably forms an "absolutely sealed" closure or enclosure of the piezo actuator from the environment of the housing. An "absolutely sealed" housing is understood to mean that, in particular, an exchange of air and / or water molecules via the housing is prevented. Accordingly, the housing can be "absolutely sealed" for a certain operating time, at least (relatively) with regard to air and / or water molecules, in particular to prevent long-term diffusion of water molecules through the materials of the housing during operation.The tightness of the housing can be tested, for example, using a helium leak test. The housing can, in particular, be a deep-drawn housing, as described later.

[0014] According to the invention, a potting compound is arranged in a housing interior space between the piezo actuator and the housing wall, which potting compound electrically insulates the housing wall from the piezo actuator, in particular during operation of the piezo actuator.

[0015] The potting compound is a solid, in particular an elastic solid, and comprises at least one particulate, heat-conducting, and dielectric auxiliary material. In particular, the auxiliary material itself is a dielectric. The auxiliary material is particulate, meaning it is present in the potting compound as a solid. The auxiliary material can also be referred to as a functional material.

[0016] According to the invention, the auxiliary substance is arranged in the potting compound in the housing such that heat is dissipated from the piezo actuator to the housing wall via the potting compound, in particular via the auxiliary substance in the potting compound, during operation of the actuator module. The auxiliary substance is preferably arranged in the potting compound such that heat is dissipated from a surface of the piezo actuator essentially uniformly along an entire longitudinal extent of the piezo actuator, in particular in a lateral direction. Preferably, the heat dissipated by the piezo actuator can be largely transferred via the potting compound to a housing shell of a housing wall, as will be described later. The heat dissipated by the piezo actuator can in particular be waste heat that arises during operation of the piezo actuator.

[0017] Advantageously, the actuator module according to the invention can improve the reliability of a piezo actuator, since the piezo actuator is effectively protected against harmful environmental influences, particularly against (atmospheric) humidity, during operation by the hermetically sealed housing. Furthermore, the combination of a solid, elastic potting compound with a heat-conducting, dielectric auxiliary material arranged therein according to the invention allows for particularly efficient heat dissipation from the piezo actuator, reliably protecting the piezo actuator from overheating. This can have a beneficial effect on the service life of the piezo actuator itself, so that it or the actuator module needs to be replaced less frequently.On the other hand, the actuator module can achieve particularly high dosing precision in dosing systems, as thermally induced expansion of the piezo actuator is largely prevented. The efficiency of a dosing system can also be improved, as the piezo actuator is protected from overheating even during continuous operation, so that interruptions in dosing due to a critical piezo actuator temperature can be avoided.

[0018] Furthermore, the actuator module according to the invention is also advantageously suitable for applications in which particularly high clock frequencies of a piezo actuator are required, since the potting compound and the added auxiliary material enable particularly efficient dissipation of waste heat from a piezo actuator surface to a housing wall and, via this, release of the heat to the environment. The actuator module can therefore advantageously be used in jet valves with a very high clock frequency of, for example, up to 2 kHz, which corresponds to at least twice the clock frequency compared to conventional jet valves and which is not easily possible with known actuator modules. Furthermore, the actuator module could also be profitably used in jet valves that operate at clock frequencies of 3 kHz or 4 kHz.

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

[0020] In one step, a hermetically sealable housing is provided, wherein the housing has electrical connections for at least one piezo actuator. When the housing is closed, the connections are routed through a housing wall of the housing, in particular hermetically sealed and electrically insulated. Providing the housing may involve passing the electrical connections through the housing wall. However, it is also possible for a housing with the electrical connections passed through it to be used in the process. The housing may, in particular, be a deep-drawn housing.

[0021] In a further step, at least one piezo actuator is inserted into a housing interior. Preferably, before the piezo actuator is inserted into the housing, the electrical connections of the housing are brought into operative contact with the associated connection points or connection terminals of the piezo actuator. For example, the electrical connections can be passed through a housing cover, whereby the electrical connections are connected to the connection terminals of the piezo actuator before the piezo actuator is inserted into the housing interior and / or whereby the piezo actuator is fixed to the housing cover.

[0022] In an optional step, at least a portion of the piezo actuator, in particular at least a portion of a surface of the piezo actuator, can be cleaned using a plasma. Preferably, substantially the entire surface of the piezo actuator facing the housing wall can be cleaned using plasma cleaning. Preferably, an (outer) surface of the piezoceramic material of the piezo actuator facing the housing interior and / or the connection poles of the piezo actuator can be cleaned using plasma, in particular a surface of the piezo actuator between the connection poles.

[0023] Alternatively or additionally, at least part of an inner side of the housing wall can optionally be cleaned using a plasma. The inner side of the housing wall is the area of ​​the housing wall that faces the housing interior, in particular the piezo actuator in the housing. Accordingly, the (inner) housing wall facing the housing interior can be cleaned at least in sections using plasma cleaning. Preferably, substantially the entire housing wall facing the housing interior, in particular substantially the entire inner side of the housing wall, can be cleaned using a plasma.

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

[0025] In a further step, the preferably flowable potting compound is introduced into the housing interior between the piezo actuator and the housing wall. The potting compound can preferably be introduced into the housing interior via a filling opening in the housing, in particular in a housing cover.

[0026] The potting compound is a solid, preferably an elastic solid, particularly after hardening or curing in the housing interior, and comprises at least one particulate, heat-conducting, and dielectric auxiliary material. The auxiliary material is arranged in the potting compound in such a way that heat is dissipated from the piezo actuator, particularly from a piezo actuator surface, to the housing wall during operation of the actuator module via the potting compound, particularly via the auxiliary material in the potting compound.

[0027] In a further step, the housing is hermetically sealed to form the actuator module. For this purpose, the filler opening can preferably be sealed by pressing in a press ball that has a larger diameter than the filler opening.

[0028] It should be noted that the procedural steps do not necessarily have to be performed in the described order. It would also be possible for two procedural steps to be combined into one step or to be performed essentially simultaneously.

[0029] Advantageously, the process can be used to produce actuator modules that are particularly suitable for use in dosing systems, such as jet valves. Such actuator modules for dosing systems must often meet particularly stringent quality requirements, particularly with regard to shielding the piezo actuator against moisture and piezo actuator temperature during operation. These requirements can be met by the manufacturing process according to the invention and the actuator modules obtainable thereby.

[0030] A dosing system according to the invention for a dosing substance comprises a nozzle for dispensing dosing substance, a feed channel for dosing substance to the nozzle, a preferably movably mounted ejection element, and an actuator module according to the invention coupled to the ejection element and / or the nozzle, having a hermetically sealed housing and at least one piezo actuator arranged in the housing. The dosing system may comprise further components, as described later.

[0031] Advantageously, the actuator module according to the invention can be used particularly profitably in a dosing system, in particular in a jet valve, as described above. In particular, using the actuator module can significantly increase the clock frequency for dosing substance dispensing compared to known dosing systems with conventional encapsulated piezo actuators.

[0032] The invention further relates to a hermetically sealed housing with at least one component, preferably a piezoelectric actuator, arranged in the housing. The housing comprises at least two electrical connections, at least for the component, in particular for controlling the piezoelectric actuator. The connections are routed through a housing wall of the housing, in particular in a hermetically sealed and electrically insulated manner. The housing has a one-piece housing base body and a housing cover connected thereto, in particular in a hermetically sealed manner.

[0033] According to the invention, the housing base body is obtainable by deep drawing, in particular by deep drawing a sheet metal blank. This means that the housing base body is a deep-drawn part. The housing base body is formed in one piece or in one piece and comprises a preferably tubular housing shell and a housing base, wherein the housing base closes off or delimits the housing shell on one (end) side. The housing base can in principle also be referred to as a housing cover, depending on the design of the housing and / or the arrangement of the component, e.g. the piezo actuator, in the housing. Accordingly, the housing base body according to the invention is defined in that the housing base body is formed in one piece and comprises at least one housing shell and a one-sided boundary of the housing shell firmly connected thereto, e.g. similar to a deep-drawn pot.In the description it is assumed, without limitation, that the housing base comprises a housing shell and a housing base connected in one piece thereto.

[0034] Advantageously, the mass of the housing base produced by deep drawing can be significantly reduced compared to conventional housings with a separate housing base, which is subsequently welded to a housing shell, for example. Because the housing base, which is actively moved by the piezo actuator, has a comparatively low mass, the effective stroke of the piezo actuator can be significantly increased compared to conventionally encapsulated piezo actuators. Since only one element needs to be connected to the housing base, e.g., a housing cover, the housing's manufacture is less complex with regard to achieving hermetic sealing.

[0035] Due to the low moving mass of the housing base, the housing is also suitable for dosing systems with particularly high clock frequencies, in particular jet valves. Accordingly, the deep-drawn housing can be used particularly advantageously as part of an actuator module according to the invention because the advantageous effects of the housing can thereby be synergistically complemented by the advantages of the special actuator module, in particular at high clock frequencies. The invention further relates to the use of an actuator module with a hermetically sealed housing and at least one piezo actuator arranged in the housing, in particular an actuator module according to the invention, in a dosing system with at least one feed channel for dosing substance, a nozzle for dispensing dosing substance, and a preferably movably mounted ejection element, wherein the actuator module interacts with or is coupled to the ejection element and / or the nozzle during operation for dispensing dosing substance.

[0036] Further, particularly advantageous embodiments and developments of the invention emerge from the dependent claims and the following description, wherein the independent claims of one claim category can also be developed analogously to the dependent claims and embodiments of another claim category and, in particular, individual features of different embodiments or variants can be combined to form new embodiments or variants.

[0037] The housing is designed in such a way that the entire piezo actuator is completely arranged in the housing. In particular, the piezo actuator is hermetically encapsulated in the housing. This distinguishes the housing from known enclosures such as metal sleeves, which are simply pushed onto a piezo actuator, with individual piezo actuator regions, such as an actuator base, protruding from the sleeve. Such sleeves are therefore not a “hermetically” sealed housing within the meaning of the invention. It would also be possible in principle for two or more piezo actuators to be hermetically enclosed in the same housing. For example, two separately controllable piezo actuators could be arranged essentially parallel to one another in the same housing, in which case the housing interior between the respective piezo actuators and the housing wall and / or between the two piezo actuators can contain the potting compound.The invention is described below, without limitation thereto and unless otherwise stated, using a housing with only one piezo actuator.

[0038] The housing can, as mentioned at the beginning, be a deep-drawn housing. It should be noted that a housing obtainable by deep-drawing can be used in all embodiments or further developments of the invention. This means that, in the context of the description, a "housing" is to be understood in particular as a deep-drawn housing. The housing comprises a potting compound, which is preferably introduced into the housing in flowable form for curing or hardening in the housing. In particular, the potting compound can be poured and / or injected into the housing. Consequently, the potting compound can also be referred to as a pouring compound. The potting compound in the housing is preferably produced by introducing a flowable potting compound into the interior of the housing. In the hardened state, the potting compound preferably forms a flexible solid body in the housing, particularly during operation of the actuator module.

[0039] The potting compound in the housing comprises at least one type of thermally conductive auxiliary material. An inherent thermal conductivity of the auxiliary material, i.e. a 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), more 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 aforementioned values ​​can preferably relate to the thermal conductivity of an auxiliary material that is in the form of a solid block of material, e.g. a massive block of auxiliary material. The thermal conductivity or the thermal conductivity coefficient is understood, as is generally customary, to be a material property of the auxiliary material that determines the heat flow through a material or the auxiliary material due to thermal conduction.

[0040] The thermally conductive, dielectric auxiliary material preferably comprises a large number of individual auxiliary material particles or auxiliary material particles, in particular before being introduced into the potting compound. The auxiliary material particles can in principle also aggregate to form a plurality of particles and optionally form a coherent structure. However, it is preferred that the respective auxiliary material particles are formed separately, in particular before being introduced into the potting compound. In the description of the invention, it is assumed - without being limited thereto - that the auxiliary material used comprises a large number of auxiliary material particles, wherein at least a large part of the auxiliary material particles is formed separately, i.e. the auxiliary material particles are preferably present in isolated form. The auxiliary material can preferably inherently have a powder form, in particular before being introduced into the potting compound.

[0041] Preferably, a powder-like auxiliary material, in particular outside a potting compound, can have an (inherent) thermal conductivity of at least about 1 W / (m K), preferably at least about 2 W / (m K), more 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). The auxiliary material can preferably be in the form of platelets, also referred to as auxiliary material platelets. The auxiliary material can preferably be present in the potting compound in the housing in the form of platelets. In particular, a respective auxiliary material particle in the housing can have a predominantly platelet-like configuration. The auxiliary material can preferably be an “anisotropic” filler and / or a filler with a high aspect ratio. An aspect ratio of an auxiliary material particle can be, for example, at least about 5:1, preferably at least about 25:1, more preferably at least about 40:1.

[0042] A "platelet" is understood to be a flat element or particle that is essentially the same thickness throughout and is bounded on two opposite sides by a predominantly flat surface (base surface) that is comparatively extensive in relation to its thickness. It should be noted that a particular excipient particle can also be designed only approximately as a "platelet." Accordingly, excipient particles that have slightly different thicknesses within the same particle are also referred to as "platelets." The base surfaces can have different geometries, such as approximately elliptical or circular shapes, whereby the outer contour of a base surface can also be irregular.Accordingly, a “platelet-like” excipient particle, also referred to as an excipient platelet, is defined in particular by the fact that it has two predominantly flat base surfaces, whereby the thickness of the excipient particle (corresponds to the distance between the base surfaces) is many times smaller in relation to the extent of the base surfaces.

[0043] The auxiliary material can be arranged at least partially in the potting compound, in particular essentially all auxiliary material particles, such that a longitudinal extension of a respective platelet or auxiliary material platelet runs transversely, preferably essentially orthogonally, to a longitudinal extension of the piezo actuator in the housing. Preferably, the auxiliary material particles, in particular essentially all auxiliary material particles, can be arranged in the potting compound such that a longitudinal extension of a respective auxiliary material platelet corresponds to the shortest distance between a surface of the piezo actuator and the housing wall, in particular a defined heat dissipation area of ​​the housing.

[0044] The longitudinal extension of a piezo actuator is understood to be the largest or longest extension of the piezo actuator in one direction. The longitudinal extension of an auxiliary material plate is understood to be the largest or longest extension of the auxiliary material plate in one direction, in particular along at least one base surface of the auxiliary material plate.

[0045] Advantageously, the special arrangement of the auxiliary material platelets in the potting compound in relation to the piezo actuator can be used to achieve particularly efficient heat dissipation during operation. With piezo actuators, heat emission during operation usually occurs predominantly in a lateral or radial direction due to the layered structure. This means that heat loss is predominantly dissipated laterally from a piezo actuator surface in relation to the longitudinal extent of the piezo actuator, with hardly any heat being dissipated in the axial direction, e.g. towards an actuator base or head. With encapsulated piezo actuators, it is therefore particularly effective if at least a large part of the heat loss can be dissipated laterally or radially away from the piezo actuator via the auxiliary material platelets in the potting compound, especially since a lateral region of a piezo actuator makes up a relatively large part of the overall surface of the piezo actuator.

[0046] Advantageously, the auxiliary material platelets can be positioned in the potting compound, particularly in the immediate vicinity of a surface of the piezo actuator (piezo actuator surface) and / or the housing wall, such that the longitudinal extent of the individual auxiliary material platelets essentially corresponds to a (main) heat dissipation direction of the piezo actuator during operation. Preferably, the auxiliary material platelets can be unidirectionally aligned in the potting compound and arranged so as to be substantially evenly distributed along the longitudinal extent of the piezo actuator. The resulting heat loss can be dissipated particularly efficiently from the piezo actuator surface toward the housing wall via the heat-conducting auxiliary material and its orientation in the potting compound.In contrast, in known components with embedded auxiliary materials, it is often the case that the auxiliary material particles cannot be arranged in a specific orientation for technical reasons, which can have a detrimental effect on the thermal properties of the component.

[0047] Furthermore, particularly efficient "heat conduction paths" can be advantageously formed in the potting compound via the auxiliary material, in particular in an (entire) area between the piezo actuator surface and the housing wall, in particular between the piezo actuator surface and the housing shell. In this description, the "housing shell" refers to the part of a preferably deep-drawn housing that extends at least along the longitudinal extent of the piezo actuator, in particular the part that extends along the piezoelectric material of the piezo actuator.

[0048] Advantageously, the nature of the excipient (platelet-shaped configuration) in conjunction with the orientation of the individual excipient platelets in the potting compound (predominantly orthogonal to the longitudinal extent of the piezo actuator) can ensure that the individual excipient platelets in the potting compound are each in operative contact with at least one other excipient platelet via at least one contact point. Preferably, two excipient particles can have direct contact at a contact point.

[0049] In particular, the auxiliary material platelets can be arranged in the potting compound such that a preferably uninterrupted connection or "bridge" is formed between two or more auxiliary material particles via the respective contact points. Preferably, such a bridge of auxiliary material particles can each be designed such that a heat conduction path for lost heat between the piezo actuator surface and the housing wall, in particular the housing shell, is formed thereover, preferably without interruption. Particularly preferably, the auxiliary material platelets can be arranged in the potting compound such that a plurality of such bridges of auxiliary material particles ("auxiliary material particle bridges") are arranged, preferably predominantly in parallel, in the potting compound. Preferably, the bridges of auxiliary material particles can be arranged in the potting compound so as to be substantially uniformly distributed along the longitudinal extent of the piezo actuator.

[0050] Advantageously, such thermal conduction paths can further improve heat dissipation from the piezo actuator. Since essentially all auxiliary material plates are arranged in the potting compound so that their longitudinal extension is predominantly orthogonal to the longitudinal direction of the piezo actuator, the heat from the piezo actuator can be directed specifically to the housing shell of the housing wall, largely preventing undesirable, e.g., axial, heat conduction in the potting compound. Furthermore, the orientation of the auxiliary material plates allows the heat loss to be conducted to the housing shell via the bridge formation along the most direct and shortest possible path.

[0051] A further advantage is that the platelet-like configuration of the auxiliary material particles and their alignment within the potting compound allows for a comparatively large number of contact points to be formed between the auxiliary material particles (present in the potting compound), particularly compared to the same amount of an isotropic, e.g., spherical auxiliary material. Since a lack of (direct) contact between auxiliary material particles can adversely affect the effectiveness of thermal conduction paths, e.g., due to a potting compound with poor thermal conductivity, the amount of heat dissipated by the piezo actuator during operation (per unit of time) can be further increased by the configuration of the auxiliary material particles and their alignment within the potting compound.

[0052] The auxiliary material can preferably be boron nitride (BN). The auxiliary material can particularly preferably be hexagonal boron nitride (α-boron nitride). Hexagonal boron nitride (α-BN, hexagonal) consists of layers of a planar, hexagonal honeycomb structure in which the B and N atoms occur alternately and is, moreover, generally known. Particularly preferably, the boron nitride as an auxiliary material can be in powder form with a pronounced crystal structure before processing. In particular, the boron nitride can be in the form of platelet-shaped individual crystals before processing and / or in the hardened potting compound. Particularly preferably, each individual (BN) crystal can form one auxiliary material particle or one auxiliary material platelet.

[0053] An average size of the platelets or auxiliary material platelets, in particular an average diameter of the BN single crystals in the potting compound, can be at least about 10 pm, preferably at least about 20 pm, more preferably at least about 30 pm and / or at most about 100 pm, preferably at most about 80 pm, more preferably at most about 60 pm, in particular about 45 pm. The size or diameter of an auxiliary material platelet is generally understood to be the longest extension of an auxiliary material platelet in one direction, in particular if an auxiliary material platelet has an irregular outer contour. Preferably, an average particle size (Dso) in the potting compound can be approximately 45 pm. For example, the auxiliary material can be boron nitride of the type “CL-SP 045” (manufacturer: Henze Boron Nitride Products AG, Germany).

[0054] Advantageously, the particularly high thermal conductivity of boron nitride (e.g., up to approximately 5 W(m K) for powdered BN) can further increase heat dissipation from the piezo actuator surface. Another advantage of boron nitride over other thermally conductive materials is its high dielectric resistance and low dielectric constant, making it particularly suitable for use with encapsulated piezo actuators. Since boron nitride in the a-modification has a low density (approximately 2.25 g) compared to other thermally conductive materials, it is also suitable for use in high-temperature applications. -3), the mass fraction of boron nitride in the potting compound can be reduced compared to other thermally conductive materials, while still achieving a certain heat flow. This allows the weight of the actuator module to be reduced if necessary. Heat flow here refers to the thermal energy dissipated per unit of time from the piezo actuator surface through the entire potting compound, i.e., the thermal output.

[0055] Another advantage is that the special shape and size of the individual BN auxiliary material particles can further increase heat dissipation from the piezo actuator. This is because with increasing particle size, the number of contact points required between the individual auxiliary material particles to form heat conduction paths can be reduced, with each contact point forming a thermal resistance. Consequently, particularly efficient heat dissipation is possible with BN auxiliary material particles of a certain size, while the BN auxiliary material particles can still be arranged as desired in the potting compound. A further advantage arises from the fact that hexagonal boron nitride has the properties of a dry lubricant, with the friction coefficient remaining stable at typical operating (surface) temperatures of piezo actuators. Consequently, the piezo actuator can be slidably mounted in the potting compound via the boron nitride.

[0056] The excipient, in particular hexagonal boron nitride, can preferably comprise a mixture of (excipient) particles, preferably platelets, with at least two different average sizes. In particular, the excipient can comprise a mixture of powdered boron nitride with a first average particle size and powdered boron nitride with a different, second average particle size. The excipient provided in the form of such a mixture is also referred to as an excipient mixture.

[0057] Preferably, a mixture can be provided such that boron nitride powder with a (relatively) small average particle size is admixed with boron nitride powder with a (relatively) large average particle size. Preferably, the auxiliary agent can be a mixture of powdered boron nitride with an average particle size (Dso) of approximately 45 pm and powdered boron nitride with an average particle size (Dso) of approximately 20 pm. Preferably, boron nitride of the type “CL-SP 045” and of the type “CL-ADM 020” can be used for the mixture (manufacturer: Henze Boron Nitride Products AG, Germany). Preferably, the powdered boron nitride with the average particle size of approximately 20 pm, e.g. type “CL-ADM 020”, has an approximately platelet-like configuration.Preferably, powdered boron nitride with an average particle size of approximately 20 μm can be admixed with powdered boron nitride with an average particle size of approximately 45 μm, so that the (admixed) proportion is at least approximately 1 wt.%, based on the total amount of the (readily mixed) excipient or excipient mixture. The (admixed) proportion can preferably be at least approximately 2 wt.%, preferably at least approximately 3 wt.%, particularly preferably at least approximately 4 wt.%. The (admixed) proportion can preferably be approximately 4.25 wt.%, in particular approximately 4.5 wt.%.

[0058] Advantageously, the use of boron nitride powder with different average particle sizes can further increase heat dissipation from the piezo actuator. For example, the (relatively) small boron nitride particles can penetrate into the spaces between the (relatively) large boron nitride particles and at least partially fill them, and / or can increase the contact area of ​​the boron nitride with the housing.

[0059] 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 hardener. Alternatively or in addition to the silicone gel, the potting compound in the housing could also comprise one or more polyurethanes. In principle, the potting compound could also be formed from other basic components.

[0060] Preferably, the potting compound in the housing is designed such that, during operation of the actuator module for a specific period of use of the actuator module, it has at least one, preferably all of the following properties (simultaneously):

[0061] - During operation, there is essentially no release of low-molecular reaction products such as H2O, NH3, CO2, acetic acid, etc. from the casting compound.

[0062] - The insulation resistance of the basic components of the casting compound (without auxiliary material), e.g. a silicone gel, is preferably at least T10 12 D em, preferably at least T10 15 Q cm, in particular at least T10 16 Q cm or more.

[0063] - A (maximum) working temperature of the casting compound is at least 140 °C, preferably at least 160 °C, preferably at least 200 °C or more.

[0064] - The potting compound is stable against aging processes for a certain period of use, in particular by preventing the release of conductive reaction products. - The thermal conductivity of the basic components of the potting compound (without auxiliary materials), e.g., a silicone gel, is preferably at least 0.08 W / (m K), more preferably at least 0.15 W / (m K), in particular at least 0.2 W / (m K).

[0065] Preferably, the (hardened) potting compound in the housing, in particular due to the silicone gel, 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 of at most about 65.

[0066] Advantageously, the potting compound in the housing is designed as a solid body such that a specific orientation of the auxiliary material particles in the potting compound is maintained during operation of the actuator module. However, the potting compound in the housing is also designed to be flexible in order to enable an expansion movement of the piezo actuator during operation and / or to enable a (minor) deformation of the housing during operation. A further advantage of the potting compound with at least one silicone gel arises during the manufacture of the actuator module, whereby the potting compound can be introduced into the housing in flowable form via a small filling opening and then finally solidifies into a flexible solid body in the housing, as described later.

[0067] The potting compound can preferably be such that a proportion of auxiliary material, in particular hexagonal boron nitride, or a proportion of an auxiliary material mixture in the potting compound in the housing, in particular in the hardened potting compound, is at least approximately 50% by weight, preferably at least approximately 60% by weight, preferably at least approximately 65% ​​by weight, in particular at least approximately 70% by weight.

[0068] Advantageously, such a high mass fraction of hexagonal boron nitride in the potting compound can further improve heat dissipation from the piezo actuator. In particular, with a mass fraction of a-boron nitride of 50 wt.% and more, the thermal conductivity of the potting compound in the housing, i.e., including the boron nitride, can be achieved so that it approaches the thermal conductivity of the piezo actuator in the lateral direction. The thermal conductivity of the potting compound can also essentially correspond to the thermal conductivity of the piezo actuator in the lateral direction.

[0069] Accordingly, the auxiliary material, in particular boron nitride, can be arranged in the potting compound such that a thermal conductivity of the hardened potting compound in the housing is at least approximately 90%, preferably at least approximately 95%, preferably at least approximately 99%, particularly preferably approximately 100%, in particular approximately 101% or more, of a thermal conductivity of the piezo actuator, in particular a thermal conductivity of the piezo actuator in a lateral direction or in the direction of a shortest path to the housing wall. A lateral direction is understood to mean a direction substantially transverse to the longitudinal extents of the piezo actuator. For example, a lateral direction can run approximately parallel to the internal electrodes of a piezo actuator. A lateral region of a piezo actuator can preferably be a region of the piezo actuator between an actuator base and an actuator head, in particular a section with internal electrodes stacked in layers.

[0070] For example, a 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, could be approximately 2.45 W / (m K). The potting compound can then preferably be designed in such a way, in particular with regard to the nature of the boron nitride and / or the mass fraction of boron nitride and / or the orientation of the BN individual crystals in the potting compound, that a thermal conductivity of the finished potting compound, in particular in a lateral direction from a piezo actuator surface to the housing wall or to the housing shell, is at least approximately 2.45 W / (m K) or somewhat more. Advantageously, a further increase in the thermal conductivity of the finished potting compound, in particular in the lateral direction, can be achieved by mixing boron nitride powders with different average particle sizes. For example, with an admixture proportion of approximately 1.5 wt.By mixing 0.1 wt.% boron nitride with an average particle size of 20 pm to 98.5 wt.% boron nitride with an average particle size of approximately 45 pm, a thermal conductivity of the finished potting compound of more than 3.5 W / (m K) can be achieved. Furthermore, the thermal conductivity of the finished potting compound can also be 4 W / (m K) or more.

[0071] Advantageously, the heat loss generated during operation of the actuator module can be largely dissipated from the piezo actuator surface, allowing the piezo actuator to be maintained within a specific temperature range. This can be particularly advantageous for jet valves with high clock frequencies, as it prevents the risk of overheating of the piezo actuator and thus enables continuous operation.

[0072] For particularly efficient heat dissipation, the housing interior between the piezo actuator and the housing wall can be essentially completely filled with the hardened potting compound during operation. "Essentially completely" means that a certain expansion volume can be present in the housing, in particular to compensate for (necessary) thermal expansion of the piezo actuator and / or the potting compound. Such an expansion region free of potting compound could, for example, comprise a volume of an inert gas and / or be formed as an elongated cavity that runs essentially parallel to a longitudinal extension of the housing.

[0073] The housing, which hermetically encloses the piezo actuator, is preferably designed to be "fatigue-resistant." "Fatigue-resistant" or "endurance-resistant" is understood here to mean that, within the scope of a typical service life of the piezo actuator itself arranged in the housing, i.e., after a number of oscillations (deflections) which the piezo actuator can usually undergo during operation (due to its design), regardless of the encapsulation, no fatigue phenomena occur on the housing itself. Preferably, the housing is designed to form a sufficiently "durable" and continuously effective hermetic diffusion barrier so that no solids and / or liquids and / or gases can pass through the housing. Preferably, the housing is designed to be "durable" such that it remains permanently operative even after a number of at least 2.5-10 8 , particularly preferably of at least 1 ■ 10 9, cycles or deflections of the encapsulated piezo actuator is completely intact, ie in particular forms a hermetic housing for the piezo actuator.

[0074] To achieve fatigue strength, the housing can be constructed predominantly from a metallic material. Alternatively, individual areas of the housing can also be made from a different, non-metallic material. For example, a housing base and / or cover could comprise a ceramic base material or be constructed using a flexible membrane. Other materials are also conceivable, as long as they enable a sufficiently durable hermetic seal of the housing, even during operation of the actuator module.

[0075] The housing can particularly preferably be produced by deep-drawing, as described above. The material of a deep-drawn housing base body can preferably be beryllium copper and / or stainless steel and / or steel. A housing cover can preferably be made of beryllium copper and / or stainless steel and / or steel and / or copper and / or brass. In principle, a housing cover can also be made of at least one other metal or a metallic alloy. A wall thickness of a deep-drawn housing base body can, for example, be at least approximately 0.05 mm, preferably at least approximately 0.08 mm. For example, a wall thickness of a deep-drawn housing base body can be approximately 0.09 mm, preferably approximately 0.1 mm. In principle, greater wall thicknesses are also possible, e.g. 0.15 mm or more.

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

[0077] The housing base body and / or the housing cover can preferably be coated with a solder for soldering. For example, a layer of solder approximately 8 μm thick can be applied to an edge region of the housing cover to be soldered and / or to a part of the housing base body receiving the edge region before soldering. For soldering, a solder layer on the housing base body and / or on the housing cover can preferably be at least partially liquefied by means of induction. For soldering, a frequency of an induction coil can preferably be at least 20 kHz, preferably at least 50 kHz, preferably at least 100 kHz. For example, a frequency can be at most 500 kHz, preferably at most 200 kHz, preferably at most 150 kHz. In principle, however, higher frequencies can also be used for soldering, e.g. 600 kHz or more.

[0078] Advantageously, a secure, particularly hermetically sealed, connection can be formed between the housing base and the housing cover, particularly by utilizing the skin effect, whereby the temperature in the housing can be kept as low as possible to protect elements arranged therein, such as a piezo actuator. Advantageously, by utilizing the skin effect, a very short induction time, e.g., in the range of less than 500 milliseconds, allows the temperature in the housing interior and / or in the piezo actuator to be less than 200 °C.

[0079] It would also be possible in principle for a housing base, a housing shell, and a housing cover to be (initially) manufactured as separate elements and then permanently and hermetically sealed together to form the housing, e.g., by welding, flanging, soldering, pressing, etc., whereby the three elements then form a housing wall. It would also be possible in principle for two housing halves to be initially provided and then permanently and hermetically sealed together, preferably along their longitudinal extent, to form a housing. However, it is preferred for a housing to be manufactured at least partially by deep drawing, as described above.

[0080] Preferably, a housing - regardless of the specific design - can be designed, at least in sections, in the manner of a fold-like bellows, in particular a fold-like metal bellows. For example, in a deep-drawn housing, a bellows can be incorporated into the housing base body, in particular into the tubular housing shell, at least in partial areas. Such a bellows can be introduced into the housing shell (after deep-drawing), for example, by means of hydroforming. The upper end of the housing can be formed by a housing cover that is firmly connected to the housing shell and is preferably plane-parallel to the housing base. In this case, the housing base body and the housing cover then form the housing wall.

[0081] Advantageously, by at least partially designing the housing in the manner of a metallic bellows, the housing can be partially flexible, allowing the piezo actuator to expand as freely as possible within the housing when voltage is applied. A particular advantage arises in combination with a deep-drawn housing, as the rapid expansion of the piezo actuator is further facilitated by the low moving mass of the housing base.

[0082] The area of ​​the housing with a bellows can preferably form a defined heat dissipation area of ​​the housing, via which a particularly efficient heat transfer from the housing wall (housing shell) to the environment takes place during operation of the actuator module. For example, a cooling device of a higher-level machine, e.g. as part of a valve, could be assigned to the heat dissipation area during operation, with the bellows then forming "cooling fins" around which a cooling medium preferably flows. As a result, the temperature of the piezo actuator can be set to a specific target value during operation of the actuator module and, in particular, can be actively regulated. Preferably, the heat dissipation area of ​​the housing can be assigned to the lateral area of ​​a piezo actuator. Preferably, a housing can be formed at least partially, in particular substantially entirely, from one or more inorganic materials.Preferably, a housing can be constructed exclusively of inorganic materials to form a hermetically sealed housing. Hermetically sealed encapsulation of the piezo actuator can preferably also be achieved by using only inorganic materials to encapsulate the piezo actuator, in particular to form the housing. For example, the housing can be made of beryllium copper and / or stainless steel and / or steel and / or copper and / or brass and / or another metal or metallic alloy. Accordingly, the housing can be free of organic materials.

[0083] Preferably, the housing is hermetically sealed in such a way that the passage of substances, e.g., water molecules, through the housing, in particular by means of permeation, is prevented or suppressed during operation of the actuator module. Preferably, permeation can approach zero during operation of the actuator module. In other words, the housing can form a permeation barrier or permeation stop during operation, in particular for water molecules. Preferably, the housing can be permeation-tight during operation of the actuator module. Accordingly, to prevent permeation, the housing can be designed such that no substances (permeates) can penetrate or migrate through the housing during operation.

[0084] Advantageously, a housing made entirely of inorganic materials can achieve particularly reliable hermetic encapsulation of the piezo actuator and thus permanent shielding of water molecules. With other piezo actuators that have a casing made entirely or predominantly of organic materials, e.g., one based on silicone, water molecules can pass through the organic material during operation, particularly if there is a concentration gradient across the casing. The organic materials in such casings, e.g., silicone elastomers, often contain free water molecules in low concentrations. Since the water molecules are not bound in the organic material, they can move until the concentration equalizes between two sides of the organic material, e.g., between an outer and an inner side of a casing.Advantageously, the hermetically sealed housing can be designed such that the piezo actuator in the housing can be subjected to a continuous electrical current (continuous current supply) for a specific period of use of the actuator module. Advantageously, the piezo actuator can be effectively shielded from water molecules in the external environment of the housing by the hermetically sealed housing, even when an electrical field is continuously applied during operation. In other piezo actuators with an organic coating, e.g., silicone, water molecules can be transported through the coating and into the coating by the electric field generated as a result of the current supply to the piezo actuator, particularly during continuous current supply.

[0085] Preferably, the piezo actuator can be arranged inside the closed housing such that the respective ends or end regions of the piezo actuator rest directly on the housing base or the housing base and cover, particularly when the piezo actuator is in a resting, i.e., non-expanded, state. Preferably, at least one end region of the piezo actuator, e.g., an actuator head, can be firmly connected to the housing (cover).

[0086] Preferably, the housing can be designed such that a surface of the piezo actuator arranged in the housing and an inner side of the housing wall, at least in the region of the housing shell, do not directly touch each other. In other words, an inner cross-section of the housing, which runs essentially transversely to the longitudinal extent of the housing, can preferably be larger than a corresponding cross-section of the piezo actuator arranged in the housing.

[0087] To monitor a temperature, at least one temperature sensor can be arranged on an inner side of the housing wall facing the piezo actuator and / or on an outer side of the housing wall opposite the inner side and / or within the potting compound. Preferably, at least one temperature sensor, preferably two or more temperature sensors, can be arranged in different regions of the piezo actuator surface in order to detect a temperature gradient along the longitudinal extent of the piezo actuator. At least one temperature sensor could also be arranged directly in a piezo actuator core, i.e. in a central center point of a cross-sectioned piezo actuator, or in a radially spaced (edge) region of a piezo actuator. The temperature sensors are preferably coupled to electrical connections of the housing, which are guided through the housing wall in a hermetically sealed and electrically insulated manner.Outside the housing, the recorded measured values ​​can be fed, for example, to a control device assigned to the actuator module. It should be noted that, for routing through the housing wall, two or more electrical connections can be combined, at least temporarily, so that several electrical connections are routed through the housing wall via the same feedthrough. However, it is also possible for each electrical connection to be routed separately through the housing wall.

[0088] The electrical connections can preferably be implemented using electrical plugs or connection pins. Preferably, each plug is passed through the housing using a glass solder that is permanently integrated into the housing. The respective glass solders or glass feedthroughs can preferably be incorporated into the housing base (or the housing base body) and / or the housing cover. Particularly preferably, the electrical plugs or conductors are routed from the interior of the housing to the exterior using glass solder in a hermetically sealed and electrically insulated manner.

[0089] To produce an actuator module, as already described, a potting compound is provided which, preferably in the hardened state, electrically insulates a housing wall from a piezo actuator. Preferably, the potting compound itself, i.e., without the auxiliary material, is a dielectric. The potting compound is preferably arranged in the housing interior such that essentially the entire piezo actuator surface is electrically insulated from the housing wall.

[0090] In a preferred method, a flowable potting compound is produced in such a way that the potting compound to be introduced into the housing comprises a silicone gel which comprises at least a base silicone and a cross-linking agent. The base silicone can, for example, be a silicone of type SG 75L2-30, wherein a type SG 79L5-30 can be used as the cross-linker (manufacturer in each case: Elantas, Germany). As already described, a polyurethane or another suitable silicone could also be used, whereby the potting compound should preferably have the properties mentioned at the beginning. For example, depending on the production process for the actuator module, a silicone gel with a higher viscosity than the one mentioned above could also be used. Preferably, to provide or produce the flowable potting compound, a first half portion of the total auxiliary material orThe entire excipient mixture is mixed with at least a portion of a base silicone. Preferably, a second (identically large) half portion of the excipient or excipient mixture is mixed with at least a portion of the crosslinking agent. Preferably, the first half portion of the excipient can be mixed with the total amount of the base silicone intended for producing the casting compound. Similarly, the second half portion of the excipient can be mixed with the total amount of crosslinking agent.

[0091] Preferably, in a further (second) step, the respective mixtures thus obtained can be mixed with one another in order to produce the flowable potting compound to be introduced into the housing.

[0092] Preferably, the flowable potting compound can be produced such that a respective proportion of base silicone and / or crosslinking agent in the potting compound before introducing the potting compound into the housing is at least about 10 wt.%, preferably at least about 20 wt.%, preferably at least about 25 wt.%, in particular at least about 30 wt.% or more.

[0093] Preferably, the flowable potting compound can be produced such that a proportion of auxiliary material, in particular hexagonal boron nitride, or a proportion of the auxiliary material mixture in the potting compound before introduction of the potting compound into the housing is at least approximately 10 wt. %, preferably at least approximately 20 wt. %, preferably at least approximately 25 wt. %, particularly preferably at least approximately 30 wt. %, in particular at least approximately 35 wt. The potting compound is preferably produced such that the proportion of the auxiliary material or of the auxiliary material mixture in the (total) flowable potting compound is at most approximately 50 wt. %, preferably at most approximately 40 wt. The auxiliary material, in particular hexagonal boron nitride, can preferably be arranged in the form of platelets (auxiliary material platelets) in the flowable potting compound.

[0094] Advantageously, by portioning the auxiliary material for producing the potting compound and mixing it proportionally with the individual components of the potting compound to be produced, the mass fraction of auxiliary material in the finished, flowable potting compound can be set as high as possible. In particular, the mass fraction of hexagonal boron nitride can be increased compared to a process in which the same amount of substance (a-BN) is mixed with only one component of the potting compound to be produced, whereby the potting compound is still flowable and processable. “Flowable” is understood to mean a potting compound which is such that the potting compound can be introduced into a housing by means of pressure and / or by means of an inertial force, in particular a technically generated one, for the production of the actuator module, in particular via a filling opening in the housing.For example, a “flowable” potting compound may have a viscosity of not more than 1000 cSt (centistokes), preferably not more than 500 cSt.

[0095] Advantageously, a flowable potting compound allows the potting compound to be introduced into an otherwise sealed housing through a very small filling opening, e.g., one with a diameter of 1 mm or less. Furthermore, the potting compound can be distributed within the housing interior in such a way that essentially the entire surface of the piezo actuator is directly adjacent to the hardened potting compound. In particular, the flowable potting compound can flow around corners in the housing and fill small cavities.

[0096] According to one embodiment of the manufacturing method, in particular for aligning the auxiliary material particles in the potting compound, the auxiliary material or the auxiliary material mixture, preferably hexagonal boron nitride, can be arranged in the form of platelets in the flowable potting compound, wherein the not yet hardened potting compound is subjected to a pressure medium for a specific time in a (still) unsealed housing. In particular, a filling opening of the housing can still be unsealed. Preferably, the pressure can be applied from outside the housing in such a way that, as a result of the pressure application, a respective auxiliary material platelet is arranged in the flowable and / or in the curing and / or in the hardened potting compound in such a way that a longitudinal extent of a respective auxiliary material platelet runs transversely, preferably substantially orthogonally, to a longitudinal extent of the piezo actuator.

[0097] Preferably, a pressure may be at least 100 bar, preferably at least 200 bar, particularly preferably at least 300 bar or more.

[0098] The pressurization can take place for at least one minute, preferably for at least 5 minutes, more preferably for at least 10 minutes. The pressure medium can be a silicone oil. Alternatively or additionally, the pressure medium can be a dry gas and / or a dry gas mixture. The dry gas or gas mixture preferably has a moisture content of at most about 5 parts per million (ppm), preferably of at most about 3 ppm, more preferably of at most about 2 ppm, more preferably of at most about 1 ppm, most preferably of at most about 0.5 ppm.

[0099] Alternatively or additionally, the potting compound in the housing can be exposed to a pressure lower than normal pressure for a certain period of time, in particular to a vacuum. Pulsed pressure loading can preferably be carried out in such a way that the potting compound in the housing is alternately subjected to an overpressure and a normal or negative pressure, each relative to normal pressure.

[0100] Advantageously, a pulsed or multiple pressure load can contribute to ensuring that essentially all auxiliary material particles or auxiliary material platelets have a specific orientation in the hardened potting compound, especially during operation of the piezo actuator.

[0101] According to one embodiment of the manufacturing method, the excipient or excipient mixture, preferably hexagonal boron nitride, can be arranged in the form of platelets in the flowable potting compound, particularly for aligning the excipient particles in the potting compound. The potting compound can be prepared as described above. In this embodiment, the preferably not yet hardened potting compound can be subjected to a specific, particularly technically generated, inertial force in an unsealed or sealed housing.Preferably, the flowable and / or the curing and / or the hardened casting compound can be subjected to a centrifugal force, in particular a technically generated one, so that a respective auxiliary material plate is arranged in the flowable and / or the curing and / or the hardened casting compound as a result of the centrifugal force in such a way that a longitudinal extension of a respective auxiliary material plate runs transversely, preferably substantially orthogonally, to a longitudinal extension of the piezo actuator.

[0102] Particularly preferably, in this embodiment, the auxiliary material or auxiliary material mixture, in particular hexagonal boron nitride, can be arranged in the form of platelets in the flowable potting compound, wherein the potting compound is introduced into the housing itself by means of a specific, preferably technically generated, inertial force, in particular a centrifugal force, acting on the housing and / or the potting compound. The inertial force is preferably applied such that the inertial force acts essentially orthogonally on a base area of ​​the respective auxiliary material particles during introduction and / or solidification of the potting compound, in particular with respect to a spatial arrangement or orientation of the particles in the hardened potting compound.

[0103] In particular, a technically generated centrifugal force can act on the housing and / or on the potting compound in such a way that a respective auxiliary material plate is arranged as a result of the centrifugal force with respect to its longitudinal extent transversely, preferably substantially orthogonally, to a longitudinal extent of the piezo actuator in the flowable and / or in the curing and / or in the hardened potting compound.

[0104] The method can preferably be carried out such that the inertial force acts on the potting compound, in particular on the auxiliary material in the potting compound, essentially in the direction of a longitudinal extension of the housing, preferably in the direction of a longitudinal extension of the piezo actuator in the housing. Preferably, the inertial force can act on the potting compound and / or the auxiliary material predominantly orthogonal to a shortest distance between the piezo actuator and the housing wall, in particular the housing shell.

[0105] Advantageously, an inertial force can be used to both introduce the potting compound with the auxiliary material platelets into the housing and achieve a specific, advantageous orientation of the auxiliary material platelets within the potting compound. This allows the manufacturing process to be carried out particularly efficiently and achieves a specific orientation of essentially all auxiliary material particles in the (hardened) potting compound. The inertial force can preferably be a technically generated centrifugal force or a centrifugal force.

[0106] A further advantage is that in the manufacturing process, by utilizing an inertial force directed in a specific way towards the housing, the mass fraction of the auxiliary material, in particular hexagonal boron nitride, in the hardened potting compound can be significantly increased compared to other processes. Preferably, by means of the special process, a proportion of, for example, up to 70 wt.% hexagonal boron nitride can be achieved in the hardened potting compound in the housing, whereby the flowable potting compound only has, for example, a proportion of 35 wt.% hexagonal boron nitride. Advantageously, on the one hand, the mass fraction of a-BN can be adjusted so that the potting compound is just still flowable, while on the other hand, the mass fraction of a-BN in the hardened potting compound is significantly increased by the manufacturing process compared to the initial value. In this way, the thermal conductivity of the potting compound can be increased in order to achieve particularly high heat dissipation from the piezo actuator.

[0107] It is fundamentally possible to combine the two previously described embodiments. For example, a flowable potting compound can be introduced into a housing using a technically generated centrifugal force. The alignment of the auxiliary material particles in the potting compound could then be achieved, for example, by applying pressure to the potting compound in the housing. It would also be possible to introduce a flowable potting compound into a housing using centrifugal force, in which case the potting compound would be subjected to pressure and then subjected to another centrifugal force.

[0108] In the manufacturing process, regardless of the specific embodiment, it can be provided that at least the housing and / or the piezo actuator and / or the auxiliary material undergo a pretreatment before the potting compound is poured into the housing. Pretreatment can preferably involve exposing the components to a vacuum for a specific period of time and / or heating them to a specific temperature.

[0109] For heating and / or evacuation, the housing can preferably comprise a deep-drawn housing base body and a housing cover firmly connected to it, wherein a piezo actuator is arranged in the housing and wherein the connection between the housing components is such that a hermetically sealed closure of the housing can (later) be formed above it. The housing cover preferably has at least one closable (filling) opening which can be hermetically sealed to form the finished housing. Such a housing (with built-in piezo actuator) and the auxiliary material or the auxiliary material mixture are preferably exposed to a vacuum of e.g. 10 to 100 mbar, in particular outside the housing. The components are preferably heated at the same time. Accordingly, the manufacturing method can preferably include a vacuum drying process. For the vacuum drying process, the components can be arranged in a heatable vacuum vessel, e.g.B. in a vacuum chamber.

[0110] Preferably, heating is carried out to a temperature of at least 60 °C, preferably at least 90 °C, preferably at least 110 °C and / or at most 190 °C, preferably at most 150 °C, preferably at most 140 °C. The heating and / or evacuation can take place 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.

[0111] Preferably, the components are heated to a temperature of 130°C for a period of 48 hours. Particularly preferably, the components are placed in a vacuum of approximately 10 mbar during heating. Regardless of the specific heating parameters, the heating can preferably be carried out using infrared radiation.

[0112] Advantageously, this can already be achieved by ensuring that the housing interior or the components arranged inside the hermetically sealed housing to be produced are as completely free as possible from FW molecules.

[0113] Preferably, the piezo actuator can be subjected to an electrical voltage at least once or briefly during heating and / or evacuation, in particular during heating under vacuum. Preferably, the piezo actuator can be subjected to an electrical voltage several times during the vacuum drying process, in particular continuously throughout the entire duration of heating under vacuum. Preferably, the voltage can be the highest permissible voltage for the piezo actuator. This procedure can contribute to the particularly efficient and reliable removal of FW molecules from the components to be dried or to be dried, in particular a piezo actuator in the housing.

[0114] The vacuum drying process can preferably be carried out by flooding the vacuum vessel with a protective gas at least once. Preferably, the components to be dried can be exposed to a protective gas for a specific period of time, in particular for a duration of approximately 30 seconds. Preferably, a pressure of approximately 600 mbar can be generated in the vacuum vessel during the flooding with protective gas. Preferably, the original vacuum can be reapplied after the protective gas application has ended. The protective gas can be a dry inert gas, e.g., dry argon.

[0115] The vacuum drying process can preferably be carried out in such a way that the vacuum vessel is temporarily flooded with protective gas two or more times. Preferably, a vacuum can be applied again after each flooding with protective gas. The vacuum drying process can particularly preferably be carried out for a duration of 48 hours, wherein the vacuum vessel is temporarily flooded with a protective gas, in particular dry argon, at intervals of approximately two hours. Each flooding duration can be approximately 30 seconds. Advantageously, by applying protective gas to the components and subsequently evacuating them, molecules that are undesirable during operation of the piezo actuator (e.g. H2O, H, O2) can be removed particularly reliably from the components to be dried, in particular from a housing that is already partially closed.

[0116] The manufacturing method may include cleaning at least part of the piezo actuator, in particular at least part of the surface of the piezo actuator, and / or at least part of the inner housing wall by means of plasma cleaning. Plasma cleaning can preferably be carried out in a vacuum. In particular, plasma cleaning can be integrated into the described vacuum drying process. It would also be possible in principle for plasma cleaning to take place independently of the vacuum drying process. For example, plasma cleaning can then form a separate step of the manufacturing method. Regardless of the specific embodiment, plasma cleaning preferably takes place before the potting compound is poured into the housing.

[0117] Plasma cleaning is preferably carried out on a housing with a piezo actuator arranged therein. The housing is preferably already partially closed, with the housing interior being accessible from the outside via a closable (filling) opening in the housing cover. The piezo actuator can be glued at least to the housing cover, preferably also to the opposite housing base. Plasma cleaning can preferably be carried out during the described vacuum drying process. Preferably, a plasma can be generated once or several times during the vacuum drying, each time for a specific duration. It is also possible for a plasma to be generated during the entire vacuum drying process. Accordingly, the housing with the piezo actuator for plasma cleaning can be arranged in the same vacuum vessel (as a process chamber) in which the vacuum drying process is carried out, in particular at the same time.Advantageously, the generation of a plasma can be promoted by a vacuum. Furthermore, this combination of individual processes can advantageously make the method more efficient. Alternatively, the plasma cleaning could also be carried out on a housing that has previously been subjected to a vacuum drying process. The method can be carried out in such a way that the piezo actuator forms an electrical pole in the housing during plasma cleaning. Preferably, the two electrical connections or connection poles of the piezo actuator can be supplied with electrical current. In particular, the two electrical connections of the piezo actuator can be short-circuited during plasma cleaning in order to avoid a voltage potential in the piezo actuator. To generate an electrical field, a further electrical pole can be formed by the housing, in particular by 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 poles are preferably connected to a voltage source located outside the vacuum vessel.

[0118] The process can also be carried out in such a way that each terminal of the piezo actuator forms an electrical pole for generating the plasma. Then, the plasma can be generated locally (within certain limits) between the two terminals of the piezo actuator. A combination of the two embodiments is also possible, especially in the same vacuum drying process.

[0119] The plasma can preferably be generated by means of a direct current applied between the two electrical poles (as electrodes). For example, a voltage of at least 100 volts can be applied, preferably at least about 200 volts.

[0120] The plasma can preferably be generated in argon or with argon. This has the advantage that plasma cleaning can be integrated directly into the described vacuum drying process, since argon is preferably used as the protective gas in this process. Furthermore, plasma can be formed in argon at a voltage as low as approximately 100 volts. Alternatively, oxygen can be used for plasma cleaning. This can be advantageous because oxygen has a comparatively strong cleaning effect.

[0121] Advantageously, such a plasma can be used to particularly effectively remove contaminants from the piezo actuator surface and / or from the inside of the housing. Such surface contamination or impurities can arise during the manufacturing process, e.g., when inserting the piezo actuator into the housing and / or when soldering the housing cover, and are often of organic origin. The piezo actuator in particular can be exposed to contamination in a variety of process steps, e.g., through handling. This contamination can have a detrimental effect on the operation of the encapsulated piezo actuator and thus reduce the service life of the actuator module. Advantageously, plasma can be used to thoroughly and efficiently clean the piezo actuator surface or the inner housing wall, whereby the detached contaminants or their components can be removed from the housing as a gas.

[0122] Advantageously, the piezo actuator surface can be cleaned of contaminants using plasma in the area between the connection poles of the piezo actuator, in particular between the external electrodes. Such contaminants can generate a leakage current or a short circuit between the very closely spaced positive and negative poles of the piezo actuator during operation. Furthermore, plasma can be used to clean, for example, the inside of the housing base, the inside of the housing shell, preferably the inside of the deep-drawn housing base body, and the inside of the housing cover (at least in areas not covered by the piezo actuator). Since the piezo actuator is positioned as intended in the housing during plasma cleaning, with the housing already largely sealed, subsequent contamination of the piezo actuator and / or the inside of the housing wall can be avoided as far as possible.Particular advantages can be achieved by combining the vacuum drying process with simultaneous plasma cleaning. The plasma can at least largely evaporate contaminants so that they can be sucked out of the housing as a gas. During the vacuum drying process, the vacuum can preferably be regularly increased by flowing in protective gas, preferably argon gas, for a certain period of time, e.g. a few seconds, e.g. down to about 500 mbar, and then reduced again. By periodically flooding with protective gas and subsequently reducing the vacuum, gases and any particles contained therein, which may result from evaporated contaminants, can be removed from the housing through the unsealed (filling) opening in the housing, in particular can be flushed out of it.

[0123] Preferably, after the drying process, the vacuum can be released using heat and vacuum. In particular, after the plasma cleaning is complete, the dried components and / or the plasma-cleaned piezo actuator or the housing can be exposed to or flooded with a dry gas, which is preferably heavier than air, so that the gas enters the upright housing, for example, and remains therein, preventing the ingress of air. The dry gas can preferably be argon, as described later.

[0124] To prepare the potting compound using the dried auxiliary material, preferably dried hexagonal boron nitride in powder form, the other constituents or the basic components of the potting compound, e.g., the base silicone and a crosslinker, can be evacuated and / or dried before being combined with the auxiliary material, e.g., as previously described for the housing. For example, the drying of the housing and the auxiliary material, as well as the basic components of the potting compound, could take place in a common process step, in particular in the same vacuum chamber and / or under the same parameters. Preferably, the dried (basic) components of the potting compound can be exposed to a dry gas while the vacuum is removed, in particular to create a protective gas atmosphere relative to the ambient air.It should be noted that the evacuation and / or heating of the basic components of the potting compound is an optional step and can be omitted, for example, in an inertial force-based manufacturing process.

[0125] Preferably, the housing and / or the piezo actuator and / or the auxiliary material and / or the basic components of the potting compound can be exposed to a dry gas or gas mixture, in particular at least one inert gas, following heating and / or evacuation, in particular the housing with the piezo actuator following plasma cleaning, preferably to form a protective gas atmosphere. The dry gas (mixture) of a protective gas atmosphere preferably has a residual moisture content of at most about 5 ppm, preferably of at most about 3 ppm, more preferably of at most about 2 ppm, more preferably of at most about 1 ppm, especially preferably of at most about 0.5 ppm. The dry gas preferably has a higher density than air, e.g. pure dry argon.

[0126] Particularly preferably, regardless of the specific embodiment of the method, a vacuum in which the housing and / or the piezo actuator and / or the auxiliary material and / or the (unmixed) basic components of the potting compound are arranged can be directly replaced by a protective gas atmosphere. Preferably, the evacuation and / or heating and / or the formation of a protective gas atmosphere can take place in a vacuum chamber that can be opened in the direction counter to gravity, wherein the dried components are arranged in a volume of the dry gas, in particular are completely enveloped thereby. Preferably, the housing and / or the piezo actuator and / or the auxiliary material and / or the basic components of the potting compound are shielded from an ambient atmosphere by a dry, high-density gas (as a protective gas atmosphere), even when the vacuum is eliminated.

[0127] Advantageously, the use of such a gas ensures that no moisture can penetrate into the housing and / or the auxiliary material, despite the vacuum being broken and the housing (still) being unsealed. In particular, the dry gas can collect in the housing and can then be expelled from the housing, e.g., by centrifugation, by the incoming potting compound, as described later. The use of argon with a residual moisture content of less than 3 ppm has proven advantageous, as it allows a sufficiently safe process environment for the piezo actuator in the housing to be achieved, while the procurement costs are moderate compared to undried gas.

[0128] Preferably, after completion of the drying process, the preparation of the potting compound, in particular the mixing of the basic components of the potting compound with the dried auxiliary material, can take place in such a (protective gas) atmosphere consisting of a dry gas, e.g., argon with a residual moisture content of less than 3 ppm. As already described, the auxiliary material can preferably be mixed in equal parts with a base silicone and a crosslinker before the resulting mixtures are combined to produce the flowable potting compound. Preferably, the potting compound thus produced is further processed immediately after combining the substances in order to achieve the most effective alignment of the auxiliary material platelets in the potting compound in the housing (regardless of the embodiment of the method).

[0129] The finished, flowable potting compound for introduction into the housing - regardless of the embodiment of the method - preferably has a viscosity of at least approximately 100 cSt, preferably at least approximately 200 cSt, more preferably at least approximately 300 cSt and / or at most approximately 1000 cSt, preferably at most approximately 750 cSt, more preferably at most approximately 500 cSt. In principle, a viscosity can also be higher. A flowable potting compound is preferably designed such that it can be introduced into the housing by means of a technically generated inertial force, preferably by centrifugation. In one embodiment of the method, the potting compound produced in this way can preferably be pressed or forced into the housing via the filling opening at a pressure of at least 1 bar, preferably at least 2 bar.injected, whereby in particular the ingress of (atmospheric) moisture into the housing and / or into the potting compound can be prevented by keeping the components involved in a protective gas atmosphere of dry gas during introduction. Advantageously, the dry gas, e.g. argon, which is present in the housing before filling, can be displaced from the housing when the potting compound is pressed in, whereby essentially no air humidity can enter the housing. Subsequently, in order to align the auxiliary material platelets in the potting compound, the housing and / or the potting compound in the housing can be subjected to a high pressure of e.g. 300 bar, as already described. The filling opening can then be hermetically sealed by pressing in a ball.

[0130] Alternatively, it would also be possible for the potting compound to be prepared, in particular the mixing of the basic components with the auxiliary material, under vacuum, e.g. at a pressure of 10 mbar to 100 mbar. In particular, the potting compound could be produced while continuously keeping the housing and / or the auxiliary material and / or the piezo actuator and / or the basic components of the potting compound available in a vacuum. It would also be possible for a produced flowable potting compound to be (re)evacuated before being introduced into the housing. A procedure as described above can be advantageous, for example, if the potting compound is introduced into the housing using pressure, as described, since this can prevent the potting compound and / or the gas it contains from escaping from the filling opening of the housing as a result of pressurization to align the auxiliary material platelets.However, as mentioned, it would also be possible in this embodiment for the provision of the potting compound and / or the introduction of the potting compound into the housing to take place under a protective gas atmosphere (without vacuum), which can make filling the housing technically easier.

[0131] Preferably, in one embodiment of the method, the finished potting compound can be provided in a potting storage container. In particular, the potting compound can be stored in the potting storage container such that it is shielded from the ambient atmosphere by a protective gas atmosphere. In order to introduce the potting compound into the housing, the potting storage container or potting compound storage container can be tightly coupled to a filling opening of the housing. In particular, the potting storage container can be sealingly coupled to the filling opening, e.g. via an injection needle. This can advantageously ensure that gas, e.g. argon, bubbles out of the housing during filling through the injection needle and the potting compound in the potting storage container and thereby reduces the viscosity of the potting compound in the storage container, if applicable also in the housing, wherein at the same time the individual components of the potting compound in the storage container, if applicableThis also advantageously ensures that, after the housing has been completely filled with potting compound, excess potting compound does not escape from the filling opening and, for example, contaminate a centrifuge cup. Preferably, an interior of the housing for introducing the potting compound is essentially completely filled with a dry gas, in particular with a protective gas atmosphere.

[0132] Preferably, an assembly comprising the potting reservoir and the tightly coupled housing can be centrifuged to introduce the potting compound into the housing. In particular, the centrifugation can be carried out such that a rotation axis runs substantially orthogonal to a longitudinal extension of the housing and / or the piezo actuator in the housing. In particular, a direction of introduction of the potting compound into the housing can be substantially orthogonal to the rotation axis and / or substantially parallel to a longitudinal extension of the housing.

[0133] Preferably, the housing and / or the potting reservoir coupled thereto can be pivotably mounted for centrifugation. In particular, the housing and the potting reservoir coupled thereto can be pivotably mounted such that a longitudinal extension of the housing and / or the piezo actuator gradually runs substantially transversely to the rotation axis as a result of centrifugation, particularly upon reaching a desired acceleration.

[0134] Centrifugation can be carried out, for example, using a bucket centrifuge. Centrifugation preferably takes place for at least 30 seconds and / or at most 60 seconds. Centrifugation is preferably carried out with an acceleration of at least 8000 g and / or at most 10000 g. To further increase the concentration of excipient in the potting compound in the housing, the centrifugation time and / or the acceleration can be increased, for example. Curing of the potting compound in the housing can take place at room temperature, preferably in a protective gas atmosphere. Alternatively, drying can be accelerated at temperatures of up to 90 °C. The opening can then be hermetically sealed by pressing in a ball.

[0135] Advantageously, the method allows a pretreated housing (e.g., evacuated and heated, possibly plasma-cleaned) containing a piezo actuator (possibly plasma-cleaned) along with the volume of dry gas contained within the housing to be transferred into a centrifuge without special safety precautions. The housing can, for example, only be coupled to the potting reservoir in the centrifuge, particularly under ambient atmosphere or without special conditions. Advantageously, the ingress of atmospheric moisture (via the unsealed filling opening) into the housing, which is filled with a high-density gas, can be prevented.

[0136] Another advantage is that the dry gas in the housing is forced out of the housing by the incoming potting compound as a result of the centrifugation. This means that the gas volume can be immediately exchanged for a corresponding volume of potting compound, so that no air humidity can penetrate into the interior of the housing. This allows a hermetically sealed housing with a piezo actuator arranged therein to be provided using relatively simple technical means, whereby the manufacturing process ensures that the interior of the hermetically sealed housing contains essentially no moisture. Consequently, the piezo actuator is also reliably protected from H2O molecules. Another advantage can be the provision of a potting compound, e.g.by mixing dried boron nitride and undried base silicone and crosslinker, and / or transferring a flowable potting compound into a potting storage container, even outside of a protective gas atmosphere, e.g. in room air.

[0137] In an optional step of the method, e.g., directed vibrations can be generated in the not yet cured potting compound, preferably in the excipient, to align the excipient in the potting compound. Directed vibrations can preferably be generated with a specific frequency and / or amplitude, e.g., by controlled vibration of the potting compound in the housing. Alternatively or additionally, the not yet cured potting compound in the housing, in particular the excipient therein, can be placed in an external electric field and / or an external magnetic field for a specific time to align the excipient.

[0138] Alternatively or additionally, the not yet cured potting compound in the housing, in particular the auxiliary material therein, can be subjected to a temperature treatment with at least two different temperatures in order to align the auxiliary material.

[0139] Alternatively or additionally, the process can be carried out in such a way that, in order to align the auxiliary material in the potting compound, the viscosity of the not yet cured potting compound in the housing is reduced by shearing compared to an untreated potting compound. Preferably, a specific viscosity of the potting compound can be achieved, in particular by means of sound or ultrasound.

[0140] Advantageously, the optional process steps described above can contribute to achieving and / or accelerating a specific orientation or arrangement of the auxiliary material in the potting compound. The process steps can be integrated into the manufacturing process individually or in a specific combination, even at different times. For example, the viscosity of the potting compound can be changed before centrifugation in order to enhance the centrifugation effect, whereby pressure treatment of the potting compound can be carried out, for example, after centrifugation or between two centrifugation steps. In principle, it would be possible for the potting compound not to be (yet) arranged in the housing in order to carry out one of these optional process steps.

[0141] The method can optionally provide for an auxiliary material and at least one basic component of a potting compound, e.g. a silicone gel, to be introduced into the housing at different times, in particular sequentially. It is also possible for potting compound comprising a first fraction of an auxiliary material to be introduced into the housing first, with a second fraction of a (pure) auxiliary material then being introduced into the potting compound in the housing, e.g. step by step. Accordingly, a (finished) potting compound, e.g. with a specific mass fraction of an auxiliary material, can be produced in the housing. For example, only one or more basic components for forming a flowable potting compound, e.g. a silicone gel, can initially be provided in a potting storage container. The silicone gel can be introduced into the housing by means of inertial force, e.g. by centrifugation.Preferably, the housing can be filled substantially completely with the silicone gel, although partial filling is also possible. An auxiliary substance, preferably powdered boron nitride, can then be introduced into the (remaining) silicone gel in the reservoir, with the auxiliary substance being transferred into the silicone gel in the housing by inertial force to form a potting compound. The auxiliary substance can preferably be introduced successively into the reservoir and / or the housing.

[0142] Advantageously, a volume flow of the excipient into the housing can be controlled by sequential introduction. This can advantageously create a specific spatial distribution of the excipient in the potting compound, in particular a location-dependent density. It would also be possible, for example, to create at least two regions with different excipient densities and / or a density gradient within a potting compound.

[0143] Furthermore, the method can in principle be carried out in such a way that at least two different auxiliary materials, e.g. with different physical and / or chemical properties, and / or at least two different types of potting compounds are introduced, also sequentially, into a housing.

[0144] The invention further relates to an actuator module having at least the features of an actuator module according to the invention, wherein the actuator module is obtainable by a previously described manufacturing method.

[0145] The invention is explained in more detail below with reference to the accompanying figures using exemplary embodiments. In the various figures, identical components are provided with identical reference numerals. The figures are generally not to scale. They show:

[0146] Figure 1 is a schematic sectional view of a dosing system according to the invention, Figure 2 is a schematic perspective view of an actuator module according to the invention,

[0147] Figures 3 and 4 are schematic sectional drawings through actuator modules according to the invention,

[0148] Figure 5 is a schematic and greatly enlarged view of a part of an actuator module according to the invention and a schematic view of an auxiliary material plate,

[0149] Figures 6 and 7 are schematic sectional drawings through actuator modules according to the invention.

[0150] The production of actuator modules according to the invention is described below using a possible embodiment of a manufacturing method as an example. For clarity, the method is described using a single actuator module, although a plurality of actuator modules can be produced in parallel within the method.

[0151] In a first step, a hermetically sealable housing is provided, wherein the housing has at least a housing base and a housing shell firmly connected thereto, preferably a deep-drawn housing base. A (still unconnected) housing cover is provided which has at least two electrical connections for connecting a piezo actuator, e.g. two hermetically sealed and electrically insulated feedthroughs. A piezo actuator is firmly arranged on the housing cover, wherein each connection pole of the piezo actuator is contacted by an electrical connection, e.g. by soldering. The housing cover has at least one still unsealed filling opening for a potting compound, e.g. a circular hole with a diameter of approximately 1 mm.

[0152] In a further step, the piezo actuator is introduced into the housing, in particular into the housing base body, wherein the cover and the housing shell are then firmly connected to one another to form the housing, preferably by soldering or by welding, flanging, pressing or similar.

[0153] In a further step, the housing with the piezo actuator is transferred to a vacuum chamber. It would be fundamentally possible to also insert the piezo actuator into the housing in a vacuum chamber. Subsequently, a defined amount of hexagonal boron nitride, intended for insertion into a respective housing, is placed in the vacuum chamber. The hexagonal boron nitride can, for example, be a mixture of two boron nitride powders, each with a different average particle size.

[0154] The housing, containing the piezo actuator and the boron nitride, is then heated to a temperature of 110 °C in a vacuum (10 mbar). The heating is carried out using infrared radiation for a duration of, for example, 5 hours. Optionally, the housing, containing the piezo actuator, can be subjected to plasma cleaning during the vacuum drying process.

[0155] After evacuation and heating, the vacuum is released by filling or flooding the vacuum chamber with an ultra-dry inert gas (residual humidity, e.g., < 1 ppm). The inert gas forms a protective gas atmosphere in the (open) vacuum chamber. The housing and the boron nitride, e.g., are arranged at the bottom of the vacuum chamber, so that the components are stored under a level of dry gas.

[0156] To prepare the potting compound, the boron nitride is mixed with half a base silicone and half a crosslinker before the resulting mixtures are combined to produce the potting compound. Mixing can take place under ambient or inert gas conditions.

[0157] The potting compound is transferred into a potting compound storage container, optionally shielded from the ambient atmosphere.

[0158] 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 a hardener or crosslinker can be mixed. The volume of potting compound provided depends primarily on the volume of the housing interior and is preferably dimensioned such that after centrifugation a certain amount of potting compound remains outside the housing or in the potting reservoir. Advantageously, this makes it easy to determine that the largest possible volume of silicone gel and / or boron nitride has been pressed into the housing by centrifugation and that the housing is optimally filled. Another advantage - within certain limits - is that a different ratio between boron nitride and base silicone orCross-linked materials should be chosen because the special manufacturing process using centrifugation, and preferably depending on the centrifugation parameters, automatically achieves the highest possible concentration of boron nitride in the housing. In combination with a slight excess of potting compound after centrifugation, it is easy to ensure that the potting compound in the housing has the highest possible boron nitride density.

[0159] In a further step, the housing is removed from the protective gas atmosphere and immediately transferred to a bucket centrifuge, with the unsealed filling opening preferably pointing in a direction opposite to the perpendicular direction during transfer and / or in the centrifuge, at least before centrifugation begins. Advantageously, the housing is essentially completely filled with the dry gas, which has a higher density than air, so that no ambient air enters the housing during transfer. Before being inserted into the centrifuge or in the centrifuge, the potting reservoir is tightly coupled to the filling opening of the housing.

[0160] The assembly, consisting of the potting reservoir and housing, is then centrifuged for at least 30 seconds at a (target) acceleration of 8000 g. The assembly is pivotably mounted. Upon reaching the target acceleration, a longitudinal extension of the housing and / or a longitudinal extension of the piezo actuator is essentially orthogonal to the centrifuge's rotation axis.

[0161] Centrifugation is used to introduce the potting compound into the housing, while also ensuring a preferential alignment of the boron nitride platelets with respect to the longitudinal extent of the piezo actuator. Centrifugation can also advantageously ensure that predominantly boron nitride enters the housing, so that the mass fraction of boron nitride in the hardened potting compound can be increased compared to the initial concentration in the flowable potting compound. Another advantageous effect of centrifugation is that the dry gas present in the housing is immediately replaced by the same volume of the incoming potting compound. This ensures that no moisture can enter the housing during production of the actuator module.

[0162] The volume of the flowable potting compound can be determined such that the entire interior of the housing between the piezo actuator and the housing wall is filled with the hardened potting compound. Optionally, a small volume of the interior of the housing can remain free of potting compound in order to form an expansion zone. To form the expansion zone, for example, a thin rod, in particular a thin Teflon rod, can be filled with potting compound and pushed through the filler opening to the bottom of the housing. After the potting compound has hardened, the rod can be easily pulled out, this preferably taking place in an argon atmosphere and / or after the rod has been pulled out, argon or another inert gas is filled into the formed cavity, for example via a cannula, before the filler opening is hermetically sealed using the closure ball.Advantageously, a cavity can be formed in the hardened potting compound, which extends substantially over the entire length of the housing, wherein, when the potting compound expands during operation, an increase in pressure from the inside is distributed as evenly as possible over the entire longitudinal extent of the housing.

[0163] The composition of the flowable potting compound and / or the centrifugation parameters are preferably selected such that the auxiliary material particles are evenly distributed along the entire length of the piezo actuator in the hardened potting compound. In other words, the concentration of auxiliary material particles in different regions of the potting compound is preferably predominantly the same.

[0164] The potting compound in the housing can cure at room temperature or at temperatures up to 90 °C. The housing is then hermetically sealed, if necessary by enclosing a small volume of dry gas. For this purpose, a steel or ceramic ball with a slightly larger diameter than the filler opening can be pressed into the filler opening under high force (e.g., 600 N).

[0165] An actuator module manufactured in this way can be used, for example, in a dosing system for dosing liquid to viscous dosing materials, e.g., in a jet valve, which is shown purely schematically and in section in Figure 1. Since the basic structure of such jet valves is known, only the essential elements are described below.

[0166] The dosing system 50 comprises, as essential components, an actuator assembly 51 and a fluidic assembly 52 detachably coupled thereto, wherein the coupling is effected here, for example, via a screw 62. The actuator assembly 51 essentially comprises all components that ensure the drive or movement of an ejection element 53 or a plunger 53 of the fluidic assembly 52 in a nozzle 54.

[0167] In addition to the nozzle 54 and a feed channel 56 for dosing material to the nozzle 54, the fluidic assembly 52 comprises all other parts that are in direct contact with the dosing material, as well as the elements that are required to assemble the respective parts that are in contact with the dosing material or dosing medium together or to hold them in their position on the fluidic assembly 52.

[0168] In the exemplary embodiment of the dosing system 50 shown here, the actuator assembly 51 comprises a housing block 57 with two internal chambers, namely, on the one hand, an actuator chamber 58 with an actuator module 1 located therein with at least one piezoceramic actuator 2 hermetically encapsulated in a housing 3 (Figure 3), and, on the other hand, an action chamber 59 into which a movable ejection element 53, here a plunger 53, of the fluidics assembly 52 projects. Via a lever 60, which projects from the actuator chamber 58 through an opening 61 into the action chamber 59, the plunger 53 is actuated by means of the actuator module 1 such that the dosing substance to be dosed is ejected from the fluidics assembly 52 in the desired quantity at the desired time via the nozzle 54 in an ejection direction AR. The plunger 53 closes a nozzle opening 55 and thus also serves as a closure element 53.However, since the largest part of the medium is only ejected from the nozzle opening 54 by the plunger 53 when the plunger 53 moves in the ejection direction AR towards the nozzle opening 55, it is referred to here as ejection element 53.

[0169] To control the piezo actuator 2 (Figure 3), the actuator module 1 is electrically or signal-wise connected to a control device 5, which can also be configured, for example, as part of the dosing system 50. The connection to the control device 5 is made via connecting cables 5', which are connected at the ends to actuator module control connections 28, e.g., suitable connectors 28.

[0170] The actuator module control connections 28 each contact an electrical connection 21 in the housing 3, here two contact pins 21, each of which is guided hermetically sealed and electrically insulated through a housing wall of the housing 3. In Figure 1, the actuator module 1 comprises a total of four contact pins 21, 22, which are arranged in a housing cover 32. The two outer contact pins 21 here serve to control the piezo actuator and the communication between the piezo actuator and the control device 5. The two contact pins 22 shown in the middle here are used to transmit measured values ​​from temperature sensors 27 (Figure 3) from the housing 3 to the control device 5. For this purpose, the contact pins 22 are each connected on the one hand to the control device 5 via temperature sensor connections 28' and on the other hand to the individual temperature sensors 27 in the housing 3 (not shown here).For example, measured values ​​from several temperature sensors 27 could also be forwarded to the control device 5 in a spatially resolved manner via the contact pins 22.

[0171] The piezo actuator 2 (Figure 3) arranged in the housing 3 - and above it also the housing 3 - can expand and contract again in the longitudinal direction of the actuator chamber 58 according to a wiring by means of the control device 5. The actuator module 1 can be inserted into the actuator chamber 58 from above and mounted therein in a height-adjustable manner, whereby a precise adjustment of the actuator module 1 with respect to a movement mechanism 63 is enabled. In the case shown here, the housing cover 32 is supported on the inside of the actuator chamber 58 via a support element 58', whereby the support element 58' serves as the upper abutment and can be adjusted, for example, by a screw movement (not shown) for an adjustment of the actuator module 1. Accordingly, the actuator module 1 is mounted downwards here via a pressure piece 64 tapered at the bottom on the lever 60, which in turn rests on a lever bearing 65.Via this lever bearing 65, the lever 60 can be tilted about a tilting axis K, 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, it has a contact surface 66 pointing toward the plunger 53 of the fluidic assembly 52 coupled to the actuator assembly 51, which contact surface 66 presses against the contact surface 67 of the plunger head 68.

[0172] In the illustrated embodiment, the contact surface 66 of the lever 60 is permanently in contact with the contact surface 67 of the plunger head 68, with a plunger spring 69 pressing the plunger head 68 from below against the lever 60. In principle, however, it would also be possible for a distance to exist between the plunger 53 and the lever 60 in an initial or rest position of the plunger spring 69. To enable a nearly constant preload of the drive system, the lever 60 is pressed upwards by an actuator spring 70 at the end where it comes into contact with the plunger 53.

[0173] The plunger 53 is supported by the plunger spring 69 on a plunger bearing 71, to which a plunger seal 72 is connected at the bottom. The plunger spring 69 pushes the plunger head 68 upwards away from the plunger bearing 71 in the axial direction. This also pushes a plunger tip 73 away from a sealing seat 74 of the nozzle 54. This means that without external pressure from above on the plunger head 68, a nozzle opening 55 is also unclosed in the resting (non-expanded) state of the piezo actuator 2 (Figure 3).

[0174] The dosing material is supplied to the nozzle 54 via a nozzle chamber 75 and an adjoining supply channel 56, which is connected to a dosing material reservoir 76. The fluidic assembly 52 comprises a frame part with a heating device 77, which is connected to the control device 5 via heating connection cables 78, and may additionally comprise other components.

[0175] The dosing system 50 here comprises a controllable cooling device 80, shown schematically and by way of example. A cooling medium, e.g., 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 flows through the actuator chamber 58 and can exit the dosing system 50 again via a cooling medium discharge 82. As it passes through the actuator chamber 58, the cooling medium flows along an outer surface of the housing 3, wherein the heat generated during operation of the piezo actuator, which is conducted to the housing surface via a potting compound with an auxiliary material in the housing 3 (Figure 4), can be dissipated via the cooling medium.Through the interaction of such a cooling device 80 with an actuator module 1 according to the invention, a particularly efficient heat dissipation from the piezo actuator can take place during operation of the dosing system 50, which can have an advantageous effect on the dosing precision and the service life of the piezo actuator.

[0176] Figure 2 shows a schematic and enlarged view of a possible embodiment of an actuator module 1, which comprises a housing 3 and a hermetically encapsulated piezo actuator 2 (Figure 3). The housing 3 is made of a metallic material and has a housing cover 32, a housing shell 34, and a housing base 31, wherein the elements are firmly connected to one another to form the housing 3. Unlike shown here, the housing shell 34 and the housing base 31 could also be formed as a single piece in the form of a deep-drawn housing base body 31, 34.

[0177] The housing shell 34 is designed like a metallic bellows and has a number of regularly arranged elevations and depressions, here horizontal. The longitudinal extent LEGH or longitudinal direction of the housing 3 corresponds to the longitudinal extent LEp. a or longitudinal direction of the piezo actuator 2 in the housing 3 (Figure 4).

[0178] In Figure 2, four separate electrical connections 21, 22 are arranged in the housing cover 32, here as contact pins 21, 22. The respective contact pins 21, 22 are each led through the housing cover 32 into the interior of the housing 3 via separate feedthroughs 33, 33', hermetically sealed from the outside and electrically insulated. The feedthroughs 33, 33' are realized here using glass solder and can accordingly also be referred to as glass feedthroughs 33, 33'.

[0179] Furthermore, a filling opening 37 or filling opening 37 is arranged in the housing cover 32, through which a flowable potting compound for producing the actuator module 1 can be introduced into a housing interior in the housing 3. The filling opening 37 is closed here by means of a press ball 38, e.g., a metal ball 38 with a slightly larger diameter than an inner cross-section of the filling opening 37, so that a housing interior in the housing 3 is hermetically sealed from the housing environment.

[0180] A housing interior 30 of an actuator module 1 is shown, for example, in Figure 4 and denotes a space in the housing 3, which lies between the piezo actuator 2, in particular a piezo actuator surface 20, and an inner side 35 of the housing wall 31, 32, 34. The housing interior 30 is essentially completely filled with a potting compound 4, wherein a small expansion region 44, e.g., a volume of a dry gas, is arranged in the housing interior 30. Unlike shown in Figures 3 and 6, the expansion region 44 can preferably be a thin, elongated cavity 44, which, for example, in a direction LEp aor LEGH in the potting compound 4, whereby the potting compound 4 then extends from the housing base 31 to the housing cover 32 (apart from the cavity 44). Such an expansion region 44 is shown as an example in Figure 4. Since the actuator modules 1 from Figures 3 and 4 - apart from the expansion region 44 - are similarly constructed and differ essentially in terms of their view and sectional plane, the actuator modules 1 will be described together. Both actuator modules 1 from Figures 3 and 4 are greatly enlarged and shown purely schematically.

[0181] The actuator module 1 in Figure 3 comprises a housing 3 with a housing cover 32, a housing shell 34, and a housing base 31. In principle, and unlike what is shown here, the actuator module 1 could also have a deep-drawn housing 3, in which case the housing shell 34 and a housing base 31 would be formed as a single piece. The remaining structure of the actuator module 1 or the housing 3 could then be as shown in Figures 3 and 4.

[0182] Four electrical terminals 21, 22 are arranged in the housing cover 32, each of which is hermetically sealed and electrically insulated from the outside into the housing 3 by means of a glass solder feedthrough 33 (only partially visible). The contact pins 21, 22 are connected to actuator module control terminals 28 and temperature sensor terminals 28', respectively, which terminals 28, 28' are coupled to a control device 5.

[0183] The two outer contact pins 21 each contact a terminal of the piezo actuator 2 in the housing interior 30. This is particularly visible in Figure 4, where an electrical connection 21 contacts an outer electrode 23 as the terminal of the piezo actuator 2. The outer electrode 23 runs along a longitudinal extension LEp a of the piezo actuator 2 and connects the internal electrodes 24, which are guided 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 the section in Figure 3. By arranging two external electrodes 23 on two opposite sides of the piezo actuator surface 20 (only one external electrode 23 is visible in Figure 4), the internal electrodes 24 are connected in parallel and combined into two groups, whereby the piezo actuator 2 can be connected via the two electrical connections 21 (Figure 3).

[0184] The internal electrodes 24 are arranged between thin layers of a piezoactive material 25, wherein in the frontal areas 26 of the piezo actuator 2 or in the actuator head

[0185] 26 and no piezoactive material 25 is arranged in the actuator base 26, so that these areas can be referred to as inactive areas 26 (Figure 3).

[0186] Along the longitudinal extension LEp a of the piezo actuator 2 are several temperature sensors

[0187] 27 are arranged on the piezo actuator surface 20. Furthermore, temperature sensors 27 are arranged in different areas of an inner side 35 of the housing 3. The temperature sensors 27 are each connected to the two inner connection pins 22 (Figure 3) via connections not shown here, wherein measured values ​​are transmitted to the control device 5 via the temperature sensor connections 28'. These connection pins are not shown in Figure 4. Unlike shown in Figures 3 and 4, temperature sensors 27 could also be arranged on an outer side 36 of the housing 3. The potting compound 4 in the housing interior 30 in Figure 3, as well as in Figures 4 to 7, comprises hexagonal boron nitride 40 (a-BN, hexagonal) in powder form as an auxiliary material 40.For the sake of clarity, the auxiliary material 40 is schematically shown in Figures 3 and 4 only in a part of the housing interior 30, which is located to the right of the piezo actuator 2, whereby in reality the entire potting compound 4 in the housing 3 comprises the auxiliary material 40. The auxiliary material 40 is present in the form of auxiliary material platelets 40 in the potting compound 4, whereby the individual auxiliary material platelets 40 are aligned essentially unidirectionally, in particular with respect to the longitudinal extent LEp. a of the piezo actuator 2. The auxiliary material plates 40 are arranged in the potting compound 4 in such a way that an approximately uniform distribution of auxiliary material plates 40 along the longitudinal extent LEp a of the piezo actuator 2 (Figure 4).

[0188] The specific orientation of the individual auxiliary material plates 40 in the potting compound 4 is greatly enlarged and shown purely schematically in the section from an actuator module according to the invention in Figure 5A. The individual auxiliary material plates 40 are substantially uniformly arranged along the longitudinal extent LEp a of the piezo actuator 2, wherein the respective auxiliary material plates 40 are aligned in the potting compound 4 such that a longitudinal extension LEHS of the auxiliary material plates 40 is substantially orthogonal to the longitudinal extension LEp a of the piezo actuator 2.

[0189] As shown in Figure 5B by way of example and purely schematically, the longitudinal extension LEHS is defined as the longest extension of an excipient platelet 40 in one direction (here in the x-plane), whereby a maximum extension of the excipient platelet 40 in the z-plane corresponds to a width BHS. Due to the extension of the excipient platelet 40 in the x- and z-planes, two base surfaces 41 are formed, whereby a height HHS of the excipient platelet 40 orthogonal thereto is comparatively small. In reality, an outer contour of the excipient platelets can be irregular, whereby the two base surfaces 41 do not have to be exactly plane-parallel, unlike shown here.

[0190] Such auxiliary material platelets 40 are arranged essentially unidirectionally in the potting compound 4 such that in all areas of the housing interior 30, in particular in an area between the piezo actuator surface 20 and the inner side 35 of the housing 3, essentially the same density of auxiliary material platelets 40 is present in the potting compound 4. The purely schematic representation in Figure 5A shows that some of the auxiliary material platelets 40 are directly adjacent to the piezo actuator surface 20, e.g., are in direct contact with it. This is advantageous, on the one hand, because hexagonal boron nitride 40 (as auxiliary material 40) as a dry lubricant enables sliding mounting of the piezo actuator 2 during operation. Furthermore, the resulting heat loss can be dissipated particularly efficiently from the piezo actuator surface 20 via the direct contact. The heat dissipation from the piezo actuator surface 20 typically occurs predominantly in a lateral direction during operation, e.g.,in a heat conduction direction WL.

[0191] The auxiliary material plates 40 are arranged unidirectionally and essentially orthogonally to the piezo actuator surface 20 such that at least a majority of the auxiliary material plates 40 in the potting compound 4 are in contact with at least one other auxiliary material plate 40 via contact points 45. As shown in Figure 5A, a continuous bridge of auxiliary material plates 40 can be formed via such contact points 45, extending as directly as possible from the piezo actuator surface 20 to the inner side 35 of the housing 3. Advantageously, a thermal conduction path WLP for waste heat can be formed along such a bridge. The direction of each thermal conduction path WLP essentially corresponds to the heat conduction direction WL of the piezo actuator 2 during operation.

[0192] Due to the special design and orientation of the auxiliary material plates 40 in the potting compound 4, heat loss from the piezo actuator 2 can be dissipated during operation in a targeted manner and over the shortest possible path to the inner side 35 of the housing 3, in particular to the housing shell 34. Furthermore, due to the shape and orientation of the auxiliary material plates 40, the number of contact points 45 can be kept as small as possible, which improves the thermal conductivity along the bridges of auxiliary material plates 40 and the efficiency of the thermal conduction paths WLP. Unlike what is shown in Figure 5A, a large number of such thermal conduction paths WLP will generally run through the potting compound, in particular, substantially evenly distributed along the longitudinal extent LEp. a of the piezo actuator 2.

[0193] Figure 6 shows, purely schematically and greatly enlarged, an actuator module 1 in a manufacturing process according to the invention. The actuator module 1 comprises a housing 3 with a housing cover 32, a housing shell 34, and a housing base 31, wherein the elements 32, 34, 31 are firmly connected to one another. Unlike shown here, the housing shell 34 and the housing base 31 can also be formed by means of a deep-drawn housing 3. An as yet unsealed filling opening 37 for potting compound 4 is arranged in the housing cover 32, wherein the potting compound 4 is already arranged in the housing interior 30 in the process stage shown here. A part of the housing interior 30 contains no potting compound 4 and forms an expansion region 44 in the hardened state of the potting compound 4, wherein the expansion region 44, unlike shown here, is preferably an elongated cavity. The other components of the housing 3, e.g.the electrical connections are not shown here and could be implemented similarly to Figure 3.

[0194] The housing 3 is located in a pressure chamber 6, within which a dry gas or silicone oil under high pressure p is arranged, e.g., pure dry argon at a pressure of approximately 300 bar. Contrary to what is shown purely schematically here, the pressure p acts throughout the entire pressure chamber 6 and not just in the direction of the arrow shown. The high pressure p can act via the filler opening 37 on the potting compound 4 in the housing interior 30 and, in particular, on the auxiliary material platelets 40 located in the potting compound 4.

[0195] In Figure 6, the individual auxiliary material plates 40 are not yet arranged unidirectionally, but rather randomly or chaotically in the potting compound 4. Here (and in Figure 7), for the sake of clarity, the auxiliary material plates 40 are schematically arranged only in a part of the housing interior 30, which is to the right of or above the piezo actuator 2, although in reality the entire potting compound 4 in the housing 3 comprises the auxiliary material 40. In order to align the auxiliary material plates 40 essentially completely unidirectionally with their longitudinal extent transverse to the longitudinal extent of the piezo actuator 2, e.g., as shown in Figure 5A, the unsealed housing 3 can be pressurized with the gas or silicone oil under pressure p for a period of 10 minutes, for example. The filling opening 37 can then be hermetically sealed using a press ball 38 (Figure 2).

[0196] Figure 7 shows, purely schematically and greatly enlarged, an actuator module 1 in a manufacturing method according to the invention. The actuator module 1 comprises a housing 3, which is arranged in a centrifuge cup 7 of a centrifuge (not shown in detail), wherein the centrifuge cup 7 is pivotally mounted according to a pivoting direction SR. A potting compound 4 with excipient platelets 40 is already arranged in the housing interior 30, wherein the individual excipient platelets 40 are already arranged predominantly unidirectionally. The housing cover 32 comprises a filling opening 37, to which a potting compound storage container 43 is currently coupled. The potting compound storage container 43 enters the housing interior 30 via an injection needle 42. The injection needle 42 is arranged in a sealing manner in the filling opening 37.

[0197] The other components of the housing cover 32 are not shown here and could, for example, be implemented similarly to Figure 3.

[0198] In Figure 7, essentially the entire housing interior 30 is already completely filled with potting compound 4. Preferably, potting compound 4 can still remain in the potting reservoir 43 after centrifugation has ended, which is shown schematically in Figure 7. As a result, for example, the mass fraction of auxiliary material platelets 40 in the potting compound 4 in the housing 3 can be increased, since as a result of the centrifugation the auxiliary material platelets 40 preferentially enter the housing 3, with the remaining potting compound 4, in particular the basic components of the potting compound such as a silicone gel, then predominantly remaining outside the housing 3. For example, excess potting compound 4 can be visibly arranged in layers in a transparent potting reservoir 43, in particular separated according to any necessarystill present boron nitride 40 (as auxiliary material 40) and the silicone gel, wherein the boron nitride 40 is predominantly arranged in the area of ​​the injection needle 42 and in the right part of the potting reservoir 43.

[0199] The process section shown in Figure 7 shows centrifugation at a set speed. The centrifuge cup 7 is pivoted open in the area of ​​the housing base 31 so far that a centrifugal force Fzf is essentially parallel to the longitudinal extent LEGH of the housing 3 or essentially parallel to the longitudinal extent LEp a of the piezo actuator 2. The centrifugal force Fzf acts essentially orthogonally to the longitudinal extension LEHS of the auxiliary material platelets 40. In particular, the centrifugal force Fzf acts essentially orthogonally on a base surface 41 of the auxiliary material platelets 40 (Figure 5B).

[0200] The longitudinal extension LEHS of the auxiliary material platelets 40 is predominantly parallel to the rotational axis R of the centrifuge. Using the method described in detail and by way of example in Figure 7, the potting compound 4 can be introduced into the housing 3, wherein the same method aligns the auxiliary material platelets 40 in the potting compound 4, as described in more detail in Figure 5A, for example.

[0201] Preferably, after centrifugation has ended, the injection needle 42 can be removed from the housing 3, wherein an elongated rod can then optionally be inserted into the filling opening 37 up to the housing bottom 31 in order to form an expansion area in the curing potting compound 4 above it.

[0202] Finally, it should be noted once again that the actuator modules described in detail above are merely exemplary embodiments that can be modified in a variety of ways by those skilled in the art without departing from the scope of the invention. For example, a hermetically sealable housing produced by deep drawing can be used in the respective exemplary embodiments. Furthermore, the use of the indefinite articles "a" or "an" does not preclude the possibility that the relevant features may be present multiple times.

[0203] List of reference symbols

[0204] 1 actuator module

[0205] 2 Piezo actuator / component

[0206] 3 housings

[0207] 4 Potting compound

[0208] 5 Control device

[0209] 5' connection cable

[0210] 6 pressure chamber

[0211] 7 centrifuge buckets

[0212] 20 Piezo actuator surface

[0213] 21 Contact pin (piezo actuator)

[0214] 22 Contact pin (temperature sensor)

[0215] 23 Outer electrode

[0216] 24 Internal electrode

[0217] 25 Piezoactive material

[0218] 26 Inactive area

[0219] 27 Temperature sensor

[0220] 28 actuator module control connections

[0221] 28' temperature sensor connections

[0222] 30 Housing interior

[0223] 31 Case back

[0224] 32 housing cover

[0225] 33, 33' feedthrough / glass feedthrough

[0226] 34 Housing shell

[0227] 35 Inside

[0228] 36 Outside

[0229] 37 Filling opening

[0230] 38 press balls

[0231] 40 Auxiliary material / Auxiliary material platelets / Boron nitride

[0232] 41 floor space

[0233] 42 Injection needle

[0234] 43 potting storage containers

[0235] 44 Expansion area

[0236] 45 Contact point

[0237] 50 Dosing system 51 Actuator assembly

[0238] 52 Fluidics assembly

[0239] 53 Ejection element / plunger

[0240] 54 nozzle

[0241] 55 Nozzle opening

[0242] 56 feed channel

[0243] 57 Housing block

[0244] 58 Actuator chamber

[0245] 58' support element

[0246] 59 Action Chamber

[0247] 60 levers

[0248] 61 Breakthrough

[0249] 62 screw

[0250] 63 Movement mechanism

[0251] 64 Pressure piece

[0252] 65 lever bearings

[0253] 66 Contact surface (lever)

[0254] 67 Contact surface (ram head)

[0255] 68 Tappet head

[0256] 69 Tappet spring

[0257] 70 actuator spring

[0258] 71 tappet bearings

[0259] 72 tappet seal

[0260] 73 plunger tip

[0261] 74 Sealing seat

[0262] 75 Nozzle chamber

[0263] 76 Dosing reservoir

[0264] 77 Heating system

[0265] 78 heating connection cables

[0266] 80 Cooling device

[0267] 81 Cooling medium supply

[0268] 82 Cooling medium discharge

[0269] AR ejection direction

[0270] BHS Wide Excipient Plates

[0271] Fzf centrifugal force

[0272] HHS Height of auxiliary material plate K Tilt axis

[0273] LEßh Longitudinal extension housing

[0274] LEHS longitudinal extension of excipient platelets

[0275] LEpa longitudinal extension piezo actuator p pressure

[0276] R rotation axis

[0277] SR swivel direction

[0278] WL heat conduction direction

[0279] WLP heat conduction path

Claims

Patent claims 1. Actuator module (1) with a hermetically sealed housing (3) with at least one piezo actuator (2) arranged in the housing (3) and with electrical connections (21, 22) at least for the piezo actuator (2), which connections (21, 22) are guided through a housing wall (31, 32, 34), wherein a housing interior (30) between the piezo actuator (2) and the housing wall (31, 32, 34) contains a potting compound (4) which electrically insulates the housing wall (31, 32, 34) from the piezo actuator (2), and wherein the potting compound (4) is a solid and comprises at least one particulate, thermally conductive, dielectric auxiliary material (40), wherein the auxiliary material (40) is arranged in the potting compound (4) such that heat dissipation from the housing wall (31, 32, 34) is possible via the potting compound (4), in particular via the auxiliary material (40). Piezo actuator (2) to housing wall (31 , 32, 34) during operation.

2. Actuator module according to 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), further preferably at least about 100 W / (m K), further preferably at least about 200 W / (m K), particularly preferably at least about 300 W / (m K), and in particular at least about 400 W / (m K).

3. Actuator module according to one of the preceding claims 1 or 2, wherein the auxiliary material (40) is present in the potting compound (4) in the form of platelets (40) and / or wherein the auxiliary material (40) is arranged at least partially, in particular substantially completely, in the potting compound (4) such that a longitudinal extension (LEHS) of a respective platelet (40) of the auxiliary material (40) extends transversely, preferably substantially orthogonally, to a longitudinal extension (LEp a ) of the piezo actuator (2).

4. Actuator module according to one of the preceding claims, wherein the auxiliary material (40) is boron nitride (40), in particular hexagonal boron nitride (40), and / or wherein the size of a platelet (40) of the auxiliary material (40) is at least about 10 pm, preferably at least about 20 pm, preferably at least about 30 pm and / or at most about 100 pm, preferably at most about 80 pm, preferably at most about 60 pm, and / or wherein the auxiliary material (40) comprises a mixture of particles, preferably platelets (40), with different mean sizes.

5. Actuator module according to one of the preceding claims, wherein the potting compound (4) contains a silicone gel comprising at least a base silicone and at least one crosslinking agent.

6. Actuator module according to one of the preceding claims, wherein a proportion of auxiliary material (40), in particular hexagonal boron nitride (40), in the potting compound (4) in the housing (3) is at least about 50 wt.%, preferably at least about 60 wt.%, preferably at least about 65 wt.%, in particular at least about 70 wt.%.

7. Method for manufacturing an actuator module (1) with a hermetically sealed housing (3) and at least one piezo actuator (2) arranged in the housing (3), in particular an actuator module (1) according to any one of the preceding claims 1 to 6, comprising at least the following steps: Providing a hermetically sealed housing (3) with electrical connections (21, 22) for at least one piezo actuator (2), wherein the connections (21, 22) are guided through a housing wall (31, 32, 34), Inserting at least one piezo actuator (2) into a housing interior (30) of the housing (3), optionally cleaning at least one part of the piezo actuator (2) and / or at least one part of an inner surface (35) of the housing wall (31, 32, 34) by means of a plasma, Providing a potting compound (4) which, preferably in its hardened state, electrically insulates the housing wall (31, 32, 34) from the piezo actuator (2), introducing the, preferably flowable, potting compound (4) into the housing interior (30) between the piezo actuator (2) and the housing wall (31, 32, 34), preferably via a filling opening (37) in the housing (3), wherein the potting compound (4), in particular after hardening in the housing (3), is a solid and comprises at least one particulate, thermally conductive, dielectric auxiliary material (40), wherein the auxiliary material (40) is arranged in the potting compound (4) such that heat is dissipated from the piezo actuator (2) to the housing wall (31, 32, 34) during operation via the potting compound (4), in particular via the auxiliary material (40), and hermetically sealing the housing (3).

8. Method according to claim 7, wherein a flowable potting compound (4) is provided such that the potting compound (4) to be introduced into the housing (3) comprises a silicone gel made of at least one base silicone and a crosslinking agent and / or wherein to Provision of a flowable potting compound (4) a first half-share of the auxiliary material (40) is mixed with at least a share of a base silicone and a second half-share of the auxiliary material (40) is mixed with at least a share of a crosslinking agent, wherein the mixtures thus obtained are mixed together to produce the potting compound (4) to be introduced into the housing (3).

9. A method according to claim 7 or 8, wherein a flowable potting compound (4) is produced such that the respective proportion of base silicone and / or crosslinking agent in the potting compound (4) before the potting compound (4) is at least about 10 wt.%, preferably at least about 20 wt.%, more preferably at least about 25 wt.%, in particular at least about 30 wt.%, is present before the potting compound (4) is introduced into the housing (3), and / or wherein a flowable 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 the potting compound (4) is introduced into the housing (3) is at least about 10 wt.%, preferably at least about 20 wt.%, more preferably at least about 25 wt.%, more preferably at least about 30 wt.%, in particular at least about 35 wt.%, and / or at most about 50 wt.%, more preferably at most about 40 wt.%.

10. Method according to any one of the preceding claims 7 to 9, wherein the auxiliary material (40), in particular hexagonal boron nitride (40), is arranged in the form of platelets (40) in the flowable potting compound (4) and wherein the potting compound (4) in the housing (3) is subjected to a pressure medium for a certain time, wherein preferably a pressure (p) is at least about 100 bar, preferably at least about 200 bar, particularly preferably at least about 300 bar or more.

11. Method according to any one of the preceding claims 7 to 10, wherein the auxiliary material (40), in particular hexagonal boron nitride (40), is arranged in the form of platelets (40) in the flowable potting compound (4) and wherein the potting compound (4) is subjected in the housing (3) to a certain inertial force (Fzf), in particular a centrifugal force (Fzf).

12. Method according to any one of the preceding claims 7 to 11, wherein the auxiliary material (40), in particular hexagonal boron nitride (40), is arranged in the form of platelets (40) in the flowable potting compound (4) and wherein the potting compound (4) is introduced into the housing (3) by means of a specific inertial force (Fzf), in particular a centrifugal force (Fzf), acting on the housing (3) and / or on the potting compound (4).

13. Method according to claim 11 or 12, wherein the inertial force (Fzf) is substantially in the direction of a longitudinal extent (LEGH) of the housing (3), preferably in the direction of a longitudinal extent (LEp) a ) of the piezo actuator (2), acts on the potting compound (4), in particular on the auxiliary material (40) in the potting compound (4).

14. Metering system (50) for a metering substance comprising a nozzle (54) for dispensing metering substance, a feed channel (56) for metering substance, an ejection element (53) and an actuator module (1) coupled to the ejection element (53) and / or the nozzle (54) according to one of claims 1 to 6.

15. Hermetically sealed housing (3) with at least one component (2) arranged in the housing (3), preferably a piezo actuator (2), and with electrical connections (21, 22) at least for the component (2), which connections (21, 22) are guided through a housing wall (31, 32, 34), wherein the housing (3) has a one-piece formed housing base body (31, 34) and a housing cover (32) and wherein the housing base body (31, 34) is obtainable by deep drawing.

16. Use of an actuator module (1) according to one of claims 1 to 6 in a metering system (50) with at least one feed channel (56) for metering material, a nozzle (54) for dispensing metering material and an ejection element (53), wherein the actuator module (1) cooperates with the ejection element (53) and / or the nozzle (54) during operation for metering material dispensing.

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