Weighing System

Abstract

The present invention relates to a weighing system (1) for weighing a measuring medium, comprising a frame housing unit (2) and a lever mounting unit (3) with a lever mount (4), the lever mounting unit (3) being supported on the frame housing unit (2). The invention further comprises a lever (30), preferably an asymmetric lever (30), supported by the lever mount (4) for rotation about a tilt axis (R), the lever (30) comprising a two-sided lever arm (31) extending generally in the longitudinal direction (30L) of the lever (30), one lever arm side (35), preferably the longer lever arm side (35), having a first actuator engagement point (36) close to the tilt axis, one lever arm side (35) contacting the discharge element (13), preferably the ram (13), at an end portion (33) away from the tilt axis, and the other lever arm side (32), preferably the shorter lever arm side (32), having a second actuator engagement point (37) close to the tilt axis. The invention further comprises two actuators (50a, 50b) which exert opposing tilting moments on the lever (30) at the first and second actuator engagement points (36, 37) during operation, the actuators (50a, 50b) being arranged at an angle to each other. The lever mounting unit (3), the lever (30) and the two actuators (50a, 50b) together form a movement mechanism (4, 30, 50a, 50b), which is supported on the frame housing unit (2) by at least one spring element (21), preferably a set of disc springs (21), which is preferably arranged to support the lever mounting unit (3) against the frame housing unit (2) via the two actuators (50a, 50b) as well as via the lever (30).

Description

[Technical Field]

[0001] The present invention relates to a metering system for metering a metering medium, the metering system comprising: a frame housing unit; a lever mounting unit with a lever mount supported on the frame housing unit; and a lever supported by the lever mount for rotation about a tilt axis, the lever comprising a substantially longitudinally extending two-sided lever arm, one lever arm side having a first actuator engagement point close to the tilt axis and contacting a dispensing element at an end portion away from the tilt axis, and the other lever arm side having a second actuator engagement point close to the tilt axis, the metering system further comprising two actuators for exerting opposite tilting moments on the lever at the first and second actuator engagement points during operation. [Background technology]

[0002] Metering systems of the above-mentioned type are usually used to systematically meter a medium to be metered (generally a liquid to viscous substance to be metered). In the context of so-called "micrometering technology", it is often necessary for very small amounts of metering medium or substance, respectively, to be applied to a target surface with extremely precise accuracy, i.e. without contact, i.e. without direct contact between the measuring system and the target surface. Such contactless processes are also often called "jet processes". The metering of adhesive dots, solder paste, etc. when mounting printed circuit boards or other electronic components, or the application of transducer material for LEDs are common examples for this.

[0003] The key requirement is to deliver the metered medium to the target surface with high precision, i.e., at the exact time, at the exact position, and in an accurately metered amount. This can be achieved, for example, by droplet-like ejection of the metered medium through the nozzle of the metering system. The ejection of individual droplets in a similar manner, for example, in a process of the type known as an "inkjet process," as also used in inkjet printers, is a preferred process. The size of the droplets, or the amount of medium per droplet, can be predetermined as accurately as possible by the nozzle effect achieved, as well as by the settings and controls.

[0004] To expel the medium from the metering system, a movable discharge element (typically a ram) can be arranged in the nozzle of the metering system. Inside the nozzle, the ram can be pressed or moved at a relatively high speed in the direction of the nozzle opening and thus in the forward metering direction, so that droplets of medium can be expelled and then retracted again.

[0005] The ram can usually be brought to a closed position in that it tightly connects to the sealing seat of the nozzle opening at the nozzle and remains there temporarily. In the case of more viscous metering media, it may also be sufficient for the ram to simply remain in a retracted position, i.e., away from the sealing seat, without droplets of medium leaking out of the nozzle opening.

[0006] The invention can be used in the case of all the alternative methods mentioned above, independently of the specific ejection principle, i.e. in the case of a jet process, an open inkjet process or even with a simple closure element.

[0007] Due to the desire to continuously achieve higher machine productivity or higher operating speeds, there is currently a further demand to apply metering medium to the target surface faster than ever before, and therefore, for example, to apply droplets to the target surface at a high ejection frequency and therefore in rapid temporal succession.

[0008] This results in vibrations that can propagate from dynamically excited components in the weighing system to the entire weighing system. Due to the fact that a weighing system is a vibration-generating system, excitations in the structure of this system can be optionally enhanced. In particular, the natural frequencies of the system can be excited thereby. If the natural frequencies and the excitation frequencies coincide, resonances can be generated, causing undesired relative movements that can negatively affect the weighing behavior, in particular the weighing accuracy and the quality of the weighing.

[0009] Previously, known metering systems could only theoretically achieve such a desired dispensing frequency. Tests have shown that currently known metering systems can no longer operate stably and smoothly at the desired dispensing frequency in terms of the required quality standards. Thus, the metering quality, as well as the metering accuracy, is reduced in such a way that it is impossible to achieve satisfactory metering results at a given metering frequency.

[0010] To address this issue, preload springs, and thus springs that directly preload the actuator, are often used in practice. In the case of high dynamic stresses, the components (especially the actuator and frame component parts) heat up to different degrees, as well as unevenly. This results in a misalignment of the closure element relative to the nozzle and therefore the metering result. In the case of high excitation frequencies, natural resonance of the dynamically vibrating preload spring may also result, which then also negatively affects the metering process. In the desired frequency range, this may result in interference and / or resonance effects that negatively affect the metering result in the short term and lead to increased friction or increased wear of the respective components in the long term. Summary of the Invention [Problem to be solved by the invention]

[0011] The object of the present invention is therefore to improve known weighing systems, in particular to specify a special rapid weighing system, by means of which a higher measurement frequency is achieved together with a high measurement accuracy and a high measurement quality of the weighing medium on the workpiece. [Means for solving the problem]

[0012] This object is solved by a weighing system according to claim 1 of the appended claims.

[0013] As mentioned above, the weighing system according to the present invention for metering a metering medium on a workpiece or on a substrate comprises a frame housing unit. By frame housing unit is meant a housing of the weighing system that "frame-like" surrounds, and therefore a housing that encloses most of the components of the weighing system on its rear side, such as the motion mechanisms of the weighing system described below. For functional reasons, the frame housing unit is embodied to be relatively large and inertial, since it serves as a stable counter-bearing or inertial frame of the weighing system, so that particularly dynamic components, such as the motion mechanisms of the weighing system, can be elastically supported thereon, as will be described further below.

[0014] The frame housing unit is designed to have little or no response to high vibrations or high motion frequencies of the motion mechanism, and therefore to behave statically relative to the dynamic motion mechanism, i.e., to have correspondingly little and large self-forces, thereby ensuring consistently good metering properties in that it quiets the entire weighing system.

[0015] It is preferably possible to form the first main mass of the weighing system with a low natural frequency that is as insensitive as possible to the frequency range of the lighter individual components of the weighing system's dynamic mechanism that move at higher frequencies, i.e., if possible, a first main mass that is not excited to vibrate in the above-mentioned frequency range, so that developments related to the interference of resonant vibrations or reverberations of the entire weighing system in the weighing operation are substantially eliminated based on different vibration frequencies.

[0016] As also mentioned above, the metering system according to the invention further comprises a lever mounting unit supported on the frame housing unit, which comprises at least one lever mount for a lever of the metering system. The lever mounting unit is advantageously separated from the frame housing unit insofar as it is structurally protected against tilting and rotation, but is capable of shifting along a depth or metering axis relative to the frame. This shift can be prevented by a piezoelectric actuator that is spring-supported between the frame housing unit and the lever mounting unit via the lever mounting unit. As described below, this is achieved so that thermally identical changes in the two piezoelectric actuators and / or thermal changes in the frame housing unit result in an appropriate change in the distance between the nozzle and the dispensing element.

[0017] The lever mounting unit is preferably located partly inside the frame housing unit and partly outside the frame housing unit and is therefore supported by the frame housing unit.

[0018] The lever mount of the lever mounting unit is the first rotary mounting part of the rotary mount, which is part of the movement mechanism. The rotary or tilting mount is formed by the lever mount and the lever and indirectly transmits the forces alternately generated for the metering operation of the two actuators to the discharge element to be driven. The discharge element, which in this configuration of the invention can preferably also be a ram, conveys the metering medium at least in portions from the nozzle according to one of the above-mentioned metering methods or types.

[0019] In its literal meaning, a lever mount serves the purpose of supporting a lever that is rotatably or tiltably supported about the tilt axis of the tilt mount, so that the lever can be moved from an initial rest position (i.e. a horizontal central position) relative to the tilt axis in a given metering direction of the weighing system or tilted at least at a certain angle that determines the stroke length. The tilt or rotation axis on which the lever is tiltably supported also extends horizontally, but perpendicular to the lever or perpendicular to the longitudinal direction of the lever.

[0020] 1, although relative directional designations such as "top," "bottom," "top-side," "bottom-side," "laterally," "left," "right," "longitudinal," etc., herein optionally refer to the illustrations in the drawings described further below. This means that metering is mostly performed on the workpiece during the jetting process such that the metered droplets, in free fall or flight, essentially lightly strike the workpiece due to gravity, and thus metering occurs in the metering direction or depth direction below.

[0021] In the broadest sense, a lever simply refers to a mechanical force transducer made of a rigid body and usually rotatably supported about a center of rotation (i.e., the tilt axis). The lever of the metering system according to the invention comprises a two-sided or two-arm lever arm extending substantially longitudinally. By "substantially longitudinally" we mean that the lever extends in at least its main direction of extension through the metering system (i.e., in the longitudinal direction of deflection between the dispensing element and the actuator). However, the lever is generally a three-dimensional component that also extends at least commensurately in two other orthogonal spatial directions. For example, it may extend laterally (parallel to the tilt axis) between two side surfaces or in depth (perpendicular to the tilt axis and the longitudinal axis) in the direction of the lever mount, at least to the extent that it measures at least part of its main longitudinal extension in these directions.

[0022] As is generally conventional, the term "lever arm" herein also refers to the portion (or length) of a lever that extends from the tilt axis or rotation axis of the lever to the engagement point at which a force acts or engages the lever. A two-sided or two-arm lever arm thus has two such portions or two lever arms, each with an engagement point at which a force engages the lever. Hereinafter, a lever arm may also be referred to as a lever arm side of a lever. The distance of an engagement point from the common rotation axis is also referred to as the lever arm length. Thus, in principle, the longer the distance of the engagement point from the tilt axis, the longer the lever arm length and the smaller the force can be, to compensate for the correspondingly larger force with a shorter lever arm length.

[0023] In the case of the metering system according to the invention, one of the lever arm sides of the two-sided lever arm further has a first actuator engagement point, i.e., a first point, close to the tilt axis where the force is involved. Away from the tilt axis, on its end portion, the respective lever arm side comes into contact with the nozzle of the metering system by means of the already mentioned discharge element. As intended, the movement of the lever in the metering direction of the metering system is transmitted to the discharge element. The terms "close to the tilt axis" and "away from the tilt axis" are related to each other. Therefore, an arrangement close to the tilt axis simply means that the respective component is arranged closer to the tilt axis than a component arranged away from the tilt axis.

[0024] As described below, the other lever arm side similarly has a second actuator engagement point, and therefore a second point, near the tilt axis, where the force alternates with the first point. Each lever arm side can be formed symmetrically with the other lever arm side, for example, simply not extending anywhere away from the tilt axis on the lever arm side with the second actuator engagement point (away from the discharge element). Preferred designs or further developments of the levers are described below.

[0025] The weighing system according to the present invention further comprises two actuators which, during operation, exert opposing tilting moments on the lever at the first and second actuator engagement points.

[0026] In the context of the present invention, tilting moment is simply understood as the torque that ensures that the lever is tilted at a specific angle and that the dispensing element in contact is therefore moved in a defined manner for metering purposes. However, the term "tilting moment" as used herein does not refer to a standard tilting moment in the case where the body to which it is applied tilts or rolls starting from this specific tilting moment. Rather, the tilt literally refers to the tilt of the lever at a specific angle relative to the horizontal or central position in which the lever is located, at least initially before start-up or when the actuator is currently de-energized.

[0027] The actuator engagement point refers to at least a discrete point of contact or actuator point in terms of the actuator contact point or engagement point on the lever where the actuator engages or contacts the lever. However, the actuator engagement point can also consist of multiple points, lines, or surfaces. For example, the actuator engagement point can be formed as two longitudinal engagement lines or actuator contact points extending transversely to the lever and perpendicular to the direction of action of the actuator. This is suitable for limiting the rotational or tilting movement of the lever relative to the lever mount to only a given tilting moment about the tilt axis to move the dispensing element in the desired metering direction. Therefore, essentially no additional rotating components can be provided in the system, which could, for example, cause additional friction or wear. A preferred design of the actuator is also described below.

[0028] According to the invention, the actuators of the above-mentioned weighing system are arranged at an angle to each other. "Arranged at an angle to each other" means that on the front side, the actuators extend at an angle towards each other in a common plane, or on the other side or behind the tilt axis, they are angled and directed towards a common point. In further exemplary embodiments described below, they are, for example, directed towards a point below the horizontal plane of the tilt axis of the lever mount and the tilt bearing of the lever.

[0029] In any case, however, "arranged at an angle relative to one another" particularly means that the actuators or their directions of action are arranged or aligned at an angle of less than 180° but greater than or equal to 0° relative to one another. Thus, as will be described in more detail below, the present invention departs from the fact that the actuators are aligned completely opposite one another or parallel or anti-parallel to one another.

[0030] The lever mounting unit (with the lever mount), the lever and the two actuators together further form a movement mechanism, which according to the invention is supported on the frame housing unit by at least one spring element.

[0031] The movement mechanism is designed to perform longitudinal discharge and retraction movements of the discharge element of the metering system, preferably at particularly high frequencies, in the metering direction or opposite to the metering direction, i.e., towards the bottom or towards the top in the case of normal arrangement. For this purpose, the discharge element can be structurally connected or coupled to the movement mechanism at the operating point (e.g., at the ram or ram head) or can be preloaded against it by a spring, for example a torsion spring, and can therefore simply be in a pressure contact state, for example. In any case, the coupling is performed in such a way that a tilting moment, typically a simple linear deflection or linear movement, generated by the actuator to expel the metering medium from the nozzle is transmitted successively or alternately from the lever via the contact surface of the lever to the discharge element (preferably the ram head of the ram) (during the discharge or retraction movement).

[0032] The spring element can be, for example, at least one pressure spring, which is preloaded with approximately 3-4 kN, i.e., it resiliently supports the movement mechanism against the frame housing unit. The two actuators are each preloaded or biased with, for example, 1.5-2 kN, preferably 1.8 kN. Suitable designs of the spring elements are described below.

[0033] The inventive structure of the subject of the present invention achieves that higher delivery frequencies of the metering system can be driven with consistently good metering accuracy and metering quality. Furthermore, the inventive structure makes it possible to dispense with dynamically stressed return springs in the two actuators, since these do not operate in a stable manner at all frequencies, which can lead to wobbling behavior or undesired vibrations of the system, especially in the case of rapid or high-frequency metering, as is actually desired in the present case.

[0034] Due to the overall elastic preloading of the motion mechanism relative to the frame housing unit, it is achieved that the mechanical vibrations remain within the mechanical system, and the overall elastic preloading is not a component of the mechanical system. Furthermore, individual thermal effects that may arise due to different local heating of the individual components of the metering system (piezoelectric actuator, frame housing unit, lever, etc.) do not have an individual effect on the distance between the dispensing element and the nozzle, as was previously the case in the prior art, but are largely compensated for. Therefore, the metering accuracy and metering quality of the overall metering system can no longer be significantly affected, at least by effects of this type.

[0035] The inventive structure of the subject of the present invention, in particular the tilted arrangement of the actuators in a common plane, further leads to a closer or closer positioning of the engagement points of the actuators on both sides around the center of rotation of the lever which in turn triggers the dispensing element via its lever arm for metering purposes. Thus, greater accelerations and therefore faster metering can be performed with the metering system according to the present invention, in that the lever can be designed to be smaller and lighter and therefore has a smaller moment of inertia.

[0036] A further advantage is that in particular the size of the droplets or the amount of medium per droplet can also be reduced even further. Thus, in the same time interval, larger surfaces can be wetted more by the metering medium. The structure according to the invention is particularly stable in contactless metering (thus in a microdosing manner) of small amounts of metered medium or substance onto a target surface with extremely precise accuracy and in contactless metering, i.e., metering without direct contact between the metering system and the target surface, i.e., during or by a jetting process.

[0037] Furthermore, certain advantageous designs and further developments of the invention are possible according to the following description and dependent claims, whereby individual features of different exemplary embodiments or alternatives can be combined into new exemplary embodiments or alternatives.

[0038] There are various options for increasing the dispensing frequency of a metering system: for example, the movement mechanism, in particular the lever, can be optimized or designed in an improved way.

[0039] The two actuators, which are arranged at an angle to one another, can generally be engaged on opposite longitudinal sides of the lever, for example at end portions of the lever arm of the lever, and for this purpose actuator engagement points can be formed on two opposite longitudinal sides of the lever.

[0040] The two actuators can preferably be located on a common longitudinal side of the lever so that they can engage with the lever from a generally common direction, and thus the first actuator engagement point and the second actuator engagement point can be formed and located on the same longitudinal side.

[0041] In the case of a normal arrangement of the weighing system (with a downwardly directed metering opening), the aforementioned longitudinal side is, for example, the top side extending in the longitudinal direction of the lever in the case of the exemplary embodiment described in detail later. Therefore, they exert a tilting moment on the lever in the opposite direction only, or alternately, on one longitudinal side of the lever, thus only stressing the lever on one side. Therefore, on the opposite (generally lower) longitudinal side of the lever, sufficient space is still available for the lever mount, ensuring a particularly space-saving and compact configuration of the weighing system as a whole. As already mentioned above, the arrangement of the actuator on one longitudinal side of the lever also allows the lever mount and the lever to be simultaneously supported against the actuator by a spring element, thus preloading the movement mechanism as a "dynamic" unit relative to the frame housing unit as a "static" unit in order to damp vibrations.

[0042] There are preferred options for the position of the actuators relative to the lever: for example, one actuator can thus be engaged perpendicularly to the lever, while the other actuator abuts the lever at an angle, so that the two actuators are in any case arranged at an angle relative to each other.

[0043] However, the actuators can preferably be arranged at the same angle relative to a common angle bisector or axis of symmetry (of an imaginary "V" of the actuators), the angle bisector or axis of symmetry being perpendicular to the top side of the lever. When viewed from a longitudinal side, the actuators can therefore be arranged in a V-shape so that they can be aligned by imaginary reflection relative to the axis of symmetry or relative to the angle bisector. When viewed spatially, as will be described later based on exemplary embodiments, the actuators can be arranged in a V-shape so that they can be aligned by imaginary reflection relative to the axes of symmetry that run perpendicularly and horizontally through the actuators, as well as to the aforementioned axes of symmetry.

[0044] The actuators can particularly preferably be arranged in such a way that the longitudinal direction of the lever or of the longitudinal axis of the lever lies in an imaginary plane spanned by the direction of action or the longitudinal axis of the actuator, or that the tilt axis of the lever is perpendicular to this imaginary plane. For practical purposes, the metering system can therefore be designed to be extremely flat (in a transverse direction perpendicular to the longitudinal direction of the lever), i.e. flat similar to the case of a -conventional- configuration in which only one actuator or two parallel actuators are installed, despite the fact that there are actuators arranged in an angle with respect to one another.

[0045] The actuators can be arranged in an angular range between two extreme positions - i.e., a parallel position extending next to each other on the one hand, and an opposite frontal position (i.e., a position when the actuators extend towards the lever from different sides and towards each other in a straight or common alignment) - and tilted relative to each other on the longitudinal sides of the lever symmetrically about a common angle bisector (excluding these extreme positions).

[0046] According to a preferred exemplary embodiment of the present invention, the actuators, more precisely their longitudinal axes or directions of action, can be arranged or positioned in a V-shape at an angle of at most or at most 150° relative to one another. More preferably, they can be arranged at an angle of at most 120°, or even more preferably at an angle of at most 90°, relative to one another. Particularly preferably, they can be arranged at an angle of at most 60°, and most preferably at an angle of at most 30°, relative to one another.

[0047] Angles smaller than 20°, in particular smaller than 10°, can then still be achieved by a correspondingly smaller cross section of the actuator or by correspondingly stretching and thinning the transducer of the actuator. In the case of an angle of 20°, "correspondingly smaller" means, for example, that half the cross section of each actuator may be less than 10°. On the other hand, the aforementioned stretching necessarily results in a significant expansion of the housing or of the weighing system, making the aforementioned structure larger and more susceptible to bending forces.

[0048] If the above-mentioned disadvantages are not relevant, it may nevertheless be desirable for the actuators to be arranged at an angle to one another, preferably at an angle of at most 20°, particularly preferably at an angle of at most 10°.

[0049] As is well known, the following applies: the more steeply the actuators are arranged relative to one another, i.e., the smaller the common angle between them, the greater the force transmitted to the lever, since the "more perpendicular" approximately adjacent to the lever or the lateral portion of the force is reduced. However, a steeper arrangement also ensures that the actuators must be moved further away from one another at the top or spaced apart, since due to their dimensions, in particular their lateral extension or their diameter perpendicular to their longitudinal axis, they interfere with themselves or with each other. Thus, as is the case disadvantageously in the prior art, the actuator engagement points are increasingly farther away from one another or from the tilt axis located between them in increasingly inclined positions, until in the parallel position they are separated from one another by at least the distance of their diameter based on their central longitudinal axis. In the case of a parallel arrangement of two actuators, the force arms of the actuators correspond to half the diameter of the actuators.

[0050] Due to the fact that the achievable mechanical energy in the case of piezoelectric actuators is a function of the volume of the actuator, i.e., its cross section or diameter, as well as its length, thinner actuators have a weaker force than thicker actuators of the same length. Furthermore, the thinner actuators are designed, the more unstable they become and the more unpredictable their behavior becomes (see also "rod buckling problem" or "bending strength"). Therefore, for the reasons mentioned above, it is not useful to use thinner and correspondingly longer actuators in order to reduce the force arm and increase the lever deflection.

[0051] This is because the further away or spaced apart the actuator is from the tilt axis when engaging the lever, the smaller the stroke or lever deflection that can be transferred or transmitted to the lever with a fixed stroke length related to the length of the actuator. This is because the stroke length of the actuator—in the case of a “stacked piezoelectric actuator,” a design in which the piezoelectric elements are stacked—is a function of its specific length (and therefore limited to a given length). With optimal selection of the position, and therefore the actuator engagement point where the actuator engages the lever, the possible deflection of the lever can be advantageously increased by the lever instead of the limited stroke length of the actuator itself, to achieve a stroke movement greater than the actual stroke length of the actuator. It is also true that the closer the engagement with the tilt axis, the greater the deflection of the lever, but also the greater the force required due to the shorter force arm.

[0052] The actuators can be positioned closer to the tilt axis by arranging them at an angle compared to arranging the two actuators in parallel, so that a larger deflection of the lever can be achieved - for the same embodiment of the actuator.

[0053] Actuators for metering systems can be realized in various ways, with piezoelectric actuators being preferred for applications requiring particularly sophisticated metering solutions. Compared to other types of actuators, such as hydraulic, pneumatic, and / or electromagnetic actuators, piezoelectric actuators, also referred to as piezo-electric actuators, have the advantage of high precision and particularly rapid controllability. Piezoelectric actuators are advantageously characterized by extremely short reaction or response times, which are usually significantly below the corresponding values ​​of other actuator principles. A further advantage is that, compared to other types of actuators, piezoelectric actuators require a relatively small installation space within the metering system. Piezoelectric actuators therefore provide an efficient solution for the operation of metering systems, particularly when extremely fine metering is required.

[0054] In the case of piezoelectric loaded actuators, it is a general fact that they can generate only fairly small strokes, but relatively large forces. For example, a 36 mm long piezoelectric load can achieve a stroke length of 50 μm. Therefore, it is generally necessary to convert the small stroke to a significantly larger one, whereby the force is obviously reduced accordingly.

[0055] Alternatively, the actuators can be magnetoresistive actuators, which utilize the principle that the dipoles of a ferromagnetic material will align identically, i.e., in a common orientation, when an external magnetic field is applied. By rotating the dipoles back to their original orientation, the length of the material changes as a function of the material, approximately in the range of a few μm / m to mm / m.

[0056] Therefore, the weighing system can preferably be configured so that the actuator engages as close as possible with the tilt axis to provide the maximum possible deflection of the lever. Due to the fact that the force of the actuator is consequently reduced and one power enters the force arm at the time of actuation—thus creating a disadvantage for dynamic applications, for example, when the weighing system is dynamically moved relative to a workpiece in a weighing plant for weighing purposes—it is advantageous to design the size of the lever or the general dimensions of the lever to be as small as possible to obtain a fast weighing system. This is because, due to conservation of angular momentum, a lever with a smaller mass moment of inertia can be "rotated" or moved back and forth about the rotation or tilt axis faster than a lever with a larger mass moment of inertia.

[0057] Due to the fact that the mass moment of inertia due to the two powers is a function of the distance of the mass point (of the lever) to the center of rotation or to the tilt axis, it increases disproportionately with the length of the lever (and therefore with the distance of the mass point from the center of rotation).

[0058] According to the invention, in that the actuators are arranged at an angle to one another, for a given conversion ratio (force relative to the force arm), the mass moment of inertia of the lever can also be smaller, since the distance of the force arm to the center of rotation or the length of the force arm is thus smaller, which in turn results in the formation of a smaller lever. A smaller lever, and therefore a smaller mass moment of inertia, therefore ultimately results in a higher resonant frequency of the weighing system with actuators arranged at an angle to one another than in the case of a system with parallel actuators of the same design.

[0059] It is therefore advantageous to center the mass more closely to the tilt axis for faster movement of the lever.

[0060] The lever can therefore preferably have a non-uniform mass distribution, where "non-uniform" means that the mass of the lever is neither symmetrically nor uniformly distributed over its length in the longitudinal direction, but that the lever is configured asymmetrically at least in its mass.

[0061] The mass of the lever can particularly preferably also be distributed along the lever with respect to the tilt axis in such a way that the entire lever has the smallest possible (mass) moment of inertia based on the tilt axis. During the configuration, it is also preferably ensured that as much mass as possible is located close to the center of rotation and as little mass as possible is located away from the center of rotation, thus resulting in an elongated arm towards the discharge element.

[0062] However, the weight of the lever can preferably be reduced or distributed relative to the center of rotation in such an amount that it still has a sufficiently high stability, e.g., allows the lever to oscillate particularly quickly. In top view, i.e., when viewed from above, the lever can, for example, be formed with a generally "spoon-shaped" profile, with the major part of its mass close to the center of rotation being located in an "oval" or "round" section around the center of rotation.

[0063] The lever preferably has a number of recesses, particularly preferably through-holes extending transversely or laterally of the lever, in order to reduce its weight.

[0064] The actuator engagement points with the levers of the actuators can preferably be neither located nor positioned in the horizontal plane of the tilt axis, which therefore means that they are not located in the same plane as the tilt axis in which it actually lies.

[0065] In particular in dynamic cases (e.g. when a weighing system in a weighing plant is dynamically moved relative to a workpiece for weighing purposes), when the lever is tilted by a tilting moment of the actuator by an angle of several degrees around the tilt axis, it is advantageously achieved by arranging the actuator engagement point on the lever outside the plane that the actuator only makes as small a lateral or shear movement as possible perpendicular to the direction of action of the actuator when a tilting moment (in the form of a longitudinal deflection) is applied to the lever.

[0066] This is because in the case of larger lateral movements, and therefore a directional or lateral component transverse to the direction of action, a significant arching pendulum movement of the actuator along a circle around the pivot or tilt axis through the two actuator engagement points of the actuator on the lever results in a response to an actual linear deflection in the direction of action. The pendulum movement becomes more linear with the reduction of the lateral component. It is avoided, if possible, that actuators with very large masses actually swing perpendicular to the direction of action while they are deflected longitudinally in the direction of action, thus resulting in undesirable vibration effects and / or greater wear of components, in response to their longitudinal deflection in the direction of action.

[0067] The actuator engagement point may generally be formed above the tilt axis of the lever, for example directly on the top surface of the lever, so that the actuator engages the lever there.

[0068] To enable the actuator engagement points to be positioned even closer to the tilt axis when the actuators are tilted relative to one another, the levers can be formed and positioned such that the two actuator engagement points are located or recessed in the lever further away from the top or longitudinal side of the lever facing the actuator than the tilt axis along which the lever is rotatably or tiltably supported on the lever mount as described above. "Further away from the top or longitudinal side of the lever facing the actuator" means that the actuator engagement points are located further away from the piezoelectric element of the actuator or deeper in the lever than the tilt axis when the lever is positioned as intended on the lever mount. The actuators are therefore positioned such that they extend first through the tilt axis at their front or tip and therefore engage or contact the lever only at actuator engagement points formed below the actual tilt axis in a recessed manner, passing through or extending through the horizontal plane of the tilt axis.

[0069] The respective actuator engagement points of the two actuators can therefore be arranged parallel to a common tilt axis in the same or similarly offset manner. In the case of alternative preferred exemplary embodiments, the actuators can also act on actuator engagement points of levers that are laterally or longitudinally parallel offset.

[0070] The actuators arranged on or abutting the levers in a V-shape are preferably aligned with or engageable with the actuator engagement points such that, in the horizontal center position of the levers, the longitudinal axes of the actuators are approximately perpendicular to the respective connecting lines between the respective actuator engagement points and the common tilt axis.

[0071] That is, the actuators are therefore engaged with offset actuator engagement points on a connecting line perpendicular to the tilt axis. The center position of the lever corresponds to the position or configuration of the lever when the lever is horizontal and both actuators are unpowered or de-energized.

[0072] In order to keep as small as possible the lateral or pendulum movement of the actuator along the length of the circle or arc of a circle along which the actuator engagement point is moved or displaced when the actuator moves back and forth, i.e. when the piezoelectric element expands or contracts, the actuators can V-engage with the actuator engagement points of the lever in a manner such that their direction of action extends past the tilt axis and in which they are tilted and arranged, such that their direction of action is tangent to a circle around the central tilt axis of the lever passing through the two actuator engagement points of the actuators on the lever (or perpendicular to the joining line from each actuator engagement point to the tilt axis, in particular to the surface of the cylinder pin that forms the tilt axis, as will be described later in the exemplary embodiment).

[0073] In this respect, it should be noted that, from a microscopic perspective, the central axis of the cylinder pin does not perfectly represent the tilt axis, but rather the connection between the slightly larger, cylindrically concave outer surface of the lever, which is pressed tangentially against each other and therefore undergoes minimal rotational movement on the outer surface of the cylinder pin (which is rigidly attached at its underside to the lever mount), and the outer surface of the lever, which, when tilted, undergoes minimal rotational movement on the outer surface of the cylinder pin. A perfect tilt axis therefore does not exist in this sense, but the movement is more complex. However, the central axis of the cylinder pin can here be roughly, approximately, identified with the tilt axis, at least in the case of a microscopic perspective.

[0074] That is, the actuator can preferably be arranged tangentially on a circle around the tilt axis at the actuator engagement point so that it performs a substantially linear movement during the operation for metering the metering medium in response to the dispensing and retracting movements. "Substantially" means that the actuator performs a linear movement during the dispensing and retracting movements without any significant lateral movement on the circle due to pendulum movement. As already mentioned above, tangential arrangement means that the longitudinal axis or direction of action of the actuator is tangential to the actuator engagement point on the circle around the tilt axis.

[0075] There are further design options for the metering system.

[0076] The lever mounting unit may preferably be of multi-part construction.

[0077] In addition to the lever mount already described, it is particularly preferred to provide a fluid positioning element for a hydraulic unit of the metering system, which hydraulic unit can be connected to the lever mounting unit.

[0078] The lever mount can be rotatably, articulably or tiltably connected to the fluid positioning part particularly preferably via a rotary joint located outside the frame housing unit.

[0079] Alternatively or additionally, the lever mount and the fluid positioning part can be supported in a mechanically adjustable manner relative to one another, and thus in a rotatable or tiltable or shiftable manner, for example by means of an angular adjustment element relative to the rotary joint.

[0080] The lever mounting unit may preferably have a ring structure that annularly surrounds a portion of the frame housing unit by leaving at least one gap. As usual, a "gap" is understood herein as a narrow, elongated opening that forms an intermediate space. A "ring structure" or "annular" refers to a structure of two components that are formed or set in an annular shape, i.e., structurally designed. A ring structure thus specifies a ring-shaped structure or a ring-shaped arrangement when two components can be combined in an annular shape to form a closed ring. The portion of the frame housing unit may be, for example, the housing bottom of the frame housing unit.

[0081] The lever mounting unit can particularly preferably be movably supported on the frame housing unit by means of a spring element which is preferably arranged in the gap between the lever mounting unit and the above-mentioned part of the frame housing unit.

[0082] Alternatively or additionally, the ring structure may comprise a rotary joint, which may be the rotary joint described above when the weighing system is configured as described above.

[0083] The lever mount of the lever mounting unit can be connected to the fluid positioning part via a lever or ram in a way that is mechanically adjustable relative to itself (by leaving at least one gap relative to the frame housing unit so as to annularly surround the spring element in the ring structure of the lever mounting unit) for adjusting the ram-nozzle distance on the side of the fluid positioning part remote from the rotary joint by means of an adjustment element (in particular an adjustment screw). The adjustment screw can, for example, be a finely threaded screw, which allows the position of the ram at the nozzle, i.e. the ram-nozzle distance, to be fine-tuned or adjusted even more completely.

[0084] "Far from the rotary joint" as used herein means the portion of the fluid positioning section (from the rotary joint to the ram) that is located on the ram half across the center of the fluid positioning section, and therefore as close as possible to the ram.

[0085] Despite the above-mentioned advantages associated with piezoelectric actuators, they are components in which large power losses can be converted to cause strong heating of the piezoelectric material, which itself has a thermal limit due to its specific Curie temperature, as well as the respective contacts of the electrodes.

[0086] In order to be able to further prevent heating of the movement mechanism, and in particular heating of the piezoelectric actuators, both piezoelectric actuators can be designed with compressed ambient air or compressed air flowing all around them, since compressed air is already available in most metering system plants.

[0087] For example, if this compressed or pressurized air is unable to dissipate enough heat from the piezoelectric actuator due to higher ambient temperatures in the area where the metering system is applied, a cooling device through which a gas, preferably air, or liquid flows can preferably surround the actuator to keep the piezoelectric actuator, as well as other temperature-sensitive areas of the metering system, below temperatures critical for the correct operation of the metering system at all times.

[0088] The cooling device may preferably have a supply channel between the actuators with multiple inlets into the actuators and two eccentric drain channels with multiple outlets into the drain channels. The cooling device may be formed as a mostly closed circuit, i.e. a cold cooling flow is introduced into the metering system which absorbs heat reducing the temperature of the movement mechanism and is substantially discharged again from the metering system.

[0089] Back pressure in the cooling device can be reduced by this embodiment of the cooling device, which has two exhaust channels and a supply channel. The supply channel can, for example, extend centrally and substantially parallel to the actuator. However, it can preferably be integrated into a frame housing unit that surrounds the actuator. The two exhaust channels can be formed and arranged on the outside of the actuator facing away from each other, opposite the supply channel, so that the cooling flow can be very easily guided continuously past the actuator during operation to absorb heat.

[0090] The lever and lever mount of the movement mechanism do not flow separately for that matter, but only the waste heat of the piezoelectric actuator can flow around, for example.

[0091] According to a preferred design of the present invention, the actuator may further be formed in an encapsulated manner, for example the actuator may be operatively encapsulated with sufficient play in a substantially cylindrical encapsulation.

[0092] A cooling flow that flows around the encapsulations parallel to their longitudinal extension can therefore be applied to the actuators, for example the cooling medium of the cooling flow can be a gas, for example air, nitrogen, etc., but also a liquid or viscous liquid, for example a cooling liquid, provided that it has a flow rate high enough to remove the heat of the encapsulated actuators.

[0093] It is likewise conceivable that the gap or intermediate space between the encapsulated actuator and the housing is filled with a preferably soft but heat-conducting mass, so that the waste heat of the actuator can be released directly into the frame housing unit and out to the environment via the outer surface or in an enhanced form by forced convection, for example by a ventilation device.

[0094] Alternatively or additionally, the actuator may be provided with at least one temperature sensor to measure or monitor heating of the actuator and selectively adjust the operating speed accordingly to reduce heating of the component during operation. If an enclosure is present, the temperature sensor may be located inside or outside the enclosure. The position of the ram at the nozzle of the valve chamber or nozzle chamber can be fine-tuned if necessary and preferably automatically controlled by the measured temperature data of the temperature sensor so that, depending on which of the above-mentioned methods is used, in the center position of the lever, the ram always either completely closes the nozzle of the valve (tip of the ram in the closed position) or the nozzle is now open (tip of the ram away from the nozzle) in response to changed temperature.

[0095] The connection between the movement mechanism and the ram can preferably be a lockable connection, which means that the two components are preferably connected to each other in a positively locking manner for operation (e.g. screwed, clicked together, latched, etc.), in addition to a preload that is particularly preferably already in continuous contact with the components.

[0096] With the components fixedly connected thereto, the frame housing unit preferably forms the "first main mass" of the weighing system, as described above. With the actuator, lever and lever mounting, the motion mechanism preferably combines a second main mass as part of the overall mass of the weighing system, i.e. forms (e.g. in selective combination with further components such as a fluidic unit) the "second main mass" of the weighing system.

[0097] In order to improve the general weighing results or to quiet the dynamic components of the weighing system, the main mass of the weighing system can be divided approximately uniformly, i.e. into approximately equal parts, relative to the frame housing unit and the lever mounting unit. A purposeful distribution of the total mass of the weighing system relative to two "main masses" of approximately the same size ensures that the entire system, which is coupled in an oscillatory manner, does not respond to high-frequency vibrations of the kinematic mechanism.

[0098] To elastically support the movement mechanism as a whole relative to the frame housing unit, the spring elements can preferably be a set of disc springs. The set of disc springs particularly preferably comprises a plurality of single spring leaves and / or a plurality of spring sets. Different single spring leaves and / or spring sets can also be realized to be combined to form a set of disc springs. For example, to compensate for thermal behavior, such as temperature-related deformations of the actuator, the movement mechanism can thus be preloaded by the set of disc springs.

[0099] The invention will be described again in more detail below on the basis of exemplary embodiments and with reference to the accompanying drawings, in which the same components are given the same reference signs in the various figures, and in which the figures will generally be understood as schematic representations and not as to scale. [Brief explanation of the drawings]

[0100] [Figure 1] 3 shows a partial longitudinal section (along the AA section line according to FIG. 2) of an exemplary embodiment of a metering system according to the invention, looking into the interior of the housing of the metering system; [Figure 2] 2 shows a top view without the housing on the exemplary embodiment from FIG. 1 for better overview and understanding. [Figure 3] 2 shows an enlarged isolated plan view on the lever of the exemplary embodiment from FIG. 1; [Figure 4]4 shows a longitudinal section along the line BB through the lever of FIG. 3. [Figure 5] 2 shows an enlarged, partially transparent perspective partial view of two actuators abutting the lever of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0101] FIG. 1 shows an overall view of a first exemplary embodiment of a metering system 1 according to the invention for metering a metering medium onto a workpiece in a partial longitudinal section through the metering system 1 along the AA section line, which extends at least primarily longitudinally through the metering system 1 in a longitudinal direction 30L (horizontally or side-to-side in FIG. 1). This AA section line is shown in FIG. 2 in a plan or top view on the metering system 1. It extends centrally through the metering system 1 (in particular through the lever 30 of the metering system 1) but jumps into an eccentric parallel cross-sectional plane in the region of the lever 30 between two so-called actuator engagement points 36 and 37 of two actuators 50a, 50b on the lever 30 in a transverse direction 30Q of the lever 30 (extending into the plane of the paper in FIG. 1 and upward in FIG. 2). At least one of two distributed cylinder pins 42 (see FIG. 5) forming the rotation or tilt axis R of the lever 30 of the metering system 1 is visible. The remaining directions of the weighing system 1, which extend vertically in FIG. 1, are also embodied below as coincidences with the depth direction 30T of the lever 30. In this direction, the axis or axis of symmetry S shown in FIG. T is this axis S T Extending centrally between two actuators 50a and 50b arranged at an angle relative to each other or to each other, an axis of symmetry S T The tilt axis R is inserted perpendicularly into the symmetry axis S. T extends into the plane of the paper in FIG. 2. The horizontal axis or axis of symmetry S Q is the vertical symmetry axis S of the actuators 50a and 50b. T 2 herein from top to bottom or vice versa. T and SQ are both symmetric planes S Q , S T , with respect to which plane of symmetry the actuators 50a, 50b together form a symmetrical "V". Apart from that, the already mentioned AA section line is Q , S T It extends vertically through the weighing system 1.

[0102] In addition to the static frame housing unit 2, which primarily surrounds the metering system 1 on all sides, the main components of the present invention also include the dynamic movement mechanisms 3, 4, 5, 30, 50a, 50b (i.e. the lever mounting unit 3 with the lever mount 4 and the fluid positioning part 5, the lever 30 already mentioned above, and the two actuators 50a, 50b), the spring element 21 formed as a disc spring 21 which supports or preloads the dynamic movement mechanisms 3, 4, 5, 30, 50a, 50b against the static frame housing unit 2, as well as a fluid unit 8 which can be connected to the fluid positioning part 5 (described further below) of the lever mounting unit 3, for example comprising a valve unit 9 in contact with the lever 30 and which has a nozzle 12 for metering metering medium in the metering direction DR (here downwards). For better distinction or separation, in FIG. 1 the static frame housing unit 2 is shaded from top left to bottom right, while the dynamic motion mechanisms 3, 4, 5, 30, 50a, 50b, excluding the two actuators 50a, 50b, are shaded from bottom left to top right.

[0103] The lever mount 4 is a part of the at least two-part lever mounting unit 3 of the metering system 1 that is located inside the frame housing unit 2. The fluid positioning part 5 is a part of the lever mounting unit 3 that is located outside the frame housing unit 2. The two parts 4, 5 are rotatably connected to each other, for example via a rotary joint 6 outside the frame housing unit 2. The substantially elongated fluid positioning part 5 extends from the rotary joint 6 (to the right, below the frame housing unit 2 in FIG. 1 ) at a distance from the rotary joint 6, parallel to the frame housing unit 2 or parallel to the preferably detachably connectable housing bottom 2′ of the frame housing unit 2 (and therefore parallel to the lever mount 4 that is elastically supported inside the frame housing unit 2), and can be pulled relative to the lever mount 4 by an adjustment element 7 (here, an adjustment screw 7) to adjust the preload of the discharge element 13 (here, the ram 13). The two above-mentioned parts 4, 5 together form a kind of ring structure or ring that engages around or surrounds the above-mentioned housing bottom 2' and spring element 21 of the frame housing unit 2 in a ring-like manner (as will be described later).

[0104] The valve unit 9, already mentioned above, is inserted between the end portion 33 of the lever 30 and the fluid positioning element 5. The valve unit 9 comprises a hollow cylindrical valve body 10 in which the ram 13 is movably guided. A tappet spring 15 is arranged between the valve body 10 and the end ram head 14 on the end of the ram 13 opposite the ram tip 16, so that the ram 13 is elastically supported. The distance between the nozzle 12 and the end portion 33 of the lever 30 can therefore be varied by means of an adjusting screw 7, which is provided for complete adjustment of the ram end position based on the nozzle insert 12' and therefore for secure closure of the metering system 1. The adjusting screw 7 has a finely threaded screw equipped with a compression coil spring, which allows fine adjustment of the distance between the lever mount 4 and the fluid positioning element 5. The adjusting screw 7 therefore ensures perfect adjustment of the metering system 1 to the characteristics of the nozzle 12 and the ram 13, thereby compensating for possible manufacturing tolerances or wear.

[0105] In the region of the valve unit 9, the fluid positioning part 5 further comprises a heating device which is integrated in the fluid positioning part 5 and which is supplied and regulated by the electronics of the valve unit 9. The heating device itself comprises a heating cartridge and a sensor, if necessary, in order to heat or warm the metering medium for metering.

[0106] In addition to the above-mentioned valve unit 9, the fluidic unit 8, which is detachably connected to the fluid positioning part 5, comprises a metering medium supply connection 17, which fully and continuously supplies or conveys metering medium to the metering system 1 from a storage container 17r, for example a metering substance cartridge 17r in this embodiment, into the valve chamber 11. A medium supply channel or medium conveying channel (not shown) is located internally between and extends to the metering medium supply connection 17 and the valve chamber 11.

[0107] As can be seen in FIG. 1, the fluidic unit 8 also includes a heating device, i.e., a heating unit 18 with a second heating zone along the medium-carrying channel and a heating element 20 in the nozzle region or on the nozzle chamber 11 of the lever unit 9. For this purpose, the heating unit 18 is supplied via a connection 19 or a heating cable 19. However, in the case of a completely passive fluidic unit that is neither heated nor regulated itself, temperature control in the nozzle region is possible. In particular, temperature control of the medium-carrying channel can also be carried out using this, which results in improved preheating of the metering medium, which is particularly advantageous in the case of large volume flows.

[0108] The fluid unit 8, already mentioned above, is removably mounted on the boundary surface 5s of the fluid positioning part 5, away from the rotary joint, near the heating element 20, and has a medium supply channel from the metering medium supply connection 17 to the valve chamber 11 of the valve unit 9 in order to continuously guide the metering medium from a storage container 17r, for example here a metering substance cartridge 17r, via the metering medium supply connection 17 and the medium supply channel into the valve chamber 11.

[0109] During operation, the metering system 1 partially applies the desired metering medium from a reservoir 17r in the nozzle 12 of the valve chamber 11 to the workpiece. For this purpose, at least droplets of the desired metering medium or of the substance to be metered, the amount of which can be completely metered, are released in the metering direction DR through the opening cross-section of the nozzle 12 or the opening cross-section of the nozzle insert 12' in the nozzle 12 during metering. This is indirectly controlled via the lever 30 by the rapid movement of the ram 13 or the ram movement 30B and can be driven by actuators 50a, 50b operating in diametrically opposed ways. The changeable nozzle insert 12' in the nozzle 12 of the valve chamber 11 serves the purpose of being able to adjust the metered amount and the shape of the droplets, more particularly for different fields of application.

[0110] The remaining components within the frame housing unit 2 will now be described below.

[0111] The spring element 21 (already mentioned above) supporting the movement mechanisms 3, 4, 5, 30, 50a, 50b in the frame housing unit 2 rests on its bottom against the housing bottom 2' of the frame housing unit 2, thereby supporting the lever 30, which is rotatably supported on the lever mount 4 about the rotation axis R, against the upper part of the frame housing unit 2 or the frame via the two actuators 50a, 50b that rest near the tilt axis R against the lever 30. The support applies a preload via the lever mount to the two piezoelectric actuators required to avoid tensile stresses during dynamic operation. Due to the relatively inert mass of the frame housing unit 2, dynamic vibrations are simultaneously strongly damped, and temperature differences or temperature gradients resulting from the dynamically operating movement mechanisms 3, 4, 5, 30, 50a, 50b are decoupled from the frame housing unit 2 of the metering system 1 and coupled or equalized to the valve unit 9. These effects therefore have practically no influence on the metering process of the metering medium from the nozzle 12 of the valve unit 9. In the exemplary embodiment described herein of the metering system 1 according to the invention, the spring element 21 is a set of disc springs 21, for example comprising four single leaf springs supported vertically one above the other and elastically supported one below the other, the spring forces of which combine. Such a structure is compressed flat and provides high damping of the set of disc springs, thus also reducing the tendency of the frame housing unit to vibrate relative to the lever mounting unit.

[0112] As already mentioned, the spring element 21 is connected (here, by screw connection) at its underside to the housing bottom 2' (e.g., metal sheet, plate, etc.) of the frame housing unit 2. It is therefore firmly connected to one side (here, the underside). However, alternatively, the spring elements can simply be fastened with fasteners between them.

[0113] The housing bottom 2' in Figure 1 has notches to the right and left (towards the side or towards the bottom) of the set of disc springs 21 so that the two parts 4, 5 can be supported against each other in the shape of a ring or annularly around or around the set of disc springs 21, spaced apart from or with a spacer gap from the housing bottom 2'.

[0114] The lever mount 4 rests on the spring element 21 at its top side and is pressed against the spring element 21 by the actuators 50a, 50b as described above.

[0115] The lever mount 4 has two lateral "legs" (one behind the other, as viewed in FIG. 1 ) with a semicircular recess open to the top. An interior is formed between these legs to accommodate the lever 30 with the necessary freedom of movement. Only one of the two legs of the lever mount 4 is visible in the side view according to FIG. 1 because, viewed from this direction, they are located one behind the other. One of the two cylinder pins 42 (see FIG. 5 ), which forms the axis of rotation R, can be seen in a recess in the visible leg (here the front leg). To better identify the configuration of this part of the weighing system 1, a BB section (in the form of a single square pulse) extending longitudinally through the lever 30 in FIG. 3 is shown in isolation, and uses the same course of section as that used by the AA section in FIG. 2 already described above.

[0116] As can be seen in Figure 5, each of the cylinder pins 42, with respect to its outer half portion 42a (along the cylinder pin axis), rests approximately laterally on one of the legs of the lever mount 40, and with respect to its other inner half portion 42b, simultaneously holds the lever 30 (so that it can rotate around itself) inside the lever mount 40. For this purpose, the cylinder pins 42 protrude into lateral recesses 41 (described further below) of the lever 30 that are formed laterally (in the lateral direction 30Q) in the lever 30 and that are U-shaped and open at the bottom (closed at the top), the lateral recesses 41 being indicated by dashed lines in the top view of the lever 30 in Figure 3 and shown from the side in Figure 4.

[0117] The shape of the lever 30 can be depicted graphically as a two-way, three-dimensional, asymmetrical force transducer in the style of a "barrier beam" (with a counterweight). Specifically, the lever arm 31 of the lever 30 comprises a massive, voluminous, approximately cubic section in approximately one half of its longitudinal direction 30L, and a narrow, elongated handle or "arm" in the other half, designed to be as lightweight as possible. One half of the cubic section (the right side in FIG. 3 ) belongs to the shorter lever arm side 32 of the two-sided lever arm 31. The other half of the cubic section (the left side in FIG. 3 ), together with the elongated arm connected to it, belongs to the longer lever arm side 35 of the two-sided lever arm 31. The rotation axis R of the lever 30 is located between them, next to which the two actuators 50a, 50b of the movement mechanisms 3, 4, 5, 30, 50a, 50b engage with actuator engagement points 36, 37 on the lever 30. The first actuator 50a (left) engages with a first actuator engagement point 36 (left) on the first lever arm side 35 of the two-sided lever arm 31, which is recessed or concave within the interior of the lever 30, and the second actuator 50b (right) engages with a second actuator engagement point 37 (right) which is equally recessed or concave on the second lever arm side 32 of the two-sided lever arm 31 (see also Figures 3-5 for the locations of the actuator engagement points 36, 37).

[0118] In the normal configuration of the weighing system 1, as shown in Figure 1, the two actuators 50a, 50b directly abut the lever 30 on the top side 40 of the cubic portion (on the top in the depth direction 30T in Figure 1, on the cylinder pins 36z, 37z of the actuator engagement points 36, 37 described below).

[0119] On the basis of the lever 30 shown partly in perspective in Fig. 5 and on the basis of parts of the two actuators 50a, 50b, how exactly the two actuators 50a, 50b or their front parts 54 thereof engage or abut with the lever 40, i.e. how they transmit a tilting moment or longitudinal deflection in their action directions 52a, 52b to the lever 30 in order to achieve a targeted tilting of the lever 40 by an angle of a few degrees around the rotation axis R or tilt axis R, is shown. As can be seen from the enlarged portion in Fig. 5, the actuators 50a, 50b abut tangentially in their action directions 52a, 52b on the circle K of the aforementioned engagement points (or actuator engagement points 36, 37), so that the action directions 52a, 52b are perpendicular to the radial connecting lines Va, Vb of the common rotation axis R at the centre of the circle K. Due to the fact that the actuation axes 52a, 52b engage the circle K in a tangential direction, longitudinal deflection of the actuators 50a, 50b, i.e., tilting moment of the actuators 50a, 50b, such that their front ends 54 move minimally with the lever 30 in an arc around the rotation axis R (around the tangential or central position P0 of the lever shown in FIG. 5) by an angle of a few degrees toward the bottom or top, produces only minimal lateral movement. If the actuators 50a, 50b or their actuation axes 52a, 52b, respectively, were engaged further along the circle K at the top or bottom, the same deflection of a few degrees along the circle K would cause significantly greater lateral movement of the front ends 54 of the actuators 50a, 50b. The movement along the circle K or in an arc-shaped path or pendulum movement can be reduced as much as possible in a straight longitudinal direction by the tangential arrangement of the actuation axes 52a, 52b on the circle K around the rotation axis R.

[0120] On its underside (at the bottom of the depth direction 30T in FIG. 1 ), the lever 30 indirectly abuts against the lever mount 4 at the rotation axis R between the actuator engagement points 36, 37 in the cubic part (by the outer half 42a of the cylinder pin 42) and contacts the ram head 14 of the ram 13 at the end part 33 of the elongated arm. A further hole 34 is formed in the lever 30 in the end part 33 of the arm of the lever 30. It serves for the introduction of a permanent magnet and therefore for the positioning of the lever 30 by a HALL sensor fastened to the lever mounting unit 3.

[0121] The actuators 50a, 50b are first aligned with the plane X of the rotation / rotation axis. R 1 ), lever 30 has wedge-shaped recesses 39 tapering downwardly therein that begin on top side 40 and extend to actuator engagement points 36, 37 on the interior of lever 30 below the top side 40 (and not yet on the surface on top side 40 of lever 30). The lowest points or locations of the wedge-shaped recesses 39 on lever 30 define first actuator engagement point 36 for first actuator 50a (the left actuator in FIG. 1 ) and second actuator engagement point 37 for second actuator 50b (the right actuator in FIG. 1 ). The wedge-shaped recess 39 is formed in such a way that the front or tip portions 54 of the actuators 50a, 50b, which are arranged at an angle to one another and which are similarly tapered in a wedge shape when the weighing system 1 is assembled as intended, are received therein with space or play on the other side.

[0122] As can be seen in particular in Figure 5, the actuator engagement points 36, 37 structurally consist of the two cylinder pins 36z, 37z already mentioned, on which the actuators 50a, 50b abut via their front parts 54 and can roll on the cylinder pins 36z, 37z. At the front, the abutting front sides of the front parts 54 of the actuators 50a, 50b are recessed into the cylinder pins 36z, 37z with a relatively slightly larger radius. For this purpose, a core hole is formed across the lever 30 so as to be continuous in the transverse direction 30Q from one longitudinal side of the lever 30 to the other, is substantially completely filled by the cylinder pins 36z, 37z (see Figure 5), and intersects with the edge region of the wedge-shaped recess 39, so that in cross section the core hole opens to the top towards the wedge-shaped recess 39. The radius of the core holes is adapted to the cylinder pins 36z, 37z, so that a stable hold is ensured and the actuators 50a, 50b ensure low-friction relative rotational movement with their front parts 54 on the fixed cylinder pins 36z, 37z.

[0123] The recess 41 for the other cylinder pin 42 already mentioned above, by means of which the lever 30 is actually supported tiltably about the rotation axis R inside between the two legs of the lever mount 4, is, as already mentioned above, located obliquely between the aforementioned core holes and centered in the longitudinal direction 30L. The radius of the recess 41 is also slightly larger than the radius of the cylinder pin 42, so that a "fixed" target position is likewise present and a low-friction relative rotational movement is guaranteed. In the transverse direction 30Q, the recesses 41 are located opposite each other and are spaced apart from each other, starting outside the wedge-shaped recess 39 in the edge region of the lever 30 (see FIG. 3). In the depth direction 30T of the lever 30, they are aligned with the so-called engagement axis plane X of the lever 30. A (See FIG. 4.) By definition, the engagement axis plane X Ais tensioned or formed by the actuator engagement points 36, 37 located on the surfaces of the cylinder pins 36z, 37z. At the center position P0 of the lever 30, the engagement axis plane X A are aligned horizontally. The cylinder pins 42 are received (as can be seen in FIG. 5) over approximately half their length by the inner half 42b in the recess 41 (where they abut at or against the top side, as mentioned above), and in the recess of the lever mount 4 which opens at the top in the shape of a semicircle, with their underside on the leg, together with the other outer half 42a, making it very easy to insert the lever 30 from the top into the lever mount 4 during assembly to reach this operating state before further components are attached or installed.

[0124] In operation, the lever 30 is arranged on or in the lever mount 4 in a very space-saving manner overall, since it projects into or is received between the legs of the lever mount 4 with just enough play in its depth direction 30T, approximately halfway up its height or depth. This type of support allows it to be tilted as defined about the tilt axis R by an angle of at least a few degrees (i.e., preferably between + / - 0.1° and + / - 5°) without coming into direct contact with the lever mount 4. In this regard, a tilt angle of + / - 0.5° is particularly preferred. Its rotation axis R, which extends laterally across the lever 30, extends eccentrically from its center of gravity in the longitudinal direction 30L.

[0125] In order to reduce the weight of the lever 30 (especially its longitudinal arm), the lever 30 has, if possible, four holes 38 or recesses 38 in addition to a closed wedge-shaped recess 39 in the arm (left side in FIG. 4 ). The holes 38 are circular and of different sizes, their diameter decreasing towards the end portion 33 because they are adapted to the shape of the lever 30, which as a whole becomes flatter towards the end portion 33. They are each slightly spaced apart from one another and each extend continuously through the lever 30 in the transverse direction 30Q. The holes 38 functionally ensure a maximum weight reduction of the lever 30 without adversely affecting its stability. The above-mentioned term "becoming flatter" means that, starting from the wedge-shaped recess 39 closed to the above-mentioned arm, the lever 30 has an underside that extends in the longitudinal direction 30L towards the end portion 33 at an angle to the top side 40, and therefore the lever 30 becomes shallower or flatter in the depth direction 30T. The end portion that is in contact with the ram head 14 and that is located at the end of the elongated arm in the central position P0 of the lever 30 is therefore located at exactly the same height as the upper end of the recess 41 in the lever 30 for the above-mentioned cylinder pin 42 in the voluminous part of the lever 30. In other words, the end portion 33 of the lever 30 in the central position P0 is therefore located at exactly the same height as the upper end of the recess 41 in the lever 30 for the above-mentioned cylinder pin 42 in the voluminous part of the lever 30. R Located just at.

[0126] For this purpose, a lever mount end (not shown for clarity) can (but is not required to) be attached to the lever mount 4 at the top as an upper end that at least surrounds the cylinder pin 42 to the top, or as a partially open cover with holes for the actuators 50a, 50b. In order to substantially completely surround or enclose the lever 30 from the top, such a lever mount end can have approximately the same size and shape as the lever mount 4 below. It can have through-holes for the actuators 50a, 50b that extend obliquely from top to bottom to be able to engage with the actuator engagement points 36, 37 on the lever 30, through which the actuators 50a, 50b extend with their cylindrical transducers 53 (in the acting directions 52a, 52b behind the fronts 54 of the actuators 50a, 50b). The lever mount 4 and its upper lever mount end provide for the lever 30 to be largely shielded from the rest of the weighing system 1 and operatively supported therein.

[0127] are arranged at an angle to each other and have an axis S T Positioned above the lever 30 are two actuators 50a, 50b that are aligned symmetrically with respect to the lever 30 and that, as described, abut at their recessed tip or front portions 54 against the cylinder pins 36z, 37z of the actuator engagement points 36, 37 on the lever 30.

[0128] The two similarly configured actuators 50a, 50b, or piezoelectric actuators 50a, 50b, are typically several piezoelectric elements 51 or "piezoelectric plates" stacked together to form a piezoelectric stack, and the movement of the mechanism is generated by the piezoelectric elements 51 in the longitudinal or acting direction 52a, 52b of the actuators 50a, 50b, i.e., normal to or perpendicular to the surface of the piezoelectric elements 51 along the longitudinal axes 52a, 52b of the actuators 50a, 50b, respectively, by applying an electric current through the so-called "inverse piezoelectric effect".

[0129] The encapsulated actuators 50a, 50b are embedded in recesses 56 in the frame housing unit 2 that are sealed around the piezoelectric element 51 by O-rings 57, and are cooled during operation within the recesses 56 in the frame housing unit 2 with the aid of a cooling device 60 of the metering system 1 integrated into the frame housing unit 2.

[0130] The cooling device 60 or cooling channel system 60 comprises a supply channel 61 for introducing a cooling medium centrally between the actuators 50a, 50b for cooling the piezoelectric elements 51, and two discharge channels 63a, 63b (left and right in FIG. 1 ) next to the piezoelectric elements 51 or actuators 50a, 50b for parallel and continuous repeated discharge of the cooling medium laterally in the longitudinal direction 30L. From a supply source connected to the metering system 1 on the upper part of the frame housing unit 2 or on the frame, the cooling medium flows in a cooling flow direction 60i (directed downwards in FIG. 1 ) into the supply channel 61 parallel to the actuators 50a, 50b and towards the transducers 53 of the actuators 50a, 50b. Above the transducer 53, which is sealed by an O-ring 57 to seal the gap between the recess 55 and the outer surface of the hermetically enclosed actuators 50a, 50b, it is diverted or diverted in the opposite direction (diagonally upward in Figure 1) towards the end side connection 55 of the actuators 50a, 50b, opposite to the acting direction 52a, 52b of the actuators 50a, 50b, and then flows vertically (diagonally downward) through the lateral inlet 62 of the supply channel 61 into the recess 56 of the piezoelectric element 51 of the actuators 50a, 50b, which are arranged at an angle relative to each other, so that the cold cooling medium flows all around the piezoelectric element 51 of the actuators 50a, 50b. The cooling medium propagates evenly from the inside center between the actuators 50a, 50b (slightly diagonally downwards) along the serpentine outer surface of the hermetically contained stacked piezoelectric elements 51 or outward around the piezoelectric elements 51, absorbing the heat generated by the actuators 50a, 50b, and then flows out of the recess 56 via the lateral exhaust ports 64 into two exhaust channels 63a, 63b (on the right and left sides) outside the actuators 50a, 50b.There, in the two lateral discharge channels 63 a, 63 b, the heated cooling medium is directed (upward) to two outlets of the discharge channels 63 a, 63 b of the cooling channel system 60 on the upper part or on the frame of the frame housing unit 2 and is sucked or discharged (upward) in the cooling flow direction 60o. Due to the individual central introduction of the cooling medium and the parallel discharge of the cooling medium on both sides at the two outer sides of the actuators 50 a, 50 b spaced apart from each other in the longitudinal direction 30L, it is possible to minimize the back pressure of the cooling medium in the cooling channel system 60 and therefore maximize the cooling capacity or cooling efficiency of the cooling channel system 60.

[0131] In addition to the end-side connections 55 of the actuators 50a, 50b for controlling the current or power supply, the actuators 50a, 50b are equipped with a temperature sensor 65 for providing temperature data, by means of which, for example, the cooling capacity of the cooling channel system 60 can be adjusted or controlled.

[0132] In summary, the metering system 1 can be separated or disassembled, both structurally as well as functionally, into two units 2, 60, 3, 4, 5, 30, 50a, 50b, which are resiliently supported relative to each other via spring elements 21, as follows: The "static" unit 2 comprises, for example, a frame housing unit 2 and a housing bottom 2' of the frame housing unit 2. In addition, it can comprise at least an integrated cooling device 60, a control board for controlling the metering system 1, an insulation board, a connection board, possible connections, in particular for the supply and outlet of the cooling medium, and a power supply for the metering system 1.

[0133] The "dynamic" unit 3, 4, 5, 30, 50a, 50b or movement mechanism 3, 4, 5, 30, 50a, 50b comprises at least a lever mounting part 3 with a lever mount 4 and a fluid positioning part 5, a lever 30 and two actuators 50a, 50b. Furthermore, it is connectable to the fluid positioning part 5 together with a valve unit 9 and a fluid unit 8 and can optionally comprise a permanent magnet on the lever 30 and a corresponding HALL sensor on the lever mounting unit 3 to determine the position or setting of the lever 30. Either a weighing substance cartridge 17r or a supply line or hose from a tank for the weighing substance can be connected to the fluid unit 8 on a light medium supply connection 17.

[0134] Advantageously, the two units are dimensioned and weighted so that they have approximately the same mass, i.e., so that the total mass of the weighing system 1 is divided into substantially equal parts: the "dynamic" unit and the "static" unit. Thus, as intended by the present invention, even more stable and even higher quality weighing results are achieved, with a particularly high overall metering speed or metering frequency, since the vibrations of the two units damp or balance each other. If, as shown in FIG. 1, the fluid unit 8 is formed with a metering substance cartridge 17r, the content of which changes during metering, this can be taken into account in the overall mass distribution, for example, so that the major masses of the total mass balance each other, at least on average.

[0135] Finally, it is once again pointed out that the device described in detail above is only an exemplary embodiment, which can be modified in various ways by those skilled in the art without departing from the scope of the invention. Thus, for example, the weighing system can be structurally redesigned in such a way that correspondingly shaped and arranged tension springs can be used as spring elements. The use of the indefinite article "ein" or "eine" further does not exclude that the respective feature can also be present multiple times. [Explanation of symbols]

[0136] 1. Weighing System 2 Frame housing unit 2' Bottom of the enclosure 3 Lever mounting unit 4 Lever Mount 5 Fluid positioning section 5s Interface between fluid positioning part and fluid unit 6 rotary joint 7 Adjustment elements / adjustment screws 8 Fluid Unit 9 Valves / Valve Units 10 Valve body 11 Valve chamber / Nozzle chamber 12 nozzles 12' nozzle insert 13 Discharge element / ram 14 Ram Head 15 Tappet spring 16 Ram tip 17 Metering medium supply connection 17r Storage container / measuring substance cartridge 18 Heating Unit 19 Connection / heating cable 20 heating elements 21 spring elements / disc spring sets 30 Lever 30B Ram Movement 30L Lever length 30Q Lever horizontal direction 30T Lever depth direction 31 Lever arm, 2 sides 32 Shorter lever arm side 33 End section 34 holes (for permanent magnets) 35 Longer Lever Arm Side 36 First Actuator Engagement Point 36z First cylinder pin at first actuator engagement point 37 Second Actuator Engagement Point 37z Second cylinder pin at second actuator engagement point 38 Holes / Through Holes / Dimples 39 Wedge-shaped depression 40 Top side of the lever 41 Recess for cylinder pin in lever mount 42 Cylinder pin 42a Outer half of cylinder pin 42b Inner half of cylinder pin 50a, 50b Actuator / Piezoelectric Actuator (herein encapsulated) 51 Piezoelectric elements 52a First Actuator First Direction of Action / Longitudinal Axis 52b Second direction of action / longitudinal axis of second actuator 53 Actuator Transducer 54 Front / tip of actuator 55 Actuator connection 56 Piezoelectric actuator dent 57 O-ring 60 Cooling Device / Cooling Channel System 60i, 60o Cooling flow direction 61 Supply Channel 62 Inlet of supply channel into actuator 63a, 63b Discharge channels, two 64 Outlet of discharge channel from actuator 65 Temperature Sensor AA Cutting line through the weighing system Cutting line through BB lever DR Weighing direction K Actuator engagement point circle P0 center position R Rotation axis / Tilt axis S T First axis of symmetry of the actuator's plane of symmetry S Q Second axis of symmetry of the actuator's plane of symmetry V aFirst connecting line V b Second connecting line X A Engagement axis plane X R Rotation / rotation axis plane

Claims

1. A metering system (1) for metering a metering medium, comprising: The weighing system (1) comprises: A frame housing unit (2), a lever mounting unit (3) having a lever mount (4) supported on the frame housing unit (2); a lever (30) supported by the lever mount (4) for rotation about a tilt axis (R), the lever (30) comprising a two-sided lever arm (31) extending generally in a longitudinal direction (30L) of the lever (30), one lever arm side (35) having a first actuator engagement point (36) close to the tilt axis, the one lever arm side (35) contacting a discharge element (13) at an end portion (33) away from the tilt axis, and the other lever arm side (32) having a second actuator engagement point (37) close to the tilt axis; two actuators (50a, 50b) that, during operation, exert tilting moments in opposite directions on the lever (30) at the first and second actuator engagement points (36, 37); Equipped with The actuators (50a, 50b) are arranged at an angle to each other in a V-shape, and the lever mounting unit (3), the lever (30), and the two actuators (50a, 50b) together form a movement mechanism (3, 4, 5, 30, 50a, 50b), and the movement mechanism (3, 4, 5, 30, 50a, 50b) is supported on a frame housing unit (2) by at least one spring element (21). Weighing system (1).

2. 2. The metering system according to claim 1, wherein the lever (30) is asymmetrical, with the longer lever arm side (35) having the first actuator engagement point (36) close to the tilt axis, the one lever arm side (35) contacting the dispensing element (13) at the end portion (33) away from the tilt axis, and the other shorter lever arm side (32) having the second actuator engagement point (37) close to the tilt axis.

3. 3. The metering system according to claim 1 or 2, wherein the discharge element (13) is a ram (13).

4. 4. The weighing system according to claim 1, wherein the spring element (21) is arranged to support the lever mounting unit (3) against the frame housing unit (2) via the two actuators (50a, 50b) and via the lever (30).

5. A weighing system according to any one of claims 1 to 4, wherein the two actuators (50a, 50b) are located on a common longitudinal side of the lever (30).

6. The weighing system according to any one of claims 1 to 5, wherein the actuators (50a, 50b) are arranged in a V-shape at an angle of up to 150° relative to one another.

7. 7. The weighing system according to claim 6, wherein the actuators (50a, 50b) are arranged in a V-shape at an angle of up to 120° relative to one another.

8. the actuator engagement points (36, 37) on the lever (30) for the actuators (50a, 50b) do not lie in the plane of the tilt axis (R); A weighing system according to any one of claims 1 to 7.

9. 9. A weighing system according to any one of claims 1 to 8, wherein the lever (30) is formed and arranged such that the actuator engagement points (36, 37) are located further away from the longitudinal side of the lever (30) facing the actuators (50a, 50b) than the tilt axis (R) on which the lever (30) is rotatably supported.

10. The center position (P 0 10. The weighing system according to claim 1, wherein the actuators (50a, 50b) engage with the actuator engagement points (36, 37) such that their longitudinal axes (52a, 52b) are in each case substantially perpendicular to the respective connection lines (Va, Vb) between the respective actuator engagement points (36, 37) and the tilt axis (R).

11. 11. The metering system according to claim 1, wherein the actuators (50a, 50b) are arranged tangentially on a circle (K) around the tilt axis (R) on the actuator engagement points (36, 37) so as to perform a substantially linear movement during the operation for metering the metering medium in response to the dispensing and retracting movements.

12. Weighing system according to any one of the preceding claims, wherein the lever (30) has a non-uniform mass distribution.

13. 13. The weighing system according to claim 12, wherein the mass of the lever (30) is distributed along the lever (30) with respect to the tilt axis (R) in such a way that the lever (30) as a whole has the smallest possible (mass) moment of inertia based on the tilt axis (R).

14. Weighing system according to any one of claims 1 to 13, wherein said lever (30) has a number of recesses (38) for reducing its weight.

15. 15. The weighing system according to any one of claims 1 to 14, wherein the total mass of the weighing system (1) is divided approximately evenly between the frame housing unit (2) as a first major mass of the weighing system (1) and the lever mounting unit (3), the lever (30), and the two actuators (50a, 50b) as a second major mass of the weighing system (1).

16. 16. The weighing system according to any one of claims 1 to 15, wherein the lever mounting unit (3) is of multi-part construction and comprises, in addition to the lever mount (4), a fluid positioning part (5) for a hydraulic unit (8) of the metering system (1).

17. 17. The weighing system according to claim 16, wherein the lever mount (4) is rotatably connected to the fluid positioning part (5) via a rotary joint (6) and / or the lever mount (4) and the fluid positioning part (5) are supported relative to each other in a mechanically adjustable manner.

18. 18. The weighing system according to any one of claims 1 to 17, wherein the lever mounting unit (3) comprises a ring structure (4, 5) that annularly surrounds a portion (2') of the frame housing unit (2) by leaving at least one gap.

19. 19. The weighing system according to claim 18, wherein the lever mounting unit (3) is movably supported on the frame housing unit (2) by the spring element (21) arranged in a gap between the lever mounting unit (3) and the portion (2') of the frame housing unit (2).

20. 20. The metering system according to claim 18 or 19, wherein the ring structure (4, 5) comprises a rotary joint (6), and the lever mount (4) of the lever mounting unit (3) is connected in a mechanically adjustable manner to the fluid positioning part (5) via the ram (13) and the lever (30) for adjusting the ram-nozzle distance on the side of the fluid positioning part (5) remote from the rotary joint by means of an adjustment element (7), an adjustment screw (7).

21. the actuators (50a, 50b) are in each case formed in an encapsulated manner, and / or Both actuators (50a, 50b) are in each case equipped with at least one temperature sensor (65), A weighing system according to any one of claims 1 to 20.

22. The metering system according to any one of the preceding claims, wherein a cooling device (60) through which a gas or liquid flows surrounds the actuators (50a, 50b).

23. The cooling device (60) a supply channel (61) located between the actuators (50a, 50b), the supply channel (61) having an inlet (62) into the actuators (50a, 50b); two eccentric discharge channels (63a, 63b) with outlets (64) into the discharge channels (63a, 63b); having 23. The weighing system of claim 22.

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