Weighing sensor structure

Abstract

The present invention relates to a weighing sensor structure having a Roberval mechanism, comprising: a first part having a fixed leg of the Roberval mechanism; a second part having a movable leg of the Roberval mechanism; a third part having an upper lateral link of the Roberval mechanism; a fourth part having a lower lateral link of the Roberval mechanism; a fifth part having a lever arrangement connecting the movable leg to an output side serving for sensing measurement; and a sixth part having a lateral link connecting the movable leg to the lever assembly, wherein at least one of the first to fifth parts comprises an area in the form of at least one type of handle body, at least one hole of which is pierced by at least one part of another of the first to sixth parts integrally connected to said area.

Description

[Technical Field]

[0001] The present invention relates to a structure for a weighing sensor having a Roberval mechanism, in particular for a weighing sensor according to the principle of electromagnetic force compensation, and to a method for its manufacture.

[0002]

[0002] In particular, the present invention relates to a weighing sensor structure having a Roberval mechanism, comprising: a first part having a fixed leg of the Roberval mechanism; a second part having a movable leg of the Roberval mechanism; a third part having an upper lateral link of the Roberval mechanism; a fourth part having a lower lateral link of the Roberval mechanism; a fifth part having a lever arrangement connecting the movable leg to an output side used for sensor measurement; and a sixth part having a coupler connecting the movable leg to the lever arrangement. [Background technology]

[0003]

[0003] Such structures of weighing sensors are well known in the prior art, and the current trend is to make the structures as compact as possible, so that they take up little space in the weighing device in which they are used, and are therefore particularly suitable for applications in which the weighing device has several such weighing sensors. In addition, it is understood that the weighing sensors should also have the highest possible weighing accuracy.

[0004]

[0004] With regard to these requirements, structures in the form of so-called monoblocks have been developed in the state of the art and have become essentially established in this form, as disclosed, for example, in DE 19605087 A1 or EP 2397824 A1. Such structures are manufactured starting from a cubic block of material having a shape and size similar to that of a VHS video cassette, with its long sides corresponding to the longitudinal direction parallel to the transverse links of the Roberval mechanism and its second longest side extending in the direction of the load, so that its two end regions in the longitudinal direction belong, on the one hand, to the fixed leg of the Roberval mechanism and, on the other hand, to the movable leg. By drilling the block transversely and removing material from the monoblock in the form of perforations or cut lines, the monoblock is given the following structure: transverse links are defined at the top and bottom, and the inner area enclosed by these transverse links, which extend to the legs and the top and bottom of the Roberval mechanism, is divided into different functional areas, namely, on the one hand, the area belonging to the fixed legs, and on the other hand, a lever arrangement with usually one, two, or three levers, which are attached to the fixed legs by corresponding bearings and connected to the movable legs or, if applicable, between the levers by so-called couplings. The separation between the levers and the material belonging to the fixed legs is essentially only a thin separation line (the advantages of which are explained, for example, in DE 4119734 A1), because, due to the measurement principle with electromagnetic force compensation, large lever movements beyond the dimension of the separation line do not occur anyway. The last lever in the force transmission path usually has two lateral bores through which a lever extension is attached, on the free end region of which is provided the electromagnetic force compensators and couplings to the position sensors required for this weighing principle, which are well known to those skilled in the art.

[0005]

[0005] Such minimal material removal techniques from transverse perforations, for example by wire EDM, are currently being developed so that even sub-robust mechanisms for coupling the weight load of an internal reference weight can be incorporated into the monoblock, even in the presence of transverse material weakening, as in EP 2397824 A1. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is based on the object of further designing a structure of the above-mentioned type, which has the goal of a satisfactory combination of minimum installation space and the highest possible weighing accuracy. [Means for solving the problem]

[0007]

[0007] This problem is solved by a device-related invention through a further development of a structure of the type mentioned at the beginning, which structure is essentially characterized in that at least one of the first to fifth parts has an area in the form of at least one type of handle body, at least one hole of which is pierced by at least one part of another of the first to sixth parts which is integrally connected to this area.

[0008]

[0008] Through further developments according to the present invention, at least one area of ​​the installation space occupied by the structure, previously reserved for precisely one functional part of the structure, can now be used by at least two different functional parts, or equivalent support structures with different extension directions can be created while saving material. For example, by designing this area within the shape of the handle body, the space formed by the handle body's holes can be used to provide other functional parts with targeted access to areas of the space that are considered desirable for an optimized path for the introduced force flow. For example, the load receiver of the movable leg can be more variably positioned and still be favorably supported by passing a support strut through the fixed leg area formed within the shape of the handle body. Sections of the upper transverse link can also be guided, for example, through the movable leg area, which also allows for greater flexibility in the positioning of the load receiver or more reliable support of the structure and improved power transmission paths. The last lever of the lever arrangement can, for example, be guided through a previously inaccessible area of ​​the fixed leg, thereby simplifying the lever arrangement up to the coupling to the electromagnetic force compensator.

[0009]

[0009] By designing functional areas into two or more handle body configurations, the overall weight can be reduced while maintaining the same rigidity. Therefore, the size of the structure can be smaller, thereby achieving greater compactness and / or lower material requirements for the same weight of the structure. For example, the fixed leg area, in particular, can be formed not as a solidly formed area but as a structure consisting of multiple struts, which can consist of a number of longitudinal struts extending primarily in the longitudinal direction, a number of vertical struts extending primarily in the load direction, and a number of lateral struts extending primarily in the lateral direction. Due to the integral connection between the handle body configuration area and, for example, a section of another functional area passing through it, the integral nature of the connection also ensures that no additional space is required for mechanical connections or adapters to connect two areas that are not integrally connected. In this respect, the present invention further possesses the advantages of the monoblock technology described above.

[0010]

[0010] An example of the shape of one type of handle body is known as a toroidal body (doughnut), whereby due to the shape characteristics of the handle body, the shaping of the boundary of the "hole" (or several holes) is not important, for example a closed frame also represents an example of at least one type of handle body. In a preferred variant, the shape of one or more handle bodies of the functional part is achieved by a frame-like arrangement of three or more struts.

[0011]

[0011] A design consisting of a number of individual struts joined together as a single unit, whether through-hole or not, is also disclosed by the present invention as being advantageous in its own right. The present invention therefore also provides a structure according to the preamble of claim 1, which has at least 12, even 16, in particular 24 longitudinal struts, at least 4, even 2 vertical struts, and at least 4, even 8 lateral struts, as defined above. At least 8, in particular at least 16 of these struts can preferably be provided as diagonal struts, i.e., the extent in one direction is significantly smaller than the extent in the other two directions.

[0012] In one possible embodiment, the functional parts can also be intertwined with one another, so that the penetrating section can be part of an intertwined area with the penetrating section, which also has the form of at least one type of handle body. In this way, a good use of the available installation space is made possible, along with satisfactory rigidity of the respective functional sub-areas. A configuration may be provided in which the holes of such a functional part are penetrated by the penetrating section of the same functional part. In addition, it is also contemplated that there may be embodiments in which components of two different functional parts together form an area in the form of at least one type of handle body, which is penetrated by the penetrating section of one of these functional parts or of yet another different functional part. For example, a section of the movable leg can penetrate the frame structure formed by the upper transverse link and the fixed leg.

[0013]

[0013] In another possible embodiment, the type of handle body of the pierced portion may be two or more, and at least one other hole may be pierced by yet another part of the first to sixth parts that is integrally connected to the other parts and / or the pierced portion. It is also contemplated that each hole of the handle body may be pierced by a part of a different part.

[0014] It may be provided that in addition to one part, at least one further part from the first to fifth parts has a region in the form of at least one type of handle body, at least one hole of which is penetrated by at least one other of the first to sixth parts integrally connected to (and facing) this region of the further part. In this regard, too, multiple penetrations can be provided, and the above-described partial use of joining of local spatial regions can be performed multiple times in different locations.

[0015]

[0015] It is quite possible to envisage variants in which some functional parts have a pierced area and others do not. Preferably, the first part has such a pierced area in the form of at least one type of handle body. Even more preferably, the fifth part has such a pierced area in the form of at least one type of handle body. In a further preferred embodiment, the second part also has such a pierced area in the form of at least one type of handle body. Similarly, it may be provided that preferably, the third part also has a pierced area in the form of at least one type of handle body.

[0016]

[0016] It may further be provided that one or more of the first to fifth sections have regions in the form of handle bodies of a number significantly greater than one type, the holes of which are partially or mostly not penetrated. The first section preferably has regions in the form of handle bodies of at least two types, more preferably at least four types, and in particular at least eight types, but it may also have at least 12, 16, or even at least 24 types. The second section preferably has regions in the form of handle bodies of at least two types, preferably at least four types, and in particular at least eight types. The third and / or fourth section preferably have regions in the form of handle bodies of at least two types, and in particular at least four types.

[0017]

[0017] In a further preferred embodiment, the lever arrangement (fifth part) has a section, in particular a through section, which, viewed in the longitudinal direction of the structure, extends from the movable leg in a direction beyond the bending points associated with the fixed legs and therefore, viewed in the transverse direction, between the laterally outer ends of these bending points. However, in an alternative embodiment, it is also possible that the lever arrangement does not extend longitudinally beyond these bending points, and that the sensor, in particular including the magnet coil arrangement, is located between the bending points of the movable leg and the fixed leg.

[0018] As is common in Roberval mechanisms, bending points (thin bending points) are provided between the fixed legs and the upper transverse links, between the fixed legs and the lower transverse links, between the movable legs and the upper transverse links, and between the movable legs and the lower transverse links. In a preferred design, the bending points do not extend continuously from one end to the other in the transverse direction, but are discontinuous. In a particularly preferred embodiment, one, some, or all of the bending points are divided into at least two, and in particular exactly two, separate transverse sections. In this way, a satisfactory stiffness is achieved, especially in the load direction.

[0019]

[0019] Another preferred embodiment has a structure in which, when projected onto a plane perpendicular to the load direction, a particularly significant section of the lever arrangement, as viewed in the longitudinal direction, is located between the material regions of the first portion, and the ratio of the lateral extent of the lever arrangement section to the lateral extent of the lever arrangement, measured in particular in this first portion, is less than 0.9, preferably less than 0.8, in particular less than 0.7, over at least 40%, preferably at least 60%, in particular at least 80%, or even at least 90% of the longitudinal section of the longitudinal extension of the transverse links. In addition to the thickness of the bending points, the absolute dimensions of the longitudinal extension of the transverse links, which affect the restoring force of the parallelogram arrangement, are determined depending on the normal load of the load cell with which the structure is used.

[0020]

[0020] In a further preferred embodiment, the area of ​​the lever arrangement, as projected in a plane perpendicular to the transverse direction, is in particular traversed several times by sections of the fixing leg, in particular by the pierced area and / or the piercing section. By extending the fixing leg laterally beyond the area of ​​the lever arrangement, an increased rigidity can be achieved, at least in some areas, despite forgoing a solid structure in favor of struts connected together as one piece.

[0021] In a further preferred design, the bearing of the lever arrangement is supported by at least two struts of the first part having different angular positions relative to a plane perpendicular to the load direction. This allows a satisfactory rigidity of the rigid connection of the force-absorbing lever support. Similar supports can be provided for the area of ​​the first part where the mounting coupling of the fixed leg, such as a mounting hole, is located.

[0022]

[0022] A particularly preferred embodiment has a structure in which the force-transducing part of the second part, which takes up the weight load to be absorbed, is arranged in the bending point, seen in the longitudinal direction, between the bending points associated with the mobile leg on the one hand and the fixed leg on the other hand, and is supported in particular by at least two struts of the second part having different angular settings with respect to a plane perpendicular to the load direction, the struts being in particular components of the penetrating section and / or the penetrated area. For example, as will be shown later with reference to the exemplary embodiment in the figures, the struts of the force-transducing support of greater angular adjustment may penetrate the lever of the structure, and the area between the struts of different angular adjustment may be penetrated by the upper transverse link.

[0023]

[0023] This more central positioning of the load receiver allows for a suitable arrangement of structures within the weighing device, for example with respect to its load pan connected to the load receiver, for various application purposes. In particular, it may be provided that the connection between the load receiver and the support frame of the movable leg extends above the upper transverse link. It may also be provided that a support for a reference weight, such as a reference weight inside the weighing sensor, is provided for the movable leg. In particular, it is preferred that the load introduced via the force transducer and the load introduced via the support for the reference weight are introduced into the lever arrangement via the same coupling. A holding unit that holds the reference weight when not in use may be supported on the fixed leg, for example, via a fastening mechanism, in particular coupled to the mounting hole, the fastening mechanism being provided, for example, on the cantilever of the fixed leg.

[0024] The above-mentioned bending points, which may have transverse sections spaced apart from one another, define corner areas in space by their respective outer ends, which corner areas have a convex shell enclosing the spatial area of ​​the defined volume. The convex enclosure is formed by connecting the outer ends of each upper and lower bending point to one another and to the right side. In a particularly preferred embodiment, it is provided that the product of this volume and the density of the material of the structure is at least 1.2 times, preferably at least 1.4 times, and in particular at least 1.75 times, greater than the mass of the material of the structure located in this volume. This factor can be 2 or more, in particular 2.5 or more, even 3 or more, or even 4 or more.

[0025]

[0025] This aspect is also independently advantageous and is presented by the present invention as being independent of any penetration of the functional part. The present invention therefore also provides a structure having the general features of claim 1, in which the convex shell at the laterally outer end of the bending point contains a volume, the product of which volume and the density of the material of the structure is at least 1.2 times, preferably at least 1.4 times, and in particular at least 1.75 times, greater than the mass of the material of the structure located within this volume. This factor can also be 2 or more, in particular 2.5 or more. Due to the associated material distribution, higher surface moments of inertia, and therefore higher bending moments, are achieved in relation to the total material used for each load direction, and therefore a satisfactory level of stiffness of the functional components of the structural device is achieved in a material-saving manner.

[0026] In a preferred embodiment, the maximum extension of the lateral movable leg is at least 1.125 times, preferably at least 1.25 times, and in particular at least 1.5 times, smaller than that of the fixed leg. Alternatively or additionally, the lateral extension of the lateral link tapers toward the movable leg with an inclination of at least 6%, preferably at least 12%, and in particular at least 18%. This variant is particularly suitable for applications with lower loads. However, in particular for higher loads, the maximum extension of the lateral movable leg may be at most 1.33 times, preferably at most 1.25 times, and in particular at most 1.125 times, smaller than that of the fixed leg, but may also be greater than the fixed leg, preferably by at most the latter factor. In this variant, the diagonal extension of the lateral link is relatively more important than the mass of the movable leg. Alternatively or additionally, the lateral extension of the lateral link may taper in the direction towards the movable leg with an inclination of 6% or more, preferably 12% or more, in particular 18% or more, or may taper and / or widen with an inclination of at most 18%, preferably 12%, in particular 6% or more. In this context, the invention also provides a set of two or more, preferably three or more, structures according to claim 1, having different lateral extensions of the movable legs.

[0027] In a possible embodiment, measures can be taken, particularly with regard to installation space, to make the distance from the lower transverse link to the upper transverse link in the load direction smaller than the lateral extent of the bending point between the upper transverse link and the fixed leg, in particular by more than 1.2 times, preferably more than 1.4 times, in particular more than 1.6 times. However, variants are also contemplated in which this distance is equal to the lateral extent of the bending point between the upper transverse link and the fixed and / or movable leg, or is greater than this, in particular by more than 1.1 times, also more than 1.2 times, or even more than 1.3 times.

[0028]

[0028] In a particularly preferred embodiment, some, and in particular all, of the first to sixth parts are connected to each other as a single unit, the components themselves as well as the connections therebetween being preferably manufactured using an additive process.

[0029]

[0029] As also illustrated in the exemplary embodiment, the coil holder attached to the lever of the structure is preferably integrally formed as a single piece by an additive method, and thus is preferably not a separate component mechanically connected to the lever.

[0030]

[0030] The present invention therefore also relates to the manufacture of a structure according to any of the aforementioned aspects using an additive process, such as a 3D printing process. The specific forming technique is not limited to specific techniques known per se in this regard, for example, strand deposition processes, powder bed processes, selective laser melting (SLM), electron beam melting, ADAM processes, LCM processes, modified powder bed processes (hypoids with intermediate milling) can also be used. It is also contemplated to use different materials by applying different powders in a powder bed process at predetermined points, for example at bending points.

[0031]

[0031] With regard to the material, plastic materials can be used in the same way as metallic materials. For example, materials based on aluminum compounds such as AISi10Mg can be used. In a particularly preferred embodiment, it is provided that the iron content of the material is at most 0.1% by weight, preferably at most 0.08% by weight, more preferably at most 0.06% by weight, in particular at most 0.05% by weight. This ensures that the interference effects of the electromagnetic force compensation part are small, especially when the coil holder itself is part of an additively manufactured system.

[0032]

[0032] This manufacturing method is also considered by the present invention to be advantageous for designs according to the general concept of claim 1 in which individual functional parts are not penetrated by other functional parts in the sense that they penetrate holes in areas from the shape of the handle body, and therefore independently and autonomously discloses the manufacture of structures according to the general concept of claim 1 by additive processes (3D printing), as well as the structure of the weighing sensor thus manufactured.

[0033] In a particularly preferred process design, the bending points of the Roberval mechanism are reworked in a material-removal machining step following the additive process, thereby bringing them to their final shape. Additionally or alternatively, temporary support struts can be created in the additive process, which are subsequently removed again by removing material and are therefore not part of the finished structure. Material removal can occur after the finishing step, particularly at the bending points. In a particularly preferred embodiment, the coupling between the movable leg and the lever arrangement (or the lever, in the case of a single lever for a lever coupling) is reworked, and / or the bearing for the lever, particularly in the area near this coupling, is reworked in a material-removal machining step. However, designs in which the finishing of the thin bending points between the transverse link and the leg is carried out beforehand in the additive process are also conceivable. Regarding these bending points as well as the coupling and lever bearing, it is preferably provided that they are formed only by thin-walled areas of material, i.e., by material bridges of smaller thickness, as specifically shown in the exemplary embodiments described below. Preferably, complex designs, especially cross spring joint designs, are not used.

[0034]

[0034] When designing the layout, individual fixing points such as supports for the lever, bending points, and fastening points of the fixed legs can be defined in one step, and the force flow paths between the individual fixing points can be determined in a further step, and these variations can be compared with each other, and if the intersection of two force flow paths or the support structures of the individual functional components results in the desired force flow path arrangement, a design is selected from the shape of the handle body for an area having holes in the intersection area penetrated by another of the first to sixth parts in order to create an installation space area that is only accessible to one functional part in relation to the occupation of the installation space by the other functional part. In this way, a bionic structure with good force conduction within the structure can be achieved while keeping the installation space relatively small. In a further preferred embodiment, the structure has at least one receptacle that extends primarily, preferably entirely, laterally for temporarily connecting at least two of the first, second, and fifth parts (the fixed leg, the movable leg, and the lever assembly) via a fixing element that can be temporarily inserted into the receptacle. For this purpose, the components that form the receptacle have surface areas that are aligned with each other when viewed laterally, within which the boundary of the receptacle is defined. Two or more such receptacles may also be provided. In a preferred embodiment, a receptacle for receiving the fixing element is provided, and this receptacle extends across the fixed part, the movable part, and the lever. The receptacle may be designed as a through-hole through the surface area or as a notch that is not completely enclosed so that movement of the parts relative to each other is limited. By temporarily inserting the fixing element into the receptacle(s), undesirable loads on the parts and / or undesirable large movements of the parts relative to each other may be avoided, for example, when post-processing is performed after the additive manufacturing process.

[0035]

[0035] In this sense, and independently of the exact design of the individual components, a method for manufacturing a weighing sensor structure having the generic features of claim 1 is disclosed as independently worthy of protection, in which its first to sixth parts are formed as one piece in an additive process, in which at least one receptacle, extending primarily, preferably essentially laterally, is created for at least two temporary, limited-motion connections of the first, second and fifth parts of the structure, which temporary, limited-motion connections can be brought about by fixing elements introduced into the receptacles, said method preferably comprising downstream working steps in the additive manufacturing process, namely the steps of introducing the fixing elements into the receptacles and removing the fixing elements again from the receptacles, and at least the steps of material-removing machining of the coupling and / or removal of the partial connecting material bridges produced in the additive process, which steps are preferably carried out during the temporary fixation brought about by the introduction of the fixing elements. It is understood that other downstream processing steps (such as mounting parts such as coils for assembling the weighing sensor, position sensor, PCB / S, load introduction interface, power supply, and / or wiring) are also preferably performed when temporary fusion is enabled. The safety element can be, for example, a safety bolt. If the alignment is not perfect, the holder may have to be machined, for example by drilling / milling, to introduce the safety element.

[0036]

[0036] Erosion processes can be used to release the structure after the additive manufacturing process. In this context, it is also provided that the end regions of the fixation legs, which are preferably axial in the longitudinal direction, form flat surfaces extending in the lateral and loading directions, which can be used as assembly surfaces and / or formed by such erosion.

[0037]

[0037] Furthermore, the present invention also relates to a weighing sensor, preferably based on the principle of electromagnetic force compensation, having a structure formed according to one of the aforementioned aspects. In particular, the attachment, which can be attached to the intended attachment point of the structure, includes a calibration weight, a calibration stroke, a magnet system, a coil, a sensing device, and an electronic circuit. The present invention also includes a weighing device having one or more such weighing sensors. The principle of electromagnetic force compensation is well known to those skilled in the art and therefore will not be further described here; in this regard, reference is made, for example, to EP 1 726 926 B1, in particular paragraph

[0008] . Such weighing sensors are preferably designed to weigh weights in the low load range, preferably at most 1000 g, preferably at most 800 g, more preferably at most 600 g, and in particular at most 500 g. Furthermore, as already mentioned, it is preferred that the lever arrangement has only one lever. As will be shown in the embodiments below, an arrangement for applying a reference weight is also preferably provided, this arrangement being connected to the movable leg and being integrally formed therewith by an additive process.

[0038] Further features, details and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 is a perspective view of a structure for a weighing sensor. [Figure 2] FIG. 10 is another perspective view from a different angle. [Figure 3] FIG. [Figure 4] FIG. 1 is a plan view of the structure in the load direction. [Figure 5] FIG. 1 is a plan view from the rear (longitudinal) of the structure. [Figure 6] FIG. 2 shows the section of FIG. 1 with attachment to a weighing sensor. [Figure 7] FIG. 10 is a partial cross-sectional view of a portion of another structure near the movable leg. [Figure 8]FIG. 10 is a perspective view of the end portion up to the movable leg of the other structure. [Figure 9] FIG. 10 is a view of another structure shown in a slightly more perspective than simple side view. DETAILED DESCRIPTION OF THE INVENTION

[0040]

[0039] In the perspective view of Figure 1, structure 100 is shown, with the load direction g in this view being from top to bottom, the longitudinal direction being substantially a diagonal from the top left to the bottom right, and the lateral direction being the other diagonal.

[0041]

[0040] The upper transverse link 30 of the Roberval mechanism of the structure 100 is not solid but is composed of several interconnected struts. In addition, the bending point between the upper transverse link 30 and the fixed arm 10 is laterally divided into two separate transverse sections 130R, 130L, as is the bending point between the upper transverse link 30 and the movable arm 20. One longitudinal strut 31 of the upper transverse link 30 connects the transverse sections 130R, 230R or 130L, 230L of the bending points between the upper transverse link 30 and the fixed arm 10 and the movable arm 20, which are assigned to each other in the transverse direction Q. A diagonal strut 32 connects the diagonally opposite transverse sections 130R, 230L and 130L, 230R, respectively. At the level of the intersection of the diagonal struts, the transverse strut 33 is still arranged between the diagonal strut 32 and the longitudinal strut 31 .

[0042]

[0041] Due to the inclination with respect to the longitudinal direction L, the upper lateral link 30 tapers from the side of the fixed leg 10 towards the movable leg 20. In the embodiment shown, the lateral extension of the bending point 230 is about 2.75 times smaller than the lateral extension of the bending point 130. This taper is also clearly visible in Figure 5, where the normal plane is the longitudinal line of sight from the movable leg 20 to the fixed leg 10. The inclination of the longitudinal strut 31 with respect to the longitudinal direction is about 18.5° in this example embodiment.

[0043]

[0042] The lower lateral link 40 has the same structure as the upper lateral link 30 and includes longitudinal struts 41, diagonal struts 42 and cross struts 43, connecting the bend point cross sections 140L, 140R toward the fixed arm 10 and 240L, 240R toward the movable arm 20.

[0044] The movable leg 20 has a support frame lying essentially in a plane subtended in the load direction g and the lateral direction Q. In this support frame there is an upper lateral strut 23, at the lateral end of which a vertical strut 24 extends in the load direction, and two diagonal struts 22 form a support cross section (see FIG. 5). To accommodate the load to be measured, a load sensor 28 is provided with a bore 29, shown in this example as a circular disk, connected to the transverse brace 23 by a linkage 27. In this embodiment, the linkage 27 has two longitudinal struts 271 fixed to the transverse bar, which are connected to each other by two diagonal struts 272 forming a support cross section. In this embodiment, the load receiver 28 and the linkage 27 are located above the upper lateral link 30. In addition, the load receiver 28 is supported by two or more solid support struts 26, which are fixed to the lower region of the vertical support 24. The extension direction of the support struts 26 includes components in the load direction g, the longitudinal direction L, and the lateral direction Q, and therefore these are referred to as spatial diagonal supports 26. As can be seen from FIG. 3, the spatial diagonal supports 26 extend orthogonally in the lateral direction (in FIG. 3, the lateral direction is normal to the page) at an angle of approximately 23° to the longitudinal direction L in the example shown. Two spatial diagonal supports 26 are also connected by a diagonal strut 262 (see FIG. 5) that forms a support cross section. The load receiver 28 is rigidly connected to the carrier frames 23, 24, and 22 via the spatial diagonal supports 26 and the linkage 27. The diagonal strut 32 of the upper link 30 passes through an opening defined by the spatial diagonal supports 26, the load receiver 28, the longitudinal strut 271, the lateral strut 23, and the vertical strut.

[0045] In this embodiment, the location of the lateral section of the bending point for the upper lateral link 30 is located at approximately the height of the intersection of the vertical support 24 and the lateral support 23 of the moving leg 20, and the location of the lateral section of the bending point for the lower link 40 is located through the bending extension of the vertical support 24, the ends of which are connected by a further (lower) bar 25. In the illustration, the bending points 130, 140, 230, 240 do not appear as thin-walled points, but their shaping is still carried out in a material reduction processing step, starting from the structural body shown.

[0046]

[0045] Starting laterally from the center of the cross strut 25, the connection extends to the coupling 60, which connects the movable leg 20 to the lever 50 of the lever arrangement, which in this embodiment consists of only one lever. The extension of the coupling 60 in the longitudinal direction can be clearly seen in Figure 3, in which, in the direction Q, the coupling 60 is again greatly reduced in width, see Figure 5.

[0047]

[0046] The lever 50 is designed as a two-arm lever, with a short arm 51 facing the movable leg 20, to which a coupling 60 is connected from below, and a long lever arm 54, at its remote end, is provided with a coupling 56 for an electromagnetic force compensation part of the weighing sensor (Fig. 6). The free end 58 is used, as is common in the state of the art, to determine the position for a position sensor (Fig. 6). However, the invention is not limited to lever configurations with only one lever. Multi-lever systems, in particular with two or three levers, can also be formed. The use of installation space according to the invention is also advantageous in this respect.

[0048] 1 and 5, the lever is supported on the fixed leg 10, which is divided, when viewed laterally, at a left bearing point 150L and a right bearing point 150R (the L and R for "left" and "right" refer to the view of FIG. 1 and are therefore not consistent with the view of FIG. 5 in terms of the left and right directions therein). As can be seen particularly well in FIG. 3, the bearing points 150R, 150L are located very close to the support frames 23, 24, 22, 25, and, measured from the bending points 130, 140 towards the fixed leg 20, the bearing 150 is approximately at a distance of more than 90% of the extension of the lateral links 30, 40 in the longitudinal direction L.

[0049]

[0048] The short lever arm 51 of the lever 50 has a lateral reinforcement 152 extending between the support portions 150L and 150R and is substantially formed from the lateral reinforcement, which in this embodiment is formed substantially triangular in projection perpendicular to the load direction g, and the coupler 60 is connected to the free end, i.e. approximately at the apex of a triangle having an obtuse angle.

[0050] The long lever arm 54 spans most of the longitudinal extent of two longitudinal struts 55 which converge near the coupling 56, diverge towards separate lateral bearing points 150L, ​​150R and diverge again near these bearing points. The free end of the long arm 54, which is integral with the entire lever 50, extends longitudinally across the bending points 130, 140 and passes through the vertical support 11 of the fixed leg 10.

[0051]

[0050] The fixed leg 10 has a vertical frame 11 that extends essentially in a plane perpendicular to the longitudinal direction and a horizontal frame 12 that extends towards the movable leg 20 essentially in a plane perpendicular to the load direction (Figure 3).

[0052] The vertical frame has two transverse struts 113 and two vertical struts 114, with bending points 130, 140 located near their respective connections. The opening defined by the upper cross brace 113 and the diagonal brace 32 of the upper link 30 is penetrated by the diagonal support 26 of the movable leg 30. The horizontal frame 12, as best seen in combination with FIGS. 3 and 4, has two essentially parallel longitudinal struts 121, near their distal end regions of which a transverse strut 123 is provided. In this embodiment, each of these struts 121, 121, and 123 is provided with a mounting hole 129 through which the structure can be fastened to a weighing device. Approximately at the height of the mounting hole 129, a transverse brace 128 connecting the longitudinal struts 121 is attached.

[0053] Mounting holes 125 are provided on the arms 124 of the horizontal frame, via which an arrangement for applying a reference weight can be attached. The reference weight (not shown) can be placed on the support 21, which is rigidly connected to the vertical support 24 of the movable leg 20 via a linkage 214. In this embodiment, both the load of the weight to be measured, which is applied to the load receiver 28, and the load of the reference weight, which is applied to the support 21, are transmitted via the same coupling 60 between the movable leg 20 and the lever 50.

[0054]

[0053] Viewed in the transverse direction Q, the longitudinal struts 121 of the horizontal frame are flanked on either side by lower longitudinal struts 14 and upper longitudinal struts 13 which, viewed in relation to a plane perpendicular to the transverse direction, are connected to the respective longitudinal struts via diagonal struts 15. The transverse struts 13 are connected to each other and to the transverse struts 113 of the vertical frame via further struts forming a support triangle 16. In addition, a diagonally extending strut 17 connects the transverse strut 113 to the horizontal frame 12 via a support cross section 128. The diagonal support 17 passes through an opening defined by the longitudinal struts 55 and the transverse reinforcement 152 of the lever 50, so that the lever 50 and the fixed leg 10 pass through each other. The assembly area with the assembly holes 129 of the cross struts 123 is also connected to the support cross sections 128 and the longitudinal struts 121 via longitudinally and laterally extending support cross sections. It can be seen that the assembly area is supported multiple times by the struts, such as at bearing points 150R, 150L.

[0055]

[0054] Thus, the longitudinal struts 13, 121 and 14 are, as can be seen particularly well in FIG. 4, outside the lever 50, as viewed laterally, with respect to the centrally arranged lever 50.

[0056]

[0055] On the side of the vertical frame 11 facing away from the movable leg 20, a mounting bore 198 for the magnet-coil arrangement of the electromagnetic force compensator 70, which comprises a magnet and a coil, is provided via the linkage 19, the coil being attached to the coil holder 56, and a mounting hole 199 is also provided for the position sensor 80 which interacts with the free end 58 of the lever 50. This assembled state is shown pictorially in the section of Figure 6. It will be understood that the corresponding mounting coupling in the case of the magnet-coil arrangement arranged on the other side of the vertical frame 11 is now arranged on the side facing the movable leg 20.

[0057] All of the components 10, 20, 30, 40, 50, and 60 shown in Figures 1-5 are created together as a single unit in this example embodiment by an additive manufacturing process. As previously mentioned, one design may specify that the final shape of the thin bend at the bend point between the lever and leg of the Roberval mechanism be manufactured by a material removal process starting from an additively formed material region. Alternatively, another design may provide for all additive manufacturing. Materials for the structure 100 may include plastic and metal materials. While all parts can be made from the same material, the use of different materials is also contemplated, such as forming the bend point from a different material than the other regions.

[0058] Another exemplary embodiment will now be described with reference to Figures 7 to 9. A structure 100', shown in a slightly perspective view in Figure 9, is also fabricated by an additive process, in this embodiment from a 3D printable powder, in this example using AISi10Mg with an iron content of less than 0.05% by weight.

[0059]

[0058] The structure 100' is also constructed according to the principles of the Roberval mechanism and has a fixed leg 10', a movable leg 20', an upper lateral link 30' and a lower lateral link 40' (the same reference numbers, with primed references, are used for the same components in the second embodiment).

[0060]

[0059] It can be easily seen from Figure 8 that the extension of the movable leg 20' in the lateral direction Q is again less than that of the fixed leg 10'. The locations of the thin bending points 130R', 130L', 230R' and 230L' again form a trapezoid.

[0061] As in the first embodiment, the load receiver 28' is connected to the axial end region of the movable leg 20' not only via a linkage 27' substantially parallel to the upper transverse link 30', but also via a diagonal strut extending obliquely in a plane perpendicular to the transverse direction Q, which is connected to a region of the movable leg located further downward when viewed in the load direction and thus penetrates the region of the lever 50'. When viewed in a projection perpendicular to the transverse direction, the region of the movable leg 20' between the connections towards the load receiver 28' is penetrated by a region of the upper transverse link 30' (FIG. 8). In this exemplary embodiment, the upper transverse link 30' has two struts 32', 33' on the left and right sides, which extend essentially in a longitudinal direction with a diagonal component, and the struts 32' from the left and right sides in the penetration region of the movable leg 20' are connected to each other.

[0062] In contrast to the first exemplary embodiment shown, the coil-side end of the lever 50' does not protrude beyond the frame structure 114' of the fixed leg 10'. In this way, the frame structure 114' can be formed as a flat contact surface at the axial end when viewed in the longitudinal direction. At the location of the surface F, the structure can be removed from the device after its manufacture, for example by erosion. Nevertheless, as in the first embodiment, the coil holder 56' and the free lever end 58' provided for sensor coupling are integral parts of the additively manufactured structure 100' and are not additional components that are only joined to it after the structure 100' has been manufactured.

[0063] As in the first embodiment, the connections between the lateral links 30' and 40' and the fixed leg 10' and the movable leg 20' are formed by thin areas in the sense of thin-walled material bridges (see 130R', 140R' in FIG. 9). These can be present in their final configuration by mechanical reworking or can be pre-created using additive processes.

[0064] On the other hand, for the coupler 60' and bearing points 150L', 150R', best seen from FIG. 7, it is contemplated that their final shape is produced by a mechanical finishing operation, for example milling, in which several milling cutter machining steps are placed one after the other, the overlapping contours of which form the contours of the coupler / bearing points.

[0065] For any subsequent processing after the manufacture of the structure 100' in the additive process, the movable parts are preferably temporarily fixed to one another. This can be done by forming locking pin receptacles Q1, Q2, and Q3 shown in FIG. 9 in the material areas of the parts to be fixed to one another to accommodate screw pins (not shown) while still in the additive process. For this purpose, the fixed leg 10', the movable leg 20', and / or the lever 50', when viewed in a transversely orthogonal projection, have overlapping surface areas through which the locking pin receptacles Q1, Q2, Q3 pass. Here, Q1 passes through the areas of the fixed leg 10' and the movable leg 20' near the bearing point 150' (crossing the coupler in the central area). A safety pin guided by Q1 can protect the coupler when machining the bearing points (top and bottom) and separating the material webs. Q2 extends both in the region of the fixed leg 10' and in the region of the lever 50' as well as through the diagonal connection between the movable leg 20' and the load receiver 28' already described above.

[0066]

[0065] This configuration is also designed for a low load range, preferably for loads below 1000 g, in particular below 500 g. Although an arrangement with several levers is in principle possible, one with only one lever 50' is also preferred in this embodiment. As in the first embodiment, it is preferably provided that the material web (see, for example, 154' in Figure 8), in particular connecting the lever 50' to other components such as the fixing leg 10' or the upper transverse link 30', is still formed during the additive manufacturing process and is then removed once the fixation has been created, for example via the fixing pin receptacles Q1, Q2, Q3.

[0067]

[0066] In this way, necessary post-processing steps, such as cutting threads for fastening holes or milling away production-related support structures that the final structure must not have, or additional safety guards in the form of material webs, such as the aforementioned lever safety devices, are fastened without damaging the delicate lifting structures and their couplings. The installation of other components, such as coils or wiring, can also be carried out before the fuse pins inserted in the locking pin receptacles Q1, Q2, Q3 are removed, i.e. before the temporary fixation is removed.

[0068]

[0067] Thus, in the finishing process after 3D printing the structure, the following steps may be performed: (1) attaching locking pins, (2) post-processing bearing points and / or couplers, e.g., by machining, and removing material webs, (3) further assembling the load cell modules to the base structure by adding one or more of coils, position sensors, PCB / S, load application interfaces, power supplies, wiring, etc., and (4) removing locking pins before operation.

[0069]

[0068] Due to the design with numerous longitudinal, lateral and vertical struts as well as diagonal struts, the structure 100 is constructed with a relatively low mass in relation to the overall extent of the structure, but nevertheless has high rigidity and allows for increased possibilities to use local installation space areas by penetration of different functional components, thereby allowing for more variable positioning of the components of the individual functional parts and enabling configurations that are suitable for controlling the flow of power paths.

[0070]

[0069] The present invention is not limited to the embodiments shown in the illustrated examples, but rather the features of the foregoing description and the following claims may, both individually and in any combination, be essential to the realization of the invention in its various embodiments. [Explanation of symbols]

[0071]

[0070] 10 Fixed legs 11 Vertical Frame 12 horizontal frames 13 Longitudinal Support 14 Longitudinal Support 15 Diagonal Support 16 Support triangle 17 Diagonal Support 19 Link mechanism 20 Movable legs 21 Support reference weight 22 Diagonal Support 23 Horizontal support 24 vertical support 25 Horizontal support 26 Spatial Diagonal Support 27 Link mechanism 28 Load receiver 29 holes 30 Upper lateral link 31 Longitudinal support 32 Diagonal Support 33 Horizontal support 40 Lower lateral strut 41 Longitudinal support 42 Diagonal Support 43 Horizontal support 50 Lever 51 Short lever arm 54 Long lever arm 56 Coil holder 58 Free lever end 60 Coupling 70 Electromagnetic force compensation section 80 Position Sensor 100 Structure for weighing sensor 113 Horizontal Support 114 Vertical support 121 Longitudinal Support 123 Horizontal Support 124 Outrigger 125 Assembly hole 128 Support Cross Section 129 Assembly hole 130L, 130R bending point 140L, 140R bending point 150L, ​​150R bearing position 152 Lateral reinforcement 198 Assembly hole 199 Assembly hole 214 Link Mechanism 230L, 230R bending point 240L, 240R bending point 262 Diagonal Support 271 Longitudinal Support 272 Diagonal Support g Load direction L Longitudinal direction Q Horizontal Q1, Q2, Q3 Locking Pin Receptacles F surface

Claims

1. A weighing sensor structure (100) having a Roberval mechanism (10, 20, 30, 40), a first part having a fixed leg (10) of the Roberval mechanism; a second part having a movable leg (20) of the Roberval mechanism; a third part having an upper lateral link (30) of the Roberval mechanism; a fourth part comprising the lower lateral link (40) of said Roberval mechanism; a fifth part comprising a lever arrangement (50) connecting said movable leg (20) to an output side serving as a sensing measurement; a sixth part having a coupler (60) connecting the movable leg (20) to the lever arrangement (50); A structure comprising: At least one of the first to fifth parts has a region in the form of at least one type of handle body, and at least one hole of the region is penetrated by at least one part integral with the region of another of the first to sixth parts different from the part having the region, a force-transducing part (28) of the second part, which receives a weight load, is arranged in the longitudinal direction (L) between the bending points (230, 240; 130, 140) assigned to the movable leg (20) on the one side and the fixed leg (10) on the other side, the force transformer (28) is supported by at least two struts (27, 26) of the second part having different angular settings relative to a plane perpendicular to the load direction (g), the struts (26) being components of the penetrating part; structure.

2. 2. The structure of claim 1, wherein the type of the handle body of the pierced portion is two or more, and at least one other hole is pierced by another portion and / or a further portion of the first to sixth portions that is at least partially integrally connected to the pierced portion.

3. 3. The structure of claim 1, wherein in addition to said one portion, at least one further portion from said first to said fifth portions has a region in the form of at least one type of handle body, at least one hole of which is pierced by at least one other of said first to said sixth portions integrally connected to said region of said further portion.

4. 4. The structure of claim 1, wherein the lever arrangement (50) has a portion (54) that, when viewed in the longitudinal direction (L) of the structure (100), extends outward from the movable leg (20) beyond an inflection point (130; 140) associated with the fixed leg, and that, when viewed in the lateral direction (Q), extends between lateral outer ends (130L, 130R; 140L, 140R) of the inflection point.

5. A structure described in any one of claims 1 to 4, wherein when projected onto a plane perpendicular to the lateral direction (Q), the lever configuration area (54) is crossed by a portion of the fixed leg.

6. 6. A structure according to any one of claims 1 to 5, wherein when viewed in a plane perpendicular to the load direction (g), a section of the lever arrangement is located between material regions of the first part when viewed in the longitudinal direction (L).

7. A structure described in any one of claims 1 to 6, wherein the load introduced through the force conversion part (28) and the load introduced through the support part for the reference weight are introduced to the lever configuration (50) through the same coupler (60), and / or a support part for a holding unit that holds the reference weight when not in use is provided on the fixed leg part (10).

8. 8. A structure according to any one of claims 1 to 7, wherein the bending points (130, 140; 230, 240) of the upper (30) and / or lower (40) lateral links on the side of the fixed leg and / or the movable leg have, viewed in the lateral direction (Q) from one another, spaced apart lateral sections (130L-130R; 140L-140R; 230L-230R; 240L-240R).

9. 9. The structure according to any one of claims 1 to 8, wherein the convex enclosure formed by connecting the portions (130L,R; 140L,R; 230L,R; 240L,R) of the inflection points or the convex enclosure formed by connecting the laterally outer ends of the inflection points defines a volume (v), and the product of the volume and the density (ρ) of the material of the structure (100) is at least 1.2 times greater than the mass (m) of the material of the structure (100) located within the volume.

10. A structure as described in any one of claims 1 to 9, wherein the maximum extension of the movable leg in the lateral direction is at least 1.125 times smaller than that of the fixed leg.

11. A structure described in any one of claims 1 to 10, wherein multiple parts from the first part to the sixth part are integrally joined to each other.

12. A manufacturing method for producing a structure according to any one of claims 1 to 11 using an additive manufacturing method.

13. 13. The manufacturing method of claim 12, wherein following the additive manufacturing method, bending points of the Roberval features are reworked in a material reduction machining step and / or temporary connecting struts for manufacturing the structure are created in the additive manufacturing method, which connecting struts are subsequently removed by reducing material.

14. A weighing sensor comprising a structure according to any one of claims 1 to 11.

15. A weighing device comprising one or more weighing sensors according to claim 14.

Images