Monoblock sensor body and its manufacturing method

Abstract

To provide an improved monoblock sensor body for a load cell with high accuracy and high performance.SOLUTION: A monoblock sensor body (100) of a load cell based on an electromagnetic force compensation mechanism, the monoblock sensor body comprises a Roberval mechanism, a lever constituent body (60), and mounting portions (11, 12, 21, 22). In the monoblock sensor body (100), at least one of the mounting portions includes cavities (15, 16; 25, 26) that reduce an available solid angle for straight propagation paths extending from an internal thread to one or more of the closest flexure point portion, a coupling portion, and in particular the closest fulcrum. Meanwhile, material boundaries (17; 27) of the monoblock sensor body (100) close the cavities (15, 16; 25, 26) over at least a bridging width with respect to height direction side ends (101; 102) of the monoblock sensor body corresponding to the closest flexure point portions (31, 32; 41, 42) in the monoblock sensor body (100).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001]

[0001] The present invention is in the field of load detection. In particular, the present invention relates to a type of load detection in which a Roberval mechanism is involved to receive a load at its movable column, a lever arrangement is provided coupled to the movable column of the Roberval mechanism, the load measurement principle is electromagnetic force compensation, and a corresponding mechanism is connected to the lever arrangement. More particularly, the present invention relates to a type of load cell in which the Roberval mechanism and the lever mechanism are defined in one single material block, i.e. in a monoblock sensor body.

[0002] More specifically, the present invention relates to a monoblock sensor body of a load cell based on an electromagnetic force compensation mechanism, which comprises a Roberval mechanism, a lever arrangement having one or more levers connected on one side by a connection to the movable column of the Roberval mechanism and on the other side connectable to the electromagnetic force compensation mechanism, each having a fulcrum, and a mounting part for directly or indirectly mounting the fixed column of the Roberval mechanism via an intermediate component to a housing side of a weighing module and / or for mounting a load receiving member directly or via an intermediate component to the movable column, at least one mounting hole of which is preferably at least oriented in the load direction. and at least one mounting hole extending along the length of the parallel upper and lower beams of the Roberval mechanism, which are connected to the fixed and movable columns via the first and second flexure points, respectively, and which has a mating female thread so that the male thread of the fixing screw, which is screwed into the mounting hole in a state where it is mounted in the mounting hole up to the axial thread end, can be screwed into the mounting hole, and which has one of the first upper flexure point, the second upper flexure point, the first lower flexure point, and the second lower flexure point as the relatively nearest flexure point. Furthermore, the present invention also relates to a load cell having such a monoblock sensor body, a weighing device as an electronic balance having one or more of such load cells, and a method for manufacturing such a monoblock sensor body. [Background technology]

[0003]

[0003] Such monoblock sensor bodies are well known in the art. For example, EP 2 397 824 B1 (see, for example, FIG. 8 of this document) shows such a typical monoblock sensor body, an electromagnetic force compensation mechanism with a force coil, an electromagnetic force generator and a displacement sensor, and a support member for connecting to the lever arrangement of the monoblock sensor mechanism body. It is proposed to integrate a sub-roberval mechanism in the monoblock sensor body for coupling to an internal (calibration) weight. The monoblock sensor body is fixed to an electronic balance case (not shown) through a mounting member 7 by a screw extending laterally (widthwise) of the monoblock, which attaches the mounting member 7 to a fixed column of the monoblock sensor body.

[0004] DE 196 05 087 A1 also discloses such a monoblock sensor body, in which mounting holes are provided in the corner regions of the monoblock and extend in the longitudinal direction of the monoblock.

[0005]

[0005] EP 1 643 223 A1 also discloses a monoblock sensor body, in which a coupling element for coupling a lever mechanism to a movable column is provided with a thinned portion in the length direction and a thinned portion in the width (lateral) direction.

[0006]

[0006] Especially for load cells with high resolution, these monoblock sensor bodies are particularly suitable for high accuracy and performance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] EP2397824B1 [Patent Document 2] DE19605087A1 [Patent Document 3] EP1643223A1 Summary of the Invention [Problem to be solved by the invention]

[0008] The aim of the present invention is to further improve such monoblock sensor bodies in terms of good accuracy and performance. [Means for solving the problem]

[0009]

[0007] To address this objective, the present invention provides a monoblock sensor body as originally introduced, essentially characterized in that at least one mounting portion has a cavity which reduces the available solid angle of a straight-line propagation path extending from the female thread to one or more of the nearest flexure point, the joint, and especially the nearest fulcrum, while the material boundary of the body closes the cavity over at least the bridge width to the heightwise side end of the body corresponding to the nearest flexure point.

[0010]

[0008] The provided sensor body protects the sensitive sensor body parts against stresses which arrive in particular via a linear propagation path, resulting for example from mechanical stresses occurring when tightening mounting screws and which cause deformations of the initial position of the sensitive element (for example the pivot point and pivot axis of parts such as the lever or parallel beam of a lever system of a Roberval mechanism) and which then cause performance limits of the load cell, yet still provide a satisfactory stiffness of the sensor body provided by the closing material boundaries of the monobloc sensor body, thereby enabling the measurement accuracy to be increased for a given sensor body shape.

[0011]

[0009] For example, the structure shown in DE19605087A1 has been found to have problems with rigidity and stability due to the slots cut into the monoblock body from above and below (height direction), respectively.

[0012] It will be appreciated that the closure material boundary closes in a direction relative to the heightwise end sides, but does not necessarily reach completely to the height of, for example, an essentially planar surface at the top or bottom of the body.

[0013]

[0011] In a preferred embodiment, the closed material boundary at least partially overlaps the mounting hole at its widthwise location. In an additional or alternative feature, the closed material boundary is present on one or both lateral sides of the monoblock body, whereby a material path is created extending from the female thread to a portion of the corresponding heightwise side end (upper or lower) of the body that is further inside the body than the cavity in the lengthwise direction, through the cavity to said heightwise side end, such a path having only a thin component in the widthwise direction or even no component at all. This further increases the rigidity and stability of the body.

[0014]

[0012] In a further preferred embodiment, the mounting portion has a width equal to or thinner than the width of the main body and, at least in the area not overlapping in width with the mounting hole, has the form of at least one larger "two-dimensional" handle body, in the sense that the same extension into a non-zero width of such a cross-section perpendicular to the width direction has the form of at least one larger (three-dimensional) handle body.

[0015]

[0013] In a further preferred embodiment, the cavity extends to one or both lateral sides of the monoblock sensor body. The cavity is an opening to the respective side. The lateral side of the body is one of the end sides in the width direction. That is to say, the cavity is open to the lateral side, in particular also to both lateral sides, thereby penetrating the monoblock sensor body in the width direction. This increases the solid angle when viewed in a protection perpendicular to the length direction and also allows the entry of a cutting element for cutting at least a part of the cavity penetrating the body.

[0016]

[0014] In a further preferred embodiment, the extension of the cavity in the height direction and / or of the side openings, when projected onto the height-length plane, covers a solid angle of more than 36°, preferably more than 42°, in particular more than 48°. This allows better coverage, especially for the mountings on the movable column side, even if the mounting holes are not arranged close to the corners of the body, but are offset axially (in the height direction) inwards. With respect to the centre of said solid angle, an axial position of the axial threaded end of the mounting hole axis is conceivable. However, for at least one or some mountings, such values ​​are preferred with respect to the centre of the mounting hole opening.

[0017] In this connection, it is also provided, according to a preferred embodiment, that the height distance between the mounting holes of the upper and lower mounting parts is less than 90%, preferably less than 80%, in particular less than 70% of the total height range of the monoblock body. Said distance between said mounting holes can be less than 60%, or even less than 55% or less than 50%.

[0018]

[0016] This applies in particular when the monoblock sensor is used in a load cell integrated into a weighing machine capable of measuring the weight of a product during its transport along the transport path, in particular in structures in which protective elements are provided between the movable column and the load-receiving member and / or intermediate parts or structures for coupling to the load-receiving member.

[0019]

[0017] In a further preferred embodiment, the cavity (particularly at its lateral side ends, i.e. also at its opening), has an elongated slit section, projected in a height-length plane, with a gap dimension perpendicular to the slit extension, in particular narrower than 2 mm, preferably narrower than 1.2 mm, in particular narrower than 0.8 mm, said slit section being produced in particular by a wire discharge mechanism. It is further preferred that said gap is narrower than 0.7 mm, preferably narrower than 0.6 mm, in particular narrower than 0.5 mm. However, the gap is understood to have a gap dimension which safely avoids contact between the two spaced apart side surfaces under normal load and stress conditions in the use of a load cell with the sensor body.

[0020]

[0018] In a further preferred embodiment, the cavity (in particular also its lateral sides) is provided with an enlargement (in particular in the basic form of a circular hole) having a gap diameter, projected in a height-length plane, larger than the slit, which allows the application of a preferred manufacturing mechanism in the form of wire erosion by introducing a wire through the enlargement, i.e. a wire discharge mechanism.

[0021]

[0019] In a further preferred embodiment, the monobloc sensor body has a first such attachment on the movable post, the allocated cavity of which covers both its nearest flexure point and at least a part of the coupling. In particular, it is provided that the protection from linear propagation paths protects the lower coupling mount for the coupling between the movable post and a first lever of the lever arrangement (which may comprise one or more levers, so that said first lever may be the only lever of the lever system, but further levers may be present).

[0022]

[0020] In a further preferred embodiment, the monoblock sensor body has parallel upper and / or lower beams with a length of at least 30%, preferably at least 36%, in particular at least 42% of the total length of the body. The total length of the body can generally be taken as the longitudinal distance between the end sides in the longitudinal direction, if the body is a parallelepiped, in particular a cube of general shape. However, in case of possible further geometric shapes, such as protrusions for mounting other parts of the electromagnetic force compensation mechanism or alignment protrusions of the (seat) surfaces around the mounting holes, the total length of the body 100 is defined as the distance between the average longitudinal positions of the seeking surfaces of the mounting holes of the movable and fixed columns when both mounting holes are provided in the longitudinal direction, otherwise the total length direction is defined as the average longitudinal distance along the height and width of the body of the monoblock sensor. In this respect, it is preferred that the mounting holes extend in the longitudinal direction, in particular for both the movable and fixed columns. However, the invention is generally not limited to the above-mentioned extension directions, other screwing directions can also be considered.

[0023]

[0021] In a further preferred embodiment, the cavity is connected with its assigned mounting hole(s), the junction of the cavity and the mounting hole being away towards the inside of the body with respect to the axial thread end, in particular with respect to the axial end of the female thread (slightly beyond but almost reaching the axial thread end, if the screw provided for mounting is designed such that its length fits the axial end of the female thread when fully screwed in). In this regard, the invention also provides for the arrangement of a monoblock sensor body having one or more of the features discussed above and a mounting assembly comprising a screw and defining the axial thread end of each mounting hole by the axial threaded connection of the distal thread end of the respective screw. The screw should not extend beyond the cavity. In particular, when the larger diameter part of the cavity is arranged in connection with the mounting hole, the cleaning process after the surface coating, if any, is more easily performed.

[0024]

[0022] In a further preferred embodiment, the monoblock sensor body has mounting holes at two different heights on each of the movable and fixed columns, in particular two mounting holes at each side and height, and a number of mounting parts, in particular all mounting parts, are screwed into the mounting holes with such cavities, which further increases the rigidity and reduces the stress propagation in some mounting parts, even to the more sensitive parts of the sensor body.

[0025]

[0023] In a further preferred embodiment, the cavities of at least two mounting holes having the same nearest flexure point are connected in the width direction, thereby forming a cavity area from one lateral end side of the body to the other lateral end side, which is advantageous for the manufacturing process and does not significantly affect the rigidity and stability of the monoblock sensor.

[0026]

[0024] In this respect, as already indicated above, the bridge width of the closed material boundary, preferably across the entire width of the monoblock sensor body, can also be narrower, but preferably the bridge width is at least 10%, preferably at least 20%, in particular at least 40% of the entire width and / or comprises at least two bridges, each with a bridge width of at least a material thickness equal to the thickness of the flexure point of the Roberval mechanism, and / or with the above percentage values.

[0027]

[0025] Depending on the height position of the mounting holes and other aspects of the overall design of the load cell, the material thickness of the closing material boundary in the height direction is appropriately set. However, the thickness of the flexure point should be at least 1 mm, or in particular at least 2 mm. That is, the presence of the closing material boundary creates more stability than the height thickness (which is, of course, sufficiently rigid in itself). It is understood that the arrangement of the closing material boundary in the height direction can and preferably should reach the height end of the overall contour of the body, but should reach a height position that is lower than 25% of the total height range of the body and / or lower than twice the thickness of the beam in the height direction, preferably lower than 15% of said total range and / or lower than 1.5 times the thickness of the parallel beam, in particular lower than 10% or 5% of the total height dimension and / or 0.75 times, even 0.5 times the beam thickness from the respective height end of the overall contour of the body.

[0028]

[0026] The present invention further provides a load cell having such a monoblock sensor body and an electromagnetic force compensation mechanism connected to the sensor body, it being understood that such a load cell also has a controller for the electromagnetic force compensation mechanism capable of indicating and controlling the current in the coil for generating the magnetic field for force compensation as a function of the lever position indicated by, for example, a mechanism / system position sensor.

[0029]

[0027] The present invention also provides a weighing device having one or more such load cells, it being understood that the weighing device may have one common controller for controlling the electromagnetic force compensation mechanisms of the respective load cells when there are multiple load cells incorporated therein.

[0030]

[0028] Furthermore, the present invention provides a method for manufacturing such a monoblock sensor body according to the manufacturing techniques already discussed, in particular the drilling and wire discharge mechanism. It is preferable that the same manufacturing techniques, at least partly the same manufacturing mechanisms, can be used for generating the cavity and for defining the structure of the monoblock sensor body with regard to its functional parts as the Roberval mechanism and the lever mechanism.

[0031] Further features, details and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0032] [Figure 1] FIG. 2 is a side view of the monoblock sensor body. [Diagram 2] FIG. 2 is a perspective view of a portion of a monoblock sensor body and an electromagnetic force compensation mechanism. [Diagram 3] 11 is an exploded view showing the attachment of the monoblock sensor body to the frame, and shows the attachment parts to the monoblock sensor body. FIG. [Figure 4] 1 in a cross-sectional view showing a connection between the lever mechanism of the sensor body and the electromagnetic force compensation mechanism, in another embodiment, similar to FIG. [Diagram 5] 1, but of yet another embodiment. FIG. [Figure 6] 1, but of yet another embodiment. FIG. [Figure 7] 1, but of yet another embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033]

[0030] In Fig. 1, a monoblock sensor body 100 is shown in a side view with mounting holes shown, the viewing direction corresponds to the width direction W, and the paper surface of Fig. 1 corresponds to the height-length plane. The sensor body 100 comprises a Roberval mechanism with a fixed post 20 and a movable post 10 connected to the fixed post 20 by parallel upper and lower beams 30 and 40, as can be easily recognized by a person skilled in the art. The bending of this parallel structure is shown by the flexure point 31 (upper left flexure point) between the movable post 10 and the upper beam 30, the flexure point 32 (upper right) between the upper beam 30 and the fixed post 20, the flexure point 41 (lower left) between the movable post 10 and the lower beam 40, and the flexure point 42 (lower right) between the lower beam 40 and the fixed post 20.

[0034]

[0031] Coupled to the movable column 10 by a connection with the lower connecting mount 51 is a lever arrangement 60 having, in the embodiment shown, three levers, namely a first lever 61, a second lever 62 coupled thereto, and a third lever 63 coupled to the second lever 62. However, it will be understood that such an embodiment having three levers is only one of several possible embodiments for the lever arrangement 60, which may consist of lever arrangements having only one lever, two levers, or even more than three levers.

[0035]

[0032] The third lever 63 can be connected, in a manner known to those skilled in the art, via a connecting element to an electromagnetic force compensation mechanism 200 (see FIG. 2), which comprises an electromagnetic force generator that generates an electromagnetic force that counteracts the displacement of the movable column of the body due to the load of the object to be measured. The load of the object to be measured is measured, for example, by the current required to generate a reaction force indicative of the weight of the load, in combination with a positioning sensor and a respective controller (not shown). The story of electromagnetic force compensation is well known to those skilled in the art and will not be further described here. Rather, for a more detailed description of the working principle of the electromagnetic force compensation mechanism, the disclosures of EP2397824B1 and DE19605087A1 are incorporated by reference.

[0036] The coupling of the third (last) lever 63 of the lever mechanism 60 can be better seen in Figure 4, where a connecting element is designated by the reference numeral 260. It will be appreciated that the connecting element 260 is attached by means of a screw guided through an opening in the fixed post 20 and screwed in the load direction to the lever 63. However, it will be understood that other types of connecting joints are also considered to be encompassed by the invention, such as, for example, a lateral extension arm attached laterally to the (last) lever and extending laterally of the body 100.

[0037]

[0034] In the embodiment shown in Fig. 1, the main body is provided with a protrusion 70 for supporting the electromagnetic force compensation mechanism 200. Of course, it is understood that the electromagnetic force compensation mechanism can be supported by other means, for example an external housing to which the fixed column 20 is attached. In the subject embodiment, the fixed column 20 is attached and fixed to the frame 300 of the weighing module having the monoblock sensor body 100 (Fig. 3) by inserting screws 91, 92 into the mounting holes 23, 23 arranged in the upper right mounting part 21 and the lower right mounting part 22 of the fixed column 20, respectively. The mounting holes 23, 23 extend in the length direction L, which is the extension direction of the parallel beams 30, 40. The mounting holes 23, 23 are provided with female threads 24, 24 to mate with the male threads (not shown) of the screws 91, 92 (Fig. 3). As can be seen from FIG. 3, in the subject embodiment, the upper right mounting portion 21 and the lower right mounting portion 22 are each provided with two mounting holes adjacent to each other in the width direction W at the same height in the height direction H.

[0038]

[0035] The mounting portion 21 has a mounting hole 23 located very close (in the height direction H) to the top end 101 of the main body 100, in this embodiment within 10% of the total height range of the main body. The mounting hole 23 of the lower right mounting portion 22 is located close to the bottom side surface 102 of the main body 100 in the height direction H, also located within 10% of the height range closest to the bottom end 102. Other height locations are possible, but preferably not more than 25% of the total height range, and more preferably not more than 20%.

[0039]

[0036] On the side of the movable column 10, the upper left mounting part 11 is provided in the upper half in the height direction H, and the lower left mounting part 12 is provided in the lower half. Of course, the height positions of the mounting holes can differ depending on what is to be attached, for example, an L-shaped connecting part. In particular, both mounting holes can also be arranged in the same upper or lower half, rather close to each other. Also, on this side, as can be better seen from Figs. 2 and 3, at the height of the upper left / lower left mounting parts 11, 12, two mounting holes 13 are provided with respective internal threads 14 to match the external threads of the fixing screws 81, 82. The mounting holes 13 have a surrounding seat 19 that protrudes slightly from the (longitudinal) side end 103 of the block 100.

[0040]

[0037] These fixing screws 81, 82 make it possible to fix the load receiver 310 to the movable column 10, between which a connecting piece 410, which may be in the form of a spacer, is inserted. The arrangement of the load receiver 310 is best shown in the cross-sectional view of Fig. 4 for an exemplary arrangement of a weighing module with the sensor body 100 in a weighing system where products are weighed during transport. It will be understood, however, that the subject invention is not limited to these applications and can be used in any kind of weighing system, including, for example, where the load receiver is a load plate for receiving weighing objects in a stationary state. The invention is not limited in this respect and the monoblock sensor body 100 can be used in any kind of load measurement system, electronic scales, in particular in weighing modules with high resolution.

[0041]

[0038] The load cell preferably corresponds to a high resolution, the ratio of resolvable increment to maximum load being better than 1 / 1000, preferably better than 1 / 5000, even better than 1 / 10000 or better than 1 / 50000.

[0042] As can be best seen in FIG. 2, the top end 101 of the longitudinal extension of the fixed post 20, as well as the longitudinal extension of the movable post 10, in this exemplary embodiment is free of any dents, slots or holes, as is the bottom end side 102, even though it is not visible in FIG. 2. Rather, the solid (bridged) portions 17, 27 are integral with the block body 100. This allows for a full retaining support over the entire height of the body, thereby providing good stability of the monoblock sensor body. However, a full material coverage on the top side 101, bottom side 102, respectively, is the preferred option, and partial slots, dents or lightening portions with material removed can be provided without essentially changing the structural integrity of the body in terms of rigidity.

[0043]

[0040] Despite this advantageous stability, the flexure points 31, 32, 41 and 42 as well as the lower connecting mount 51 and the connection between the first and second levers and the fulcrum of the second lever are still protected from mechanical stresses that may occur when the fixing screws 81, 82, 91 and 92 are screwed into the mounting holes 13, 23, in particular when tightened, because each mounting comprises a cavity 15, 16, 25, 26 respectively close to the mounting holes 13, 23 and even intersects said mounting holes 13, 23 in the exemplary embodiment.

[0044] In the illustrated exemplary embodiment, the main part of the heightwise extension of each of the cavities 15, 16, 25, 26 is formed by slits or slots. In this exemplary embodiment, these slots are formed by wire electric discharge machining, i.e. an erosion process. Thus, first holes 15, 25 are provided extending completely through the entire width of the sensor body 100 in the width direction W, through which wires can be inserted to produce the slits 16, 26, respectively. As can be seen from the way in which the slits 16, 26, as well as these slots in the material of the sensor body 100 defining the beams 30, 40 and the lever substructure of the lever arrangement 60, are depicted, the same manufacturing techniques can be used to define the shape of said substructures of the sensor body.

[0045] However, it will be appreciated that such slots can also be machined by a suitable cutting tool such as a rotating cutting disk, or by other chipping materials or any other type of metal cutting technique, for example milling. Also, water jet cutting or laser cutting may be used.

[0046]

[0043] When viewed in the height-length plane (the plane of the paper in Fig. 1), the respective projections of the solid angles subtended by the cavities 15, 16 are approximately 80° when the center of measurement of the solid angle is set at the mounting hole entrance of the longitudinal end 103 of the body 100, and close to 120° when said center is set at the axial thread end, which is a longitudinal distance Δl from the left longitudinal end 103 of the sensor body 100. This allows for linear propagation paths originating from the threads, and in particular the thread end, to be stopped, for example, by the cavity 16 of the cavity of the mounting portion 12, and similarly the other flexure points are protected by the cavities of the other mounting portions.

[0047] It will be understood that the shape of the cavities is not limited to that shown in FIG. 1. For example, the slots may be curved or axially displaced in the length direction relative to the state shown in FIG. 1 in order to effectively protect against the same solid angle. However, it is preferred to connect the mounting holes 13, 23 to the respective cavities 15, 16, 25, 26. Moreover, the cavities protecting the flexure points and other sensitive parts of the sensor body do not need to be connected in the width direction, as is the case in the exemplary embodiment shown, also in view of the preferred manufacturing technique. The mounting cavity can also be composed of two or more single cavities that are not connected to each other, but still protect the sensitive elements blocked thereby from the stress transmission of the direct propagation path. Some other examples of cavities are shown in FIG. 5, FIG. 6, and FIG. 7.

[0048]

[0045] For the cavities 25, 26 of the mounting parts of the fixed post 20, the positions of the threaded ends and the cavities are substantially coincident in the longitudinal position, resulting in a coverage angle of about 180° in the projection onto the height-length plane. Furthermore, although the mounting holes 23 are in the illustrated embodiment much closer to the end sides 101, 102, respectively, compared to their arrangement on the mobile post 10 side, there is still a material of height thickness Δh1, Δh2, respectively, which allows the retention force path starting from the mounting holes to pass to the upper side 101 by bypassing the cavities 25, 26 of the upper right mounting part 21 to the upper side 101, and from the mounting holes 23 of the lower right mounting part to reach the lower end 102 by bypassing its assigned cavities 25, 26 downwards.

[0049]

[0046] These paths available for carrying the forces according to the invention are provided at least over a bridge width wb of the widthwise extension of the cavity, despite the presence and protective effect of the cavity for the sensitive part of the sensor body. In the embodiment shown, the bridge width wb is equal to the total width wt, but it can also be narrower (see above).

[0050]

[0047] In the perspective view of Fig. 2, the electromagnetic force compensation mechanism 200 supported by the protrusion 70 is also shown. Furthermore, the linear propagation paths P1 and P2 are shown as the closest paths that are not blocked by the cavity 16. It is recognized that the upper one of these paths, P1, reaches the upper end side 101 before the upper left flexure point 31, when viewed in the length direction, and is therefore protected. Also protected is the lower coupling mount 51 that couples the movable column 10 to the first lever 61, and the first linear propagation path P2, which bypasses the cavity 16 below, reaches said mount 51, but in alternative embodiments, it can also be blocked by the slit 16 of the mounting part 11 extending further downwards or curving (see, for example, Fig. 5). The same is true of the propagation path not shown that starts from the threaded end of the lower left mounting part 12 for the upper end side 101, and the linear propagation path starting there for the lower end side 102 also does not reach the lower left flexure point 41.

[0051]

[0048] It is understood that the extension of the cavity may vary with the height position of the mounting holes 13, 23 and / or the height position of the center of the cavity relative to the height position of the mounting hole 13 may vary depending on the absolute height position of the mounting hole 13 relative to the upper end side 101 relative to the mounting portions 11, 21 and the lower end side 102 relative to the lower mounting portions 12, 22.

[0052]

[0049] In Fig. 5, which is a similar view to Fig. 1, a further embodiment of the invention is shown. For the most part it is identical to the embodiment of Fig. 1 and will not be described again. The embodiment of Fig. 5 differs from Fig. 1 in the shape / extension of the slit portions 16, 26 of the cavities 15, 25 and the position of the hole 25. Here, a curved configuration is provided for the slot portion 16, which still covers approximately the same solid angle as the embodiment of Fig. 1.

[0053] 6 and 7, a cavity arrangement is recognized with a broken partial cavity on the side of the movable post 10. Thus, as can be recognized from the embodiments of figures 1, 5, 6 and 7, some modifications of the position and shape of the cavities covering the sensitive elements of the monoblock body 100 can still be made while keeping the satisfactory rigidity and stability provided by the closing material interface 17, 27.

[0054]

[0051] Moreover, it will be understood that the detailed features of the illustrated embodiments do not limit the scope of the subject invention, but rather the features of the foregoing description and of the following claims may be essential to the invention either alone or in any combination in its various embodiments. [Explanation of symbols]

[0055] 10 Movable pillar 11, 12 Mounting part 13 Mounting hole 14 Female thread 15 Cavity 16 Cavity 17 Closed material boundary 19 seats 20 Fixed column 21, 22 Mounting part 23 Mounting hole 24 Female thread 25 Cavity 26 Cavity 27 Closed material boundary 30 Upper parallel beam 31, 32 Upper flexure point 40 Lower parallel beam 41, 42 Lower flexure point 51 Lower Joint Mount 60 Lever structure 61 First Lever 62 Second Lever 63 The Third Lever 64 Second Lever Pivot 70 Protrusion 81, 82 Screws 91, 92 Screws 100 Monoblock sensor body 101 Upper side 102 Lower side 103 (of movable column) longitudinal side 105 Lateral side 200 Electromagnetic force compensation mechanism 260 Connection Elements 300 Housing Frame 310 Load-bearing members 410 Connection parts H Height direction / load direction W Width direction / horizontal direction L Length direction Δl Length dimension Δh1, Δh2 Height dimensions wb Width dimension wt Overall width P1, P2 transmission route

Claims

1. A monoblock sensor body (100) of a load cell based on an electromagnetic force compensation mechanism (200), said sensor body comprising: The Roberval mechanism, a lever arrangement (60) having one or more levers (61, 62, 63) with respective fulcrums (64), which are connected on one side by a connection to the movable column (10) of the Roberval mechanism and are connectable on the other side to the electromagnetic force compensation mechanism; Mounting parts (11, 12, 21, 22) for mounting the fixed column (20) of the Roberval mechanism directly or indirectly via an intermediate structure to a housing side part (300) of a weighing module and / or for mounting a load receiver (310) to the movable column (10) directly or via an intermediate structure, at least one of which comprises: At least one mounting hole (13, 23) extending along the length direction (L) of the parallel upper beam (30) and lower beam (40) of the Roberval mechanism, which are at least mainly perpendicular to the load direction (H) and connected to the fixed column and the movable column via a first upper flexure point (31) and a first lower flexure point (41) and a second upper flexure point (32) and a second lower flexure point (42), respectively, the mounting hole having a mating female thread (14, 24) so ​​that the male thread of a fixing screw (81, 82, 91, 92) that is screwed into the mounting hole in a state where it is mounted in the mounting hole up to the threaded end in the axial direction can be screwed into the mounting hole, and the mounting hole has one of the first upper flexure point (31), the second upper flexure point (32), the first lower flexure point (41), and the second lower flexure point (42) as a relatively nearest flexure point. A mounting portion (11, 12, 21, 22) having In a monoblock sensor body comprising: A monoblock sensor body (100), characterized in that at least one mounting portion has a cavity (15, 16; 25, 26) that reduces the available solid angle of a straight-line propagation path extending from the female thread to one or more of a nearest flexure point, a bond, and a nearest fulcrum, while a closing material boundary (17; 27) of the sensor body (100) closes the cavity (15, 16; 25, 26) over at least a bridge width (wb) to the upper and lower ends (101; 102) of the sensor body corresponding to the nearest flexure point (31, 32; 41, 42).

2. 2. The monoblock sensor body of claim 1, A monoblock sensor body, wherein the closing material boundary (17; 27) at least partially overlaps the mounting hole when viewed in the load direction (H).

3. 3. A monoblock sensor body according to claim 1, The monoblock sensor body, wherein the cavity extends along the direction of the bridge width (wb) to a side surface (105) of the monoblock sensor body.

4. A monoblock sensor body according to any one of claims 1 to 3, A monoblock sensor body in which the extension of the cavity and / or side opening in the height direction same as the load direction (H) covers a solid angle greater than 36° when projected onto a plane extending in the height direction and the length direction (L).

5. 5. The monoblock sensor body of claim 4, A monoblock sensor body, wherein the side opening and / or cavity has an elongated slit portion (16; 26) having a gap dimension perpendicular to the slit extension, when projected onto the plane, of less than 2 mm, and the slit portion is manufactured by a wire discharge mechanism.

6. 6. The monoblock sensor body of claim 5, A monoblock sensor body, wherein the side opening and / or the cavity comprises an enlargement (15; 25) of the basic form of a circular hole with a larger gap diameter than the slit portion, as projected onto the plane.

7. A monoblock sensor body according to any one of claims 1 to 6, A monoblock sensor body having a first said mounting portion (11; 12) on said movable column, the assigned cavity (15, 16) of which covers both its nearest flexure point (31; 41) and at least a part (51) of said coupling portion.

8. A monoblock sensor body according to any one of claims 1 to 7, A monoblock sensor body, wherein the length of the parallel upper and lower beams is at least 30% of the overall length of the sensor body (100).

9. A monoblock sensor body according to any one of claims 1 to 8, A monoblock sensor body, wherein the cavity is connected to its assigned mounting hole, and the junction of the cavity and the mounting hole is spaced toward the interior of the sensor body relative to the axially threaded end.

10. A monoblock sensor body according to any one of claims 1 to 9, The monoblock sensor body has mounting holes (13; 23) at two different height positions on each of the movable column (10) and the fixed column, and a plurality of mounting portions (11, 12; 21, 22) associated with the mounting holes (13; 23) have the cavities.

11. A monoblock sensor body according to any one of claims 1 to 10, A monoblock sensor body, in which the cavities of at least two mounting holes having the same nearest flexure point are connected in the width direction, thereby forming a cavity (15, 16; 25, 26) reaching from one lateral end side (105) of the sensor body to the other lateral end side.

12. A load cell (100, 200), A load cell (100, 200) comprising a monoblock sensor body (100) constructed according to any one of claims 1 to 11 and an electromagnetic force compensation mechanism (200) connected to the lever arrangement (60) of the sensor body (100).

13. A weighing device comprising one or more load cells configured according to claim 12, the weighing device having a load receiving member (310) fixedly attached directly or indirectly to the movable column (10) of the monoblock sensor body (100) of the load cell.

14. A method for manufacturing a monoblock sensor body constructed according to any one of claims 1 to 11, comprising the steps of: The method includes creating the cavity by material removal while leaving the closed material boundary of the sensor body.

15. 15. The method of claim 14, defining the Roberval mechanism and / or lever mechanism in the monobloc sensor body by material removal; The material removal of the generating and / or defining steps preferably comprises: a first step of cutting a first cavity (15; 25) to accommodate the wire of a wire discharge mechanism and then extending said cavity by creating one or more slits (16; 26) on one or both sides in said loading direction (H) by erosion with a wire discharge mechanism, or The method comprises cutting said cavities (15, 16; 25, 26) using water jet cutting.

16. The monoblock sensor body of claim 1, A monoblock sensor body, wherein the closing material boundary (17; 27) at least partially overlaps the mounting hole at a position along the direction of the bridge width (wb).

Images