Device for determining the weight of a measuring object

Abstract

A device comprising a support device (6) and a load cell (1) for determining the weight of a measurement object (2), wherein the load cell (1) consists of a base body (3), a deformation section (5), and at least one measuring element (4) which is present in or on the deformation section (5) of the load cell (1) which can be deformed by the action of a weight force of the measurement object (2), and the measuring element (4) generates an electrically measurable output signal corresponding to the deformation, which can be processed in an evaluation electronics, wherein the deformation section (5) present on the base body (3) of the load cell (1) and which receives the weight of the measurement object (2) is coupled to a support device (6), which is or has a lifting device, by means of whose change in length the measurement object (2) can be transferred from an initial position to a weighing position, characterized in thatthat the deformation section (5) projects into a free space (7) formed by a ring shape of the base body (3), wherein the base body (3) has at least one connecting flange (8, 9) for fastening the load cell (1) to the measuring object (2), and the base body (3) with the deformation section (5) formed thereon and the at least one connecting flange (8, 9) likewise formed on the base body (3) form a one-piece component.

Description

[0001] The invention relates to a device for determining the weight of a measuring object according to the preamble of patent claim 1.

[0002] Weight measurement plays an important role in many areas of life. For example, in agriculture or the construction industry, load cells are used to record the weight of a silo container because they are relatively robust and can measure even heavy weights very precisely. A corresponding load cell is arranged under each leg of such a silo container. By constantly monitoring the weight of the silo, the time when the contents need to be refilled can be determined. Furthermore, such a load cell can also be used to easily record the consumption of the supplies stored in the silo container or container. Load cells are therefore a component of well-known weight recording devices. Furthermore, load cells are also generally used in personal, animal, or vehicle scales, for example. Their range of applications is extremely diverse.The structure of a load cell is relatively simple. It comprises a base body into which at least one measuring element is integrated. The measuring element is a measuring element that reacts to deformation. Strain gauges are mentioned here merely as an example, although other measuring elements are also known. The load cell further comprises at least one deformation section that deforms due to the weight acting on it and thus generates an electrically measurable output signal via the measuring element that corresponds to the deformation. This output signal can be processed in evaluation electronics designed for this purpose and equipped with suitable software or interacting with it. To enable evasive movements of the deformation section, load cells of known designs have a deformation gap, often designed as a deformation slot, between the deformation section and a corresponding counter surface.Shear beam load cells are currently the most commonly used load cells. Of course, there are also other designs that differ in the geometry of the base body and process the applied weight forces differently. T-shaped or S-shaped load cells are just a few examples.

[0003] A known shear beam load cell is disclosed, for example, in EP 0 952 436 A2. In the solution described in the document, several load cells are placed beneath a container for holding agricultural products. For this purpose, the container must be lifted by means of a crane before the load cells are arranged, which is very complex and, not least, costly due to the heavy weight of such a container, which can be more than 10 t. In this solution, each of the load cells used consists of a base body, an additional, movable platform, and a separate deformation section that accommodates the platform. A bearing pin is also inserted into the platform, which ultimately rests against the underside of the container and thus supports the container.The container can be moved by approximately 1 to 2 mm from an initial position to a weighing position by securing several bolts, i.e., lifted by closing a gap between the deformation section and the base body that existed before the bolts were secured. The deformation section, with its contained load cell, forms a separate component that is connected to the base body in an additional work step and secured to it in the manner described above. The solution presented in this publication consists of numerous individual parts, is therefore very complex to manufacture, and requires considerable assembly effort.

[0004] US 10,416,019 B2, on the other hand, presents a load cell with an S-shaped base body geometry. This load cell is housed in an A-shaped frame fixed to the substrate, which also has a support block that is attached laterally to a measuring object standing on a substrate, for example, to the leg of a silo container. The S-shaped load cell is inserted between the frame and the support block, and a screw bolt penetrating the frame is screwed into its upper leg. This bolt also serves to accommodate the load cell in the frame at an adjustable height. By rotating the screw bolt, the measuring object can thus be indirectly lifted, subjecting the load cell to a tensile load, since the lower leg of the load cell is fixed to the support block.This design variant is very complex due to the large number of individual components and in particular because of the required frame.

[0005] US 4,065,962 describes a load cell for determining the weight of a measurement object. The load cell consists of an annular base body and at least one measuring element located in or on a deformation section that can be deformed by the weight of the measurement object. The measuring element provides an electrically measurable output signal corresponding to the deformation, which can be processed in an evaluation electronics system. In this load cell, the deformation section is connected to the base body via a web, and the load to be measured is transferred to the deformation section via a frame element, which in turn is connected to the base body.

[0006] US 10,921,178 B2, however, discloses a weight measurement device in which the base body of the load cell is attached directly to the measurement object. A shear beam load cell is used as the load cell. A threaded bolt serves as the lifting device, with the threaded bolt being screwed through a thread in the base body of the load cell. The threaded portion of the threaded bolt rests on the surface. The load cell is also mounted in a holder so it can rotate about a pivot axis and can be raised or lowered together with the measurement object using the threaded bolt. The load cell performs a circular arc movement around the pivot axis. To fix the load cell at a desired height, an additional fixing bolt is required. This bolt is guided through another hole in the base body of the load cell and must be secured with an additional cotter pin.

[0007] The functionality of a load cell for determining the weight of a silo container is also described in DE 10 2011 106 851 A1. In this document, a soft, elastic material is inserted into the deformation gap between the substrate and the deformation section of the load cell, thus protecting the weight-sensing device from the effects of weather.

[0008] The invention is based on the object of providing a device for determining the weight of a measuring object, which is overall simple and compact in design and thereby brings about a reduction of the measuring errors and the lowest possible load on the measuring object.

[0009] The invention solves this problem with the features of patent claim 1. Further embodiments of the invention are the subject of the subsequent subclaims.

[0010] A device comprising a support device and a load cell for determining the weight of a measurement object, wherein the load cell consists of a base body, a deformation section and at least one measuring element which is present in or on the deformation section of the load cell which is deformable by the action of a weight force of the measurement object and the measuring element generates an electrically measurable output signal corresponding to the deformation, which can be processed in an evaluation electronics and the deformation section present on the base body of the load cell and which receives the weight of the measurement object is coupled to a support device which is or has a lifting device, by means of whose change in length the measurement object can be transferred from an initial position to a weighing position, was further developed according to the invention in such a way that the deformation section projects into a free space formed by a ring shape of the base body,wherein the base body has at least one connecting flange for fastening the load cell to the measuring object and the base body with the deformation section formed thereon and the at least one connecting flange also formed on the base body form a one-piece component.

[0011] The key advantage of the solution according to the invention is that the load cell has an extremely simple and compact design. A preferred embodiment is one in which the base body, the deformation section formed thereon, and the at least one connecting flange, which is also integrally formed on the base body, form a single-piece component. However, it is particularly preferred to provide multiple connecting flanges. The load cell is attached to the measurement object via this connecting flange in a particularly advantageous manner using a detachable connection, allowing the load cell to be replaced if necessary. The deformation section is connected to the base via the support device, so that the weight of the measurement object permanently acts on the deformation section via the connecting flanges.In the simplest case, the connecting flanges consist of a web formed from the base body, into which a hole or thread is made on the front side, i.e. on the side facing the measuring object.

[0012] whereby the detachable connection to the measuring object can be created if a corresponding bolt, pin or rivet is present on the measuring object or is inserted into the measuring object. However, the connecting flanges can also be provided with at least one through-hole, for example, transverse to their longitudinal extent, so that this through-hole serves for the detachable fixation of the load cell to the measuring object, for example by a screw, a bolt or a rivet being guided through this through-hole and connected to the measuring object or by such a bolt, rivet or a screw being inserted into the

[0013] A measuring object is present onto which the connection flanges can be placed. A further, essential aspect of the invention is that the base body of the load cell can be fastened directly or indirectly to the measuring object, which is particularly advantageously also possible retrospectively, i.e. when the measuring object is already present and / or set up. Furthermore, it was found that by fixing the measuring object to the connection flanges on the measuring object, which run equidistant and parallel to one another in the unloaded state, a very low bending moment is created, which leads to less stress in the sense of deformation of the measuring object and thus to more precise measurement results than was the case with previously known load cell designs.This advantage is particularly due to the short distance between the surface of the measurement object and the connection point with the deformation section, as this distance is smaller than, for example, with beam load cells, which have a relatively long lever arm and thus a greater distance from the connection point. If the load cell according to the invention features two connecting flanges connected by a web, the overall stability of the load cell is increased, while at the same time it is very compact, which also makes a significant contribution to improving the achievable measurement accuracy. The base body of the load cell according to the invention has a ring shape when viewed from the side.The load cell can therefore be protected from contamination or weather influences, for example, by simple encapsulation or by attaching or attaching a cover, which is particularly useful for outdoor use. To ensure that the weight of the measuring object can act unrestrictedly and permanently on the deformation section in order to implement a permanent measurement of the weight of the measuring object, the support device coupled to the deformation section is a lifting device or has a lifting device by means of whose change in length the measuring object can be transferred from an initial position to a weighing position. In other words, the measuring object is connected to the load cell via the connecting flanges and then the deformation section is used to transfer the measuring object to a defined height so that the weight of the measuring object acts directly on the deformation section.In this way, the load cell can, for example, be attached to the side of a test object placed on a base, so that the lifting device coupled to the deformation section rests on the base with its side facing away from the deformation section or is anchored in the base. The anchoring does not have to be below the test object, but can particularly advantageously be provided laterally next to the test object, which significantly simplifies installation, i.e., the connection of the load cell to the test object. The lifting device can particularly advantageously be designed to be hydraulically, pneumatically, electrically, electromagnetically, or mechanically extendable, i.e., adjustable in length. The choice of one or the other means for changing the height of the test object depends on the local conditions and the available resources.A mechanically extendable device is particularly simple and stable. Furthermore, a mechanical lifting device does not require hydraulic or pneumatic lines, electrically conductive connections, or power sources. The through-openings in the connecting flanges can preferably be incorporated into the connecting flanges in such a way that the through-openings run along a plane spanned by the connecting flanges and the deformation section.

[0014] According to a first embodiment of the invention, it is proposed that the base body of the load cell, on the connection side with the measurement object, has a connection contour with two parallel connection flanges, wherein at least one of the connection flanges has a through-hole through which at least part of the support device coupled to the deformation section is guided. In a particularly preferred embodiment, both connection flanges each have a through-hole, thus simplifying the assembly of the support device. In the simplest case, the through-hole can be a through-hole.

[0015] Since the base body of the load cell according to the invention has an overall ring shape, a further development of the invention provides that the end face of the connection flanges, which is to be regarded as the connection contour, i.e., the side that is connected to the measurement object, has a web connecting the connection flanges to one another. This connection between the connection flanges creates an overall ring-shaped contour of the base body, which significantly determines the compact design of the load cell according to the invention. The deformation section protrudes into the free space formed within the ring in a manner that allows its deformation unhindered due to the weight of the measurement object acting on the deformation section.

[0016] A particularly simple embodiment of a load cell according to the invention can be seen in that the deformation section has an annular flange on which, when the lifting device is mounted, a corresponding pressure flange of a pressure sleeve of the lifting device slides, wherein a threaded bolt of the lifting device is screwed into the pressure sleeve, the threaded bolt being fixed to the base with its opposite end, anchored in the base or supported on the base.

[0017] As an alternative to this proposal, however, it is also advantageous if the deformation section has an internal thread into which a corresponding threaded bolt of the lifting device is screwed when the lifting device is installed. The bolt rests on the subsurface with its end opposite the thread or is anchored in the subsurface. These mechanical solutions are both resistant to weather influences and, moreover, easy to handle. A power supply or hydraulic or pneumatic lines are unnecessary.

[0018] If the mechanical design of a weight measurement device features a threaded bolt, the end opposite the thread of the threaded bolt can terminate in a base, which is designed, for example, as a ball joint. The ball joint design allows for movement to be compensated for, thus significantly simplifying the assembly of the entire weight measurement device.

[0019] The invention is explained in more detail below with reference to the accompanying drawings. The exemplary embodiments shown do not represent a limitation to the variants shown, but serve merely to explain a principle of the invention.

[0020] Identical or similar components are always designated by the same reference numerals. To illustrate the functionality of the invention, the figures show only highly simplified schematic diagrams, omitting components that are not essential to the invention. However, this does not mean that such components are not present in a solution according to the invention.

[0021] It shows: Fig. 1: a side view of a load cell with a very special type of mounting, Fig. 2: a view according to arrow II from Fig. 1 on the load cell Fig. 1, Fig. 3: a section through a first embodiment of a load cell fixed to a measuring object with a compared to the illustration in Fig. 1 different mounting and in a weighing position of the measuring object, Fig. 4: a section through a second embodiment of a load cell attached to a measuring object in a weighing position of the measuring object and Fig. 5: a spatial representation of a load cell according to the explanations in the Fig. 3 and Fig. 4.

[0022] in the Fig. 1 shows a load cell 1 according to the invention, which essentially consists of a base body 3, which in the present case is of an annular polygonal design. Due to the annular shape of the base body 3, it has a high degree of stability, so that the load cell 1 can be designed very compactly. In the center of the base body 3, there is a free space 7, into which the deformation section 5 of the load cell 1 projects, so that the deformation section 5 can deform unhindered due to the weight acting on it via a measuring object 2. Due to the deformation of the deformation section 5, an electrical output signal is generated in the measuring element 4, which in the present case forms a component of the deformation section 5, which electrical output signal is transmitted to a downstream and in the Fig. 1 is further processed and evaluated by evaluation electronics not shown. The base body 3 of the load cell 1 shown here also includes two parallel connecting flanges 8 and 9, which serve to connect to the measuring object 2 and are in turn connected to each other by a web 12, so that the aforementioned ring shape of the base body 3 is created. A special feature of the design variant of a load cell 1, as shown in Fig. 1, consists in the fact that two fastening holes 28 are provided in each of the parallel connecting flanges 8, 9, which completely penetrate the connecting flanges 8, 9 and serve for the detachable fixing of the load cell 1 to the measuring object 2. For the fixing of the load cell 1 to the measuring object 2, in the simplest case, Fig. 1, screw bolts (not shown) are used, which are guided through the fastening holes 28 and screwed into a corresponding thread of the measuring object 2. The fastening of the load cell 1 is thus carried out along the longitudinal side of the connecting flanges 8 and 9, whereby the fastening holes 28 penetrate the connecting flanges 8 and 9 transversely to their longitudinal extent. The weight of the measuring object 2 is transmitted via the connecting flanges 8, 9 into the base body 3 and thus indirectly to the deformation section 5, which is located on or in a Fig. 1 not shown. In the illustration of the Fig. 1, for the sake of simplicity, the illustration of a support unit 6 which can be used for this purpose and is connected to the deformation section 5 was omitted.

[0023] In conjunction with the Fig. 2, which shows the view of the load cell 1 according to the arrow II of Fig. 1 shows, it becomes clear how the deformation section 5 is connected to the measurement object 2. Coaxial through-openings 10 and 11, respectively, are introduced into the connecting flanges 8 and 9, which in the present case are through-holes and which run at a distance from and in an intersecting manner to the previously mentioned fastening holes 28, wherein the through-openings 10, 11 and the fastening holes 28 are aligned perpendicular to one another in a special case. A support device 6 is inserted into the through-openings 10, 11, which can, for example, be a lifting device to be described in more detail below. The support device 6, which stands with its lower end on the substrate 16 or is fixed in the substrate 16, is directly coupled to the deformation section 5, which is shown below in the illustrations of the Fig. 3 and Fig. 4 is more clearly visible.

[0024] The Fig. 3 shows a section through a load cell 1 attached to a measuring object 2 in a weighing position of the measuring object 2. “Weighing position” in the present sense means that the measuring object 2 is in the direction of the Fig. 3 is raised from the base 16 and thus has a distance B from the base 16. The load cell 1 therefore carries the measuring object 2 and initially has a base body 3, on which a deformation section 5 is formed as a single piece. The deformation section 5 is deformed by the weight of the measuring object 2 acting on it, whereby an electrical output signal is generated in a measuring element 4 integrated in the deformation section 5, which can, however, also be attached to the surface of the deformation section 5, which electrical output signal is in a Fig. 3 is processed by evaluation electronics not shown, i.e., it can be converted into a value corresponding to the weight of the measuring object 2 and further processed or displayed. Furthermore, on the base body 3 of the load cell 1, there are two connecting flanges 8 and 9 arranged at a distance from one another and running parallel to one another, which serve to fasten the load cell 1 to the measuring object 2 and are also formed integrally with the base body 3. The connecting flanges 8, 9 have on their front sides, i.e. on their side facing the measuring object 2, each in the Fig. 3 unspecified threads, into each of which a corresponding screw bolt 19 or 20 is screwed, which is fixed to the measuring object 2, so that the fixation of the load cell 1 to the measuring object 2 is possible. Between the connecting flanges 8, 9, the load cell 1 in the present case has a web 12 which, in the example shown, rests on the surface of the measuring object 2 when the latter is connected to the load cell 1. As a result, the base body 3 of the load cell 1 forms an overall, in this case polygonal, ring shape with a free space 7 formed within the ring, into which the deformation section 5 projects and can be deformed as a result of the weight of the measuring object 2 acting on the deformation section 5.

[0025] The assembly of the load cell 1 takes place in the Fig. 3, a ground anchor 21 is first fixed in the substrate 16. The ground anchor 21 is a screw bolt screwed into the substrate 16, which, above the substrate 16, extends into a fastening eye 22 into which another screw bolt 23 is screwed. With this type of fastening, the screw bolt 23 fixes a threaded bolt 17, onto whose thread a pressure sleeve 15 is screwed. The pressure sleeve 15 is guided through a through-opening 10 in the connecting flange 8, which is perpendicular to the longitudinal extension of the connecting flanges 8, 9, i.e. here vertically extending, and through a coaxial through-opening 11 in the connecting flange 9 and has, in the region of the deformation section 5 of the load cell 1, a pressure flange 14 which slides against a corresponding annular flange 13 of the deformation section 5.A relative movement between the pressure sleeve 15 and the threaded bolt 17 causes the pressure sleeve 15 and the threaded bolt 17 to move into or apart from each other, thereby generating a lifting movement. The relative movement of the pressure sleeve 15 in relation to the threaded bolt 17 is initiated in the manner shown in . Fig. 3, via a hexagon nut 24 at the upper end of the pressure sleeve 15. The threaded bolt 17 and the pressure sleeve 15, in conjunction with the deformation section 5, form a lifting device 6, which, together with the load cell 1, enables a lifting movement of the measuring object 2, so that a continuous measurement of the weight of the measuring object 2 can be carried out. On the underside of the base body 3 of the load cell 1, there is also a cable connection 25, which in this case enables the connection to the evaluation electronics.

[0026] The Fig. Figure 4 illustrates an alternative design variant of a load cell 1. Here, too, the load cell 1 consists of a base body 3, on which the deformation section 5 with a measuring element 4 contained therein, as well as two parallel connecting flanges 8 and 9 with a web 12 between the connecting flanges 8, 9, are integrally formed. As a result, the base body 3 of the load cell 1 also forms a ring shape with a free space 7 formed within the ring, into which the deformation section 5 projects. In each of the connecting flanges 8, 9 fixed to the measuring object 2 by means of screw bolts 19 and 20, a through-opening 10, 11 is made which is aligned vertically to the longitudinal extent of the connecting flanges 8, 9 and whose diameter is also larger than the diameter of the threaded bolt 17 which was screwed into a corresponding internal thread 18 of the deformation section 5.On its side facing away from the thread, the threaded bolt 17 also has a hexagon nut 26, which is shown in the illustration in . Fig. 4 rests with its contact surface on a base 27. The base 27 is designed as a ball joint in this case to compensate for movements. A rotational movement of the threaded bolt 17 generates a relative movement between the internal thread 18 in the deformation section 5 and the threaded bolt 17 screwed therein, which leads to a lifting movement of the lifting device 6 formed thereby. In this way, the measuring object 2 can be lifted in the direction of arrow A, so that the measuring object 2 has a distance B from the base 16 in the weighing position.

[0027] From the Fig. 5 shows a spatial representation of a load cell 1, as it is used as an example in connection with the description of the Fig. 3 and Fig.4 has already been explained. The rod- or beam-like connecting flanges 8 and 9 serve to fasten the load cell 1 to the measuring object 2. In this case, this is done via internal threads present on the end face, i.e., on the side of the web 12 connecting the connecting flanges 8 and 9, in the connecting flanges 8, 9, into which corresponding threaded bolts can be screwed. The base body 3 of the load cell 1 is designed as a polygonal, ring-shaped body, on which the deformation section 5 is formed in one piece and projects into the free space 7 of the base body 3, so that the deformation section 5 can deform unhindered due to the weight of the measuring object 2 acting on it. In the example shown, the measuring element 4 is also located in the deformation section 5. LIST OF REFERENCE SYMBOLS: 1 load cell 2 Measuring object 3 basic bodies 4 measuring element 5 Deformation section 6 Carrying device 7 Free space 8 Connection flange 9 Connection flange 10 passage opening 11 Passage opening 12 jetty 13 Ring flange 14 Pressure flange 15 pressure sleeve 16 Underground 17 threaded bolts 18 internal threads 19 screw bolts 20 screw bolts 21 ground anchors 22 Mounting eye 23 screw bolts 24 hexagon nut 25 cable connection 26 hexagon nut 27 Stand (ball joint)

Claims

[1] A device comprising a support device (6) and a load cell (1) for determining the weight of a measurement object (2), wherein the load cell (1) consists of a base body (3), a deformation section (5) and at least one measuring element (4) which is present in or on the deformation section (5) of the load cell (1) which is deformable by the action of a weight force of the measurement object (2), and the measuring element (4) generates an electrically measurable output signal corresponding to the deformation, which can be processed in an evaluation electronics, wherein the deformation section (5) present on the base body (3) of the load cell (1) and which receives the weight of the measurement object (2) is coupled to a support device (6) which is or has a lifting device, by means of whose change in length the measurement object (2) can be transferred from an initial position to a weighing position, characterized byin that the deformation section (5) projects into a free space (7) formed by a ring shape of the base body (3), wherein the base body (3) has at least one connecting flange (8, 9) for fastening the load cell (1) to the measuring object (2), and the base body (3) forms a one-piece component with the deformation section (5) formed thereon and the at least one connecting flange (8, 9) likewise formed on the base body (3). [2] Device according to claim 1, characterized by that the base body (3) of the load cell (1) has, on the connection side with the measuring object (2), a connection contour with two connecting flanges (8, 9) parallel to one another, wherein a through opening (10, 11) is introduced into at least one of the connecting flanges (8, 9), through which at least part of the support device (6) coupled to the deformation section (5) is guided. [3] Device according to claim 2, characterized bythat the connection contour has, on its side facing the measuring object (2), a web (12) connecting the connection flanges (8, 9) to one another. [4] Device according to one of the preceding claims 1 to 3, characterized by in that the deformation section (5) has an annular flange (13) against which a corresponding pressure flange (14) of a pressure sleeve (15) of the lifting device (6) slides when the lifting device (6) is mounted, wherein a threaded bolt (17) of the lifting device (6) is screwed into the pressure sleeve (15), the threaded bolt being fixed to the base (16) with its opposite end, anchored in the base (16) or supported on the base (16). [5] Device according to one of the preceding claims 1 to 3, characterized bythat the deformation section (5) has an internal thread (18) into which, when the lifting device (6) is mounted, a corresponding threaded bolt (17) is screwed, which is fixed to the base (16) with its end opposite the thread, is supported on the base (16) or is anchored in the base (16).

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