load cell

Abstract

Load cell (1) for determining the weight of a measured object (2), wherein the load cell (1) consists of a base body (3) and at least one measuring element (4) which is located in or on a deformation section (5) that can be deformed by the action of a weight force of the measured 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) is formed centrally between two connecting flanges (6, 7) running parallel to each other on the base body (3) of the load cell (1) and serving to establish a detachable connection with the measured object (2), wherein furthermore: -a deformation gap (8, 9) exists between the deformation section (5) and the connection flanges (6, 7), -the base body (3), the deformation section (5) and the connecting flanges (6, 7) each have a through opening (10, 11) in a direction transverse to their longitudinal extent, so that the deformation section (5) can be coupled to a lifting device (12) that causes a change in length, by means of which the measuring object (2) can be transferred from a starting position to a weighing position, -the base body (3), the deformation section (5) and the connecting flanges (6, 7) are formed in one piece and -the load cell (1) has an overall E-shape or comb shape in a side view, characterized by the fact that the deformation section (5) has a ring flange (13) on which, when the lifting device (12) is mounted, a corresponding pressure flange (14) of a pressure sleeve (15) of the lifting device (12) slides, wherein a threaded bolt (17) of the lifting device (12) is screwed into the pressure sleeve (15), the opposite end of which is fixed to the base (16), anchored in the base (16) or supported on the base (16). or the deformation section (5) has an internal thread (18) into which, when the lifting device (12) is mounted, a corresponding threaded bolt (17) is screwed, which is supported on the substrate (16) or anchored in the substrate (16) with its end opposite the thread.

Description

[0001] The invention relates to a load cell 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 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] DE 38 02 153 A1 discloses a load cell for determining the weight of a measurement object. The load cell consists of a base body and at least one measuring element located in or on a deformation section deformable by the action of a weight force of the measurement object. The measuring element generates an electrically measurable output signal corresponding to the deformation. The deformation section is formed centrally between two connecting flanges running parallel to each other on the base body of the load cell and serving to establish a detachable connection with the measurement object. The base body, the deformation section, and the connecting flanges are formed in one piece, so that the load cell, viewed from the side, has an overall E-shape or comb shape.

[0006] A similar solution also emerges from DE 101 00 571 A1.

[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 load cell for determining the weight of a measuring object, which has an overall simple design and thereby reduces the measuring errors and places the lowest possible load on the measuring object.

[0009] The invention solves this problem with the features of patent claim 1.

[0010] A load cell for determining the weight of a measurement object, in which the load cell consists of a base body and at least one measuring element which is present in or on a deformation section which is deformable by the action of a weight force of the measurement object, and in which the measuring element generates an electrically measurable output signal corresponding to the deformation, which can be processed in an evaluation electronics, and in which the deformation section is formed centrally between two connecting flanges which run parallel to one another on the base body of the load cell and serve to establish a detachable connection with the measurement object, wherein a deformation distance exists between the deformation section and the connecting flanges, and the base body, the deformation section and the connecting flanges each have a through-opening in the direction transverse to their longitudinal extent,so that the deformation section can be coupled to a lifting device causing a change in length, by means of which the measuring object can be transferred from an initial position into a weighing position, in which furthermore the base body, the deformation section and the connecting flanges are formed in one piece and the load cell has an E-shape or comb shape in a side view, was further developed according to the invention in such a way that the deformation section has an annular flange, on which a corresponding pressure flange of a pressure sleeve of the lifting device slides when the lifting device is mounted, 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, or the deformation section has an internal thread into which a corresponding threaded bolt is screwed when the lifting device is mounted, which bolt rests on the ground with its end opposite the thread or is anchored in the ground.

[0011] The key advantage of the solution according to the invention is that the load cell consists of only a few individual parts and is therefore extremely simple in design. A particularly preferred embodiment is one in which the base body, the deformation section formed thereon and the connecting flanges likewise formed on the base body, form a one-piece component. The load cell is particularly advantageously attached to the measuring object via the connecting flanges using a detachable connection, allowing the load cell to be replaced if necessary. The deformation section, on the other hand, is connected to the base, so that the weight of the measuring object permanently acts on the deformation section via the connecting flanges.In the simplest case, the connection flanges each consist of a web formed from the base body, into which a bore or thread is introduced on the front side, i.e. on the side facing the measurement object, whereby the detachable connection to the measurement object can preferably be created if a corresponding bolt, pin or rivet is present on the measurement object or is introduced into the measurement object. Equally, however, the connection flanges can also be provided with at least one through-opening, for example transverse to their longitudinal extent, so that this through-opening serves to detachably fix the load cell to the measurement object, for example by a screw, bolt or rivet being passed through this through-opening and connected to the measurement object, or such a bolt, rivet or screw is present in the measurement object onto which the connection flanges can be placed.A further key aspect of the invention is that the base body of the load cell can be attached directly or indirectly to the measurement object, which is particularly advantageously also possible retrospectively, i.e., when the measurement object is already present and / or installed. Furthermore, it was found that by fixing the measurement object to the connection flanges on the measurement object, which are preferably equidistant and parallel to one another in the unloaded state, a very low bending moment is created. This leads to a lower load in the sense of deformation of the measurement object and thus to more accurate 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. The fact that two connection flanges are present in the load cell according to the invention also increases the overall stability and also improves the achievable measurement accuracy. The load cell according to the invention has an E-shape or comb shape when viewed from the side. It can be protected from contamination or weather influences, for example, by simple encapsulation or by attaching or placing a cover, which is particularly useful for outdoor use.A further aspect of the invention is that the connecting flanges each have a through-opening in a direction transverse to their longitudinal extent, such that the deformation section can be coupled through the through-openings to a lifting device which causes a change in length and by means of which the measurement object can be transferred from an initial position to a weighing position. In other words, the measurement object is connected to the load cell via the connecting flanges and the deformation section is used to transfer the measurement object to a defined height position so that the weight of the measurement object acts directly on the deformation section. In this way, the load cell can be attached to the side of a measurement object placed on a base, for example, 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 measuring object, but can also be advantageously arranged to the side of the measuring object, which significantly simplifies installation, i.e., the connection of the load cell to the measuring object. The lifting device can be particularly advantageously 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 measuring 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 introduced 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. Furthermore, the load cell is particularly preferably fastened vertically to the measurement object to be weighed, since this type of fastening makes it particularly easy to connect it to a lifting device. By connecting the load cell to the measurement object in this way, the previously explained advantages of greater measurement accuracy and lower bending moments on the measurement object can be achieved. As already indicated above, a further measure of the invention consists in the deformation section and the connecting flanges running parallel to the deformation section being formed integrally on the base body.The one-piece design of the base body with the deformation section and the connecting flanges makes the load cell very simple in its construction, thus reducing the manufacturing effort for such a load cell. Ultimately, this also has a positive effect on manufacturing costs. Furthermore, the deformation section of a load cell according to the invention has an annular flange against which, when the lifting device is installed, a corresponding pressure flange of a pressure sleeve of the lifting device slides. A threaded bolt of the lifting device is screwed into the pressure sleeve, with its opposite end fixed to the substrate, anchored in the substrate, or supported on the substrate.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] It shows: Fig. 1: a section through a first embodiment of a load cell attached to a measuring object in a weighing position of the measuring object, Fig. 2: a section through a second embodiment of a load cell attached to a measuring object in a weighing position of the measuring object, Fig. 3: a spatial representation of a measuring object with a load cell attached to it and Fig. 4: an alternative way of attaching a load cell to a measuring object.

[0017] The Fig. 1 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. 1 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 in a manner described in more detail below 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. 1, which means that 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 6 and 7 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 6, 7 have on their front sides, i.e. on their side facing the measuring object 2, in the Fig. 1 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 6, 7 and the deformation section 5 present between the connecting flanges 6, 7, the load cell 1 in the present case has a deformation distance 8 and 9, which in the example shown is formed by a slot, so that a relative movement is possible between the deformation section 5 and at least one of the deformation distances 8, 9 due to the weight of the measuring object 2 acting on the deformation section 5. As a result, the previously mentioned measurement signal proportional to the weight of the measuring object 2 is generated in the measuring element 4 and the load cell 1 acquires its characteristic E-shape or comb shape in a side view.

[0018] The assembly of the load cell 1 takes place in the Fig. 1, 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 6, which is perpendicular to the longitudinal extension of the connecting flanges 6, 7, i.e. vertically extending, and through a through-opening 11 in the connecting flange 7, which also runs in the same direction, and has a pressure flange 14 in the region of the deformation section 5 of the load cell 1, 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. 1, 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 12, 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.

[0019] The Fig. Figure 2 illustrates an alternative embodiment 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 connecting flanges 6 and 7, spaced therefrom by a deformation distance 8 and 9 respectively and extending parallel to one another, are formed in one piece. In the connecting flanges 6, 7, which are fixed to the measuring object 2 by means of screw bolts 19 and 20, a through-opening 10, 11 is made each, aligned vertically to the longitudinal extent of the connecting flanges 6, 7, the diameter of which through-opening 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 further has a hexagon nut 27, which in the illustration of Fig. 2 rests with its contact surface on a base 26. The base 26 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 thread in the deformation section 5 and the threaded bolt 17 screwed therein, which leads to a lifting movement of the lifting device 12 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.

[0020] From the Fig. 3 shows a spatial representation of part of the measurement object 2. The load cell 1 is attached laterally to the measurement object 2. The rod- or beam-like connecting flanges 6 and 7 serve to attach the load cell 1 to the measurement object 2. Between the connecting flanges 6 and 7, the deformation section 5 with the measuring element 4 integrated therein is also formed integrally on the base body 3 in the manner already described. Between the connecting flanges 6 and 7 and the deformation section 5 running centrally and parallel to the connecting flanges 6, 7, this load cell 1 also has deformation distances 8 and 9 in the form of continuous slots. The illustration clearly shows how the ground anchor 21 can be attached to the base 16. The previously described screw bolt is passed through the visible hole in the ground anchor 21 and fixed in the base 16.The connection between the ground anchor 21 and the threaded bolt 17 is made via the screw bolt 23.

[0021] Only as an example, the Fig. 4 shows a detail of a load cell 1 according to the invention with an E-shape or comb shape, which in the example shown is attached to the measuring object 2 in a manner different from the previous illustrations. A total of 4 fastening holes 28 are used to fix the load cell 1, through which Fig. 4 screw bolts (not shown for simplification reasons) are passed through and screwed into the measuring object 2. The special feature of the assembly of the Fig. 4 is that it is not attached to the measuring object 2 by the end face of the rod- or beam-like connecting flanges 6 and 7, but by the longitudinal side of the connecting flanges 6 and 7, which are penetrated by the fastening holes 28. The connecting flange 6 has two fastening holes 28 and the connecting flange 7 also has two fastening holes 28. In the illustration of the Fig. For the sake of simplicity, some elements have been omitted in Figure 4 and only the load cell 1 on the measuring object 2 is shown. LIST OF REFERENCE SYMBOLS: 1 load cell 2 Measuring object 3 basic bodies 4 measuring element 5 Deformation section 6 Connection flange 7 Connection flange 8 Deformation distance 9 Deformation distance 10 passage opening 11 Passage opening 12 Lifting device 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 Stand (ball joint) 27 Hexagon nut 28 mounting holes

Claims

[1] Load cell (1) for determining the weight of a measurement object (2), wherein the load cell (1) consists of a base body (3) and at least one measuring element (4) which is present in or on a deformation section (5) 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) is formed centrally between two connecting flanges (6, 7) which run parallel to one another on the base body (3) of the load cell (1) and serve to establish a detachable connection with the measurement object (2), wherein furthermore: -there is a deformation distance (8, 9) between the deformation section (5) and the connecting flanges (6, 7), -the base body (3), the deformation section (5) and the connecting flanges (6, 7) each have a through-opening (10, 11) in the direction transverse to their longitudinal extent, so that the deformation section (5) can be coupled to a lifting device (12) causing a change in length, by means of which the measuring object (2) can be transferred from an initial position to a weighing position, -the base body (3), the deformation section (5) and the connecting flanges (6, 7) are formed in one piece and -the load cell (1) has an overall E-shape or comb shape in a side view, characterized by , 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 (12) slides when the lifting device (12) is mounted, wherein a threaded bolt (17) of the lifting device (12) 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) or the deformation section (5) has an internal thread (18) into which, when the lifting device (12) is mounted, a corresponding threaded bolt (17) is screwed, which is supported with its end opposite the thread on the base (16) or is anchored in the base (16).

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