WEIGHING SENSOR

Abstract

In a weighing sensor for a scale, comprising a base (1), a load receiver (4) jointedly linked to the base (1) by means of a parallelogram linkage, and a lever mechanism having at least two force transmitting levers each having a load arm (14, 23, 28, 35, 39, 46, 54) and an force arm (19, 30, 38), the force transmitting levers (8, 9, 36, 40, 50) being supported by means of supporting joints (17, 24, 29, 37, 42, 48, 55, 60) defining supporting joint pivot points on the base (1), and being arranged one behind the other as seen in the longitudinal direction of the weighing sensor, it is provided that all force transmitting levers (8, 9, 36, 40, 50) are two-sided levers.

Claims

1. A weighing sensor for a scale, comprising: a) a base (1), b) a load receiver (4) jointedly linked to the base (1) by means of a parallelogram linkage, and c) a lever mechanism having at least two force transmitting levers (8, 9, 36, 40, 50) each having a load arm (14, 23, 28, 35, 39, 46, 54) and a force arm (19, 30, 38), the force transmitting levers (8, 9, 36, 40, 50) being aa) supported by means of supporting joints (17, 24, 29, 37, 42, 48, 55, 60) defining supporting joint pivot points on the base (1), and bb) arranged one behind the other as seen in the longitudinal direction of the weighing sensor, characterized in that d) all force transmitting levers (8, 9, 36, 40, 50) are two-sided levers.

2. The weighing sensor according to claim 1, characterized in that the force transmitting levers (8, 9, 36, 40, 50) are formed as straight levers.

3. The weighing sensor according to claim 1, characterized in that the force transmitting levers (8, 9, 36, 40, 50) are aligned essentially parallel to each other.

4. The weighing sensor according to claim 3, characterized in that the force transmitting levers (8, 9, 36, 40, 50) are aligned perpendicular to the direction of a load (L) applied to the load receiver (4).

5. The weighing sensor according to claim 1, characterized in that the lever mechanism has at least an additional third force transmitting lever(10, 47).

6. The weighing sensor according to claim 5, characterized in that the third force transmitting lever (10, 47) acts as a straight lever, has its lever orientation essentially parallel to the first two force transmitting levers (8, 9, 36, 40, 50), and the three force transmitting levers (8, 9, 10, 36, 40, 47, 50) are arranged one behind the other in the longitudinal direction of the weighing sensor.

7. The weighing sensor according to claim 1, characterized in that, on the load arm (14, 23, 28, 35, 39, 46, 54) of at least one of the force transmitting levers (8, 9, 10, 36, 40, 47, 50), a load joint (16, 22, 27, 34, 45, 53) is arranged having a load transmitting function when it receives a load having a load joint pivot point, and the load joint pivot point is in a common supporting plane with a supporting joint pivot point of the supporting joint (17, 24, 29, 37, 42, 48, 55) of the associated force transmitting lever (8, 9, 10, 36, 40, 47), wherein the supporting plane is essentially parallel to the link plane of a parallelogram link (2, 3) of the non-loaded parallelogram linkage.

8. The weighing sensor according to claim 1, characterized in that at least one coupling element (13, 21, 26, 33, 51) is arranged between the load receiver (4) and the first force transmitting lever (8) and/or between force transmitting levers (8, 9, 10, 36, 40, 47, 50) adjacent to each other.

9. The weighing sensor according to claim 8, characterized in that one coupling element (13, 21, 26, 33, 51) is arranged between each of said load receiver (4) and the first force transmitting lever (8) and between all said force transmitting levers (8, 9, 10, 36, 40, 47, 50) adjacent to each other.

10. The weighing sensor according to claim 8, characterized in that all coupling elements (13, 21, 26, 33, 51) are aligned parallel to each other.

11. The weighing sensor according to claim 8, characterized in that the coupling elements are arranged parallel to a direction of a force (L) acting on the load receiver (4).

12. The weighing sensor according to claim 8, characterized in that each connection from each coupling element (13, 21, 26, 33, 51) to the load receiver (4) or to the force transmitting lever (8, 9, 10, 36, 40, 47, 50) is via a coupling element joint (15, 16, 20, 22, 25, 32, 34, 41, 43, 45, 52, 53).

13. The weighing sensor according to claim 8, characterized by at least one pair of coupling elements (21a, 21b) arranged parallel to each other, arranged adjacent to each other and connected to the same arm, load arm (14, 23, 28, 35, 39, 46, 54) or force arm (19, 30, 38) of one of the force transmitting levers (8, 9, 10, 36, 40, 47, 50), wherein the arm protrudes into the coupling element space left between the two coupling elements (21a, 21b) of the pair.

14. The weighing sensor according to claim 8, characterized in that the lever mechanism is designed such that as the load receiver (4) is loaded in a preferred loading direction each coupling element (13, 21, 26, 33, 51) is loaded on tension.

15. The weighing sensor according to claim 8, characterized in that the lever mechanism is designed such that as a load is received each coupling element (13, 21, 26, 33, 51) transmits the force in a direction parallel to the loading direction.

16. The weighing sensor according to claim 1, characterized in that at least the load receiver (4), the base (1), the parallelogram linkage and the force transmitting levers (8, 9, 10, 36, 40, 47, 50) are integrally formed with the exception of an optional extension of the force arm (30) provided for engagement with a force compensation means.

17. The weighing sensor according to claim 1, characterized in that the load receiver (4), the base (1), the parallelogram linkage and the force transmitting levers (8, 9, 10, 36, 40, 47, 50) are symmetrical with respect to a central plane defined by the longitudinal direction of the weighing sensor and a tangent on the pivoting movement of the parallelogram linkage when the load receivers are loaded.

18. The weighing sensor according to claim 1, characterized in that a lever extension is arranged on the force arm (19, 30, 38) of the force transmitting lever (10, 40) most remote from the load receiver (4).

19. The weighing sensor according to claim 1, characterized in that a parallelogram link of the parallelogram linkage (2, 3) and/or linkage joints (5) and/or the base (1) has a tool access opening (49) allowing tool access to at least a part of the lever mechanism.

Description

[0037] A preferred exemplary embodiment of the weighing sensor according to the invention will be schematically shown with reference to two figures, wherein:

[0038] FIG. 1 shows the embodiment of the weighing sensor in a side view;

[0039] FIG. 2 shows the weighing sensor according to FIG. 1 in an oblique perspective view;

[0040] FIG. 2a shows a detailed view of the weighing sensor according to FIG. 1 in the area of the coupling-element pair;

[0041] FIG. 3 shows the lever mechanism of a second embodiment of the invention;

[0042] FIG. 4 shows the lever mechanism of a third embodiment according to the invention; and

[0043] FIG. 5 shows the lever mechanism of a fourth embodiment according to the invention.

[0044] The weighing sensor in the embodiment according to FIGS. 1 and 2 has a symmetrical structure with respect to a mirror plane defined by the X axis and the Z axis, centrally extending in the longitudinal direction of the weighing sensor. The areas that are crosshatched in the figures represent section edges to enable viewing of the interior.

[0045] The weighing sensor has a base 1 comprising a fixed part referred to as a base body 61, which in use is fixed to a base unit (not shown) of a weighing machine. The base body 61 is connected to a load receiver 4 via a top parallelogram link 2 and a bottom parallelogram link 3. The parallelogram links 2 and 3 are connected to the base body 61 via first link joints 5 and to the load receiver 4 via second link joints 6. The link joints 5 and 6 preferably formed as solid body joints enable the load receiver 4 to be displaced with respect to the base body 1. Holding elements 7 protruding in the manner of a cantilever are provided on the load receiver 4, which can serve for fixing, such as by means of screw connections, of further elements (not shown), for example a weighing platform. The holding elements 7 protruding in the manner of a cantilever are not indispensable, since a weighing platform or any other element can also be directly screwed onto an accessible side of the load receiver.

[0046] The lever mechanism consisting of three force transmitting levers 8, 9 and 10 is arranged between the load receiver 4 and the base body 61, wherein the force transmitting levers 8, 9 and 10 are formed as straight levers. The force transmitting levers 8, 9 and 10 are essentially parallel to each other and perpendicular to the direction of an effective load L. The lever mechanism thus comprises a first force transmitting lever 8, a second force transmitting lever 9 and a third force transmitting lever 10, wherein the third force transmitting lever 10 protrudes into an open interior space 12 of the base body 61 through a cutout 11. Alternatively, the third force transmitting lever 10 can extend completely through the base body 61 through a cutout. The third force transmitting lever 10 can be provided for mounting a force compensating component, such as a magnet, or a force receiving element, such as a string. In the case of a force-receiving string, the third force transmitting lever 10 pulls on the string which, in turn, increases the resonant frequency and thus, by means of a frequency exciter, allows conclusions to be drawn on the weight applied over a certain time unit by applying computational methods.

[0047] The third force transmitting lever 10 according to FIGS. 1 and 2 symmetrically extends on the base 1 and also forms a monolithic structure with the base 1. Alternatively, the third force transmitting lever 10 can extend asymmetrically or even laterally along the base. The third force transmitting lever 10 can also be screwed on.

[0048] In a structure having less or more than three force transmitting levers, what is discussed with respect to the third force transmitting lever 10 then also applies to the force transmitting lever within the lever mechanism leading up to the force compensation means.

[0049] The following is a presentation of the further structure with reference to an exemplary functioning principle of the weighing sensor. When the load receiver 4 is loaded with a load L, the load receiver 4 has a force applied to it relative to the base 1. The applied force results in minimal displacement due to the lever mechanism, which is immediately compensated, however, by means of force compensation, such as by means of coils and magnets, thus restoring the same position to the system and thus to the load receiver.

[0050] The force of the applied load L is transmitted to a load arm 14 of the first force transmitting lever 8 via a coupling element 13. The coupling element 13 is jointedly linked to the load receiver 4 via a load-receiver coupling joint 15 (only visible in FIG. 1). A load joint 16 is provided between the coupling element 13 and the load arm 14. The first force transmitting lever 8, via a first supporting joint 17, is supported on a base cantilever 18 extending from the base body 61 towards the load receiver 4. The pivot point of the first supporting joint 17 and the pivot point of the first load joint 16 lie in a common horizontal plane.

[0051] A force arm 19 of the first force transmitting lever 8 is split in a fork-like manner into two separate partial force arms 19a and 19b (only visible in the detailed view of FIG. 2A) each of which is connected to a further coupling element 21a and 21b (only visible in FIG. 2A) via an force-arm coupling joint 20a and 20b, respectively (also only visible in FIG. 2A), wherein each further coupling element 21a and 21b, in turn, is connected to a load arm 23 of the second force transmitting lever 9 via a load joint 22 (of which the figures only show one). The coupling elements 21a and 21b thus form a coupling-element pair which extends on both sides of the load arm 23.

[0052] The second force transmitting lever 9 is supported on the base cantilever 18 via a second supporting joint 24 and is connected to a further coupling element 26 via a further force-arm coupling joint 25. The coupling element 26 is finally connected to a load arm 28 of the third force transmitting lever 10 via a load joint 27, the force transmitting lever 10, in turn, being supported on the base cantilever 18 via a third supporting joint 29. The force arm 30 protruding into the interior 12 of the base body 61 extends up to a force compensation means (not shown) which cooperates with the force arm 30 in a well-known manner.

[0053] All coupling elements 13, 21, 26 are parallel to each other and parallel to a force L acting on the load receiver 4.

[0054] The top parallelogram link 2 includes a tool access opening 49 which can serve to finalize the coupling elements 21a and 21b, since they have to be separated from the load arm 23 up to the joint 22 by means of an undercut. A further tool access opening (not shown in the drawings) can be present in the region of the cutout 11 vertically from the top, for example to mount a lever extension (not shown) on the force arm 30 of the third force transmitting lever 10.

[0055] FIGS. 3 to 5 show alternative embodiments of the lever mechanism, wherein, to simplify the drawing, the surrounding base 1 and the base cantilevers 18 (see FIGS. 1 and 2) are only schematically shown with support points (SG1-SG3).

[0056] In the embodiment according to FIG. 3, a cantilever 31 of the load receiver (not shown) is connected to a coupling element 33 via a load-receiver coupling joint 32, the coupling element 33, in turn, being connected to the load arm 35 of a first force transmitting lever 36 via a load joint 34. The first force transmitting lever 36 is supported on the base cantilever via a first supporting joint 37. An force arm 38 of the first force transmitting lever 36 is split in a fork-like manner, which is not visible in the figure, at its leading end into two force arm portions, similar to the split of the force arm 19 in FIG. 1, and receives a portion of the load arm 39 of the second force transmitting lever 40 between the partial force arms. The force arm 38 of the first force transmitting lever 36 and the load arm 39 of the second force transmitting lever 40 are connected to each other via a pair of force-arm coupling joints 41, of which only the leading one is shown in perspective.

[0057] The second force transmitting lever 40 is supported on the base cantilever via the second supporting joint 42.

[0058] The second force transmitting lever 40, also formed as a straight two-sided lever and essentially oriented parallel to the other force transmitting levers 36, 47, is connected to the load arm 46 of the third force transmitting lever 47 via a further force-arm coupling joint 43, a further coupling element 44 parallel in orientation both to the coupling element 33 and to the direction of the application of force L, and a load joint 45, the third force transmitting lever 47 being supported on the base cantilever 18 via the third supporting joint 48. The lever mechanism according to FIG. 3 is different from the embodiment according to FIGS. 1, 2 and 2a with respect to the type of coupling between the first force transmitting lever 36 oriented perpendicular to the direction of the application of and the second force transmitting lever 40 oriented perpendicular to the direction of the applied load L. At this point, a coupling element has been dispensed with, so that only one joint, namely the force-arm coupling joint 41, is provided between the first force transmitting lever 36 and the second force transmitting lever 40. The pivot point of the supporting joint 42 and the pivot point in the force-arm coupling joint 41 are thus not decoupled. This can lead to measuring errors, which can be negligible, however, for certain applications, in particular for dynamic weighing.

[0059] At this point, it should be noted that a base cantilever of the type shown does not necessarily have to be present. Alternatively, it is possible for the base to be arranged completely below the lever mechanism and, as the case may be, for a force compensation means to be mounted on the base by means of additional elements.

[0060] FIG. 4 describes a further embodiment, wherein elements used in a corresponding manner to the embodiment according to FIG. 3 are indicated with the same reference numerals. With respect to the description, reference is made, in particular, to the explanations relating to FIG. 3. In contrast to the embodiment according to FIG. 3, the second force transmitting lever 50, also oriented parallel to the force transmitting levers 36, 46 and perpendicular to the applied load L, is connected to the force arm 38 of the first force transmitting lever via a coupling element 51 in turn oriented parallel to the other coupling elements 33, 44 and parallel to the direction of the applied load L. The coupling element 51 has a force-arm coupling joint 52 for connection to the force arm 38 of the first force transmitting lever 36 and a load joint 53 for connection to the load arm 54 of the second force transmitting lever. The second force transmitting lever 50 is supported on the base cantilever via the second supporting joint 55, wherein, in contrast to the other embodiments, a portion of the base cantilever has to be above the second force transmitting lever 55. While this achieves decoupling of the pivot points on the second force transmitting lever, the reversed orientation of the second supporting joint 55 makes the arrangement of the lever mechanism in the base cantilever substantially more complex. In comparison to the embodiment according to FIG. 1, a greater structural height in the lever mechanism is also necessary.

[0061] Finally, FIG. 5 shows a further embodiment largely similar to the embodiment according to FIG. 4. Due to the corresponding elements, reference is made to the description of FIGS. 3 and 4. The difference between the embodiment of FIG. 5 and the embodiment according to FIG. 4 lies only in the second force transmitting lever 50, again formed as a straight lever parallel to the other force transmitting levers 36, 46 and perpendicular to the applied load L, being supported at its bottom side by means of the supporting joint 60. In comparison to FIG. 4, this makes the linkage of the lever mechanism less complex in the base cantilever. A drawback is, however, that the pivot points of the load joint 53 and the second supporting joint 60 are not arranged in a common plane oriented perpendicular to the direction of gravity. This can lead to measuring errors. Moreover, the structural height of the lever mechanism is higher.

LIST OF REFERENCE NUMERALS

[0062] 1 base [0063] 2 top parallelogram link [0064] 3 bottom parallelogram link [0065] 4 load receiver [0066] 5 first link joints [0067] 6 second link joints [0068] 7 holding element [0069] 8 first force transmitting lever [0070] 9 second force transmitting lever [0071] 10 third force transmitting lever [0072] 11 cutout [0073] 12 interior of base [0074] 13 coupling element [0075] 14 load arm [0076] 15 load-receiver coupling joint [0077] 16 load joint [0078] 17 first supporting joint [0079] 18 base cantilever [0080] 19 force arm [0081] 19a partial force arm [0082] 19b partial force arm [0083] 20a force-arm coupling joint [0084] 20b force-arm coupling joint [0085] 21a second coupling element [0086] 21b third coupling element [0087] 22 load joint [0088] 23 load arm [0089] 24 second supporting joint [0090] 25 force-arm coupling joint [0091] 26 coupling element [0092] 27 load joint [0093] 28 load arm [0094] 29 third supporting joint [0095] 30 force arm [0096] 31 cantilever load receiver [0097] 32 load-receiver coupling joint [0098] 33 coupling element [0099] 34 load joint [0100] 35 load arm [0101] 36 first force transmitting lever [0102] 37 first supporting joint [0103] 38 force arm [0104] 39 load arm [0105] 40 second force transmitting lever [0106] 41 force-arm coupling joint [0107] 42 second supporting joint [0108] 43 force-arm coupling joint [0109] 44 coupling element [0110] 45 load joint [0111] 46 load arm [0112] 47 third force transmitting lever [0113] 48 third supporting joint [0114] 49 tool access opening [0115] 50 second force transmitting lever [0116] 51 coupling element [0117] 52 force-arm coupling joint [0118] 53 load joint [0119] 54 load arm [0120] 55 second supporting joint [0121] 60 second supporting joint [0122] 61 base body