Metrology

Abstract

The present invention provides a weighing mechanism that allows for the separation of a first strain-generating body for weighing the object to be weighed and a second strain-generating body for calibration. [Solution] The weighing mechanism 1 includes a first strain body 2 that receives a first load which is the load of the object to be weighed, a second strain body 4 that receives a second load which is the load of a calibration weight W, and a load sensor 8 that detects the first load transmitted from the first strain body 2 and the second load transmitted from the second strain body 4. The load sensor 8 is attached to the first strain body 2, and the second strain body 4 is detachably attached to the first strain body 2.

Description

Technical Field

[0004] , , , , , , , , , ,

[0003] , , ,<00000​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​In the load measurement mechanism described above, the force sensor is fixed to the second force conversion unit, and the load of the object to be measured is transmitted to the force sensor via the load receiving unit of the Roberval unit, the first force conversion unit, and the force receiving unit of the second force conversion unit which has a Roberval mechanism. Furthermore, a weight placement unit is fixed to the force receiving unit of the second force conversion unit, and the load of the reference weight placed on the weight placement unit during calibration of the force sensor is applied to the force receiving unit of the second force conversion unit and transmitted to the force sensor. Thus, in the load measurement mechanism described above, the second force conversion unit is used in conjunction with the measurement of the object to be measured and the calibration using the reference weight to transmit the load to the force sensor. Therefore, in the load measurement mechanism described above, it is difficult to use the first force conversion unit and the second force conversion unit separately.

[0005] Therefore, the present disclosure aims to provide a weighing mechanism in which a first strain-generating body for weighing the object to be weighed and a second strain-generating body for calibration can be separated. [Means for solving the problem]

[0006] The weighing mechanism relating to this disclosure is a weighing mechanism comprising: [1] a first strain body that receives a first load which is the load of an object to be weighed; a second strain body that receives a second load which is the load of a calibration weight; and a load sensor that detects the first load transmitted from the first strain body and the second load transmitted from the second strain body, wherein the load sensor is attached to the first strain body and the second strain body is detachably attached to the first strain body.

[0007] In this weighing mechanism, a load sensor for detecting a first load, which is the load of the object being weighed, and a second load, which is the load of a calibration weight, is attached to a first strain body that receives the first load of the object being weighed, and a second strain body that receives the second load of the calibration weight is detachably attached to the first strain body. Therefore, the second strain body can be removed from the first strain body, and even when the second strain body is removed, the object being weighed can be weighed using the first strain body and the load sensor. Thus, in this weighing mechanism, the first strain body for weighing the object being weighed and the second strain body for calibration can be separated. Furthermore, since the first strain body and the second strain body can be separated in this weighing mechanism, it is possible to ship the device with the second strain body removed to users who do not require calibration of the load sensor using the second strain body, thereby reducing costs.

[0008] The measuring mechanism relating to this fire may also be a measuring mechanism comprising: [2] "the first strain body comprising a measuring lever mechanism having a first lever ratio and a transmission unit connected to the load sensor, which transmits the first load converted by the measuring lever mechanism according to the first lever ratio to the load sensor via the transmission unit; the second strain body comprising a calibration lever mechanism having a second lever ratio different from the first lever ratio and a fixed unit fixed to the transmission unit, which transmits the second load converted by the calibration lever mechanism according to the second lever ratio to the load sensor via the fixed unit and the transmission unit; and a flexible flexure unit extending in a direction intersecting the direction in which the fulcrum and the point of application of the calibration lever mechanism are aligned, between the fulcrum of the calibration lever mechanism and the fixed unit." In this case, a second strain body having a lever mechanism is connected to a transmission part of a first strain body having another lever mechanism, allowing the first load from the first strain body and the second load from the second strain body to be easily transmitted to the load sensor via the transmission part. On the other hand, in such a structure, if the radii of rotation around the fulcrums of the lever mechanisms of the first and second strain bodies are different, the fixed parts of the two bodies may become stiff, potentially hindering the operation of the lever mechanisms. In contrast, this weighing mechanism has a flexible flex section between the fulcrum and the fixed part of the lever mechanism of the second strain body. Therefore, the bending of the flex section suppresses the inhibition of the lever mechanism's operation due to stiffness at the fixed part. In particular, since the flex section extends in a direction that intersects the direction in which the fulcrum and the point of application of the lever mechanism of the second strain body are aligned, the influence of the flex section on the lever ratio of the lever mechanism of the second strain body is suppressed.

[0009] The weighing mechanism relating to this disclosure may also be [3] "the weighing mechanism according to [2] above, wherein the calibration lever mechanism has a second lever ratio for increasing the second load, and the load sensor detects the second load transmitted from the second strain body by the calibration lever mechanism." In this case, the second strain body has a calibration lever mechanism for increasing the load of the weight, and the load sensor detects the load of the weight transmitted from the second strain body by the calibration lever mechanism. As a result, the load of the weight can be increased and transmitted to the load sensor, so even if a load sensor capable of detecting a large load is used to improve impact resistance, a relatively light weight can be used to apply a large load to the load sensor, and the load sensor can be calibrated accurately. Therefore, in this case, it is possible to improve impact resistance while ensuring calibration accuracy.

[0010] The weighing mechanism relating to this disclosure may also be [4] "the weighing mechanism according to [2] or [3] above, wherein the weighing lever mechanism has a first lever ratio for reducing the first load, and the load sensor detects the first load that has been reduced and transmitted from the first strain body by the weighing lever mechanism." In this way, when a lever mechanism (weighing lever mechanism) is used for the first strain body, the larger the reduction rate of the load in the first strain body (the reciprocal of the lever ratio of the weighing lever mechanism), the larger the change in the lever ratio when the lever mechanism is displaced by an external impact. As a result, external impacts may affect the weighing of the object to be weighed. In contrast, in this weighing mechanism, as described above, when the load of the weight is increased and transmitted to the load sensor, a load sensor capable of detecting a large load can be used, making it possible to maintain a small reduction rate of the lever mechanism in the first strain body. Therefore, this weighing mechanism makes it possible to further improve impact resistance.

[0011] The weighing mechanism relating to this disclosure may also be [5] "the weighing mechanism according to any one of [1] to [4] above, wherein the first strain body includes a first surface and a second surface opposite to the first surface, the second strain body is attached to the first surface, and the load sensor is attached to the second surface." By providing the load sensor on one side of the first strain body and the second strain body on the other side of the first strain body, access to both the load sensor and the second strain body becomes easier.

[0012] The weighing mechanism relating to this disclosure may also be [6] "a weighing mechanism according to any one of [1] to [5] above, which is provided on the side of the second strain body opposite to the side facing the first strain body and includes a weight-holding portion on which the weight is placed." Thus, a weight-holding portion on which a calibration weight is placed may be provided on the side of the second strain body opposite to the first strain body. [Effects of the Invention]

[0013] According to this disclosure, a weighing mechanism can be provided in which a first strain body for weighing the object to be weighed and a second strain body for calibration can be separated. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a perspective view of a weighing mechanism according to one embodiment. [Figure 2] Figure 2 is an exploded perspective view of the weighing mechanism shown in Figure 1. [Figure 3] Figure 3 is a plan view of the first strain body shown in Figure 1. [Figure 4] Figure 4 is a plan view of the second strain body shown in Figure 1. [Figure 5] Figure 5 is a schematic diagram showing the lever mechanism for weighing and the lever mechanism for calibration. [Figure 6] Figures 6(a) and 6(b) schematically illustrate the flow of load transmission in a weighing mechanism. [Modes for carrying out the invention]

[0015] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used for the same or equivalent elements, and redundant explanations will be omitted. Furthermore, in the drawings, some parts are exaggerated in order to clearly illustrate the characteristic parts of the embodiment. For this reason, the dimensional ratios of each part in the drawings may differ from the actual dimensional ratios.

[0016] Figure 1 is a perspective view of a weighing mechanism according to one embodiment. Figure 2 is an exploded perspective view of the weighing mechanism shown in Figure 1. As shown in Figures 1 and 2, the weighing mechanism 1 comprises a first strain body 2, a second strain body 4, a weight placement section 6, a weight moving mechanism 7, a load sensor 8, and a calculation section 9. The second strain body 4 and the load sensor 8 are attached to the first strain body 2. More specifically, the first strain body 2 includes a first surface 2s and a second surface 2r opposite to the first surface 2s, the second strain body 4 is attached to the first surface 2s, and the load sensor 8 is attached to the second surface 2r. In particular, the second strain body 4 is detachably attached to the first strain body 2.

[0017] Specifically, the second strain body 4 is fixed to the first strain body 2 by two bolts 11 and 12. Furthermore, the load sensor 8 is fixed to the first strain body 2 by bolts 13 and 14 (i.e., the load sensor 8 is also detachable). The weight moving mechanism 7 is configured to grip and move the calibration weight W of the weighing mechanism 1. The weight moving mechanism 7 places the weight W on the weight placement section 6 when the weighing mechanism 1 is calibrated. The weight W is a built-in weight of the weighing mechanism 1. The weight placement section 6 is provided on the side of the second strain body 4 opposite to the side facing the first strain body 2. The weighing mechanism 1 is, for example, built into a scale device having a weighing pan and weighs the mass of an object placed on the weighing pan.

[0018] Each of the first deflecting body 2 and the second deflecting body 4 has an outer shape of a substantially rectangular parallelepiped (rectangular block shape) that is long in a predetermined direction. Each of the first deflecting body 2 and the second deflecting body 4 has a so-called Roberval mechanism.Each of the first deflecting body 2 and the second deflecting body 4 is an elastic body formed of a metal such as an aluminum alloy or stainless steel, and is manufactured by hollowing out a metal block.In the following description, the above-mentioned predetermined direction is referred to as the Y-axis direction, a direction perpendicular to the Y-axis direction is referred to as the X-axis direction, and a direction perpendicular to both the Y-axis direction and the X-axis direction is referred to as the Z-axis direction (vertical direction). Each of the X-axis direction and the Y-axis direction is a direction parallel to the horizontal direction.

[0019] Referring further to FIG. 3, details of the first deflecting body 2 will be described. FIG. 3 is a plan view of the first deflecting body shown in FIG. 1. The first deflecting body 2 is a member that receives a first load that is the load of the object to be measured. The first deflecting body 2 includes a load receiving portion (21), a base portion (22), an upper link member (23), a lower link member (24), flexure portions (25, 26, 27, 28), and a fixing portion (29).

[0020] The load receiving portion 21 is a portion that receives the first load from the weighing pan of the weighing device. The load receiving portion 21 corresponds to one end portion in the Y-axis direction of the first deflecting body 2 (the left side in FIG. 3). The weighing pan of the weighing device is connected to the upper surface 21a of the load receiving portion 21. The base portion 22 is a portion that is fixed to, for example, the housing of the weighing device or the like. The base portion 22 corresponds to the other end portion in the Y-axis direction of the first deflecting body 2 (the right side in FIG. 3). For example, the load receiving portion 21 is a free end that is not fixed to the housing of the weighing device or the like, whereas the base portion 22 is a fixed end that is fixed to the housing of the weighing device or the like.

[0021] The upper link member 23 is a portion that connects the load receiving portion 21 and the base portion 22 on one side in the Z-axis direction (the upper side in FIG. 3). The lower link member 24 is a portion that connects the load receiving portion 2 and the base portion that on the other side in the Z-axis direction (the lower side in FIG. 3). The upper link member 23 and the lower link member 24 extend along the Y-axis direction in parallel with each other. The first deflecting body 2 has a Roberval mechanism configured by the load receiving portion 21, the base portion 22, the upper link member 23, and the lower link member 24.

[0022] Each of the flexure sections 25-28 is thinner than the other parts. Each of the flexure sections 25-28 is thinner than the other parts because curved recesses are provided on both the upper and lower sides.

[0023] The flexure portion 25 connects the load-receiving portion 21 to one end of the upper link member 23 in the Y-axis direction (the load-receiving portion 21 side). The flexure portion 25 has a through hole 25a that penetrates the flexure portion 25 along the Z-axis direction. The flexure portion 26 connects the base portion 22 to the other end of the upper link member 23 in the Y-axis direction (the base portion 22 side). The flexure portion 26 has a through hole 26a that penetrates the flexure portion 26 along the Z-axis direction.

[0024] The flexure portion 27 connects the load-receiving portion 21 to one end of the lower link member 24 in the Y-axis direction (the side with the load-receiving portion 21). The flexure portion 28 connects the base portion 22 to the other end of the lower link member 24 in the Y-axis direction (the side with the base portion 22). Each of the flexure portions 27 and 28 has a through hole (not shown) that passes through them along the Z-axis direction, similar to the flexure portions 25 and 26.

[0025] The fixing portion 29 is the part to which the second strain body 4 and the load sensor 8 are fixed. The fixing portion 29 is connected to the base portion 22 and extends along the Y-axis toward the load receiving portion 21. The fixing portion 29 is positioned between the upper link member 23 and the lower link member 24 in the Z-axis direction. The fixing portion 29 has two screw holes 29a that extend along the X-axis direction and open on one side in the X-axis direction (the front side of the paper in Figure 3, the first surface 2s). Two bolts 11 are screwed into the two screw holes 29a from one side in the X-axis direction to fix the second strain body 4 to the first strain body 2. The fixing portion 29 also has a screw hole (not shown) that extends along the X-axis direction and opens on the other side in the X-axis direction (the back side of the paper in Figure 3, the second surface 2r). A bolt 13 is screwed into the screw hole to fix the load sensor 8 to the first strain body 2 from the other side in the X-axis direction.

[0026] The first strain body 2 further includes a weighing lever mechanism 30. The weighing lever mechanism 30 has a first lever ratio and is a mechanism that changes the first load according to the first lever ratio. Here, the first lever ratio is a lever ratio that reduces the first load (i.e., less than 1). Therefore, the weighing lever mechanism 30 is a mechanism that reduces the first load. The weighing lever mechanism 30 has a main body portion 31 and thin-walled portions 32, 33. When viewed from the X-axis direction, the weighing lever mechanism 30 is located inside the Roberval mechanism of the first strain body 2, which is composed of a load receiving portion 21, a base portion 22, an upper link member 23, and a lower link member 24.

[0027] The main body portion 31 is a rod-shaped part extending along the Y-axis direction. The main body portion 31 is positioned between the upper link member 23 and the fixing portion 29 in the Z-axis direction, and between the load receiving portion 21 and the base portion 22 in the Y-axis direction. The main body portion 31 has an end portion 31a positioned on one side (the load receiving portion 21 side) in the Y-axis direction, and an end portion 31b (transmission portion) positioned on the other side (the base portion 22 side) in the Y-axis direction. The end portion 31b has a screw hole 31c that extends along the X-axis direction and opens on one side in the X-axis direction (the front side of the paper in Figure 3, the first surface 2s). A bolt 12 for fixing the second strain body 4 to the first strain body 2 is screwed into the screw hole 31c from one side in the X-axis direction. The end portion 31b has a screw hole (not shown) that extends along the X-axis direction and opens on the other side in the X-axis direction (the back side of the paper in Figure 3, the second surface 2r). A bolt 14 is screwed into the screw hole to fix the load sensor 8 to the first strain body 2 from the other side in the X-axis direction.

[0028] Each of the thin-walled sections 32 and 33 is a part that is thinner than the rest of the structure. The thin-walled section 32 connects the load-receiving section 21 to the end 31a of the main body section 31. The thin-walled section 32 extends along the Z-axis direction from the end 31a toward the lower link member 24. The thin-walled section 33 connects the fixing section 29 to a portion 31d of the main body section 31 located between the end 31a and the end 31b. The portion 31d is located on the end 31a side. The thin-walled section 33 extends along the Z-axis direction from the portion 31d toward the fixing section 29.

[0029] In the weighing lever mechanism 30, the thin-walled section 32 constitutes the point of force application P1, the thin-walled section 33 constitutes the fulcrum P2, and the end section 31b constitutes the point of application P3. Figure 3 schematically shows the positions of the point of force application P1, the fulcrum P2, and the point of application P3. In the first strain-generating body 2, when the load-receiving section 21 receives the first load, the load-receiving section 21, together with the base section 22, the upper link member 23, and the lower link member 24, displaces downward while maintaining a parallelogram shape. Consequently, the end section 31a and the thin-walled section 32 are pulled downward, and the first load is transmitted to the point of force application P1. Then, the end section 31b (point of application P3) displaces upward with the thin-walled section 33 (fulcrum P2) as the fulcrum. Let L1 be the distance between the point of force application P1 and the fulcrum P2 in the Y-axis direction, L2 be the distance between the fulcrum P2 and the point of application P3 in the Y-axis direction, W1 be the first load transmitted to the point of force application P1, and W11 be the first load transmitted to the point of application P3. Then the relationship "W1 × L1 = W11 × L2" is satisfied. Here, since part 31d is located on the end 31a side, the relationship "L2 > L1" is satisfied. As a result, the first load transmitted to the point of force application P1 is reduced according to the lever ratio L1 / L2 and transmitted to the point of application P3.

[0030] The details of the second strain-generating body 4 will be further explained with reference to Figure 4. Figure 4 is a plan view of the second strain-generating body shown in Figure 1. The second strain-generating body 4 is a member that receives the second load, which is the load of the calibration weight. The second strain-generating body 4 has a load-receiving portion 41, a base portion 42, an upper link member 43, a lower link member 44, flexure portions 45, 46, 47, 48, and a fixing portion 49.

[0031] The load-receiving portion 41 is the part that receives the second load from the weight-holding portion 6. The weight-holding portion 6 is fixed to the load-receiving portion 41. The load-receiving portion 41 corresponds to one end of the second strain-generating body 4 in the Y-axis direction (left side in Figure 4). The load-receiving portion 41 has two screw holes 41a that extend along the X-axis direction and open to one side in the X-axis direction (the foreground side in Figure 4). Two bolts 15 are screwed into the two screw holes 41a from one side in the X-axis direction to fix the weight-holding portion 6 to the second strain-generating body 4 (load-receiving portion 41). The base portion 42 corresponds to the other end of the second strain-generating body 4 in the Y-axis direction (right side in Figure 4).

[0032] The upper link member 43 is the part that connects the load-receiving portion 41 and the base portion 42 on one side in the Z-axis direction (upper side in Figure 4). The lower link member 44 is the part that connects the load-receiving portion 41 and the base portion 42 on the other side in the Z-axis direction (lower side in Figure 4). The upper link member 43 and the lower link member 44 extend parallel to each other along the Y-axis direction. The second strain-generating body 4 has a Roberval mechanism composed of the load-receiving portion 41, the base portion 42, the upper link member 43, and the lower link member 44.

[0033] Each of the flexure sections 45-48 is thinner than the other parts. Each of the flexure sections 45-48 is thinner than the other parts because curved recesses are provided on both the upper and lower sides.

[0034] The flexure portion 45 connects the load-receiving portion 41 to one end of the upper link member 43 in the Y-axis direction (the side with the load-receiving portion 41). The flexure portion 46 connects the base portion 42 to the other end of the upper link member 43 in the Y-axis direction (the side with the base portion 42). The flexure portion 47 connects the load-receiving portion 41 to one end of the lower link member 44 in the Y-axis direction (the side with the load-receiving portion 41). The flexure portion 48 connects the base portion 42 to the other end of the lower link member 44 in the Y-axis direction (the side with the base portion 42).

[0035] The fixing portion 49 is the part of the first strain body 2 that is fixed to the fixing portion 29. The fixing portion 49 is connected to the base portion 42 and extends along the Y-axis toward the load receiving portion 41. The fixing portion 49 is positioned between the upper link member 43 and the lower link member 44 in the Z-axis direction. The fixing portion 49 has two through holes 49a that extend along the X-axis direction. Bolts 11 are inserted through the through holes 49a.

[0036] The second strain body 4 further includes a calibration lever mechanism 50, a connecting portion 61, a thin-walled portion 62, and a fixing portion 63. The calibration lever mechanism 50 has a second lever ratio different from the first lever ratio and is a mechanism that converts the second load according to the second lever ratio. Here, the second lever ratio is a lever ratio that increases the second load (i.e., is greater than 1). Therefore, the calibration lever mechanism 50 is a mechanism that increases the second load. The calibration lever mechanism 50 has a main body portion 51, thin-walled portions 52, 53, and a flexure portion 54. When viewed from the X-axis direction, the calibration lever mechanism 50 is located inside the Roberval mechanism of the second strain body 4, which is composed of a load receiving portion 41, a base portion 42, an upper link member 43, and a lower link member 44.

[0037] The main body portion 51 is a rod-shaped part that extends along the Y-axis direction. The main body portion 51 is positioned between the upper link member 43 and the fixing portion 49 in the Z-axis direction, and between the load-receiving portion 41 and the base portion 42 in the Y-axis direction. The main body portion 51 has an end portion 51a positioned on one side (the load-receiving portion 41 side) in the Y-axis direction, and an end portion 51b positioned on the other side (the base portion 42 side) in the Y-axis direction.

[0038] Each of the thin-walled sections 52, 53 and the flexure section 54 is a part that is thinner than the rest of the structure. The thin-walled section 52 connects the load-receiving section 41 to the end 51a of the main body section 51. Specifically, the thin-walled section 52 is connected to the load-receiving section 41 via the connecting section 61 and the thin-walled section 62. The thin-walled section 52 extends along the Z-axis direction from the end 51a toward the lower link member 44. The thin-walled section 53 connects the fixing section 49 to a portion 51c of the main body section 51 located between the end 51a and the end 51b. The portion 51c is located on the end 51b side. The thin-walled section 53 extends along the Z-axis direction from the portion 51c toward the fixing section 59.

[0039] The flexure portion 54 connects the end portion 51b of the main body portion 51 to the fixing portion 63. The flexure portion 54 extends along the Z-axis direction from the end portion 51b toward the lower link member 44. The lower end of the flexure portion 54 is connected to the fixing portion 63. The fixing portion 63 has a through hole 63a that extends along the X-axis direction. The fixing portion 63 is fixed to the end portion 31b by inserting the bolt 12 through the through hole 63a and screwing it into the threaded hole 31c of the end portion 31b of the weighing lever mechanism 30. In other words, the flexure portion 54 is connected to the end portion 31b via the fixing portion 63.

[0040] In the calibration lever mechanism 50, the point of force application P4 is formed by the thin-walled portion 52, the fulcrum P5 is formed by the thin-walled portion 53, and the point of application P6 is formed by the flexure portion 54. Figure 3 schematically shows the positions of the point of force application P4, the fulcrum P5, and the point of application P6. Therefore, the flexure portion 54 is provided between the fulcrum P5 and the fixed portion 63 of the calibration lever mechanism 50. Furthermore, the flexure portion 54 extends along a direction (in this case, the Z-axis direction) that intersects the direction in which the fulcrum P5 and the point of application P6 of the calibration lever mechanism 50 are aligned (i.e., the extending direction of the main body portion 51, which in this case is the Y-axis direction). The flexure portion 54 is designed to be deformable so as to bend in a plane including at least the Y-axis direction and the Z-axis direction (i.e., it has flexibility).

[0041] In the second strain body 4, when the load-receiving portion 41 receives the second load, the load-receiving portion 41, together with the base portion 42, the upper link member 43, and the lower link member 44, displaces downward while maintaining its parallelogram shape. Consequently, the end portion 51a and the thin-walled portion 52 are pulled downward, and the second load is transmitted to the point of force application P4. Then, with the thin-walled portion 53 (fulcrum P5) as the fulcrum, the end portion 51b and the flexure portion 54 (point of application P6) displace upward. If the distance between the point of force application P4 and the fulcrum P5 in the Y-axis direction is L3, the distance between the fulcrum P5 and the point of application P6 in the Y-axis direction is L4, the second load transmitted to the point of force application P4 is W2, and the second load transmitted to the point of application P6 is W21, then the relationship "W2 × L3 = W21 × L4" is satisfied. Here, since portion 51c is located on the end portion 51b side, the relationship "L3 > L4" is satisfied. As a result, the second load transmitted to the point of force application P4 is increased according to the lever ratio L3 / L4 and transmitted to the point of application P6. The second load transmitted to the point of application P6 is transmitted to the fixed part 63 via the flexible part 54.

[0042] In the weighing mechanism 1, the calibration lever mechanism 50 is fixed to the end 31b of the weighing lever mechanism 30 via a fixing part 63. In other words, the other part of the weighing lever mechanism 30 and the calibration lever mechanism 50 is displaced in conjunction with the rotational movement of one of them. On the other hand, the rotational radius of the weighing lever mechanism 30 (main body 31) and the rotational radius of the calibration lever mechanism 50 (main body 51) may be different from each other. Even in this case, in the weighing mechanism 1, the flexure part 54 positioned in front of the fixing part 63 flexes, allowing the weighing lever mechanism 30 and the calibration lever mechanism 50 to rotate without the fixing part 63 becoming rigid.

[0043] The load sensor 8 is a sensor that detects load and is manufactured by hollowing out a relatively thin metal block. As shown in Figure 2, the load sensor 8 has a load receiving part 81, a fixing part 82, and a tuning fork 83.

[0044] A through hole 81a is formed in the load-receiving portion 81. The load-receiving portion 81 is fixed to the end 31b by inserting a bolt 14 through the through hole 81a and screwing it into a threaded hole formed in the end 31b of the weighing lever mechanism 30 of the first strain-generating body 2. In other words, the end 31b is connected to the load-receiving portion 81. As a result, the first strain-generating body 2 transmits the first load (the first load reduced by the weighing lever mechanism 30) to the load-receiving portion 81 via the end 31b. The second strain-generating body 4 also transmits the second load (the second load converted (enlarged) according to the second lever ratio by the calibration lever mechanism 50) to the load-receiving portion 81 via the fixing portion 63 and the end 31b.

[0045] A through hole 82a is formed in the fixing portion 82. The bolt 13 is inserted through the through hole 82a and screwed into a threaded hole formed in the fixing portion 29 of the first strain body 2, thereby fixing the fixing portion 82 to the fixing portion 29.

[0046] The tuning fork 83 receives the first and second loads that the load receiving section 81 receives. The vibration frequency of the tuning fork vibrator in the tuning fork 83 changes according to the magnitude of the load (tension acting on the tuning fork vibrator). In the load sensor 8, a piezoelectric element (not shown) provided on the tuning fork 83 converts the vibration of the tuning fork vibrator into a voltage, and a substrate (not shown) connected to the piezoelectric element counts the period of the voltage and converts it into a frequency. Then, in the load sensor 8, a computer (e.g., a calculation unit 9), such as a microcontroller, processes the data based on the frequency to obtain the first and second loads. As a result, the load sensor 8 detects the first load transmitted from the first strain body 2 (the first load reduced by the weighing lever mechanism 30) and the second load transmitted from the second strain body 4 (the second load amplified by the calibration lever mechanism 50).

[0047] The calculation unit 9 is electrically connected to the load sensor 8 and processes the load detected by the load sensor 8. The calculation unit 9 is composed of a computer including, for example, a processor (CPU), and recording media such as RAM and ROM. The calculation unit 9 calculates a third load by magnifying the second load detected by the load sensor 8 by a predetermined magnification. The calculation unit 9 then sets the third load as the calibration load value and calibrates the load sensor 8. The predetermined magnification is, for example, smaller than the lever ratio L3 / L4 of the calibration lever mechanism 50. The reciprocal L2 / L1 of the lever ratio of the weighing lever mechanism 30 is, for example, smaller than the value obtained by multiplying the lever ratio L3 / L4 of the calibration lever mechanism 50 by the predetermined magnification.

[0048] As an example, the weighing lever mechanism 30 described above reduces the first load of the object to be weighed so that it is 90% or more of the weighing capacity of the load sensor 8. The calibration lever mechanism 50 increases the second load of the weight W so that it is 10% or more of the weighing capacity of the load sensor 8. As an example, the calibration lever mechanism 50 increases the second load of the weight W so that it is 10% or more but less than 90% of the weighing capacity of the load sensor 8. The calculation unit 9 magnifies the second load, which has been increased by the calibration lever mechanism 50, by a predetermined magnification so that it is 90% or more of the weighing capacity of the load sensor 8. In this case, the predetermined magnification is 10 times or less. The weighing capacity of the load sensor 8 refers to the maximum weight that the load sensor 8 can weigh. 90% or more of the weighing capacity refers to the range from 90% of the weighing capacity to the weighing capacity.

[0049] In the weighing mechanism 1 configured as described above, the weighing of the object to be weighed is performed as follows: When the load receiving part 21 receives the first load of the object to be weighed, the load receiving part 21 is displaced downward. Accordingly, the end part 31a and the thin-walled part 32 are pulled downward, and the first load is transmitted to the point of force application P1. The first load transmitted to the point of force application P1 is reduced according to the lever ratio L1 / L2 of the weighing lever mechanism 30 and transmitted to the point of application P3. The first load reduced by the weighing lever mechanism 30 is transmitted to the load receiving part 81 via the end part 31b. The load sensor 8 then detects the first load.

[0050] Furthermore, calibration is performed in the weighing mechanism 1 using a calibration weight W as follows: When the load receiving part 41 receives the second load of the weight W, the load receiving part 41 is displaced downward. Consequently, the end part 51a and the thin-walled part 52 are pulled downward, and the second load is transmitted to the point of force application P4. The second load transmitted to the point of force application P4 is amplified according to the lever ratio L3 / L4 of the calibration lever mechanism 50 and transmitted to the point of application P6. The second load amplified by the calibration lever mechanism 50 is transmitted to the load receiving part 81 via the flexure part 54, the fixed part 63, and the end part 31b. The load sensor 8 then detects the second load. The calculation unit 9 calculates the third load by amplifying the second load by a predetermined magnification. The calculation unit 9 sets the third load as the calibration load value and performs calibration of the load sensor 8.

[0051] An example of weighing using the weighing mechanism 1 described above will be explained with reference to Figure 5. Figure 5 is a schematic diagram showing the weighing lever mechanism and the calibration lever mechanism. In the example in Figure 5, the first load of the object to be weighed is 30 kgf, the second load of the weight W is 1 kgf, the lever ratio of the weighing lever mechanism 30 is 1 / 5, the lever ratio of the calibration lever mechanism 50 is 3, and the predetermined multiplier calculated by the calculation unit 9 is set to 2. When the object to be weighed is loaded, if a load of 30 kgf is applied to the point of force application P1, the load is reduced according to the lever ratio of 1 / 5 and transmitted to the point of application P3. As a result, a tension (tuning fork tension) of 30 kgf × (1 / 5) = 6 kgf acts on the tuning fork 83. The load sensor 8 measures the load of the object to be weighed, which has been reduced by the weighing lever mechanism 30, based on the vibration frequency which changes according to the magnitude of the tuning fork tension.

[0052] When a weight is applied, if a 1 kgf load is applied to the point of force P4, the load is increased according to the lever ratio of 3 and transmitted to the point of application P6. As a result, a tension of 1 kgf × 3 = 3 kgf (tuning fork tension) acts on the tuning fork 83. The load sensor 8 measures the load of the weight W, which has been increased by the calibration lever mechanism 50, based on the vibration frequency which changes according to the magnitude of the tuning fork tension. The calculation unit 9 calculates 6 kgf (third load) by amplifying the 3 kgf load detected by the load sensor 8 by a predetermined magnification of 2 times. The calculation unit 9 sets 6 kgf as the calibration load value and performs calibration of the load sensor 8. [Mechanism of Action and Effects]

[0053] As described above, in the weighing mechanism 1 according to this embodiment, a load sensor 8 for detecting a first load, which is the load of the object to be weighed, and a second load, which is the load of the calibration weight W, is attached to a first strain body 2 that receives the first load of the object to be weighed, and a second strain body 4 that receives the second load of the calibration weight W is detachably attached to the first strain body 2. Therefore, the second strain body 4 can be removed from the first strain body 2, and even when the second strain body 4 is removed from the first strain body 2, the object to be weighed can be weighed using the first strain body 2 and the load sensor 8. Thus, in this weighing mechanism 1, the first strain body 2 for weighing the object to be weighed and the second strain body 4 for calibration can be separated. Furthermore, since the first strain body 2 and the second strain body 4 can be separated in this weighing mechanism 1 as described above, it is possible to ship the product with the second strain body 4 removed from the first strain body 2 to users who do not require calibration of the load sensor 8 using the second strain body 4, thereby reducing costs.

[0054] Furthermore, in the weighing mechanism 1, the second strain-generating body 4 has a calibration lever mechanism 50 that increases the load of the weight W, and the load sensor 8 detects the load of the weight W that has been increased and transmitted from the second strain-generating body 4 by the calibration lever mechanism 50. As a result, the load of the weight W can be increased and transmitted to the load sensor 8, so even if a load sensor 8 capable of detecting a large load is used to improve shock resistance, a large load can be applied to the load sensor 8 using a relatively light weight W, and the load sensor 8 can be calibrated with high accuracy. Therefore, with this weighing mechanism 1, it is possible to improve shock resistance while ensuring calibration accuracy.

[0055] The above functions and effects will be further explained with reference to Figures 6(a) and 6(b). Figures 6(a) and 6(b) are schematic diagrams showing the flow of load transmission in a weighing mechanism. Figure 6(a) shows the flow of load transmission in a weighing mechanism equipped with a second strain body that does not have a lever mechanism, and Figure 6(b) shows the flow of load transmission in the weighing mechanism 1 of the above embodiment. Here, the mass of the object to be weighed is assumed to be 30 kg. In Figure 6(a), the lever ratio of the lever mechanism of the first strain body is set to 1 / 100. In Figure 6(b), the lever ratio of the weighing lever mechanism, the lever ratio of the calibration lever mechanism, and the predetermined magnification are the same as the lever ratio of the weighing lever mechanism 30 and the lever ratio of the calibration lever mechanism 50 shown in Figure 5, respectively.

[0056] In Figure 6(a), the load of the object being weighed, 30 kgf, is reduced according to the lever ratio of 1 / 100 of the lever mechanism of the first strain body. The reduced transmitted load of 300 gf (= 30 kgf / 100) is transmitted to the tuning fork via the second strain body. On the other hand, the load of the internal weight, 150 gf, is transmitted directly to the tuning fork because the second strain body does not have a lever mechanism. This load is amplified by a predetermined magnification of 2 times. The amplified load of 300 gf (= 150 gf × 2) is set as the load value for calibration. In Figure 6(a), if a load sensor capable of detecting large loads (for example, a load sensor with an upper limit of detectable mass of 6 kg) is used to improve impact resistance, the load of the weight needs to be 3 kgf (= 6 kgf / 2) in order to transmit a load of about 6 kgf to the load sensor. Thus, in Figure 6(a), if a load sensor capable of detecting large loads is used, it would be necessary to increase the mass of the calibration weights to ensure calibration accuracy, which is not practical.

[0057] In contrast, in Figure 6(b), the second strain-generating body has a calibration lever mechanism. This means that even when a load sensor capable of detecting large loads (for example, a load sensor with an upper limit of detectable mass of 6 kg) is used, the load of the built-in weight only needs to be a relatively small 1 kgf in order to transmit a load of about 6 kgf to the load sensor. Therefore, according to the weighing mechanism 1 of the above embodiment, a large load can be applied to the load sensor using a relatively light weight, and the load sensor 8 can be calibrated with high accuracy. Thus, according to the weighing mechanism 1, it is possible to improve impact resistance while ensuring calibration accuracy.

[0058] As described above, in the weighing mechanism 1 according to this embodiment, the first strain body 2 has a weighing lever mechanism 30 that reduces the first load, and the load sensor 8 detects the first load that has been reduced and transmitted from the first strain body 2 by the weighing lever mechanism 30. In this way, when a weighing lever mechanism 30 is used in the first strain body 2, the larger the reduction rate of the load in the first strain body 2 (the reciprocal of the lever ratio of the weighing lever mechanism 30, L2 / L1), the larger the change in the lever ratio when the lever mechanism is displaced by an external impact. As a result, external impacts may affect the weighing of the object being weighed. In contrast, in the weighing mechanism 1, as described above, the load of the weight W can be increased and transmitted to the load sensor 8, so a load sensor 8 capable of detecting large loads can be used, and as a result it is possible to maintain a small reduction rate of the weighing lever mechanism 30 in the first strain body 2. Therefore, the weighing mechanism 1 can reduce the impact of external impacts on the weighing of the object being weighed.

[0059] Furthermore, in the weighing mechanism 1 according to this embodiment, the first strain body 2 has an end portion 31b (transmission portion) connected to the load sensor 8, and transmits the first load, which has been reduced (i.e., converted according to the first lever ratio) by the weighing lever mechanism 30, to the load sensor 8 via the end portion 31b. The second strain body 4 has a fixed portion 63 fixed to the end portion 31b, and transmits the second load, which has been increased (i.e., converted according to the second lever ratio) by the calibration lever mechanism 50, to the load sensor 8 via the fixed portion 63 and the end portion 31b. In the second strain body 4, a flexible flex portion 54 is provided between the fulcrum P5 of the calibration lever mechanism 50 and the fixed portion 63, extending in a direction (e.g., the Z-axis direction) that intersects the direction in which the fulcrum P5 and the point of application P6 of the calibration lever mechanism 50 are aligned (e.g., the Y-axis direction).

[0060] As a result, the second strain body 4, which has a lever mechanism, is connected to the end 31b of the first strain body 2, which has another lever mechanism, and the first load from the first strain body 2 and the second load from the second strain body 4 can be easily transmitted to the load sensor 8 via the end 31b. On the other hand, in such a structure, if the radii of rotation around the fulcrums P2 and P5 of the lever mechanisms of the first strain body 2 and the second strain body 4 are different, the fixed parts of them may become stiff, and the operation of the lever mechanism may be hindered. In contrast, in this weighing mechanism 1, a flexible flex part 54 is provided between the fulcrum P5 of the lever mechanism of the second strain body 4 and the fixed part 63. Therefore, the bending of the flex part 54 suppresses the hindering of the operation of the lever mechanism due to stiffness at the fixed part 63. In particular, since the flexure portion 54 extends in a direction that intersects the direction in which the fulcrum P5 and the point of application P6 of the lever mechanism of the second strain body 4 are aligned, the influence of the flexure portion 54 on the lever ratio of the lever mechanism of the second strain body 4 is suppressed.

[0061] Furthermore, in the weighing mechanism 1 according to this embodiment, the first strain body 2 includes a first surface 2s and a second surface 2r opposite to the first surface 2s. The second strain body 4 is attached to the first surface 2s, and the load sensor 8 is attached to the second surface 2r. By providing the load sensor 8 on one side of the first strain body 2 and the second strain body 4 on the other side of the first strain body 2, access to both the load sensor 8 and the second strain body 4 becomes easier.

[0062] Furthermore, the weighing mechanism 1 according to this embodiment includes a weight mounting section 6 on the side of the second strain body 4 opposite to the side facing the first strain body 2, on which a weight W is placed. Thus, a weight mounting section 6 on which a calibration weight W is placed may be provided on the side of the second strain body 4 opposite to the first strain body 2.

[0063] Furthermore, in the weighing mechanism 1 according to this embodiment, the calculation unit 9 calculates a third load by amplifying the second load of the weight W detected by the load sensor 8 (the second load increased by the calibration lever mechanism 50) by a predetermined magnification, and sets the third load as the calibration load value for the load sensor 8. This allows the increase in load from the weight W to be shared between the calibration lever mechanism 50 of the second strain body 4 and the calculation unit 9 when acquiring the calibration load value. As a result, it becomes possible to maintain a small increase rate in the calibration lever mechanism 50 of the second strain body 4, thereby reducing the influence of external impacts on the weighing of the weight W.

[0064] Furthermore, in the weighing mechanism 1 according to this embodiment, the reciprocal L2 / L1 of the lever ratio of the weighing lever mechanism 30 is smaller than the value obtained by multiplying the lever ratio L3 / L4 of the calibration lever mechanism 50 by a predetermined magnification factor. In this way, by maintaining a relatively small reduction ratio of the weighing lever mechanism 30 in the first strain body 2, the influence of external impacts on the weighing of the object to be weighed can be further reduced.

[0065] Furthermore, in the weighing mechanism 1 according to this embodiment, the predetermined magnification is smaller than the lever ratio L3 / L4 of the calibration lever mechanism 50. In this case, the influence of noise superimposed on the signal output from the load sensor 8 can be reduced, so that the load sensor 8 can be calibrated with high accuracy.

[0066] Furthermore, in the weighing mechanism 1 according to this embodiment, the second strain-generating body 4 has a Roberval mechanism composed of a load-receiving portion 41, a base portion 42, an upper link member 43, and a lower link member 44, and the calibration lever mechanism 50 is arranged inside the Roberval mechanism. This makes it possible to reduce the deviation error caused by the load position of the weight W, and as a result, the load sensor 8 can be calibrated with greater accuracy.

[0067] The embodiments described above illustrate one aspect of the present disclosure. Therefore, the present disclosure is not limited to the weighing mechanism 1 described above and can be modified as needed.

[0068] In the above embodiment, the first strain body 2 had a weighing lever mechanism 30 and the second strain body 4 had a calibration lever mechanism 50, but at least one of the first strain body 2 and the second strain body 4 does not need to have a lever mechanism.

[0069] In the above embodiment, the flexure portion 54 (the portion constituting the point of application P6) of the calibration lever mechanism 50 is connected to the end portion 31b of the weighing lever mechanism 30 via the fixed portion 63, and the second strain body 4 transmits the second load, increased by the calibration lever mechanism 50, to the load sensor 8 via the end portion 31b. However, the second strain body 4 may directly transmit the second load, increased by the calibration lever mechanism 50, to the load sensor 8.

[0070] In the above embodiment, the load sensor 8 was a so-called tuning fork type load sensor, but the load sensor 8 may also be a so-called electromagnetic type load sensor. The load sensor 8 may have a lever mechanism, similar to the first strain body 2 and the second strain body 4. Also, the second strain body 4 does not have to have a flexure portion 54. [Explanation of Symbols]

[0071] 1… Measuring mechanism, 2… First tilting body, 4… Second tilting body, 6… Copper distribution unit, 8… Loading center, 30… Measuring tico mechanism, 31b… End (transmission part), 50… Calibration tico mechanism, 63… Fixing part, W… Copper distribution, P5… Support point, P6… Point of action.

Claims

1. A first strain body that receives the first load, which is the load of the object being weighed, A second strain body receiving a second load, which is the load of a calibration weight, A load sensor for detecting the first load transmitted from the first strain body and the second load transmitted from the second strain body, Equipped with, The load sensor is attached to the first strain-generating body, The second strain-generating body is detachably attached to the first strain-generating body. Metering mechanism.

2. The first strain-generating body includes a metering lever mechanism having a first leverage ratio and a transmission unit connected to the load sensor, and transmits the first load, converted by the metering lever mechanism according to the first leverage ratio, to the load sensor via the transmission unit. The second strain generating body has a calibration lever mechanism having a second lever ratio different from the first lever ratio, and a fixed part fixed to the transmission part, and transmits the second load converted by the calibration lever mechanism according to the second lever ratio to the load sensor via the fixed part and the transmission part. A flexible flexure portion is provided between the fulcrum of the calibration lever mechanism and the fixed portion, extending in a direction that intersects the direction in which the fulcrum and the point of application of the calibration lever mechanism are aligned. The weighing mechanism according to claim 1.

3. The calibration lever mechanism has a second lever ratio that increases the second load, The load sensor detects the second load which is amplified and transmitted from the second strain body by the calibration lever mechanism. The weighing mechanism according to claim 2.

4. The weighing lever mechanism has a first lever ratio that reduces the first load, The load sensor detects the first load that is reduced and transmitted from the first strain body by the measuring lever mechanism. The weighing mechanism according to claim 2.

5. The first strain-generating body includes a first surface and a second surface opposite to the first surface, The second strain-generating body is attached to the first surface, The load sensor is attached to the second surface. The weighing mechanism according to claim 1.

6. The second strain-generating body is provided with a weight-holding portion on the surface opposite to the surface facing the first strain-generating body, on which the weight is placed. A weighing mechanism according to any one of claims 1 to 5.

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