Metrology

Abstract

To provide a weighing mechanism that can improve impact resistance while ensuring calibration accuracy. [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 second strain body 4 has a calibration lever mechanism 50 that increases the second load, and the load sensor 8 detects the second load that has been increased and transmitted from the second strain body 4 by the calibration lever mechanism 50.

Description

Technical Field

[0001] The present disclosure relates to a metering mechanism.

Background Art

[0002] Patent Document 1 describes a load measurement mechanism including a bellows part, a first force conversion part connected to the bellows part, a second force conversion part connected to the first force conversion part, and a force sensor attached to the second force conversion part. In this load measurement mechanism, the load applied to the force receiving part of the first force conversion part is reduced according to the lever ratio of a lever provided in the first force conversion part and transmitted to the force sensor. Further, in this load measurement mechanism, by applying the load of a calibration weight to the force receiving part of the second force conversion part, the force receiving part is displaced downward, and the displacement is transmitted to the force sensor. Patent Document 2 describes a weighing mechanism having the same configuration as the load measurement mechanism.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the above technical field, improvement of shock resistance is desired. As one means for improving shock resistance, it is conceivable to use a force sensor capable of detecting a larger load. On the other hand, in order to calibrate the force sensor more accurately, it is desirable to apply a load as large as possible to the force sensor within the detectable range of the force sensor. That is, from the requirement of shock resistance, when a force sensor capable of detecting a larger load is adopted, it is necessary to increase the mass of the calibration weight to ensure the accuracy of calibration, which is not practical.

[0005] This disclosure aims to provide a weighing mechanism that can improve impact resistance while ensuring calibration accuracy. [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 second strain body has a calibration lever mechanism that increases the second load, and the load sensor detects the second load which has been increased and transmitted from the second strain body by the calibration lever mechanism.

[0007] In this weighing mechanism, the second strain-generating body has a calibration lever mechanism that increases the load of the weight, and the load sensor detects the load of the weight that has been increased and transmitted from the second strain-generating 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 when a load sensor capable of detecting a large load is used to improve shock 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, this weighing mechanism makes it possible to improve shock resistance while ensuring calibration accuracy.

[0008] The weighing mechanism relating to this disclosure may also be [2] "the weighing mechanism according to [1], wherein the first strain body has a weighing lever mechanism 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 in 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 this weighing mechanism, as described above, the load of the weight can be increased and transmitted to the load sensor, so a load sensor capable of detecting large loads can be used, and as a result, the reduction rate of the lever mechanism in the first strain body can be kept small. Therefore, with this weighing mechanism, the influence of external impacts on the weighing of the object to be weighed can be reduced.

[0009] The weighing mechanism relating to this disclosure may also be [3] "a weighing mechanism according to [1] or [2], comprising a calculation unit that calculates a third load by amplifying the second load detected by the load sensor by a predetermined magnification and sets the third load as a calibration load value." In this case, when obtaining the calibration load value, the increase in load from the weight can be shared between the lever mechanism of the second strain body (calibration lever mechanism) and the calculation unit. As a result, it becomes possible to keep the increase rate in the lever mechanism of the second strain body small, and the influence of external impacts on weighing the weight can be reduced.

[0010] The weighing mechanism relating to this disclosure may also be [4] "the weighing mechanism according to [2], which includes a calculation unit that calculates a third load by magnifying the second load detected by the load sensor by a predetermined magnification and sets the third load as a calibration load value, wherein the reciprocal of the lever ratio of the weighing lever mechanism is smaller than the value obtained by multiplying the lever ratio of the calibration lever mechanism by the predetermined magnification." In this way, by maintaining a relatively small reduction ratio of the lever mechanism in the first strain body, the influence of external impacts on the weighing of the object to be weighed can be further reduced.

[0011] The weighing mechanism relating to this disclosure may also be the weighing mechanism described in [3] or [4], wherein the predetermined magnification is smaller than the lever ratio of the calibration lever mechanism. In this case, the influence of noise superimposed on the signal output from the load sensor can be reduced, and the load sensor can be calibrated with high accuracy.

[0012] The weighing mechanism relating to this disclosure may also be [6] "the weighing mechanism according to any one of [1] to [5], wherein the second strain-generating body has a Roberval mechanism, and the calibration lever mechanism is located inside the Roberval mechanism." In this case, the deviation error caused by the load position of the weight can be reduced, and as a result, the load sensor can be calibrated with greater accuracy.

[0013] The weighing mechanism relating to this disclosure may also be [7] "a weighing mechanism according to any one of [1] to [6], further comprising the weight, wherein the calibration lever mechanism increases the second load of the weight so that it is 10% or more of the weighing capacity of the load sensor." For example, when using a calculation unit to amplify the second load detected by the load sensor by a predetermined magnification so that it is 90% or more of the weighing capacity of the load sensor, the predetermined magnification by the calculation unit can be set to 10 times or less. This reduces the influence of disturbances, and thus the load sensor can be calibrated with greater accuracy. [Effects of the Invention]

[0014] According to this disclosure, it is possible to provide a weighing mechanism that can improve impact resistance while ensuring calibration accuracy. [Brief explanation of the drawing]

[0015] [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]

[0016] 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.

[0017] 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 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. 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 being calibrated. The weight W is a built-in weight provided by the weighing mechanism 1. 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 elongated 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, one 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, the 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 weighed. The first deflecting body 2 has 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 of the first deflecting body 2 in the Y-axis direction (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. The base portion 22 corresponds to the other end portion of the first deflecting body 2 in the Y-axis direction (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, while 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 21 and the base portion 22 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 to each other. The first deflecting body 2 has a Roberval mechanism constituted 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 page in Figure 3). 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 page in Figure 3). A bolt 13 is screwed into this screw hole from the other side in the X-axis direction to fix the load sensor 8 to the first strain body 2.

[0026] The first strain-generating body 2 further includes a weighing lever mechanism 30. The weighing lever mechanism 30 is a mechanism for reducing the first load. The weighing lever mechanism 30 has a main body portion 31 and thin-walled portions 32 and 33. When viewed from the X-axis direction, the weighing lever mechanism 30 is located inside the Roberval mechanism of the first strain-generating 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). 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). 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-generating 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 is a mechanism for increasing 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 positioned inside the Roberval mechanism of the second strain-generating 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 thin-walled section 52 constitutes the point of force application P4, the thin-walled section 53 constitutes the fulcrum P5, and the flexure section 54 constitutes the point of application P6. Figure 3 schematically shows the positions of the point of force application P4, the fulcrum P5, and the point of application P6. In the second strain body 4, when the load receiving section 41 receives the second load, the load receiving section 41, together with the base section 42, the upper link member 43, and the lower link member 44, displaces downward while maintaining a parallelogram shape. Consequently, the end section 51a and the thin-walled section 52 are pulled downward, and the second load is transmitted to the point of force application P4. Then, the end section 51b and the flexure section 54 (point of application P6) are displaced upward with the thin-walled section 53 (fulcrum P5) as the fulcrum. If L3 is the distance between the point of force application P4 and the fulcrum P5 in the Y-axis direction, L4 is the distance between the fulcrum P5 and the point of application P6 in the Y-axis direction, W2 is the second load transmitted to the point of force application P4, and W21 is the second load transmitted to the point of application P6, then the relationship "W2 × L3 = W21 × L4" is satisfied. Here, since part 51c is located on the end 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 flexure part 54.

[0041] 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.

[0042] 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.

[0043] 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 increased by the calibration lever mechanism 50) to the load-receiving portion 81 via the end 31b.

[0044] 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.

[0045] 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).

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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]

[0052] As explained above, 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, 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] The first strain-generating 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-generating body 2 by the weighing lever mechanism 30. Thus, when the weighing lever mechanism 30 is used in the first strain-generating body 2, the larger the reduction rate of the load in the first strain-generating 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-generating body 2. Therefore, the weighing mechanism 1 can reduce the impact of external impacts on the weighing of the object being weighed.

[0057] 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. 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 keep the increase rate in the calibration lever mechanism 50 of the second strain body 4 small, thereby reducing the influence of external impacts on the weighing of the weight W.

[0058] The reciprocal of the lever ratio L2 / L1 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.

[0059] 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, allowing the load sensor 8 to be calibrated with high accuracy.

[0060] 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 positioned inside the Roberval mechanism. This reduces 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.

[0061] The weighing mechanism 1 is equipped with a weight W, and the calibration lever mechanism 50 increases the second load of the weight W so that it becomes 10% or more of the weighing capacity of the load sensor 8. For example, when the calculation unit 9 is used to amplify the second load detected by the load sensor 8 by a predetermined magnification so that it becomes 90% or more of the weighing capacity of the load sensor 8, the predetermined magnification by the calculation unit 9 can be set to 10 times or less. This reduces the influence of disturbances, and thus the load sensor 8 can be calibrated with greater accuracy. [Differentiation]

[0062] 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.

[0063] In the above embodiment, the first strain-generating body 2 had a lever mechanism 30 for weighing, but the first strain-generating body 2 does not necessarily have to have a lever mechanism.

[0064] 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 fixing 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. In this case, the load sensor 8 may be directly fixed to the second strain body 4.

[0065] 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 also have a lever mechanism, similar to the first strain body 2 and the second strain body 4. [Explanation of Symbols]

[0066] 1...Measuring mechanism, 2...First strain body, 4...Second strain body, 8...Load sensor, 9...Calculation unit, 30...Measuring lever mechanism, 50...Calibration lever mechanism, W...Weight.

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 second strain-generating body has a calibration lever mechanism for increasing 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. Metering mechanism.

2. The first strain-generating body has a measuring lever mechanism for reducing 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 1.

3. The system includes a calculation unit that calculates a third load by magnifying the second load detected by the load sensor by a predetermined magnification, and sets the third load as a calibration load value. The weighing mechanism according to claim 1.

4. The calculation unit calculates a third load by magnifying the second load detected by the load sensor by a predetermined magnification, and sets the third load as a calibration load value. The reciprocal of the lever ratio of the weighing lever mechanism is smaller than the value obtained by multiplying the lever ratio of the calibration lever mechanism by the predetermined multiplier. The weighing mechanism according to claim 2.

5. The predetermined magnification is smaller than the lever ratio of the calibration lever mechanism. The weighing mechanism according to claim 3.

6. The second strain-generating body has a Roberval mechanism, The calibration lever mechanism is located inside the Roberval mechanism. The weighing mechanism according to claim 1.

7. The aforementioned weight is further comprising: The calibration lever mechanism increases the second load of the weight so that it becomes 10% or more of the weighing capacity of the load sensor. The weighing mechanism according to claim 1.

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