Measuring pan of a balance scale

Abstract

Providing technology related to weighing pans for balances that achieve high precision and repeatability. [Solution] The weighing pan 2 of the balance 1, which is exposed to wind, is provided with a pan body 25 having a mesh portion 28 and an impact absorption mechanism 34 that absorbs impact loads.

Description

Technical Field

[0001] The present invention relates to a weighing pan of a balance that realizes high-precision repeatability.

Background Art

[0002] FIG. 3 of Patent Document 1 discloses a weighing pan of a load measuring instrument provided with a uniaxial boss portion on the lower side of the center. Such a weighing pan may be used for a small and high-resolution analytical balance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A small and high-resolution analytical balance with a windbreak is required to have high-precision repeatability (the variation range of measurement values when the same mass is repeatedly placed and removed is small). Also, the accuracy of such repeatability deteriorates when the weighing pan is subjected to slight convection or when a shock load of a certain magnitude is applied when the weighed object is placed.

[0005] In addition, when assuming the weighing of a weighed object of a large size, the weighing pan used for a small and high-resolution analytical balance with a windbreak is preferably enlarged according to the size of the weighed object so that it can be placed thereon. However, there is a problem that the larger the size, the greater the adverse effect on the weighing value due to convection.

[0006] In view of the above problems, the present invention provides a weighing pan of a balance that can reduce the adverse effects of convection and shock load on the weighing pan even when the size is large.

Means for Solving the Problems

[0007] To solve the above problems, the inventors considered how to achieve high-precision repeatability in windy environments by making the weighing pan less susceptible to wind pressure even with a large size, and by reducing the impact load generated on the weighing pan.

[0008] The present invention is based on the above findings and provides a weighing pan for a balance that is exposed to wind, comprising a pan body with a mesh portion and an impact absorption mechanism that absorbs impact loads. The mesh portion reduces the total surface area of ​​the weighing pan body that is exposed to wind, thereby reducing the wind pressure itself, and the moment caused by wind pressure acting near the outer circumference of the weighing pan is also reduced as the wind passes through the mesh. The impact absorption mechanism absorbs impact loads of a predetermined size that occur on the weighing pan. Even if the size of the weighing pan is large, the reduction in wind pressure reduces the adverse effect on the weighing value.

[0009] Furthermore, it is preferable that the weighing pan of the balance has a central portion and a mesh portion surrounding the central portion, and that the shock absorption mechanism is provided on the back surface of the central portion. The shock absorption mechanism installed on the back surface of the central portion absorbs an impact load of a predetermined magnitude, and the mesh portion around the central portion reduces the amount of wind pressure itself and the moment generated by the mesh portion on the outer circumference of the pan body. Even if the outer diameter of the mesh portion is increased, the moment generated on the outer circumference by the wind is reduced, thus reducing the adverse effect on the weighing value.

[0010] Furthermore, it is more desirable that the mesh portion be formed by a plurality of base sections integrally formed radially from the central portion, a plurality of connecting sections integrally connecting the plurality of base sections, and a plurality of openings defined between the plurality of base sections and the connecting sections. Placing the weighing object on either the central portion and the base sections, or on the central portion and the connecting sections, improves the flexibility of placement, and the openings reduce wind pressure and moment.

[0011] Furthermore, it is more desirable that multiple openings in the mesh portion are formed from near the center of the dish body to near the outermost connecting portion. This configuration allows air to pass through both near the center and near the outermost connecting portion, further reducing wind pressure and moment.

[0012] Furthermore, it is more desirable that the shock absorption mechanism be fixed to the mesh-like pan body. When the shock absorption mechanism moves with the weighing pan rather than on the weighing sensor side, the weight of the shock absorption mechanism does not act on the weighing sensor when it moves, reducing adverse effects on the weighing sensor and making the weighing sensor less likely to break.

[0013] Furthermore, it is more desirable for the plate body to have a stepped portion around the center of the central part. When a thin plate-shaped object is placed on a flat surface, it is difficult to grasp the edges, but when the plate is propped up on the stepped portion, the edges are raised, making it easier to grasp.

[0014] Furthermore, it is more desirable that the pan body has grooves formed outwards from the center. By placing a rod-shaped object on the central part and the grooves radiating from it, the object is held on the weighing pan and less likely to roll around.

[0015] Furthermore, it is more desirable that the pan body has a notch formed by cutting out a portion of its outer circumference. By placing a portion of the object being weighed on the notch on the weighing pan, it becomes easier to grasp the portion placed within the notch. [Effects of the Invention]

[0016] According to the present invention, a weighing pan can be obtained that, even when used in a balance used in a windy environment, is less affected by increased wind pressure, moment generation, and impact loads, and can achieve high accuracy and repeatability. [Brief explanation of the drawing]

[0017] [Figure 1] This is a perspective view showing the external appearance of a balance equipped with a weighing pan according to an embodiment of the present invention. [Figure 2]It is a perspective view of a balance with the wind guard in FIG. 1 removed. [Figure 3] It is a perspective view of the weighing pan and the shock absorption mechanism according to the present embodiment as viewed obliquely from above. [Figure 4] It is an exploded perspective view of the weighing pan and the shock absorption mechanism in FIG. 3 as viewed obliquely from below. [Figure 5] It is a longitudinal end view of the shock absorption mechanism obtained by cutting the weighing pan in FIG. 3 along the line I-I.

Mode for Carrying Out the Invention

[0018] Next, a preferred embodiment of the balance weighing pan of the present invention will be described below based on FIGS. 1 to 5.

[0019] FIGS. 1 and 2 show an electronic balance 1 having a weighing pan of the balance of the present invention. FIG. 2 shows a view with the wind guard 10 removed from the electronic balance 1. As shown in FIG. 1, the electronic balance 1 includes a case 3 provided therein with a weighing mechanism (not shown) including a mass sensor such as an electromagnetic balance type or a load cell type connected to a weighing pan 2 (see FIG. 2), and a control unit (not shown) that controls various operations of the electronic balance. Further, a control panel 4 is provided on the front side of the case 3. On the upper surface of this control panel 4, a display unit 4a for displaying weighing results and the like, and a plurality of touch panel type switches 4b for various operations are provided.

[0020] As shown in FIG. 1, on the top plate 6 of the case 3, a wind guard 10 having a bottomless box shape and consisting of a front plate 7, a pair of left and right side doors (only the right side door 8 is shown), a back plate (not shown), and an upper door 9 is provided, and a rectangular parallelepiped internal space forms a weighing chamber. The front plate 7, the pair of left and right side doors 8, the back plate, and the upper door 9 constituting the wind guard 10 are made of a transparent body, and the weighing chamber is visible, but in FIG. 1, for the sake of convenience, the weighing chamber is shown in an invisible state. The wind guard 10 closes the inside of the weighing chamber during weighing, and prevents air flows during weighing, such as the wind of an air conditioner, the breath of a person during weighing, and the air flow generated when a person walks, from acting as wind pressure on the load-bearing part centered on the weighing pan 2 and affecting the weighing as much as possible.

[0021] As shown in FIG. 1, support boxes 11 and 12 are arranged at the upper left and right ends of the windshield 10. Inside the support box 11, the upper end of the right side door 8 is slidably suspended inside the regulating member 13. Inside the support box 12, the upper end of the left side door (not shown) is slidably suspended inside the regulating member 14 of FIG. 2. The right side door 8 and the left side door are respectively provided with opening and closing handles 15 and 16. Further, the support boxes 11 and 12 slidably support the left and right side ends of the upper surface door 9. The upper surface door 9 is manually slidable and provided with a knob 17.

[0022] The handles 15 and 16 of the right side door 8 and the left side door (not shown) shown in FIG. 1 are detachably connected to the detachable members 18 and 19 respectively. The detachable members 18 and 19 are connected by a connecting plate 20 arranged under the case 3. The connection and release of the handles 15 and 16 are achieved by switching the knobs 21a and 22a of the connecting member 21. When the knobs 21a and 22a are lowered to connect the handles 15 and 16, the right side door 8 and the left side door slide simultaneously. When the knobs 21a and 22a are raised to release the connection, they can slide independently.

[0023] Next, with reference to FIGS. 3 to 5, a preferred embodiment of the weighing pan of the balance provided with the shock absorption mechanism will be described. The weighing pan 2 is composed of a pan main body portion 25 and a shock absorption mechanism 34.

[0024] As shown in FIGS. 3 to 5, the pan main body portion 25 has a circular central portion 27, a mesh portion 28 integrally formed around the central portion 27, and a cylindrical portion 29 integrally formed directly below the central portion 27. The shock absorption mechanism 34 has a rubber material 35, compression coil springs 36, a pan receiving member 37, and a pan receiving holding member 38, and is fixed to the cylindrical portion 29 of the pan main body portion 25.

[0025] As shown in Figures 3 to 5, the mesh portion 28 has a concentric circular shape with respect to the central portion 27. The mesh portion 28 is composed of a plurality of base portions 28a, connecting portions 28b, and openings 28c. Each of the plurality of base portions 28a is integrally formed with the central portion 27 and extends radially at equal intervals from the center O1 of the central portion 27. The plurality of base portions 28a are connected by a plurality of annular connecting portions 28b centered on the center O1. The connecting portion 28b is composed of an inner connecting portion 28b1 integrally formed on the outer circumference of the central portion 27, an outer connecting portion 28b3 that connects the tips of each base portion 28a (6 locations), and a middle connecting portion 28b2 provided between the inner connecting portion 28b1 and the outer connecting portion 28b3 to connect each base portion 28a. Furthermore, multiple internal openings 28c1, separated by multiple base bone portions 28a, are formed circumferentially between the internal connecting portion 28b1 and the middle connecting portion 28b2, and multiple external openings 28c2, separated by multiple base bone portions 28a, are formed circumferentially between the middle connecting portion 28b2 and the external connecting portion 28b3. The external openings 28c2 are formed outside the internal openings 28c1. Note that the number of multiple base bone portions 28a, connecting portions 28b, and openings 28c is not limited to the number disclosed in Figures 3 and 4.

[0026] As shown in Figure 5, the shock absorption mechanism 34 is fixed to the back surface of the central part 27 of the pan body 25 and absorbs the impact load when an object is placed on the pan body 25. On the other hand, the mesh part 28 around the central part 27 of the pan body 25 allows the convection inside the draft shield 10 that occurs when the right side door 8 is opened to pass through multiple openings 28c. Because the mesh part 28 reduces the total surface area of ​​the pan body 25 that is subjected to convection, the weighing pan 2 is less susceptible to wind pressure from convection inside the draft shield 10 compared to conventional solid weighing pans without the mesh part 28, and the shock absorption mechanism 34 absorbs the impact load. As a result of this action, even if the size of the pan body 25 of the weighing pan 2 in this embodiment is increased by expanding the mesh portion 28 to accommodate large weighing objects such as filters, the total surface area exposed to convection is smaller than that of conventional weighing pans. Furthermore, the shock absorption mechanism reduces the adverse effect on the weighing value of the electronic balance 1 to which the weighing pan 2 is attached, thereby achieving high accuracy and repeatability.

[0027] Furthermore, the mesh portion 28 has an outer opening 28c2 extending radially outward from the inner opening 28c1. This allows convection generated inside the windbreak 10 to pass not only through the inner opening 28c1 near the central part 27 of the pan body portion 25, but also through the outer opening 28c2 near the outer connecting portion 28b3 that constitutes the outer edge of the pan body portion 25. This reduces the wind pressure on the outer periphery of the pan body portion 25. As a result, the mesh portion 28 reduces the moment generated in the pan body portion 25 by the wind pressure of convection inside the windbreak 10, and further reduces the adverse effect on the weighing value, thereby achieving highly accurate repeatability.

[0028] Furthermore, the dish body portion 25 shown in Figure 3 has a stepped portion 30 at the boundary between the central portion 27 and the internal connecting portion 28b1 of the mesh portion 28. The central portion 27 is formed to be one step lower than the upper surface of the mesh portion 28 by the stepped portion 30.

[0029] In the pan body 25, if thin, plate-shaped weighing objects that fit inside the central part 27 are all placed on the central part 27, the weighing objects will be placed so that they stick to the flat surface of the central part 27, making it difficult to grasp both ends of the weighing objects. However, if one end of such weighing objects is propped up against the stepped part 30, and the end is raised away from the central part 27, it becomes easier to grasp the end of the weighing object after weighing.

[0030] Furthermore, as shown in Figure 3, the pan body portion 25 has a notch portion 31 on its outer circumference, which is shaped like a part of the mesh portion 28 that has been cut out. The notch portion 31 has a shape in which the middle connecting portion 28b2 and the outer connecting portion 28b3 have been removed from a pair of adjacent base portions 28a. By placing a part of the object to be weighed on the notch portion on the weighing pan 2, it becomes easier to grasp the part of the object that protrudes into the notch portion 31.

[0031] Furthermore, as shown in Figure 3, the dish body portion 25 has grooves 32 on the connecting portion 28b of the mesh portion 28. The grooves 32 are formed at positions indicated by reference numerals 32a, 32b, 32c, and 32d on a straight line L1 passing through the center O1 of the central portion 27 and the notch portion 31. Specifically, the grooves 32 are provided at two locations in the inner connecting portion 28b1: position 32a facing the notch portion 31 and position 32b opposite position 32a across the center O1; and at one location each in the middle connecting portion 28b2 and the outer connecting portion 28b3: positions 32c and 32d extending radially outward from position 32b to the central portion 27, for a total of four locations. All four grooves 32 are formed as arc-shaped recesses, and each groove 32 is formed such that the lowest point of the recess is flush with the upper surface of the central portion 27.

[0032] As shown in Figure 3, the elongated rod-shaped weighing object is positioned and held in place so as not to roll off the center O1 of the pan body 25 by being placed inside the four grooves 32 indicated by reference numerals 32a, 32b, 32c, and 32d on the connecting portion 28b. Furthermore, the rod-shaped weighing object within the grooves 32 is held stably in contact with both the connecting portion 28b and the central portion 27 because the lowest point of the recess is flush with the upper surface of the central portion 27. In addition, the grooves 32 may be formed in six locations on the connecting portion 28b on a straight line that does not pass through the notch 31, but in this embodiment, they are formed on a straight line L1 that passes through the notch 31, which is more desirable because it can hold the elongated rod-shaped weighing object in a way that prevents it from rolling, and it also makes it easier to grasp the end of the rod-shaped weighing object placed on the notch 31.

[0033] As shown in Figures 4 and 5, the shock absorption mechanism 34 includes a cylindrical portion 29 of the plate body 25, a rubber material 35, a compression coil spring 36, a plate receiving member 37, and a plate receiving holding member 38.

[0034] As shown in Figures 4 and 5, a cylindrical portion 29 is integrally formed directly below the central portion 27, concentric with the central portion 27, and a male threaded portion 29a is provided on the outer circumference of the cylindrical portion 29. The inside of the cylindrical portion 29 is formed as a housing portion 29b for the rubber material 35. The rubber material 35 is a cylindrical cushioning member, and has an outer diameter that is slightly smaller by a certain length than the inner diameter of the housing portion 29b, and a height that is less than or equal to the inner height of the housing portion 29b. The compression coil spring 36 has an outer diameter smaller than the outer diameter of the rubber material 35.

[0035] Furthermore, the disc-bearing member 37 shown in Figures 4 and 5 is composed of a ceiling portion 37a, a first shaft portion 37b, and a second shaft portion 37c, all formed coaxially and integrally from top to bottom. The ceiling portion 37a has a bottomed cylindrical shape with a cylindrical portion 37a2 integrally projecting upward from the outer circumference of the bottom portion 37a1. The inner diameter of the cylindrical portion 37a2 is formed to be slightly larger than the outer diameter of the compression coil spring 36, and the lower end of the compression coil spring 36 is held on top of the bottom portion 37a1 and inside the cylindrical portion 37a2. The first shaft portion 37b has a cylindrical shape with a constant outer diameter, and the second shaft portion 37c is smoothly integrally formed with the lower end of the first shaft portion 37b and has a frustoconical shape that tapers downward.

[0036] Furthermore, the pan holder member 38 shown in Figures 4 and 5 has a three-stage cylindrical shape in which a first cylindrical portion 38a, a second cylindrical portion 38b, and a third cylindrical portion 38c, each having different outer and inner diameters, are integrally formed by a flange portion 38d and a crank portion 38e. The first cylindrical portion 38a is integrally formed with the lower end of the second cylindrical portion 38b by a flange portion 38d that protrudes horizontally outward from its upper end. The second cylindrical portion 38b is integrally formed with the lower end of the third cylindrical portion 38c via the crank portion 38e at a position offset horizontally outward by the thickness of the second cylindrical portion 38b from its upper end.

[0037] As shown in Figure 5, the inner diameter of the circular hole 38f of the first cylindrical portion 38a is formed to be slightly larger by a certain length than the outer diameter of the first shaft portion 37b of the pan-receiving member 37. The second cylindrical portion 38b is formed to have the same inner and outer diameters as the cylindrical portion 29 of the pan body portion 25. Furthermore, the inner diameter of the second cylindrical portion 38b is formed to be slightly larger by a certain length than the outer diameter of the cylindrical portion 37a2 of the ceiling portion 37a of the pan-receiving member 37. In addition, the inside of the third cylindrical portion 38c is provided with a female threaded portion 38g that can be screwed onto the male threaded portion 29a formed on the outer circumference of the cylindrical portion 29 of the pan body portion 25.

[0038] The shock absorption mechanism 34 is assembled and fixed to the pan body 25 as follows. First, the pan receiving member 37 is positioned and held with its top portion 37a inside the second cylindrical portion 38b and on the flange portion 38d, with its first shaft portion 37b and second shaft portion 37c inserted into the circular hole 38f of the pan receiving holding member 38. Next, the compression coil spring 36 is held inside the cylindrical portion 37a2 of the top portion 37a and on the bottom portion 37a1, and with the upper end of the compression coil spring 36 in contact with the rubber material 35 placed in the storage portion 29b of the cylindrical portion 29 of the pan body 25, the third cylindrical portion 38c of the pan receiving holding member 38 is screwed and fixed up to the upper end of the cylindrical portion 29 of the pan body 25. The compression coil spring 36 is compressed and expandable vertically, biasing the pan receiving member 37 to the pan receiving holding member 38. The pan body 25 is fixed to the balance via the second shaft portion 37c of the pan support member 37. When an object is placed on the pan body 25 and the fixed weighing pan 2 is subjected to an impact load, the pan body 25 and the pan support holding member 38 descend relative to the pan support member 37 against the biasing force of the compression coil spring 36, and the impact is absorbed as the compression coil spring 36 compresses further within the second cylindrical portion 38b. In addition, minute pressures acting on the pan body 25 due to convection generated inside the draft shield are absorbed by the rubber material 35.

[0039] Furthermore, the shock absorption mechanism 34 is fixed to the pan body 25 of the electronic balance 1, rather than to the weighing sensor (not shown), and forms the weighing pan 2. Because the shock absorption mechanism 34 moves together with the weighing pan, the weight of the shock absorption mechanism 34 does not act on the weighing sensor when it moves within the electronic balance 1. This reduces adverse effects on the weighing sensor and makes it less likely to break. [Explanation of Symbols]

[0040] 1. Electronic balance 2 Weighing pan 25 Plate body 27 Central part 28 Mesh section 28a Base bone 28b Connection part 28c opening 30 Step section 31 Notch 32 grooves 34. Shock absorption mechanism 35 Rubber material 36 Compression coil spring 37 Pan support member 38. Dish holder retaining member

Claims

1. In the weighing pan of a balance scale that is exposed to wind, A dish body having a mesh portion, An impact absorption mechanism that absorbs impact loads, A weighing pan for a balance scale, characterized by having the following features.

2. The plate body has a central portion and a mesh portion surrounding the central portion. The weighing pan of the balance according to claim 1, characterized in that the shock absorption mechanism is provided on the back surface of the central part.

3. The weighing pan of a balance according to claim 2, characterized in that the mesh portion is formed by a plurality of base portions integrally formed radially from the central portion, a plurality of connecting portions integrally connecting the plurality of base portions, and a plurality of openings defined between the plurality of base portions and the connecting portions.

4. The weighing pan of a balance according to claim 3, characterized in that the openings in the mesh portion are formed in multiple locations from near the central portion to near the outermost connecting portion of the connecting portion.

5. The weighing pan of a balance according to claim 1 or 2, characterized in that the shock absorption mechanism is fixed to the pan body.

6. The weighing pan for a balance according to claim 2, characterized in that the pan body portion has a stepped portion formed around the center of the central portion.

7. The weighing pan for a balance according to claim 1 or 2, characterized in that it has a groove formed outward from the center of the pan body.

8. The weighing pan for a balance according to claim 1 or 2, characterized in that it has a notch formed by cutting out a part of the outer circumference of the pan body.

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