Balance weighing pan

Abstract

Providing technology related to the weighing pan of a balance that achieves high-precision repeatability. [Solution] The balance 1 has a weighing pan 2 that receives wind, a pan body 25 having a mesh portion 28, and The plate has an impact absorbing mechanism (34) that absorbs impact loads, and a claw engagement mechanism (41) that connects the plate body (25) to the impact absorbing mechanism (34).

Description

[Technical Field]

[0001] The present invention relates to a technology relating to a weighing pan of a balance that achieves high-precision repeatability. [Background technology]

[0002] FIG. 3 of Patent Document 1 discloses a weighing pan for a load weighing instrument that has a single-axis boss portion on the lower center side, and such a weighing pan is sometimes used in small, high-resolution analytical balances. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2007-333605 Summary of the Invention [Problem to be solved by the invention]

[0004] Compact, high-resolution analytical balances equipped with a draft shield are required to have high repeatability (small variations in measurement values ​​when the same mass is repeatedly placed on and removed from the balance). Furthermore, the accuracy of this repeatability can be adversely affected by slight convection on the weighing pan or by a certain magnitude of impact load when the sample is placed on the pan.

[0005] Furthermore, when it comes to weighing a large object, it is desirable for the weighing pan used in a small, high-resolution analytical balance equipped with a windshield to be large enough to accommodate the object. However, the larger the pan, the greater the adverse effect of convection on the weighing value. It is also desirable for the weighing pan to be as easy to assemble as possible.

[0006] In view of the above problems, the present invention provides a weighing pan for a balance that is easy to assemble and that can reduce the adverse effects of convection and impact loads on the weighing pan even if the weighing pan is large in size. [Means for solving the problem]

[0007] In order to solve the above problem, the inventors considered how to achieve highly accurate repeatability in windy environments by making the weighing pan less susceptible to wind pressure even if the pan is large, and by reducing the impact load on the weighing pan.

[0008] The present invention was made based on the above findings and provides a weighing pan for a balance exposed to wind, which includes a pan body having a mesh portion, an impact absorbing mechanism for absorbing impact loads, and a pawl engagement mechanism for connecting the pan body to the impact absorbing mechanism. The mesh portion reduces the total area of ​​the pan body exposed to wind, thereby reducing wind pressure itself, and the wind passing through the mesh also reduces the moment caused by wind pressure acting near the outer periphery of the weighing pan. The impact absorbing mechanism absorbs impact loads of a predetermined magnitude that occur on the weighing pan. Even if the weighing pan is large, the reduction in wind pressure reduces the adverse effects on the weighing value, and the pawl engagement mechanism allows the impact absorbing mechanism to be easily attached to the pan body.

[0009] The dish body has a ceiling portion having the mesh portion and a central portion, and a cylindrical portion protruding from the lower outer periphery of the ceiling portion, the shock absorbing mechanism has a dish support member having a spring mounting portion formed at a position corresponding to the central portion of the dish body and a plurality of arms formed integrally with the spring mounting portion in a radial direction from the spring mounting portion, and a compression spring placed on the spring mounting portion to urge the dish body to move away from the dish support member, and the claw engagement mechanism has a plurality of claws protruding inward from the lower end of the cylindrical portion of the dish body at positions corresponding to each of the plurality of arms of the dish support member, and engagement portions for the claws formed on the plurality of arms of the dish support member. The shock absorbing mechanism installed on the back surface of the central portion acts to absorb impact loads of a predetermined magnitude, and the mesh portion around the central portion acts to reduce the wind pressure itself and the moment caused by the mesh portion provided on the outer periphery of the dish body. Even if the mesh is enlarged, the moment generated around the periphery by wind is reduced, thereby reducing the adverse effect on the weighing value. Furthermore, the pan body, whose claws engage with the engagement portions formed on the arms of the pan support member, is biased away from the pan support member by a compression spring, thereby positioning and holding the pan body on the pan support member. In this way, the pan body can be easily assembled to the pan support member to form the weighing pan.

[0010] Furthermore, it is more desirable that the engaging portion formed on the arm portion be an engaging recess having a shape that conforms to the outer shape of the claw portion and that engages and holds the claw portion by the biasing force of the compression spring. The mesh portion reduces the wind pressure on the dish body, making it less likely for a moment to be generated around the periphery. Furthermore, with the claw portion of the dish body shifted from the engaging recess of the arm of the dish support member, the dish support member is pushed toward the dish body while receiving the biasing force of the compression spring, and the dish support member is rotated until the engaging recess is positioned at the claw portion. The dish support member is then released, and the claw portion is positioned inside the engaging recess, thereby easily preventing rotation and holding the dish body against the dish support member. When an object is placed on the dish body, which is held by the dish support member while biased by the compression spring, the claw portion slides up and down inside the engaging recess, and impact load is absorbed by the compression spring, thereby reducing the impact load.

[0011] Furthermore, it is more desirable that the mesh portion be formed by a plurality of base portions formed integrally in the radial direction from the central portion above the arms, a plurality of connecting portions that integrally connect the plurality of base portions, and a plurality of openings defined between the plurality of base portions and the connecting portions or the central portion. By placing an object to be weighed on either the central portion or the base portions, or the central portion and the connecting portions, the flexibility of placement is improved, and the openings reduce wind pressure and moment. Furthermore, by positioning the base portions above the arms without being displaced circumferentially from the arms, wind can pass smoothly through the openings, further reducing wind pressure and moment. It is also preferable that the mesh portion has a plurality of openings formed from the vicinity of the center of the dish body to the vicinity of the outermost connecting portion. With this configuration, wind can pass through both the vicinity of the center and the vicinity of the outermost connecting portion, thereby further reducing wind pressure and moment.

[0012] It is also more desirable that the shock absorbing mechanism be held by the mesh-like pan main body. By holding the shock absorbing mechanism on the weighing pan side rather than on the weighing sensor side and moving it together, the weight of the shock absorbing mechanism does not act on the weighing sensor when it is moved, reducing adverse effects on the weighing sensor and making it less likely to break.

[0013] It is also preferable that the dish body has a step portion around the center of the central portion. When a thin plate-shaped weighing object is placed on a flat surface, it is difficult to grasp the edge, but when the thin plate is placed on the step portion, the edge is raised and placed, making it easier to grasp.

[0014] It is also more desirable to have grooves formed from the center of the main pan in the circumferential direction. By placing a rod-shaped object to be weighed in the center and the grooves extending radially from there, the object is held on the weighing pan and is less likely to roll. [Effects of the Invention]

[0015] According to the present invention, even when used in a balance that is used in a windy environment, it is possible to obtain a weighing pan that is easy to assemble and can achieve high-precision repeatability while minimizing the adverse effects of increased wind pressure, moment generation, and impact loads. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing the appearance of a balance equipped with a weighing pan according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the balance of FIG. 1 with the windshield removed. [Figure 3] 1A is a perspective view of the weighing pan and the shock absorbing mechanism according to the present embodiment, as seen obliquely from above, and FIG. 1B is a perspective view of the weighing pan and the shock absorbing mechanism according to the present embodiment, as seen obliquely from below. [Figure 4] 4 is an exploded perspective view of the weighing pan and the shock absorbing mechanism of FIG. 3, seen obliquely from below. FIG. [Figure 5] FIG. 4 is a vertical end view of the weighing pan and the shock absorbing mechanism of FIG. 3. [Figure 6] An explanatory diagram of the procedure for installing an impact absorbing mechanism on a weighing pan, in which (a) is a diagram showing the impact absorbing mechanism positioned on the weighing pan with the engagement recess shifted circumferentially from the claw portion, (b) is a diagram showing the pan support member of the impact absorbing mechanism in (a) pressed against the weighing pan against the biasing force of the compression coil spring, (c) is a diagram showing the pan support member in (b) rotated so that the engagement recess is positioned below the claw portion, and (d) is a diagram showing the pan support member in (c) released and the claw portion engaged with the engagement recess by the biasing force of the compression coil spring. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, a preferred embodiment of the weighing pan of the balance of the present invention will be described below with reference to FIGS.

[0018] Figures 1 and 2 show an electronic balance 1 having a weighing pan of the present invention. Figure 2 shows the electronic balance 1 with the windshield 10 removed. As shown in Figure 1, the electronic balance 1 has a case 3 that houses a weighing mechanism (not shown) including a mass sensor such as an electromagnetic balance or load cell connected to the weighing pan 2 (see Figure 2), as well as a control unit (not shown) that controls various operations of the electronic balance. The front side of the case 3 also has a control panel 4. The top surface of this control panel 4 has a display 4a that displays weighing results and the like, and multiple touch panel switches 4b for various operations.

[0019] As shown in FIG. 1, a bottomless box-shaped windshield 10 consisting of a front panel 7, a pair of left and right side doors (only the right side door 8 is shown), a back panel (not shown), and a top door 9 is provided on the top panel 6 of the case 3, and the rectangular parallelepiped internal space forms the measuring chamber. The front panel 7, the pair of left and right side doors 8, the back panel, and the top door 9 that make up the windshield 10 are made of transparent materials, allowing the measuring chamber to be seen through; however, for convenience, the measuring chamber is not visible in FIG. 1. The windshield 10 keeps the measuring chamber closed during measurement, minimizing the effect of airflow during measurement, such as airflow from an air conditioner, a person's breathing during measurement, or airflow generated by a person walking, on the load-bearing portion centered on the measuring pan 2 as wind pressure and affecting the measurement.

[0020] As shown in FIG. 1, support boxes 11 and 12 are disposed at the left and right upper ends of windshield 10. Within support box 11, the upper end of right side door 8 is slidably suspended inside restricting member 13, and within support box 12, the upper end of left side door (not shown) is slidably suspended inside restricting member 14 (FIG. 2). Handles 15 and 16 for opening and closing are provided on right side door 8 and left side door, respectively. Furthermore, support boxes 11 and 12 slidably support the left and right side ends of top door 9. Top door 9 is manually slid and has a knob 17.

[0021] Handles 15, 16 of the right side door 8 and left side door (not shown) shown in FIG. 1 are detachably connected to engaging and disengaging members 18, 19, respectively, and the engaging and disengaging members 18, 19 are connected by a connecting plate 20 disposed below the case 3. The handles 15, 16 are connected and disconnected by switching the knobs 21a, 22a of the connecting member 21. When the knobs 21a, 22a are lowered to connect the handles 15, 16, both the right side door 8 and the left side door slide simultaneously, and when the knobs 21a, 22a are raised to disconnect the handles, they can slide independently.

[0022] Next, a preferred embodiment of a weighing pan of a balance equipped with a shock absorbing mechanism will be described with reference to Figures 3 to 6. The weighing pan 2 is composed of a pan main body 25, a shock absorbing mechanism 34, and a pawl engagement mechanism 41.

[0023] The dish main body 25 shown in Figures 3 to 5 is composed of a ceiling portion 25a, a cylindrical portion 25b, and claw portions 25c. The ceiling portion 25a has a circular central portion 27 and a mesh portion 28 integrally formed around the central portion 27. The cylindrical portion 25b protrudes downward from the outer periphery of the ceiling portion 25a. A plurality of claw portions 25c are integrally formed at the lower end 25d of the cylindrical portion 25b, protruding inward from the lower end 25d and spaced equally circumferentially. Each of the claw portions 25c has a semicircular shape. The shock absorbing mechanism 34 includes a truncated conical compression coil spring 36 and a dish support member 37, and is positioned and held on the dish main body 25 by a claw engagement mechanism 41 (described later). The number of claw portions 25c is not limited to the number shown in Figures 3, 4, and 6 (four), as long as there are multiple claw portions, and they do not have to be spaced equally circumferentially.

[0024] 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 28b1 to 28b4, and openings 28c1 to 28c3. The plurality of base portions 28a are each formed integrally with the central portion 27 and extend radially from a center O1 of the central portion 27 at equal intervals. The plurality of base portions 28a are also connected together by a plurality of connecting portions 28b1 to 28b4 that are concentric and annular and centered on the center O1. The connecting portions 28b1 to 28b4 are composed of, in order from closest to the center O1, an inner connecting portion 28b1, a middle connecting portion 28b2, and a middle connecting portion 28b3, and an outer connecting portion 28b4 that connects the tips of the four base portions 28a. Inner connecting portion 28b1 and middle connecting portions 28b2, 28b3 are formed at equal intervals between the outer periphery of central portion 27 and outer connecting portion 28b4. An inner opening 28c1 separated by multiple base ribs 28a is formed between the outer periphery of central portion 27 and inner connecting portion 28b1, and middle openings 28c2, 28c3 separated by multiple base ribs 28a are formed between inner connecting portion 28b1 and middle connecting portion 28b2, and between middle connecting portion 28b2 and middle connecting portion 28b3, respectively, in order of decreasing distance from center O1. Furthermore, an outer opening 28c4 separated by multiple base ribs 28a is formed between middle connecting portion 28b3 and outer connecting portion 28b4 near the outermost periphery of plate main body 25.

[0025] 3 and 4, mesh portion 28 has multiple openings 28c1-28c4 in the circumferential direction, thereby reducing the total area of ​​pan body 25 that is subjected to convection, so that pan body 25 is less susceptible to wind pressure from convection within windshield 10 that occurs when right side door 8 is opened, compared to a conventional solid weighing pan without mesh portion 28. As a result, mesh portion 28 further expands the area provided on the outer periphery of center portion 27 so that large objects to be weighed, such as filters, can be placed on it. This reduces the adverse effects of convection wind pressure on the weighing value, even if the size of pan body 25 is increased, thereby achieving highly accurate repeatability in electronic balance 1.

[0026] 3 and 4, mesh portion 28 has multiple openings arranged radially from inner opening 28c1 near center 27 of pan body 25 to outer opening 28c4 near outer connecting portion 28b4, allowing convection currents generated within windshield 10 in FIG. 1 to pass evenly through inner opening 28c1 near center 27, middle openings 28c2 and 28c3 in the middle of mesh portion 28, and outer opening 28c4 near outer connecting portion 28b4, thereby reducing wind pressure on the outer peripheral edge of pan body 25. As a result, mesh portion 28 reduces the moment generated on pan body 25 by wind pressure from convection currents within windshield 10, and further reduces adverse effects on weighing values, thereby achieving highly accurate repeatability.

[0027] 3(a) and 3(b) has a ring-shaped step portion 30 along the outer peripheral end 25e of the dish main body portion 25. The step portion 30 is an inclined portion that slopes diagonally downward from the outer peripheral end 25e toward the inside of the dish main body portion 25, and is formed over the entire outer connecting portion 28b4 and in the area from the inner end 30a located to the side of the outer opening 28c4 in the base portion 28a to the outer outer peripheral end 25e. The step portion 30 forms the central portion 27 one step lower than the outer peripheral end 25e of the dish main body portion 25.

[0028] If all thin plate-shaped weighing objects that fit in the area inside the inner end 30a on the ceiling 25a of the dish main body 25 are placed in that area, the 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 objects.However, if one end of such an object is placed against the outer peripheral end 25e of the dish main body 25, which is higher than the central part 27, so that the end is raised above the central part 27, it will be easier to grasp the end of the object after weighing.

[0029] 3(a), the dish main body 25 has a pair of grooves 32 on the step portion 30. The pair of grooves 32 are respectively formed on a straight line L1 that passes through the center O1 of the central portion 27 and a pair of base portions 28a that face each other across the center O1. Each of the pair of grooves 32 is formed as a V-shaped recess, but may also be formed as an arc-shaped recess.

[0030] As shown in Figure 3(a), a thin, rod-shaped weighing object is placed inside both of the two grooves 32, thereby being positioned and held so as not to roll from the center O1 of the dish main body 25. In this embodiment, a pair of grooves 32 is provided at positions facing each other across the center O1, but two or more pairs may be provided as long as they are positioned facing each other across the center O1.

[0031] 3 to 6, the shock absorbing mechanism 34 positioned and held on the dish main body 25 will be described. The shock absorbing mechanism 34 has a compression coil spring 36 and a dish support member 37.

[0032] As shown in Figures 3(b) to 5, the dish support member 37 has a central spring mounting portion 37a and multiple arms 37b and shafts 37c integrally projecting radially outward from the spring mounting portion 37a. The spring mounting portion 37a is positioned directly below the center of the dish main body 25 when coupled to the dish main body 25 by a claw engagement mechanism 41 (described later). A bottomed, circular hole-shaped spring housing portion 37e is provided on the upper surface of the spring mounting portion 37a to house a compression coil spring 36 having a tapered, truncated cone shape. The multiple arms 37b are formed at positions corresponding to the respective base ribs 28a of the mesh portion 28. The multiple arms 37b are also formed directly below the base rib 28a, circumferentially spaced apart from the openings 28c1 to 28c4 to avoid interference with the openings 28c1 to 28c4. The length from the center O1 to the tip of the arm 37b is formed to match the distance from the center O1 to the inner circumference of the cylindrical portion 25b of the pan main body 25. The shaft 37c is a solid shaft with a truncated cone shape that tapers downward, and holds the weighing pan 2 on the electronic balance 1.

[0033] 3(b), 4, and 5, an engagement recess 37d is formed in each of the tip portions 37f of the arm portions 37b. The engagement recess 37d is a semicircular, ceiling-shaped engagement recess that conforms to the shape of the claw portion 25c. It is provided at a position corresponding to each of the claw portions 25c and is formed as an engagement portion for engaging the semicircular claw portion 25c. The vertical depth of the engagement recess 37d is formed to be greater than the thickness of the claw portion 25c. Furthermore, as shown in FIG. 5, the thickness d1 of the tip portion 37f of the arm portion 37b having the engagement recess 37d must be less than the vertical length d2 from the underside of the central portion 27 of the dish main body 25 to the upper surface of the claw portion 25c. The claw engagement mechanism 41 is formed by the claw portion 25c of the dish main body 25 and the engagement recess 37d of the arm portion 37b of the dish support member 37.

[0034] Next, a method for assembling the shock absorbing mechanism 34 to the dish main body 25 will be described with reference to Figures 4 to 6. First, the compression coil spring 36 shown in Figure 4 is placed in the spring storage portion 37e of the dish support member 37 shown in Figure 5. Next, as shown in Figure 6(a), the arm portion 37b is shifted circumferentially from the base portion 28a so that the claw portion 25c does not interfere with the engagement recess 37d, and the dish support member 37 is positioned, and the dish support member 37 is lowered in the direction D1 while resisting the biasing force of the compression coil spring 36, and pressed against the dish main body 25.

[0035] As shown in FIG. 6(b), after pressing the dish support member 37 against the dish main body 25, rotate the dish support member 37 in the direction D2 around the central axis O2 to align the engagement recess 37d with the position of the claw portion 25c, as shown in FIG. 6(c). When the dish support member 37 is released in this state, the dish support member 37 is biased by the compression coil spring 36 to move upward from the dish main body 25, and rises in the direction D3. At this time, as shown in FIG. 6(d), the claw portion 25c slides within the engagement recess 37d of the dish support member 37 while engaged with it, and contacts the ceiling of the engagement recess 37d. As shown in FIG. 5, the dish main body 25 is prevented from rotating in the circumferential direction by engaging the claw portion 25c with the engagement recess 37d, and the back surface of the dish main body 25 is kept spaced apart from the top surface of the dish support member 37. In addition, the dish receiving member 37 can be easily removed from the dish main body 25 by performing the series of steps from FIG. 6(a) to FIG. 6(d) in reverse.

[0036] According to the weighing pan 2 of this embodiment shown in Figure 6, the compression coil spring 36 of the shock absorbing mechanism 34 urges the pan main body 25 and the pan support member 37, with the claw portion 25c and the engagement recess 37d engaged, in a direction away from each other to prevent rotation, thereby making it possible to easily attach and detach the shock absorbing mechanism 34 from the pan main body 25 without using a screw mechanism or the like.

[0037] When the dish main body 25, to which the impact absorbing mechanism 34 is attached, receives an impact load when an object to be weighed is placed on it, it descends relative to the dish support member 37 against the biasing force of the compression coil spring 36, and the impact is absorbed as the compression coil spring 36 further compresses within the spring storage section 37e.

[0038] As shown in Figure 5, the shock absorbing mechanism 34 is fixed to the back surface of the central portion 27 of the pan body 25 and absorbs the shock load when an object to be weighed is placed on the pan body 25. Meanwhile, the mesh portion 28 around the central portion 27 of the pan body 25 allows convection currents within the windshield 10, which occur when the right side door 8 is opened, to pass through the multiple openings 28c. The mesh portion 28 of the weighing pan 2 reduces the total area of ​​the pan body 25 that is subjected to convection currents. This makes the pan body less susceptible to wind pressure due to convection currents within the windshield 10 compared to a conventional solid weighing pan without the mesh portion 28, and the shock absorbing mechanism 34 also absorbs the shock load.

[0039] In the weighing pan 2 of this embodiment, in addition to the effect of the mesh portion 28 making the pan body less susceptible to wind pressure caused by convection generated within the windshield 10, the impact absorbing mechanism 34 has a synergistic effect of absorbing impact loads, further reducing the adverse effects on the weighing values ​​of the electronic balance 1 to which the weighing pan 2 is attached, thereby achieving a synergistic effect of achieving highly accurate repeatability.

[0040] Furthermore, the shock absorbing mechanism 34 during movement is held by the pan main body 25 rather than by the weighing sensor (not shown) of the electronic balance 1 to form the weighing pan 2, and is moved together with the weighing pan. As a result, the weight of the shock absorbing mechanism 34 does not act when the weighing sensor inside the electronic balance 1 moves, reducing the adverse effects on the weighing sensor and making it less likely to break. [Explanation of symbols]

[0041] 1. Electronic balance 2 Weighing pan 25 Plate body 25a Ceiling section 25b Cylindrical part 25c Claw part 27 Central part 28 Mesh section 28a Base bone 28b1~28b3 Middle connection part 28b4 External connection part 28c1~28c3 Middle opening 28c4 outer opening 30 Step 32 Groove 34 Shock absorption mechanism 36 Compression coil spring 37 Pan support member 37a Spring rest 37b Arm 41 Claw engagement mechanism

Claims

1. On the weighing pan of a balance exposed to wind, a dish body having a central portion and a mesh portion around the central portion; an impact absorbing mechanism that absorbs impact loads; a claw engagement mechanism that connects the dish body to the shock absorbing mechanism; and The dish main body portion is a central portion, a ceiling portion having the mesh portion around the central portion, and a cylindrical portion protruding from a lower outer periphery of the ceiling portion, The shock absorbing mechanism includes: The dish support member has a spring mounting portion formed at a position corresponding to the center of the dish main body portion and a plurality of arms formed integrally with the spring mounting portion in a radial direction, and a compression spring mounted on the spring mounting portion to bias the dish main body portion away from the dish support member, The claw engagement mechanism includes: The tray support member has a plurality of claw portions protruding inward from the lower end of the cylindrical portion of the tray main body portion at positions corresponding to each of the plurality of arm portions of the tray support member, and an engagement portion for the claw portions formed on the plurality of arm portions of the tray support member, The mesh portion is formed by a plurality of base portions formed integrally in the radial direction from the central portion above the arm portion, a plurality of connecting portions that connect the plurality of base portions together, and a plurality of openings defined between the plurality of base portions and the connecting portions or the central portion.

2. The weighing pan of the balance described in Claim 1, characterized in that the engaging portion formed on the arm portion has a shape that follows the outer shape of the claw portion and is an engaging recess that engages and holds the claw portion by the biasing force of the compression spring.

3. A weighing pan for a balance as described in claim 1, characterized in that the openings in the mesh portion are formed in multiple positions from near the central portion to near the outermost connecting portion of the connecting portion.

4. A weighing pan of a balance as described in claim 1, characterized in that the shock absorbing mechanism is held in the pan main body portion.

5. A weighing pan for a balance as described in claim 1, characterized in that the pan main body portion has a stepped portion formed around the center of the central portion.

6. A weighing pan for a balance as described in claim 1, characterized in that it has a groove portion formed from the center of the pan main body portion in the outer circumferential direction.

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