CN108369129B

CN108369129B - Electronic balance

Info

Publication number: CN108369129B
Application number: CN201580085415.6A
Authority: CN
Inventors: 饭塚淳史
Original assignee: Shimadzu Corp
Current assignee: Shimadzu Corp
Priority date: 2015-12-22
Filing date: 2015-12-22
Publication date: 2020-07-31
Anticipated expiration: 2035-12-22
Also published as: JPWO2017109869A1; CN108369129A; WO2017109869A1; DE112015007215B4; DE112015007215T5; JP6551543B2

Abstract

The 1 st frame (4) is supported from below by the 2 nd frame (5) over a wide range from the vicinity below the electromagnetic force generating device (6) to the vicinity below the fixing member (42), and the fixing member (42) is fixed to the end of the extension (321) on the movable column (31) side. Thus, even when the load of the dial (2) or the self weight of the block mechanism body (3) is measured, when the load acts in the direction of pressing the 1 st frame (4) downward via the fixing member (42), the load can be transmitted from the 1 st frame (4) to the 2 nd frame (5) in the vicinity below the fixing member (42), and the load can be transmitted to the base member (1) in the vicinity below the electromagnetic force generating device (6) via the 2 nd frame (5). Therefore, the deformation of the 1 st frame (4) can be prevented, and the offset error characteristic can be improved.

Description

Electronic balance

Technical Field

The present invention relates to an electronic balance in which a weighing pan is attached to a block-shaped mechanism body formed by digging through a base material.

Background

An electronic balance of the so-called electromagnetic force balance type includes, for example, an electromagnetic force generating device having a movable coil and a magnetic circuit. The magnetic circuit is configured to include a permanent magnet, a yoke, and the like, and can form a static magnetic field inside. The moving coil is disposed in a static magnetic field formed by a magnetic circuit and is displaceable in the axial direction thereof.

The weighing pan on which the object to be measured is placed is coupled to the movable coil via a lever, and the movable coil coupled to the lever is displaced as the lever is displaced by a load of the object to be measured. At this time, the displacement of the lever is detected by the detector, and the current flowing to the movable coil is feedback-controlled so that the lever does not displace, whereby the mass of the object to be measured can be measured from the current value.

Such an electronic balance includes, for example, a roberval mechanism that restricts the displacement of a weighing pan in the vertical direction. The roberval mechanism is a mechanism for coupling a movable column to which a weighing pan is attached and a fixed column fixed to a base member of an electronic balance main body, and is configured to: the roberval mechanism flexes as the movable column is displaced by the load of the object to be measured. The lever is coupled to the movable column and is displaced as the movable column is displaced.

Conventionally, there is known a block-shaped mechanism body formed by digging through one base material, and a roberval mechanism, a movable column, a fixed column, and a lever as described above are integrally formed (for example, see patent document 1 below). In this way, by adopting an integrated and uniform structure, the responsiveness and the temperature characteristics can be improved.

Fig. 6 is a schematic cross-sectional view showing a configuration example of a conventional electronic balance. This electronic balance is an electromagnetic force balance type electronic balance, and includes a weighing pan 101, a block mechanism body 102, a 1 st frame 103, a 2 nd frame 104, a base member 105, an electromagnetic force generating device 106, and the like.

The block mechanism body 102 has the following constitution: the movable column 102a, the fixed column 102b, the roberval mechanism 102c, and the like are integrally formed by digging through one base material. Upper and lower ends of the movable column 102a and the fixed column 102b are coupled to each other by a pair of roberval mechanisms 102c extending in the horizontal direction. As the movable column 102a moves up and down, the pair of roberval mechanisms 102c are thereby deflected, and the displacement of the movable column 102a can be restricted in the vertical direction.

A weighing pan 101 is mounted on the upper surface of the movable column 102 a. The fixed column 102b is formed with an elongated extension 102d, the extension 102d extends to the movable column 102a side along the roberval mechanism 102c, and one end side of the 1 st frame 103 is fixed to the extension 102d by a plurality of bolts 107.

The other end side of the 1 st frame 103 extends to the rear of the fixed column 102b (the side opposite to the movable column 102a side) in the horizontal direction, and an electromagnetic force generating device 106 is attached to the other end side. Thereby, the electromagnetic force generating device 106 is held by the 1 st frame 103 together with the block-shaped mechanism body 102 at a position adjacent to the fixed column 102 b.

The 2 nd frame 104 is fixed to the 1 st frame 103, and supports the 1 st frame 103 below the electromagnetic force generating device 106. By supporting the 2 nd frame 104 by the base member 105, the block mechanism body 102 can be held in a state where the movable column 102a can be displaced in the vertical direction. In this way, since the relatively heavy electromagnetic force generating device 106 is attached to the base member 105 in a state of being supported from below by the 2 nd frame 104, it is possible to prevent the positional relationship between the electromagnetic force generating device 106 and the block mechanism body 102 from being shifted due to vibration or the like at the time of conveyance.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4035724

Disclosure of Invention

Technical problem to be solved by the invention

However, in the conventional electromagnetic force balance type electronic balance as described above, the 1 st frame 103 may be deformed by a load applied to the weighing pan 101, and thus the offset error characteristic may be deteriorated. Further, when the weight of the block mechanism 102 is large, the 1 st frame 103 is deformed before the object to be measured is placed on the weighing pan 101, and the offset error characteristic may be deteriorated.

That is, as shown by the arrows in fig. 6, the load of the weighing pan 101 and the self weight of the block mechanism 102 act in the direction of pressing the 1 st frame 103 downward via the bolts 107. Therefore, there are problems as follows: the boundary position 108 between the portion of the 1 st frame 103 supported by the 2 nd frame 104 and the portion not supported serves as a fulcrum, and the 1 st frame 103 is easily deformed.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electronic balance capable of improving offset error characteristics.

Solution for solving the above technical problem

The electronic balance of the present invention comprises: a weighing plate, a block mechanism body, a No. 1 frame, a No. 2 frame, an electromagnetic force generating device and a base member. The weighing pan is mounted with a measurement object. The block-shaped mechanism body is formed by digging through a base material and is provided with the weighing disc. The 1 st frame is fixed to the block mechanism body by a plurality of fixing members. The 2 nd frame is fixed to the 1 st frame. The electromagnetic force generating device is mounted to the 1 st frame or the 2 nd frame. The base member is in the vicinity below the electromagnetic force generating device and supports the 2 nd frame.

The block-shaped mechanism body is integrally formed with a movable column, a fixed column, and a roberval mechanism. The weighing pan is mounted to the movable column. The 1 st frame is fixed to the fixing column. The roberval mechanism couples the movable column and the fixed column to limit displacement of the weighing pan in a vertical direction. An elongated extension portion is formed on the fixed column, and the extension portion is fixed to the 1 st frame by the fixing member at least at the end portion of the extension portion on the movable column side, and extends to the movable column side along the roberval mechanism. The electromagnetic force generating device is arranged adjacent to the fixed column. The 2 nd frame supports the 1 st frame from below in a range from below vicinity of the electromagnetic force generating device to below vicinity of the fixing fixed to the end portion of the extension portion on the movable column side.

With this configuration, the 1 st frame can be supported from below by the 2 nd frame over a wide range from below and near the electromagnetic force generating device to below and near the fixing element fixed to the end portion of the extension portion on the movable column side. Thus, even when the load of the weighing pan or the self weight of the block-shaped mechanism acts in the direction of pressing the 1 st frame downward via the fixing member, the load can be transmitted from the 1 st frame to the 2 nd frame in the vicinity below the fixing member, and the load can be transmitted to the base member in the vicinity below the electromagnetic force generating device via the 2 nd frame. Therefore, the deformation of the 1 st frame can be prevented, thereby improving the offset error characteristic.

The 1 st frame may include a pair of split frames that sandwich the block-shaped mechanism body in a width direction orthogonal to a longitudinal direction of the extension portion and are fixed to the extension portion by the fixing members, respectively. In this case, the pair of separation frames may be fixed to the 2 nd frame, respectively.

According to such a configuration, since the 1 st frame is separated into the pair of separation frames and the block mechanism body is held by the pair of separation frames, the 1 st frame can be prevented from being deformed by the internal stress. However, in this case, since the 1 st frame is separated into a pair of separation frames, each separation frame may be easily deformed by a load of the weighing pan or a self weight of the block mechanism. In the present invention, the 1 st frame is supported from below by the 2 nd frame over a wide range from below the electromagnetic force generating device to below the fixing member fixed to the end portion of the extension portion on the movable column side, so that the 1 st frame is prevented from being deformed, and the offset error characteristic can be improved.

Preferably, the electromagnetic force generating means is mounted to the 2 nd frame.

With this configuration, the load of the electromagnetic force generating device can be directly received by the 2 nd frame. This can reduce the load acting on the 1 st frame, and therefore can effectively prevent the 1 st frame from being deformed, thereby further improving the offset error characteristics.

Effects of the invention

According to the present invention, since the 1 st frame is supported from below by the 2 nd frame over a wide range from below and near the electromagnetic force generating device to below and near the fixing member fixed to the end portion of the extension portion on the movable column side, it is possible to prevent the 1 st frame from being deformed, and to improve the offset error characteristic.

Drawings

Fig. 1 is a perspective view showing an example of the configuration of an electronic balance according to an embodiment of the present invention.

Fig. 2 is a top view of the electronic balance of fig. 1.

Fig. 3 is a side view of the electronic balance of fig. 1.

Fig. 4 is a front view of the electronic balance of fig. 1.

Fig. 5 is a sectional view a-a of the electronic balance in fig. 2.

Fig. 6 is a schematic cross-sectional view showing a configuration example of a conventional electronic balance.

Detailed Description

Fig. 2 is a top view of the electronic balance of fig. 1. Fig. 3 is a side view of the electronic balance of fig. 1. Fig. 4 is a front view of the electronic balance of fig. 1. Fig. 5 is a cross-sectional view along a-a of the electronic balance of fig. 2.

In this electronic balance, each member is provided on a base member 1, and a measurement object is placed on a weighing pan 2 to enable measurement. In fig. 1 and 2, the base member 1 and the weighing pan 2 of the electronic balance are not shown. In fig. 3 to 5, a part of the base member 1 is omitted and shown. The electronic balance of the present embodiment includes, in addition to the base member 1 and the weighing pan 2, a block-shaped mechanism body 3, a 1 st frame 4, a 2 nd frame 5, an electromagnetic force generating device 6, a lever extension member 7, a detector 8, a shutter 9, and the like.

The weighing pan 2 is mounted to the block mechanism body 3. The block-shaped mechanism body 3 is formed by digging through a single rectangular prism-shaped base material made of, for example, an aluminum alloy, and is configured to integrally form the movable column 31, the fixed column 32, the roberval mechanism 33, the lever 34, the connecting portion 35, and the like. However, the block-shaped mechanism body 3 is not limited to a quadrangular prism-shaped member made of an aluminum alloy, and may be formed of other materials or shapes.

The movable column 31 is, for example, a quadrangular prism-shaped portion extending in the vertical direction, and the weighing pan 2 is mounted on the upper surface thereof. The movable column 31 constitutes one end portion of the block mechanism body 3 in the horizontal direction. On the other hand, the fixing post 32 constitutes the other end portion of the block-shaped mechanism body 3 in the horizontal direction, and the block-shaped mechanism body 3 is supported at the fixing post 32 by fixing the fixing post 32 to the 1 st frame 4.

The roberval mechanism 33 extends horizontally from one end to the other end of the block mechanism body 3, and couples the movable column 31 and the fixed column 32. In the present embodiment, the upper end portions and the lower end portions of the movable column 31 and the fixed column 32 are coupled to each other by a pair of roberval mechanisms 33. Thus, the paired roberval mechanisms 33 constitute the upper surface and the lower surface of the block mechanism body 3.

Each roberval mechanism 33 has: a flat plate-like beam 331 extending in the horizontal direction; the flexible portion 332 connects both end portions of the beam 331 to the movable column 31 and the fixed column 32, respectively. The flexible portion 332 is formed to have a thickness smaller than that of the beam 331, and thus is easily elastically deformed. When a load of the object to be measured is applied to the weighing pan 2, the flexible portion 332 of each roberval mechanism 33 flexes, and the movable column 31 is displaced vertically downward. At this time, the displacement of the weighing pan 2 can be restricted in the vertical direction by the respective roberval mechanisms 33.

The fixed column 32 in the present embodiment is formed with an elongated extension portion 321, and the extension portion 321 extends horizontally along the roberval mechanism 33 to the movable column 31 side. The extension portion 321 is disposed between the pair of roberval mechanisms 33, and a predetermined interval is formed between the extension portion and the pair of roberval mechanisms 33, whereby each roberval mechanism 33 can be prevented from coming into contact with it during bending.

The lever 34 is coupled to the movable column 31 via a coupling portion 35. As shown in fig. 5, the coupling portion 35 extends in the vertical direction between the extension portion 321 of the fixed column 32 and the movable column 31, has a lower end portion coupled to the movable column 31 via a force point spring 351, and has an upper end portion coupled to one end portion of the lever 34 via a force point spring 352. The force point spring 352 is a very thin plate spring having a thickness of 0.1mm or less, for example, and moves up and down together with the coupling portion 35 in accordance with the displacement of the movable column 31.

The lever 34 extends horizontally along the roberval mechanism 33, and its central portion is coupled to the extension portion 321 of the fixed column 32 via a fulcrum spring 353. The fulcrum spring 353 is formed of a very thin plate spring having a thickness of, for example, 0.1mm or less, as in the force point spring 352. Accordingly, when the coupling portion 35 moves up and down in accordance with the displacement of the movable column 31, a force in the up-down direction is applied to one end portion of the lever 34 via the force point spring 352, and the lever 34 swings about the fulcrum spring 353.

The lever extension member 7 is attached to the other end portion of the lever 34, i.e., the side opposite to the force point spring 352 side with respect to the fulcrum spring 353, by a fixing member 341 made of, for example, a bolt and a nut. In this example, the pair of lever extension members 7 are provided on both sides across the block mechanism body 3 in the width direction D2 (horizontal direction orthogonal to the longitudinal direction D1) so as to extend along the longitudinal direction D1 of the block mechanism body 3, respectively. One end of each lever extension member 7 in the longitudinal direction D1 is fixed to each lever 34.

The 1 st frame 4 is composed of a pair of separation frames 41, and the pair of separation frames 41 are provided on both sides with the block mechanism body 3 interposed therebetween in the width direction D2, each separation frame 41 is a member formed of, for example, aluminum and having an elongated shape along the longitudinal direction D1, and a cross section orthogonal to the longitudinal direction D1 is formed in a L shape.

Each of the separation frames 41 is fixed to the block mechanism body 3 by a plurality of fixing members 42 made of, for example, bolts and nuts. More specifically, as shown in fig. 5, each of the anchors 42 is fixed so as to penetrate the extension portion 321 of the block mechanism body 3 in the width direction D2. Of these plurality of fixing members 42, at least one fixing member 42 is fixed to each separation frame 41 at the end of the extension portion 321 on the movable column 31 side.

The 2 nd frame 5 is formed of, for example, aluminum, and integrally forms the following members: a bottom panel 51 for supporting the 1 st frame 4 from below; side panels 52 extending upward from both ends of the bottom panel 51 in the width direction D2; the back plate 53 extends upward from one end of the bottom plate 51 in the longitudinal direction D1. The separate frames 41 constituting the 1 st frame 4 are fixed to the bottom plate 51 of the 2 nd frame 5 by fasteners 43 made of, for example, bolts and nuts.

As shown in fig. 4 and 5, a cutout 511 is formed in the bottom panel 51 of the 2 nd frame 5 at a position corresponding to the lower side of the block mechanism body 3. Thus, the block-shaped mechanism bodies 3 are arranged so as not to contact the bottom plate 51, and even when the roberval mechanisms 33 of the block-shaped mechanism bodies 3 are deflected by a load applied to the weighing pan 2, the block-shaped mechanism bodies 3 do not contact the bottom plate 51.

The block mechanism body 3 is mounted between the fixing post 32 and the back plate 53 of the 2 nd frame 5 with a space. Thus, a space is formed between the fixing post 32 of the block mechanism body 3 and the back plate 53, and the electromagnetic force generating device 6 is disposed in the space. The electromagnetic force generating device 6 is attached to the bottom plate 51 of the 2 nd frame 5 in a state of being disposed adjacent to the rear side (the opposite side to the movable column 31 side) with respect to the fixed column 32 of the block mechanism body 3.

As shown in fig. 5, the electromagnetic force generating device 6 includes a moving coil 61 and a magnetic circuit 62. The magnetic circuit 62 includes, for example, a permanent magnet and a yoke, and can form a static magnetic field therein. The moving coil 61 is disposed in a static magnetic field formed by the magnetic circuit 62, and is held so as to be displaceable in the axial direction, i.e., the vertical direction.

One end of each lever extension member 7 in the longitudinal direction D1 is fixed to the lever 34 of the block mechanism body 3 as described above, and the other end thereof is fixed to the movable coil 61 of the electromagnetic force generating device 6. Therefore, when the movable column 31 is displaced in the vertical direction by the load against the weighing pan 2 and the lever 34 swings about the fulcrum spring 353, the movable coil 61 fixed to the lever 34 via each lever extension member 7 is displaced in the vertical direction.

The detector 8 is a device for detecting the displacement of the lever 34, and includes, for example, a light emitting element and a light receiving element mounted on the circuit board 81. In the present embodiment, the shutter 9 is coupled to the lever extension member 7 attached to the lever 34, and a part of light incident from the light emitting element to the light receiving element can be shielded by the shutter 9. Accordingly, the amount of light blocked by the shutter 9 changes with the displacement of the lever 34, and the displacement of the lever 34 can be detected by detecting the change in the amount of light by the light receiving element.

When measuring the mass of the object to be measured, the displacement of the lever 34 is detected by the detector 8, and the current flowing to the movable coil 61 is feedback-controlled so that the lever 34 does not displace. In this case, the larger the mass of the object to be measured becomes, the larger the value of the current flowing to the movable coil 61 becomes, and therefore the mass of the object to be measured can be measured based on the value of the current flowing to the movable coil 61.

In the present embodiment, the 2 nd frame 5 is supported by the base member 1 in the vicinity below the electromagnetic force generating device 6. The 2 nd frame 5 extends from the lower vicinity of the electromagnetic force generating device 6 to the lower vicinity of the fixing member 42, and supports the 1 st frame 4 (each separation frame 41) from below, the fixing member 42 being fixed to the end portion of the extending portion 321 of the block mechanism body 3 on the movable pole 31 side.

That is, the bottom plate 51 and the side plate 52 of the 2 nd frame 5 extend to the lower vicinity of the anchor 42 closest to the movable column 31 side among the anchors 42 that fix the 1 st frame 4 to the extension portion 321 of the block mechanism body 3. Preferably, the bottom panel 51 and the side panel 52 extend toward the movable column 31 in a range from the end of the block-shaped mechanism body 3 on the fixed column 32 side to two thirds or more of the length along the longitudinal direction D1 of the block-shaped mechanism body 3.

As a result, as shown by the arrow in fig. 3, even when the load of the weighing pan 2 or the self weight of the block mechanism body 3 acts in the direction of pressing the 1 st frame 4 downward via the fixing member 42, the load can be transmitted from the 1 st frame 4 to the 2 nd frame 5 in the vicinity below the fixing member 42, and the load can be transmitted to the base member 1 in the vicinity below the electromagnetic force generating device 6 via the 2 nd frame 5. This prevents deformation of the 1 st frame 4, thereby improving the offset error characteristics.

In the present embodiment, since the 1 st frame 4 is separated into the pair of separation frames 41 and the block mechanism body 3 is held by the pair of separation frames 41, the 1 st frame 4 can be prevented from being deformed by internal stress. However, in this case, since the 1 st frame 4 is separated into the pair of separation frames 41, there is a possibility that each separation frame 41 is easily deformed against the load of the weighing pan 2 or the self weight of the mass mechanism body 3. In the present embodiment, the separation frames 41 of the 1 st frame 4 are supported from below by the 2 nd frame 5 over a wide range from the vicinity below the electromagnetic force generating device 6 to the vicinity below the anchor 42 fixed to the end portion of the movable column side 31 of the extension portion 321, so that the 1 st frame 4 can be prevented from being deformed, and the offset error characteristic can be improved.

Further, in the present embodiment, since the electromagnetic force generating device 6 is attached to the 2 nd frame 5, the load of the electromagnetic force generating device 6 can be directly received by the 2 nd frame 5. This can reduce the load acting on the 1 st frame 4, and therefore can effectively prevent the 1 st frame 4 from being deformed, thereby further improving the offset error characteristics.

The vicinity below the electromagnetic force generating device 6 includes, for example, a range within 1cm or several cm adjacent to the vicinity in the longitudinal direction D1 from directly below, in addition to the vicinity directly below the electromagnetic force generating device 6. Similarly, the vicinity below the anchor 42 includes, for example, a range within 1cm or several cm adjacent to the vicinity in the longitudinal direction D1 from the vicinity directly below the anchor 42, in addition to the vicinity directly below the anchor 42.

In the above embodiment, the configuration in which the 1 st frame 4 is separated into the pair of separation frames 41 has been described. However, the present invention may be applied to a configuration in which the 1 st frame 4 is not separated into the pair of separation frames 41. The electromagnetic force generating device 6 is not limited to the structure mounted on the 2 nd frame 5, and may be mounted on the 1 st frame 4.

The 1 st frame 4 and the 2 nd frame 5 are not limited to being formed of aluminum, and may be formed of other materials, but are preferably formed of the same material or the same kind of material as the block body 3 in order to suppress the influence of thermal expansion and thermal contraction on the offset error characteristics.

Description of the reference numerals

1 base member

2 weighing pan

3 block-shaped mechanism body

41 st frame

5 No. 2 frame

6 electromagnetic force generating device

7 Lever extension Member

8 Detector

9 shutter

31 movable post

32 fixed column

33 Robowell mechanism

34 lever

35 connecting part

41 separation frame

42 fastener

43 fixing element

51 bottom panel

52 side panel

53 backplate

61 moving coil

62 magnetic circuit

81 Circuit Board

321 extension part

331 beam

331 flexible part

341 fixed part

Claims

1. An electronic balance is characterized by comprising:

a weighing pan on which an object to be measured is placed;

a block-shaped mechanism body formed by digging through a base material and provided with the weighing pan;

a 1 st frame fixed to the block mechanism body by a plurality of fixing members;

a 2 nd frame fixed to the 1 st frame;

an electromagnetic force generating device mounted on the 1 st frame or the 2 nd frame;

a base member supporting the 2 nd frame in the vicinity of a lower side of the electromagnetic force generating device,

at the block mechanism body, integrally formed are: a movable column mounting the weighing pan; the fixed column is fixed with the 1 st frame; a Roebville mechanism that couples the movable column and the fixed column and restricts displacement of the weighing pan in a vertical direction,

an elongated extension portion that extends along the roberval mechanism to the movable column side and is fixed to the 1 st frame by the fixing member at least at the end portion of the extension portion on the movable column side is formed on the fixed column,

the electromagnetic force generating device is arranged adjacent to the fixed column,

the 2 nd frame supports the 1 st frame from below in a range from below the electromagnetic force generating device to below the fixing member fixed to the movable-column-side end of the extension portion.

2. The electronic balance according to claim 1,

the 1 st frame includes a pair of split frames that sandwich the block-shaped mechanism body in a width direction orthogonal to a longitudinal direction of the extension portion and are fixed to the extension portion by the fixing members,

the pair of separation frames are fixed to the 2 nd frame, respectively.

3. The electronic balance according to claim 2,

the electromagnetic force generating device is mounted to the 2 nd frame.