JPH04294220A - Mechanism for adding/removing internal weight of scale - Google Patents

Abstract

PURPOSE:To quickly, correctly and automatically attach or detach an internal weight to a weighing mechanism. CONSTITUTION:A plurality of associative elements 31a... are mounted to a supporting body 32 in a swinging fashion. Each swing plate is provided with a pair of weight suspending tools 30a1.... Moreover, each associative element is provided with a push rod 36a which has a start motor 34 via a motion converting mechanism 35. The rotation of the motor 34 is transmitted as the back-and-forth movement in the X2-Y2 direction to the push rod via the motion converting mechanism 35, so that the associative elements 31a... swing in the X3-Y3 direction. As a result, the weight suspending tools 30a1... rising and falling in association with the swing of true associative elements 31a attach/ detach ring-shaped internal weights 50 to/from an arm 40 of a weighing mechanism 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight adding/removing mechanism built into a scale, and more particularly to a weight adding/removing mechanism suitable for electronic scales.

[0002] Even in electronic scales such as electromagnetic balance type electronic balances, weights are necessary for evacuation of air during measurement, calibration of the scale, and the like. For this reason, electronic scales have been proposed and put into practical use, in which these weights are stored in the scale, and the above operations are performed using predetermined weights either by the user's operation or by automatic operation of the scale. .

In addition, in an electromagnetic balance type scale, when weighing, a built-in weight corresponding to the weight of the object to be weighed is added to the weight measuring mechanism, or conversely, the added weight is removed.
When measuring weight, a method is sometimes used to avoid exceeding the electromagnetic equilibrium range of the scale. In this way, the electromagnetic weighing range of the scale is, for example, 200.
By appropriately adding or subtracting the internal weight while setting the weight as small as mg, the weighing capacity of the scale can be set as large as, for example, 3 g. As mentioned above, the weight used to partially replace the weight of the object to be weighed will be hereinafter referred to as a "replacement weight" in order to distinguish it from a calibration weight or a weight for weight measurement. Note that, depending on the method of operating the weight, it is possible to use a calibration weight or a wind weight as a replacement weight.

0004

[Problem to be solved by the invention] When the accuracy of the scale is high and the electromagnetic weighing range is set small,
Naturally, the range in which the weight of the weighed object should be replaced by the replacement weight is wide, and therefore it is necessary to store a large number of weights with different weights and to appropriately select and use one or more of these weights. As a result, the operation of adding and removing weights to and from the weight measuring mechanism becomes quite complicated.

FIG. 9 conceptually shows a conventional example of a displacement weight adjustment mechanism.

A weight 51 is secured to one end of a rod 60 that swings about a fulcrum 53, and a cam 52 is arranged so as to be in contact with the rod 60, thereby forming a weight addition/removal mechanism. Such weight adding/removing mechanisms are arranged in a number corresponding to the number of built-in weights 51, and the cam of each mechanism is attached to one shaft 61. By rotating this shaft 61 and adjusting the rotation angle appropriately, a predetermined weight can be added or removed. The rotation of the shaft 61 can be performed manually, for example, by directly operating an operating end (often dial-shaped) attached to the weighing device, or automatically or semi-automatically through a drive mechanism such as a motor. It is about to be done. An example of a mechanism using such a cam is Utility Model Publication No. 57-13454.

However, when selecting an unknown weight for balancing, the shaft must be rotated in sequence, which increases the number of operations, and manual operation places a heavy burden on the operator. There are also other problems, such as the possibility of failure due to malfunction of the cam. For this reason, an automated version of the above configuration has been proposed, which frees the operator from complicated cam operations, but there is a limit to the reduction in operating time.

Next, FIG. 10 shows an improved version of the above configuration, in which the rod 60 is swung using a solenoid 54. In this way, each mechanism can be operated independently using the solenoid of each weight adjustment/removal mechanism, thereby increasing the number of combinations of weights that can be used.

However, the solenoid 54 is electromagnetically turned on.
Due to the off operation, the weight locking part moves up and down rapidly due to the rocking of the rod 60 by this solenoid, and the weight 51
When the weight is added or removed, the locked weight 51 shakes and vibrations are transmitted to the weighing mechanism, making it impossible to measure until the shaking and vibrations subside, and eventually the device stabilizes and begins measurement. It will take time to do so.

0010

[Means for Solving the Problems] The present invention has been constructed in view of the above-mentioned problems, and provides a weight addition/removal mechanism that can automate the operation, shorten the operation time, and reduce the occurrence of failures. It is characterized by

That is, in the present invention, a pair of weight lifting tools are provided for each of the plurality of response pieces located in parallel, and ring-shaped weights are respectively locked to the weight lifting tools. Further, a drive mechanism for causing the response piece to swing is disposed on the response piece.

0012

[Operation] The pressing means such as a push rod presses the response piece by operating a drive device such as a motor, thereby rotating the response piece by a certain angle. Through this rotational movement, a predetermined weight among the weights previously locked on the weighing mechanism side is locked on the weight lifting tool side connected to the response piece, or vice versa. Lock the weight that was placed on the weighing mechanism side.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, before explaining the details of the structure of the present invention, an outline of the structure of an electronic scale, which is one of the objects of the present invention, will be explained.

FIG. 8 schematically shows the structure of an automatic electronic weighing scale that has been previously filed by the applicant.

Arrow 1 is an electromagnetic balance type electronic balance (electronic balance)
The main body, 2, is an internal weighing chamber disposed within the weighing chamber 3 of this electronic balance main body, 4 is a weighing plate loading/unloading mechanism, 6, for loading and unloading the weighing plate 5 and locking the weighing plate 5 to a weight measuring mechanism, which will be described later. is a door opening/closing mechanism that opens and closes the door of the internal weighing chamber 2 in cooperation with the weighing plate loading/unloading mechanism 4.

Next, reference numeral 7 indicates a weight adding/removing device according to the present invention, which is disposed above the weighing plate loading/unloading mechanism 4. An arrow 8 indicates an electromagnetic balance type weighing mechanism that measures the weight of the sample placed on the weighing pan 5. Further, reference numeral 9 is an outer door for opening and closing the weighing chamber 3, and 10 is an electric circuit section for feedback controlling the electromagnetic section 11 and processing measurement results.
It is installed away from the device main body 1 in consideration of heat generation from the circuit portion.

In the weighing device configured as described above, when measuring the weight of a sample, first the weighing plate 5 on which the sample is placed is stored in the internal weighing chamber 2 of the weighing chamber 3 by the weighing plate loading/unloading mechanism 4, and then the door opening/closing mechanism 6 closes the door of the internal weighing chamber 2. In this state, the weighing plate 5 is locked to the weighing mechanism 8 by the weighing plate loading/unloading mechanism 4 . Furthermore, based on the rough weight of the sample measured by the weighing mechanism 8 through this locking operation, the weight addition/removal device 7 is activated to transfer a predetermined weight from among the weights previously locked to the weighing mechanism side to the weight addition/removal device side. to lock. In this state, the weight of the sample is measured, and the measurement result is sent to the electric circuit section 10.
The configuration is such that the data is processed and displayed at the .

Next, an embodiment of the present invention will be explained using mainly FIGS. 1 to 3.

Note that the weights to be operated by the weight addition/removal device are not limited to the above-mentioned replacement weights, but can also be used as calibration weights or air pull weights. We will refer to it as "weight".

The weight adding/removing device 7 consists of a weight locking portion for directly locking and supporting the internal weight, and an operating portion for operating this weight locking portion.

First, the structure of the internal weight and the part that locks the internal weight will be explained. First, a weight addition/removal device 7 according to the present invention is installed on a partition plate 29 located above the weighing plate loading/unloading mechanism 4.

Reference numerals 30a1 and 30a2 in the figure are weight lifting tools for suspending and supporting the ring-shaped internal weight 50. The tip of this weight lifting tool has weight locking parts 30a1' and 30a2 which are bent into a substantially U-shape from the front.
', and each ring-shaped internal weight 50 is suspended and supported by this U-shaped valley. Also, the side walls of these weight locking portions 30a1' and 30a2' are cut out to form release portions 30a1'' and 30a2''.
are formed respectively.

[0023] Here, an arm 40 of a load transmitting member forming a part of a weighing mechanism to be described later is inserted into the internal weight 50 so as to be perpendicular to the internal weight 50.
By forming 1″ and 30a2″,
The internal weight lifting tools 30a1 and 30a2 can be raised and lowered without being hindered by the arm 40 of the load transmission member.

Next, 31a refers to these weight lifting tools 30a1.
and 30a2 are attached to the response piece. Reference numeral 32 denotes a support body fixed to the partition plate 29, and the response piece 31a is connected to the support body 32 by flexible support plates (flexible support plates) 33a and 33 made of plate springs or the like.
It is swingably suspended and supported by using b as a hinge. Further, the weight lifting tools 30a1 and 30a2 are fixed at the flexible support plates 33a, 33b mounting portions so as to be substantially orthogonal to the response piece 31a. As a result, the weight lifting tools 30a1 and 30a2 form a pair by the response piece 31a, and the support plates 33a, 33
By operating b as a hinge, the response piece 31a swings to move up and down.

[0025] In this way, a plurality of pairs of weight lifting tools are arranged using a plurality of response pieces, and each pair of weight lifting tools is moved up and down as appropriate by a drive mechanism to be described later.

FIG. 3 shows the arrangement of such a weight lifting tool.

In the illustrated configuration, five pairs of weight lifting tools are arranged, and in addition to the weight lifting tools 30a1 and 30a2 described above, weight lifting tools 30b1 and 30b2 are paired by a response piece 31b in order from the inside part. , weight lifting tools 30c1 and 30c2 that form a pair by the response piece 31c,
A pair of weight lifting tools 30d1 and 30d2 are arranged by the response piece 31d, and a pair of weight lifting tools 30a1 and 30a2 are arranged by the above-mentioned response piece 31a. Moving weight lifting tools 30e and 30f are arranged. In addition, in the illustrated configuration, the outermost weight lifting tool 3
Only the sets 0e and 30f have response pieces 31e and 31f.
are independent and are configured to operate independently, but it is of course possible to configure these sets to operate integrally.

Next, the drive mechanism of the weight lifting tool will be explained mainly with reference to FIGS. 1 and 7.

In FIG. 1, 34a is a motor, 35 is a motion conversion mechanism connected to the rotating shaft of this motor 34a, and 36a is a motor.
is a push rod connected to this motion conversion mechanism 35. The motion conversion mechanism 35 has a function of converting the rotation of the motor 34a into a motion in the X2-Y2 direction, which is the direction of the axis of rotation, and transmitting the motion to the push rod 36a. This motion conversion mechanism 35 may be any mechanism as long as it can move the push rod 36a in the X2-Y2 direction, such as a combination of a worm and a worm rack that engages with the worm. It's not something to ask. Furthermore, configurations other than the combination of the motor 34a and the motion conversion mechanism 35 as shown in the figure, such as a mechanism using an air cylinder that performs linear motion, or a mechanism in which the push rod is directly actuated by an electromagnetic mechanism, may be used. It's okay.

51 is the push rod 36a
- It is a support body that supports while allowing operation in the Y2 direction. The tip of this push rod 36a is inserted into the weight lifting tools 30a1 and 30 through the insertion hole of the support plate 32.
It is located in contact with the back surface of the response piece 31a to which a2 is attached.

The drive mechanism described above, the response piece 31a, and the weight lifting tool 30a attached to the response piece 31a.
One internal weight lifting device unit is formed by the set of 1 30a2, and the integral internal weight locking mechanism 7 is formed by a plurality of similarly formed weight lifting device units. That is, the response pieces 31 of each pair of weight lifting tools including FIG.
Push rods 36b, 36c, 36d, and 36e are operated in the X2-Y2 direction by motors similar to those described above for push rods 36b, 31c, 31d, 31e, and 31f, respectively.
, 31f respectively form an internal weight suspension unit. By the operation of the push rods in each of these units, each pair of internal weight lifting tools is made to swing about the support plates 33a, 33b, . . . , respectively. Note that reference numerals 34a to 34f are motors for driving the push rods 36a to 36f.

Next, the weighing mechanism to which the internal weight is added and removed will be explained with reference to FIGS. 4 to 6, focusing on the load transmission member.

In FIG. 4, arrow 37 indicates a load transmitting member. This load transmission member 37 is connected to the beam 39 of the weighing mechanism, which forms the central mechanism of the electronic balance, via a connecting member shown by an arrow 38.
is connected to.

First, the arrangement of the load transmitting member 37 and the beam 39 of the weighing mechanism will be explained, and then the arrangement of the weight addition/removal device will be explained.

As shown in FIGS. 4 and 5, the load transmitting member 37 is formed into a substantially cross shape when viewed from the front, and its lower end is connected to an internal weighing device located at the bottom of the partition plate through an opening formed in the partition plate 29. A hook 55 is located in the chamber 2 and hangs the weighing plate 5. A pair of internal weight locking arms (hereinafter simply referred to as "arms") 40, 40 are located above the hook 55 and extend symmetrically with respect to the horizontal direction.

On the other hand, the connecting member 38 includes a beam-side connecting portion 41 having a substantially V-shaped side surface, and a load-transmitting member-side connecting portion connected to the beam-side connecting portion 41 so as to be perpendicular to the beam-side connecting portion 41. It consists of 42. Furthermore, this load transmitting member side connecting portion 42 is composed of an upper plate 42a that is directly connected to the beam side connecting portion 41, and a lower plate 42b that is connected to this upper plate 42a via an intervening member 42'. A slit 42b' is formed along the longitudinal direction of the lower plate 42b (see FIG. 6). Further, a support wire 43 is stretched over this slit 42b'. The load transmission member 37 directly connects to this support wire 43.
The structure is such that it is suspended and supported. The reason why the load transmitting member 37 is suspended and supported by support wires, which will be described later, including this support wire 43, is to improve the accuracy of the weighing mechanism by maintaining the position of the point of force relative to the beam 39 accurately. It is. In addition, the support wire 4
3 is suitably made of platinum (Pt) wire including the support wire described later.

On the other hand, the connecting member 38 is connected to the beam side connecting member 41.
It is connected to the beam 39 of the weighing mechanism 8 by means of support wires 44a and 44b stretched in a cross shape. The beam 39 itself is also supported by a similar support wire 45, and is configured to transmit the load of the sample to the electromagnetic section 46 using the support wire 45 as a fulcrum. Next, the arrangement of the load transmitting member 37 and the weight adding/removing device 7 will be explained. In FIGS. 2 and 3 described above, the load transmission member 37 is located at the center of the five pairs of weight lifting tools 30a1 to 30f, and the arms 40, 40 extended symmetrically are connected to each of these weight lifting tools 30a1 to 30f. 30f weight locking part 30a
1'... Opening portions 3 formed in these weight locking portions so as to be orthogonal to the ring-shaped internal weights 50 located within.
0a1''..., and the weights 50 located at each weight locking portion are locked to these arms 40, 40. Among the internal weights 50, the pair of weight lifting By setting the weights of the respective weights on the tools to be the same, the weights to be added to both arms 40 are made to be the same on the left and right sides.

Next, the operation of the weight adding/removing device 7 will be explained using the electronic balance as an example.

First, each pair of weight lifting tools is normally suspended and supported in the vertical direction by the support plate 32 via each flexible support plate 33a, 33b, and so on. The internal weights 50 disposed in the weight locking portions of the tool are all locked to the arms 40, 40 of the load transmitting member inserted through the open portions of these weight locking portions. Next, the weighing plate 5 on which the sample is placed is drawn into the internal weighing chamber 2 by the operation of the weighing plate loading/unloading mechanism 4 as described above, and is hooked onto the hook 55 of the load transmitting member 37.

[0040] The load of the sample is thereby transferred to the load transmission member 3.
7 to the weighing mechanism 8, and the weighing mechanism 8 first measures the rough weight (rough weight) of this sample, and sets the load to be added to the weighing mechanism, that is, the replacement weight, in accordance with this rough weight. , select an internal weight of weight that approximates this replacement weight, and remove the other weights from the arms 40, 40, leaving the selected internal weight behind. More specifically, for example, what corresponds to this replacement weight is the above-mentioned internal weight lifting tool 30.
If the weight is the total weight of the other internal weight lifting tools excluding a1 and 30a2, the motor 34a is activated to move the push rod 36a in the X2 direction (see FIG. 1). By the operation of this push rod 36a, the support plate 32
The response piece 31a was suspended and supported in the vertical direction by
rotates in the X3 direction using the flexible support plates 33a and 33b as hinges. The internal weights 50, which were locked to the arms 40 and 40 by the weight lifting tools 30a1 and 30a2, which rotate in the X3 direction together with the response piece 31a, are locked to the weight lifting tools 30a1 and 30a2, and these weights 5
0.50 weight is removed from arm 40. Therefore, the weight of the remaining internal weight is added to the weighing mechanism as a replacement weight when measuring the sample. If another combination of internal weights is required, change the push rod 36a to Y2.
By returning the weight lifting tools 30a1 and 30 to the
The internal weights that were locked on a2 are returned to the arms 40, 40, and then the appropriate pushrods are actuated to remove the appropriate weights. In this case, the flexible support plates 33a of each response piece are made of an elastic material such as a plate spring, so that when the push rod is pulled back in the Y2 direction, the elasticity of the flexible support plates Due to the restoring force, the response piece reliably returns to the predetermined position in the Y3 direction, and the reliability of the device operation can be guaranteed. Furthermore, by installing a position sensor consisting of an optical sensor and a shielding plate on this response piece, the operation information of the response piece can be inputted to the control section of the device, thereby making the operation more reliable. It is possible.

As described above, it is possible to select an appropriate replacement weight by appropriately adding or subtracting each internal weight.

The operation of the above mechanism is achieved by the movement of the push rod in the X2-Y direction and the swinging of each response piece in the X3-Y3 direction accompanying this movement. The push rod operates very smoothly, and no sudden shock or vibration is applied to the response piece when the push rod is operated. Therefore, the internal weight does not shake or vibrate when the internal weight is replaced, and the weighing mechanism immediately stabilizes after the internal weight is replaced, allowing the measurement work to be completed in a short time.

The beam 39 of the weighing mechanism and the load transmitting member 37 are connected by a support wire, and in particular, the lower plate 42b of the load transmitting member side connecting portion 42 of the connecting member 38 and the load transmitting member 37 are connected by a support wire. 43, there is no displacement of the point of force on the beam 39, which is the balance, and this greatly contributes to maintaining high measurement accuracy.

[0044] Above, we have explained the case where the internal weight to be replaced is used as a replacement weight in the measurement of the weight of a sample, but in addition to this, it can also be used as a calibration weight when calibrating a weighing mechanism, or as a weight for drawing air. It can also be used as a weight. For example, if an internal weight placed on a weight lifting tool 30e attached to an independently swinging response piece 31e is used as a calibration weight, the weight can be suspended by always positioning the response piece 31e in the X3 direction. It is locked to the upper tool side 30e, and only when performing calibration, it is rotated in the Y3 direction and locked to the arm 40. On the other hand, all other weight lifting tools are rotated in the X3 direction and operated so as to be locked to the weight lifting tool side, and only the weight of the weight lifting tool 30e is added to the weighing mechanism to perform calibration. conduct.

[Effects] As specifically explained above, the present invention allows ring-shaped weights to be respectively locked to weight lifting tools provided for a plurality of response pieces located in the vertical direction. Furthermore, a mechanism for swinging the response piece is arranged for this response piece, and there is no complicated cam operation, etc., simplifying the configuration and greatly increasing the reliability of the device. improves.

[0046] Also, compared to the conventional cam configuration, the operation is faster, and compared to the one using a solenoid, there is almost no vibration or impact on the weighing mechanism when changing weights, so the weighing mechanism can be used in a short time. It is stable and allows for quick measurement work.

[Brief explanation of the drawing]

FIG. 1 is a side view of an internal weight adding/removing device.

FIG. 2 is a perspective view showing the arrangement of a response piece and a weight lifting tool that form part of the internal weight addition/removal device.

FIG. 3 is a front view of the response piece and weight lifting tool shown in FIG. 2;

FIG. 4 is a front view of the load transmission member.

FIG. 5 is a perspective view of the load transfer member and beam.

FIG. 6 is a bottom view of a connecting member forming part of the load transmitting member.

FIG. 7 is a plan view of the internal weight addition/removal device.

FIG. 8 is a schematic cross-sectional view of an electronic balance equipped with an internal weight addition/removal device according to the present invention.

FIG. 9 is a schematic diagram of a conventional device using a cam.

FIG. 10 is a schematic diagram of a conventional device using a solenoid.

[Explanation of symbols]

1 Electronic balance main body 7 Internal weight addition/removal device 8 Weighing mechanism 30a1 to 30d2 Weight lifting tool 30a1',
30a2 ′ Weight locking part 30a1 ″, 30a2
'' Opening part 30e of weight locking part 30e Weight lifting tool 30f Weight lifting tool 31a to 31f Response piece 32 Support bodies 33a to 33b Flexible support plates 34a to 34f Motor 35 Movement conversion mechanism 36a to 36f Push rod 37 Load transmission Member 38 Connection member 39 Beam 40 Arm 50 (of the load transmission member) Internal weight

Claims (3)

[Claims] 1. Selecting an internal weight that balances the load to be measured from among internal weights of different weights that are locked to an arm of a load transmission member that forms part of a weighing mechanism, and removing the remaining internal weights from the arm. a plurality of weight lifting tools for lifting each internal weight from the arm, a support body for supporting these weight lifting tools so that they can move up and down individually, and each integrally provided with each weight lifting tool. A scale characterized in that it comprises: response pieces that are attached to the scale, and a drive means that contacts these response pieces and presses the response pieces to cause the weight lifting tool to move up and down via the response pieces. Internal weight adjustment mechanism. 2. The driving means includes a motor disposed outside the scale case, a motion conversion mechanism that converts rotational motion of the motor into linear motion, and a motion conversion mechanism connected to the motion conversion mechanism that moves back and forth with respect to the response piece. 2. The internal weight addition/removal mechanism for a scale according to claim 1, further comprising a push rod that pushes the response piece when moved. 3. The responsive piece is supported by a support body through an elastic plate, and the responsive piece is configured to move in an arc around the elastic plate by actuation of a driving means. An internal weight addition/removal mechanism for a scale according to claim 1 or 2.