JP2002107216A - Electronic force balance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a spring part of a Roberval mechanism or a moving portion of a lever. SOLUTION: The Roberval mechanism is formed by installing a pair of Roberval parts 18 having the specified length between a fixed part 12 and a moving part 14 through a thin spring part 20, the fixed part 12 of the Roberval mechanism 2 is fixed to a base plate 10 to movably support the moving part 14. A stopper 23 for regulating a moving range of the moving part 14 is installed between the moving part 14 of the Roberval mechanism 2 and the base plate 10. During use, even if goods suddenly fall down on the moving part 14 side, since the stopper 23 regulates the moving range of the moving part 14 to prevent unnecessary movement of the moving part 14, a shock load applied to the spring part 20 of the Roberval mechanism 2 or the moving portions (spring parts 34, 36) of the lever 4 is prevented to protect them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic balance for measuring the mass of an object to be weighed, and more particularly to an electronic balance capable of protecting a roberval mechanism and a lever by restricting a movable range of a roberval mechanism constituting an electronic balance. .

[0002]

2. Description of the Related Art FIG. 12 shows a conventional electronic balance (Japanese Patent Publication No.
FIG. 13 is a front sectional view showing the same, and FIG. 13 is a perspective view of the same. Another example is disclosed in Japanese Patent Application Laid-Open No. 11-51756. In these electronic balances 80, a movable portion 81b provided with a mounting plate 90 is provided with a base frame 92.
A roberval mechanism 81 movable with respect to a fixed portion 81a fixed to the support 92a of the first and second members, a lever 83 linked with the movement of the movable portion 81b, an electromagnetic coil 85 for controlling movement of the lever 83 so as to be in an equilibrium state, And a control unit (not shown) for controlling the energization of the electromagnetic coil 85 to calculate and output the mass of the object to be weighed.

As shown in the figure, the roberval mechanism 81 has a pair of upper and lower parallel roberval portions 86 formed by cutting aluminum or the like in the shape of a rectangular parallelepiped from the side. A total of four thin spring portions 87 are formed in the roberval portion 86. When an object to be weighed is placed on the placing plate 90 of the movable portion 81b, the spring portion 87 is deformed by receiving this load. Then, the movable portion 81b moves downward while maintaining the horizontal state.

In conjunction with this, the free end 83b of the lever 83 is displaced upward from the equilibrium position. The control unit controls the energization of the electromagnetic coil 85 based on the output of the position detection sensor so that the lever 83 is in an equilibrium state, and calculates the mass of the object to be weighed based on the current value to the electromagnetic coil 85 when the lever 83 is in equilibrium. Calculation output.

The lever 83 in the configuration shown in the figure is
While the other electronic balance (Japanese Patent Laid-Open No. 11-51756) is formed separately from the above-mentioned electronic balance, it is different from the one formed integrally with the roberval mechanism 81. 81 is formed by hollowing out the above-mentioned integral lump.

[0006] Such a roberval mechanism 81 is formed with a predetermined measurement range of the mass of the object to be weighed. In particular, the rigidity of the entire roberval mechanism 81 and the spring constant of the spring portion 87 are suitable for this measurement. It is set appropriately. The stiffness of the roberval mechanism 81 and the spring constant of the spring portion 87 affect the time (response time) from the start of measurement, that is, the convergence of the vibration of the movable portion 81b from when the object to be weighed is placed on until it can be measured. .

[0007]

However, in the above-described conventional electronic balance 80, the roberval mechanism 81 is formed by cutting out rectangular aluminum or the like from the side to form a thin spring portion 87 having a total of four points. Configuration. For this reason, in use (when measuring the mass of the object to be weighed), if there is an unexpected fallen object on the placing plate 90 and an impact load is applied to the spring portion 87 via the movable portion 81b, the roberval mechanism is used. There is a problem that the spring portion 87 of 81 and the movable portion (for example, a fulcrum portion) of the lever 83 are damaged.

In view of the above, an object of the present invention is to provide an electronic balance capable of restricting a movable range of a roberval mechanism to protect a spring portion and a movable portion of a lever of the roberval mechanism. And

[0009]

According to the first aspect of the present invention, there is provided an electronic balance, comprising:
A pair of roberval portions 18 having a predetermined length is provided between the movable portion 14 and the movable portion 14 via a thin spring portion 20, and the movable portion 14 receiving the load of the object to be weighed is moved in a horizontal state. A roberval mechanism 2 to be fixed, a base plate 10 for fixing the fixed portion 12 of the roberval mechanism 2 and movably supporting the movable portion 14, and between the movable portion 14 of the roberval mechanism 2 and the base plate 10. A stopper 4 that regulates the range of movement of the movable part 14, the lever 4 whose free end 4 b is displaced by a predetermined amount from an equilibrium state by interlocking with the movement of the movable part 14, Equilibrium drive means 6 for controlling the movement of the lever 4 to be in an equilibrium state in order to calculate and output the mass.

In the electronic balance according to the second aspect, the fixing portion 12
A pair of roberval portions 18 having a predetermined length is provided between the movable portion 14 and the movable portion 14 via a thin spring portion 20, and the movable portion 14 receiving the load of the object to be weighed is moved in a horizontal state. A roberval mechanism 2 to be fixed, a base plate 10 for fixing the fixed part 12 of the roberval mechanism 2 and movably supporting the movable part 14, and a load receiving member 42 attached to the movable part 14 of the roberval mechanism 2. A stopper 23 that is provided between the movable member 14 and the base plate 10 and regulates a moving range of the movable member 14. It is characterized by comprising a lever 4 and equilibrium driving means 6 for controlling the movement of the lever 4 to be in an equilibrium state in order to calculate and output the mass of the object to be weighed.

According to a third aspect of the present invention, there is provided the electronic balance according to the first or second aspect, wherein the stopper is configured to adjust a moving range of the movable portion of the roberval mechanism. It is characterized by being.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of the electronic balance. The electronic balance 1 includes a roberval mechanism 2, a lever 4, an equilibrium drive unit 6 including an electromagnetic coil for controlling the lever 4 to be in an equilibrium state, a position detection unit (not shown), and a control unit (not shown). Do it.

A load receiving member (described later) is fixed on the movable portion 14 of the roberval mechanism 2, and a dynamic balance in which a conveyor is mounted on the load receiving member can be constructed. Then, the mass of the object is measured while the object is conveyed by the conveyor. In addition, it is also possible to provide a placing plate on the movable portion 14 and use the object to be weighed on the placing plate as a static balance for measuring the mass.

FIG. 2 is a front view showing the roberval mechanism 2.
3 is a plan view, FIG. 4 is a right side view, and FIG. 5 is a left side view. The roberval mechanism 2 includes a fixed part 12 and a fixed part 1.
2 has a movable portion 14 that can move up and down. The upper surface of the movable part 14 is formed slightly higher than the fixed part 12. The roberval mechanism 2 is formed by hollowing out a single piece of material such as a rectangular parallelepiped aluminum piece having a length L1 and a width W1 from the front side and penetrating the hollow portion 16 therein. Also,
This roberval mechanism 2 is formed by extrusion molding or the like.
May be formed. At this time, a pair of parallel roberval portions 18 having a predetermined thickness are provided above and below. The pair of roberval portions 18 have the same length in the length direction L1, and thin spring portions 20 are formed at both ends. The spring portions 20 are provided at two locations on the upper and lower surfaces, for a total of four locations. Each of the spring portions 20 has an arc shape when viewed from the upper and lower surfaces, and is formed in a linear shape that is continuous in the width W1 direction.

At a position directly below the upper roberval portion 18,
A lever fixing portion 22 for fixing the lever 4 is formed in parallel with the roberval portion 18. The lever fixing part 22 is composed of the fixing part 12 of the roberval part 18 and the movable part 14.
Has a cutting portion 22s in the middle of the length L direction corresponding to
There is a gap that does not hinder the movement of the movable part 14 with respect to the fixed part 12. By this cutting, the lever fixing part 22
It has a fixed side 22a and a movable side 22b.

A stopper 23 is provided on the lower surface of the movable section 14. The stopper 23 is connected to the movable portion 14
23a screwed to the lower surface of the
And a leg 23b formed integrally with the lower end of the arm. When the screw portion 23a rotates, the stopper 23
Can be adjusted so as to move toward and away from the lower surface of the movable portion 14.

A protruding piece 24 having a predetermined length is formed on an upper end of the one end 2a in the length direction L1 of the roberval mechanism 2 and an equilibrium driving means 6 is mounted on a lower surface thereof. The roberval mechanism 2 located at the one end 2a
The lever housing portion 2b having a substantially rectangular parallelepiped shape is hollowed out from the center of one side surface toward the inside of the roberval mechanism 2.
Are formed. The lever accommodating portion 2b is formed on the lower surface of the lever fixing portion 22, and has a hollow portion 1b.
6, and is hollowed out to a position on the movable portion 14 side (until reaching a position beyond the spring portion 20 of the roberval portion 18) when viewed from the front side in FIG.

FIG. 6 is a front view of the lever 4, FIG. 7 is a plan view thereof, and FIG. 8 is a side view thereof. The lever 4 has a width W2 smaller than the width W1 of the roberval mechanism 2 and is reduced in size and weight. The fixed portion 12 (fixed side 22a) of the roberval portion 18 and the movable portion 14 are provided on the base 4a side of the lever 4.
The fixed part 30 and the movable part 32a which are respectively fixed to (the movable side 22b) are formed. The other end is a free end 4b
The free end 4b extends to an external position of the roberval mechanism 2 after the lever 4 is fixed to the roberval mechanism 2, and is located immediately below the protruding piece 24.

The lever 4 is a movable part 1 of the roberval mechanism 2.
The movable portion 32a moves in conjunction with the movement of 4, and the free end 4b moves up and down. The lever 4 in the present embodiment has two fulcrums A and B, and the mass (load load) of the object to be measured applied to the movable part 14 is attenuated by a predetermined amount by the two fulcrums A and B. The function of the lever 4 and the length L2 of the lever 4 are reduced.

A specific configuration of the lever 4 will be described. The lever 4 is formed by cutting out a lump of a single material such as an aluminum lump like the roberval mechanism 2. At this time, as shown in FIG. 6, the cutting portion 28 (2
8a, 28b, 28c) are formed through. The fixed portion 30 is provided substantially at the center by the cutting portion 28, and the movable portions 32 (32a, 32b, 32
c) is formed.

The fixed portion 30 and the movable portion 32 of the lever 4 are connected to each other by two thin spring portions 34 located at the fulcrums A and B by forming the cutting portion 28. The spring portion 34 is formed in substantially the same shape as the spring portion 20 of the roberval mechanism 2, and the description is omitted.

The lever 4 in the present embodiment applies a load applied to the movable end 32 to the base end 4 a by a spring portion 34.
In order to efficiently transmit to the free end 4b side via the fulcrums A and B at the same time, and to maintain the strength of the spring portion 34, a plurality of spring portions 36 are provided at necessary places (a total of three places) similarly to the spring portions 34. Is formed. This spring portion 36 is also formed in substantially the same shape as the spring portion 20 of the roberval mechanism 2,
Description is omitted.

FIG. 9 is a partially cut front view showing an assembled state of the electronic balance. In this drawing, for convenience, the lever 4 is not cut, and only the robarbal mechanism 2 is cut. The electronic balance 1 is configured by inserting and fixing a lever 4 inside the roberval mechanism 2. In the roberval mechanism 2, the lower surface of the fixing part 12 is fixed on the base plate 10 with screws 11. Thereby, the movable portion 14 of the roberval mechanism 2 is movably supported with respect to the base plate 10. At this time, the stopper 23 attached to the lower surface position of the movable portion 14 forms a predetermined interval t between the leg portion 23b and the upper surface of the base plate 10. This interval t is equal to the length of the screw portion 23a of the stopper 23.
Can be adjusted by rotating.

Further, the lever housing 2 of the roberval mechanism 2
The lever 4 is inserted into “b”, and the proximal end 4 a is fixed to the lever fixing portion 22 with the screw 25. A step portion 22d for guiding one side surface of the lever 4 along the length direction L1 is formed on the lower surface of the lever fixing portion 22 forming the lever housing portion 2b. Thereby, positioning at the time of insertion of the lever 4 can be easily performed and assembly can be easily performed.

The fixed portion 30 of the lever 4 is fixed to the fixed side 22a of the lever fixed portion 22, and the movable portion 32 of the lever 4 is fixed to the movable side 22b of the lever fixed portion 22.
In this fixed state, the free end 4 b of the lever 4 protrudes from the one end 2 a of the roberval mechanism 2 and is located immediately below the protruding piece 24. As described above, by providing the lever 4 inside the roberval mechanism 2, the overall size can be reduced.

On the free end 4b side of the lever 4, a weight mounting piece 3
8 is formed so as to protrude downward, and a substantially horizontal screw hole 38b is formed.
The balance weight 40 is attached to the part so as to be slidable in the horizontal direction. Thereby, the movable part 14 of the roberval mechanism 2
When the load receiving member or the like receives a heavy load,
Adjustment of 0 allows the lever 4 to be balanced. In addition,
The equilibrium state of the lever 4 is detected by a slit provided at the free end 4b and a position detection sensor (not shown) fixed to the protruding piece 24 side, and the moving direction of the lever 4 is also detected. I have.

The electromagnetic coils constituting the balance driving means 6 are as follows:
An annular magnet 6a is fixed to the lower surface of the protruding piece 24, and a wound coil 6b is fixed to the inside of the ring of the magnet 6a on the upper surface of the free end 4b of the lever 4. As described above, since the electromagnetic coil can be provided outside the roberval mechanism 2, assembly and maintenance during manufacturing can be easily performed. The equilibrium drive unit 6 receives current control of the control unit when measuring the object to be weighed, changes the magnetic force between the magnet 6a and the current supplied to the coil 6b, and returns the lever 4 to the equilibrium state.

Hereinafter, the operation of measuring the mass of an object to be weighed by the electronic balance 1 having the above configuration will be described. By adjusting the balance weight 40, the lever 4 is balanced in the state where the load receiving member (including the conveyor weight) is under a heavy load. The equilibrium state of the lever 4 is detected by a position detection sensor.

Next, the object to be weighed is placed on a conveyor placed on a load receiving member as a dynamic balance, and is conveyed and moved on this conveyor. In the roberval mechanism 2, the movable portion 14 descends in the Z1 direction in FIG. At this time, the roberval section 18 lowers the movable section 14 while maintaining the horizontal state by the deformation of the spring sections 20 at a total of four places.

In conjunction with the lowering of the movable section 14, the movable section 32 of the lever 4 similarly moves down. When the movable portion 32a descends, the movable portion 32b moves in the Z2 direction in FIG. 9 around the spring portion 34 (fulcrum A), and the free end 4b (movable portion 32c) of the lever 4 moves to the spring portion 34 (fulcrum B). It rises in the Z3 direction in FIG. 9 as the center.

The free end 4b of the lever 4 is displaced (rises) by a predetermined amount with respect to the equilibrium state, and this displacement is detected by a position detecting sensor. The control section controls the energization of the electromagnetic coil of the balancing means 6 so that the lever 4 returns to the balanced state again. At this time, the current direction of the electromagnetic coil to the coil 6b and the amount of current to be supplied are controlled, and the lever 4 is detected by the position detection sensor.
Obtains a current value to the electromagnetic coil 6b when it is detected that the balance has reached the equilibrium state again, and calculates and outputs the mass of the object to be weighed based on this current value.

As described above, the fulcrum of the lever 4 is set at two points A,
By providing B, the mass (load load) of the object to be weighed applied to the movable portion 32 can be attenuated and transmitted to the free end 4b side, and at the same time, the displacement of the free end 4b side with respect to the movement amount of the movable portion 32 side It can be obtained in increasing amounts. This allows
The weighing accuracy can be improved. Further, the length of the lever 4 in the direction of the length L2 can be shortened, and a configuration having a predetermined amount of attenuation can be achieved. Further, since the lever 4 is reduced in size and weight, the response of the movement to the load can be made more sensitive, and the measurement accuracy can be improved. If a force is applied from the free end 4b of the lever 4, the force can be increased and transmitted to the movable portion 32 (the movable portion 14 of the roberval mechanism 2), so that the lever 4 is braked with a small force at the free end 4b. become able to.

The electronic balance 1 can withstand use as a dynamic balance in which a heavy object such as a conveyor is provided on a load receiving member. This rigidity is obtained because the roberval mechanism 2 has a relatively wide width W1. Due to the improvement of the rigidity, the electronic balance 1 can withstand an impact or the like when the object to be weighed is placed on the conveyor.

As described above, if there is an unexpected fallen object on the movable section 14 side of the roberval mechanism 2 during the mass measurement of the object to be weighed, the movable section 14 is lowered and the spring section 20 of the roberval mechanism 2 and Spring parts 34 and 36 which are movable parts of lever 4
There is a possibility that a shock may be applied to such an extent that it is damaged. However, in the electronic balance 1 configured as described above, the movable part 1 is moved by the stopper 23 at the lower surface position of the movable part 14.
Since the range of movement of 4 is restricted, the movable section 14 does not move more than necessary, and no impact load is applied to the spring section 20 and the spring sections 34 and 36.

The distance t between the stopper 23 and the upper surface of the base plate 10 can be changed by rotating the screw portion 23a. Thereby, the interval t, which is the moving range of the movable section 14, can be adjusted according to the mass of the object to be measured, which is to be measured. This adjustment may be set using a gap gauge or the like, for example, when the upper limit of the object to be weighed to be measured is 3000 g, the interval t ≒ 0.3 mm or the like.

Therefore, in the electronic balance 1 described above, the spring part 20 of the roberval mechanism 2 and the movable parts (spring parts 34, 36) of the lever 4 are controlled by the stopper 23 that regulates the moving range of the movable part 14 of the roberval mechanism 2. ) Can be protected by preventing an impact load that may be applied to the above.

In the above-described embodiment, the movable section 1
The configuration is such that an interval t is formed between the base plate 4 and the base plate 10, but is not limited thereto. Specifically, FIGS. 10 and 11
As shown in FIG. 2, there is a configuration in which a space t is formed between the load receiving member 42 fixed on the movable portion 14 and on which a conveyor or the like is placed and the base plate 10.

The load receiving member 42 has a substantially rectangular movable portion 1.
4 has a downward substantially U-shaped mounting portion 42a so as to contact and cover the upper surface side, the front side surface, and the rear side surface. The mounting portion 42a is screw-fixed to the upper surface, the front surface, and the rear surface of the movable portion 14. Thereby, the load receiving member 4
2 is stably attached to the movable portion 14. The upper surface of the movable portion 14 is formed slightly higher than the fixed portion 12 and the roberval portion 18, and
The inner surface of the movable member 14 in contact with the upper surface of the movable portion 14 is formed so as to protrude slightly below the other inner surfaces. This allows
The load receiving member 42 is fixed only to the movable portion 14 so as to cover the upper side of the roberval portion 18 and the fixed portion 12 in a non-contact manner. Then, the fixing portion 1 on the upper surface side of the load receiving member 42
Above the movable portion 14 and the movable portion 14, two support portions 42b to which a not-shown conveyor (or a mounting plate) on which an object to be weighed is mounted are provided. As a result, the conveyor (or mounting plate) is stably fixed to the load receiving member 42 side, and the mass of the object to be weighed placed on a wide range of the conveyor (or mounting plate) is transferred via the load receiving member 42. It can be transmitted to the movable part 14 as appropriate.

The mounting portion 42 covers and covers the load receiving member 42 by contacting the front side and the back side of the movable portion 14.
The screw portion 23 of the stopper 23
a is screwed. As a result, a gap t is formed between the load receiving member 42 and the base plate 10 by the stopper 23. That is, even if the stopper 23 is provided on the member (the load receiving member 42 in the present embodiment) attached to the movable portion 14 to form the interval t, the movement range of the movable portion 14 is regulated, and the roberval mechanism 2 and the lever 4 can be protected.

In all the embodiments described above, the stopper 2 is located at the lower surface position of the movable portion 14 of the roberval mechanism 2 (or the lower surface position of the mounting portion 42a of the load receiving member 42).
3, but not limited to this, not shown,
A stopper 23 may be provided on the upper surface of the base plate 10. That is, the screw portion 23a is screwed on the upper surface of the base plate 10, and the leg portion 23b is disposed on the upper end thereof, whereby the movable portion 14
An interval t is formed between the base plate 10 (or the load receiving member 42).

Further, in all the above-described embodiments, the stopper 23 is attached to each part by the screw portion 23a to form the interval t and the interval t is adjustable. An integral projection may be provided on the member 42) or the base plate 10 and configured as the stopper 23.

[0042]

According to the electronic balance of the present invention, a stopper is provided between the movable portion or the load receiving member fixed to the movable portion and the base plate which movably supports the movable portion, and the phase of the movable portion is adjusted. Regulated range. As a result, even if there is an unexpected fallen object on the movable part side of the roberval mechanism, the stopper regulates the moving range of the movable part and does not move the movable part more than necessary, so that the spring part of the roberval mechanism and the movable of the lever can be moved. These can be protected by preventing an impact load applied to the portion (spring portion).

Further, since the stopper is configured such that the movable range of the movable portion can be adjusted, the movable range of the movable portion is adjusted according to the mass of the object to be measured to be symmetric, and the object to be weighed is adjusted. The above protection can be performed according to the above.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an electronic balance of the present invention.

FIG. 2 is a front view showing a roberval mechanism.

FIG. 3 is a plan view of a roberval mechanism.

FIG. 4 is a right side view of the roberval mechanism.

FIG. 5 is a left side view of the roberval mechanism.

FIG. 6 is a front view showing a lever.

FIG. 7 is a plan view of a lever.

FIG. 8 is a side view of the lever.

FIG. 9 is a cutaway front view showing a state in which a lever is incorporated in the roberval mechanism.

FIG. 10 is a perspective view showing a load receiving member.

FIG. 11 is a left side view in which the load receiving member is attached to the roberval mechanism.

FIG. 12 is a front sectional view showing a conventional electronic balance.

FIG. 13 is a perspective view of the conventional electronic balance.

[Explanation of symbols]

1. Electronic balance, 2. Robarbal mechanism, 4. Lever, 4b
... Free end, 6 ... Balance driving means (electromagnetic coil), 12 ... Fixed part, 14 ... Movable part, 18 ... Robarbal part, 20 ... Spring part, 23 ... Stopper, 42 ... Load receiving member.

Claims (3)

[Claims] 1. A pair of roberval portions (18) having a predetermined length are provided between a fixed portion (12) and a movable portion (14) via a thin spring portion (20), and are weighed. A roberval mechanism (2) for moving the movable part receiving a load in a horizontal state, a base plate (10) for fixing the fixed part of the roberval mechanism and movably supporting the movable part, A stopper (23) provided between the movable part of the roberval mechanism and the base plate to regulate a moving range of the movable part; and a free end (4
b) a lever (4) displaced by a predetermined amount from the equilibrium state; and equilibrium drive means (6) for controlling the movement of the lever to be in the equilibrium state in order to calculate and output the mass of the object to be measured. An electronic balance, characterized in that: 2. A pair of roberval portions (18) having a predetermined length are provided between a fixed portion (12) and a movable portion (14) via a thin spring portion (20). A roberval mechanism (2) for moving the movable part receiving a load in a horizontal state, a base plate (10) for fixing the fixed part of the roberval mechanism and movably supporting the movable part, A stopper (23) provided between the load receiving member (42) attached to the movable part of the roberval mechanism and the base plate to regulate a moving range of the movable part, and interlocked with the movement of the movable part The free end (4
b) a lever (4) displaced by a predetermined amount from the equilibrium state; and equilibrium drive means (6) for controlling the movement of the lever to be in the equilibrium state in order to calculate and output the mass of the object to be measured. An electronic balance, characterized in that: 3. The method according to claim 1, wherein the stopper is configured to adjust a moving range of the movable portion of the roberval mechanism. electronic balance.