JPS61104228A - Force generation mechanism - Google Patents

Abstract

PURPOSE:To measure force accurately, by measuring voltage generated in the hole element arranged in close vicinity to the coil placed in a magnetic field. CONSTITUTION:A dish 6 having an article (not shown in the drawing) to be measured placed thereon is suspended from one end of the rod 2 supported by a fulcrum 4 and a part 14 to be detected is provided to the other end thereof so as to be opposed to an approximate switch 15. A bobbin 9 having a coil 10 therearound is connected to the rod 2 in the side of the part 14 to be detected and constitutes a load measuring actuator along with a permanent magnet 11, a yoke 12 and a hole element 20. At the time of measurement, the article to be measured is placed on the dish 6 and a current is flowed to the coil 10, in such a state that the approximate switch 15 is opposed to the part 14 to be detected, to take balance so as to make the rod 2 horizontal. The voltage of the hole element 20 at this time is measured to calculate the force acting on the coil 10. By this method, force can be measured accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a force generating mechanism used, for example, in a weighing machine, and particularly relates to a force generating mechanism used in a weighing machine. It relates to a force generation mechanism designed to generate force.

[Conventional technology and problems]

Figure 4 schematically shows the conventional force generation mechanism, which includes a main yoke (4υ), a center yoke (4υ), and a permanent magnet (4υ).
It consists of a coil (49) disposed in the air gap (43).The coil (49) is supported movably in the direction of arrow F.The constant magnetic flux from the permanent magnet (43 is indicated by solid line arrow B). As shown by , the coke flows through the center yoke (4), the air gap (2), and the main coke (4υ).

When a current is passed through the coil (49), a force F = B is generated in the direction of arrow F at a portion of the conductor length t (where B is the magnetic flux density), and the force F and the current are Since it is proportional, force F is measured from the value of current 1 using this proportional relationship.

However, strictly speaking, force F and electric current are not proportional. In other words, when a current I is passed through the coil (4!19), a magnetic flux ΔB as shown by the dotted line is generated by the coil itself. Since this magnetic flux ΔB is proportional to the current, ΔB=k I (k is a proportionality constant). Then, when current is passed through the coil (4), the magnetic flux density in the air gap (44) becomes B = B, + kI or B, -kI. Therefore, strictly speaking, the force acting on the coil (49) is (B, ±kI)It.

In other words, F=B, tI±ktl", and the electrician's 2
Since there is a term proportional to the power of the current, it cannot be said that the force F is linearly proportional to the current.

Therefore, for example, in a weighing machine, a problem arises in that accurate weighing cannot be performed using the measurement method using this force generating mechanism.

[Object and structure of the invention]

The present invention was made in view of the above problems, and an object of the present invention is to provide a force generation mechanism that can measure force more precisely than before. According to the present invention, in the above configuration, a Hall element is connected in series to the coil, and the Hall element is disposed close to the coil in the magnetic field, and the Hall element is connected to the coil in series. This is achieved by a force generating mechanism characterized in that the force generated in the coil is measured by the generated voltage.

〔Example〕

Below, regarding the horizontal frame type weighing machine according to the embodiment of the present invention (2
) will be explained with reference to the surface.

In the figure, the horizontal frame weighing machine is shown as a whole (IJ),
The horizontal frame, so-called pole (2), is supported at a fulcrum (4) on one of the columns (3a) of the frame (3), and on its -shoulder side suspends a plate (6) via a fulcrum (5). It's hanging. Further, at the other end side, an actuating rod (8) of a load measuring actuator (7) is pivotally mounted.

The load measuring actuator (7) is connected to the above-mentioned actuating rod (8
) in addition to the bobbin (9), the coil Q1 wound around it,
Permanent magnet a] J, yoke (12a) (12b) (12c
) and void? Inside, a yoke (12b
) consists of a Hall element (1) fixed to a permanent magnet (
The magnetic flux B from lIυ is connected to the coil Q as shown by the solid arrow.
(It flows across the yoke (12a x 12h) (12). When a direct current is passed through the coil QQ in a predetermined direction, a magnetic flux ΔB as shown by the dotted line also flows, but this current and the magnetic flux in the air gap f Force F in the downward direction due to interaction
occurs and pulls the actuating rod (8) downward as shown by the arrow. By controlling the magnitude of the current flowing through the coil aq, this force F is adjusted and balanced with the weight of the object to be measured placed on the placing plate (6). It is configured as follows.

As shown in Fig. 3, the coil CIQ and the Hall element (1) are connected in series to the variable DC power supply [2D, and the Hall element (
The voltage generated in 7) is configured to be measured by a voltage measuring device.

A stopper mounting block a3 is fixed on the other support column (3b) of the frame (3), and a through hole (
13a) is inserted through the tip of the rod (2), and the running detection part (metal) α formed at the tip is at a predetermined distance from the proximity switch αQ when the rod (2) is balanced as shown. They are facing each other.

Screw holes (13hX13c) are formed above and below the through hole (13a) of the stopper mounting block α field, and stopper screws aOαη are screwed into these holes, respectively. By adjusting the screw aυαη, the displacement A of the rod (2) is determined. In other words, the rod (2) is tightened by the upper screw αQ.
The upper limit of rotation is determined, and the lower screw thread (2)
The lower limit of rotation is determined. During displacement A, or the upper and lower limits of rotation are the characteristics of the proximity switch (to), the distance between this switch (to) and the detected part a4 of pole (2), and the fulcrum (4
) (5), the distance between the fulcrum (4) and the operating rod (8), etc.

The embodiment of the present invention is configured as described above, and its operation, effects, etc. will be explained next.

Now, if the object to be measured is placed on the mounting plate (6), the rod (
2) rotates clockwise in the figure around the fulcrum (4). At the same time, a current is applied from the variable DC power supply (2υ) to the coil 4 of the actuator (7), and the actuating rod (8)
A downward force F is applied to (i.e., rotates the shaft 2 (2) counterclockwise around the fulcrum (4).

When the object to be measured is placed on the mounting plate (6)? (2) rotates clockwise, but the tip of the rod (2) collides with the lower end of the stopper screw, preventing further upward rotation. The proximity switch aQ detects that the rod (2) is above the balance position, and the current in the coil (IQ) of the actuator (7) is increased.The force F acting on the actuating rod (8) increases. increases, and the rotational force of the rod (2) in the counterclockwise direction increases.In other words, the rotation force of the rod (2) increases.
increases the rotational force toward the balance position.

When the actuator (2) rotates downward beyond the balance position, the proximity switch (c) detects this and the current flowing through the coil Q (l) of the actuator (7) is reduced. The current flowing through the coil (10) is assumed to be a constant value. Conventionally, the voltage VH applied to the plate (6) is measured from this value. The weight of the object to be measured is determined by measuring it with the instrument (23).

That is, if current is flowing through the coil a1, the magnetic flux density B in the air gap 2 at that time is as described above.
= Ba±kI (however, in this embodiment, Ba-kI is calculated based on the direction of the current). Since the Hall element (E) is connected to the coil in the @ column, the current value flowing through it is also . Therefore, the voltage generated in the Hall element - = I
(3o±kI) (where R is a constant specific to this Hall element CIC).On the other hand, the force acting on the coil force F=
(Bo±kI)It (t is the total length of the coil αG), so the relationship between F and ■ is as follows.

That is, since the force F is linearly proportional to the voltage V)I,
The force F can be easily determined from the voltage ■. Since the Hall element (1) detects the actual magnetic flux density B in the air gap t, the force F, that is, the weight of the object to be measured, can be determined with conventional precision.

The embodiments of the present invention have been described above, and the present invention is, of course, not limited thereto, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, a proximity switch (to) was used to detect the position of the rod (2), but a differential transformer or a photoelectric switch may be used instead.

Furthermore, in the above embodiments, the mounting plate (6) suspended from the fulcrum (5) was used to load the weight of the object to be measured on the rod (2), but the load was transferred via another machine tank. No matter what you do, it's hard.

In addition, in the above embodiment, the load actuator and eta (7)
.

In this case, the yokes (12a), (12h), and (12c) have an O shape that is different from that shown in FIG. stomach.

In addition, in the above embodiment, a permanent magnet C is used to provide a constant magnetic field.
11J was used, but a DC electromagnet may be used instead.

In addition, in the above embodiment, the acte and eta (7) are the weighing machine (
II, but is applicable to other devices as well.

〔Effect of the invention〕

As described above, according to the force generation mechanism of the present invention, it is possible to accurately detect the magnitude of the force acting on the coil from the voltage value generated in the Hall element.

[Brief explanation of drawings]

Claims (1)

[Claims] In a force generation mechanism that generates force by passing a current through a coil placed in a constant magnetic field, a Hall element is connected in series to the coil, and the Hall element is placed in the magnetic field. A force generating mechanism, characterized in that the force generating mechanism is arranged close to the coil and measures the force generated in the coil by the voltage generated in the Hall element.