JPS5817431B2 - Movable magnet type instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a movable magnet type instrument that allows easy finger adjustment.

In various meters, it is necessary to adjust the index in order to display measured values correctly.

Conventional index adjustment means for a movable magnet needle include: ■ Demagnetization of the movable magnet to which the pointer is attached; ■ Demagnetization of the excitation magnet that applies one herk of excitation to the movable magnet; and ■ Excitation. Changes have been made to the magnetic coupling coefficient of the magnetic stomach, and (1) the magnetic coupling coefficient of the driving magnetic field.

However, such conventional finger index adjustment means has the following drawbacks.

The disadvantages of adjusting the index by demagnetizing are that it requires equipment for demagnetization, which increases the size of the manufacturing equipment, and that it is extremely difficult to make fine adjustments, so if it is demagnetized too much, it must be reapplied. In addition, the permanent magnet material used is limited to cast magnets that can be relatively easily attached and detached.

On the other hand, the disadvantages of the index adjustment means by changing the magnetic coupling coefficient are (1) the meter itself must be equipped with a mechanism for index adjustment, which increases the size of the instrument, and the adjustment requires skill. Therefore, productivity may be hindered.

The present invention has been made in order to eliminate such conventional drawbacks, and includes a finger index adjusting magnetic body that generates a ferromagnetic torque in the same phase as the excitation torque of the excitation magnet, which can be moved forward and backward. By appropriately changing the position of this long magnetic screw, the finger index can be easily adjusted.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a disc-shaped movable magnet, and two poles, N and S, are magnetized in parallel on both sides facing each other in the radial direction.

The movable magnet 1 is provided integrally with a rotating shaft 2 provided at its center O, and the rotating shaft 2 is rotatably supported by a bobbin 3 that accommodates the movable magnet 1.

A pointer 4 is fixed to the upper end of the rotary shaft 2 protruding from the bobbin 3, so that when the movable magnet 1 rotates, the pointer 4 also rotates.

A pair of excitation magnets 5 and 5' are provided on the bobbin 3 to face the magnetic poles of the movable magnet 1, and the excitation torque of these excitation magnets causes the movable magnet 1 to rest at a stable point. ing.

Furthermore, a pair of drive coils 6 and 6' are wound around the bobbin 3 so as to be located on the X and Y axes, and the drive coils 6 cover the excitation magnets 5 and 5'.

When a current flows through these drive coils 6, 6', a magnetic flux proportional to this current is generated, and this magnetic flux rotates the movable magnet 1 by a predetermined angle, and the pointer 4 indicates the current value or superimposition value of the current flowing at that time. It is supposed to be done.

As is clear from the above description, the bobbin 3 is a bearing part for the movable magnet 1, a winding frame for the drive coil 6°6', and also serves as a base for assembling other parts. It is housed in a shield case 7 so as not to be affected by magnetic fields.

In this embodiment, two excitation magnets are provided, but one or more may be provided as required. Also, although the drive coil is wound on the excitation magnet, it may be wound in the opposite direction. I did 1
An excitation magnet may be provided above the drive coil.

According to the present invention, the movable magnet type instrument as described above is further provided with a finger index adjustment magnetic screw 8 that generates a ferromagnetic torque in the same phase as the excitation torque produced by the excitation magnets 5 and 5'. , 8' are provided so as to be movable forward and backward.

These adjusting screws 8, 8' are connected to a pair of screw holes 9, 9 formed by swaging or the like on opposite sides of the shield case 7 on an extension line connecting the magnetic poles of the movable magnet 1.
' is screwed so that it can move forward and backward in the direction of the magnetic pole of the movable magnet 1.

The index of the pointer 4 can be adjusted by advancing these adjustment screws 8, 8' appropriately into the shield case 7 or withdrawing them to the outside as necessary using a screwdriver or the like. The operation will be explained in detail with reference to FIGS. 3 to 10.

First, the drive coil 6.6' is connected to X and Y as described above.
Since it is wound around the bobbin 3 so that it is located on the axis,
Magnetic flux φ is generated when current flows through these drive coils.

,φ. , have a phase difference of 90° and 180° with respect to the magnetic flux φ generated by applying the excitation torque from the excitation magnets 5 and 5' to the movable magnet 1, respectively, and this is shown in a vector diagram as shown in Fig. 3. It becomes like this.

Therefore, if a current of 1 is now flowing through the drive coil 6, 6', and the magnetic fluxes generated at this time are φ and φ, the +Y-axis vector in Fig. 3 is φ0, the +X-axis vector is φ11, and φ Ct It is expressed as the difference (φ, −φ□,) from the φ□7 vector with a phase difference of 180°, and therefore, as shown in Figure 4, the combined back 1 hel of these is φ and the deflection angle is θ. becomes.

This deflection angle θ is the rotation angle of the movable magnet 1 based on the current flowing through the drive coil 6.6', and therefore the pointer 4
is the deflection angle.

By the way, the deflection angle on the scale plate that the pointer 4 should indicate when a current of 1 flows through the drive coil 6, 6' is θ.

Then, it is necessary to correct the aforementioned θ to θ, but
This correction is effected by adjusting screws 8, 8'.

That is, the magnetization of the movable magnet 1 is dipole row magnetization as described above, and as explained in FIG. and
The waveform is as shown in FIG.

Therefore, the equivalent magnetic circuit of FIG. 1 incorporating such a movable magnet 1 becomes as shown in FIG. It is possible to generate magnetic flux φ1 having the same phase.

Also, as shown in Fig. 10, the magnetic flux φ from one drive coil 6.6' forms a closed loop passing from the center of the coil through screw 8°8' and shield case γ.
, 8' are advanced closer to the center of the drive coil 6°6', the magnetic resistance of the coil magnetic flux φ decreases, and φ apparently increases by +Δφ (on the contrary, when screws 8, 8' are retracted, When moving away from the center of the drive coil 6.6', φ decreases by one Δφ).

The increase in φ and the increase in φ1 due to the advance and retreat of the screws 8 and 8'
The desired deflection angle θ as shown in FIG. 5 can be obtained by increasing (φ+φF,)−φ0. and φ
The composite vector of 1+Δφ is φ8, and the deflection angle is θ.

In addition, when adjusting the index using these screws 8 and 8', +
The contribution rate of Δφ is about 10%, and the contribution rate of φ1 is about 90%, so the fingertip adjustment by the screws 8, 8' is mainly performed by φV.

For reference, the measurement data when the present invention is applied to a general automobile electric meter shows that the 6th
It exhibited the characteristics shown in the figure.

In FIG. 6, a indicates the index characteristic before adjustment, b indicates the appropriate index characteristic, and C indicates the maximum sensitivity characteristic. Curves a and C are created by moving the adjustment screws 8 and 8' back and forth. The finger index can be adjusted within the range surrounded by , and during this adjustment, it is approximately ±10%.

As described above, according to the present invention, there is provided a movable magnet type instrument in which the finger index can be easily adjusted simply by moving the adjusting screw forward and backward, and the adjustment does not require special skill. There is no need to increase the size of the device itself, and since there is no need for magnetization/demagnetization, there is an advantage that the manufacturing equipment does not need to be increased in size.

It should be noted that the present invention is of course not limited to the above-mentioned embodiment, but can be implemented with various modifications without departing from the scope of the invention. Also, similar effects can be obtained even if the present invention is implemented in a crossed coil type movable magnet type instrument.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the movable magnet type instrument according to the present invention, and FIG. A vector diagram for explaining the effect of the finger adjustment according to the present invention, FIG. 6 is a diagram showing an example of the index characteristic of a meter to which the present invention is applied, and FIG. 7 is a diagram showing the N of the movable magnet.
FIG. 8 is a diagram showing the magnetization relationship between the pole and the S pole, FIG. 8 is a diagram showing the waveform thereof, and FIGS. 9 and 10 are magnetic circuit diagrams for explaining the present invention in detail. 1...Movable magnet, 2...Rotating shaft, 3.
...Bobbin, 4...Pointer, 5,5'...
...Excitation magnet, 6, 6'... Drive coil, 7... Shield case, 8, 8'...
・Finger adjustment screw, 9, 9'...Screw hole.

Claims (1)

[Claims] 1 Includes a movable magnet to which a pointer is attached, an excitation magnet fixed at a predetermined position that applies an excitation torque to the movable magnet, and a drive coil that drives the movable magnet by the flow of the current to be measured. In a movable magnet type instrument, the movable magnet, the excitation magnet, and the driving coil are housed in a shield case in which the advancing and retracting directions are directed toward the magnetic pole direction of the movable magnet at opposing positions on an extension line connecting the magnetic poles of the movable magnet. Screw on a pair of magnetic screws for adjusting the finger index,
A movable magnet type instrument characterized in that a ferromagnetic torque having the same phase as the excitation torque by the excitation magnet is generated by advancing and retracting the screw.