JPS6242380Y2 - - Google Patents

Description

[Detailed description of the invention] In a crossed wire type instrument having two coils that are substantially orthogonal to each other and a rotatable permanent magnet located at the center of the coil, one of the coils is approximately It is possible to specify a wide angle by applying a current that varies approximately in relation to Sin and Cos to one coil and the other, and by utilizing the fact that the combined magnetic field generated by both coils rotates beyond the intersection angle of the coils. It is known from Japanese Patent Application Laid-Open No. 51-122468.

In the case where the two coils have the same number of turns in the crossed wire type instrument, if a current is applied to one coil with the relationship ASinθ and the other ACosθ, the rotation angle a of the permanent magnet is a=Tan ^-1 ASinθ /ACosθ
It is determined that a = θ, but in reality, there is a difference between the value of the rotation angle calculated using the number of turns of the coil x the current current as the magnetomotive force and the angle at which the permanent magnet actually rotates. . For example, thickness 6mm, length 17mm, width 9
Using a wire rod with a wire diameter of 0.1 mm on a mm bobbin, turn it inside as the first coil 1000 times (coil resistance approximately 100Ω).
In a crossed wire type instrument, the second coil is wound 1000 times (coil resistance approximately 110Ω) outside the first coil with a 90 degree change in direction. Approximately to the coil of 2
When applying a current that varies according to the relationship of Sin, a=Tan ^-1 1/1= The disadvantage is that a≒42° instead of 45°, resulting in a difference of about 3°.

Conventionally, crossed wire type meters have been widely used as automobile thermometers and fuel gauges, but the difference from the calculated value of about 3 degrees has not been a problem. However, when applied to wide-angle instruments such as tachometers, linearity of indication is required, which requires greater precision than conventional methods, and the angle difference (3〓) described above must be resolved. The cause of this difference is that the distance from the permanent magnet is different between the first coil and the second coil.The first coil is close to the permanent magnet, and the second coil is far from the permanent magnet. This is because even if the magnetomotive force of the coils is the same, the magnetic force that the second coil acts on the permanent magnet is smaller than the magnetic force that the first coil acts on the permanent magnet, and this ratio depends on the wire diameter of the coil, the number of turns, and the bobbin. Varies depending on shape.

The present invention provides a crossed wire type meter that alleviates the above drawbacks by setting the maximum value of the magnetomotive force of the first coil wound on the inside to be smaller than the maximum value of the magnetomotive force of the second coil wound on the outside. A method for making the maximum value of the magnetomotive force of the first coil smaller than the maximum value of the magnetomotive force of the second coil is to set the maximum value of the amplitude of the voltage applied to the first coil to be smaller than the maximum value of the magnetomotive force of the second coil. Although it is conceivable to make the amplitude of the voltage applied to the voltage smaller than the maximum value, the circuit configuration would be complicated, so the present invention is realized with an extremely simple configuration.

FIG. 1 is a diagram of a crossed wire type meter, showing the arrangement of the first coil 1 and the second coil 2 and the structure of the crossed wire type meter. Figure B is a sectional view taken along line A-A. In the figure, 3 is a rotatable permanent magnet, 4 is a pointer shaft fixed to the permanent magnet, 5 is a pointer, 6 is a shield case, and 7 is a dial plate.

FIG. 2 is a diagram showing the difference between the rotation angle of the permanent magnet calculated from the magnetomotive force of each coil and the actually measured angle, and shows the case of the above series. The horizontal axis shows the rotation angle calculated from the magnetomotive force, and the vertical axis shows the difference between the calculated value and the actual value.

FIG. 3 is a diagram showing the effect of adding a series and external resistor to the first coil (inside).

Figure 4 shows the effect when the wire diameter and number of turns of the first coil (inner) are fixed, the wire diameter of the second coil (outer) is selected to be thicker than the first coil, and the number of turns is varied. The vertical axis represents the difference between the calculated value and the measured value (P-P (peak-to-peak) (Fig. 2A).
meaning).

Figure 5 shows the wire diameters of the first coil and second coil,
Effects when combining various numbers of turns (angular error △)
FIG.

FIG. 6 is a diagram showing a specific circuit for driving the crossed wire type meter of the present invention.

For the reasons mentioned above, in the cross-ring type instrument whose cross section is shown in FIG. 1, an error occurs in which one cycle is 180 degrees as shown in FIG. One way to reduce this error is to make the magnetomotive force of the inner coil smaller than the magnetomotive force of the outer coil.
The same wire is used for the second coil, and since the inner coil resistance is lower than the outer coil resistance, it is applied to both coils with an approximate Sin and Cos relationship with respect to the input signal, assuming the same maximum value. In a driving mode in which a changing driving voltage is applied, the actual rotation angle of the permanent magnet becomes increasingly different from the indicated angle calculated from the driving voltage, and when the wires are the same, the first Even if the number of turns of the coil (inner coil) is reduced compared to the number of turns of the second coil, the resistance value will change at the same time, so the magnetomotive force of the inner coil should be made smaller enough to have a correction effect than the magnetomotive force of the outer coil. I can't find any conditions. Therefore, a method of correction as shown in Figure 3 can be considered by connecting an additional resistor in series with the first coil (inner coil) and making the resistance value of the first coil apparently larger than that of the second coil. . When the aforementioned bobbin was wound with 0.1 mm wire 1000 times each, almost complete correction was achieved by adding approximately 20 Ω. Furthermore, as a method that does not use additional resistance, the wire of the first coil (inner coil) is selected to be thinner than the wire of the second coil (outer coil), and the resistance value of the first coil is set to the second coil.
By increasing the resistance value of the first coil
It becomes possible to make the maximum value of the magnetomotive force of the second coil smaller than the maximum value of the magnetomotive force of the second coil. Figure 4 shows the difference between the calculated value and the actual value when the number of turns is changed by winding 0.08 mm wire 1100 times as the first coil and 0.1 mm wire for the second coil with the above-mentioned bobbin dimensions. (Peak to Peak) (2nd
In this example, the difference can be made almost 0 when the second coil is wound 1200 times. This corresponds to the d curve of the angle error Δ shown in FIG.

The intersecting wire type instrument of the present invention can be realized as a wide-angle tachometer by using the drive circuit shown in FIG. The input rotational signal (frequency) is converted into a voltage signal through the Schmitt circuit, monostable multicircuit, integrator circuit, and adder circuit (Fig. 6 D), and this signal is approximately converted to a Cos type output generation means 9. is applied to the first coil as a signal. (FIG. 6-G) Further, the second signal passes through the auxiliary amplifier circuit 10, and is applied to the second coil as a signal via approximately sine-type output generating means 11. (Fig. 6 H) Furthermore, the intermediate voltage of the signals G and H is determined by the Zener diode 13, and the permanent magnet 3 is set to 0 by the combination of the signals G and H.
Rotates between ~270°. In Fig. 6, 12 indicates the external resistor of the present invention, and when no external resistor is used, the 12
A similar effect can be obtained by selecting the coil wire of the second coil to be thinner than the wire of the second coil.

As mentioned above, the present invention is based on the rotation angle of the permanent magnet calculated from the drive voltage of the coil that is generated because the distance from the rotatable permanent magnet is different between the inner coil and the outer coil, and the actual rotation. The difference in angle is achieved by an extremely simple configuration such as adding resistance to the inner coil or selecting the wire of the inner coil to be thinner than the wire of the outer coil, and the rotation angle of the permanent magnet is calculated from the drive voltage and measured. Since the difference in rotation angle can be almost eliminated, not only can the rotation angle of the permanent magnet with respect to the input signal be determined by calculation, but also a wide-angle cross-wire type instrument with good indicating characteristics can be realized.

[Brief explanation of the drawing]

Figure 1A is a plan view of the cross wire type instrument, Figure 1B
is a cross-sectional view taken along line A-A in Figure 1A, Figure 2 is a diagram showing the difference between the rotation angle of the permanent magnet calculated from the magnetomotive force of each coil and the actually measured angle, and Figure 3 is a diagram showing the difference between the rotation angle of the permanent magnet calculated from the magnetomotive force of each coil and the actually measured angle. Figure 4 shows the effect of adding an external resistor to the coil. Figure 4 is a diagram showing the effect of choosing the second coil's wire diameter to be thicker than the first coil and changing the number of turns. Figure 5. is a diagram showing the effect (angular error Δ) of various combinations of wire diameter and number of turns of the first coil and second coil, and Figure 6 is a diagram showing a specific example for driving the crossed wire type instrument of the present invention. It is a diagram showing a circuit. 1...First coil, 2...Second coil, 3
... Permanent magnet, 9 ... Cos type voltage output generating means,
11...Sin type voltage output generation means, 12...Additional resistance.

Claims (1)

[Scope of utility model registration request] orthogonal first and second coils, a rotatable permanent magnet located at the center of the coil, means for generating a Cos-type voltage output approximately in response to an input signal, and an amplitude of the Cos-type voltage. The output of the output generating means is applied to the coil, and an indicating member fixed to the permanent magnet is used to generate an approximately sin-type voltage output having the same amplitude as the coil. It is a cross wire type instrument having an angle indication, in which a first coil is arranged inside and a second coil is arranged outside, and the magnetomotive force of the first coil is set to the maximum value of the magnetomotive force of the second coil. As a means of determining the maximum value of magnetic force to a small value, the wire of the first coil is
A crossed wire type meter characterized in that the wire material is selected to be thinner than that of the first coil, or an additional resistance is connected in series to the first coil.