JPH10282149A - Cross-coil indicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the magnetism collecting factor of a magnet supported by the pointer shaft of a cross-coil indicator. SOLUTION: A magnet made of a hard magnetic material is coaxially supported by the middle section of a pointer shaft 30 in the hollow section of a bobbin 10 and a discoid magnetism collecting member 80 made of a soft magnetic material is buried in the magnet 70 coaxially with the pointer shaft 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross-coil indicating instrument.

[0002]

2. Description of the Related Art A conventional cross-coil type indicating instrument of this type is disclosed in Japanese Utility Model Laid-Open No. 4-116778. The cross-coil indicator has a hollow bobbin, and a pointer shaft is coaxially and rotatably supported in the bobbin. Also, the magnet
The magnet is coaxially supported at an intermediate portion of the pointer shaft in the bobbin, and magnetic poles having different polarities are formed at both ends in the radial direction of the magnet. The two crossing coils are wound around the outer wall of the bobbin so as to cross each other so as to generate a magnetic flux passing through the hollow portion of the bobbin at right angles to the pointer axis.

[0003]

In the meantime, in the cross coil type indicating instrument having the above-mentioned structure, the magnet is formed of a hard magnetic material. For this reason, since the magnetism collection rate of this magnet is extremely low, the two crossing coils substantially function only as air core coils. Therefore, it can be said that the utilization efficiency of the magnetic flux generated by the two crossing coils is low.

Therefore, even if current is applied to both crossing coils, the density of the magnetic flux generated by these two crossing coils in the magnet is small. For this reason, since the rotating torque given to the magnet by the two crossing coils by the generated magnetic flux is small, it is difficult for the pointer shaft to rotate smoothly. As a result, this causes a decrease in pointing accuracy.

In view of the above, an object of the present invention is to increase the magnetic flux collection of a magnet supported on a pointer shaft in a cross-coil type indicator in order to cope with the above.

[0006]

In order to solve the above-mentioned problems, according to the first to fourth aspects of the present invention, a magnetism collecting member having a high magnetic permeability is provided in the magnet. Thereby, the magnetic fluxes generated by the two crossing coils are collected on the magnetic flux collecting member. For this reason, the amount of magnetic flux generated by the two crossing coils passing through the magnet is significantly increased as compared with the case where no magnetic flux collecting member is provided.

Therefore, the rotational driving force generated by the magnet based on the magnetic flux generated by the two crossing coils is significantly increased, and the pointer shaft can be driven smoothly. As a result, the indicating accuracy of the cross-coil indicating instrument can be remarkably improved. Here, according to the second aspect of the present invention, the magnetic flux collecting member is provided in the magnet at substantially the center of its axial width.

Thus, most of the magnetic flux generated by the two crossing coils is collected through the magnetic poles in the magnet. Therefore, the function and effect of the invention described in claim 1 can be further improved. According to the third aspect of the present invention, the magnet is formed in a cylindrical shape from a hard magnetic material,
The magnetic flux collecting member is formed of a soft magnetic material in a disk shape so as to have an outer diameter smaller than the outer diameter of the magnet.

Thus, the functions and effects of the first and second aspects of the present invention can be further improved. According to the invention described in claim 4, the magnetic flux collecting member is provided coaxially with the pointer shaft in the magnet. As a result, it is possible to maintain a good balance between weight and magnetism around the pointer axis of the magnet. As a result, the function and effect of the invention described in claim 3 can be further improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the present invention is applied to a cross coil type indicating instrument for a vehicle. This cross-coil type indicator is disposed in an instrument panel of a vehicle with a pointer shaft inclined as shown in FIG.

The cross-coil type indicator has a hollow bobbin 10 as a housing.
Is composed of an upper bobbin member 10a and a lower bobbin member 10b molded of resin. Bobbin 10
As shown in FIGS. 1 and 2, the bobbin 10 is held by a lower bobbin 10 b in a casing 20 having a U-shaped cross section, and the bobbin 10 is fixed to a circuit board (not shown) together with the casing 20. ing.

In the bobbin 10, a pointer shaft 30 is supported coaxially and rotatably.
It extends through the scale plate 40 and supports the pointer 50 at the tip. As shown in FIG. 1 and FIG. 2, the both crossing coils 60 are wound around the outer wall of the bobbin 10 in a cross-shaped manner. Is substantially perpendicular to the pointer shaft 30.

A cylindrical magnet 70 is coaxially supported in the hollow portion of the bobbin 10 at an intermediate portion of the pointer shaft 30. Opposite polarities are provided on both opposing portions of the outer peripheral wall of the magnet 70. Magnetic poles are formed respectively. Note that the magnet 70 is formed of a hard magnetic material. As shown in FIG. 1, a magnetism collecting member 80 is coaxially embedded with the pointer shaft 30 inside the magnet 70, and the magnetism collecting member 80 is formed in a disk shape. (See FIGS. 3A and 3B).

Here, the magnetic flux collecting member 80 is
Is located at substantially the center of the axial width of the magnetic flux collecting member 8.
The outer diameter of 0 is smaller than the outer diameter of the magnet 70. The thickness of the magnetic flux collecting member 80 is smaller than the axial width of the magnet 70. Further, the magnetic flux collecting member 80 is formed of a soft magnetic material. In the present embodiment configured as described above, if current is applied to both cross coils 60, a magnetic flux is generated in both cross coils 60 by electromagnetic induction. These magnetic fluxes enter the hollow portion of the bobbin 10.

Here, as described above, since the magnet 70 is formed of a hard magnetic material, the magnetic permeability of the magnet 70 is substantially equal to the magnetic permeability of a vacuum. On the other hand, since the magnetic flux collecting member 80 is formed of a soft magnetic material, the magnetic permeability of the magnetic flux collecting member 80 is much larger than the magnetic permeability of the magnet 70. Therefore, the magnetic flux collecting member 80 is much easier to collect the magnetic flux than the magnet 70. Moreover, the magnetic flux collecting member 80 is embedded in the magnet 70 as described above.

Therefore, each magnetic flux of the two crossing coils 60 is collected on the magnetic flux collecting member 80. This means that the magnetic flux density of the magnet 70 with respect to each of the magnetic fluxes, and consequently the magnetic flux collection rate, is much higher than the case without the magnetic flux collecting member 80. As a result, most of the magnetic fluxes generated from the two crossing coils 60 pass through the magnet 70 as described above.

As a result, the rotational driving force generated in the magnet 70 based on the respective magnetic fluxes of the two cross coils 60 becomes extremely large as compared with the case where the magnetic flux collecting member 80 is not provided. Thereby, the pointer shaft 30 and the pointer 50 can be smoothly rotated, and the pointing accuracy of the pointer 50 can be remarkably improved. In this case, since the outer diameter of the magnetic flux collecting member 80 is smaller than the outer diameter of the magnet 70, each magnetic flux of the two crossing coils 60 always passes through the magnetic pole from the outer peripheral wall into the magnet 70. Therefore, a rotational driving force based on both magnetic poles of the magnet 70 can be effectively generated.

Since the magnetic flux collecting member 80 is located substantially at the center of the axial width of the magnet 70, each magnetic flux of the two crossing coils 60 is efficiently collected by the magnet 70. Therefore, a rotational driving force based on both magnetic poles of the magnet 70 can be generated more effectively. The magnetic flux collecting member 80
Is positioned coaxially with the magnet 70 about the pointer shaft 30, so that the weight balance and the magnetic balance of the magnet 70 about the pointer shaft 30 can be favorably maintained. Therefore, the rotational driving force of the magnet 70 can be constantly stabilized.

In the above embodiment, the magnetic flux collecting member 80 has a disk shape. However, the magnetic flux collecting member 80A having a shape as shown in FIGS. Alternatively, a rectangular magnetic flux collecting member 80B as shown in FIGS. 5A and 5B may be employed instead of the magnetic flux collecting member 80. With these, the same operation and effect as the above embodiment can be substantially achieved.

In implementing the present invention, the magnetic flux collecting member 8
The material forming 0 is not limited to a soft magnetic material, but may be a magnetic material having a high magnetic permeability, for example, ferrite.
In implementing the present invention, the cross-coil indicating instrument is not limited to a vehicle, and may be a cross-coil indicating instrument for various types of industrial equipment.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a cross-coil type indicating instrument according to the present invention.

FIG. 2 is a perspective view showing a configuration in which a scale plate and a pointer are removed from the pointer meter of FIG. 1;

FIGS. 3A and 3B are a plan view and a cross-sectional view of the magnetic flux collecting member of FIG.

FIGS. 4A and 4B are a plan view and a cross-sectional view showing a modification of the embodiment.

FIGS. 5A and 5B are a plan view and a cross-sectional view showing another modification of the embodiment.

[Explanation of symbols]

Reference numerals 10: bobbin, 30: pointer shaft, 50: pointer, 60: cross coil, 70: magnet, 80, 80A, 80B: magnetic flux collecting member.

Claims (4)

[Claims] 1. A hollow bobbin (10); a pointer shaft (30) coaxially and rotatably supported in the bobbin; and a coaxial portion in the bobbin at an intermediate portion of the pointer shaft. Having two magnetic poles magnetized at opposite radial ends with opposite polarities (7).
0), and a cross coil (60) crossed with each other and wound on the outer wall of the bobbin so as to generate a magnetic flux passing through the inside of the bobbin crossing the pointer axis. A cross-coil indicating instrument comprising: a magnetic flux collecting member (80, 80A, 80B) provided in the magnet and having high magnetic permeability. 2. The cross-coil type indicating instrument according to claim 1, wherein said magnetic flux collecting member is located at substantially the center of the axial width in said magnet. 3. The magnet is formed in a cylindrical shape from a hard magnetic material, and the magnetic flux collecting member is formed in a disk shape from a soft magnetic material so as to have an outer diameter smaller than the outer diameter of the magnet. The cross-coil type indicating instrument according to claim 1 or 2, wherein: 4. The cross-coil indicating instrument according to claim 3, wherein the magnetic flux collecting member is provided coaxially with the pointer shaft in the magnet.