JPH1183422A - Rotation angle sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To intercept the influence of magnetism from the outside and to miniaturize a sensor, by forming a yoke, which maintains a magnet and forms a magnetic path, in such a shape that the side encloses the surroundings of a magnetic sensor, and by installing the magnetic sensor in the middle position separated by a prescribed distance from both the upper end and the lower end of the inside of the yoke. SOLUTION: The surroundings of a magnetic sensor 70 are covered and shielded with a yoke 40 installed on a cylinder, therefore, lines of magnetic force, which are about to enter parallel to the surface of the magnetic sensor 70 from the outside, cannot enter the inside of the yoke 40. The magnetic sensor 70 is installed in the middle position separated by a prescribed distance from both the upper end and the lower end of the inside of the yoke 40, therefore, lines of magnetic force, which are about to enter from the obliqued lower position against the magnetic sensor 70, are shielded by the side of the yoke 40. When a rotary driving shaft 30 is rotated, the yoke 40 and permanent magnets 60 and 65 are simultaneously rotated around the magnetic sensor 70, so the direction of lines of magnetic force entering parallel to the surface of the magnetic sensor 70, in the surface, is changed, and also the output resistance is changed, and thereby, the angle of rotation of the rotary driving shaft 30 can be detected corresponding to the changed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle sensor used for detecting rotation angles of various devices.

[0002]

2. Description of the Related Art Conventionally, for example, a rotation angle sensor is attached to a rotation shaft of an opening / closing valve, and the opening / closing angle of the valve is obtained by detecting the rotation angle of the rotation shaft.

FIG. 4 is a schematic perspective view showing a main part of a conventional rotation angle sensor of this type. As shown in the figure, in this rotation angle sensor, magnets 220 and 230 are arranged on both sides of a magnetic sensor 210 fixed to a mounting means (not shown), and both magnets 220 and 230 are fixed to a U-shaped yoke 240.
The center of the yoke 240 is fixed to the rotation shaft 250, and the periphery thereof is covered with a case 260.

Here, the magnetic sensor 210 is a magnetic sensor having a function of changing the resistance value when the direction of the magnetic force line applied in the plane direction changes in the plane.

The north and south poles of both magnets 220 and 230 are
The magnetic field lines are arranged so as to be incident parallel to the surface of the magnetic sensor 210.

When the rotating shaft 250 is rotated, the magnets 220 and 230 are moved together with the yoke 240 by the magnetic sensor 210.
, The direction of the line of magnetic force incident on the magnetic sensor 210 changes, the resistance value of the magnetic sensor 210 changes, and the rotation angle of the rotating shaft 250 can be detected.

[0007]

When adjusting or repairing a device equipped with an opening / closing valve or the like to which the above-mentioned rotation angle sensor is attached, an operator sometimes brings the driver closer to the rotation angle sensor. Some have a magnet at the tip, and when this kind of driver approaches the rotation angle sensor, the magnetism may change the resistance value of the magnetic sensor 210.

In particular, the magnetic sensor 21 is moved from the line of magnetic force directed in the direction of arrow a shown in FIG.
The lines of magnetic force penetrating in parallel to the zero plane greatly contribute to the change in the resistance value of the magnetic sensor 210 even if its magnetic flux density is small.

When the resistance value changes, the opening / closing angle of the opening / closing valve or the like that is being measured is erroneously detected, which may lead to a failure of the entire device. A similar problem also occurs when, for example, a component that generates magnetism is mounted near the rotation angle sensor other than the driver.

In order to solve the above disadvantage, the thickness of the case 260 of the rotation angle sensor may be increased so that the magnetic shield is completely formed. It becomes large, and miniaturization is hindered.

The present invention has been made in view of the above points, and an object of the present invention is to provide a rotation angle sensor which can shield the influence of external magnetism and can be downsized.

[0012]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a magnetic sensor, a magnet for applying a magnetic field directed in a direction parallel to a surface of the magnetic sensor, and a magnet holding the magnet. A yoke for forming a path and driving means for rotating either the magnet or the magnetic sensor are provided, and the yoke is formed so that at least a side surface of the yoke surrounds the magnetic sensor. Further, the magnetic sensor is disposed at an intermediate position separated by a predetermined distance from the upper end and the lower end inside the yoke.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an exploded perspective view of a rotation angle sensor according to one embodiment of the present invention. FIG. 2 is an exploded perspective view of a portion where the rotary drive shaft 30, the yoke 40, and the like are integrated. FIG. 3 is a side sectional view of the assembled rotation angle sensor.

As shown in FIG. 1, this rotation angle sensor
The rotation drive shaft 30 to which the yoke 40 was fixed was housed from the lower side of the case 10 in which the bearing cylinder 20 was housed and fixed, and the upper end thereof protruded from the through hole 11 on the upper surface of the case 10, and the magnetic sensor 70 was further attached. An opening 13 on the lower surface of the case 10 is closed by a lid 80. As shown in FIG. 2, the yoke 40 contains a magnet holding member 50 and two permanent magnets 60 and 65. Hereinafter, each component will be described.

As shown in FIGS. 1 and 3, the case 10 is formed by forming a ferromagnetic material such as iron into a cylindrical shape.
The upper surface thereof is provided with a through hole 11 that rotatably passes through the rotary drive shaft 30, and the lower surface thereof is an open opening 13.

On the inner peripheral surface of the case 10, there is formed a step portion 15 having a different inner diameter between a portion accommodating the bearing cylinder 20 and a portion accommodating the yoke 40, and a lid 80 is attached. A step 17 is also formed in the portion.

The bearing cylinder 20 is formed by forming a non-magnetic material such as copper into a cylindrical shape, and has a central hole 21 for rotatably supporting a rotary drive shaft 30 in an oilless manner.
Is provided.

As shown in FIG. 2, the rotary drive shaft 30 is formed by processing a stainless steel material into a cylindrical shape, and has a minus groove 31 on its upper end surface and a ring groove 33 on its outer peripheral side surface. A small projection 35 having a small diameter is provided on the lower end surface thereof.

The yoke 40 is formed of a ferromagnetic material such as iron in a shape in which a cup having a U-shaped cross section is turned down, and a through hole 41 penetrating the small projection 35 is provided on an upper end surface thereof. The lower surface is an open opening 43.

The magnet holding member 50 is formed by molding a synthetic resin into a cylindrical shape, and is provided with notches 51, 51 (only the front side is shown in FIG. 2) at opposing positions on the lower side. ing. The height of the magnet holding member 50 is formed to be approximately half the height of the yoke 40.

The two permanent magnets 60 and 65 have a rectangular parallelepiped shape, and are respectively attached to the notches 51 and 51 of the magnet holding member 50 so that the opposing surfaces have different poles.

The magnetic sensor 70 is formed by forming a desired magnetoresistive pattern on the surface of a flat substrate made of glass, silicon or ceramic.
The resistance value of the magnetoresistive pattern changes in accordance with the direction of the lines of magnetic force incident parallel to the pattern surface, that is, the surface of the substrate.

As shown in FIG. 1, the magnetic sensor 70 is fixed on the upper surface of a columnar mold resin support 73. As shown in FIG. 3, the support base 73 has its lower end fixed to a disk-shaped substrate 77.
It is fixed to the upper surface of. The four lead wires 79 penetrating the lid 80 and connected to the substrate 77 are connected to the magnetic sensor 70 via a circuit pattern 77a formed on the substrate 77 and a flat cable 77b.

The lid 80 is formed by forming a ferromagnetic material such as iron into a disk shape.

Next, in order to assemble the rotation angle sensor, as shown in FIG.
Is inserted into the through-hole 41 of the yoke 40 and its tip is swaged to integrate the two.

Next, the notches 51, 51 of the magnet holding member 50
The permanent magnets 60 and 65 are fixed to the yoke 40 by press-fitting the same through the opening 43 of the yoke 40. As shown in FIG. 3B, both permanent magnets 60, 6
5 is located substantially in the center of the yoke 40.

Next, as shown in FIG. 1, the bearing cylinder 20 is inserted into the case 10 and fixed, and then the ring 90 is inserted into the central hole 21 of the bearing cylinder 20 and the through hole 11 of the case 10. The rotatable drive shaft 30 is rotatably inserted. At that time, the yoke 40 is stored in the case 10. Then, a locking ring 95 shown in FIG. 3 is attached to the ring groove 33 of the rotary drive shaft 30 protruding from the upper surface of the case 10. Then, if the lid 80 is attached and fixed so as to cover the opening 13 of the case 10, the rotation angle sensor is completed.

As shown in FIG. 3B, the rotation angle sensor has permanent magnets 60,
65 are arranged. Therefore, the magnetic sensor 70 has a permanent magnet 65
A line of magnetic force in a direction toward zero is applied. Therefore, the output resistance value of the magnetic sensor 70 is determined according to the direction of the line of magnetic force on the surface of the magnetic sensor 70.

In the case of the present invention, as is apparent from this embodiment, the magnetic sensor 70 is covered and shielded by the cylindrical yoke 40, so that the magnetic sensor 70 is externally parallel to the surface of the magnetic sensor 70. The lines of magnetic force to be incident cannot enter the yoke 40. In the case of the magnetic sensor 70, as described above, the line of magnetic force incident parallel to the surface of the magnetic sensor 70 affects the change in the resistance value. Therefore, it is most effective if the magnetic line of force coming from the side surface of the yoke 40 can be shielded. It is.

In the case of this embodiment, the case 10 is also made of a ferromagnetic material, so that the case 10 is also shielded. However, in the case of the present invention, since the yoke 40 itself has a shielding function, the case 10 It is not necessary to increase the thickness of the rotation angle sensor 10 for shielding, and therefore, the size of the entire rotation angle sensor can be reduced.

In the case of this embodiment, the yoke 40
Since the magnetic sensor 70 is disposed at an intermediate position separated by a predetermined distance from the upper end and the lower end of the inside, the magnetic force lines (especially vector components parallel to the surface of the magnetic sensor 70) entering the magnetic sensor 70 obliquely from below. 3) can be effectively shielded on the side surface of the yoke 40, and the structure is less susceptible to external influences. Further, in the case of this embodiment, since the lid 80 is also made of a ferromagnetic material, the lines of magnetic force that are more likely to enter the magnetic sensor 70 from obliquely below (the opening 43) are effectively shielded. The magnetic sensor 70
The lines of magnetic force perpendicularly incident on the surface do not contribute to a change in the output resistance value of the magnetic sensor 70.

In this embodiment, the permanent magnets 60 and 65 are attached to substantially the center of the inner peripheral surface of the yoke 40, and the opening 43 is covered with a ferromagnetic lid 80. , 65 form a closed magnetic path via the upper surface of the yoke 40 and the yoke 4
The lower portion of the motor has three parts, one forming a closed magnetic path through the lid 80 and the other forming a closed magnetic path through the side surface of the yoke 40. it can.

When the rotary drive shaft 30 is rotated, the yoke 40 and the two permanent magnets 60 and 65 rotate around the magnetic sensor 40, whereby the yoke 40 and the two permanent magnets 60 and 65 in the plane of the magnetic force lines incident parallel to the surface of the magnetic sensor 40. Since the output resistance changes as the direction changes, the rotation angle of the rotary drive shaft 30 can be detected according to the value.

In the above embodiment, the permanent magnets 60, 65
The yoke 40 to which the magnetic sensor 70 is attached is rotated. Alternatively, the yoke 40 may be fixed and the magnetic sensor 70 may be rotated.

Needless to say, the shape and material of each component constituting the rotation angle sensor can be variously modified. That is, for example, the yoke 40 may be a polygonal cylindrical shape, a spherical side surface, or a shape with a hemisphere turned down. In short, it is sufficient that at least the side surface of the yoke has a shape surrounding the periphery of the magnetic sensor.

The magnet holding member 50 is not always necessary, and may be omitted by fixing the permanent magnets 60 and 65 to the yoke 40 directly by bonding or the like.

[0037]

As described in detail above, the present invention has the following excellent effects. The yoke is formed so that the side surface surrounds the periphery of the magnetic sensor, so that the influence of external magnetism can be effectively shut off. Can be reliably shielded, and the rotation angle can always be accurately detected.

Since the shield can be reliably performed by the yoke, it is not necessary to increase the thickness of the exterior case for the shield, and the size can be reduced.

Since the magnetic sensor is disposed at an intermediate position separated by a predetermined distance from the upper end and the lower end inside the yoke, it is possible to effectively shield magnetic lines of force which are externally incident on the magnetic sensor from obliquely above or below.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a rotation angle sensor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a part where the rotary drive shaft 30, the yoke 40, and the like are integrated.

FIG. 3 is a side sectional view of a rotation angle sensor.

FIG. 4 is a schematic perspective view of a main part showing a conventional rotation angle sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Case 30 Rotation drive shaft (drive means) 40 Yoke 60, 65 Permanent magnet 70 Magnetic sensor 80 Cover

Continuation of the front page (72) Inventor Shinichi Akano 2-12-19 Shibuya, Shibuya-ku, Tokyo

Claims (2)

[Claims] A magnetic sensor; a magnet for applying a magnetic field directed in a direction parallel to a surface of the magnetic sensor; a yoke for holding the magnet to form a magnetic path; and any one of the magnet and the magnetic sensor. A rotation unit for rotating one of the magnetic sensors, wherein at least a side surface of the yoke is formed so as to surround a periphery of the magnetic sensor. 2. The rotation angle sensor according to claim 1, wherein the magnetic sensor is disposed at an intermediate position separated by a predetermined distance from an upper end and a lower end inside the yoke.