JPH09236403A - Magnetic rotation angle sensor - Google Patents

Abstract

(57) [Abstract] [Problem] To obtain uniform sensitivity regardless of the measurement position. SOLUTION: In this magnetic type rotation angle sensor 100,
A parallel magnetic field in the X direction is uniformly generated in the internal space of the magnetic circuit 15. Then, the linear Hall IC is rotated relative to the magnetic circuit 15 in the internal space of the magnetic circuit 15 (point b, point c, point b ′). In this way, when the linear Hall IC is rotated in a uniform parallel magnetic field, the magnetic flux density detected by the linear Hall IC changes in proportion to the change in the rotation angle and the distance from the magnetic member 19. Therefore, the sensitivity of the magnetic rotation angle sensor 100 is made uniform regardless of the measurement position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic rotation angle sensor, and more particularly to a magnetic rotation angle sensor for measuring a relative angle between a magnetic circuit and a magnetic sensor in a non-contact manner.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing an example of a conventional magnetic rotation angle sensor. In the magnetic rotation angle sensor 500, the magnetic circuit 1 is composed of two annular magnetic members 2 and 3 and two wedge-shaped magnets 4 and 5.

A rotating shaft 6 penetrates through the center of the magnetic circuit 1. An arm 7 extends from the rotary shaft 6 in the radial direction, and a hall element 8 is attached to the tip of the arm 7. The Hall element 8 is arranged so as to detect the magnetic flux density in the longitudinal direction of the arm 7. The magnets 4 and 5 are
The magnets are arranged so as to face each other about the rotation axis 6 and to pass a magnetic flux from the N pole of one magnet 4 (5) to the S pole of the other magnet 5 (4).

The magnetic flux leaking from the magnetic members 2 and 3 in the radial direction of the magnetic circuit 1 becomes weaker with distance from the magnets 4 and 5, and becomes substantially zero at a position of 0 degree in the drawing.

When the Hall element 8 rotates, the distance between the magnets 4 and 5 and the Hall element 8 changes, so that the magnitude of the magnetic flux density detected by the Hall element 8 changes. From the change in the magnetic flux density, the relative rotation angle between the Hall element 8 and the magnetic circuit 1 can be obtained.

FIG. 11 is a graph showing the magnetic flux density detection characteristics of the magnetic rotation angle sensor 500. in this way,
It can be seen that the magnetic flux density increases as the Hall element 8 approaches the magnet 4 (magnet 5).

[0007]

However, in the above conventional magnetic rotation angle sensor 500, as shown in FIG. 11, as the Hall element 8 approaches the magnet 4 (5),
The magnetic flux density detected by the Hall element 8 rapidly increases. Therefore, there is a problem in that the sensitivity of the magnetic rotation angle sensor 500 remarkably differs depending on the measurement position.

Therefore, the present invention has been made in view of the above, and an object thereof is to obtain a magnetic rotation angle sensor which can obtain uniform sensitivity regardless of the measurement position.

[0009]

In order to achieve the above object, in the magnetic rotation angle sensor according to claim 1, a parallel magnetic field in a specific direction is uniformly generated in the internal space of the magnetic circuit, and the magnetic circuit The magnetic sensor is rotated in the internal space of to measure the relative angle between the magnetic sensor and the magnetic circuit in a non-contact manner.

In order to achieve the above-mentioned object, the magnetic rotation angle sensor according to the second aspect has a columnar shape.
Each magnet and two pole-shaped magnetic members, the S poles of the two magnets are connected to each other by the one magnetic member, and the N poles of the magnets are connected to each other. A magnetic circuit having a structure connected by a magnetic member and a rotation axis perpendicular to a parallel magnetic field plane in a specific direction formed by the magnetic circuit are provided at the center of the magnetic circuit, and a predetermined distance is provided from the rotation axis. The magnetic sensor is disposed, the magnetic sensor is rotated about the rotation axis, and the relative angle between the magnetic circuit and the magnetic sensor is measured in a non-contact manner.

In order to achieve the above object, in the magnetic rotation angle sensor according to claim 3, the magnetic circuit of the magnetic rotation angle sensor (claim 2) has a substantially square internal space. Is.

In order to achieve the above object, in the magnetic rotation angle sensor according to claim 4, a magnetic member is provided around the rotation axis of the magnetic rotation angle sensor (claim 2 or 3). The magnetic sensor is provided on the magnetic member.

Further, in order to achieve the above object, in a magnetic type rotation angle sensor according to a fifth aspect, a rotation axis of the magnetic type rotation angle sensor (any one of the second to fourth aspects) is centered. Two magnetic sensors are arranged to face each other.

[0014]

According to the magnetic type rotation angle sensor of the first aspect of the present invention, the magnetic sensor is rotated in a uniform parallel magnetic field. Therefore, for changes in the rotation angle,
The change in the magnetic flux density detected by the magnetic sensor becomes uniform, and the sensitivity of the magnetic rotation angle sensor becomes uniform regardless of the measurement position.

Further, according to the magnetic type rotation angle sensor of the second aspect of the present invention, the two magnetic poles of the two magnets are connected by the magnetic member to form a magnetic circuit. A parallel magnetic field in a specific direction can be generated substantially uniformly in the internal space of the. Then, by rotating the magnetic sensor about the rotation axis in this internal space, uniform sensitivity can be obtained in the entire measurement range of the magnetic rotation angle sensor.

Further, according to the magnetic rotation angle sensor of the third aspect of the present invention, since the internal space of the magnetic circuit of the magnetic rotation angle sensor (claim 2) is formed into a substantially square shape, the internal space is concerned. In, the parallel magnetic field in a specific direction can be obtained more uniformly.

According to the magnetic type rotation angle sensor of the fourth aspect of the present invention, since the magnetic flux passes through the magnetic member provided around the rotation axis, a large magnetic flux density can be obtained. Further, since the magnetic flux hardly leaks into the magnetic member, it is unlikely to be affected by the material of the rotating shaft that penetrates it. Further, since the magnetic sensor is provided on the magnetic member, the distance between the magnetic sensor and the magnetic circuit is constant, and the fluctuation of the sensitivity can be prevented.

According to the magnetic rotation angle sensor of the fifth aspect of the present invention, even if the magnetic sensor is a double system,
Since the sensitivity of the magnetic rotation angle sensor is made uniform as described above, the output signal can be monitored with high accuracy. Further, the double type magnetic rotation angle sensor can be easily constructed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

(Embodiment 1) FIG. 1 is a front view showing a magnetic rotation angle sensor according to Embodiment 1 of the present invention. FIG. 2 is a side view of the magnetic rotation sensor shown in FIG.

In this magnetic type rotation sensor 100, 1
Reference numerals 7 and 18 are magnets. The N poles of the magnets 17 and 18 are connected by a magnetic member 19 and the S poles are connected by a magnetic member 20 to form a magnetic circuit 15.
As the magnets 17 and 18, samarium-cobalt magnets which are excellent in temperature characteristics and strong are used. Magnets 17, 18
Has a size of 17.5 mm × 1.5 mm × 4.0 mm.

The magnetic members 19 and 20 are made of a high magnetic permeability material such as iron, and a magnetic stainless material is used in consideration of corrosion resistance. The dimensions of the magnetic members 19 and 20 are 20.5 mm × 1.0 mm × 4.0 mm. 1
Reference numeral 6 denotes a holder made of a non-magnetic material, which is a magnetic circuit 15
Hold. The holding body 16 has a bearing hole 16a into which the shaft whose rotational angle is to be measured is inserted and fixed. This holder 1
6 is rotatable with the magnetic circuit 15 in the direction of the arrow in the figure. Reference numeral 21 is a linear Hall IC for detecting the magnetic flux density of the magnetic circuit 15 in the radial direction of rotation. The linear Hall IC 21 is arranged at a predetermined position from the center of the magnetic circuit 15 and faces the magnetic circuit 15.

The linear Hall IC 21 is a type of semiconductor magnetic sensor that outputs a voltage proportional to the magnitude of the magnetic flux density, and is a package of a Hall element, an amplifier circuit and the like. The thickness of this linear Hall IC 21 is 1 mm. Further, when the linear Hall IC 21 comes closest to the magnetic circuit 15, the gap between them is 1.
It is set to 5 mm. In addition, the Linear Hall IC21
Are electrically connected to the circuit board 22.

When the magnetic circuit 15 rotates, the positional relationship between the linear Hall IC 21 and the magnetic circuit 15 changes, and the magnetic flux density detected by the linear Hall IC 21 changes. As a result, the output voltage of the linear Hall IC 21 changes, and the relative angle between the linear Hall IC 21 and the magnetic circuit 15 can be measured.

FIG. 3 is an explanatory view showing the principle of detecting the rotation angle. First, the magnetic flux leaked from the N pole of the magnet 17 tries to pass through the magnetic member 19. However, the magnetic member 19
Since the N pole of the magnet 18 is connected to the
The magnetic flux leaking from the N pole of No. 8 also tries to pass through the magnetic member 19. Therefore, the magnetic flux leaking from the magnet 17 and the magnet 18
The magnetic flux leaked from the magnetic member 19 repels in the magnetic member 19, and the magnetic flux leaks in a direction substantially perpendicular to the magnetic member 19 (X direction in FIG. 3). Therefore, in the internal space of the magnetic circuit 15, a substantially parallel magnetic field is generated from left to right in the figure.

FIG. 4 is a graph showing measured experimental values of the parallel magnetic field. The parallel magnetic field measurement experiment was performed using a Hall element. The graph in FIG. 4 shows the magnetic flux density Bx in the X direction in FIG. 3 detected by the Hall element when the Hall element is moved from point a to point b in FIG. The graph in FIG. 4 shows the magnetic flux density By in the Y direction in FIG. 3 detected by the Hall element when the Hall element is moved from point a to point b ′ in FIG.

As a result of the measurement, magnetic flux was detected in the X direction in FIG. 3, but almost no magnetic flux was detected in the Y direction in FIG. Therefore, in the internal space of the magnetic circuit 15, X in FIG.
It was found that a parallel magnetic field in the direction was generated. The magnitude of the magnetic flux density Bx was 10 times or more the magnitude of the magnetic flux density By.

Returning to FIG. 3, the linear Hall IC 21 (see FIG.
When (not shown) is at the position of point b (θ = −90 degrees), the linear Hall IC 21 and the magnetic member 19 are closest to each other. Further, the magnetic flux detection direction of the linear Hall IC 21 coincides with the same direction as the parallel magnetic field (X direction in FIG. 3).
Therefore, the magnetic flux density detected by the linear Hall IC 21 becomes maximum.

Next, when the linear Hall IC 21 is relatively rotated and reaches the position of the point c (θ = −45 degrees), the distance between the linear Hall IC 21 and the magnetic member 19 is increased, and the magnetic flux of the linear Hall IC 21 is detected. The direction and the X direction in FIG. 3 are 4
Make an angle of 5 degrees. That is, the magnetic flux density detected by the linear Hall IC 21 becomes smaller because the linear Hall IC 21 is separated from the magnetic member 19 and the magnetic flux detection direction of the linear Hall IC 21 is deviated from the magnetic field direction. As a result, the magnetic flux density detected by the linear Hall IC 21 at the position of the point c becomes about 1/2 of the point b (confirmed later by experimental data).

Subsequently, when the linear Hall IC 21 is relatively rotated and reaches the position of the point b '(θ = 0 degree), the magnetic flux detection direction of the linear Hall IC 21 and the X direction in FIG. 6 form an angle of 90 degrees. Therefore, the magnetic flux density detected by the linear Hall IC 21 becomes substantially zero.

FIG. 5 is a graph showing changes in the magnitude of magnetic flux density with respect to the rotation angle θ. When the inventors measured the change in the magnitude of the magnetic flux density of the magnetic rotation angle sensor 100, a linear output characteristic with respect to the rotation angle θ was obtained as shown in the figure. That is, if the magnitude of the magnetic flux density is replaced with the magnitude of the output voltage of the magnetic rotation angle sensor 100, it means that a linear output characteristic is obtained over the entire circumference of 360 degrees.

FIG. 6 is an explanatory view showing a case where the magnetic rotation angle sensor 100 is applied to an electronically controlled throttle valve of an engine. Air is guided to an engine (not shown) through an intake pipe 9. The intake pipe 9 is provided with a throttle valve 10, and the opening amount of the throttle valve 10 limits the amount of air taken into the engine. The throttle valve 10 is fixed to a throttle shaft 11 by screwing or the like, and a first gear 12 is attached to one end of the throttle shaft 11. A second gear 13 is meshed with the first gear 12, and the second gear 13 is directly connected to the motor 14.

The magnetic rotation angle sensor 100 is arranged between the first gear 12 and the throttle valve 10, and the throttle shaft 11 is fixed through the bearing hole 16a of the holder 16. Controller unit (not shown)
When the motor 14 is rotated by a command from the rotation, the rotation is decelerated by the gears 12 and 13 to move the throttle valve 10 by a predetermined angle and control the amount of air taken into the engine.

At this time, the actual opening of the throttle valve 16 is detected by the magnetic rotation angle sensor 100. That is,
When the throttle shaft 11 rotates, the magnetic circuit 15 rotates in conjunction with it. By this rotation, the linear hall IC2
The magnetic flux density detected by 1 changes. Then, the rotation angle of the throttle valve 10 is measured from the change in the magnetic flux density. Subsequently, the controller unit monitors whether or not the target throttle valve opening is achieved based on the rotation angle, and performs feedback control according to the amount of deviation.

When the magnetic type rotation angle sensor 100 is used for the throttle valve, the magnetic type rotation angle sensor 10 is used.
By taking advantage of the linear output characteristic of 0, accurate engine intake can be performed. Therefore, engine performance is improved.

(Second Embodiment) FIG. 7 is a front view showing the configuration of a magnetic type rotation angle sensor according to a second embodiment of the present invention. FIG. 8 is a side view of the magnetic rotation sensor shown in FIG.

The structure of the magnetic rotation angle sensor 200 is substantially the same as that of the magnetic rotation angle sensor 100, but the linear Hall ICs 24 and 25 are arranged on the outer peripheral upper surface of the cylindrical sleeve 26 at an angle of 180 degrees. Is different.

The sleeve 26 has a structure in which the throttle shaft 11 penetrates, and is attached to the circuit board 27. The material of the sleeve 26 is the magnetic member 19,
It is a high magnetic permeability material such as iron material and magnetic stainless steel material similar to 20. The sleeve 26 has an outer diameter of 12 mm,
The inner diameter is 10 mm. The linear Hall ICs 24, 2
Reference numeral 5 is electrically connected to the circuit board 27.

When the magnetic rotation angle sensor 200 is applied to the throttle valve of the engine, the throttle shaft 11 penetrates the inside of the sleeve 26 and holds the holding member 16.
It is inserted and fixed in the bearing hole 16a.

According to the magnetic type rotation angle sensor 200, since the sleeve 26 concentrates the magnetic flux, the linear Hall IC
The magnetic flux density passing through 24 and 25 increases. For this reason,
A magnetic flux density more than double that of the first embodiment is obtained, and the sensitivity of the magnetic rotation angle sensor 200 is improved.

Further, since the magnetic flux leaked from the magnetic member 19 by the sleeve 26 flows through the sleeve 26 to the magnetic member 20, the magnetic flux hardly leaks inside the sleeve 26. Therefore, even if the throttle shaft 11 penetrates through the sleeve 26, the magnetic rotation angle sensor 2
00 has little effect on the sensitivity.

When the legs of the linear Hall IC are directly attached to the circuit board 27 to fix the linear Hall IC, the distance between the linear Hall IC and the magnetic circuit 15 varies due to external vibration. Therefore, by disposing the linear Hall ICs 24 and 25 on the upper surface of the sleeve 26, the distance between the linear Hall ICs 24 and 25 and the magnetic circuit 15 can be stabilized. Therefore, the sensitivity of the magnetic rotation angle sensor 200 is stable.

Two linear Hall ICs 24 and 25
Is arranged on the upper surface of the sleeve 26 at an angle of 180 degrees.
This is because it is necessary to monitor whether or not a normal output is being output when measuring the throttle valve opening. In such a case, the output signal can be monitored with high accuracy based on the linear output characteristics of the linear Hall ICs 24 and 25.

FIG. 9 is a graph showing changes in the magnitude of the magnetic flux density with respect to the rotation angle θ. When the inventors measured the change in the magnitude of the magnetic flux density of the magnetic rotation angle sensor 200, a linear output characteristic with respect to the rotation angle θ was obtained as shown in the figure. That is, if the magnitude of the magnetic flux density is replaced with the magnitude of the output voltage of the magnetic rotation angle sensor 200, it means that a linear output characteristic is obtained over the entire circumference of 360 degrees.

Further, it has been found that a larger magnetic flux density can be obtained as compared with the case of the first embodiment. Therefore, the sensitivity of the magnetic rotation angle sensor 200 is improved.

[Brief description of drawings]

FIG. 1 is a front configuration diagram showing a magnetic rotation angle sensor according to a first embodiment of the present invention.

FIG. 2 is a side view of the magnetic rotation sensor shown in FIG.

FIG. 3 is an explanatory diagram showing a principle of detecting a rotation angle.

FIG. 4 is a graph showing measurement experimental values of a parallel magnetic field.

FIG. 5 is a graph showing changes in the magnitude of magnetic flux density with respect to a rotation angle θ.

6 is an explanatory diagram showing a case where the magnetic rotation angle sensor shown in FIG. 1 is applied to an electronically controlled throttle valve of an engine.

FIG. 7 is a front configuration diagram showing a magnetic rotation angle sensor according to a second embodiment of the present invention.

8 is a side view of the magnetic rotation sensor shown in FIG. 7. FIG.

FIG. 9 is a graph showing a change in magnitude of magnetic flux density with respect to a rotation angle θ.

FIG. 10 is a configuration diagram showing an example of a conventional magnetic rotation angle sensor.

11 is a graph showing detection characteristics of leakage magnetic flux of the magnetic rotation angle sensor shown in FIG.

[Explanation of symbols]

 100 Magnetic Rotation Sensor 15 Magnetic Circuit 16 Holder 16a Bearing Hole 17,18 Magnet 19,20 Magnetic Member 21 Linear Hall IC 22 Circuit Board 200 Magnetic Rotation Angle Sensor 24,25 Linear Hall IC 27 Circuit Board

Claims (5)

[Claims] 1. A parallel magnetic field in a specific direction is uniformly generated in the internal space of the magnetic circuit, and the magnetic sensor is rotated in the internal space of the magnetic circuit so that the relative angle between the magnetic sensor and the magnetic circuit is non-contact. Magnetic rotation angle sensor characterized by measuring. 2. A magnet having two pillar-shaped magnets and two pillar-shaped magnetic members, and S of the two magnets.
A magnetic circuit having a structure in which poles are connected by the one magnetic member, and N poles of the magnet are connected by the other magnetic member; and a parallel magnetic field plane in a specific direction formed by the magnetic circuit. A magnetic sensor having a vertical rotation axis at the center of the magnetic circuit, and arranged at a predetermined distance from the rotation axis, and rotating the magnetic sensor about the rotation axis, A magnetic rotation angle sensor, which measures a relative angle between the magnetic circuit and the magnetic sensor in a non-contact manner. 3. The magnetic rotation angle sensor according to claim 2, wherein the internal space of the magnetic circuit has a substantially square shape. 4. The magnetic rotation angle sensor according to claim 2, wherein a magnetic member is provided around the rotation shaft, and the magnetic sensor is arranged on the magnetic member. Rotation angle sensor. 5. The magnetic rotation angle sensor according to any one of claims 2 to 4, wherein two magnetic sensors are arranged facing each other around the rotation axis. .