JP2001133286A - Revolution detection sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a revolution detection sensor capable of reducing the weight of a revolution member and reducing the load on a rotor. SOLUTION: In the outermost periphery of a revolution plate 2 of the revolution detection sensor, magnetic path changing pieces 18a, 18b and 18c are extended and formed. A magnetic detector member 3 are arranged in the diameter outward direction of the revolution plate of the magnetic path changing pieces 18a, 18b and 18c. A detector body 10 is constituted of the first to the third magnetic detectors 13, 14 and 15. The first to the third magnetic detectors 13 to 15 are constituted respectively of the first to the third magnetic resistor elements 13a to 15a and the first to the third bias magnets 13b to 15b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation detection sensor and, more particularly, to a rotation detection sensor using a magnet.

[0002]

2. Description of the Related Art The present applicant has proposed a rotation detecting sensor shown in FIGS. 10 and 11 for detecting the rotation of a rotating body. The rotation detection sensor 1 shown in FIG. 1 detects a rotation angle of a motor shaft of a motor, and includes a rotation plate 2 as a rotation member made of an iron plate and a magnetic detection member 3. The rotating plate 2 rotates about its axis O with the rotation of the motor shaft 4 as the center of rotation. As shown in FIG. 11, three arc-shaped magnetic path changing pieces 6 a to 6 c centering on the axis O extend from the rotating plate 2 at the outermost peripheral portion in the rotation plane of the rotating plate 2. Is formed. The interval between the magnetic path changing pieces 6a to 6c is set at an angle of 60 degrees with respect to the axis O. Therefore, at the outermost periphery in the rotation plane of the rotating plate 2, as viewed from the axis O,
For each degree angle, these magnetic path changing pieces 6a to 6c and the spaces 7a to 7 where these magnetic path changing pieces 6a to 6c are not formed.
c are alternately present.

At the center of the rotary plate 2, a columnar magnetic path forming projection 8 as a magnetic path changing piece is provided with the magnetic path changing pieces 6a to 6a.
It extends from the rotary plate 2 in the same direction as c. Therefore, when the rotating plate 2 is cut from the magnetic path changing pieces 6a to 6c toward the axis O, the cross-sectional shape is the magnetic path changing pieces 6a to 6c.
c, the rotating plate 2 and the magnetic path forming projection 8 form a U-shape.

A through hole 9 is formed in the magnetic path forming projection 8, and the motor shaft 4 is inserted and fixed. The magnetic detecting member 3 includes a main body 10 and a support arm 11. As shown in FIG.
Are disposed inside the magnetic path changing pieces 6a to 6c formed on the rotating plate 2 and in a space located between the magnetic path changing pieces 6a to 6c and the magnetic path forming projections 8. The detection unit main body 10 is configured by sealing a plurality of magnetic detectors 13 to 15 with a resin mold material 12. Each magnetic detector 13
15 are bias magnets 13b arranged opposite to the rotating plate 2 and arranged in a predetermined direction.
15b and magnetoresistive elements 13a to 15a for detecting magnetic fluxes of the bias magnets 13b to 15b.
When the magnetic path changing pieces 6a to 6c that move together with the rotating rotating plate 2 pass through the positions corresponding to the respective magnetic detectors 13, the direction of the magnetic flux of the bias magnet 13b is changed. The change is detected by the magnetoresistive elements 13a to 15a.

[0005]

However, the rotation detecting sensor 1 uses the bias magnets 13b to 13b at the detecting points.
Magnetic path changing pieces 6a to 6c and magnetic path forming projections 8 are provided on both inside and outside of the detection unit main body 10 so that the direction of the magnetic flux 15b changes greatly. Therefore, the mass of the rotating plate 2 becomes large. Therefore, for example, when this rotation detection sensor 1 is used to detect the rotation of the motor shaft, a load is applied to the motor because the mass of the rotating plate 2 is large, and moreover,
When the motor is rotated at a high speed, the air resistance of the magnetic path changing pieces 6a to 6c increases, so that there is a problem that current consumption increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and an object of the present invention is to provide a rotation detecting sensor capable of reducing the weight of a rotating member and reducing the load on a rotating body. It is in.

[0007]

According to a first aspect of the present invention, there is provided a rotating member having a plurality of magnetic path changing pieces erected at predetermined intervals around a center of rotation of a rotating surface; In a rotation detection sensor comprising a magnet disposed in a predetermined direction and a magnetic detection element for detecting the magnet, the magnetic path changing piece is radially inward of a rotating surface with respect to the magnetic detection element or The gist of the present invention is a rotation detection sensor provided only on one of the outer sides.

According to a second aspect of the present invention, in the rotation detecting sensor according to the first aspect, the magnetic path changing piece has a boss disposed around a rotation shaft attached to a rotation center of the rotation member. The gist of the present invention is a rotation detection sensor that is also used as the rotation detection sensor.

According to a third aspect of the present invention, in the rotation detecting sensor according to the first aspect, the magnetic path changing piece is arranged close to a boss attached to the center of rotation of the rotating member. The gist is a sensor.

(Operation) According to the first aspect of the present invention,
When the magnetic path changing piece of the rotating member is arranged only radially inward of the rotating surface from the magnetic sensing element, unlike the conventional configuration of FIGS. 10 and 11, there is no need to make the rotating plate large, Therefore, the rotating member is made compact.

In the case where the magnetic path changing piece of the rotating member is arranged only radially outside the rotating surface from the magnetic sensing element,
Unlike the conventional configurations shown in FIGS. 10 and 11, there is no need to provide a magnetic path changing piece on the boss side, so that the diameter of the rotating plate can be reduced accordingly, and the rotating member can be made compact. .

As described above, when the rotating member itself is made compact, the weight can be reduced, and even when the rotating member is rotated at a high speed, the air resistance of the magnetic path changing piece does not increase.

According to the second aspect of the present invention, the magnetic path changing piece is also used as a boss disposed around the rotation shaft attached to the rotation center of the rotation member. There is no need to provide it separately. Therefore, the weight of the rotating member can be reduced.

According to the third aspect of the invention, when the magnetic path changing piece is disposed close to the boss attached to the center of rotation of the rotating member, the rotating member can be made compact and the weight of the rotating member can be reduced. be able to.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 4 show an embodiment in which the present invention is embodied in a rotational position sensor.
It will be described according to. Note that the same reference numerals are given to components corresponding to the above-described conventional embodiment.

FIG. 1 is an exploded perspective view of a main part of the rotational position sensor. Rotational position sensor 100 as rotation detection sensor
Is composed of a rotating plate 2 as a rotating member made of an iron plate and a magnetic detecting member 3.

The rotary plate 2 is attached to the motor shaft 4 of the motor through its boss 17 and rotates about its axis O with the rotation of the motor shaft 4. The boss 17 has a through hole 9 through which the motor shaft 4 is inserted and fixed. Three magnetic path changing pieces 18a, 18b, 18c are provided on the outermost peripheral portion of the rotary plate 2.

That is, as shown in FIG. 2, the magnetic path changing pieces 18a, 18b, and 18c are positioned at a position slightly separated from the axis O with respect to the rotation surface of the rotary plate 2 and the boss portion 17. It is formed so as to extend in an arc-shaped cross section centering on the axis O. The magnetic path changing pieces 18a, 18b, 18c
The one end to the other end are formed so as to form an angle of 60 degrees with respect to the axis O. Also, each magnetic path changing piece 18a,
The interval formed between 18b and 18c is formed so as to form an angle of 60 degrees with respect to the axis O.

Accordingly, at the outermost peripheral portion in the plane of the rotating plate 2, these magnetic path changing pieces 18a, 18b, 18c and the magnetic path changing pieces 18 are provided at every 60 degrees from the axis O.
spaces 19a, 1 in which no a, 18b, 18c is formed
9b and 19c are alternately present.

The detection unit main body 10 of the magnetic detection member 3 includes:
It is arranged outside the magnetic path changing pieces 18, 18b, 18c formed on the rotating plate 2. The detection unit main body 10 includes three first to third magnetic detectors 13, 14, and 15 sealed with a resin mold material 12 and fixed to a distal end of the support arm 11. The base end of the support arm 11 is fixed to a fixing member (not shown). The first magnetic detector 13 is
It comprises a first magnetoresistive element 13a as a magnetic sensing element and a first bias magnet 13b as a magnet. The first bias magnet 13b is disposed so that the axial center O side is an N pole and the outer side is an S pole, and the first bias magnet 13b is on the axial center O side with respect to the first magnetoresistive element 13a and in a clockwise direction in FIG. They are arranged offset.

The first magnetoresistive element 13a is a magnetoresistive element whose detection voltage changes according to the direction of the magnetic flux of the first bias magnet 13b, and its resistance value changes according to the direction of the magnetic flux as shown in FIG. Four resistors R1,
R2, R3, and R4 are provided. Two resistors R1, R
Four groups are arranged toward the same arrangement direction, and two groups are arranged.
The group of the resistors R2 and R3 are the resistors R1 and R3.
4 are arranged in an arrangement direction orthogonal to the arrangement direction.

The change range of the direction of the magnetic flux in this embodiment is as follows.
The range from when the direction of the magnetic flux is at a predetermined angle counterclockwise with respect to the substantially radial direction from the axis O to when the direction of the magnetic flux is at a predetermined angle clockwise with respect to the substantially radial direction. .

Each of the resistors R1 to R4 is formed by forming a Ni—CO thin film on the substrate in a zigzag shape, that is, in a polygonal line shape. The resistors R1 to R4 are set to have the same resistance under the same temperature atmosphere. The resistors R1 to R4 have sensitivity temperature characteristics in which the sensitivity changes when the ambient temperature increases. In this sensitivity temperature characteristic, it is preferable that the rate of change in sensitivity temperature and the rate of change in resistance temperature match.

When the direction of the magnetic flux is at a predetermined angle in the counterclockwise direction from the axis O with respect to the substantially radial direction, the resistances R1 and R4 are in the first state in which the resistance value increases. At the same time, the resistors R2 and R3 are arranged so as to be in the second state where the resistance value is small, and when the direction of the magnetic flux is at a predetermined angle clockwise with respect to the substantially radial direction, the resistor R1 , R4 are arranged in a second state in which the resistance value decreases, and the resistors R2, R3 are arranged in a first state in which the resistance value increases. Therefore, these states occur alternately in response to changes in magnetic flux.

The resistors R1 to R4 are connected so as to form a four-terminal bridge circuit B as a bridge circuit as shown in FIG. A connection point (middle point) a between the resistors R and R2 is connected to a non-inverting input terminal of a comparator CP provided on the substrate, and a connection point (middle point) b between the resistors R3 and R4 is the same. It is connected to the inverting input terminal of the comparator CP.

The comparator CP and the four-terminal bridge circuit B constitute a detection circuit DC. Resistors R1 and R4 forming a bridge circuit B of the detection circuit DC
When the direction of the magnetic flux is at a predetermined angle in the counterclockwise direction from the axis O with respect to the substantially radial direction, the potential at the midpoint a becomes the L level smaller than the reference voltage at the midpoint b. .

When the direction of the magnetic flux forms a predetermined angle in the clockwise direction with respect to the substantially radial direction, the midpoint a
Is higher than the reference voltage at the middle point b. Note that the detection point P in the present embodiment is an edge portion in the rotation direction of the magnetic path changing pieces 18a, 18b, 18c during movement (rotation).

The second magnetic sensing element 14 includes a second magnetoresistive element 14a as a magnetic sensing element and a second bias magnet 14b as a magnet. The positional relationship between the second magnetoresistive element 14a and the second bias magnet 14b is the same as the positional relationship between the first magnetoresistive element 13a and the first bias magnet 13b. Then, the second magnetoresistive element 14a and the second bias magnet 14b are respectively different from the first magnetoresistive element 13a and the first bias magnet 13b in FIG.
It is disposed at a position of 40 degrees clockwise about the axis O.

The second magnetoresistive element 14a includes a second bias magnet 14b similar to the first magnetoresistive element 13a.
Is a magnetic sensing element whose detection voltage changes according to the direction of the magnetic flux, and has four resistors R1 to R4 as shown in FIG. 4, and operates in the same manner as the first magnetoresistive element 13a.

The resistances R1 to R1 of the second magnetoresistive element 14a are
R4 forms a 4-terminal bridge circuit similar to that of the first magnetoresistive element 13a. Further, the second magnetoresistive element 1
The resistors R1 to R4 of 4a, together with the comparator CP,
The detection circuit DC is configured. The function of the detection circuit DC and the function of the bridge circuit B are the same as those of the detection circuit DC in the case of the first magnetoresistive element 13a.

The third magnetic detector 15 includes a third magnetoresistive element 15a as a magnetic detecting element and a third bias magnet 15b as a magnet. The positional relationship between the third magnetoresistive element 15a and the third bias magnet 15b is the same as the positional relationship between the first magnetoresistive element 13a and the first bias magnet 13b. The third magnetoresistive element 15a and the third bias magnet 15b are different from the first magnetoresistive element 13a and the first bias magnet 13b in FIG.
It is disposed at a position of 40 degrees counterclockwise about the axis O.

The third magnetoresistive element 15a includes a third bias magnet 15b similar to the first magnetoresistive element 13a.
Is a magnetic sensing element whose detection voltage changes according to the direction of the magnetic flux, and has four resistors R1 to R4 as shown in FIG. 4, and operates in the same manner as the first magnetoresistive element 13a.

The resistances R1-R3 of the third magnetoresistive element 15a
R4 forms a four-terminal bridge circuit as in the case of the first magnetoresistive element 13a. Further, the third magnetoresistive element 1
The resistors R1 to R4 of 5a, together with the comparator CP,
The detection circuit DC is configured. This DC function of the detection circuit functions (works) in the same manner as the detection circuit 20 in the case of the first magnetoresistive element 13a.

Now, the operation of the rotational position sensor 100 configured as described above will be described. In the relative positional relationship between the first to third bias magnets 13b to 15b and the magnetic path changing pieces 18a to 18c, each of the first to third bias magnets 13b to 15b is positioned at the position of the third bias magnet 15b shown in FIG. , That is, when any of the magnetic path changing pieces 18a to 18c is located on the radiation passing from the axis O to the N pole (hereinafter referred to as the inside), the magnetic fluxes thereof are substantially in the radial direction. On the other hand, the direction becomes a predetermined angle in the counterclockwise direction.

The magnetic path changing pieces 18a to 18c and the magnetic path passing through the rotary plate 2 are formed, and the magnetic flux is transmitted from the N poles of the first to third bias magnets 13b to 15b. Because they are attracted to As a result, the direction of the magnetic flux is a direction forming a predetermined angle in the counterclockwise direction with respect to the magnetic path changing pieces 18a to 18c, that is, the substantially radial direction. That is, the magnetic path changing pieces 18a to 18c are magnetic path forming pieces.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B becomes L level. Further, the first to third bias magnets 13b to 15b and the magnetic path changing pieces 18a to 1
8c, when each of the first to third bias magnets 13b to 15b is located at the position of the second bias magnet 14b shown in FIG.
When the magnetic path changing pieces 18a to 18c are not located inside the poles, the magnetic fluxes are oriented at a predetermined angle clockwise with respect to the substantially radial direction. This is because there is no magnetic path changing piece 18a to 18c that forms a magnetic path, so that no magnetic flux is drawn. As a result, the magnetic flux extends radially, and the direction of the magnetic flux is at a predetermined angle clockwise with respect to the substantially radial direction.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B becomes H level. Furthermore, the first to third
Bias magnets 13b to 15b and magnetic path changing piece 18a
In the relative positional relationship with the first to third bias magnets 13b to 15c, the first to third bias magnets 13b to 15b
The magnetic path changing pieces 18a to 18c are located at the positions of the bias magnets 13b and have no magnetic path changing pieces 18a to 18c.
When the magnetic flux passes through end c, the direction of the magnetic flux changes from a direction forming a predetermined angle clockwise to the substantially radial direction, to a direction forming a predetermined angle counterclockwise to the substantially radial direction.

Therefore, in this case, the middle point a of the four-terminal bridge circuit B outputs a voltage that falls from the H level to the L level. Further, when the magnetic path changing pieces 18a to 18c pass through the ends from a certain position, the directions of the magnetic fluxes are changed from a direction forming a predetermined angle in a counterclockwise direction with respect to the substantially radial direction, and are changed in a clockwise direction with respect to the substantially radial direction. It changes to a direction that forms a predetermined angle in the circumferential direction.

Accordingly, in this case, the middle point a of the four-terminal bridge circuit B outputs a voltage that rises from the L level to the H level and rises four times. Thus, the four-terminal bridge circuit B
The potential at the middle point a becomes H level and L level, and the comparator CP of the detection circuit DC shapes the waveform into a detection signal having a sharp fall based on the middle point b on the side that becomes the reference voltage (threshold voltage). You.

Next, the features of the rotational position sensor 100 configured as described above will be described. (1) In the present embodiment, the first to third magnetoresistive elements 13a
To 15a and the first to third bias magnets 13b to 15b
The detection unit main body 10 made of b is disposed radially outward of the rotating surface of the rotating plate 2, that is, disposed only outside the magnetic path changing pieces 18a to 18c.

As a result, the magnetic path changing pieces 18a to 18c
Since it is arranged radially inward of the magnetic detection member 3, it is located on the center side of the rotating plate 2. Accordingly, the rotating plate 2 (rotating member) itself is made compact, and the rotating plate 2
The magnetic path changing pieces 18a, 18b, 18c of the magnetic detecting member 3
Thus, the weight can be reduced as compared with the case where it is arranged radially outside. Even when the rotating plate 2 is rotated at a high speed, the magnetic path changing pieces 18a, 18b and 18c of the rotating plate 2 are arranged more radially outward than the magnetic detecting member 3 in comparison with the magnetic path changing pieces 18a and 18c.
The air resistance of 18b and 18c does not increase.

Therefore, when the rotary plate 2 is attached to the motor shaft 4, the rotational load of the motor can be reduced and does not increase. (2) In the present embodiment, the detection unit main body 10 is disposed radially outward of the rotation surface of the rotating plate 2, so that the rotation position sensor does not increase in size.

(3) In the present embodiment, the magnetic path changing piece 18a
Since 18c are formed integrally with the rotating plate 2, the number of components does not increase, and the number of assembling steps does not increase. (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

For convenience of explanation, the same reference numerals are used for members common to those in the first embodiment, and detailed description thereof is omitted. As shown in FIG. 5 and FIG.
0, the magnetic path changing piece 18a in the configuration of the first embodiment.
18c are omitted, and magnetic path changing pieces 36a, 3 each having a fan-shaped cross section from the motor shaft 4 to the outermost peripheral portion are provided on the rotating plate 2.
6b and 36c are formed. Magnetic path changing pieces 36a, 3
6b and 36c are formed so that one end to the other end forms an angle of 60 degrees when viewed from the axis. The interval between the magnetic path changing pieces 36a, 36b, 36c is
It is formed so as to form an angle of 60 degrees from the axis.

Accordingly, at the inner peripheral portion in the plane of the rotary plate 2, these magnetic path changing pieces 36a, 36b, 36c and these magnetic path changing pieces 36a, 36a,
Spaces 37a and 37 in which 36b and 36c are not formed
b and 37c are present alternately. The inner peripheral surfaces of the magnetic path changing pieces 36a, 36b, 36c are in contact with the motor shaft 4, and accordingly, the magnetic path changing pieces 36a, 36b, 36c are in contact with each other.
Reference numerals 36b and 36c also serve as bosses of the rotating plate 22.

The magnetic detecting member 43 is composed of a detecting section main body 44 and the support arm 11. Detector body 44
Are magnetic path changing pieces 36a, 36b, 3 formed on the rotating plate 2.
6c.

The detection unit main body 44 has three first to third magnetic detectors 45, 46, 47 sealed with a resin mold material 12, and is fixed to the tip of the support arm 11. . The first magnetic detector 45 includes a first magnetic resistance element 45a as a magnetic detection element and a first bias magnet 45b as a magnet. The first bias magnet 45b is disposed so that the axis O side is the N pole and the outside is the S pole, and is disposed outside the first magnetoresistive element 45a and offset clockwise in FIG. Have been.

The first magnetoresistive element 45a is a magnetoresistive element whose detection voltage changes according to the direction of the magnetic flux of the first bias magnet 45b, and its resistance value changes according to the direction of the magnetic flux as shown in FIG. Four resistors R1, R
2, R3 and R4. The group of the two resistors R1 and R4 is arranged in the same arrangement direction,
The groups R2 and R3 are arranged in an arrangement direction orthogonal to the arrangement direction of the resistors R1 and R4.

The change range of the direction of the magnetic flux in this embodiment is as follows.
As in the first embodiment, when the direction of the magnetic flux is at a predetermined angle counterclockwise from the axis O with respect to the substantially radial direction, the magnetic flux is directed at a predetermined angle clockwise with respect to the substantially radial direction. It is up to the range when it becomes. Also, each of the resistors R1 to R
The configuration and arrangement of 4 are also provided in the same manner as in the first embodiment. Each of the resistors R1 to R4 forms a four-terminal bridge circuit B as a bridge circuit as shown in FIG. 4, and a connection point (middle point) a between the resistors R1 and R2.
Is connected to the non-inverting input terminal of the comparator CP as in the first embodiment, and a connection point (middle point) b between the resistors R3 and R4 is connected to the inverting input terminal of the comparator CP.

The detection point P in the present embodiment is an edge portion in the rotation direction of the magnetic path changing pieces 36a, 36b, 36c during movement (rotation). The second magnetic detector 46 is
It is composed of a second magnetic resistance element 46a as a magnetic sensing element and a second bias magnet 46b as a magnet. The positional relationship between the second magnetoresistive element 46a and the second bias magnet 46b depends on the first magnetoresistive element 4a.
This is the same as the arrangement relationship between 5a and the first bias magnet 45b. Then, the second magnetoresistive element 46a and the second
The bias magnet 46b is disposed at a position 40 degrees clockwise about the axis O in FIG. 6 with respect to the first magnetoresistive element 45a and the first bias magnet 45b, respectively.

The second magnetoresistive element 46a includes a second bias magnet 46b similar to the first magnetoresistive element 45a.
A magnetoresistive element whose detection voltage changes according to the direction of the magnetic flux, and which includes four resistors R1 to R4 whose resistance values change according to the direction of the magnetic flux as shown in FIG. It is configured and arranged similarly to the body 45a and performs the same action.

The resistances R1 to R1 of the second magnetoresistive element 46a are
R4 forms a four-terminal bridge circuit similar to that of the first magnetoresistive element 45a. Further, the second magnetoresistive element 4
The resistors R1 to R4 of 6a, together with the comparator CP,
The detection circuit DC is configured. The operation of the detection circuit DC and the bridge circuit B functions (works) in the same manner as the detection circuit DC in the case of the first magnetic resistance element 45a.

The third magnetic sensing element 47 includes a third magnetic resistance element 47a as a magnetic sensing element and a third bias magnet 47b as a magnet. The positional relationship between the third magnetic resistance element 47a and the third bias magnet 47b is the same as the positional relation between the first magnetic resistance element 45a and the first bias magnet 45b. In addition, the third magnetoresistive element 47a and the third bias magnet 47b are respectively rotated counterclockwise about the axis O in FIG. 6 with respect to the first magnetoresistive element 45a and the first bias magnet 45b. It is arranged at a position of 40 degrees in the direction.

The third magnetoresistive element 47a is a magnetoresistive element whose detection voltage changes according to the direction of the magnetic flux of the third bias magnet 47b, like the first magnetoresistive element 45a. Are provided in the same manner as the first magnetic resistor 45a, and perform the same operation.

The resistances R1 to R3 of the third magnetoresistive element 47a are
R4 forms a four-terminal bridge circuit similar to that of the first magnetoresistive element 45a. Further, the third magnetoresistive element 4
The resistors R1 to R4 of 7a, together with the comparator CP,
The detection circuit DC is configured. The operation of the detection circuit DC and the bridge circuit B functions (works) in the same manner as the detection circuit DC in the case of the first magnetic resistance element 45a.

Now, the operation of the rotational position sensor 40 configured as described above will be described. When the first to third bias magnets 45b to 47b are located at the position of the third bias magnet 47b shown in FIG. 6, that is, when any of the magnetic path changing pieces 36a to 36c is located in front of the N pole. Are the first to third bias magnets 47b to 47b.
The direction of the magnetic flux b is such that the magnetic flux forms a predetermined angle counterclockwise with respect to the substantially radial direction. This is the first to third
This is because the magnetic flux is drawn from the N poles of the bias magnets 45b to 47b to the magnetic path changing pieces 36a to 36c.
As a result, the direction of the magnetic flux is changed to the magnetic path changing pieces 36a to 36c.
Side, that is, a direction making a predetermined angle counterclockwise with respect to the substantially radial direction.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B becomes L level. Also, the first to third bias magnets 45b to 47b and the magnetic path changing pieces 36a to 3
6c, when the first to third bias magnets 45b to 47b are located at the position of the second bias magnet 46b shown in FIG. 6, that is, in front of the N pole, the magnetic path changing pieces 36a to 36c If is not located,
The magnetic fluxes of the first to third bias magnets 45b to 47b are oriented at a predetermined angle clockwise with respect to the radial direction. This is a magnetic path changing piece 36a that forms a magnetic path.
This is because there is no ~ 36c, and no magnetic flux is drawn. As a result, the magnetic flux extends radially, and the direction of the magnetic flux is at a predetermined angle clockwise with respect to the substantially radial direction.

Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B becomes H level. Furthermore, the first to third
Bias magnets 45b-47b and magnetic path changing piece 36a
6 to 36c, the first to third bias magnets 45b to 47b correspond to the first bias magnets 45b to 47b shown in FIG.
When the ends of the magnetic path changing pieces 36a to 36c pass from the position where the magnetic path changing pieces 36a to 36c do not exist in front of the N pole at the position of the bias magnet 45b,
The direction of the magnetic flux of the third bias magnets 45b to 47b changes from a direction making a predetermined angle clockwise with respect to the substantially radial direction, to a direction making a predetermined angle counterclockwise with respect to the substantially radial direction.

Therefore, in this case, the middle point a of the four-terminal bridge circuit B outputs a voltage that falls from the H level to the L level. Further, the first to third magnetoresistive elements 45a to 45a
When the ends of the magnetic path changing pieces 36a to 36c pass from the position where the magnetic path changing pieces 36a to 36c are located in front of 47a,
The direction of the magnetic flux of the first to third bias magnets 45b to 47b changes from a direction forming a predetermined angle in a counterclockwise direction with respect to the substantially radial direction, to a direction forming a predetermined angle in a clockwise direction with respect to the substantially radial direction. change.

Accordingly, in this case, the middle point a of the four-terminal bridge circuit B outputs a voltage rising from the L level to the H level. In this way, the potential at the middle point a of the four-terminal bridge circuit B becomes H level and L level, and the reference voltage (threshold voltage) is obtained by the comparator CP of the detection circuit DC.
The waveform is shaped into a detection signal having a sharp fall based on the middle point b on the side where

Next, the features of the rotational position sensor 40 configured as described above will be described. (1) In the present embodiment, a small-diameter rotary plate 2 is used, and magnetic path changing pieces 36a, 36b, 36c from the motor shaft 4 to the outermost peripheral portion are formed on the rotary plate 2, and the rotary plate 2 The magnetic detection member 43 was arranged on the outer periphery.

Therefore, the rotating plate 2 of the present embodiment can be reduced in mass as compared with the conventional rotating plate 2. Therefore, for example, when the rotation position sensor 40 is used to detect the rotation of the motor shaft 4, it is possible to reduce the load on the motor and suppress an increase in current consumption.

(Third Embodiment) Next, a rotation position sensor 200 as a rotation detecting sensor according to a third embodiment will be described with reference to FIGS. In this embodiment, FIG.
11 is a modification of the conventional configuration shown in FIG. 11, and the same components as those of the conventional configuration are denoted by the same reference numerals, and only different portions are omitted.

In this embodiment, as shown in FIGS. 8 and 9, the magnetic path forming projection 8 is omitted, and the rotating plate 2 is integrally fixed to the motor shaft 4. Therefore, in this embodiment,
When the rotary plate 2 is cut from the magnetic path changing pieces 6a to 6c toward the axis O, the cross-sectional shape is an L shape with the magnetic path changing pieces 6a to 6c and the rotary plate 2.

That is, in this embodiment, the plurality of magnetic path changing pieces 6a to 6
c, a rotating position including a rotating plate 2 having an erect position, and bias magnets 13b to 15b arranged in a predetermined direction with respect to the rotating plate 2 and magnetoresistive elements 13a to 15a for detecting the bias magnets 13b to 15b. The sensor was configured. Then, the magnetic path changing pieces 6a to 6c are
With respect to 3a to 15a, they are arranged only on the radially outer side of the rotating surface.

As a result, in the present embodiment, the diameter of the rotating plate 2 can be reduced by an amount corresponding to the omission of the magnetic path forming projections 8, and as a result, the size and weight can be reduced. Note that the embodiments are not limited to the embodiments described above, and may be modified as follows.

In the above embodiment, the magnetic path changing piece 18a
18c, 36a to 36c are arranged such that one end to the other end forms an angle of 60 degrees with respect to the axis O, that is, 6
0 degree intervals, and the respective magnetic detectors 13, 14, 15
The interval was set at 40 degrees. Instead, the magnetic path changing pieces 18a to 18c and 36a to 36c may be set at intervals of 30 degrees, and the intervals between the magnetic detectors 13, 14, and 15 may be set at intervals of 20 degrees. This makes it possible to detect a smaller angle than in each embodiment.

[0068]

As described in detail above, according to the first to third aspects of the present invention, the weight of the rotating member can be reduced, and the load on the rotating body can be reduced.

According to the second aspect of the present invention, since the magnetic path changing piece is also used as a boss arranged around the rotation shaft attached to the rotation center of the rotation member, the boss is separately provided. , It is possible to reduce the weight of the rotating member.

According to the third aspect of the present invention, since the magnetic path changing piece is arranged close to the boss attached to the rotation center of the rotating member, the rotating member can be made compact.
The weight of the rotating member can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a rotation position sensor according to a first embodiment.

FIG. 2 is a plan view showing an arrangement relationship between a rotating plate and a magnetic detection member.

FIG. 3 is a sectional view of a main part of the rotation position sensor.

FIG. 4 is an equivalent circuit diagram of a magnetoresistive element.

FIG. 5 is an exploded perspective view of a main part of a rotation position sensor for describing a second embodiment.

FIG. 6 is a plan view showing an arrangement relationship between a rotating plate and a magnetic detection member.

FIG. 7 is a sectional view of a principal part of the rotation position sensor.

FIG. 8 is an exploded perspective view of a main part of a rotation position sensor for describing a third embodiment.

FIG. 9 is a plan view showing an arrangement relationship between the rotating plate and the magnetic detection member.

FIG. 10 is an exploded perspective view of a main part of a conventional rotation position sensor proposed by the applicant.

FIG. 11 is a plan view showing an arrangement relationship between a rotating plate and a magnetic detection member.

[Explanation of symbols]

Reference numerals 40, 100, 200: a rotation position sensor as a rotation detection sensor, 2: a rotating plate 3, a magnetic detection member, 4 ... a motor shaft as a rotating body, 6a to 6c, 18a to 18c, 36a
36c: magnetic path changing piece, 19a to 19c: space, 9: through hole, 10: detecting body, 11: support arm, 12: resin mold material, 13, 45: first magnetic detector, 14,
46: second magnetic detector, 15, 47: third magnetic detector, 13a, 45a: first magnetoresistive element, 13b, 45
b: first bias magnet, 14a, 46a: second magnetic resistance element, 14b, 46b: second bias magnet, 15a, 47a: third magnetic resistance element, 15b, 47
b: third bias magnet, Vout: detection voltage, R
1 to R4: resistor.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Taniguchi 3-260 Toyota, Oguchi-cho, Niwa-gun, Aichi Prefecture Inside Tokai Rika Electric Machinery Works, Ltd. F term in NW Corporation (reference) 2F063 AA35 CA29 CA34 DA06 EA03 GA52 GA69 GA73 KA04 LA27 ZA06 2F077 AA42 AA43 JJ02 JJ10 JJ21 NN04 NN07 NN22 PP15 QQ02 TT16 VV02 VV09

Claims (3)

[Claims] A plurality of magnetic path changing pieces (18a-18c, 36a-36) are provided at predetermined intervals around a rotation center of a rotation surface.
a rotating member (2) on which the c) is erected, and the rotating member (2)
Magnets (13b to 15b)
b, 45b to 47b) and the magnets (13b to 15b, 45b).
b to 47b) (13a to 15b)
a, 45a to 47a), wherein the magnetic path changing pieces (18a to 18c, 36a to 36c)
With the magnetic sensing elements (13a to 15a, 45a to 47
a) a rotation detection sensor disposed only on either the inside or outside in the radial direction of the rotation surface with respect to a). 2. The magnetic path changing piece according to claim 1, wherein the magnetic path changing piece also serves as a boss disposed around a rotation shaft attached to a rotation center of the rotation member. Rotation detection sensor. 3. The rotation detecting sensor according to claim 1, wherein the magnetic path changing piece is disposed close to a boss attached to a rotation center of the rotating member.