JP3710973B2 - Rotation detection sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation detection sensor and, more particularly, to a rotation detection sensor using a magnet.
[0002]
[Prior art]
The present applicant has proposed a rotation detection sensor shown in FIGS. 10 and 11 for detecting the rotation of the rotating body. A 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 and a magnetic detection member 3 as a rotation member made of an iron plate. The rotating plate 2 rotates about its axis O as the motor shaft 4 rotates. 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 rotating surface of the rotating plate 2. Is formed. The interval between the magnetic path changing pieces 6a to 6c is set to an angle of 60 degrees when viewed from the axis O. Therefore, these magnetic path changing pieces 6a to 6c and the magnetic path changing pieces 6a to 6c are not formed at every 60 degrees from the axis O in the outermost peripheral portion in the rotating surface of the rotating plate 2. Spaces 7a to 7c exist alternately.
[0003]
Further, a cylindrical magnetic path forming convex portion 8 as a magnetic path changing piece is formed at the center of the rotating plate 2 so as to extend from the rotating plate 2 in the same direction as the magnetic path changing pieces 6a to 6c.
Therefore, the cross-sectional shape when the rotating plate 2 is cut from the magnetic path changing pieces 6a to 6c toward the axis O is the same as that of the magnetic path changing pieces 6a to 6c, the rotating plate 2 and the magnetic path forming convex portion 8. It becomes a letter shape.
[0004]
A through hole 9 is formed in the magnetic path forming convex portion 8, and the motor shaft 4 is fixedly inserted therethrough.
The magnetic detection member 3 includes a detection unit main body 10 and a support arm 11. As shown in FIG. 11, the detection unit main body 10 is inside the magnetic path changing pieces 6 a to 6 c formed on the rotating plate 2 and between the magnetic path changing pieces 6 a to 6 c and the magnetic path forming convex part 8. It is arrange | positioned in the space located in. The detection unit main body 10 is configured by sealing a plurality of magnetic detection bodies 13 to 15 with a resin mold material 12. Each of the magnetic detectors 13 to 15 is arranged to face the rotating plate 2 and is arranged in a predetermined direction, and a magnetoresistive element for detecting the magnetic flux of the bias magnets 13b to 15b. 13a-15a. In the rotation detection sensor 1, the direction of the magnetic flux of the bias magnet 13 b is changed when the magnetic path changing pieces 6 a to 6 c that move together with the rotating rotating plate 2 pass through positions corresponding to the magnetic detection bodies 13. The change is detected by the magnetoresistive elements 13a to 15a.
[0005]
[Problems to be solved by the invention]
However, the rotation detection sensor 1 has the magnetic path changing pieces 6a to 6c and the magnetic path forming convex portions 8 on both the inner and outer sides of the detection unit main body 10 so that the direction of the magnetic flux of the bias magnets 13b to 15b changes greatly at the detection point. Provided. Therefore, the mass of the rotating plate 2 is 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 the magnetic path changing pieces 6a to 6c of the magnetic path changing pieces 6a to 6c are rotated at high speed. Since the air resistance increases, there is a problem that current consumption increases.
[0006]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a rotation detection sensor capable of reducing the weight of the rotating member and reducing the load on the rotating body.
[0007]
[Means for Solving the Problems]
The invention described in claim 1 A rotating member, a rotating body attached to the rotation center of the rotating member, and the rotating member Predetermined spacing around the center of rotation of the rotating surface In the axial direction of the rotating body Multiple magnetic path change pieces When A magnet disposed in a predetermined direction with respect to the rotating member; , The magnet Magnetic flux In the rotation detection sensor comprising a magnetic sensing element for detecting the magnetic sensing element, the magnetic path changing piece is located within the radial direction of the rotating surface with respect to the magnetic sensing element. On the side Only arranged And the surface of the magnetic path changing piece on the rotating body side is brought into contact with the rotating body. The gist is a rotation detection sensor.
[0008]
According to a second aspect of the present invention, there is provided a rotating member in which a plurality of magnetic path changing pieces are erected at predetermined intervals around the rotation center of the rotating surface, and a magnet arranged in a predetermined direction with respect to the rotating member. In a rotation detection sensor comprising a magnetic sensing element for detecting the magnet, the magnetic path changing piece is disposed only inside the radial direction of the rotating surface with respect to the magnetic sensing element, and the magnetic path changing piece is Rotation attached to the rotation center of the rotating member body Against which the bosses placed around the Thus, the surface on the rotating body side of the magnetic path changing piece was brought into contact with the rotating body Is.
[0010]
(Function)
According to the first aspect of the present invention, when the magnetic path changing piece of the rotating member is disposed only on the radially inner side of the rotating surface with respect to the magnetic sensing element, the conventional configuration of FIGS. In contrast, there is no need to increase the size of the rotating plate, and thus the rotating member is made compact.
[0012]
Thus, when the rotating member itself is made compact, the weight can be reduced, and even if the rotating member is rotated at a high speed, the air resistance of the magnetic path changing piece does not increase.
[0013]
According to the second aspect of the present invention, the magnetic path changing piece is also used as a boss arranged around the rotating shaft attached to the rotation center of the rotating member, so that the boss is provided separately. There is no need. Therefore, the weight of the rotating member can be reduced.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
(First Reference example )
Hereinafter, the present invention is embodied in a rotational position sensor. Reference example Will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the structure corresponded to the said conventional form.
[0016]
FIG. 1 is an exploded perspective view of a main part of the rotational position sensor. A rotation position sensor 100 as a rotation detection sensor is composed of a rotation plate 2 and a magnetic detection member 3 as rotation members made of iron plates.
[0017]
The rotating plate 2 is penetrated and attached to the motor shaft 4 of the motor at the boss portion 17, and rotates around the axis O as the motor shaft 4 rotates. The boss portion 17 is formed with a through hole 9 through which the motor shaft 4 is inserted and fixed. Three magnetic path changing pieces 18 a, 18 b, 18 c are provided on the outermost peripheral portion of the rotating plate 2.
[0018]
That is, as shown in FIG. 2, the magnetic path changing pieces 18 a, 18 b, and 18 c are located at a position slightly separated from the axis O with respect to the rotation surface of the rotating plate 2. Is formed so as to extend in the shape of a circular arc in section. The magnetic path changing pieces 18a, 18b, 18c are formed so that one end to the other end form an angle of 60 degrees when viewed from the axis O. Further, the interval between the magnetic path changing pieces 18a, 18b, 18c is formed so as to form an angle of 60 degrees when viewed from the axis O.
[0019]
Therefore, these magnetic path changing pieces 18a, 18b, 18c and these magnetic path changing pieces 18a, 18b, 18c are formed at an angle of 60 degrees when viewed from the axis O at the outermost peripheral portion in the plane of the rotating plate 2. The spaces 19a, 19b, and 19c that are not performed exist alternately.
[0020]
The detection unit main body 10 of the magnetic detection member 3 is disposed outside the magnetic path changing pieces 18, 18 b, 18 c formed on the rotating plate 2.
In the detection unit main body 10, three first to third magnetic detection bodies 13, 14, and 15 are sealed with a resin mold material 12, and are fixed to the distal end portion of the support arm 11. The base end portion of the support arm 11 is fixed to a fixing member (not shown). The first magnetic detection body 13 includes a first magnetoresistive element 13a as a magnetic detection element and a first bias magnet 13b as a magnet. The first bias magnet 13b is arranged so that the axis O side is N-pole and the outside is S-pole, and is on the axis O side with respect to the first magnetoresistive element 13a and in the clockwise direction in FIG. It is arranged with an offset.
[0021]
The first magnetoresistive element 13a is a magnetoresistive element whose detection voltage changes depending on the direction of the magnetic flux of the first bias magnet 13b, and has four resistance values whose resistance values change depending on the direction of the magnetic flux as shown in FIG. Resistors R1, R2, R3, and R4 are provided. The group of the two resistors R1 and R4 is arranged in the same arrangement direction, and the group of the two resistors R2 and R3 is in the arrangement direction orthogonal to the arrangement direction to which the resistors R1 and R4 are directed. Are arranged.
[0022]
Book Reference example The change range of the direction of the magnetic flux in the direction from the time when the direction of the magnetic flux becomes a predetermined angle in the counterclockwise direction with respect to the substantially radial direction from the axis O to a predetermined angle in the clockwise direction with respect to the substantially radial direction. It is up to the range when it becomes the direction.
[0023]
Each of the resistors R1 to R4 is formed by forming a Ni—CO thin film in a zigzag manner on the substrate, that is, in a polygonal line shape. The resistors R1 to R4 are set to have the same resistance value under the same temperature atmosphere. The resistors R1 to R4 have sensitivity temperature characteristics that change in sensitivity when the ambient temperature rises. In this sensitivity temperature characteristic, it is preferable that the sensitivity temperature change rate and the resistance temperature change rate coincide with each other.
[0024]
When the direction of the magnetic flux is a direction that forms a predetermined angle in the counterclockwise direction with respect to the substantially radial direction from the axis O, the resistors R1 and R4 are in the first state in which the resistance value is increased, and the resistors R2 and R3 are arranged so as to be in a second state in which the resistance value becomes small. When the direction of the magnetic flux is a direction that forms a predetermined angle in the clockwise direction with respect to the substantially radial direction, the resistors R1 and R4 are The resistors R2 and R3 are arranged so as to be in the first state in which the resistance value is increased while the resistance value is in the second state in which the resistance value is decreased. Therefore, these states occur alternately according to the change in magnetic flux.
[0025]
The resistors R1 to R4 are connected 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.
[0026]
The comparator CP and the four-terminal bridge circuit B constitute a detection circuit DC.
The resistors R1 and R4 constituting the bridge circuit B of the detection circuit DC have a potential at the midpoint a when the direction of the magnetic flux is a predetermined angle in the counterclockwise direction with respect to the substantially radial direction from the axis O. Becomes an L level smaller than the reference voltage at the middle point b.
[0027]
When the direction of the magnetic flux is a direction that forms a predetermined angle in the clockwise direction with respect to the substantially radial direction, the potential at the midpoint a is higher than the reference voltage at the midpoint b.
Book Reference example The detection point P at is the edge portion in the rotation direction of the magnetic path changing pieces 18a, 18b, 18c being moved (rotated).
[0028]
The second magnetic detection body 14 includes a second magnetoresistive element 14a as a magnetic detection 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. The second magnetoresistive element 14a and the second bias magnet 14b are respectively 40 clockwise with respect to the axis O in FIG. 2 with respect to the first magnetoresistive element 13a and the first bias magnet 13b. Arranged at the position of degrees.
[0029]
Similarly to the first magnetoresistive element 13a, the second magnetoresistive element 14a is a magnetic sensing element whose detection voltage changes depending on the direction of the magnetic flux of the second bias magnet 14b. Resistors R1 to R4 are provided and operate in the same manner as the first magnetoresistive element 13a.
[0030]
Further, the resistors R1 to R4 of the second magnetoresistive element 14a constitute a 4-terminal bridge circuit similar to the case of the first magnetoresistive element 13a. Furthermore, the resistors R1 to R4 of the second magnetoresistive element 14a together with the comparator CP constitute a detection circuit DC. The operations of the detection circuit DC and the bridge circuit B function (act) in the same manner as the detection circuit DC in the case of the first magnetoresistive element 13a.
[0031]
The third magnetic detector 15 includes a third magnetoresistive element 15a as a magnetic detection 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 respectively counterclockwise with respect to the first magnetoresistive element 13a and the first bias magnet 13b in FIG. It is disposed at a position of 40 degrees.
[0032]
Similarly to the first magnetoresistive element 13a, the third magnetoresistive element 15a is a magnetic sensing element whose detection voltage changes depending on the direction of the magnetic flux of the third bias magnet 15b. Resistors R1 to R4 are provided and operate in the same manner as the first magnetoresistive element 13a.
[0033]
The resistors R1 to R4 of the third magnetoresistive element 15a constitute a four-terminal bridge circuit as in the case of the first magnetoresistive element 13a. Further, the resistors R1 to R4 of the third magnetoresistive element 15a together with the comparator CP constitute a detection circuit DC. This detection circuit DC function (function) similarly to the detection circuit 20 in the case of the first magnetoresistive element 13a.
[0034]
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 corresponds to the position of the third bias magnet 15b shown in FIG. That is, when any one of the magnetic path changing pieces 18a to 18c is located on the radiation passing through the north pole from the axis O (hereinafter referred to as the inner side), the magnetic fluxes are approximately in the radial direction. On the other hand, the direction is a predetermined angle in the counterclockwise direction.
[0035]
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 attracted to the magnetic path changing pieces 18a to 18c from the N poles of the first to third bias magnets 13b to 15b. Because. As a result, the direction of the magnetic flux is a direction that forms 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.
[0036]
Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B is L level. Further, 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 a second bias magnet 14b shown in FIG. When the magnetic path changing pieces 18a to 18c are not located on the inner side of the N pole, these magnetic fluxes are oriented in a clockwise direction with respect to the substantially radial direction. This is because there is no magnetic path change piece 18a to 18c that forms a magnetic path, and therefore no magnetic flux is drawn. As a result, the magnetic flux extends radially, and the direction of the magnetic flux is a direction that forms a predetermined angle in the clockwise direction with respect to the substantially radial direction.
[0037]
Therefore, in this case, the voltage at the midpoint a of the four-terminal bridge circuit B is H level. Furthermore, 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 the first bias magnet 13b shown in FIG. When passing the ends of the magnetic path changing pieces 18a to 18c from the position where the magnetic path changing pieces 18a to 18c are not located, the directions of the magnetic fluxes form a predetermined angle in the clockwise direction with respect to the substantially radial direction. The direction changes from a direction to a direction that forms a predetermined angle in a counterclockwise direction with respect to the substantially radial direction.
[0038]
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 end from a certain position, the directions of the magnetic fluxes are in a counterclockwise direction with respect to the substantially substantially radial direction, so that they are clockwise with respect to the substantially radial direction. It changes to a direction that makes a predetermined angle in the surrounding direction.
[0039]
Therefore, in this case, the middle point a of the four-terminal bridge circuit B outputs a voltage that rises from L level to H level.
In this way, the potential at the midpoint a of the four-terminal bridge circuit B becomes H level and L level, and falls based on the midpoint b on the side that becomes the reference voltage (threshold voltage) by the comparator CP of the detection circuit DC. Is shaped into a detection signal that becomes steep.
[0040]
Next, features of the rotational position sensor 100 configured as described above will be described.
(1) Book Reference example Then, the detector main body 10 composed of the first to third magnetoresistive elements 13a to 15a and the first to third bias magnets 13b to 15b is arranged on the radially outer side of the rotating surface of the rotating plate 2, that is, a magnetic path. It arrange | positioned only to the outer side of the change pieces 18a-18c.
[0041]
As a result, the magnetic path changing pieces 18 a to 18 c are arranged on the inner side in the radial direction with respect to the magnetic detection member 3, and thus are located on the center side of the rotating plate 2. Accordingly, the rotating plate 2 (rotating member) itself can be made compact, and the weight can be reduced as compared with the case where the magnetic path changing pieces 18a, 18b, and 18c of the rotating plate 2 are arranged radially outside the magnetic detecting member 3. It becomes. Further, even if the rotating plate 2 is rotated at a high speed, the magnetic path changing pieces 18a, 18b, 18c than the case where the magnetic path changing pieces 18a, 18b, 18c of the rotating plate 2 are arranged radially outside the magnetic detection member 3 are used. The air resistance is not increased.
[0042]
For this reason, when the rotating plate 2 is attached to the motor shaft 4, the rotational load of the motor can be reduced and does not increase.
(2) Books Reference example Then, since the detection part main body 10 is arrange | positioned in the radial direction outer side of the rotating surface of the rotating plate 2, a rotation position sensor does not enlarge.
[0043]
(3) Books Reference example Then, since the magnetic path changing pieces 18a to 18c are formed integrally with the rotating plate 2, there is no increase in the number of parts and the assembling man-hour does not increase.
(Actual Embodiment)
Next, the present invention one The embodiment will be described with reference to FIGS.
[0044]
For convenience of explanation, the first Reference example The same reference numerals are used for members that are the same as those in FIG.
As shown in FIGS. 5 and 6, the rotational position sensor 40 has the first position. Reference example In the configuration, the magnetic path changing pieces 18a to 18c are omitted, and the magnetic path changing pieces 36a, 36b, and 36c having a fan-shaped cross section extending from the motor shaft 4 to the outermost peripheral portion are formed on the rotating plate 2. The magnetic path changing pieces 36a, 36b, 36c are formed so that one end to the other end form an angle of 60 degrees when viewed from the axis. The intervals formed by the magnetic path changing pieces 36a, 36b, 36c are formed so as to form an angle of 60 degrees when viewed from the axis.
[0045]
Accordingly, the magnetic path changing pieces 36a, 36b, 36c and the magnetic path changing pieces 36a, 36b, 36c are formed at an angle of 60 degrees when viewed from the axial center on the inner peripheral portion in the plane of the rotating plate 2. The spaces 37a, 37b, and 37c that are not present alternately exist. Further, the inner peripheral surfaces of the magnetic path changing pieces 36a, 36b, 36c are in contact with the motor shaft 4, and therefore the magnetic path changing pieces 36a, 36b, 36c also serve as the bosses of the rotating plate 22. Yes.
[0046]
The magnetic detection member 43 includes a detection unit main body 44 and the support arm 11. The detector main body 44 is disposed so as to be located outside the magnetic path changing pieces 36a, 36b, 36c formed on the rotating plate 2.
[0047]
In the detection unit main body 44, three first to third magnetic detection bodies 45, 46, and 47 are sealed with the resin mold material 12, and are fixed to the distal end portion of the support arm 11.
The first magnetic detection body 45 includes a first magnetoresistive element 45a as a magnetic detection element and a first bias magnet 45b as a magnet. The first bias magnet 45b is arranged so that the axis O side is an N pole and the outside is an S pole, and is arranged outside the first magnetoresistive element 45a and offset in the clockwise direction in FIG. Has been.
[0048]
The first magnetoresistive element 45a is a magnetoresistive element whose detection voltage changes depending on the direction of the magnetic flux of the first bias magnet 45b, and has four resistance values whose resistance values change depending on the direction of the magnetic flux as shown in FIG. Resistors R1, R2, R3, and R4 are provided. The group of two resistors R1 and R4 is arranged in the same arrangement direction, and the group of resistors R2 and R3 is arranged in an arrangement direction orthogonal to the arrangement direction in which the resistors R1 and R4 are directed.
[0049]
The change range of the direction of the magnetic flux in this embodiment is the first. Reference example Similarly, the range from when the direction of the magnetic flux is a predetermined angle in the counterclockwise direction with respect to the substantially radial direction from the axis O to the direction of the predetermined angle in the clockwise direction with respect to the substantially radial direction. Up to. The first resistor R1 to R4 are also configured and arranged in the first manner. Reference example It is provided in the same way. Each of the resistors R1 to R4 constitutes 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 the first. Reference example Similarly, a connection point (middle point) b between the resistor R3 and the resistor R4 is connected to an inverting input terminal of the comparator CP.
[0050]
In the present embodiment, the detection point P is an edge portion in the rotational direction of the magnetic path changing pieces 36a, 36b, 36c that are moving (rotating).
The second magnetic detection body 46 includes a second magnetoresistive element 46a as a magnetic detection 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 is the same as the positional relationship between the first magnetoresistive element 45a and the first bias magnet 45b. The second magnetoresistive element 46a and the second bias magnet 46b are respectively clockwise with respect to the axis O in FIG. 6 with respect to the first magnetoresistive element 45a and the first bias magnet 45b, respectively. Is disposed at a position of 40 degrees.
[0051]
Similar to the first magnetoresistive element 45a, the second magnetoresistive element 46a is a magnetoresistive element whose detection voltage changes depending on the direction of the magnetic flux of the second bias magnet 46b. Four resistors R1 to R4 whose resistance values change are provided, and are configured and arranged in the same manner as the first magnetic resistor 45a and perform the same operation.
[0052]
Further, the resistors R1 to R4 of the second magnetoresistive element 46a constitute a 4-terminal bridge circuit similar to the case of the first magnetoresistive element 45a. Furthermore, the resistors R1 to R4 of the second magnetoresistive element 46a together with the comparator CP constitute a detection circuit DC. The operations of the detection circuit DC and the bridge circuit B function (act) in the same manner as the detection circuit DC in the case of the first magnetoresistive element 45a.
[0053]
The third magnetic detector 47 includes a third magnetoresistive element 47a as a magnetic detection element and a third bias magnet 47b as a magnet. The positional relationship between the third magnetoresistive element 47a and the third bias magnet 47b is the same as the positional relationship between the first magnetoresistive element 45a and the first bias magnet 45b. The third magnetoresistive element 47a and the third bias magnet 47b are counterclockwise about the axis O in FIG. 6 with respect to the first magnetoresistive element 45a and the first bias magnet 45b, respectively. Arranged at a position of 40 degrees in the direction.
[0054]
The third air resistance element 47a is a magnetoresistive element whose detection voltage changes depending on the direction of the magnetic flux of the third bias magnet 47b, similar to the first magnetoresistance element 45a. Four resistors R1 to R4 whose resistance values change are provided, and are configured and arranged in the same manner as the first magnetic resistor 45a and perform the same operation.
[0055]
Further, the resistors R1 to R4 of the third magnetoresistive element 47a constitute a 4-terminal bridge circuit similar to the case of the first magnetoresistive element 45a. Further, the resistors R1 to R4 of the third magnetoresistive element 47a together with the comparator CP constitute a detection circuit DC. The operations of the detection circuit DC and the bridge circuit B function (act) in the same manner as the detection circuit DC in the case of the first magnetoresistive element 45a.
[0056]
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 positioned 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 positioned in front of the N pole. The magnetic flux directions of the first to third bias magnets 47b to 47b are such that the magnetic flux forms a predetermined angle in the counterclockwise direction with respect to the substantially radial direction. This is because the magnetic flux is attracted to the magnetic path changing pieces 36a to 36c from the N poles of the first to third bias magnets 45b to 47b. As a result, the direction of the magnetic flux is a direction that forms a predetermined angle in the counterclockwise direction with respect to the magnetic path changing pieces 36a to 36c, that is, the substantially radial direction.
[0057]
Therefore, in this case, the voltage at the middle point a of the four-terminal bridge circuit B is L level. Further, in the relative positional relationship between the first to third bias magnets 45b to 47b and the magnetic path changing pieces 36a to 36c, the first to third bias magnets 45b to 47b are positioned at the position of the second bias magnet 46b shown in FIG. When the magnetic path changing pieces 36a to 36c are not located in front of the N pole, the magnetic fluxes of the first to third bias magnets 45b to 47b are predetermined in the clockwise direction with respect to the radial direction. The direction is an angle. This is because there is no magnetic path changing piece 36a to 36c 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 a direction that forms a predetermined angle in the clockwise direction with respect to the substantially radial direction.
[0058]
Therefore, in this case, the voltage at the midpoint a of the four-terminal bridge circuit B is H level. Furthermore, in the relative positional relationship between the first to third bias magnets 45b to 47b and the magnetic path changing pieces 36a to 36c, each of the first to third bias magnets 45b to 47b is the first bias magnet 45b shown in FIG. When the ends of the magnetic path changing pieces 36a to 36c pass from a position where the magnetic path changing pieces 36a to 36c are not in front of the N pole, the magnetic fluxes of the first to third bias magnets 45b to 47b are passed. The direction changes from a direction that makes a predetermined angle in the clockwise direction with respect to the substantially radial direction to a direction that makes a predetermined angle in the counterclockwise direction with respect to the substantially radial direction.
[0059]
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 ends of the magnetic path changing pieces 36a to 36c pass from the position where the magnetic path changing pieces 36a to 36c are in front of the first to third magnetoresistive elements 45a to 47a, the first to third bias magnets are passed. The direction of the magnetic fluxes 45b to 47b changes from a direction that makes a predetermined angle in the counterclockwise direction with respect to the substantially radial direction to a direction that makes a predetermined angle in the clockwise direction with respect to the substantially radial direction.
[0060]
Therefore, in this case, the midpoint a of the 4-terminal bridge circuit B outputs a voltage that rises from the L level to the H level.
In this way, the potential at the midpoint a of the four-terminal bridge circuit B becomes H level and L level, and falls based on the midpoint b on the side that becomes the reference voltage (threshold voltage) by the comparator CP of the detection circuit DC. Is shaped into a detection signal that becomes steep.
[0061]
Next, the features of the rotational position sensor 40 configured as described above will be described.
(1) In this embodiment, a small-diameter rotating plate 2 is used, and magnetic path changing pieces 36 a, 36 b, 36 c extending from the motor shaft 4 to the outermost peripheral portion are formed on the rotating plate 2. A magnetic detection member 43 is disposed on the outer periphery.
[0062]
Therefore, the rotating plate 2 of the present embodiment can reduce the mass as compared with the conventional rotating plate 2. Therefore, for example, when this rotational position sensor 40 is used to detect the rotation of the motor shaft 4, it is possible to reduce the load applied to the motor and suppress the increase in current consumption.
[0063]
(No. 2 Reference examples )
Next, a rotation position sensor 200 as a rotation detection sensor Pertaining to First 2 Reference examples Will be described with reference to FIGS. Book Reference example 10 and FIG. 11 is modified, and the same components as those in the conventional device are denoted by the same reference numerals, and only different portions are omitted.
[0064]
Book Reference example Then, as shown in FIGS. 8 and 9, the magnetic path forming convex portion 8 is omitted, and the rotating plate 2 is integrally fixed to the motor shaft 4. Therefore, the book Reference example Then, when the rotary plate 2 is cut from the magnetic path changing pieces 6 a to 6 c toward the axis O, the magnetic path changing pieces 6 a to 6 c and the rotary plate 2 form an L shape.
[0065]
Ie book Reference example Then, the rotating plate 2 in which a plurality of magnetic path changing pieces 6a to 6c are erected at predetermined intervals around the rotation center of the rotating surface, and the bias magnet 13b disposed in a predetermined direction with respect to the rotating plate 2. To 15b and magnetoresistive elements 13a to 15a for detecting the same bias magnets 13b to 15b. And magnetic path change piece 6a-6c was arrange | positioned only on the outer side of the radial direction of the rotating surface with respect to the magnetoresistive elements 13a-15a.
[0066]
As a result, the book Reference example Then, the rotation plate 2 can be reduced in diameter by the amount that the magnetic path forming convex portion 8 is omitted, and as a result, the size and weight can be reduced.
Embodiment And reference examples Is the above Embodiments and reference examples However, the present invention is not limited to the above and may be changed as follows.
[0067]
○ The embodiment And reference examples Then, the magnetic path changing pieces 18a to 18c and 36a to 36c are formed so that one end to the other end form an angle of 60 degrees when viewed from the axis O, that is, at intervals of 60 degrees, and the magnetic detectors 13, 14, As viewed from the axis O, 15 was set at an interval of 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. In this way, each embodiment And reference examples A finer angle can be detected.
[0068]
【The invention's effect】
As detailed above, the claims 1 According to the invention described in (2), the rotating member can be reduced in weight, and the load on the rotating body can be reduced.
[0069]
According to the invention described in claim 2, since the magnetic path changing piece is also used as a boss arranged around the rotating shaft attached to the rotation center of the rotating member, it is necessary to provide a boss separately. Therefore, it is possible to reduce the weight of the rotating member.
[Brief description of the drawings]
FIG. 1 Reference example The principal part disassembled perspective view of this rotational position sensor.
FIG. 2 is a plan view showing the positional relationship between the rotating plate and the magnetic detection member.
FIG. 3 is a cross-sectional view of the main part of the rotational position sensor.
FIG. 4 is an equivalent circuit diagram of a magnetoresistive element.
[Figure 5] Fruit The principal part disassembled perspective view of the rotation position sensor for demonstrating embodiment.
FIG. 6 is a plan view showing the positional relationship between the rotating plate and the magnetic detection member.
FIG. 7 is a cross-sectional view of the main part of the rotational position sensor.
FIG. 8 2 Reference examples The principal part disassembled perspective view of the rotation position sensor for demonstrating.
FIG. 9 is a plan view showing the positional relationship between the rotating plate and the magnetic detection member.
FIG. 10 is an exploded perspective view of a main part of a conventional rotational position sensor proposed by the applicant.
FIG. 11 is a plan view showing the positional relationship between the rotary plate and the magnetic detection member.
[Explanation of symbols]
40, 100, 200 ... rotation position sensor as rotation detection sensor, 2 ... rotation plate
3 ... magnetic detection member, 4 ... motor shaft as rotating body,
6a-6c, 18a-18c, 36a-36c ... Magnetic path changing piece,
19a to 19c ... space, 9 ... through hole, 10 ... detector 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 ... 1st magnetoresistive element,
13b, 45b ... 1st bias magnet,
14a, 46a ... 2nd magnetoresistive element,
14b, 46b ... second bias magnet,
15a, 47a ... 3rd magnetoresistive element,
15b, 47b ... third bias magnet,
Vout: detection voltage, R1 to R4: resistor.

Claims (2)

The rotating member (2), the rotating body (4) attached to the rotating center of the rotating member (2), and the rotating member at a predetermined interval around the rotating center of the rotating surface of the rotating member (2). A plurality of magnetic path changing pieces (36a to 36c) erected in the axial direction of the body (4) and magnets (45b to 47b) arranged in a predetermined direction with respect to the rotating member (2) And a rotation detection sensor comprising magnetic detection elements (45a to 47a) for detecting magnetic flux of the magnets (45b to 47b),
The magnetic path changing pieces (36a to 36c) are disposed only on the inner side in the radial direction of the rotation surface with respect to the magnetic sensing elements (45a to 47a), and the magnetic path changing pieces (36a to 36c) are arranged. A rotation detection sensor having a surface on the rotating body (4) side in contact with the rotating body (4). A rotating member (2) in which a plurality of magnetic path changing pieces (36a to 36c) are erected at predetermined intervals around the rotation center of the rotating surface, and disposed in a predetermined direction with respect to the rotating member (2). It has been a magnet (45b~47b), in the rotation detecting sensor consisting of a magnetic sensing element (45a~47a) for detecting a magnet (45b~47b),
The magnetic path changing pieces (36a to 36c) are arranged only on the inner side in the radial direction of the rotation surface with respect to the magnetic sensing elements (45a to 47a), and the magnetic path changing pieces (36a to 36c) are rotated. the rotating body of the member I der which also serves as a boss which is disposed around respect attached to the rotating body to the rotational center of (2) (4), the magnetic path changing pieces (36 a - 36 c) ( 4) A rotation detection sensor in which the surface on the side is in contact with the rotating body (4) .

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