JP2019109053A - Rotation angle detector - Google Patents

Abstract

To provide a rotation angle detector capable of suppressing an increase in weight and improving detection accuracy.SOLUTION: When an angle half of the angle between a center O of a rotor 1 and both ends of a bias magnetic field generator 21 in the circumferential direction is defined as (a), an angle between the center O of the rotor 1 and both ends of the gap between the bias magnetic field generator 21 and a magnetic material circumferential direction outer portion 242 in the circumferential direction is defined as (b), and an angle between the center O of the rotor 1 and both ends of the magnetic material circumferential direction outer portion 242 in the circumferential direction is defined as (c), a+b>180/X and a+b+c<360/X are satisfied.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rotation angle detection device using a change in magnetic field strength.

  Conventionally, there has been known a rotation angle detection device including a rotor having an uneven portion made of a magnetic material on an outer peripheral surface, and a stator provided opposite to the uneven portion. The stator has a plurality of magnetic flux density detection units arranged in the circumferential direction of the rotor. In addition, the stator is provided outside the respective magnetic flux density detection portions in the radial direction, and has magnets formed so as to be superimposed on the respective magnetic flux density detection portions in the radial direction and extend in the circumferential direction. In addition, the stator has a pair of magnetic members that sandwich a magnet in the circumferential direction (see, for example, Patent Document 1).

Japanese Utility Model Application Publication No. 4-94581

  However, when the dimension of the magnetic member in the circumferential direction of the rotor is small, the leakage flux which does not pass through the magnetic member increases. Thereby, the variation in the amplitude of the magnetic flux density detected in each of the plurality of magnetic flux density detection units becomes large. As a result, the detection accuracy of the rotation angle detection device is lowered. When the dimension of the magnetic member in the circumferential direction of the rotor is increased, there is a problem that the weight of the rotation angle detection device increases.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a rotation angle detection device capable of suppressing an increase in weight and improving detection accuracy.

  The rotation angle detection device according to the present invention includes a rotor having a concavo-convex portion formed of a magnetic material on an outer peripheral surface, and a fixing provided opposite to the concavo-convex portion and having a bias magnetic field generation portion and a plurality of magnetic flux density detection portions. A magnetic body having a magnetic material radial direction outer portion provided outside the bias magnetic field generating portion in the radial direction of the rotor and a pair of magnetic body circumferential outer portions sandwiching the bias magnetic field generating portion in the circumferential direction of the rotor And the concavo-convex portion is formed to change by an X cycle with respect to a mechanical angle of 360 degrees in the circumferential direction when X is an integer of 1 or more, and the plurality of magnetic flux density detection portions The magnetic flux density detection portion is provided on the outer side of the respective magnetic flux density detection portions in the radial direction. , In the radial direction The magnetic flux density detection portion is overlapped with and formed in the circumferential direction, and the magnetic material circumferential direction outer side portion is provided radially inward of the bias magnetic field generation portion, and both ends of the bias magnetic field generation portion in the circumferential direction A half angle of the angle between the part and the center of the rotor is a, and between the both ends of the gap between the bias magnetic field generating part and the magnetic material circumferential direction outer part in the circumferential direction and the center of the rotor Assuming that the angle is b and the angle between the both ends of the outer circumferential portion of the magnetic material in the circumferential direction and the center of the rotor is c, a + b> 180 / X and a + b + c <360 / X are satisfied.

  According to the rotation angle detection device according to the present invention, it is possible to suppress an increase in the size of the outer peripheral portion of the magnetic body in the circumferential direction of the rotor and to suppress the amplitude of the magnetic flux density detected in each of the plurality of magnetic flux density detectors. Variations can be reduced. Thus, it is possible to suppress an increase in the weight of the rotation angle detection device and to improve the detection accuracy of the rotation angle detection device.

It is a plane sectional view showing the rotation angle detecting device concerning Embodiment 1 of this invention. It is an enlarged view which shows the A section of the rotation angle detection apparatus of FIG. It is a block diagram which shows the stator of FIG. It is a plane sectional view which shows the principal part of the rotation angle detection apparatus which concerns on Embodiment 2 of this invention. It is a plane sectional view which shows the principal part of the rotation angle detection apparatus which concerns on Embodiment 3 of this invention. It is a plane sectional view showing an important section of a rotation angle detecting device in the case of alpha> beta and gamma> 0. It is a graph which shows the magnetic flux density which three magnetic flux density detection parts of FIG. 6 detect. It is a table | surface which shows the ratio of the amplitude of the magnetic flux density which three magnetic flux density detection parts of FIG. 6 detect. It is a plane sectional view showing an important section of a rotation angle detecting device in the case of alpha <beta, gamma <0. It is a graph which shows the magnetic flux density which three magnetic flux density detection parts of FIG. 9 detect. It is a table | surface which shows the ratio of the amplitude of the magnetic flux density which three magnetic flux density detection parts of FIG. 9 detect. It is a plane sectional view showing an important section of a rotation angle detecting device in the case of alpha = beta. It is a graph which shows the magnetic flux density which three magnetic flux density detection parts of FIG. 12 detect. It is a table | surface which shows the ratio of the amplitude of the magnetic flux density which three magnetic flux density detection parts of FIG. 12 detect. It is a plane sectional view which shows the principal part of the rotation angle detection apparatus which concerns on Embodiment 4 of this invention. It is an enlarged view which shows the B section of FIG. It is a plane sectional view which shows the principal part of the rotation angle detection apparatus which concerns on Embodiment 5 of this invention. It is an enlarged view which shows the C section of FIG. It is an enlarged view which shows the D section of FIG. It is a plane sectional view which shows the principal part of the rotation angle detection apparatus which concerns on Embodiment 6 of this invention.

Embodiment 1
FIG. 1 is a plan sectional view showing a rotation angle detection device according to a first embodiment of the present invention, and FIG. 2 is an enlarged view showing a portion A of the rotation angle detection device of FIG. The rotation angle detection device according to the first embodiment includes a rotor 1 and a stator 2 provided outside the rotor 1 in the radial direction of the rotor 1 and extending in the circumferential direction of the rotor 1. Hereinafter, the radial direction refers to the radial direction of the rotor 1, the circumferential direction to the circumferential direction of the rotor 1, and the axial direction to the axial direction of the rotor 1.

  The rotor 1 has a cylindrical rotary shaft 11 and a concavo-convex portion 12 provided on the outer side of the rotary shaft 11 in the radial direction. The uneven portion 12 is disposed on the outer peripheral surface of the rotor 1. The uneven portion 12 is made of a magnetic material. The uneven portion 12 is formed to change by an X cycle with respect to a mechanical angle of 360 degrees in the circumferential direction when X is an integer of 1 or more. FIG. 1 shows the uneven portion 12 in the case of X = 12.

  The stator 2 is provided to face the uneven portion 12 in the radial direction. The stator 2 has one bias magnetic field generation unit 21 and a plurality of magnetic flux density detection units 22. The bias magnetic field generation unit 21 is provided outside the respective magnetic flux density detection units 22 in the radial direction. In addition, the bias magnetic field generation unit 21 is formed so as to overlap the respective magnetic flux density detection units 22 in the radial direction and extend in the circumferential direction. The plurality of magnetic flux density detection units 22 are disposed to face the uneven portion 12 with a gap therebetween. The plurality of magnetic flux density detection units 22 are provided at regular intervals along the circumferential direction during one cycle of the uneven portion 12. FIG. 2 shows the stator 2 in the case where the number of the magnetic flux density detection units 22 is three.

  FIG. 3 is a block diagram showing the stator 2 of FIG. The stator 2 further includes a rotation angle calculation processing unit 23 that calculates the rotation angle of the rotor 1 using each of the plurality of detection signals obtained by the plurality of magnetic flux density detection units 22.

  As shown in FIGS. 1 and 2, the stator 2 further includes a magnetic member 24. The magnetic member 24 is made of a magnetic material. The magnetic member 24 has a magnetic material radial direction outer portion 241 provided on the outer side of the bias magnetic field generating portion 21 in the radial direction. The magnetic material radial direction outer side portion 241 is disposed so as to overlap the bias magnetic field generating portion 21 in the radial direction. The magnetic material radial direction outer side portion 241 is disposed to extend in the circumferential direction. The magnetic material radial direction outer portion 241 is formed so that the dimension in the radial direction is constant over the entire circumferential direction. Both circumferential end portions of the magnetic material radial direction outer side portion 241 protrude outward in the circumferential direction more than circumferential end portions of the bias magnetic field generating portion 21.

  In addition, the magnetic member 24 has a pair of magnetic outer circumferential portions 242 sandwiching the bias magnetic field generating portion 21 in the circumferential direction. The inner end portion of the magnetic body circumferential direction outer side portion 242 in the radial direction is provided on the inner side in the radial direction from the inner end portion of the bias magnetic field generating portion 21 in the radial direction. The pair of magnetic body circumferential direction outer side portions 242 is connected to both end portions of the magnetic body radial direction outer side portion 241 in the circumferential direction.

  The outer surface of the magnetic material radial direction outer portion 241 in the radial direction and the outer surface of the magnetic material circumferential direction outer portion 242 in the radial direction are the centers of the rotor 1 when viewed in the axial direction of the rotor 1 It is arranged on the same circle centering on O.

  An angle half of the angle between the both ends of the bias magnetic field generating unit 21 and the center O of the rotor 1 in the circumferential direction is a. An angle between the both ends of the gap between the bias magnetic field generating unit 21 and the magnetic material circumferential direction outer portion 242 in the circumferential direction and the center O of the rotor 1 is b. An angle between both ends of the magnetic material circumferential direction outer side portion 242 in the circumferential direction and the center O of the rotor 1 is c. In this case, the stator 2 is formed to satisfy a + b> 180 / X and a + b + c <360 / X.

  In order to improve the detection accuracy of the rotation angle detection device, it is necessary to equalize the amplitudes of the magnetic flux density detected by each of the three magnetic flux density detection units 22. In order to satisfy this condition, in the conventional rotation angle detection device, the magnetic material circumferential direction outer side portion is positioned 180 degrees / X outside in the circumferential direction from the magnetic flux density detection unit 22 disposed on the center side in the circumferential direction. It had to be placed across from at least 360 degrees / X to the outside position.

  In the rotation angle detection device according to the first embodiment, the position of the magnetic material protrusion outer end 243 which is the outer end portion of the magnetic material circumferential direction outer side portion 242 in the circumferential direction is the magnetic flux disposed on the center side in the circumferential direction. The position from the density detection unit 22 in the circumferential direction is 360 degrees / X outside the position in the circumferential direction. Further, in the rotation angle detection device according to the first embodiment, the position of the inner end 244 of the magnetic material protrusion, which is the inner end of the magnetic material circumferential direction outer side portion 242 in the circumferential direction, is located on the center side in the circumferential direction. The magnetic flux density detection unit 22 is located on the outer side in the circumferential direction than the position located 180 ° / X in the circumferential direction. Therefore, the increase in the dimension of the magnetic material circumferential direction outer side portion 242 in the circumferential direction is suppressed. As a result, the increase in weight of the rotation angle detection device is suppressed.

  As the position of the magnetic material protrusion outer end 243 approaches the circumferential center of the magnetic member 24, the magnetic flux density detection units 22 disposed at the circumferential center of the three magnetic flux density detection units 22 detect The amplitude of the magnetic flux density is reduced. On the other hand, as the position of the magnetic material protrusion inner end 244 moves away from the circumferential center of the magnetic material member 24, the magnetic flux density detection units disposed on the magnetic material circumferential direction outer side 242 of the three magnetic flux density detection units 22. The amplitude of the magnetic flux density detected by 22 decreases. Thereby, the variation in the amplitude of the magnetic flux density detected by each of the three magnetic flux density detectors 22 is reduced. As a result, the detection accuracy of the rotation angle detection device is improved.

  As described above, according to the rotation angle detection device according to the first embodiment of the present invention, a + b> 180 / X and a + b + c <360 / X are satisfied. Accordingly, it is possible to suppress an increase in the size of the magnetic material circumferential direction outer side portion 242 in the circumferential direction and to reduce variation in the amplitude of the magnetic flux density detected in each of the plurality of magnetic flux density detectors 22. Thus, it is possible to suppress an increase in the weight of the rotation angle detection device and to improve the detection accuracy of the rotation angle detection device.

Second Embodiment
FIG. 4 is a plan sectional view showing an essential part of a rotation angle detecting device according to Embodiment 2 of the present invention. In the rotation angle detection device according to the second embodiment, α = a + b−180 / X and β = 360 / X− (a + b + c). In this case, the stator 2 is formed to satisfy α = β. The other configuration is the same as that of the first embodiment.

  Here, α represents the angle between the inner end 244a of the magnetic body protrusion and the inner end 244 of the magnetic body protrusion in the second embodiment and the center O of the rotor 1 in an ideal magnetic body member not to be miniaturized. . β indicates the angle between the magnetic material protrusion outer end 243 a and the magnetic material protrusion outer end 243 in Embodiment 2 and the center O of the rotor 1 in an ideal magnetic material member when not miniaturized. The ideal magnetic member in the case where the size is not reduced means that the position of the inner end 244a of the magnetic material projection is outside by 180 degrees / X in the circumferential direction from the magnetic flux density detection unit 22 disposed on the center side in the circumferential direction. The magnetic member is Further, an ideal magnetic member in the case where the size is not reduced means that the position of the magnetic material protrusion outer end 243a is only 360 degrees / X in the circumferential direction from the magnetic flux density detection unit 22 disposed on the center side in the circumferential direction. It is a magnetic body member which becomes an outside position.

  Here, an ideal magnetic member in the case where it is not miniaturized is described in detail. The magnetic flux generated by the bias magnetic field generation unit 21 is the magnetic material radial direction outer part 241, the magnetic material circumferential direction outer part 242, the gap between the magnetic material circumferential direction outer part 242 and the rotor 1, the rotor 1, the bias magnetic field It passes through in order of the gap of generating part 21 and rotor 1. The amount of change in magnetoresistance of the magnetic member 24 caused by the rotation of the rotor 1 can be determined by changing the amount of change in magnetoresistance of the gap between the outer peripheral portion 242 of the magnetic body and the rotor 1 and the bias magnetic field Much smaller than the amount of magnetoresistance change in the gap. Therefore, the amount of change in magnetic resistance of the magnetic flux density detection unit 22 is determined by the amount of change in the gap between the magnetic material circumferential direction outer portion 242 and the rotor 1 and the change in the gap between the bias magnetic field generation unit 21 and the rotor 1 It is prescribed by quantity.

  In an ideal magnetic member not to be miniaturized, the position of the inner end 244a of the magnetic material projection is 180 / X degrees, and the position of the outer end 243a of the magnetic material projection is 360 / X degrees. Thus, regardless of the rotational angle of the rotor 1, the convex portion of the rotor 1 always faces the magnetic material circumferential direction outer side portion 242. Therefore, there is always a place where the gap length between the magnetic material circumferential direction outer side portion 242 and the rotor 1 is minimized. Thereby, the magnetic resistance of the gap between the magnetic material circumferential direction outer side portion 242 and the rotor 1 becomes constant regardless of the rotation angle of the rotor 1.

  The magnetic flux density detection unit 22 disposed on the center side in the circumferential direction of the three magnetic flux density detection units 22 is referred to as a central magnetic flux density detection unit. The magnetic flux density detection units 22 disposed on the side of the magnetic material circumferential direction outer portion 242 in the three magnetic flux density detection units 22 are referred to as a circumferential direction outer magnetic flux density detection unit. The maximum value of the gap length between the rotor 1 and the portion of the bias magnetic field generation unit 21 in which the central magnetic flux density detection unit 22a is disposed during one rotation of the rotor 1 corresponds to the circumferential outer magnetic flux density detection unit Between the portion of the bias magnetic field generating unit 21 in which the V.V. For the gap length between the rotor 1 and the portion of the bias magnetic field generation unit 21 in which the central magnetic flux density detection unit is arranged, the circumferential outer magnetic flux density detection unit The gap length between the portion of the arranged bias magnetic field generating portion 21 and the rotor 1 is equal to the minimum value during one rotation of the rotor 1. Therefore, the amount of change in magnetic resistance of the center-side magnetic flux density detection unit is equal to the amount of change in magnetic resistance of the circumferential outer magnetic flux density detection unit.

  The amount of change in the gap length between each of the portions of the bias magnetic field generation unit 21 in which each of the three magnetic flux density detection units 22 is disposed and the rotor 1 is equal to each other. Therefore, the amounts of change in magnetoresistance of the three magnetic flux density detectors 22 are equal to one another. The amplitude of the magnetic flux density detected by the magnetic flux density detection unit 22 is calculated by the product of the magnetomotive force of the bias magnetic field generation unit 21 and the amount of change in magnetic resistance of the magnetic flux density detection unit 22. Therefore, the amplitudes of the magnetic flux density detected by the three magnetic flux density detectors 22 are equal to one another. Thereby, the variation in the amplitude of the magnetic flux density detected by each of the three magnetic flux density detection units 22 is eliminated. As a result, the detection accuracy of the rotation angle detection device is improved.

  On the other hand, when the position of the magnetic material protrusion outer end 243 is larger than 360 degrees / X, the gap between the rotor 1 and the portion of the bias magnetic field generation unit 21 in which the center side magnetic flux density detection unit is arranged. When the length is minimized, the surface of the convex portion of the rotor 1 facing the magnetic material circumferential direction outer portion 242 is increased. As a result, the maximum value of the magnetic resistance of the central magnetic flux density detection unit is reduced. As a result, the amplitude of the magnetic flux density detected by the central magnetic flux density detection unit is increased.

  In the case where the position of the magnetic material protrusion outer end 243 is 360 degrees / X, the gap length between the rotor 1 and the portion of the bias magnetic field generating unit 21 where the circumferential outer magnetic flux density detection unit is disposed is maximum Alternatively, in the case of the minimum, the convex portion of the rotor 1 faces the magnetic material circumferential direction outer side portion 242. On the other hand, when the position of the magnetic material protrusion outer end 243 is larger than 360 degrees / X, between the rotor 1 and the portion of the bias magnetic field generation unit 21 in which the circumferential outer magnetic flux density detection unit is arranged. When the gap length is maximum or minimum, the convex portion of the rotor 1 faces the magnetic material circumferential direction outer portion 242. Therefore, even when the position of the magnetic material protrusion outer end 243 is made larger than 360 degrees / X to 360 degrees / X, the surface of the convex portion of the rotor 1 facing the magnetic material circumferential direction outer portion 242 is It does not increase. Since the magnetic material circumferential direction outer side portion 242 opposed to the concavo-convex portion 12 of the rotor 1 increases, each of the maximum value and the minimum value of the magnetic resistance of the circumferential direction outer magnetic flux density detection portion during one rotation of the rotor 1 Will decrease slightly. Therefore, the increase in the magnetic flux density detected by the circumferential outer magnetic flux density detection unit is small.

  From the above, when the position of the magnetic material protrusion outer end 243 is larger than 360 degrees / X, the amplitude of the magnetic flux density detected by the central magnetic flux density detection unit is detected by the circumferential outer magnetic flux density detection unit It becomes larger than the amplitude of the magnetic flux density. Thereby, the amplitude of the magnetic flux density which each of three magnetic flux density detection parts 22 detects differs. As a result, the detection accuracy of the rotation angle detection device is degraded.

  When the position of the magnetic material protrusion inner end 244 is smaller than 180 degrees / X, the maximum value of the magnetic resistance of the circumferential outer magnetic flux density detection unit decreases. Therefore, the amplitude of the magnetic flux density detected by the circumferential direction outer magnetic flux density detection unit is increased. On the other hand, the decrease in the maximum value and the decrease in the minimum value of the reluctance of the central magnetic flux density detection unit are minute. Thus, the increase in the amplitude of the magnetic flux density detected by the central magnetic flux density detection unit is small. Therefore, the amplitude of the magnetic flux density detected by the circumferential direction outer magnetic flux density detection unit is larger than the amplitude of the magnetic flux density detected by the center side magnetic flux density detection unit. Thereby, the amplitude of the magnetic flux density which each of three magnetic flux density detection parts 22 detects differs. As a result, the detection accuracy of the rotation angle detection device is degraded. Therefore, when the position of the magnetic material protrusion inner end 244a is 180 / X degrees and the position of the magnetic material protrusion outer end 243a is 360 / X degrees, it becomes an ideal magnetic material member in the case where the size is not reduced. .

  In the rotation angle detection device according to the second embodiment, movement inward in the circumferential direction from the position of the magnetic material protrusion outer end 243a to the position of the magnetic material protrusion outer end 243 in an ideal magnetic material member without downsizing The angle of movement is equal to the angle of circumferential outward movement from the position of the magnetic material protrusion inner end 244a in the ideal magnetic material member in the case where miniaturization is not performed to the position of the magnetic material protrusion inner end 244. Thereby, the decrease value of the amplitude of the magnetic flux density detected by the magnetic flux density detection unit 22 disposed on the magnetic material circumferential direction outer side 242 side in the three magnetic flux density detection units 22 and the three magnetic flux density detection units 22 The reduction value of the amplitude of the magnetic flux density detected by the magnetic flux density detection unit 22 disposed on the center side in the circumferential direction becomes equal.

  As described above, according to the rotation angle detection device according to the second embodiment of the present invention, when α = a + b−180 / X and β = 360 / X− (a + b + c), α = β is satisfied. . Thereby, the dispersion | variation in the amplitude of the magnetic flux density which each of the three magnetic flux density detection parts 22 detects can be reduced. As a result, the detection accuracy of the rotation angle detection device can be improved, and the size and weight of the rotation angle detection device can be reduced.

Third Embodiment
FIG. 5 is a plan sectional view showing an essential part of a rotation angle detecting device according to a third embodiment of the present invention. In the rotation angle detection device according to the third embodiment, α = a + b−180 / X, β = 360 / X− (a + b + c), and γ = a−180 / X. In this case, the stator 2 is formed to satisfy α> β and γ> 0, or α <β and γ <0. The other configuration is the same as that of the first embodiment.

  Here, α represents the angle between the inner end 244a of the magnetic body protrusion and the inner end 244 of the magnetic body protrusion in the third embodiment and the center O of the rotor 1 in the ideal magnetic body member when not miniaturized . β indicates the angle between the magnetic material protrusion outer end 243 a and the magnetic material protrusion outer end 243 in the third embodiment and the center O of the rotor 1 in an ideal magnetic material member when not miniaturized. The ideal magnetic member in the case where the size is not reduced means that the position of the inner end 244a of the magnetic material projection is outside by 180 degrees / X in the circumferential direction from the magnetic flux density detection unit 22 disposed on the center side in the circumferential direction. The magnetic member is Further, an ideal magnetic member in the case where the size is not reduced means that the position of the magnetic material protrusion outer end 243a is only 360 degrees / X in the circumferential direction from the magnetic flux density detection unit 22 disposed on the center side in the circumferential direction. It is a magnetic body member which becomes an outside position.

  The angle of circumferential inward movement from the position of the magnetic material protrusion outer end 243a to the position of the magnetic material protrusion outer end 243 in an ideal magnetic material member when not miniaturized is ideal in the case where the miniaturization is not performed This angle is smaller than the angle of the movement in the circumferential direction outward from the position of the inner end 244 a of the magnetic material protrusion in the magnetic member to the position of the inner end 244 of the magnetic material protrusion. Further, the dimension in the circumferential direction of the bias magnetic field generation unit 21 is larger than the dimension in the circumferential direction of the ideal bias magnetic field generation unit when the size is not reduced. As a result, the decrease in the amplitude of the magnetic flux density detected by the magnetic flux density detection unit 22 disposed on the side of the magnetic material circumferential direction outer portion 242 in the three magnetic flux density detection units 22 is caused by the enlargement of the bias magnetic field generation unit 21. Be compensated.

  6 is a plan sectional view showing the main part of the rotation angle detection device in the case of α> β and γ> 0, and FIG. 7 is a graph showing the magnetic flux density detected by the three magnetic flux density detectors of FIG. FIG. 8 is a table showing the ratio of the amplitudes of the magnetic flux density detected by the three magnetic flux density detectors in FIG. In FIG. 6, α = 7 degrees, β = 6 degrees, and γ = 1 degrees. 6 to 8, one of the pair of circumferential outer magnetic flux density detectors is U, the central magnetic flux density detector is V, and the other circumferential outer magnetic flux density detector is W. FIG. 8 shows the ratio of the amplitude of the magnetic flux density detected by each magnetic flux density detection unit to the amplitude of the magnetic flux density detected by the circumferential outer magnetic flux density detection unit U. As shown in FIG. 8, the amplitudes of the magnetic flux densities detected by the respective magnetic flux density detection units 22 are equal to one another.

  9 is a plan sectional view showing the main part of the rotation angle detection device in the case of α <β and γ <0, and FIG. 10 is a graph showing the magnetic flux density detected by the three magnetic flux density detectors of FIG. FIG. 11 is a table showing the ratio of the amplitudes of the magnetic flux density detected by the three magnetic flux density detectors in FIG. In FIG. 9, α = 0 degrees, β = 1 degrees, and γ = −1 degrees. 9 to 11, one of the pair of circumferential outer magnetic flux density detectors is U, the central magnetic flux density detector is V, and the other circumferential outer magnetic flux density detector is W. FIG. 11 shows the ratio of the amplitude of the magnetic flux density detected by each magnetic flux density detection unit to the amplitude of the magnetic flux density detected by the circumferential direction outer magnetic flux density detection unit U. As shown in FIG. 11, the amplitudes of the magnetic flux densities detected by the respective magnetic flux density detectors 22 are equal to one another.

  FIG. 12 is a plan sectional view showing the main part of the rotation angle detector when α = β, FIG. 13 is a graph showing the magnetic flux density detected by the three magnetic flux density detectors of FIG. It is a table | surface which shows the ratio of the amplitude of the magnetic flux density which three magnetic flux density detection parts of FIG. 12 detect. In FIG. 12, α = 3 degrees and β = 3 degrees. In FIG. 12 to FIG. 14, one of the pair of circumferential outer magnetic flux density detectors is U, the central magnetic flux density detector is V, and the other circumferential outer magnetic flux density detector is W. FIG. 14 shows the ratio of the amplitude of the magnetic flux density detected by each magnetic flux density detection unit to the amplitude of the magnetic flux density detected by the circumferential outer magnetic flux density detection unit U. As shown in FIG. 14, the amplitudes of the magnetic flux densities detected by the respective magnetic flux density detection units 22 are equal to one another.

  As described above, according to the rotation angle detection device according to the third embodiment of the present invention, α = a + b−180 / X, β = 360 / X− (a + b + c), and γ = a−180 / X. In some cases, α> β and γ> 0, or α <β and γ <0. Thereby, the dispersion | variation in the amplitude of the magnetic flux density which each of the three magnetic flux density detection parts 22 detects can be reduced. As a result, the detection accuracy of the rotation angle detection device can be improved, and the size and weight of the rotation angle detection device can be reduced.

  Further, the ideal in the case where the angle of moving inward in the circumferential direction from the position of the magnetic material protrusion outer end 243a to the position of the magnetic material protrusion outer end 243 in the ideal magnetic material member in the case of not downsizing is not miniaturization The angle may be smaller than the angle of the movement in the circumferential direction outward from the position of the inner end 244a of the magnetic member in the magnetic member to the position of the inner end 244 of the magnetic member. Thereby, the design freedom of the magnetic member 24 can be improved.

Fourth Embodiment
FIG. 15 is a plan sectional view showing an essential part of a rotation angle detecting device according to Embodiment 4 of the present invention, and FIG. 16 is an enlarged view showing a portion B of FIG. The magnetic body circumferential direction outer side portion 242 has a circumferential direction extending surface 245 extending outward in the circumferential direction from the outer side surface in the radial direction of the magnetic body radial direction outer side portion 241. In addition, the magnetic body circumferential direction outer side portion 242 has a circumferential direction outer facing surface 246 which faces the outer side in the circumferential direction. In addition, the magnetic body circumferential direction outer portion 242 has a circumferential slope 247 connected to a portion in the circumferential direction in the circumferential extension surface 245 and a portion in the circumferential direction outward in the circumferential outer facing surface 246. ing. The magnetic body circumferential direction outer side portion 242 according to the fourth embodiment is smaller in size and smaller than the magnetic body circumferential direction outer side portion 242 according to the first embodiment because the magnetic body circumferential direction outer side portion 242 has the circumferential direction slope 247. Weight reduction is achieved.

  The dimension in the radial direction at the outer end of the magnetic material radial direction outer portion 241 in the circumferential direction is d. The dimension of the circumferential extension surface 245 in the circumferential direction is e. Let the dimension of the circumferential direction outward surface 246 about radial direction be f. In this case, the magnetic member 24 is formed to satisfy d ≦ e and f ≦ d.

  The magnetic member 24 is composed of a plurality of stacked steel plates. The stator 2 has a pair of first crimps 25 provided on the respective magnetic material circumferential direction outer side portions 242. The first crimp 25 fixes each of the plurality of steel plates. The stator 2 also has a second crimp 26 provided at the center of the magnetic material radial direction outer portion 241 in the circumferential direction. The second crimp 26 fixes each of the plurality of steel plates. The other configuration is the same as that of the first embodiment, the second embodiment, or the third embodiment.

  The magnetic flux density at the end of the magnetic material radial direction outer side portion 241 on the side of the magnetic material circumferential direction outer side portion 242 is the same as the magnetic flux density at the end portion on the magnetic material radial outer side portion 241 side of the magnetic material circumferential direction outer side portion 242 It becomes the case of d = e. Considering the position of the first crimp 25 provided at the magnetic outer circumferential portion 242, the magnetic flux density at the end of the magnetic outer radial portion 241 on the magnetic outer circumferential portion 242 side, and the magnetic outer circumferential end The magnetic flux density at the end on the side of the magnetic material radial direction outer portion 241 in the portion 242 is approximately the same as in the case of d ≦ e.

  The magnetic flux passing through the magnetic material circumferential direction outer portion 242 passes through the uneven portion 12 across the gap between the magnetic material circumferential direction outer side portion 242 and the uneven portion 12 before reaching the circumferential direction outward facing surface 246. Therefore, f ≦ d may be sufficient.

  As described above, according to the rotation angle detection device of the fourth embodiment of the present invention, d ≦ e and f ≦ d are satisfied. Thereby, weight reduction and cost reduction of a rotation angle detection apparatus can be achieved. Further, by reducing the weight of the rotation angle detection device, the durability of the rotation angle detection device against vibration can be improved. In addition, by making the magnetic member 24 smaller, it is possible to reduce the influence of noise from an external device such as a motor on the detection signal of the rotation angle detection device. In addition, weight reduction of the magnetic member 24 can be achieved without reducing the magnetic flux density passing through the magnetic member 24. Thus, the weight reduction of the magnetic member 24 can be achieved without reducing the detection signal of the magnetic flux density detection unit 22. In addition, by reducing the size of the magnetic member 24, heat transfer from an external device such as a motor can be reduced. Thereby, the temperature rise of the bias magnetic field generation unit 21 can be suppressed. As a result, the demagnetization of the bias magnetic field generation unit 21 can be suppressed. When demagnetization of the bias magnetic field generation unit 21 occurs, the detection signal of the magnetic flux density detection unit 22 decreases. Therefore, by suppressing the demagnetization of the bias magnetic field generation unit 21, the detection accuracy of the rotation angle detection device can be improved.

Embodiment 5
17 is a plan sectional view showing an essential part of a rotation angle detecting device according to a fifth embodiment of the present invention, FIG. 18 is an enlarged view showing a part C of FIG. 17 and FIG. 19 is a part D of FIG. It is an enlarged view which shows. The magnetic body radial direction outer side portion 241 includes a magnetic body narrow portion 248 and a magnetic body wide portion 249 provided outside the magnetic body narrow portion 248 in the circumferential direction. The magnetic body narrowing portion 248 is provided in a portion between the central portion and the outer end portion in the circumferential direction in the magnetic body radial direction outer side portion 241. A circumferentially extending recess 250 is formed on the outer surface of the magnetic substance narrowing portion 248 in the radial direction. The dimension of the magnetic body wide portion 249 in the radial direction is larger than the dimension of the magnetic body narrow portion 248 in the radial direction.

  The dimension of the magnetic material wide portion 249 in the radial direction is g. The dimension of the magnetic substance narrowing portion 248 in the radial direction is h. A half of the dimension of the bias magnetic field generation unit 21 in the circumferential direction is i. The dimension in the circumferential direction of the portion of the bias magnetic field generation unit 21 facing the magnetic material narrow portion 248 is j. In this case, the stator 2 is formed to satisfy g を 満 た す h × (i / j). The dimension g of the magnetic body wide portion 249 in the radial direction is the same as the dimension d in the radial direction at the outer end of the magnetic material radial outer side portion 241 in the circumferential direction. The other configuration is the same as that of the fourth embodiment.

In order for the magnetic member 24 not to be magnetically saturated, the dimension of the magnetic material radial direction outer portion 241 in the radial direction needs to have a length proportional to the length of the bias magnetic field generating portion 21 in the circumferential direction. The magnetic flux density of the bias magnetic field generation unit 21 is B. The magnetic flux density of the magnetic member 24 at the time of magnetic saturation is assumed to be B _s . In this case, h in the case of no magnetic saturation is calculated by the relationship of B × j ≦ B _s × h. The magnetic flux density B can be derived from the product of permeance and the magnetomotive force of the bias magnetic field generation unit 21. The permeance used here is the permeance when the gap length between the magnetic member 24 and the rotor 1 is minimum. The value g when the magnetic member 24 is not magnetically saturated is calculated by h, i and j.

The magnetic flux generated by the bias magnetic field generation unit 21 is represented by the product of the magnetic flux density B of the bias magnetic field generation unit 21 and the area of the surface of the bias magnetic field generation unit 21 facing outward in the radial direction. The magnetic flux interlinking with the magnetic substance radial direction outer part 241 is represented by the product of the magnetic flux density B ′ of the magnetic substance radial direction outer part 241 and the area of the surface facing the circumferential direction in the magnetic substance radial direction outer part 241. Here, it is assumed that the axial dimension of the bias magnetic field generation unit 21 and the axial dimension of the magnetic material radial direction outer portion 241 are equal. In this case, B × j = B ′ × h holds because the magnetic flux generated by the bias magnetic field generation unit 21 is equal to the magnetic flux linked to the magnetic material radial direction outer portion 241. Assuming that the magnetic flux density of the magnetic member 24 at the time of magnetic saturation is B _s , the magnetic flux density B ′ of the magnetic material radial outer side portion 241 does not generate magnetic saturation in the magnetic radial direction outer side 241. It needs to be Bs. Therefore, when magnetic saturation does not occur in the magnetic member 24, the dimension h of the magnetic narrow portion 248 in the radial direction is calculated by the relationship B × j ≦ B _s × h.

  The magnetic flux generated by the bias magnetic field generation unit 21 is represented by the product of the magnetic flux density B of the bias magnetic field generation unit 21 and the area of the surface of the bias magnetic field generation unit 21 facing radially outward. Therefore, the magnetic flux interlinking with the magnetic material wide portion 249 is larger than the magnetic flux interlinking with the magnetic material narrow portion 248. The magnetic flux density B ′ of the magnetic substance narrow portion 248 satisfies B ′ = (B × j) / h. Further, the magnetic flux density B ′ ′ of the magnetic material wide portion 249 satisfies B ′ ′ = (B × i) / g. The magnetic flux density B ′ ′ of the magnetic body wide portion 249 needs to be smaller than the magnetic flux density B ′ of the magnetic body narrow portion 248. Therefore, B ′ ′ ≦ B ′ holds. Thereby, the dimension g of the magnetic material large portion 249 in the radial direction is calculated by the relationship of g ≧ h × (i / j).

  As described above, according to the rotation angle detection device of the fifth embodiment of the present invention, ggh × (i / j) is satisfied. Thereby, weight reduction and cost reduction of a rotation angle detection apparatus can be achieved. Further, by reducing the weight of the rotation angle detection device, the durability of the rotation angle detection device against vibration can be improved. In addition, by making the magnetic member 24 smaller, it is possible to reduce the influence of noise from an external device such as a motor on the detection signal of the rotation angle detection device. In addition, weight reduction of the magnetic member 24 can be achieved without reducing the magnetic flux density passing through the magnetic member 24. Thus, the weight reduction of the magnetic member 24 can be achieved without reducing the detection signal of the magnetic flux density detection unit 22.

Sixth Embodiment
FIG. 20 is a plan cross-sectional view showing the main parts of a rotation angle detection device according to Embodiment 6 of the present invention. The magnetic member 24 is composed of a plurality of stacked steel plates. The stator 2 has a first crimp 25 provided at the magnetic material circumferential direction outer side portion 242 and fixing each of the plurality of steel plates. In addition, the stator 2 further includes a second crimp 26 provided at the center of the magnetic material radial direction outer side portion 241 in the circumferential direction and fixing each of the plurality of steel plates. A plurality of recesses 250 extending in the circumferential direction are formed on the outer surface of the radially outer portion 241 of the magnetic material in the radial direction. The second crimp 26 is disposed at a portion of the magnetic material radial direction outer portion 241 where the concave portion 250 is not formed. The other configuration is the same as that of the fifth embodiment.

  As described above, according to the rotation angle detection device according to the sixth embodiment of the present invention, the stator 2 is provided on the magnetic material circumferential direction outer portion 242, and the first crimp 25 for fixing each of the plurality of steel plates have. Thus, each of the stacked steel plates can be fixed without affecting the detection accuracy of the rotation angle detection device.

  Further, the stator 2 has a second crimping 26 provided at the center of the magnetic material radial direction outer side portion 241 in the circumferential direction and fixing each of the plurality of steel plates. Thus, each of the stacked steel plates can be fixed without affecting the detection accuracy of the rotation angle detection device.

  DESCRIPTION OF SYMBOLS 1 rotor, 2 stators, 11 rotating shafts, 12 uneven parts, 21 bias magnetic field generation parts, 22 magnetic flux density detection parts, 23 rotation angle calculation processing parts, 24 magnetic material members, 25 first caulking, 26 second caulking, 241 Magnetic material radial direction outer part, 242 Magnetic material circumferential outer part, 243 Magnetic material protrusion outer end, 244 Magnetic material protrusion inner end, 245 circumferential extension surface, 246 circumferential direction outward facing surface, 247 circumferential slope, 248 Small magnetic part, 249 large magnetic part, 250 concave.

Claims (7)

A rotor having an uneven portion made of a magnetic material on the outer peripheral surface;
A stator provided opposite to the uneven portion and having a bias magnetic field generation unit and a plurality of magnetic flux density detection units;
A magnetic material radial direction outer portion provided on the outer side of the bias magnetic field generation unit in the radial direction of the rotor and overlapped with the bias magnetic field generation unit in the radial direction and the bias magnetic field generation unit in the circumferential direction of the rotor And a magnetic member having a pair of magnetic outer circumferential portions sandwiching the magnetic members.
The uneven portion is formed to change by an X cycle with respect to a mechanical angle of 360 degrees in the circumferential direction, when X is an integer of 1 or more,
The plurality of magnetic flux density detection units are opposed to the concavo-convex portion with a gap therebetween, and are provided in one cycle of the concavo-convex portion at equal intervals along the circumferential direction,
The bias magnetic field generation unit is provided outside the respective magnetic flux density detection units in the radial direction, and is formed so as to overlap the respective magnetic flux density detection units in the radial direction and extend in the circumferential direction.
The inner end portion of the magnetic body circumferential direction outer side portion in the radial direction is provided inside the radial direction with respect to the inner end portion of the bias magnetic field generating portion in the radial direction.
An angle half of the angle between both ends of the bias magnetic field generation unit in the circumferential direction and the center of the rotor is a, and the bias magnetic field generation unit and the magnetic material circumferential direction outer side section in the circumferential direction The angle between the ends of the gap between the two and the center of the rotor is b, and the angle between the ends of the outer peripheral portion of the magnetic material in the circumferential direction and the center of the rotor is c If you
a + b> 180 / X, and a + b + c <360 / X
Rotation angle detection device that meets When α = a + b−180 / X, β = 360 / X− (a + b + c), and γ = a−180 / X,
α> β and γ> 0, or α <β and γ <0
The rotation angle detection device according to claim 1, wherein When α = a + b−180 / X and β = 360 / X− (a + b + c),
α = β
The rotation angle detection device according to claim 1, wherein The magnetic body circumferential direction outer side portion includes: a circumferential direction extending surface extending in the circumferential direction from an outer side surface in the radial direction in the magnetic body radial direction outer side portion; and a circumferential direction outward surface facing the outer side in the circumferential direction Have
The dimension in the radial direction at the outer end of the magnetic material radial direction outer portion in the circumferential direction is d, the dimension of the circumferential extension surface in the circumferential direction is e, and the circumferential direction in the radial direction When the dimension of the direction outward facing surface is f,
d ≦ e and f ≦ d
The rotation angle detection device according to any one of claims 1 to 3, wherein The magnetic body radial direction outer side portion is provided in a portion between the central portion and the outer side end portion in the circumferential direction in the magnetic body radial direction outer side portion, and extends in the circumferential direction in the radial outer side surface. A magnetic material narrow portion in which a recess is formed, and a magnetic material which is provided outside the magnetic material narrow portion in the circumferential direction, and a dimension in the radial direction is larger than a dimension of the magnetic material narrow portion in the radial direction With the large part of the body,
Let g be the size of the magnetic body wide portion in the radial direction, h be the size of the magnetic body narrow portion in the radial direction, and i be half the size of the bias magnetic field generating portion in the circumferential direction. In the case where the dimension in the circumferential direction of the portion of the bias magnetic field generation unit 21 facing the magnetic material narrow portion is j,
g ≧ h × (i / j)
The rotation angle detection device according to any one of claims 1 to 4, wherein The magnetic member is composed of a plurality of stacked steel plates,
The rotation according to any one of claims 1 to 5, wherein the stator further has a first crimp provided at the circumferential outer portion of the magnetic body and fixing each of the plurality of steel plates. Angle detector. The magnetic member is composed of a plurality of stacked steel plates,
The stator according to any one of claims 1 to 6, further comprising a second crimp provided at a central portion of the magnetic material radial direction outer portion in the circumferential direction and fixing each of the plurality of steel plates. The rotation angle detection device according to any one of the preceding claims.

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