JP5144960B2 - Magnetizing method and magnetizing apparatus for encoder - Google Patents

Description

  The present invention relates to an improvement in a magnetizing method and a magnetizing apparatus for an encoder in which N poles and S poles are alternately arranged at equal intervals in the circumferential direction on a detection surface, for example, incorporated in a rotational speed detecting device. .

  For example, in the case of an automatic transmission, it is necessary to detect the rotational speed of the rotary shaft in order to obtain the switching timing. In the case of an automobile, it is necessary to detect the rotational speed of the wheel in order to appropriately control the antilock brake system (ABS) and the traction control system (TCS). For this reason, rotating parts such as rotating shafts and wheels constituting such various mechanical devices are supported rotatably with respect to fixed parts such as a housing and a suspension device that do not rotate even in use, and the rotating parts rotate. 2. Description of the Related Art Conventionally, a rotation support device with a rotation speed detection device for detecting a speed has been widely used.

  4-6 has shown what was described in patent document 1 as a 1st example of the conventional structure of such a rotation support apparatus with a rotational speed detection apparatus. In the first example of this conventional structure, the outer ring 1 that is fitted and fixed to a housing (not shown) that does not rotate during use, and the outer ring 1 that is fitted and fixed to a rotating shaft (not shown) that rotates when used, An inner ring 2 (rotating member) that is rotatably supported via a plurality of balls 3 is provided on the inner diameter side of the outer ring 1. Further, a combination seal ring 4 serving as a sealing device is provided at the opening end of the space where the balls 3 are installed, which exists between the outer peripheral surface of the inner ring 2 and the inner peripheral surface of the outer ring 1. . This combination seal ring 4 is made of a metal plate such as a mild steel plate, a stainless steel plate, or the like, and a cored bar 5 having an L-shaped cross section and formed in an annular shape as a whole, and an elastomer such as rubber that is fixedly bonded to the entire circumference of the cored bar And another metal core (slinger) 7 formed of a metal plate such as a mild steel plate or a stainless steel plate and having an L-shaped cross section and a ring shape as a whole. And as shown in FIGS. 4-5, while the said metal core 5 is fitted and fixed to the edge part of the said outer ring | wheel 1, the said another metal core 7 is fitted and fixed to the edge part of the said inner ring | wheel 2, The leading edges of the plurality of seal lips constituting the elastic material 6 are brought into sliding contact with the surface of the separate cored bar 7 over the entire circumference.

  Further, of the cylindrical portion 8 and the annular portion 9 constituting the another core metal 7, an encoder together with the other core metal 7 is provided on the outer surface (the right side surface in FIGS. 4 to 5) of the annular portion 9. A ring-shaped encoder main body 11 constituting 10 is coupled and fixed concentrically with the other metal core 7. As shown in FIG. 6, on the outer side surface (right side surface in FIGS. 4 to 5) of the encoder main body 11, which is a detection surface, the N pole and the S pole are alternately arranged in the circumferential direction and the central angle. They are formed at equal intervals with a pitch P (magnetization pitch = 2P). Further, as shown in the figure, the boundaries between the N pole and the S pole arranged on the detection surface are parallel to the width direction (radiation direction) of the detection surface. Further, a detection portion of the sensor 12 supported by a portion that does not rotate even when the housing or the like is used is disposed in close proximity to a part of the detection surface in the circumferential direction. A magnetic sensing element such as a Hall IC, a Hall element, an MR element, or a GMR element is incorporated in the detection unit of the sensor 12.

  In the case of the first example of the conventional structure configured as described above, when the inner ring 2 that is externally fitted and fixed to the rotation shaft rotates, the vicinity of the detection portion of the sensor 12 is arranged in the vicinity of the N pole and S The poles pass alternately. As a result, the output of the sensor 12 changes at a frequency proportional to the rotational speed of the rotating shaft. Therefore, if the output of the sensor 12 is sent to a controller (not shown), the rotational speed of the rotating shaft can be detected, and various controls using the rotational speed can be appropriately performed.

  Next, FIG. 7 shows what is also described in Patent Document 1 as a second example of a conventional structure of a rotation support device with a rotation speed detection device. In the case of the second example of the conventional structure, a wheel (not shown) is supported and fixed on the inner diameter side of the outer ring 1a which is a stationary member coupled and fixed to a knuckle (not shown) that constitutes a suspension device for an automobile. A hub 13 that is a rotating member that rotates together with the wheels is rotatably supported via a plurality of balls 3 and 3. Also, the axially inner end of the space in which the balls 3, 3 are located between the inner peripheral surface of the outer ring 1a and the outer peripheral surface of the hub 13 ("inner" with respect to the axial direction is an automobile. 7-10, the right side of the vehicle in the width direction of the vehicle when assembled to the vehicle, and the right side of FIGS. The combination seal ring 4 and the encoder 10 are assembled in the same manner as in the first example of the conventional structure described above. Further, the detection part of the sensor 12 supported and fixed to a part of the knuckle or the outer ring 1 is made to face and oppose a part of the detected surface of the encoder 10 in the circumferential direction. In the case of the second example of the conventional structure configured as described above, when the output of the sensor 12 is sent to a controller (not shown) during driving of the automobile, the rotational speed of the wheel is detected and the ABS and TCS are appropriately controlled. It can be done.

  Next, FIGS. 8 to 9 show a third example of a conventional structure of a rotation support device with a rotation speed detection device, which is also described in Patent Document 1. FIG. In the case of the third example of the conventional structure, the cross-sectional shape of the annular cored bar 7a constituting the encoder 10a is different from that of the second example of the conventional structure described above. Further, a combination seal ring 4 (see FIG. 7) is provided at the inner end in the axial direction of the space where a plurality of balls 3 and 3 exist between the inner peripheral surface of the outer ring 1a and the outer peripheral surface of the hub 13. Instead, a cover 14 that blocks between the space and the external space is assembled to the inner end opening of the outer ring 1a. The cover 14 supports a sensor 12 whose detection portion is close to and opposed to the detection surface of the encoder 10a. Other configurations and operations are substantially the same as in the case of the second example of the conventional structure described above, and therefore, the same parts are denoted by the same reference numerals and redundant description is omitted.

  Next, FIG. 10 shows what is also described in Patent Document 1 as a fourth example of a conventional structure of a rotation support device with a rotation speed detection device. In the case of the fourth example of the conventional structure, the encoder 10b includes a cored bar 7b that is externally fitted and fixed to the inner end portion of the hub 13 and is formed into a circular shape with a cross-sectional crank shape, and a large diameter side of the cored bar 7b. It comprises a cylindrical encoder body 11b attached and fixed to the entire circumference of the inner peripheral surface of the cylindrical portion. N poles and S poles are alternately arranged at equal intervals in the circumferential direction on the inner circumferential surface of the encoder main body 11b, which is a detected surface. In addition, although illustration is abbreviate | omitted, the boundary of the N pole and S pole which are arrange | positioned on this to-be-detected surface is parallel with respect to the width direction (axial direction) of this to-be-detected surface. And the detection part of the sensor 12 supported by the cover 14 assembled | attached to the inner end part of the outer ring | wheel 1a is made to oppose and adjoin to a part of circumferential direction of this to-be-detected surface. Since the configuration and operation of the other parts are almost the same as in the case of the third example of the conventional structure described above, the same parts are denoted by the same reference numerals, and overlapping illustrations and descriptions are omitted.

  In each of the encoders 10, 10a and 10b incorporated in the conventional structures described above, the boundary between the N pole and the S pole existing on the detected surface is defined with respect to the width direction of the detected surface. They are parallel. On the other hand, in Patent Document 1, as shown in FIGS. 11 to 12, the boundary between the N pole and the S pole existing on the detected surface (outer peripheral surface) is defined in the width direction (axial direction) of the detected surface. Also shown are encoders 10c, 10d which are non-parallel to the. Each of these encoders 10c and 10d is used for measuring a load or the like acting on the rotation support device (see, for example, Patent Document 2).

By the way, the encoder 10 (10a to 10d) incorporated in each conventional structure as described above has an unmagnetized magnetic material that is a material of the encoder body 11 (11b to 11d) around the entire circumference of the core metal 7 (7a to 7d). After the members are coupled and fixed, the surface to be detected, which is part of the magnetic member, is magnetized. Conventionally, a one-shot magnetization method and an index magnetization method are known as magnetization methods at this time. Hereinafter, the one-shot magnetization method and the index magnetization method will be described.

  FIG. 13 is a schematic configuration diagram in the case where the one-shot magnetization method described in Patent Document 3 and the like is conventionally known. The magnetizing apparatus used in this one-shot magnetizing method sews between a magnetizing head 16 in which a large number of magnetized terminals 15 and 15 are arranged at equal intervals in the circumferential direction, and between the magnetized terminals 15 and 15. In this way, a magnetizing yoke 21 is provided, which is configured to include a continuous (one continuous) conductor 17 arranged in a meandering manner in the circumferential direction. When carrying out the one-shot magnetization method using such a magnetizing device, first, an encoder intermediate body 19 is prepared, in which a magnetic member 18 is coupled and fixed to the entire circumference of a core metal (not shown). To do. Then, as shown in the figure, the side surface (surface to be detected) of the magnetic member 18 is placed around the entire circumference with respect to the side surface of the magnetizing head 16 (tip surfaces of the magnetized terminals 15 and 15). Make contact in a concentric manner. In this state, on the basis of passing a magnetizing current through the conducting wire 17, the direction of entering / exiting between the tip surfaces of the magnetized terminals 15, 15 and the tip surfaces adjacent to each other in the circumferential direction is determined. Generate magnetic fluxes that are opposite to each other. Then, by passing these magnetic fluxes through the side surface of the magnetic member 18, N poles and S poles that are alternately arranged at equal intervals in the circumferential direction at the same time with respect to the entire circumference of the side surface of the magnetic member 18. And magnetized. In the illustrated example, the magnetized surface is an axial side surface. However, when the magnetized surface is a circumferential surface, one-shot magnetization can be performed by the same method.

  Next, FIG. 14 shows a first example of the index magnetization method described in Patent Document 4 and the like and conventionally known. The magnetizing apparatus used in this example includes a core member 20 having a pair of magnetizing heads 16a and 16b in which the tip surfaces of the magnetizing heads face each other, and proximal ends of these magnetizing heads 16a and 16b. A magnetized yoke 21a is provided that includes a wound coil (not shown). In order to implement the index magnetization method of this example using such a magnetizing device, first, an encoder intermediate body 19 is prepared in which a magnetic member 18 is coupled and fixed to the entire circumference of the cored bar 7. . Then, with the two magnetized heads 16a and 16b, the N pole and the S pole are arranged on the entire circumference of the side surface of the magnetic member 18 (the surface to be detected, the upper surface in FIG. 14). Magnetization is sequentially performed alternately at equal intervals with respect to the direction.

  Specifically, as shown in the drawing, each of the side surfaces of the magnetic member 18 (upper surface in FIG. 14) and the side surfaces of the core metal 7 (lower surface in FIG. 14) are aligned with each other. The front end surfaces of the two magnetized heads 16a and 16b are brought close to each other. In this state, only the encoder intermediate body 19 is rotated in the circumferential direction at a constant speed (while the magnetized yoke 21a is stationary), and the side surface of the magnetic member 18 and the side surface of the cored bar 7 are rotated. The adjacent opposing positions of the tip surfaces of the two magnetized heads 16a and 16b are continuously moved in the circumferential direction. At the same time, the front end surfaces of the two magnetized heads 16a and 16b are supplied to each of the coils based on flowing a periodic wave-shaped magnetizing current that alternately repeats forward and reverse flows at a period corresponding to the rotation speed. Between them, the magnetic member 18 and a part of the circumferential direction of the cored bar 7 are penetrated in the axial direction (vertical direction in FIG. 14), and the magnetic flux α is generated whose direction changes periodically and alternately. . As a result, one N-pole and one S-pole are formed on the entire circumference of the side surface of the magnetic member 18 alternately and at equal intervals in the circumferential direction. In the example shown in the figure, the magnetized surface is an axial side surface, but index magnetization can be performed in the same manner when the magnetized surface is a peripheral surface.

  Next, FIG. 15 shows a second example of the index magnetization method described in Patent Document 4 and the like and conventionally known. The magnetizing apparatus used in this example includes a ring-shaped core member 20a provided with a pair of magnetizing heads 16a and 16b at both ends thereof, and a coil 22 wound around an intermediate portion of the core member 20a. A magnetized yoke 21b is provided. In order to implement the index magnetization method of this example using such a magnetizing device, first, an encoder intermediate body 19 is prepared in which a magnetic member 18 is coupled and fixed to the entire circumference of the cored bar 7. . Then, by means of the two magnetized heads 16a and 16b, one set of N and S poles is formed on the entire circumference of the side surface of the magnetic member 18 (the surface to be detected, the upper surface in FIG. 15). Magnetization is sequentially performed in the circumferential direction.

  Specifically, as shown in the drawing, the two magnetized heads 16a and 16b are respectively located at two positions adjacent to each other in the circumferential direction on the side surface (upper surface in FIG. 15) of the magnetic member 18. Make the tip faces close to each other. Then, in this state, only the encoder intermediate body 19 is rotated in the circumferential direction at a constant speed (while the magnetized yoke 21b is stationary), and the two positions are continuously moved in the circumferential direction. . At the same time, the front end surfaces of the two magnetized heads 16a and 16b are caused to flow through the coil 22 by applying a pulse-wave-like magnetizing current that alternately repeats ON and OFF at a cycle corresponding to the rotation speed. In the meantime, generation and disappearance are alternately repeated, and magnetic flux α is generated that penetrates the two positions at the time of occurrence in directions opposite to each other in the direction of entering and exiting. As a result, one set of N and S poles is sequentially magnetized in the circumferential direction on the entire circumference of the side surface of the magnetic member 18. In the example shown in the figure, the magnetized surface is an axial side surface, but index magnetization can be performed in the same manner when the magnetized surface is a peripheral surface.

  Although not shown in the figure, the magnetic member constituting the encoder intermediate body is formed with three N poles and three S poles on the side surface or the peripheral surface (surface to be detected) and sequentially magnetized in the circumferential direction. An index magnetization method is also conventionally known (see, for example, Patent Document 3).

  Of the one-shot magnetization method and the index magnetization method as described above, in the case of the one-shot magnetization method shown in FIG. 13, the front end surfaces of the respective magnetization terminals 15, 15 constituting the magnetization head 16. The magnetic member 18 is magnetized in a state where the magnetic member 18 is in contact with the side surface of the magnetic member 18. For this reason, by adjusting the magnitude of the magnetizing current (about 5 to 10 kA), the magnetizing strength of the magnetic member 18 can be sufficiently increased (to the saturation level). However, in the case of the one-shot magnetization method shown in FIG. 13, the manufacturing error of the magnetizing head 16 (the shape error and pitch error of the magnetized terminals 15 and 15) is the same as that of the N pole and the S pole. It leads to the magnetization pitch error. For this reason, especially when the total number of these N poles and S poles is large, it becomes difficult to improve the magnetization pitch accuracy of these N poles and S poles.

  On the other hand, in the case of the index magnetization method shown in FIGS. 14 to 15 described above, while only the encoder intermediate body 19 is rotated at a constant speed in the circumferential direction, the pair of magnetization heads 16a and 16b A method is adopted in which N poles and S poles are formed on the side surface of the magnetic member 18 one by one (FIG. 14) or two poles (FIG. 15) and sequentially magnetized in the circumferential direction. For this reason, if the relationship between the rotation speed of the magnetic member 18 and the period of the magnetizing current is appropriately controlled, even if the total number of N poles and S poles is large, the both magnetized heads 16a, The magnetization pitch accuracy of the N pole and the S pole can be improved without being substantially affected by the manufacturing error of the magnetizing yoke 21a (21b) provided with 16b.

However, in the case of the index magnetization method shown in FIGS. 14 to 15 described above, when the magnetization is performed, the tip surfaces of the two magnetization heads 16a and 16b and the rotating encoder intermediate body 19 (magnetic member 18) are used. In addition, it is necessary to provide a gap for preventing interference (rubbing) between the side surface or the peripheral surface of the metal core 7). At the same time, the magnetizing current has to be lowered to about 1 to 10A. For this reason, even if the flow of the magnetic flux α is efficiently controlled by devising the shapes of the two magnetized heads 16a and 16b, the magnetization strength of the magnetic member 18 can be sufficiently increased (to the saturation level). Difficult (usually, it can be magnetized only to a level of 80 to 90% of the saturation level at the maximum). In addition, the number of turns of the magnetizing coil has to be increased as much as the magnetizing current is suppressed, and it becomes difficult to ensure the reliability and durability of the magnetizing coil. 14 is more efficient than the second example of the index magnetization method shown in FIG. 15 described above. In the first example of the index magnetization method shown in FIG. Since it can penetrate well, it is relatively easy to increase the magnetization strength of the magnetic member 18.

JP 2007-3223 A JP 2006-317420 A JP 2003-59718 A JP 2001-242187 A

  In view of the circumstances as described above, the present invention can increase the magnetization strength to the same extent as the above-described one-shot magnetization method, and can improve the magnetization pitch accuracy to the same extent as each index magnetization method described above. The invention was invented to realize a magnetizing method and a magnetizing device for an encoder.

An encoder that is a target of a magnetization method and a magnetization apparatus according to the present invention includes a mandrel and an encoder body. Of these, the core metal is formed in an annular shape as a whole, and is supported and fixed to a part of the rotating member concentrically with the rotating member during use. The encoder body is formed by bonding and fixing a magnetic member around the entire circumference of the core metal, and then magnetizing the magnetic member. The detected surface concentric with the core metal (axial side surface or The N pole and the S pole are alternately arranged at equal intervals in the circumferential direction on the detected surface.
Of the encoder magnetizing method and magnetizing apparatus according to the present invention, the encoder magnetizing method according to claim 1 includes an encoder intermediate body formed by coupling and fixing the magnetic member to the entire circumference of the core metal. After the construction, the tip surfaces of the two magnetizing heads constituting the magnetizing device are adjacent to each other in the circumferential direction among the surfaces to be detected, which are part of the magnetic member. And it is made to oppose and adjoin two positions where the rotation angle pitch between both is P (1/2 of the magnetization pitch 2P). Further, in this state, based on the intermittent rotation of only the encoder intermediate body by the rotation angle pitch P, the position where the tip surfaces of the two magnetized heads are in close proximity to the surface to be the detection surface. While moving the two positions intermittently by the rotation angle pitch P with respect to the circumferential direction, a magnetizing current is supplied to the magnetizing device only while the movement of the two positions is stopped. Based on this magnetizing current, a magnetic flux is generated between the tip surfaces of the two magnetizing heads so as to pass through the two positions in opposite directions with respect to the exit / entry direction. Further, each time the movement of the two positions stops, the surface to be the detected surface is obtained by alternately reversing the direction of the magnetic flux based on alternately reversing the direction of the magnetization current. N poles and S poles are alternately magnetized and formed at equal intervals with the rotation angle pitch P in the circumferential direction.
Particularly, in the case of the encoder magnetizing method of the present invention, the operation of rotating only the encoder intermediate body intermittently by the rotation angle pitch P is carried out by “1 rotation-1 rotation angle pitch P”. At the same time, in the stopped state before the first intermittent rotation of the encoder intermediate body, the first time at the two positions where the tip surfaces of the two magnetized heads are close to each other among the surfaces to be detected surfaces. Magnetization is performed, and after the intermittent rotation of the encoder intermediate body is performed by “1 rotation-1 rotation angle pitch P”, the two magnetizing heads of the surfaces to be detected among the surfaces to be detected are stopped. The final magnetization is performed at the two positions where the front end faces are close to each other. Further, the magnetizing current at the time of the last magnetization is made smaller than the magnetizing current at the other number of times of magnetization.
When the present invention is implemented, the magnitude of the rotation angle pitch P is determined in accordance with the total number of magnetic poles (N pole, S pole) provided on the detection surface of the encoder body. That is, when the total number of magnetic poles provided on the detected surface is K, the rotation angle pitch P is set to 360 (degrees) / K.

  When the encoder magnetizing method described in claim 1 as described above is performed, preferably, as described in claim 2, the magnetizing current is set to a magnitude in the range of 1 to 10 kA.

Of the encoder magnetizing method and magnetizing apparatus according to the present invention, the encoder magnetizing apparatus according to claim 3 is for carrying out the encoder magnetizing method according to claims 1 and 2 described above. A magnetizing device, which includes a rotation drive device, a magnetizing yoke, a magnetizing power supply device, and a centralized control device .
Among these, the rotary drive device intermittently rotates the encoder intermediate body by a central angle pitch P while supporting the encoder intermediate body formed by coupling and fixing a magnetic member to the entire circumference of the core metal.
The magnetizing yoke includes two magnetizing heads and a coil. Among these, the two magnetized heads are located at two positions, which are adjacent to each other in the circumferential direction and have a rotational angle pitch P among the surfaces to be detected, which are part of the magnetic member. Next, the respective front end faces are made to face each other. Then, based on passing a magnetizing current through the coil, the positions of the two locations penetrate between the tip surfaces of the two magnetizing heads in directions opposite to each other in the direction of entering and exiting. Generate magnetic flux in the corresponding direction.
In addition, the magnetizing power supply device allows the magnetizing current to flow through the coil only while the rotation of the encoder intermediate body is stopped, and the magnetizing power supply device every time the encoder intermediate body stops rotating. The direction of the current is reversed alternately.
Furthermore, the centralized control device executes control of the rotary drive device and control of the magnetized power supply device in association with each other. Thus, the operation of intermittently rotating only the encoder intermediate body by the rotation angle pitch P is performed by “1 rotation-1 rotation angle pitch P”. At the same time, in the stopped state before the first intermittent rotation of the encoder intermediate body, the first time at the two positions where the tip surfaces of the two magnetized heads are close to each other among the surfaces to be detected surfaces. Magnetization is performed, and after the intermittent rotation of the encoder intermediate body is performed by “1 rotation-1 rotation angle pitch P”, the two magnetizing heads of the surfaces to be detected among the surfaces to be detected are stopped. The final magnetization is performed at the two positions where the front end faces are close to each other. Further, the magnetizing current at the time of the last magnetization is made smaller than the magnetizing current at the other number of times of magnetization.

  In the case of the magnetizing method and magnetizing apparatus of the present invention as described above, the magnetic member constituting the encoder intermediate is magnetized in a state where the rotation of the encoder intermediate is stopped. For this reason, the magnetic member can be magnetized while flowing a magnetizing current having the same magnitude as in the case of the one-shot magnetization method shown in FIG. In addition, when the encoder intermediate body makes one rotation, each part of the surface to be detected (part where the N pole or S pole is to be disposed) present in a part of the magnetic member is twice each. It becomes a state of being magnetized one by one. For this reason, in the case of the present invention, the magnetization strength of the magnetic member can be increased to the same extent as in the case of the one-shot magnetization method. Further, since the magnetizing current can be increased, the number of turns of the magnetizing coil can be reduced, and the number of bending of the conducting wire constituting the magnetizing coil can be reduced, so that the reliability and durability of the magnetizing coil can be improved. .

  In the case of the present invention, only the encoder intermediate body is intermittently rotated at the rotation angle pitch P, and each time this rotation stops, the pair of magnetizing heads provide the detected surface. A method is adopted in which the power plane is magnetized in two places. For this reason, if the intermittent rotation control is performed with high accuracy, it is almost unaffected by the manufacturing error of the above-mentioned double magnetizing heads and the same as in the case of the index magnetizing method shown in FIGS. It is possible to improve the magnetization pitch accuracy of the N pole and the S pole provided on the surface to be the surface to be detected.

  1 to 3 show an example of an embodiment of the present invention. The feature of this example is that of an encoder intermediate body 19 which is an intermediate body of the encoder 10 shown in FIGS. Among them, the magnetic member 18 is in a method and apparatus for magnetizing. As shown in FIG. 1, the encoder magnetizing apparatus of the present example includes a rotation driving device 23, a magnetizing yoke 24, and a magnetizing power supply device 25.

Among these, the rotation drive device 23 includes a spindle device (high-precision bearing device) 26, a motor 27, a surface shake correction device 28, a rotation angle detection device 29, and a rotation control means 30. Of these, the spindle device 26 includes a main shaft (rotating shaft) (not shown) disposed in the vertical direction at the center. A jig 31 is held and fixed concentrically by a fixing chuck 32 at the upper end of the main shaft. When performing a magnetizing operation to be described later, the metal core 7 constituting the encoder intermediate body 19 is concentrically supported and fixed to the outer peripheral surface of the jig 31. The motor 27 is for rotating the main shaft and is provided below the spindle device 26. The surface shake correction device 28 is a side surface of the magnetic member 18 constituting the encoder intermediate body 19 (a surface to be detected, the upper surface in FIGS. This is provided between the spindle device 26 and the motor 27 for correcting the surface vibration (axial vibration due to rotation). The rotation angle detection device 29 is provided below the motor 27 for detecting the rotation angle of the main shaft. The rotation control means 30 executes control for intermittently rotating the main shaft by a rotation angle pitch P by the motor 27. When this control is executed, the rotation angle detecting device 29 detects the rotation. The signal (the rotation angle of the spindle) is used as a feedback signal.

  The magnetizing yoke 24 includes a core member 20b having a pair of magnetizing heads 16a and 16b, and a coil (not shown) wound around a part of the core member 20b. Then, as shown in FIGS. 3A, 3B, and 3C, which will be described later, based on passing a magnetizing current through the coil, between the front end surfaces of the magnetized heads 16a and 16b, A magnetic flux α passing between the two end faces can be generated, and the direction of the magnetic flux α can be reversed based on reversing the direction of the magnetization current. Such a magnetized yoke 24 is supported by a positioning device 33 that makes it possible to finely adjust the position of the magnetized yoke 24 in the directions of three axes (X axis, Y axis, Z axis) orthogonal to each other.

  The magnetization power supply device 25 includes a magnetization power supply main body 34 and a magnetization control means 35. Among these, the magnetized power source main body 34 generates a magnetizing current (for example, a capacitor-type power source) that flows through the coil constituting the magnetizing yoke 24, and determines the direction of the magnetizing current that flows through the coil. A switching function is provided. Further, the magnetization control means 35, when intermittent rotation control of the main shaft by the rotation control means 30 described above is performed, is applied to the coil by the magnetization power source main body 34 only while the rotation of the main shaft is stopped. The magnetizing current is allowed to flow, and every time the rotation of the main shaft stops, control for alternately reversing the direction of the magnetizing current is executed. In the case of this example, the control by the magnetization control means 35 and the control by the rotation control means 30 are executed in association with each other by the central control device 36 (personal computer). In the case of the magnetizing apparatus for the encoder of the present example, as another constituent element, when performing the magnetizing operation described below, the magnetizing device is formed on the side surface of the magnetic member 18 constituting the encoder intermediate body 19. A magnetic sensor 37 for quality inspection is provided for measuring the magnetization intensity of the magnetized portion. Further, in the case of this example, the detection signal of the magnetic sensor 37 is input to the magnetization control means 35, and this detection signal is used as a feedback signal when executing the above-described magnetization current control. I am trying to do it.

Next, a method of magnetizing the magnetic member 18 constituting the encoder intermediate body 19 using the encoder magnetizing apparatus as described above will be described. When the magnetic member 18 is magnetized, first, the encoder intermediate body 19 is set on a jig 31 as shown in FIG. Specifically, the metal core 7 constituting the encoder intermediate body 19 is concentric with the outer peripheral surface of the jig 31 with the side surface (surface to be detected) of the magnetic member 18 facing upward. Support and fix to. At the same time, as shown in FIG. 2, the tip surfaces of the two magnetizing heads 16a and 16b constituting the magnetizing yoke 24 are adjacent to each other in the circumferential direction of the side surfaces of the magnetic member 18, and both The rotation angle pitch between them is set to be close to and opposed to two positions. From the viewpoint of sufficiently securing the magnetization efficiency, the distance between these two positions and the tip surfaces of the two magnetized heads 16a and 16b (proximity facing distance) is such that these two positions and the two tip surfaces are the same. It is preferable to make it as small as possible without causing interference. In the case of this example, the distance is set to about 30 to 100 μm in consideration of the surface deflection of the side surface of the magnetic member 18 that occurs when the encoder intermediate body 19 described below rotates. Further, the magnetic sensor 37 has a side surface of the magnetic member 18 that is out of the two positions in the circumferential direction (a position slightly ahead of the two positions in the rotational direction described below). The detectors are placed close to each other.

  In this state, the centralized control device 36 executes the control by the rotation control means 30 and the control by the magnetization control means 35 in association with each other. That is, by executing the control by the rotation control means 30, the encoder intermediate body 19 is rotated intermittently by the rotation angle pitch P together with the main shaft constituting the spindle device 26. Then, based on this intermittent rotation, as shown in the order of (A) → (B) → (C) in FIG. 3, the adjacent opposing positions of the front end surfaces of the two magnetized heads 16 a and 16 b with respect to the side surface of the magnetic member 18. These two positions are intermittently moved by a rotation angle pitch P in the circumferential direction. At the same time as the control by the rotation control means 30, the control by the magnetization control means 35 is executed. Specifically, as shown in FIGS. 3A, 3B, and 3C, the magnetizing yoke 24 is only moved while the movement of the two positions (rotation of the encoder intermediate body 19) is stopped. A magnetizing current having a magnitude in the range of 1 to 10 kA is passed through the coil constituting the. Based on this magnetizing current, a magnetic flux α is generated between the tip surfaces of the two magnetizing heads 16a and 16b so as to penetrate the two positions in opposite directions with respect to the entering / exiting direction. Further, as shown in the order of (A) → (B) → (C) in FIG. 3, every time the movement of the two positions (rotation of the encoder intermediate body 19) stops, the direction of the magnetization current Are alternately reversed to reverse the direction of the magnetic flux α alternately.

That is, by executing the two controls as described above simultaneously, as shown in the order of (A) → (B) → (C) in FIG. Each time the movement is stopped while intermittently moving the two positions, which are adjacently facing positions of the tip surface of 16b, by the rotation angle pitch P in the circumferential direction, the two positions are set to the N pole and the S pole. The work of magnetizing the magnetic field and the work of magnetizing the S pole and the N pole are repeated alternately. In the case of this example, such an operation is terminated when the encoder intermediate body 19 is intermittently rotated by “1 rotation-1 rotation angle pitch P” (however, the first intermittent rotation is performed). The first magnetization is performed in the previous stop state). As a result, N poles and S poles are alternately magnetized and formed on the side surfaces of the magnetic member 18 at equal intervals with the rotation angle pitch P in the circumferential direction. At the same time, each of the poles (N pole and S pole) is magnetized twice. In addition, when performing the magnetization at the time of the last stop by the intermittent rotation of the encoder intermediate body 19 corresponding to “1 rotation-1 rotation angle pitch P”, the front side in the rotation direction among the two positions magnetized first. The second magnetization is performed at one place. However, at this time, of the two positions magnetized first, one position on the rear side in the rotation direction tends to be slightly demagnetized. For this reason, in order to suppress such demagnetization, the magnetization current at the time of magnetization at the time of the last stop is larger than the magnetization current at the time of magnetization at the time of other stops, Make it slightly smaller. In the case of this example, in parallel with the above-described magnetization operation, the magnetic sensor 37 measures the magnetization intensity of the magnetized portion of the side surface of the magnetic member 18. Perform an inspection. Thus, after performing the above-described magnetization operation, it is not necessary to separately perform a quality inspection of the magnetization intensity.

  As described above, in the case of the magnetizing method and magnetizing apparatus of the encoder of this example, the magnetic member 18 constituting the encoder intermediate body 19 is magnetized while the rotation of the encoder intermediate body 19 is stopped. For this reason, the magnetic member 18 can be magnetized while flowing a magnetizing current having the same magnitude (within a range of 1 to 10 kA) as in the case of the one-shot magnetization method shown in FIG. In addition, when the encoder intermediate body 19 makes one rotation, each part of the side surface of the magnetic member 18 (the part where the N pole or S pole is to be disposed) is magnetized twice. For this reason, in the case of this example, the magnetization intensity of the magnetic member 18 can be sufficiently increased (to the saturation level) as in the case of the one-shot magnetization method. In the case of carrying out this example, if the magnetizing current is increased, the durability of the magnetizing yoke 24 is impaired by that amount. Therefore, the magnitude of the magnetizing current is sufficient to saturate the magnetizing strength (saturation). It is preferable to make it as small as possible after satisfying the condition that can be increased. In order to improve the durability of the magnetized yoke 24, it is preferable to employ a cooling jacket structure that circulates cooling water inside the magnetized yoke 24.

  In the case of this example, only the encoder intermediate body 19 is intermittently rotated at the rotation angle pitch P, and each time this rotation stops, the pair of magnetizing heads 16a and 16b A method is employed in which the side surfaces of the member 18 are magnetized in two places. Therefore, if the intermittent rotation control is performed with high accuracy, even if the total number of N poles and S poles to be magnetized on the side surface of the magnetic member 18 is large, the manufacturing error of the magnetizing yoke 24 is affected. The magnetization pitch accuracy of the N pole and S pole can be improved satisfactorily (similar to the index magnetization method shown in FIGS. 14 to 15).

  Further, in the case of this example, during the intermittent rotation of the encoder intermediate body 19, rotational vibration occurs on the side surface of the magnetic member 18, and accordingly, the side surface of the magnetic member 18 and the both magnetized heads 16 a and 16 b When the proximity facing distance with the front end surface changes, the magnetization intensity of each magnetic pole (N pole, S pole) formed on the side surface of the magnetic member 18 varies. Such inconvenience occurs in the same manner in the conventional index magnetization method shown in FIGS. On the other hand, in the case of this example, the absolute value of the magnetization intensity of each of the magnetic poles (N pole, S pole) is obtained by performing magnetization with a magnetizing current similar to that in the one-shot magnetization method. Can be bigger. For this reason, the variation rate of the magnetization intensity | strength of each of these magnetic poles (N pole, S pole) can fully be reduced.

  In the above-described embodiment, the magnetizing operation at the time of manufacture is performed for the encoder 10 shown in FIGS. However, the present invention is not limited to this. For example, the magnetizing operation at the time of manufacture can be performed for the encoders 10a to 10d shown in FIGS.

  Incidentally, when the encoder magnetizing method and magnetizing apparatus of the present invention are implemented, the magnetic member constituting the encoder intermediate body (the material of the encoder main body) to be magnetized is not particularly limited. However, considering the bondability to the metal core constituting the encoder intermediate, the magnetic member contains about 70 to 92% by weight of magnetic powder, and a thermoplastic resin or rubber is used as a binder. A magnet compound can be suitably employed.

  In this case, ferrite magnetic powders such as strontium ferrite and barium ferrite, and rare earth magnetic powders such as neodymium-iron-boron, samarium-cobalt, and samarium-iron can be used as the magnetic powder. Furthermore, in order to improve the magnetic properties of ferrite, magnetic powder mixed with rare earth elements such as lanthanum can be employed. The reason why the content of the magnetic powder is preferably 70 to 92% by weight is that when the content is less than 70% by weight, the magnetic properties are inferior and the magnetic poles are multipolar in the circumferential direction with a fine pitch. This is because it becomes difficult to magnetize, and when the content is more than 92% by weight, the amount of the binder becomes too small, and the strength of the entire magnetic member is lowered. This is because molding becomes difficult and practicality is lowered.

In addition, when the thermoplastic resin is used as the binder, it is preferable to use an injection moldable one. Specifically, at least one soft segment of a hard segment made of a polyamide resin such as polyamide 6, polyamide 12, polyamide 612, polyamide 11, polyphenylene sulfide (PPS), polyamide 12 or the like, and a polyester component and a polyether component. It is preferable to employ a modified polyamide resin, which is a block copolymer, or a modified polyester resin, which is a similar block copolymer, using a polyester resin such as polybutylene terephthalate as a hard segment. . In addition, when there is a possibility that calcium chloride used as a snow melting agent and water are applied together in the usage environment, polyamide 12, polyamide 612, polyamide 11, polyphenylene sulfide (PPS), modified It is more preferable to use a polyamide 12 resin or a modified polyester resin as a resin binder. In addition, modified polyamide 12 resin and modified polyester resin improve flexural flexibility and crack resistance by adding as a binder to prevent cracking due to rapid temperature change (thermal shock) assumed in the usage environment. A mixture of any one of the modified polyamide 12 resins and the polyamide 12 or a mixture of the modified polyester resin and the polyester resin can be suitably employed. Further, as the binder for preventing the occurrence of cracks, a combination of the thermoplastic resin and an impact resistance improver such as fine particles of vulcanized rubber such as nitrile rubber and acrylic rubber may be employed.
Further, when the rubber is used as the binder, it is preferable to use nitrile rubber, acrylic rubber, hydrogenated nitrile rubber, fluorine rubber or the like having both oil resistance and heat resistance.

  In view of cost and oxidation resistance, it is most preferable to use ferrite magnetic powder as the magnetic powder. On the other hand, when using rare earth magnetic powders giving priority to magnetic characteristics, the oxidation resistance is lower than that of ferrite magnetic powders, so stable magnetic characteristics over a long period of time. In order to maintain the surface, it is preferable to provide a surface treatment layer on a portion of the surface of the magnetic member exposed to the periphery. As the surface treatment layer, for example, electric or electroless nickel plating, an epoxy resin coating film, a silicon resin coating film, a fluorine resin coating film or the like can be employed.

  In addition, as a material of the metal core constituting the encoder intermediate body, ferritic stainless steel (SUS430, etc.) that does not deteriorate the magnetic characteristics of the magnetic member and has a corrosion resistance of a certain level or more in relation to the use environment. In addition to martensitic stainless steel (SUS410, etc.), it is preferable to employ high corrosion resistance ferritic stainless steel, such as SUS434, SUS444, etc., which has been improved in corrosion resistance by adding Mo or the like.

  Moreover, it is preferable to provide fine unevenness on the surface of the core bar to be bonded to the magnetic member in order to improve the bonding force with the adhesive. In addition to mechanical methods such as a method by shot blasting and a method by transferring irregularities on the mold surface during press molding, the method of chemically etching the surface once surface-treated with an acid or the like can be used as a method for providing the unevenness. Can be adopted. Also, when the binder of the magnetic member is rubber, if an irregularity is provided on the surface of the magnetic member, the bonding surface with the cored bar, an adhesive enters the concave portion of the irregularity, and due to the anchor effect. Since the bonding force between the magnetic member and the cored bar becomes strong, it is more preferable.

  When the binder of the magnetic member is a thermoplastic resin that can be injection-molded, the encoder intermediate is injection-molded on a part of the core metal coated with an adhesive in the mold. Made by (insert molding). In this case, the adhesive is semi-cured to the extent that it is not detached and washed away by the molten material of the high-pressure magnetic member material (plastic magnet material, rubber magnet material, etc.). -Completely cured by heat from fluid rubber or in addition to secondary heating after molding. Adhesives that can be used in this case can be diluted with a solvent, and the curing reaction proceeds in almost two stages, such as phenol resin adhesives and epoxy resin adhesives, which have heat resistance, chemical resistance, and handling. This is preferable in that sufficient properties can be secured.

  Further, when the encoder intermediate is made by the above-described insert molding, and the magnetic member is a plastic magnet having a thermoplastic plastic as a binder, the magnetic member is molded from a plastic magnet material melted from the inner diameter thick portion. At the same time, it is preferable to use a disk gate type injection molding in which the metal flows into the mold at a high pressure and is rapidly cooled and solidified in the mold. If such a disk gate type injection molding is adopted, the molten resin spreads in a disk shape, and then flows into the mold corresponding to the inner diameter thick portion, thereby containing the flake-like magnetic powder contained therein. Are oriented parallel to the plane. In particular, the portion between the inner diameter part and the outer diameter part near the inner diameter thick part facing the detection part of the sensor has a higher orientation and is very close to the axial anisotropy oriented in the thickness direction. become. If a magnetic field is applied to the mold in the thickness direction during molding, the anisotropy becomes closer to perfection. Even if such a magnetic field molding is performed, if the gate is a disk gate other than a pin gate, for example, a pin gate, the orientation of the weld is completely different in the process of gradually increasing the resin viscosity toward solidification. It is difficult to form a crystallizing structure, which causes a decrease in magnetic properties and a possibility that cracks or the like may occur in a welded portion where mechanical strength is reduced for a long period of time.

  In the case where the binder of the magnetic member is rubber, if the magnetic member is molded by injection molding, it is preferable that the magnetic gate is also manufactured by the above-described disk gate type injection molding. On the other hand, if the magnetic member is molded by compression molding, the unvulcanized magnetic member formed into a sheet on the slinger is disposed in the mold (lower mold). The magnetic member is vulcanized and bonded to the slinger by placing a material and placing a mold (upper mold) on it.

尚、比較例１では、東洋磁気工業株式会社製の着磁ヨーク及び着磁電源を使用し、比較例２では、東洋磁気工業株式会社製の多極着磁装置に挟み込み着磁ヘッド１６ａ、１６ｂを取り付けたものを使用した。又、実施例では着磁ヘッド１６ｂに１巻きの、比較例２では着磁ヘッド１６ａに１００巻の、それぞれコイルを巻回した。又、比較例２で流す着磁電流に対しては、この着磁電流の大きさを、（着磁開始→）上昇→保持→下降（→着磁終了）の順に変化させる、台形制御を実施した。 Next, an experiment conducted for confirming the effect of the present invention will be described. In the experiment, various magnetization methods as shown in Table 1 below [Examples {magnetization method of the present invention (see FIGS. 1 to 3)}, Comparative Example 1 {conventional one-shot magnetization method (see FIG. 13) }, The magnetic member 18 constituting the encoder intermediate body 19 (see FIGS. 1 to 3) is magnetized by the comparative example 2 {index magnetizing method of the conventional sandwiching and magnetizing head system (see FIG. 14)}. Thus, after completing the encoder 10 (see FIGS. 4 to 7) in which a total of 86 magnetic poles (N poles, S poles) are provided on the axial side surface (inner diameter 60 mm, outer diameter 72 mm), which is the detected surface, The magnetic characteristics of the detected surface of the encoder 10 were examined.

In Comparative Example 1, a magnetizing yoke and magnetizing power source manufactured by Toyo Magnetic Industry Co., Ltd. are used. In Comparative Example 2, magnetizing heads 16a and 16b are sandwiched between multipolar magnetizing devices manufactured by Toyo Magnetic Industry Co., Ltd. The one with attached was used. In the example, one coil was wound around the magnetizing head 16b, and in the second comparative example, 100 coils were wound around the magnetizing head 16a. For the magnetizing current that flows in Comparative Example 2, trapezoidal control is performed in which the magnitude of the magnetizing current is changed in the order of (magnetization start →) rise → hold → fall (→ magnetization end). did.

The specifications of the encoder intermediate 19 used in the experiment are as follows.
<Specifications of cored bar 7>
Plate thickness 0.6mm. No. SUS430 of 2 finishes (JIS G 4305, arithmetic average roughness Ra of about 0.06 μm) is used as a base material. Only the joint surface of the magnetic member 18 is roughened to an arithmetic average roughness Ra of 1.3 μm by shot blasting.
<Specifications of the adhesive for joining the cored bar 7 and the magnetic member 18>
A 30% solid phenol resin adhesive (Metal Lock N-15, manufactured by Toyo Chemical Laboratories) consisting mainly of a novolak-type phenol resin is further diluted 3 times with methyl ethyl ketone, and applied to the slinger surface by dipping treatment. Then, after drying at room temperature for 30 minutes, it was made into the semi-hardened state by leaving it to stand in 120 degreeC for 30 minutes.
<Specifications of the magnetic member 18>
Material (magnet material for molding test): Strontium ferrite-containing 12 nylon-based anisotropic plastic magnet compound “FEROTOP TP-A27N” manufactured by Toda Kogyo Co., Ltd. (strontium ferrite content 90% by weight). By performing magnetic field shaping, the maximum energy product: 2.1 MGOe.
Molding method: A magnetic field is applied in the thickness direction (axial direction) during molding, and injection molding is performed by the disk gate method. The magnet is completely demagnetized by reversal demagnetization during cooling in the mold. In order to completely cure the adhesive, it was heated at 150 ° C. for 1 hour. Thickness 0.9mm after completion.

In the experiment, as the magnetic characteristics of the detected surface of the encoder 10 after completion as described above, the magnetic flux density (average) of the portion (measuring diameter 66 mm, air gap 1 mm) facing and close to the detected surface, The single pitch error (maximum value when descending) of the magnetic pole (N pole, S pole) provided on the detection surface was examined. The experimental results are shown in Table 2 below.

  From the experimental results shown in Table 2, according to the magnetization method (Example) of the present invention, the magnetic flux density can be increased to the same extent as that of the conventional one-shot magnetization method (Example 1), and the conventional index magnetization method can be achieved. It can be seen that the single pitch error can be reduced to the same extent as in the magnetic method (Example 2).

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the magnetizing apparatus of an encoder which shows one example of embodiment of this invention. The enlarged view which looked at the A section of FIG. 1 from the right side of this FIG. The B section enlarged view of FIG. The half part sectional view which shows the 1st example of a rotation support apparatus with a rotational speed detection apparatus. Part C enlarged view of FIG. The figure which shows the to-be-detected surface of the encoder integrated in this 1st example. Sectional drawing which shows the 2nd example of a rotation support apparatus with a rotational speed detection apparatus. Sectional drawing which shows the 3rd example. The D section enlarged view of FIG. Sectional drawing of the principal part which shows the 4th example of a rotation support apparatus with a rotational speed detection apparatus. The perspective view which shows the 1st example of the encoder which can be assembled | attached and used for the load measuring device of a rotation support apparatus. The perspective view which shows the 2nd example. The figure for demonstrating the one-shot magnetization method known conventionally. The figure for demonstrating the 1st example of the index magnetization method known conventionally. The figure for demonstrating the 2nd example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Outer ring 2 Inner ring 3 Ball 4 Combination seal ring 5 Core metal 6 Elastic material 7, 7a-7d Core metal 8 Cylindrical part 9 Circular ring part 10, 10a-10d Encoder 11, 11b-11d Encoder main body 12 Sensor 13 Hub 14 Cover 15 Magnetized terminal 16, 16a, 16b Magnetized head 17 Conductor 18 Magnetic member 19 Encoder intermediate 20, 20a, 20b Core material 21, 21a, 21b Magnetized yoke 22 Coil 23 Rotation drive device 24 Magnetized yoke 25 Magnetized Power supply device 26 Spindle device 27 Motor 28 Surface shake correction device 29 Rotation angle detection device 30 Rotation control means 31 Jig 32 Fixing chuck 33 Positioning device 34 Magnetization power source body 35 Magnetization control means 36 Central control device 37 Magnetic sensor

Claims (3)

A core metal and an encoder main body are provided, and the core metal is formed in an annular shape as a whole, and is supported and fixed to a part of the rotation member concentrically with the rotation member during use. The main body is formed by coupling and fixing a magnetic member to the entire circumference of the core metal, and then magnetizing the magnetic member. The main body has a detected surface concentric with the core metal, and the detected surface has N In order to manufacture an encoder in which poles and S poles are alternately arranged at equal intervals in the circumferential direction, after making an encoder intermediate body in which the magnetic member is coupled and fixed to the entire circumference of the core metal, The tip surfaces of the two magnetizing heads constituting the magnetizing device are adjacent to each other in the circumferential direction among the surfaces to be detected, which are part of the magnetic member, and between the two. In a state where the rotation angle pitch is in close proximity to two positions where P is P Based on the intermittent rotation of only the encoder intermediate body by the rotation angle pitch P, the positions of the two positions, which are adjacently facing positions of the front end surfaces of the two magnetized heads, with respect to the surface to be the detected surface, While the movement of these two positions is stopped while intermittently moving the rotation angle pitch P with respect to the circumferential direction, based on passing a magnetization current through the magnetizing device, A magnetic flux penetrating the two positions in opposite directions with respect to the entry / exit directions is generated between the front end surfaces, and the direction of the magnetizing current is alternately changed every time the movement of the two positions is stopped. By alternately reversing the direction of the magnetic flux based on the reversal, the N pole and the S pole are alternately arranged at equal intervals at the rotation angle pitch P in the circumferential direction on the surface to be detected. Magnetization formation That a magnetizing method of the encoder, the work to intermittently rotate only the encoder intermediates by rotation angle pitch P, along with performing only "1 rotation -1 rotational angle pitch P" component, the first encoder intermediate In the stopped state before the intermittent rotation of the encoder, the first intermediate magnetization is performed at the two positions where the tip surfaces of the two magnetized heads are close to each other among the surfaces to be detected. In the stop state after the intermittent rotation of "1 rotation-1 rotation angle pitch P" is performed, two positions where the tip surfaces of the two magnetized heads are close to each other among the surfaces to be detected surfaces The position is magnetized at the last time, and the magnetizing current at the time of the last magnetizing is made smaller than the magnetizing current at the other times of magnetizing. The encoder magnetizing method.   The method for magnetizing an encoder according to claim 1, wherein the magnetizing current is set to a magnitude within a range of 1 to 10 kA. A magnetizing device for carrying out the encoder magnetizing method according to any one of claims 1 to 2, comprising: a rotary drive device, a magnetizing yoke, a magnetizing power supply device, and centralized control. With the device ,
Among these, the rotary drive device is configured to intermittently rotate the encoder intermediate body by a central angle pitch P in a state where the encoder intermediate body formed by coupling and fixing a magnetic member to the entire circumference of the core metal is supported. ,
The magnetized yokes are located at two positions where the rotation angle pitch between the two adjacent to each other in the circumferential direction is P among the surfaces to be detected that are present in a part of the magnetic member. Two magnetizing heads that are close to each other, and a coil, and by passing a magnetizing current through the coils, the two locations are arranged between the tip surfaces of the two magnetizing heads. A magnetic flux in a direction corresponding to the direction of the magnetization current passing through the positions in opposite directions with respect to the exit / entry directions can be generated.
The magnetizing power supply device allows the magnetizing current to flow through the coil only while the rotation of the encoder intermediate is stopped, and the magnetizing current is reduced every time the encoder intermediate body stops rotating. The direction is reversed alternately ,
The centralized control device performs an operation of intermittently rotating only the encoder intermediate body by a rotation angle pitch P by executing the control of the rotary drive device and the control of the magnetized power supply device in association with each other. , For one rotation and one rotation angle pitch P, and in the stop state before the first intermittent rotation of the encoder intermediate body, the front ends of the two magnetized heads among the surfaces to be detected. First detection is performed at two positions with the surfaces facing each other, and the encoder intermediate body is intermittently rotated by “1 rotation-1 rotation angle pitch P”, and then the detected state is detected. The final magnetization of the two positions where the tip surfaces of the two magnetizing heads are closely opposed to each other among the surfaces to be the surface, and the magnetization current when performing the final magnetization, When performing other number of magnetizations It is intended to be smaller than the deposition current,
Encoder magnetizer.

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