JP2008232960A - Magnetizer of encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a magnetizer capable of making magnetic intensity of a detected surface of an encoder that can be made substantially uniform in the breadthwise direction of the surface. <P>SOLUTION: Both side rims corresponding to chevron-shaped bends in chevron-shaped leading end surfaces of a pair of magnetic yokes 15a and 15a constituting the magnetizer are defined as curves 16a and 16b, respectively. Use of such a structure alleviates concentration of a magnetic flux between regions corresponding to the chevron-shaped bends in both leading end surfaces, when a magnetic circuit for magnetization is formed between the leading end surfaces of the yokes 15a and 15a. Thus, the problem is solved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  According to the present invention, at least one state quantity of a relative displacement between a stationary member and a rotating member constituting a rotation supporting device such as a wheel supporting rolling bearing unit and an external force acting between these members is obtained. The present invention relates to an improvement in a magnetizing apparatus of an encoder used in combination with a sensor for measurement.

  The wheel of the automobile is rotatably supported by the suspension device by a rolling bearing unit such as a double row angular type. In addition, in order to ensure the running stability of automobiles, anti-brake brake system (ABS), traction control system (TCS), and electronically controlled vehicle stability control system (ESC) etc. Is used. In order to control such various vehicle running stabilization devices, signals representing the rotational speed of the wheels, acceleration in each direction applied to the vehicle body, and the like are required. In order to perform higher-level control, it may be preferable to know the magnitude of a load (for example, one or both of a radial load and an axial load) applied to the rolling bearing unit via a wheel.

  In view of such circumstances, Patent Document 1 describes an invention in which a special encoder is used to measure the magnitude of a load applied to a rolling bearing unit. 5 to 7 show an example of a state quantity measuring device for a rolling bearing unit described in Patent Document 1. FIG. One example of this conventional structure has a plurality of hubs 2 that are rotating members that rotate together with the wheels while being supported and fixed on the inner diameter side of the outer ring 1 that is a stationary member that does not rotate even when used. It is rotatably supported via rolling elements 3 and 3. A preload is applied to each of the rolling elements 3 and 3 together with contact angles that are opposite to each other (in the illustrated case, a rear combination type). In the illustrated example, a ball is used as the rolling element 3, but in the case of an automobile bearing unit that is heavy, a tapered roller may be used instead of the ball.

  Further, the inner end of the hub 2 ("inner" in the axial direction means the center side in the width direction of the vehicle when assembled to the automobile, and is the right side of Fig. 5. On the contrary, when the vehicle is assembled to the automobile, 5 is called “outside” with respect to the axial direction. The same applies to the whole of the present specification.) An annular encoder 4 is supported and fixed concentrically with the hub 2. . A pair of sensors 6 a and 6 b are supported and fixed inside a bottomed cylindrical cover 5 that closes the inner end opening of the outer ring 1, and the detection portions of both the sensors 6 a and 6 b are connected to the encoder 4. It is made to face and face the outer peripheral surface that is the surface to be detected.

  The encoder 4 is formed by combining a metal core 7 and an encoder body 8. Of these, the metal core 7 is composed of a magnetic metal plate such as a mild steel plate and is formed into a stepped cylindrical shape with a crank section in cross section. The large diameter cylindrical portion 9 and the small diameter cylindrical portion 10 are concentric with each other. And an annular portion 11 that connects the axial end edges of the cylindrical portions 9 and 10. Further, the encoder body 8 is formed by applying a cylindrical magnetic member (permanent magnet material, high coercive force material) as a material to the entire circumference of the inner half outer peripheral surface of the large-diameter cylindrical portion 9. It is constituted by magnetizing this magnetic member after fixing it concentrically (adhesion fixing, fixing by mold, etc.). S poles and N poles are alternately arranged at equal intervals in the circumferential direction on the inner half of the outer peripheral surface of the encoder body 8 in the axial direction, which is the detected surface. Then, the first characteristic in which the phase of the boundary between the S pole and the N pole gradually changes at a predetermined angle in a predetermined direction with respect to the axial direction of the outer peripheral surface in the outer half of the detected surface in the axial direction. The change unit 12 is used. On the other hand, the phase of the boundary between the S pole and the N pole on the inner half of the detected surface in the axial direction is the predetermined angle in the direction opposite to the predetermined direction with respect to the axial direction of the outer peripheral surface. The second characteristic changing unit 13 gradually changes at the same angle. Therefore, the S pole and the N pole have a “<” shape, with the central portion in the axial direction most protruding (or recessed) in the circumferential direction. Such an encoder 4 supports the hub 2 concentrically with the hub 2 by fitting the small-diameter cylindrical portion 10 constituting the cored bar 7 to the inner end of the hub 2 with an interference fit. It is fixed. Although the measurement accuracy is inferior, only the boundary of one of the characteristic change parts 12 and 13 is inclined with respect to the axial direction, and the boundary of the other characteristic change part is parallel to the axial direction. You can also do it.

  Further, magnetic detection elements such as a Hall IC, a Hall element, an MR element, and a GMR element are incorporated in the detection portions of the sensors 6a and 6b. Of these two sensors 6a and 6b, the detection part of one sensor 6a is in close proximity to the first characteristic changing part 12, and the detection part of the other sensor 6b is in close proximity to the second characteristic changing part 13. Yes. The positions where the detection parts of both the sensors 6 a and 6 b face both the characteristic changing parts 12 and 13 are the same in the circumferential direction of the encoder 4. Further, in a state where an axial load is not applied between the outer ring 1 and the hub 2, the most projecting portions in the circumferential direction at the central portion in the axial direction between the S pole and the N pole are the sensors 6a and 6b. The installation position of each member is restricted so that it exists just in the center position between these detection parts.

  In the case of an example of the conventional structure configured as described above, when an axial load acts between the outer ring 1 and the hub 2 (the outer ring 1 and the hub 2 are relatively displaced in the axial direction), both the sensors The phase at which the output signals 6a and 6b change is shifted. That is, in the neutral state in which an axial load is not acting between the outer ring 1 and the hub 2 and the outer ring 1 and the hub 2 are not relatively displaced, the detection units of the sensors 6a and 6b are It is opposed to the solid lines (a) and (b) in FIG. 7A, that is, the portion shifted from the most protruding portion by the same amount in the axial direction. Therefore, the phases of the output signals of the sensors 6a and 6b coincide as shown in FIG. On the other hand, when a downward axial load is applied to the hub 2 to which the encoder 4 is fixed as shown in FIG. 7A, the detecting portions of both the sensors 6a and 6b are shown in FIG. Opposed to broken lines b, b, i.e., portions different from each other in the axial direction from the most protruding portion. In this state, the phases of the output signals of the sensors 6a and 6b are shifted as shown in FIG. Further, when an upward axial load is applied to the hub 2 to which the encoder 4 is fixed as shown in FIG. 7A, the detecting portions of both the sensors 6a and 6b are connected to the chain line hub shown in FIG. , C, that is, the deviation in the axial direction from the most projecting portion opposes different portions in the opposite direction. In this state, the phases of the output signals of the sensors 6a and 6b are shifted in the opposite direction to the case of (B), as shown in (D) of FIG.

  Thus, in the case of the above-described example of the conventional structure, the phase of the output signals of the two sensors 6a and 6b is such that the acting direction of the axial load applied between the outer ring 1 and the hub 2 (the outer ring 1 and It shifts in the direction corresponding to the axial direction relative displacement with the hub 2. Further, the degree of the phase shift of the output signals of the sensors 6a and 6b due to the axial load (relative displacement) increases as the axial load (relative displacement) increases. Accordingly, the presence or absence of a phase shift between the output signals of the sensors 6a and 6b, and if there is a shift, the relative displacement in the axial direction between the outer ring 1 and the hub 2 is determined based on the direction and magnitude. The direction and size, and the direction and size of the axial load acting between the outer ring 1 and the hub 2 are determined. Note that the processing for calculating the relative displacement and load in the axial direction based on the phase difference existing between the output signals of the sensors 6a and 6b is performed by an arithmetic unit (not shown). For this reason, in the memory of this arithmetic unit, an expression or map representing the relationship between the phase difference and the relative displacement or load in the axial direction, which has been examined in advance by theoretical calculation or experiment, is stored.

  In the case of one example of the conventional structure described above, only one sensor set including a pair of sensors 6a and 6b in which the respective detection units are opposed to the first and second characteristic change units 12 and 13 is provided. Provided. On the other hand, Japanese Patent Application Nos. 2006-143097 and 2006-345849 disclose a structure in which a multi-directional displacement or external force is required by providing a plurality of sensor sets each composed of a pair of sensors. Yes.

  Next, two examples of magnetizing methods of the encoder 4 incorporated in the conventional structure described above will be described with reference to FIGS. In the two examples shown in FIGS. 8 to 9, prior to performing the magnetizing operation, a cylindrical shape, which is the material of the encoder body 8 (FIG. 6), is formed on the entire outer peripheral surface of the cored bar 7. The magnetic member 14 is attached and fixed. Further, when performing the magnetizing work, a pair of magnetized yokes 15 and 15 are used. The shapes (= cross-sectional shapes) of the front end surfaces of these two magnetized yokes 15 and 15 are each a “<” shape like the shapes of the S and N poles (FIG. 6) to be arranged on the detection surface of the encoder 4 It is said.

First, in the case of the first example of the magnetizing method shown in FIG. 8, when performing the magnetizing operation, the outer circumferential surface of the magnetic member 14 is circumferentially arranged at two portions adjacent to each other in the circumferential direction. The front end surfaces of the two magnetized yokes 15 and 15 whose directions with respect to each other are made to coincide with each other are made to face each other. In this state, when a current is passed through a coil (not shown) wound around each of the magnetized yokes 15 and 15, a magnetic circuit is formed between the tip surfaces of the magnetized yokes 15 and 15, and this magnetic circuit is formed. Magnetic flux constituting the circuit penetrates the two portions. As a result, a pair of “<”-shaped S poles and N poles constituting the detection surface is magnetized and formed at these two portions. Therefore, in the case of this example, the magnetic member 14 and the cored bar 7 are rotated continuously (or intermittently at every predetermined angle), and an appropriate value corresponding to this rotational speed (or rotating and stopping) is appropriate. At appropriate timing, the energization of the coil is alternately switched on and off. Thus, a pair of “<”-shaped S poles and N poles constituting the detected surface is sequentially magnetized in the circumferential direction on the entire outer peripheral surface of the magnetic member 14, and the encoder main body is formed. Complete 8
In the example shown in the figure, the number of magnetized yokes 15 that are used side by side in the circumferential direction is two, but may be three or more (for example, three to five).

Next, in the case of the second example of the magnetizing method shown in FIG. 9, when performing the magnetizing operation, a state in which a part of the circumferential direction of the magnetic member 14 and the cored bar 7 is sandwiched from both sides in a non-contact manner. Thus, the front end surfaces of the two magnetized yokes 15 and 15 whose directions in the circumferential direction coincide with each other are made to face each other. In this state, when a current is passed through a coil (not shown) wound around each of the magnetized yokes 15 and 15, a magnetic circuit is formed between the tip surfaces of the magnetized yokes 15 and 15, and this magnetic circuit is formed. Magnetic flux constituting the circuit penetrates a portion of the outer peripheral surface of the magnetic member 14 that is opposed to the distal end surface of the radially outer magnetizing yoke 15. As a result, one "<"-shaped S pole or N pole constituting the surface to be detected is magnetized and formed in this penetrating portion. Therefore, in the case of this example, while rotating the magnetic member 14 continuously (or intermittently at every predetermined angle), at an appropriate timing commensurate with this rotation speed (or rotation and stop), The ON / OFF of energization to the coil and the direction of energization to the coil are alternately switched. Thereby, the "<"-shaped S pole and N pole constituting the detected surface are alternately magnetized one by one in the circumferential direction on the entire circumference of the outer peripheral surface of the magnetic member 14, The encoder body 8 is completed.
In the illustrated example, the number of magnetized yokes 15 to be used is one, but the number of pairs may be two or more (for example, 2 to 5).

  By the way, the shape of the front end surface of both the magnetized yokes 15 and 15 used when each of the above-mentioned magnetizing methods is carried out is a "<" shape as shown in detail in FIG. In addition, the line shape of both side edges (portions surrounded by broken lines X and Y) corresponding to the bent portion of the “<” shape is a “<” shape with a corner (having a large curvature and a sharp point). It has become. For this reason, when each of the magnetization methods described above is carried out, if a magnetic circuit is formed between the front end surfaces of the two magnetized yokes 15, 15, the "<"-shaped bent of the two front end surfaces. It becomes easy for magnetic flux to concentrate between the parts corresponding to a part. As a result, the magnetization intensity of the detected surface of the encoder 4 magnetized by using both the magnetized yokes 15 and 15 (the magnetic flux density of the portion facing and close to the detected surface) is the width of the detected surface. It becomes particularly large at the center in the direction. Specifically, as shown in FIGS. 11 to 12A, the magnetic flux density of the portion that is close to and faces the detected surface is the highest in the center of the width direction (vertical direction in the figure) of the detected surface. Increasing and decreasing toward both ends of the detected surface in the width direction (the distribution of the magnetic flux density is a symmetric mountain distribution on both sides across the widthwise central portion of the detected surface).

  On the other hand, the output signals (FIG. 7) of the pair of sensors 6a and 6b that constitute the state quantity measuring device for the rolling bearing unit shown in FIGS. 5 to 7 pass through the detectors of these sensors 6a and 6b. Generated based on the magnetic flux density. This point will be described with reference to FIGS. Among these FIGS. 11 to 12, FIG. 11 shows a neutral state where an axial load is not acting between the outer ring 1 and the hub 2 (FIG. 5), and FIG. 12 shows a state between the outer ring 1 and the hub 2. One example of a state in which an axial load is acting is shown. Also, the sinusoidal curves in FIGS. 11-12 (B) indicate the magnetic flux density (change in magnitude) passing through the detection portions of the sensors 6a and 6b when the vehicle is running. Further, (C) in FIGS. 11 to 12 show output signals of both the sensors 6a and 6b. The output signal of (C) is obtained by converting the magnetic flux density of (B) into a binary signal of high potential and low potential by a Schmitt trigger circuit in which a predetermined hysteresis width W is provided at the threshold level S. It is. The hysteresis width W is provided to prevent erroneous detection of the magnetic flux density.

  Further, in the state shown in FIG. 11, that is, in the neutral state where the axial load is not applied, the detection portions of the pair of sensors 6a and 6b are detected surfaces as shown in FIG. It faces the position shifted from the central part in the width direction by the same amount in the width direction. For this reason, in the state shown in FIG. 11, as shown in FIG. 11B, the phases and amplitudes of the magnetic flux densities that pass through the detection portions of the sensors 6a and 6b coincide with each other. As a result, the phase difference existing between the output signals of the two sensors 6a and 6b becomes zero as shown in FIG. On the other hand, in the state shown in FIG. 12, that is, in the state where the axial load is applied, the encoder 4 moves in the width direction (upward in the illustrated example) as shown in FIG. Displace. Accordingly, the detection unit of one sensor 6a (upper in the illustrated example) faces a position near the center in the width direction of the detection surface, and the detection unit of the other sensor 6b (lower in the illustrated example). Is opposed to a position far from the center of the detected surface in the width direction. For this reason, in the state shown in FIG. 12, the phase of the magnetic flux density passing through the detection portions of the sensors 6a and 6b is shifted in the opposite direction as shown in FIG. The amplitude of the magnetic flux density passing through the detection unit 6a is increased, and the amplitude of the magnetic flux density passing through the detection unit of the other sensor 6b is decreased. As a result, as shown in FIG. 6C, the phases of the output signals of the two sensors 6a and 6b are shifted in the opposite directions, and a phase difference is generated between the two output signals. However, this phase difference has an error as compared with the phase difference that should originally occur. The reason for this is as follows.

That is, as shown in FIGS. 13A and 13B, the output signal β _{1 obtained} by converting the magnetic flux density α ₁ passing through the detection portion of the sensor 6a (6b) into a binary signal, and the same magnetic flux density. When the output signal β _{2 obtained} by converting α ₂ into a binary signal is compared, the phase of both output signals β ₁ and β ₂ is a phase difference between the two magnetic flux densities α ₁ and α _2. Even if there is no occurrence, only an amplitude difference is produced and they do not match. The reason for this is that, as shown in FIG. 5A, the angles representing the hysteresis width W of the Schmitt trigger circuit are different between the curves representing the two magnetic flux densities α ₁ and α ₂ . From this, the phase of the output signal of the sensor 6a (6b) can be obtained only by changing the amplitude of the magnetic flux density passing through the detection part of the sensor 6a (6b) even if the encoder 4 is not displaced in the width direction. I can see that it changes. Therefore, as in the example shown in FIGS. 11 to 12 described above, when the magnetic flux density of the portion close to and opposed to the detected surface of the encoder 4 is not uniform in the width direction of the detected surface. A phase change different from the actual displacement amount of the encoder 4 in the width direction is generated in the output signal of the sensor 6a (6b) by an amount corresponding to the degree of non-uniformity. As a result, as described above, there is an error in the phase difference between the output signals of both sensors 6a and 6b shown in FIG. . In order to measure the state quantity between the outer ring 1 and the hub 2 with higher accuracy, it is preferable to eliminate such an error.

  If the encoder is configured in an annular shape, the side surface in the axial direction of the encoder is a detection surface, and the detection portions of the pair of sensors are opposed to the detection surface in a state shifted in the radial direction, the above A relative displacement in the radial direction between the outer ring 1 and the hub 2 and a radial load applied between the outer ring 1 and the hub 2 are obtained. However, even when such a structure is adopted, there arises a problem regarding an error in the phase difference between the output signals of the pair of sensors as described above.

JP 2006-133045 A

  In view of the circumstances as described above, the present invention provides a magnetic flux in a portion that is close to and faces the detected surface of the encoder so as to suppress the occurrence of an error in the phase difference between the output signals of a pair of sensors. The invention was invented to realize a magnetizing apparatus capable of making the density distribution substantially uniform in the width direction of the detected surface.

The encoder to be magnetized by the magnetizing apparatus of the present invention is supported and fixed to the rotating member during use, and includes a detected surface concentric with the rotating member. The “<”-shaped S poles and N poles having a bent portion at the intermediate portion in the width direction of the detection surface are alternately arranged at equal intervals in the circumferential direction.
The encoder magnetizing apparatus of the present invention includes at least one pair of magnetizing yokes. Each of these magnetized yokes has a "<"-shaped tip surface, and a magnetic flux that forms a magnetic circuit formed between the tip surfaces of each other, among the materials for making the encoder, By passing through a portion of the surface to be detected in the circumferential direction, the “<”-shaped S pole or N-pole is magnetized and formed in the portion, and the “<” shape is In the tip surface of each of the two, the line shape of both side edges of the portion corresponding to the "<"-shaped bent portion is a curved shape with a corner, or a straight line shape parallel to the width direction of the detected surface. Yes.

  When the magnetizing apparatus for an encoder according to the present invention is implemented, it is preferable that, as described in claim 2, a surface to be detected among materials for making the encoder in a state in which the encoder is magnetized. The width dimension of the front end surface of each of the magnetized yokes in the width direction of the surface to be formed is made larger than the width dimension of the surface to be the detected surface.

  In carrying out the invention described in claims 1 and 2, preferably, as described in claim 3 (specifically, the magnetizing apparatus shown in FIG. 8 or FIG. 9 described above). The total number of magnetized yokes is less than the number of S poles and N poles provided on the detection surface of the encoder {for example, as shown in FIG. 8, the material for making the encoder When the magnetizing yokes are arranged only on one side in the radial direction, the total number of magnetizing yokes is about 2 to 5 (preferably 2 to 3), and as shown in FIG. When the magnetized yokes are arranged in pairs on both sides in the radial direction of the material to be manufactured, the number of magnetized yoke pairs is set to about 2 to 5 (preferably about 2 to 3)}. At the same time, while rotating the material for making the encoder intermittently or continuously, the magnetized yoke causes the S pole and the N pole to be placed on the surface to be detected among the materials. Are provided with the function of sequentially magnetizing.

  As described above, in the case of the encoder magnetizing apparatus of the present invention, the line on the both side edges of the portion corresponding to the "<"-shaped bent portion of the "<->-" shaped tip surface of each magnetized yoke. The shape is a curved shape with rounded corners or a linear shape parallel to the width direction of the detected surface. For this reason, when a magnetic circuit is formed between the tip surfaces of a pair of magnetized yokes to perform the magnetizing operation of the encoder, it corresponds to the above-mentioned "<"-shaped bent portion of both the tip surfaces. It is possible to sufficiently alleviate the concentration of the magnetic flux between the parts to be performed. Therefore, the magnetizing strength of the detected surface of the encoder magnetized using each of the magnetized yokes (the magnetic flux density at the portion facing and close to the detected surface) is substantially uniform in the width direction of the detected surface. it can. For this reason, when using the state quantity measuring apparatus of the rotary machine provided with this encoder, it can fully suppress that an error arises in the phase difference between the output signals of a pair of sensors. Therefore, the state quantity measurement by the state quantity measuring device can be performed with higher accuracy.

  When the present invention is implemented, if the structure described in claim 2 is adopted, the magnetization intensity of the detected surface of the encoder can be made more uniform in the width direction of the detected surface. The reason for this is as follows. That is, it is preferable that the magnetic flux entering and exiting from the tip surfaces of the pair of magnetizing yokes is in a state of being connected to each other. However, the magnetic flux entering and exiting at the both ends of the front end surfaces of the two magnetized yokes in the width direction of the surface to be detected among the materials for making the encoder is in the other direction as compared to the middle portion. Slightly increases the ratio of wrapping around (disconnecting each other). For this reason, the magnetic flux density between the both end portions of the front end surfaces of the two magnetized yokes is slightly smaller than the magnetic flux density between the intermediate portions. On the other hand, if the structure described in claim 2 is adopted, when performing the magnetizing operation of the encoder, the surface to be detected (or the back surface) of the material for making the encoder is to be detected. Only the intermediate part of the front end face of each of the magnetized yokes can be made to face each other (both ends are not made to face each other). For this reason, the surface to be detected can be magnetized by a magnetic flux formed between the front end surfaces of the pair of magnetized yokes and having a high density uniformity. Therefore, the magnetization intensity of the detected surface of the encoder can be made more uniform in the width direction of the detected surface.

  Further, when the present invention is implemented, if the structure described in claim 3 is adopted, the S poles and N poles arranged on the detection surface of the encoder have the same magnetization intensity, and these S poles and It becomes easy to improve the pitch accuracy of N poles (single, adjacent, cumulative). The reason for this is as follows. That is, when carrying out the present invention, a structure for performing simultaneous magnetization of the entire surface to be detected by using magnetizing yokes having the same number or logarithm as the S and N poles disposed on the surface to be detected. Can also be adopted. However, when such a structure is adopted, the number of magnetized yokes increases, so the variation in dimensions, the pitch accuracy of the arrangement, and the state of the coil wound around (impedance and positioning) for each of these magnetized yokes. , Each becomes difficult to regulate with high accuracy. Therefore, it is difficult to make the magnetization strengths of the S pole and N pole equal to each other and to improve the pitch accuracy of the S pole and N pole. On the other hand, if the structure described in claim 3 is adopted, the number of magnetized yokes can be reduced, so that it becomes easy to perform the above-described regulation with high accuracy. Therefore, it becomes easy to make the magnetization intensity of the S pole and N pole equal to each other and to improve the pitch accuracy of the S pole and N pole.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention corresponding to claims 1 to 3. The feature of this example is that the shape (= cross-sectional shape) of the tip surfaces of the pair of magnetizing yokes 15a, 15a constituting the magnetizing device is devised. Since the structure and operation of the other parts are almost the same as those of the magnetizing apparatus shown in FIG. 8, the overlapping illustrations and explanations are omitted or simplified. The description will focus on the parts different from the magnetizing apparatus shown in FIG.

FIG. 1 shows a magnetizing work state of the encoder 4 (FIG. 2). In the case of this example, the side edges of the portions corresponding to the "<"-shaped bent portions of the "<"-shaped end surfaces of the pair of magnetized yokes 15a, 15a are respectively curved portions 16a, 16b. It is said. That is, the line shape on both side edges of the portion is a curved shape with a corner. At the same time, the width dimension W _15a of the two magnetized yokes 15a and 15a with respect to the width direction (vertical direction in FIG. 1) of the outer peripheral surface of the magnetic member 14, which is the material of the encoder body 8 (FIG. 2), is larger (W _15a> W ₁₄₎ than the width W ₁₄ of the outer peripheral surface of the member 14. And only the intermediate part of the front end surface of both said magnetized yokes 15a and 15a is made to oppose with respect to the outer peripheral surface of the said magnetic member 14 (it is not made to oppose both ends).

  As described above, in the case of this example, both side edges of the portions corresponding to the "<"-shaped bent portions of the "<"-shaped end surfaces of the pair of magnetized yokes 15a, 15a are respectively The curved portions 16a and 16b are used. For this reason, when a magnetic circuit is formed between the front end surfaces of both the magnetized yokes 15a, 15a, a magnetic flux is generated between the two end surfaces corresponding to the "<"-shaped bent portions. Can be relaxed enough. On the other hand, as described above, it is preferable that the magnetic fluxes entering and exiting from the front end surfaces of the two magnetized yokes 15a and 15a are connected to each other. However, at both end portions of the front end surfaces of the two magnetized yokes 15a, 15a, the rate at which the entering and exiting magnetic flux wraps around in the other direction (cannot be connected to each other) is slightly higher than that at the intermediate portion. For this reason, the magnetic flux density between the both end portions of the front end surfaces of the magnetized yokes 15a, 15a is slightly smaller than the magnetic flux density between the intermediate portions. On the other hand, in the case of this example, only the intermediate part of the front end surfaces of the magnetized yokes 15a and 15a is opposed to the outer peripheral surface of the magnetic member 14 (both ends are not opposed). . For this reason, only the magnetic flux with high uniformity of density formed between the intermediate portions of the front end surfaces of the two magnetized yokes 15a, 15a can be penetrated through the outer peripheral surface of the magnetic member 14.

  Therefore, according to the encoder magnetizing apparatus of the present example as described above, as shown in the right part of FIG. 2A, the magnetizing strength of the detected surface of the encoder 4 (proximity facing this detected surface). Magnetic flux density of the portion to be detected) can be made substantially uniform with respect to the width direction (the vertical direction in the figure) of the detected surface. For this reason, when an axial load acts between the outer ring 1 and the hub 2 (see FIG. 5), as shown in FIG. 2A, a pair of sensors 6a with respect to the detected surface of the encoder 4, Even when the opposing position of the detection part 6b deviates from the neutral position, the amplitudes of the magnetic flux densities passing through the detection parts of both the sensors 6a and 6b can be made substantially equal to each other, as shown in FIG. Therefore, it is possible to sufficiently suppress the occurrence of an error based on the amplitude difference in the phase difference between the output signals of the sensors 6a and 6b as shown in FIG. That is, when the case of FIG. 2 is compared with the case of FIG. 12, the opposing positions of the detection portions of the pair of sensors 6a and 6b with respect to the detection surface of the encoder 4 shown in FIG. Are the same as each other, but the magnitudes of the phase differences between the output signals of these sensors 6a and 6b shown in (C) are different from each other. The reason for this is that the error based on the variation in the density of the magnetic flux passing through the detectors of the two sensors 6a and 6b included in this phase difference is relatively large in the case of FIG. This is because the number is sufficiently small in the case of 2. For this reason, if the encoder 4 magnetized by the magnetizing apparatus of this example is used, the relative displacement in the axial direction between the outer ring 1 and the hub 2 and the action between the outer ring 1 and the hub 2 are exerted. It can be seen that the axial load can be measured with higher accuracy.

[Second Example of Embodiment]
Next, FIG. 3 shows a second example of an embodiment of the present invention corresponding to claims 1 and 3. Unlike the case of the first example described above, in this example, the width dimension W _15b of the pair of magnetized yokes 15b, 15b is the same as the width dimension W ₁₄ of the outer peripheral surface of the magnetic member 14 (W _15b = is the W _14). The entire front end surfaces of the magnetized yokes 15b and 15b are opposed to the outer peripheral surface of the magnetic member 14. Thus, in the case of the magnetizing apparatus of this example, not only the intermediate part of the front end surfaces of the two magnetized yokes 15b and 15b but also the both end parts are opposed to the outer peripheral surface of the magnetic member 14. Therefore, as compared with the case of the magnetizing apparatus of the first example described above, the degree to which the magnetizing intensity of the detected surface of the encoder 4 (FIG. 2) can be made uniform in the width direction is somewhat lower. However, as compared with the magnetizing apparatus shown in FIG. 8, the degree to which the magnetizing intensity of the detection surface of the encoder 4 can be made uniform in the width direction can be sufficiently increased. Other configurations and operations are the same as those of the first example described above.

[Third example of embodiment]
Next, FIG. 4 shows a third example of the embodiment of the present invention corresponding to claims 1 to 3. In the case of this example, both side edges of the portion corresponding to the "<"-shaped bent portion of the "<"-shaped end surface of the magnetized yoke 15c constituting the magnetizing device are magnetized. The straight portions 17a and 17b are parallel to the width direction of the detected surface of the power encoder 4 (see FIG. 2). That is, the line shape on both side edges of the portion corresponding to the bent portion is a straight line shape with corners. In addition, both ends of both the straight portions 17a and 17b and the ends of both side edges (oblique edges) of the portions corresponding to the respective sides of the "<" shape are smoothly passed through the curved portions 18a and 18b, respectively. It is continuous. Other configurations and operations are the same as those in the first and second examples described above.

  In each of the above-described embodiments, the present invention is applied to the magnetizing apparatus shown in FIG. 8, but the present invention can also be applied to the magnetizing apparatus shown in FIG. Further, the boundary between the S pole and the N pole provided on the detected surface is inclined only at one characteristic changing portion and parallel to the other characteristic changing portion with respect to the width direction of the detected surface. It can also be applied to a magnetizing device. Furthermore, in order to make it possible to measure a radial load, the present invention can be applied to an encoder magnetizing device (axially opposed magnetizing) having an annular detection surface.

The figure which looked at the state which magnetizes an encoder by a pair of magnetizing yokes which shows the 1st example of embodiment of this invention from the radial direction outer side of this encoder. The figure which shows the production | generation process of the output signal of a pair of sensor facing this encoder and the encoder magnetized by the magnetizing yoke of this 1st example in the state where the axial load acted. The figure similar to FIG. 1 which shows the 2nd example of embodiment of this invention. The figure which shows the front end surface of the magnetizing yoke which shows the 3rd example. Sectional drawing which shows one example of the conventional structure regarding the state quantity measuring apparatus of a rolling bearing unit. The perspective view which shows a part of encoder. The diagram for demonstrating the state from which the output signal of a pair of sensor changes based on an axial load. The figure which looked at the 1st example of the magnetizing method of the encoder proposed conventionally from the axial direction of this encoder. The figure similar to FIG. 8 which shows the said 2nd example. The figure which shows the front end surface of the conventional magnetizing yoke. The figure which shows the production | generation process of the output signal of a pair of sensor made to oppose this encoder and the encoder magnetized by the conventional magnetizing yoke in a neutral state. Similarly, the figure shown in the state where the axial load acted. The diagram for demonstrating that the phase of the output signal of this sensor shifts | deviates because the amplitude of the magnetic flux density which passes the detection part of a sensor changes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Hub 3 Rolling element 4 Encoder 5 Cover 6a, 6b Sensor 7 Core metal 8 Encoder main body 9 Large diameter cylindrical part 10 Small diameter cylindrical part 11 Circular ring part 12 First characteristic change part 13 Second characteristic change part 14 Magnetic Members 15, 15a to 15c Magnetized yokes 16a, 16b Curved portions 17a, 17b Linear portions 18a, 18b Curved portions

Claims (3)

  It is supported and fixed to the rotating member at the time of use, and has a detected surface concentric with the rotating member, and each of the detected surfaces has a bent shape at a middle portion in the width direction of the detected surface. An encoder magnetizing apparatus in which S poles and N poles are alternately arranged at equal intervals in the circumferential direction, and includes at least one pair of magnetizing yokes. The circumferential surface of the surface to be the detected surface of the material for making the encoder is made of magnetic flux that forms a magnetic circuit formed between the front end surfaces and has a U-shaped tip surface. By passing through a part in the direction, the "<"-shaped S-pole or N-pole is magnetized in that part, and the "<"-shaped Alignment of both side edges of the part corresponding to the bent part of A balanced curve shapes of square, or magnetizing apparatus of an encoder which is parallel to the straight line shape with respect to the width direction of the sensed surface.   In the state of performing the magnetizing work of the encoder, the width dimension of the front end surface of each magnetized yoke with respect to the width direction of the surface to be detected among the materials for making the encoder becomes the detected surface. The encoder magnetizing apparatus according to claim 1, wherein the magnetizing apparatus is larger than a width dimension of the power surface.   The total number of magnetizing yokes is smaller than the number of S poles and N poles provided on the detection surface of the encoder, and each of the magnetizing yokes is rotated while intermittently or continuously rotating the material for manufacturing the encoder. The encoder magnetizing apparatus according to claim 1 or 2, wherein the yoke has a function of sequentially magnetizing and forming the S pole and the N pole on the surface to be detected of the material.

Images