JP2012189191A - Rolling bearing unit with encoder and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a structure for reducing a residual magnetic flux flow volume when a residual magnetic flux coming out of an axial inside end surface of an inner race 2 flows to a detector 24 side of a sensor 16, thereby deteriorating an adverse effect on the magnetic flux which enters and leaves a detected surface of an encoder 5 and then passes through the detector 24 of the sensor 16, and to provide a method for manufacturing the same.SOLUTION: In a state prior to the coupling of a hub 1 and the inner race 2, a polarity (S polarity) of the residual magnetism of an axial inside end surface of the hub 1 and a polarity (N polarity) of the residual magnetism of the axial inside end surface of the inner race 2 are made different from each other. In this state, the hub 1 and the inner race 2 are coupled to each other, thereby completing a structure where the polarities of the residual magnetisms on the axial inside end surfaces of the hub 1 and inner race 2 are different from each other. As a result, the magnetic flux leaving the axial inside end surfaces of the inner race 2 is induced to a hub 1 side.

Description

  The present invention relates to, for example, a rolling bearing unit with an encoder that supports a wheel of an automobile rotatably with respect to a suspension device and can detect the rotational speed of the wheel, and an improvement of the manufacturing method thereof.

  A rolling bearing unit is used to rotatably support the wheels of the automobile with respect to the suspension system. In order to control the anti-lock brake system (ABS) and the traction control system (TCS), it is necessary to detect the rotational speed of the wheel. For this reason, the rolling bearing unit with an encoder in which the encoder constituting the rotational speed detecting device is assembled to the rolling bearing unit is supported rotatably with respect to the suspension device, and the rotational speed of the wheel is detected. Is generally done.

  FIG. 4 shows an example of a conventional structure of a rolling bearing unit with an encoder used for such a purpose. This encoder-equipped rolling bearing unit includes a hub 1 that is a shaft member, an inner ring 2, an outer ring 3, a plurality of rolling elements 4 and 4, and an encoder 5. Of these, the outer end in the axial direction of the outer peripheral surface of the hub 1 ("outer" with respect to the axial direction means the outer side in the width direction of the vehicle when assembled to the automobile, and the left side in Figs. “Inner” means the center side in the width direction of the vehicle, and on the right side of FIGS. 1 and 4) A rotating side flange 6 for supporting the wheel is provided on the side portion, and the first inner ring is also provided in the middle in the axial direction. The track 7a is formed with a small-diameter step portion 8 having an outer diameter smaller than that of the portion where the first inner ring raceway 7a is formed. The inner ring 2 is formed with a second inner ring raceway 7b on the outer peripheral surface, and is fitted on the small-diameter step portion 8 with an interference fit.

  The outer ring 3 is formed with a stationary flange 9 on the outer peripheral surface for coupling and fixing to the suspension device, and first and second outer ring raceways 10a and 10b on the inner peripheral surface. A plurality of rolling elements 4, 4 are provided between the first and second outer ring raceways 10a, 10b and the first and second inner ring raceways 7a, 7b. Further, in this state, the cylindrical portion 11 provided at the inner end portion in the axial direction of the hub 1 is caulked by plastically deforming a portion protruding from the inner end surface in the axial direction of the inner ring 2 radially outward. Part 12 is formed. The caulking portion 12 suppresses the inner end surface of the inner ring 2 in the axial direction so that the inner ring 2 is coupled and fixed to the hub 1 and an appropriate preload is applied to the rolling elements 4 and 4. Yes. In the illustrated example, balls are used as the rolling elements 4 and 4. However, in the case of a wheel support bearing unit for automobiles that is heavy in weight, a tapered roller may be used.

  The encoder 5 is externally fitted and fixed to the inner end of the inner ring 2 in the axial direction. The encoder 5 includes a core bar 13 and an encoder body 14. Of these, the core 13 is made of a magnetic metal plate such as a mild steel plate or a magnetic stainless steel plate and is formed into an annular shape with an L-shaped cross section, and is fitted on the inner end in the axial direction of the inner ring 2 by an interference fit. is doing. The encoder body 14 is a ring-shaped multipolar magnet, and is fixed to the inner side surface in the axial direction of the metal core 13 over the entire circumference. S poles and N poles are alternately arranged at equal pitches in the circumferential direction on the outer surface of the encoder body 14 in the axial direction, which is the detected surface. In addition, the inner end opening of the outer ring 3 in the axial direction is made of a nonmagnetic metal plate such as a nonmagnetic stainless steel plate or an aluminum alloy plate, or a nonmagnetic material such as a high-functional resin, and is formed in a petri dish as a whole. By attaching the cover 15 which has been made, the opening is closed. In this state, the detected surface of the encoder 5 is in close proximity to the bottom plate portion of the cover 15.

  When the rolling bearing unit with an encoder as described above is used, the stationary side flange 9 constituting the outer ring 3 is coupled and fixed to a suspension device, and the wheel is supported and fixed to the rotating side flange 6 constituting the hub 1. Further, the detection unit 24 of the sensor 16 supported and fixed to a part of the vehicle body is brought close to and opposed to the detection surface of the encoder 5 through the bottom plate portion of the cover 15. The detection unit 24 of the sensor 16 is constituted by a magnetic detection element such as a Hall IC, a Hall element, an MR element, or a GMR element. When the wheel rotates in this state, the S pole and the N pole provided on the detection surface of the encoder 5 alternately pass through the vicinity of the detection unit 24 of the sensor 16. As a result, the direction of the magnetic flux passing through the detection unit 24 of the sensor 16 changes alternately, and the output of the sensor 16 changes. The frequency at which the output of the sensor 16 changes in this way is proportional to the rotational speed of the wheel. Therefore, if the output of the sensor 16 is sent to a controller (not shown), the ABS and TCS can be appropriately controlled.

  By the way, when making each bearing ring member (the hub 1, the inner ring 2, the outer ring 3) constituting the rolling bearing unit with an encoder as described above, among the surfaces of these bearing ring members (1 to 3), A predetermined portion such as the fitting surface of each of the tracks 7a, 7b, 10a, 10b, the small-diameter step portion 8, and the cover 15 is subjected to grinding for improving surface accuracy and surface roughness. The grinding process at this time is usually performed as shown in FIG. That is, the target ring member (in the illustrated example, the hub 1) is magnetically attracted to the end surface of the backing plate 17 fixed to the tip of the rotational drive shaft (not shown). At the same time, the race 18 is positioned in the radial direction by bringing the shoe 18 into sliding contact with the outer peripheral surface of the race member 1. In this state, a predetermined portion of the surface of the bearing ring member (1) is ground with the rotating grindstone 19 while rotating the bearing ring member (1) together with the rotation drive shaft. The same applies to the case where the target ring member is the inner ring 2 or the outer ring 3.

  When the grinding process as described above is performed, each of the track ring members (1 to 3) is magnetized in the axial direction based on the magnetic attraction to the backing plate 17, and has a residual magnetism in the axial direction. It becomes. For this reason, as described in Patent Document 1, when each of the bearing ring members (1 to 3) is used as it is and the above-described rolling bearing unit with an encoder is assembled, each of the bearing ring members (1 to 1) is assembled. The magnetic flux generated in the surroundings by the residual magnetism of 3) adversely affects the magnetic flux that enters and exits the detection surface of the encoder 5 and passes through the detection unit 24 of the sensor 16 (an effect that changes the density and distribution). There is a possibility that the reliability of rotation speed detection is lowered. In addition, after grinding each said bearing ring member (1-3), before removing these each bearing ring member (1-3) from the said backing plate 17, normally, each said bearing ring member ( 1 to 3) are demagnetized by applying reverse excitation to the bearing members (1 to 3). However, even if such an operation is performed, it is difficult to sufficiently reduce the residual magnetism of each of the track ring members (1 to 3).

  In view of such circumstances, conventionally, as described in Patent Document 1, the raceway members (1 to 3) removed from the backing plate 17 have been subjected to demagnetization treatment. ing. This demagnetization process is usually performed as shown in FIG. That is, a target race ring member (the hub 1 in the illustrated example) is placed on the conveyor 20 that continuously travels, and the alternating magnetic field generated above the demagnetizing yoke 21 has a constant speed in the horizontal direction. Pass through. At this time, the axial direction of the raceway ring member (1) and the vibration direction of the alternating magnetic field are set to be the same direction (vertical direction in the illustrated example). Thereby, the said magnetic ring member (1) is demagnetized by applying the said alternating magnetic field to the said ring member (1) to an axial direction with the said passage. The same applies to the case where the target ring member is the inner ring 2 or the outer ring 3.

  However, the residual magnetism of each of the bearing ring members (1 to 3) cannot be completely removed even by the demagnetization process as described above. That is, due to the influence of the size and shape of each of the raceway members (1 to 3), some degree of magnetism remains in each of the raceway members (1 to 3). Further, since the takt time (processing time / piece) of the demagnetizer shown in FIG. 6 is sufficiently shorter than the takt time of the grinding machine shown in FIG. 5, for example, in the actual production line, The porcelain machine is often shared by the raceway members (1 to 3). That is, the demagnetization treatment of each of the bearing ring members (1 to 3) is usually performed by the same demagnetizer for the hub 1 and the outer ring 3 having a large volume and the inner ring 2 having a small volume. Done on condition. For this reason, the residual magnetism after the demagnetization process is larger in the hub 1 and the outer ring 3 having a large volume than in the inner ring 2 having a small volume. In any case, the residual magnetism of the outer ring 3 out of the residual magnetism of each of the track ring members (1 to 3) enters and exits from the detection surface of the encoder 5 in the state of use, and the sensor 16 It is difficult to adversely affect the magnetic flux passing through the detection unit 24. This is because, in addition to the fact that the residual magnetism of the outer ring 3 is reduced to some extent by the demagnetization process described above, the outer ring 3 is not in direct contact with the encoder 5 and the sensor This is because it exists at a position relatively distant from the 16 detection units 24. On the other hand, the residual magnetism of the combined body of the hub 1 and the inner ring 2 is a magnetic flux that enters and exits the detection surface of the encoder 5 and passes through the detection unit 24 of the sensor 16 in use. Prone to adverse effects. The reason for this is that although the residual magnetism of the hub 1 and the inner ring 2 is reduced to some extent by the demagnetization process described above, the inner ring 2 is in direct contact with the encoder 5 and the This is because the sensor 16 exists at a position close to the detection unit 24. That is, in this state, the magnetic flux that exits (or enters this surface) in the axially inner end surface of the inner ring 2 easily flows on the detection unit 24 side of the sensor 16, and as a result, the detection unit 24 of the sensor 16. It is easy to adversely affect the magnetic flux passing through.

  Therefore, the magnetic flux passing through the detection unit 24 of the sensor 16 is hardly adversely affected, and the detection of the sensor 16 is performed from the surface of the inner end of the inner ring 2 in the axial direction so as to improve the reliability of rotation speed detection. It is desirable to realize a structure that can suppress the amount of magnetic flux that flows to the portion 24 side (or flows from the detection portion 24 side of the sensor 16 and enters the inner end surface of the inner ring 2 in the axial direction).

JP 2005-16569 A

  In view of the circumstances as described above, the present invention has an adverse effect on the magnetic flux that enters and exits the detection surface of the encoder and passes through the detection portion of the sensor even when a certain amount of magnetism remains in the shaft member and the inner ring. In order to make it difficult, the magnetic flux exits from the inner surface of the inner ring in the axial direction and flows to the sensor side of the sensor (or flows from the sensor side of the sensor and enters the inner surface of the inner ring in the axial direction). It was invented to realize a structure that can suppress the amount of the above.

Of the rolling bearing unit with an encoder according to the present invention and the manufacturing method thereof, the rolling bearing unit with an encoder according to claim 1 includes a rolling bearing unit and an encoder.
In particular, in the rolling bearing unit with an encoder according to claim 1, the polarity of the residual magnetism on the surface of one axial end portion of the shaft member having a relatively large volume, each of which constitutes the rolling bearing unit, The polarities of the remanent magnetism on the surface of one end in the axial direction of the inner ring having a small volume are made different from each other.

  When the rolling bearing unit with an encoder according to claim 1 is implemented, the rolling bearing unit may be, for example, one in which the inner ring is simply fitted and fixed to one axial end portion of the shaft member. Alternatively, as in the invention described in claim 2, by the caulking portion formed by plastically deforming one axial end portion of the shaft member on which the inner ring is fitted outwardly in the radial direction, The inner ring may be coupled and fixed to the shaft member while holding one end surface in the axial direction.

  According to a third aspect of the present invention, there is provided a method of manufacturing a rolling bearing unit with an encoder. Since the rolling bearing unit with an encoder as described above is manufactured, the polarity of residual magnetism on the surface of one axial end portion of the shaft member alone is obtained. And a process of making the polarities of the remanent magnetism on the surface of the one end portion in the axial direction in the state of the single inner ring different from each other. Thereafter, the shaft member and the inner ring are coupled to each other, and the encoder is assembled to the inner ring.

  Further, when the manufacturing method of the rolling bearing unit with an encoder described in claim 3 as described above is carried out, it is preferable that the target member is in a stationary state as in the invention described in claim 4. On the other hand, after applying an alternating magnetic field whose amplitude decreases with the passage of time in the axial direction, a process of stopping the application of the alternating magnetic field at a predetermined phase is performed for each of the shaft member and the inner ring. . Based on this, the polarity of the residual magnetism on the surface of the one end in the axial direction in the state of the single shaft member is made different from the polarity of the residual magnetism on the surface of the one end in the axial direction in the state of the single inner ring.

  According to the rolling bearing unit with an encoder of the present invention configured as described above, it flows out from the surface of one end of the inner ring in the axial direction and flows to the detection unit side of the sensor facing the detection surface of the encoder (or this The amount of magnetic flux that flows from the detection part side of the sensor and enters the surface of one end part in the axial direction of the inner ring can be suppressed. That is, in the case of the present invention, the polarity of the remanent magnetism on the surface of the one end portion in the axial direction of the inner ring is different from the polarity of the remanent magnetism on the surface of the one end portion in the axial direction of the shaft member. For this reason, the magnetic flux which comes out from the axial direction one end part surface of the said inner ring | wheel (or enters this surface) can be induced | guided | derived to the axial direction one end part surface side of the said shaft member. And by that amount, the inner ring exits from the surface of one end in the axial direction and flows to the detection unit side of the sensor facing the detection surface of the encoder (or the inner ring flows from the detection unit side of the sensor). The amount of magnetic flux (entering the surface of one end of the axis) can be suppressed (can be reduced or substantially zero). Accordingly, it is possible to reduce an adverse effect (an influence that changes the density and distribution) on the magnetic flux that enters and exits the detection surface of the encoder and passes through the detection unit of the sensor. As a result, it is possible to improve the reliability related to the measurement of the physical quantity such as the rotation speed, which is performed based on the detection of the magnetic flux entering and exiting the detection surface of the encoder by the detection unit of the sensor.

Moreover, according to the manufacturing method of the rolling bearing unit with an encoder of the present invention as described above, the rolling bearing unit with an encoder of the present invention as described above can be accurately manufactured.
In addition, when the manufacturing method of the present invention is carried out, if the configuration described in claim 4 is adopted, the polarity of the residual magnetism on the surface of the one end in the axial direction in the state of the shaft member alone, and the unit of the inner ring In this state, the operation of making the polarities of the remanent magnetism on the surface of the one end portion in the axial direction different from each other can be easily and accurately performed by stopping the application of the alternating magnetic field to the shaft member and the inner ring at a predetermined phase. In addition, since the work of applying an alternating magnetic field to the target member (the shaft member, the inner ring) is performed in a stationary state of the target member, the polarity of the residual magnetism on the surface of one end in the axial direction in the state of the target member alone Can be made equal over the entire circumference. That is, it is possible to prevent the polarity from being different in the circumferential direction.

Sectional drawing of the rolling bearing unit with an encoder regarding one example of embodiment of this invention. Similarly, the schematic diagram which shows the demagnetization process process of a bearing ring member. The figure which shows the measurement result of the experiment conducted in order to confirm the effect of this invention. Sectional drawing which shows an example of the rolling bearing unit with an encoder known conventionally. The fragmentary sectional view which shows the condition which grinds the surface of a bearing ring member. The schematic diagram which shows the demagnetization process process of the bearing ring member conventionally performed.

  One example of an embodiment of the present invention will be described with reference to FIGS. The feature of this example is that the polarities of the residual magnetism of the axially inner end surfaces of the hub 1 and the inner ring 2 constituting the rolling bearing unit with encoder are adjusted, or The point is to adjust. The structure, operation, and manufacturing method of the other parts are the same as those of the conventional structure shown in FIG. For this reason, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified. Hereinafter, the characteristic parts of this example will be mainly described.

As shown in FIG. 1, the rolling bearing unit with an encoder of this example has a residual magnetic polarity on the surface of the inner end portion in the axial direction of the hub 1 as the S pole, and a residual magnetism on the surface of the inner end portion in the axial direction of the inner ring 2. The polarity is N pole.
In order to manufacture a rolling bearing unit with an encoder having such a configuration, in the case of this example, in the manufacturing process of the hub 1 and the inner ring 2, after the above-described grinding process (see FIG. 5) is completed, After removing the hub 1 and the inner ring 2 from the backing plate 17 (see FIG. 5), the hub 1 and the inner ring 2 are each subjected to demagnetization processing as shown in FIG.

  That is, the target ring member (in the example shown, the hub 1) is placed on the transport conveyor 20a that travels intermittently, from the position (a) to the position (b) (above the demagnetizing yoke 21a). Move to the position of) and stop at that position. In this state, an AC voltage having a waveform as illustrated below (b) and whose amplitude decreases with the passage of time is applied to the coil 22 constituting the demagnetizing yoke 21a. As a result, an alternating magnetic field having a waveform similar to the AC voltage and having an amplitude that decreases with the passage of time is generated above the demagnetizing yoke 21a. And this alternating magnetic field is applied to an axial direction with respect to the said ring member (1). For this purpose, at the position (b), the vibration direction of the alternating magnetic field and the axial direction of the bearing ring member (1) are set in the same direction (vertical direction in the illustrated example). Then, by applying the alternating magnetic field to the bearing ring member (1) in the axial direction in this way, the residual magnetism of the bearing ring member (1) is reduced.

  Thereafter, the application of the alternating magnetic field to the ring member (1) (the application of the AC voltage to the coil 22) is stopped at a predetermined phase. Thus, the polarity of the remanent magnetism on the surface of the inner end portion in the axial direction of the bearing ring member (1) is changed to a desired polarity (in the example shown in the figure, since the bearing ring member is the hub 1, the S pole. Unlike this, if this race ring member is the inner ring 2, it is N pole.) In other words, the application of the alternating magnetic field is stopped at a phase where the polarity of the residual magnetism on the surface of the inner end portion in the axial direction of the ring member (1) becomes a desired polarity. After the application of the alternating magnetic field is stopped, the raceway member (1) is moved from the position (b) to the position (c) (the demagnetizing yoke 21a) by running the conveyor 20a by intermittent feeding. To a position deviated horizontally from above. At the same time, the next race ring member (1) is moved from the position (a) to the position (b), and the same demagnetization process is performed. In order to prevent the influence of the alternating magnetic field generated at the position (b) on the bearing ring member (1) after the demagnetization process moved to the position (c), the position (b) Measures such as sufficiently increasing the distance between the position (c) and the position (c), or providing a magnetic shielding plate 23 between the position (b) and the position (c). The same applies to the case where the target ring member is the inner ring 2.

Then, by combining the hub 1 and the inner ring 2 subjected to the demagnetization treatment as described above with other constituent members, the polarity of the residual magnetism on the axially inner end surface of the hub 1 becomes the S pole, The rolling bearing unit with an encoder of this example, which has a configuration in which the polarity of the remanent magnetism on the inner end surface in the axial direction of the inner ring 2 is N pole, is completed.
The volume ratio between the hub 1 and the inner ring 2 is often about 8 to 10: 1. In particular, in the case of a rolling bearing unit having a long distance between the ball rows, the ratio is about 20: 1. Sometimes it becomes. That is, it can be considered that the hub 1 and the inner ring 2 each having an axial residual magnetism are large and small magnets. In general, it is known that when large and small magnets are coupled, the overall magnetic polarity after the coupling follows a large magnet. However, in the relationship between the hub 1 and the inner ring 2, not all of the inner end surface in the axial direction of the inner ring 2 is covered by the caulking portion 12 of the hub 1. The caulking portion 12 is not in close contact with the entire surface. For this reason, among the inner end surfaces in the axial direction of the inner ring 2, in particular, the residual magnetism of the radially outer half (the vicinity of the shoulder portion of the inner ring 2 to which the encoder 5 is fitted and fixed) that is not covered by the caulking portion 12 The polarity does not necessarily follow the polarity of the remanent magnetism on the axially inner end surface of the hub 1. That is, as described above, if the hub 1 and the inner ring 2 after the demagnetization treatment are combined with other components to complete the rolling bearing unit with an encoder, the surface of the inner end portion in the axial direction of the hub 1 is obtained. Thus, a configuration can be realized in which the polarity of the residual magnetism becomes the S pole, and the polarity of the residual magnetism on the inner end surface in the axial direction of the inner ring 2 becomes the N pole.

  According to the rolling bearing unit with an encoder of this example and the manufacturing method thereof as described above, the magnetic flux generated from the axially inner end surface (N pole) of the inner ring 2 is closely opposed to the detected surface of the encoder 5. The amount flowing to the detection unit 24 side of the sensor 16 can be suppressed. That is, in the case of this example, the polarity of the residual magnetism (N pole) on the surface of one end in the axial direction of the inner ring 2 and the polarity of the residual magnetism (S pole) on the surface of one end in the axial direction of the hub 1 are They are different from each other. For this reason, the magnetic flux emitted from the axial end surface (N pole) of the inner ring 2 can be guided to the axial end surface (S pole) side of the hub 1. Accordingly, the amount of magnetic flux emitted from the surface (N pole) in the axial direction of the inner ring 2 can be reduced by that amount (reduced or substantially reduced to zero). Accordingly, it is possible to reduce adverse effects (such as changes in density and distribution) on the magnetic flux that enters and exits the detection surface of the encoder 5 and passes through the detection unit 24 of the sensor 16. As a result, it is possible to improve the reliability related to the measurement of the rotational speed, which is performed based on the detection of the magnetic flux entering and exiting from the detection surface of the encoder 5 by the sensor 16.

  In the case of this example, not only the magnetic flux generated from the detected surface of the encoder 5 and passing through the detection unit 24 of the sensor 16, but also the magnetic flux generated around by the residual magnetism of the inner ring 2, Magnetic flux generated around the hub 1 due to the residual magnetism also causes adverse effects. That is, as described above, the volume difference between the hub 1 and the inner ring 2 is considerably large, expressed as a ratio of about 8 to 20: 1. For this reason, if the demagnetization process described above is performed under the same conditions, the residual magnetism after the demagnetization process is considerably larger in the hub 1 having a larger volume than in the inner ring 2 having a smaller volume. Accordingly, in this case, almost all of the magnetic flux emitted from the surface (N pole) in the axial direction of the inner ring 2 is guided to the surface (S pole) side of the hub 1 in the axial direction. . And the quantity of the magnetic flux which goes out from the axial direction one end surface (N pole) of the said inner ring | wheel 2 and flows into the detection part 24 side of the said sensor 16 becomes substantially zero. However, also in this case, a part of the magnetic flux entering the surface of the inner end portion in the axial direction of the hub 1 flows from the detection unit 24 side of the sensor 16. Therefore, it is preferable to reduce the magnetic flux flowing from the detection unit 24 side of the sensor 16 from the viewpoint of sufficiently improving the reliability related to the measurement of the rotational speed. In other words, when the present embodiment is carried out, the hub 1 is designed so that the density of magnetic flux generated around the residual magnetism between the hub 1 and the inner ring 2 is as low as possible at the detection unit 24 of the sensor 16. It is preferable to adjust the magnitude of the residual magnetism after the demagnetization treatment with the inner ring 2. For this purpose, for example, when performing demagnetization processing between the hub 1 and the inner ring 2, the amplitude value immediately before the application of the alternating magnetic field is sufficiently reduced, or the amplitude immediately before the application of the alternating magnetic field is stopped. It is preferable to make the value smaller than the inner ring 2 with the hub 1 (in other words, larger with the inner ring 2 than the hub 1).

  In the case of this example, the polarity of the residual magnetism on the axial inner end surface of the hub 1 alone and the polarity of the residual magnetism of the axial inner end surface of the inner ring 2 alone The operation of making the two different from each other can be performed easily and accurately by stopping the application of the alternating magnetic field to the hub 1 and the inner ring 2 (application of the alternating voltage to the coil 22) at a predetermined phase. In addition, since the work of applying an alternating magnetic field to the target member (the hub 1 and the inner ring 2) is performed in a stationary state of the target member, the residual magnetism on the surface in the axial direction at the end of the target member alone. Can be made the same polarity over the entire circumference. That is, it is possible to prevent the polarity from being different in the circumferential direction.

  An experiment conducted for confirming the effect of the present invention will be described. The experiment was conducted on eight types of samples (Examples 1 to 4 and Comparative Examples 1 to 4). Each of these samples is a combined body in which the hub 1 and the inner ring 2 are connected to each other as shown in FIGS. In addition, Examples 1 to 4 of these are samples having the characteristics of the present invention, and the polarities of the remanent magnetism on the axially inner end surfaces of the hub 1 and the inner ring 2 are different from each other. . On the other hand, Comparative Examples 1 to 4 are samples that do not have the characteristics of the present invention, and the polarities of the residual magnetisms on the axially inner end surfaces of the hub 1 and the inner ring 2 are the same. . Further, both the example and the comparative example have different sample numbers, and the absolute values of the residual magnetism of the race ring members (the hub 1 and the inner ring 2) are different, but the sample numbers are common. Regarding the thing, the absolute value of the remanent magnetism of the bearing ring member (the hub 1 and the inner ring 2) is almost equal between the example and the comparative example.

  For each sample as described above, the magnetic flux density at the inner end surface in the axial direction of the hub 1 and the index of the residual magnetism of the inner ring 2 are used as an index of the residual magnetism of the hub 1. The magnetic flux density on the inner end surface in the axial direction and the position where the detector 24 of the sensor 16 (see FIG. 4) is disposed {the encoder 5 disposed in the same virtual plane as the inner end surface in the axial direction of the inner ring 2 (see FIG. 4) The magnetic flux density at the detection position, which is a position 3 mm away from the center in the radial direction of the surface to be detected in the axial direction, was measured. The measurement results are shown in FIG.

  Among the measurement results shown in FIG. 3, the bearing ring members (the hub 1 and the inner ring 2) after the demagnetization treatment are understood as compared with the measurement results of the example and the comparative example having the same numbers. When the magnitudes of the residual magnetism are equal, the magnetic flux density at the detection position is sufficiently smaller in the example than in the comparative example. For this reason, according to the present invention, the reliability related to the measurement of physical quantities such as the rotational speed, which is performed based on the detection of the magnetic flux entering and exiting the detection surface of the encoder 5 by the detection unit 24 of the sensor 16. You can see improvement. In order to suppress the measurement error of the physical quantity, it is preferable to suppress the magnetic flux density at the detection position to be equal to or lower than the detection threshold (threshold) of the sensor 16. For example, when this threshold is 0.1 mT, according to the measurement result of FIG. 3, with respect to the structure of the comparative example, the bearing ring members (the hub 1 and the inner ring 2) are compared with those of the comparative examples 2 and 3. Although it is necessary to lower the residual magnetism, it is only necessary to lower the residual magnetism of the bearing ring member (the hub 1 and the inner ring 2) to the extent of the first embodiment with respect to the structure of the embodiment. Therefore, according to the present invention, it is easy to suppress the magnetic flux density at the detection position.

DESCRIPTION OF SYMBOLS 1 Hub 2 Inner ring 3 Outer ring 4 Rolling element 5 Encoder 6 Rotation side flange 7a, 7b Inner ring raceway 8 Small diameter step part 9 Static side flange 10a, 10b Outer ring raceway 11 Cylindrical part 12 Caulking part 13 Core metal 14 Encoder main body 15 Cover 16 Sensor 17 Backing plate 18 Shoe 19 Grinding stone 20, 20a Conveyor 21, 21a Demagnetizing yoke 22 Coil 23 Magnetic shielding plate 24 Detector

Claims (4)

A rolling bearing unit and an encoder;
Of these, the rolling bearing unit includes a shaft member and an inner ring having a volume smaller than that of the shaft member, and the inner ring is externally fitted and fixed to one axial end portion of the shaft member.
The encoder includes an annular multipolar magnet in which S poles and N poles are alternately arranged with respect to the circumferential direction, and the axial direction of the inner ring in a state where the multipolar magnet is arranged concentrically with the inner ring. In a rolling bearing unit with an encoder supported and fixed at one end,
A rolling bearing unit with an encoder, wherein the polarity of residual magnetism on one axial end surface of the shaft member is different from the polarity of residual magnetism on the axial end surface of the inner ring.   The rolling bearing unit has a portion protruding from one end surface in the axial direction of the inner ring, out of the cylindrical portion provided at one end portion in the axial direction of the shaft member, while the outer ring is fitted on a portion near the one end in the axial direction of the shaft member. 2. The inner ring is coupled and fixed to the shaft member by restraining one end surface in the axial direction of the inner ring by a caulking portion formed by plastic deformation of the outer ring in a radially outward direction. Rolling bearing unit with encoder described in 1.   In order to manufacture the rolling bearing unit with an encoder according to any one of claims 1 and 2, the polarity of the residual magnetism on the surface of one end in the axial direction in the state of the shaft member alone, and the unit of the inner ring alone A rolling bearing unit with an encoder in which the shaft member and the inner ring are coupled to each other, and the encoder is assembled to the inner ring after the process of making the residual magnetism polarities of the one end surface in the axial direction different from each other. Manufacturing method.   In a stationary state of the target member, after applying an alternating magnetic field whose amplitude decreases with time to the target member in the axial direction, a process of stopping the application of the alternating magnetic field at a predetermined phase is performed with the shaft member. Based on the implementation with respect to each of the inner rings, the polarity of the residual magnetism on the surface of the one end in the axial direction in the state of the shaft member alone, and the residual on the surface of the one end in the axial direction in the state of the inner ring alone. The method for manufacturing a rolling bearing unit with an encoder according to claim 3, wherein the magnetic polarities are different from each other.

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