JP2004218841A - Rolling bearing unit with rotational speed detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent muddy water or the like from entering an outer ring 8 or synthetic resin cover 18b with one O-ring 37. <P>SOLUTION: A third micro clearance exists between the inner end surface of the outer ring 8 and the external side surface of the cover 18b. A first micro clearance exists between the inner-periphery surface of the inner edge of the outer ring 8 and the outer-periphery surface of a metal sleeve 31. A second micro clearance exists between the sleeve 31 and synthetic resin constituting the cover 18b. The muddy water or the like which invades from the third micro computer is shut off by the O-ring 37. The muddy water can be prevented from entering the outer ring 8 and the synthetic resin cover 18b through the first and the second micro clearances. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  A rolling bearing unit with a rotation speed detecting device according to the present invention is used for rotatably supporting a wheel of an automobile on a suspension device and detecting a rotation speed of the wheel.

  A rotational speed detector for rotatably supporting the wheels of the vehicle with respect to a suspension device and detecting the rotational speed of the wheels to control an antilock brake system (ABS) or a traction control system (TCS). 2. Description of the Related Art Various types of rolling bearing units have been known as device-equipped rolling bearing units. Each of the rotation speed detection devices incorporated in such a rolling bearing unit with a rotation speed detection device includes a tone wheel that rotates together with a wheel, and a sensor that outputs an output signal that changes at a frequency proportional to the rotation speed of the tone wheel. Prepare. For example, Non-Patent Document 1 describes a rolling bearing unit with a rotation speed detecting device as shown in FIGS.

  An outer end portion of the hub 1 which is a member corresponding to an inner ring (the outside is a side which is outside in the width direction of the vehicle when assembled to the vehicle, and a left side in each drawing) A flange portion for fixing wheels is provided on an outer peripheral surface. 2, and an inner raceway 3a and a step 4 are formed on the outer peripheral surface of the intermediate portion. On the outer peripheral surface of the hub 1, an inner raceway 3b is formed on the outer peripheral surface, and the inner race 5 constituting an inner race equivalent member together with the hub 1 is brought into contact with the outer end surface against the step portion 4. External fitting is supported. The inner raceway 3a is formed on an inner race (not shown) separate from the hub 1 instead of being formed directly on the outer peripheral surface of the hub 1, and the inner race and the inner race 5 are separated from the hub 1 by the outer race. In some cases, they are fitted and fixed.

  A male screw portion 6 is formed in a portion near the inner end of the hub 1. The inner ring 5 is fixed to a predetermined portion of the outer peripheral surface of the hub 1 by a nut 7 which is screwed into the male screw portion 6 and further tightened to form a member equivalent to the inner ring. A mounting portion 9 for fixing the outer ring 8 to a suspension device is provided on an outer peripheral surface of an intermediate portion of the outer ring 8 arranged around the hub 1. In addition, outer ring raceways 10a and 10b are formed on the inner peripheral surface of the outer race 8 so as to face the inner ring raceways 3a and 3b, respectively. A plurality of rolling elements 11, 11 are provided between the inner raceways 3a, 3b and the outer raceways 10a, 10b, respectively, so that the hub 1 can rotate freely inside the outer race 8. Although balls are used as the rolling elements 11 in the illustrated example, tapered rollers may be used as rolling elements in the case of a heavy-duty rolling bearing unit for an automobile. A seal ring 12 is attached between the inner peripheral surface of the outer end of the outer race 8 and the outer peripheral surface of the hub 1 so that the seal ring 12 is provided between the inner peripheral surface of the outer race 8 and the outer peripheral surface of the hub 1. The outer end opening of the space in which the plurality of rolling elements 11 and 11 are provided is closed.

  At the inner end of the inner ring 5 (the inside is the side closer to the center in the width direction of the vehicle when assembled to the vehicle, and at the right side of each drawing), a portion deviating from the inner ring raceway 3b includes a tone wheel 13b. The base end (the left end in FIGS. 6 and 7) is externally fitted and fixed. The entire tone wheel 13 is formed in an annular shape (short cylindrical shape) from a magnetic metal plate such as a steel plate. The tone wheel 13 includes a small-diameter portion 14 and a large-diameter portion 15 formed concentrically with each other by a step 16. In such a tone wheel 13, the large-diameter portion 15 is fitted on the outer peripheral surface of the end of the inner ring 5, and the step 16 is brought into contact with the edge of the inner ring 5. The support is fixed. Therefore, the small diameter portion 14 is supported concentrically with the inner ring 5. Then, a plurality of through-holes 17, which are rotation-side thinned portions, are formed in the small-diameter portion 14 at equal intervals in the circumferential direction, and the magnetic properties in the circumferential direction are alternately and uniformly changed. ing. Each of the through holes 17 has the same shape and is a rectangle that is long in the axial direction (the left and right direction in FIGS. 6 and 7).

  The opening at the inner end of the outer ring 8 is covered with a cover 18 made into a bottomed cylindrical shape by drawing a metal plate such as a stainless steel plate or an aluminum alloy plate. An annular synthetic resin 21 in which an annular sensor 20 is embedded is held and fixed on the inner peripheral side of the cylindrical portion 19 constituting the cover 18. The sensor 20 includes a permanent magnet 22, a stator 23 made of a magnetic material such as a steel plate, and a coil 24. These members 22, 23, and 24 are embedded in the synthetic resin 21. Thus, the entire structure is annular.

  The permanent magnet 22 of the constituent members of the sensor 20 is formed in an annular shape (ring shape) as a whole, and is magnetized in the diameter direction. The inner peripheral surface of the permanent magnet 22 is opposed to the outer peripheral surface of the portion where the through hole 17 is not formed at the base end portion of the small diameter portion 14 constituting the tone wheel 13 via the minute gap 25. Let me. The stator 23 has a substantially J-shaped cross section and is formed in an annular shape as a whole. The inner peripheral surface of the end portion of the outer cylindrical portion 26 constituting the stator 23 and the outer peripheral surface of the permanent magnet 22 are brought close to or in contact with each other. Further, the inner peripheral surface of the inner diameter side cylindrical portion 27 constituting the stator 23 is opposed to a portion of the tone wheel 13 where the plurality of through holes 17 are formed. Further, a plurality of notches 28, which are fixed-side thinned portions, are formed in the inner diameter side cylindrical portion 27 at equal pitches (center angle) with the through holes 17 in the circumferential direction of the inner diameter side cylindrical portion 27. Pitch). Therefore, the inner diameter side cylindrical portion 27 is formed in a comb shape.

  Further, the coil 24 is formed in an annular shape by winding a conductive wire around a bobbin 29 made of a non-magnetic material, and is disposed on an inner peripheral side portion of an outer diameter side cylindrical portion 26 constituting the stator 23. . The electromotive force generated by the coil 24 is extracted from a connector 30 projecting from the outer surface of the cover 18.

  When the tone wheel 13 rotates together with the hub 1 when using the rolling bearing unit with the rotation speed detecting device configured as described above, the magnetic flux density in the stator 23 facing the tone wheel 13 changes, and the coil 24 The induced voltage changes at a frequency proportional to the rotation speed of the hub 1. The principle that the voltage induced in the coil 24 changes in response to the change in the density of the magnetic flux flowing through the stator 23 is the same as that of a conventionally widely known rotational speed detecting sensor. The reason why the density of the magnetic flux flowing through the stator 23 changes in accordance with the rotation of the tone wheel 13 is as follows.

  Since the plurality of through holes 17 provided in the tone wheel 13 and the notch 28 provided in the stator 23 have the same pitch, there is a moment when they face each other simultaneously over the entire circumference as the tone wheel 13 rotates. . At the moment when each of the through holes 17 and each of the notches 28 oppose each other, the pillar portion which is a magnetic material existing between the adjacent through holes 17 and the between the notches 28 also adjacent to each other. The existing magnetic tongue pieces oppose each other via the minute gap 25. In the state where the pillar portions and the tongue pieces, each of which is a magnetic material, face each other, a high-density magnetic flux flows between the tone wheel 13 and the stator 23.

  On the other hand, if the phase between the through hole 17 and the notch 28 is shifted by half, the density of the magnetic flux flowing between the tone wheel 13 and the stator 23 becomes low. That is, in this state, the through hole 17 provided in the tone wheel 13 faces the tongue piece, and the notch 28 provided in the stator 23 faces the pillar portion at the same time. In the state where the pillar portion faces the notch 28 and the tongue piece faces the through hole 17, a relatively large gap exists between the tone wheel 13 and the stator 23 over the entire circumference. . In this state, the density of the magnetic flux flowing between the two members 13 and 23 becomes low. As a result, the voltage induced in the coil 24 changes in proportion to the rotation speed of the hub 1. By operating as described above, the sensor 20 changes the output voltage induced in the coil 24 at a frequency proportional to the rotation speed of the hub 1.

  Further, Patent Document 1 discloses a structure in which a cover 18a for closing an inner end opening of an outer ring 8 is made of synthetic resin and a sensor 20a is embedded in the synthetic resin constituting the cover 18a, as shown in FIG. Has been described. On the outer peripheral surface of the opening end of the cover 18a, a sleeve 31 having an L-shaped cross section and formed entirely in an annular shape is fixed by a metal plate having sufficient rigidity such as a steel plate. The sleeve 31 is set in the cavity when the cover 18a is injection-molded, so that the sleeve 31 is molded in the synthetic resin.

  The cover 18 a as described above is fixed to the outer ring 8 by fitting the sleeve 31 into the inner end opening of the outer ring 8. In the case of such a structure incorporating the cover 18a made of a synthetic resin, the number of components can be reduced as compared with the structure shown in FIGS. 6 and 7 above, and the cost of the rolling bearing unit with the rotation speed detecting device is reduced. Reduction can be achieved.

  However, even in the case of a rolling bearing unit with a rotation speed detecting device as shown in FIG. 8, there are still points to be solved as described below. That is, muddy water is applied to the cover 18a and the outer ring 8 during running on rainy weather and the like, and washing water is urged from a high-pressure car washer during car washing. When such muddy water or washing water (hereinafter referred to as “muddy water”) leaks into the cover 18a and the outer ring 8, not only does the durability of the rolling bearing unit be impaired, but also the reliability of the rotation speed detecting unit is reduced. May have adverse effects.

For example, in the case of the conventional structure shown in FIG. 8, muddy water or the like leaks into the inside of the cover 18a and the outer ring 8 through the following two routes (1) and (2).
(1) A first minute gap existing in a fitting surface portion between the outer peripheral surface of the sleeve 31 and the inner peripheral surface of the inner end portion of the outer ring 8.
(2) A second minute gap existing at a contact portion between the inner peripheral surface of the sleeve 31 and the outer peripheral surface of the synthetic resin forming the cover 18a.
The first minute gap is formed due to minute irregularities inevitably existing on the outer peripheral surface of the sleeve 31. That is, it is inevitable that minute irregularities of about several tens of μm exist on the surface of the sleeve 31 made of a metal plate such as a stainless steel plate. For this reason, even if the sleeve 31 is fitted and fixed to the inner end opening of the outer ring 8 with an interference fit, the first minute gap is formed, and the leakage of the muddy water or the like through the first minute gap. Can occur.
The second minute gap is formed due to a difference in the coefficient of thermal expansion between the metal forming the sleeve 31 and the synthetic resin forming the cover 18a. And there is a possibility that leakage of the muddy water or the like may occur even through such a second minute gap.

European Patent Publication EP 0 557 931 A1 Invention Association Open Technical Report 94-16051

  In view of such circumstances, the rolling bearing unit with the rotation speed detecting device of the present invention prevents leakage of muddy water or the like into the cover 18a and the outer ring 8 through the first and second gaps. It was invented to prevent this with a seal ring.

  The rolling bearing unit with the rotation speed detecting device of the present invention has an outer ring raceway on the inner peripheral surface similarly to the rolling bearing unit with the rotation speed detecting device of the second conventional example shown in FIG. An outer ring that does not rotate, an inner ring raceway on the outer peripheral surface facing the inner peripheral surface, a member corresponding to an inner race that rotates during use, and a plurality of rolling elements rotatably provided between the outer raceway and the inner raceway. A moving body, an annular tone wheel fixed to the inner ring-equivalent member and alternately and equally spaced in a circumferential direction, and a synthetic resin cover fixed to an inner end opening of the outer ring. An annular sensor facing the tone wheel in a state of being embedded in a synthetic resin constituting the cover, and a metal cylindrical sleeve fixed to a peripheral surface of an opening of the cover. . The cover is fixed to the outer ring by fitting one peripheral surface of the sleeve to an end peripheral surface of the outer ring.

  The minute gap existing at the fitting surface between the sleeve and the outer ring is defined as a first minute gap, and the minute gap existing at the contact portion between the sleeve and the synthetic resin forming the cover is defined as a second minute gap. When the minute gap existing between the outer ring and the cover is defined as a third minute gap, the first minute gap and the third minute gap arranged in series with each other cause a first leak. A flow path is formed, and the second minute gap and the third minute gap arranged in series with each other constitute a second leakage path.

  In particular, in the rolling bearing unit with the rotation speed detecting device of the present invention, one seal ring is provided between the cover and the outer ring with respect to any of the first and second leak passages. It is provided in the part located in series. In this manner, one seal ring (general term for ring-shaped sealing materials such as an O-ring and a flat packing formed in a ring shape) is connected in series to both the first and second leakage channels. For example, the synthetic resin is exposed on the end face of the cover without covering the end face with a sleeve, and a seal ring is provided between the end face and the end face of the outer ring.

The rolling bearing unit with the rotation speed detection device of the present invention configured as described above rotatably supports the wheel on the suspension device, or the operation itself when detecting the rotation speed of the wheel is as described above. This is the same as the case of the conventional structure. In particular, in the case of the rolling bearing unit with the rotation speed detecting device of the present invention, since one seal ring can prevent foreign substances such as muddy water from entering the cover, a highly reliable structure can be realized at low cost. .
As described above, the present invention can provide a rotation speed detecting device that can be configured at a low cost with a small number of components and that has excellent durability and reliability.

  1 and 2 show a first embodiment of the present invention. The feature of the rolling bearing unit with a rotation speed detecting device of the present invention is that a cover 18b that supports a sensor 20b that forms the rotation speed detecting device and a seal structure of a fitting portion between the outer ring 8 that forms the rolling bearing unit. is there. The structure of the rolling bearing unit is the same as that of the first example of the conventional structure shown in FIG. For this reason, with regard to the rolling bearing unit portion, the same reference numerals are given to the same portions, and the overlapping description is omitted or simplified, and the following description will focus on the characteristic portions of the present invention.

  A cover 18b made of synthetic resin is attached to the inner end opening of the outer ring 8 to close the inner end opening of the outer ring 8. The inner end of the sensor 20b is embedded in the outer surface of the cover 18b. The outer half of the sensor 20b, which is formed in an annular shape, projects outward from the outer surface of the cover 18b. On the inner surface of the cover 18b, a connector 30 for extracting a detection signal of the sensor 20b is formed integrally with the cover 18b. An outwardly protruding convex portion 32 is formed over the entire outer periphery of the outer surface of the cover 18b at a position slightly inward in the diameter direction from the outer peripheral edge. The inner end of the sensor 20b is embedded in the center of the projection 32 in the diameter direction.

  A sleeve 31 is provided along the outer peripheral surface of the convex portion 32. The sleeve 31 is formed by forming a metal plate such as a stainless steel plate into an annular shape with an L-shaped cross section, and is bent outward from the inner end edge of the cylindrical portion 33 in the diametric direction. A flange-shaped flange portion 34. The cylindrical portion 33 is disposed along the outer peripheral surface of the convex portion 32, and further projects outward from a leading edge (outer edge) of the convex portion 32. On the other hand, the flange portion 34 is embedded at the center in the thickness direction of a portion that is located diametrically outward of the convex portion 32 at the outer peripheral edge of the cover 18b. Note that the outer peripheral edge of the flange portion 34 does not reach the outer peripheral edge of the cover 18b, but is embedded inside the cover 18b.

  A chamfered portion 35 is formed on the inner peripheral edge of the inner end opening of the outer ring 8 for fitting and fixing the cover 18b provided with the sleeve 31 as described above. When closing the inner end opening of the outer ring 8 with the cover 18b, the sleeve 31 is fitted inside the inner end of the outer ring 8, and the outer surface of the cover 18b is brought into contact with the outer peripheral portion. In this state, a space 36 having a triangular cross-sectional shape and a whole annular shape surrounded by the outer peripheral surface of the cover 18b, the outer peripheral surface of the intermediate portion of the cylindrical portion 33, and the chamfered portion 35 is formed. It is formed. In the case of the rolling bearing unit with the rotation speed detecting device of the present invention, an O-ring 37 which is a kind of a seal ring is mounted in the space 36 in a state of being elastically compressed.

  Since the O-ring 37 is provided in the space 36 provided at the above-mentioned position in an elastically compressed state, it is possible to reliably prevent muddy water or the like from leaking into the cover 18b and the outer ring 8. That is, muddy water and the like existing around the cover 18b and the outer ring 8 pass through the third minute gap existing between the inner end surface of the outer ring 8 and the outer peripheral portion of the outer surface of the cover 18b, and the solid line in FIG. As shown by an arrow A, the space 36 enters a portion near the outer periphery of the space 36. However, the muddy water or the like that has entered the outer peripheral portion of the space 36 in this way is blocked by the O-ring 37 and does not enter the inner peripheral portion of the space 36. On the other hand, one end of the first minute gap existing on the fitting surface between the outer peripheral surface of the sleeve 31 and the inner peripheral surface of the inner end portion of the outer ring 8, and contact between the sleeve 31 and the synthetic resin forming the cover 18b. Any one end of the second minute gap existing in the portion communicates with the portion of the space 36 near the inner periphery. Therefore, muddy water or the like that has entered the outer peripheral portion of the space 36 from the third minute gap does not enter the first and second minute gaps.

  In other words, the O-ring 37 also allows the second minute gap and the third minute gap to be in contact with the first leak passage formed by the first minute gap and the third minute gap. The O-ring 37 is provided at a portion located in series with respect to the second leakage flow path to be configured, so that one O-ring 37 can prevent muddy water or the like from entering the outer ring 8 and the cover 18b. That is, the muddy water and the like do not flow through the first and second leak passages as indicated by broken arrows B and C in FIG.

  In the illustrated embodiment, the relative speed between the opposing surfaces of the sensor 20b and the tone wheel 13a is increased, and the magnetic resistance between these two members 20b and 13a is simultaneously changed at two locations. Accordingly, the output change of the sensor 20b is increased. The sensor 20b includes an annular permanent magnet 22a magnetized in the axial direction (the left-right direction in FIGS. 1 and 2). The base end of the first stator 38 is brought into contact with the axially outer end surface (the left end surface in FIGS. 1 and 2) of the permanent magnet 22a. The large-diameter portion 15a that constitutes 13a is opposed to the inner peripheral surface of the middle portion via a minute gap. Further, the base end of the second stator 39 is brought into contact with the inner end face in the axial direction (the right end face in FIGS. 1 and 2) of the permanent magnet 22a. The inner peripheral surface of the inner end of the radial portion 15a in the axial direction is also opposed to the inner peripheral surface via a minute gap.

  By forming notches 40, 40 in the inner half of the large diameter portion 15a, the notches 28, 28 are formed in the tip portions of the first stator 38 and the second stator 39, respectively. Each part is formed in a comb shape. Of course, the pitches of these notches 40, 28 are equal to each other. The notches 28 formed in the first and second stators 38 and 39 have the same phase. For this purpose, through holes 41, 41 formed in the first and second stators 38, 39, and convex portions 42, 42 formed in a bobbin 29a for winding a conductor constituting a coil 24a described below. And are engaged. A coil 24a is provided in a portion surrounded by the permanent magnet 22a, the first stator 38, and the second stator 39. The change in the density of the magnetic flux flowing through each of the members 22a, 38, and 39 causes a voltage that changes at a frequency proportional to the rotation speed of the tone wheel 13a.

  With the above-described configuration, the resistance to the flow of the magnetic flux accompanying the rotation of the tone wheel 13a is reduced not only in the opposing portion between the leading end of the first stator 38 and the large-diameter portion 15a, but also in the second stator. It also changes simultaneously at the portion where the leading end of 39 and the large diameter portion 15a face each other. Accordingly, the change in the magnetic flux density due to the rotation of the tone wheel 13a increases, and the output of the sensor 20b can be increased. Further, in the illustrated embodiment, the sensor 20b is disposed on the inner diameter side of the large diameter portion 15a constituting the tone wheel 13a, and the inner peripheral surface of the large diameter portion 15a and the outer peripheral surface of the sensor 20b face each other. The relative speed between these two peripheral surfaces is higher than in the case of the above-described conventional structure. As described above, the output of the sensor 20b is also increased by increasing the relative speed between the two peripheral surfaces. The structure of such a rotational speed detecting device is not the gist of the present invention. In practicing the present invention, various structures can be adopted as the structure itself of the rotation speed detecting device, including the conventional structure shown in FIGS.

  4 and 5 show a second embodiment of the present invention. In the case of this embodiment, the flange portion 34 of the sleeve 31 is embedded in the outer surface of the cover 18b near the outer periphery so as to be flush with the outer surface. A locking groove 43 is formed over the entire circumference at a portion closer to the outer periphery of the outer surface of the cover 18b and further closer to the outer periphery than the flange portion 34. The O-ring 37 locked in the locking groove 43 elastically contacts the inner end surface of the outer ring 8. Also in the case of the present embodiment, the O-ring 37 dams muddy water or the like that has entered the third minute gap as shown by the solid line arrow A in FIG. Therefore, it is possible to prevent the muddy water and the like from flowing through the first and second minute gap portions as shown by the broken arrows B and C in FIG.

FIG. 1 is a cross-sectional view illustrating a first embodiment of the present invention. FIG. 2 is an enlarged view of the right part of FIG. 1. The enlarged view of the A section of FIG. FIG. 3 is a view similar to FIG. 2, but showing a second embodiment of the present invention. The enlarged view of the B section of FIG. Sectional drawing which shows the 1st example of a conventional structure. FIG. 7 is an enlarged view of the right part of FIG. 6. FIG. 6 is a partial cross-sectional view showing a second example of the conventional structure.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Hub 2 Flange part 3a, 3b Inner ring raceway 4 step part 5 Inner ring 6 Male thread part 7 Nut 8 Outer ring 9 Attachment part 10a, 10b Outer ring raceway 11 Rolling element 12 Seal ring 13, 13a Tone wheel 14 Small diameter part 15, 15a Large diameter part 16 Step portion 17 Through hole 18, 18a, 18b Cover 19 Cylindrical portion 20, 20a, 20b Sensor 21 Synthetic resin 22, 22a Permanent magnet 23 Stator 24, 24a Coil 25 Micro gap 26 Outer diameter side cylindrical portion 27 Inner diameter side cylindrical portion 28 Notch 29, 29a Bobbin 30 Connector 31 Sleeve 32 Convex part 33 Cylindrical part 34 Flange part 35 Chamfer part 36 Space 37 O-ring 38 First stator 39 Second stator 40 Notch 41 Through hole 42 Convex part 43 Locking concave groove

Claims (1)

  An outer ring that has an outer raceway on the inner peripheral surface and does not rotate during use, an inner raceway member that has an inner raceway on the outer peripheral surface facing the inner peripheral surface and rotates during use, and the outer raceway and the inner raceway A plurality of rolling elements provided rotatably between them, an annular tone wheel fixed to the inner ring-equivalent member and alternately and equally spaced in a circumferential direction, and an inner ring of the outer ring. A cover made of synthetic resin fixed to the end opening, an annular sensor facing the tone wheel in a state of being embedded in the synthetic resin constituting the cover, and fixed to the opening peripheral surface of the cover The cover is fixed to the outer ring by fitting one peripheral surface of the sleeve to an end peripheral surface of the outer ring, and the cover is fixed to the outer ring. Minute gaps on the mating surface with the outer ring A first minute gap, a minute gap existing at a contact portion between the sleeve and the synthetic resin forming the cover is defined as a second minute gap, and a minute gap existing between the outer ring and the cover is defined as a third minute gap. In the case of the minute gap, the first minute gap and the third minute gap arranged in series with each other constitute a first leakage flow path, and the second minute gap arranged in series with each other In a rolling bearing unit with a rotation speed detecting device, wherein a third minute gap forms a second leak passage, between the cover and the outer ring, and the first and second leak passages A rolling bearing unit with a rotation speed detecting device, wherein one sealing ring is provided in a portion located in series with any one of the above.

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