Wheel bearing apparatus incorporated with a wheel speed detecting apparatus

A wheel bearing apparatus has a wheel speed detecting apparatus which can prevent ingress of foreign matter into the wheel speed detecting portion of the wheel bearing apparatus. The wheel bearing apparatus has an encoder (19) mounted on the outer circumferential surface of an inner ring (6). A sensor holder (15) is arranged on the end of the outer member (4) opposite to the encoder (19). The sensor holder (15) includes an annular fitting member (16) and a holding portion (17). The holding portion (17) is formed by synthetic resin molded integrally with the annular fitting member (16). A wheel speed detecting sensor (20) is embedded in the resin and is positioned opposite to the encoder (19), via a predetermined gap between the two. A seal (11) is arranged at the inboard side of the encoder (19). The seal (11) includes a first sealing plate (21) and a second sealing plate (22) fit, respectively, on the sensor holder (15) and the inner ring (6). The tip end (26) of the annular fitting member (16) is enveloped by plastic resin that forms the holding portion (17).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2005-081813, filed Mar. 22, 2005, which application is herein expressly incorporated by reference.

FIELD

The present disclosure relates to a vehicle wheel bearing apparatus and, more particularly, to a wheel bearing apparatus which incorporates a wheel speed detecting apparatus to detect rotational speed of the vehicle wheel.

BACKGROUND

Wheel bearing apparatus is generally known which supports a vehicle wheel relative to a suspension apparatus and which incorporates a wheel speed detecting apparatus to detect rotational speed of the vehicle wheel. The detecting apparatus detects the wheel speed to control the anti-lock braking system (ABS). Such a bearing apparatus generally includes a wheel speed detecting apparatus with a magnetic encoder. The encoder has magnetic poles alternately arranged along its circumferential direction. The magnets are integrated in a sealing apparatus arranged between inner and outer members to contain rolling elements (balls or rollers). A wheel speed detecting sensor detects the variation in the magnetic poles of the magnetic encoder according to the rotation of the wheel.

The wheel speed sensor is usually mounted on a knuckle after the wheel bearing apparatus has been mounted on the knuckle to form a suspension apparatus. Wheel bearing apparatus with a wheel speed detecting apparatus have recently been proposed where a wheel speed detecting sensor is self-contained within the wheel bearing. This reduces the size of the wheel bearing apparatus as well as eliminates troublesome in air gap adjustment between the wheel speed sensor and the magnetic encoder.

An example of a wheel bearing apparatus with a wheel speed detecting apparatus known in the prior art (e.g. Japanese Laid-open Patent Publication No. 2003-254985) is shown inFIG. 5. This wheel bearing apparatus with a wheel speed detecting apparatus includes an outer member51which forms a stationary member secured on a suspension apparatus (not shown). An inner member52, which includes a wheel hub55and an inner ring56, is inserted into the outer member51via double row rolling elements (balls)53and53therebetween. The outer member51has an integrally formed wheel mounting flange at one end and double row outer raceway surfaces51aand51aformed on its inner circumferential surface. The inner member52has double row inner raceway surfaces55aand56aopposite to the double row outer raceway surfaces51aand51a. One (55a) of the double row inner raceway surfaces is formed on the outer circumferential surface of the wheel hub55. The other (56a) is formed on the outer circumferential surface of the inner ring6. The inner ring is press-fit on the hub cylindrical portion55bextending axially away from the inner raceway surface55aof the wheel hub55. Double row rolling elements53and53, held by cages57,57, are arranged between the outer and inner raceway surfaces51aand51a;55aand56a, respectively.

The wheel hub55has an integrally formed wheel mounting flange54to mount a wheel (not shown). Hub bolts54a, to secure the wheel, are rigidly secured on the wheel mount flange54at an equidistant along its periphery. A serration55cis formed on the inner circumferential surface of the wheel hub55. A stem portion61of an outer joint member60, which forms a part of a constant velocity universal joint (not shown), is inserted into the wheel hub serration55. Seals58and59are arranged at both ends of the outer member51to prevent leakage of grease contained within the bearing as well as ingress of rain water or dust into the bearing.

The seal59on the inboard side, as shown in an enlarged view ofFIG. 6, is fit into the inner circumference at the end of the outer member51. The seal59includes a first sealing plate62and a second sealing plate63having a “L”-shaped cross-section. The second sealing plate63has a cylindrical portion63afit onto the outer circumference of the inner ring56. A standing portion63bextends radially outward from the cylindrical portion63a. A magnetic encoder64is adhered, via vulcanized adhesion, on the outer surface of the standing portion63b. The magnetic encoder64is formed from a rubber magnet in which magnetic N and S poles are alternately arranged along the circumferential direction.

The first sealing plate62includes a metal core65having a substantially “L”-shaped cross-section. A sealing member66, including a side lip66a, is in sliding contact with the inner side surface of the standing portion63bof the second sealing plate63. A pair of radial lips66band66cis in sliding contact with the cylindrical portion63aof the second sealing plate63.

An annular sensor holder69is mounted on one end of the outer member51. The annular sensor holder69includes a fitting cylinder67and a holding portion68connected to the fitting cylinder67. The fitting cylinder67has an annular configuration with an “L”-shaped cross-section. The fitting cylinder67includes a cylindrical portion67aand a flange portion67b, which extends radially inward from the cylindrical portion67a.

The holding portion68is made from synthetic resin molded into an annular body. A wheel speed sensor70is embedded into the resin. The wheel speed sensor70is arranged opposite to a magnetic encoder64with a predetermined air gap between the two. The wheel speed sensor70includes a magnetic detecting element, such as a Hall element, a magnetic resistance element (MR element) etc., which changes characteristics in accordance with the flowing direction of the magnetic flux. Also included is an IC with a waveform shaping circuit to shape the output waveform of the magnetic detecting element.

A labyrinth seal is formed by a small gap71arranged between the flange portion67bof the fitting cylinder67and the opposed end surface of the inner ring56. The seal prevents ingress of foreign matter, such as magnetic powder, into a space between the magnetic encoder64and the detecting portion of the wheel speed sensor70from outside of the bearing apparatus and before the stem portion61of the outer joint member60is inserted into the wheel hub55, which includes a course where the bearing apparatus is transferred to an assemble line of an automobile manufacturer. Accordingly, this improves the detecting reliability of the rotational speed of the wheel.

Although the wheel bearing apparatus incorporated with a wheel speed detecting apparatus of the prior art has superior effects mentioned above, it is impossible to prevent ingress of foreign matter, such as magnetic powder, into a space between the magnetic encoder64and the detecting portion of the wheel speed sensor70from outside of the bearing apparatus and under severe circumstances during real running of the vehicle.

SUMMARY

It is, therefore, an object of the present disclosure to provide a wheel bearing apparatus with a wheel speed detecting apparatus which is small in size and can prevent ingress of foreign matter into the wheel speed detecting region. Thus, this improves the durability as well as the reliability of the detector.

According to the present disclosure, a wheel bearing apparatus with a wheel speed detecting apparatus comprises an outer member with an integrally formed body mounting flange. Double row outer raceway surfaces are formed on the inner circumferential surface of the outer member. An inner member includes a wheel hub, formed with an integral wheel mounting flange at one end and a cylindrical portion axially extending from the wheel mount flange, and an inner ring fit on the cylindrical portion of the wheel hub. Double row inner raceway surfaces are formed on the outer circumferential surfaces of the wheel hub and inner ring, respectively, opposite to the double row outer raceway surfaces. Double row rolling elements are arranged between the outer and inner raceway surfaces. An encoder is mounted on the outer circumferential surface of the inner ring. A sensor holder is arranged on the end of the outer member opposite to the encoder. The sensor holder includes an annular fitting member and a holding portion formed from synthetic resin molded integrally with the annular fitting member. A wheel speed detecting sensor is embedded in the resin and is positioned opposite to the encoder, via a predetermined gap. The encoder has its characteristics varying alternately and equidistantly along its circumferential direction. A seal is arranged at the inboard side of the encoder. The seal includes a first sealing plate and a second sealing plate fit, respectively, on the annular fitting member and the inner ring. The plates are arranged opposite to one another. The tip end of the annular fitting member engages the holding portion.

The wheel bearing apparatus with a wheel speed detecting apparatus comprises an encoder mounted on the outer circumferential surface of the inner ring. A sensor holder is arranged on the end of the outer member opposite to the encoder. The holder includes an annular fitting member and a holding portion formed from synthetic resin molded integrally with the annular fitting member. A wheel speed detecting sensor is embedded in the resin and arranged opposite to the encoder, via a predetermined gap. The encoder has its characteristics varying alternately and equidistantly along its circumferential direction. A seal is arranged at the inboard side of the encoder. The seal includes a first sealing plate and a second sealing plate fit, respectively, on the annular fitting member and the inner ring and arranged to oppose one another. The tip end of the annular fitting member engages the holding portion. Thus, it is possible to prevent ingress of foreign matter, such as magnetic powder, into a space between the magnetic encoder and the detecting portion of the wheel speed sensor from outside of the bearing apparatus although before the stem portion of the outer joint member is inserted into the wheel hub, which includes a course where the bearing apparatus is transferred to an assemble line of an automobile manufacturer and also under severe circumstances during real running of the vehicle. Thus, it is also possible to increase the strength of the connection between the annular fitting member and the holding portion. This remarkably improves the detection reliability of the wheel rotation speed.

The annular fitting member includes a cylindrical fitting portion press fit onto the outer circumferential surface of the outer member. A flange portion extends radially inward from the fitting portion. The flange portion is adapted to contact with the end face of the outer member. A cylindrical portion extends axially from the flange portion. The first sealing plate is fit into the cylindrical portion. Thus, it is possible to reduce the radial size of the wheel bearing apparatus and to simplify the structure of the wheel speed sensor and its associated parts. This further improves the workability of the assemble.

The tip end of the cylindrical portion of the annular fitting member extends radially outward from the cylindrical portion in an inclined direction. The plastic resin, forming the holding portion, is molded so that it envelopes the tip end of the cylindrical portion. The annular fitting member has an engaging portion which extends radially outward from the cylindrical portion. Alternatively, the tip end of the engaging portion is caulked onto the holding portion after the holding portion has been molded onto the annular fitting member. Thus, it is possible to increase the strength of the connection between the annular fitting member and the holding portion. Thus, this prevents separation of the two due to vibration of the wheel bearing apparatus during transportation and handling.

The second sealing plate has a substantially “L” shaped cross-section. A cylindrical portion is adapted to fit into the inner ring. A standing portion extends radially outward from the cylindrical portion. Sealing lips of a sealing member are mounted on the first sealing plate. The lips slidably contact the second sealing plate. Thus, it is possible to improve the sealability of the wheel bearing apparatus. This prevents leakage of grease contained within the bearing as well as ingress of rain water or dust into the bearing.

The wheel bearing apparatus with a wheel speed detecting apparatus comprises an outer member with an integrally formed body mounting flange. Double row outer raceway surfaces are formed on the inner circumferential surface of the outer member. An inner member includes a wheel hub with an integrally formed wheel mounting flange at one end and a cylindrical portion axially extending from the wheel mount flange. An inner ring is fit onto the cylindrical portion of the wheel hub. Double row inner raceway surfaces are formed on the outer circumferential surfaces of the wheel hub and inner ring, respectively, opposite of the double row outer raceway surfaces. Double row rolling elements are rotatably arranged between the outer and inner raceway surfaces. An encoder is mounted on the outer circumferential surface of the inner ring. A sensor holder is arranged on the end of the outer member opposite to the encoder. The holder includes an annular fitting member and a holding portion formed from synthetic resin molded integrally with the annular fitting member. A wheel speed detecting sensor is embedded in the resin and positioned opposite of the encoder, via a predetermined gap. The encoder has its characteristics varying alternately and equidistantly along its circumferential direction. A seal is arranged at the inboard side of the encoder. The seal includes a first sealing plate and a second sealing plate fit, respectively, on the annular fitting member and the inner ring and arranged opposite to each other. The tip end of the annular fitting member engages the holding portion. Accordingly, it is possible to prevent ingress of foreign matter, such as magnetic powder, into a space between the magnetic encoder and the detecting portion of the wheel speed sensor from the outside of the bearing apparatus although before the stem portion of the outer joint member is inserted into the wheel hub, which includes a course where the bearing apparatus is transferred to an assemble line of an automobile manufacturer, and also under severe circumstances during real running of the vehicle. Thus, it is also possible to increase the strength of the connection between the annular fitting member and the holding portion. Thus, this remarkably improves the detection reliability of the wheel rotational speed.

A wheel bearing apparatus incorporated with a wheel speed detecting apparatus comprises an outer member with an integrally formed body mounting flange. Double row outer raceway surfaces are formed on the inner circumferential surface of the outer member. An inner member includes a wheel hub with an integrally formed wheel mounting flange at one end and a cylindrical portion axially extending from the wheel mount flange. An inner ring is fit onto the cylindrical portion of the wheel hub. Double row inner raceway surfaces are formed on the outer circumferential surfaces of the wheel hub and inner ring, respectively, opposite to the double row outer raceway surfaces. Double row rolling elements are rotatably arranged between the outer and inner raceway surfaces. An encoder is mounted on the outer circumferential surface of the inner ring. A sensor holder is arranged on the end of the outer member opposite to the encoder. The holder includes an annular fitting member and a holding portion formed from synthetic resin molded integrally with the annular fitting member. A wheel speed detecting sensor is embedded in the resin and is positioned opposite to the encoder, via a predetermined gap. The encoder has its characteristics varying alternately and equidistantly along its circumferential direction. A seal is arranged at the inboard side of the encoder. The seal includes a first sealing plate and a second sealing plate fit, respectively, on the annular fitting member and the inner ring and arranged to oppose one another. The tip end of the annular fitting member engages the holding portion.

DETAILED DESCRIPTION

Preferred embodiments of the present disclosure will be described with reference to accompanied drawings.

FIG. 1is a longitudinal-section view of a first embodiment of a wheel bearing apparatus with a wheel speed detecting apparatus.FIG. 2is a partially enlarged longitudinal-section view ofFIG. 1. In the description of the present disclosure, an outer side of a bearing apparatus, when it is mounted on a vehicle, is referred to as the “outboard” side (the left side in the drawing). An inner side of the bearing apparatus, when it is mounted on a vehicle, is referred to as the “inboard” side (the right side in the drawing).

The wheel bearing apparatus with a wheel speed detecting apparatus for a driving wheel where a wheel hub1and a double row rolling bearing2are formed as a unit arrangement. Thus, it has a so-called “third generation” structure.

The double row rolling bearing2includes an outer member4, an inner member3, and double row rolling elements (balls)5and5. The outer member4is made of medium carbon steel including carbon of 0.40˜0.80 wt % by weight. A body mounting flange4bis integrally formed at its outer circumferential surface. The body mounting flange4bis adapted to be mounted on a knuckle N. Also, double row outer raceway surfaces4aand4aare formed on its inner circumferential surface. The double row outer raceway surfaces4aand4aare hardened by high frequency induction quenching to have a surface hardness of 54˜64 HRC.

The inner member3includes the wheel hub1and an inner ring6press fit onto the wheel hub1. The wheel hub1is integrally formed with a wheel mounting flange7. The flange7mounts a wheel (not shown) at its outboard end. Hub bolts7asecure it. The bolts7aare circumferentially and equidistantly positioned about the flange7. The outer circumferential surface of the wheel hub1is formed with one inner raceway surface1a(outboard side) corresponding to one of the double row outer raceway surfaces4aand4a. A cylindrical portion1bextends axially from the inner raceway surface1a.

The inner ring6is press-fit onto the cylindrical portion1bvia a predetermined interference fit. The inner ring6is formed with the other inner raceway surface6a(inboard side) corresponding to the other of the double row outer raceway surfaces4aand4a. The inner ring6is axially immovably secured relative to the wheel hub1by the caulked portion8. The caulked portion8is formed by plastically deforming the cylindrical portion1bof the wheel hub1. Thus, a so-called self-retaining structure is formed. The self-retaining structure enables a reduction in weight and size of the bearing apparatus. This is due to the fact that it is unnecessary to control an amount of preload on the bearing apparatus by tightly fastening the inner ring6using a nut as in a conventional manner.

The double row rolling elements5and5are contained between the outer member outer raceway surfaces4aand4aand the oppositely arranged inner raceway surfaces1aand6a. The rolling elements5are held by cages9and9. Seals10and11are arranged at the ends of the outer member4to prevent leakage of grease contained within the bearing apparatus as well as ingress of rain water or dust into the bearing.

The wheel hub1is made of medium carbon steel such as S53C including carbon of 0.40˜0.80 wt % by weight. The wheel hub1is formed with a hardened layer having a surface hardness of about 54˜64 HRC, by high frequency induction hardening. The hardened surface is from the seal land portion, to which the outboard seal10sliding contacts, to the inner raceway surface1aand cylindrical portion1b. The caulked portion8is not heat treated. The caulked portion8has its surface hardness of less than or equal to 25 HRC. Thus, it is possible not only to improve the wear resistance of the seal land forming the base of the wheel mounting flange7but to provide a sufficient mechanical strength against the rotary bending load applied to the wheel mount flange7. Thus, this improves the durability of the wheel hub1. In addition, it is possible to improve the workability of the caulked portion8during plastic deformation and to prevent the generation of cracks during deformation. Thus, this improves the quality reliability.

The wheel hub1is formed with a serration (or spline)1con its inner peripheral surface. An outer joint member12, forming a constant velocity universal joint, is inserted into the serration1c. A shoulder13on the outer joint member12abuts the caulked portion8of the wheel hub1. The outer joint member12is axially secured with the wheel hub1by a nut14.

A sensor holder15is fit on the inboard end of the outer member4as shown inFIG. 2. The sensor holder15includes an annular fitting member16and a holding portion17. The annular fitting member16is formed wholly as an annular body. The annular fitting member16includes a cylindrical fitting portion16apress-fit on the outer circumferential surface of the outer member4. A flange portion16bextends radially inward from the fitting portion16a. The flange portion16bis adapted to be in close contact with the end surface of the outer member4. A cylindrical portion16cextends axially from the flange portion16b. The annular fitting member16is press-formed from stainless steel having corrosion resistance. The holding portion17is integrally molded with the annular fitting member16. Several apertures18are provided on the cylindrical portion16cto enable the holding portion to pass through the fitting member16. The seal11is arranged between the cylindrical portion16cand the inner ring6. The sensor holder15is press fit onto the inboard end of the outer member4. The flange portion16bof the annular fitting member16is in close contact with the end face of the outer member4.

A wheel speed detecting sensor20is embedded within the holding portion17. The detecting sensor20is positioned opposite to a magnetic encoder19, via a predetermined radial gap between the two. The wheel speed sensor20includes a magnetic detecting element such as a Hall element, a magnetic resistance element (MR element) etc. which changes characteristics in accordance with the flowing direction of the magnetic flux. Also, an IC, with a waveform shaping circuit for shaping the output waveform of the magnetic detecting element, is incorporated with the sensor20.

The inboard seal11has first and second annular sealing plates21and22. Each plate has a substantially “L”-shaped cross-sectional configuration and are arranged to oppose one another. The second sealing plate22includes a cylindrical portion22apress fit onto the inner ring6. A standing portion22bextends radially outward from the cylindrical portion22a. The tip of the standing portion22bopposes the cylindrical portion21aof the first sealing plate21, via a small radial gap, and forms a labyrinth seal23. The second sealing plate22is made by press-forming austenitic stainless steel sheet (JIS SUS 304 etc.) or preserved cold rolled sheet (JIS SPCC etc.).

The first sealing plate21includes a cylindrical portion21apress fit into the cylindrical potion16cof the annular fitting member16of the sensor holder15. A standing portion21bextends radially inward from one end of the cylindrical portion21a. A sealing member24, having a side lip24a, grease lip24band a medium lip24cmade of elastic material such as rubber etc., is adhered to the sealing plate21, via vulcanized adhesion. The side lip24ais in sliding contact with the standing portion22bof the second sealing plate22. The grease lip24band medium lip24care in sliding contact with the cylindrical portion22aof the second sealing plate22.

A steel base25is arranged at the outboard side of the seal11opposite to and sandwiching the holding portion17of the sensor holder15. The base25includes a cylindrical portion25aadapted to be press fit onto the inner ring6and a standing portion25bextending radially outward from the cylindrical portion25a. The steel base25is made by press-forming a ferritic stainless steel sheet (JIS SUS 430 etc.) or preserved cold rolled sheet (JIS SPCC etc.). A magnetic encoder19is adhered, via vulcanized adhesion, onto the outboard side surface of the standing portion25b. The magnetic encoder19is formed from an elastomer such as rubber etc. which includes mixed or mingled magnetic powder. The magnetic encoder19has N and S poles, alternately arranged along its circumference direction. The magnetic encoder forms a rotary encoder to detect the wheel rotational speed.

According to this embodiment, since the holding portion17is integrally molded with the annular fitting member16, the wheel speed sensor20is embedded in the holding portion17. The seal11is fit into the inboard side of the sensor20. The magnetic encoder19is arranged at the outboard side of the seal11with the holding portion17sandwiched therebetween. Thus, it is possible to prevent ingress of foreign matter, such as magnetic powder, into a space between the magnetic encoder and the detecting portion of the wheel speed sensor from the outside of the bearing apparatus although before the stem portion of the outer joint member is inserted into the wheel hub, which includes a course where the bearing apparatus is transferred to an assemble line of an automobile manufacturer, and also under severe circumstances during real running of the vehicle. Thus, it is possible to improve the detection reliability of the wheel speed. Also, it is possible to reduce the radial size of the wheel bearing apparatus and to simplify the structure of the wheel speed sensor and its associated parts. This further improves the workability of the assemble.

The tip end26of the cylindrical portion16cof the annular fitting member16extends radially outward on an incline from the cylindrical portion16c. The plastic resin forming the holding portion17, as it is molded, envelopes the tip end26of the cylindrical portion16c. Thus, it is possible to increase the strength of connection between the annular fitting member16and the holding portion17. This prevents separation of the two due to vibration of the wheel bearing apparatus during transportation and handling.

Although it is exemplary shown in this embodiment that the wheel rotation speed sensor20includes the magnetic encoder19and the magnetic detecting element such as Hall effect element, the wheel speed detecting apparatus is not limited to such a structure and may be a passive type apparatus comprising a magnetic encoder, magnets, or annular coils, etc. Also, although it is exemplary shown in this embodiment as a wheel bearing apparatus for a driving side wheel, the present disclosure can be applied to a wheel bearing apparatus for a driven side wheel if it has an inner ring rotation type structure.

FIG. 3is an enlarged view of a second embodiment of the wheel bearing apparatus with a wheel speed detecting apparatus. This second embodiment is different from the first embodiment only in the structure of the annular fitting member. Accordingly, same reference numerals are also used in the second embodiment to designate the same parts performing the same functions of the parts as those used in the first embodiment.

A sensor holder27includes an annular fitting member16′ and a holding portion28integrally formed with the annular fitting member16′. The annular fitting member16′ is formed wholly as an annular body. The annular fitting member16′ includes a cylindrical fitting portion16apress-fit onto the outer circumferential surface of the outer member4. A flange portion16bextends radially inward from the fitting portion. A cylindrical portion16cextends axially from the flange portion16b. An upstanding engaging portion16dextends radially outward from the cylindrical portion16c. The holding portion28is integrally molded with the annular fitting member16′ by providing several apertures18on the cylindrical portion16c. The seal11is arranged between the cylindrical portion16cof the annular fitting member16′ of the sensor holder27and the inner ring6. The sensor holder27is press fit onto the inboard end of the outer member4. The flange portion16bof the annular fitting member16′ is in close contact with the end face of the outer member4.

The tip end29of the engaging portion16dof the annular fitting member16′ is caulked onto the holding portion28after the holding portion28has been molded onto the annular fitting member16′. Thus, it is possible to increase the strength of the connection between the annular fitting member16′ and the holding portion28. This prevents separation of the two similarly to the first embodiment.

FIG. 4is an enlarged view showing a third embodiment of the wheel bearing apparatus with a wheel speed detecting apparatus. This embodiment differs from the first embodiment (FIG. 2) only in the structure of the detecting portion. Accordingly, the same reference numerals are used in the third embodiment to designate the same parts performing the same functions of the parts used in the first embodiment.

A sensor holder30is formed with an annular configuration. The sensor holder30includes the annular fitting member16and a holding portion31integrated with the annular fitting member16. The sensor holder30is mounted on the inboard end of the outer member4. The holding portion31is formed from synthetic resin and integrally molded with the annular fitting member16by providing several apertures18on the cylindrical portion16cof the annular fitting member16. A wheel speed detecting sensor35is embedded within the holding portion31. The sensor35is positioned opposite to a magnetic encoder34, via a predetermined radial gap between the two. The wheel speed sensor35includes comprises a magnetic detecting element such as a Hall element, a magnetic resistance element (MR element) etc. which changes characteristics in accordance with the flowing direction of magnetic flux. Also, an IC, with a waveform shaping circuit to shape the output waveform of the magnetic detecting element, is incorporated with the sensor35.

An inboard seal32includes first and second annular sealing plates21and33. Each plate has a substantially “L”-shaped cross-sectional configuration and are mounted, respectively, on the sensor holder30and the inner ring6so that they face opposite toward each other. The second sealing plate33includes a cylindrical portion33afit onto the inner ring6. Another cylindrical portion33b, of larger diameter, extends axially from the cylindrical portion33a. A standing portion33cextends radially outward from the cylindrical portion33b. The tip of the standing portion33copposes the cylindrical portion21aof the first sealing plate21, via a small radial gap, and forms a labyrinth seal23. The second sealing plate22is made by press-forming a ferritic stainless steel sheet (JIS SUS 430 etc.) or preserved cold rolled sheet (JIS SPCC etc.).

The side lip24aon the first sealing plate21is in sliding contact with the standing portion33cof the second sealing plate33. The grease lip24band medium lip24care in sliding contact with the cylindrical portion33bof larger diameter of the second sealing plate33. A magnetic encoder34is adhered, via vulcanized adhesion, on the outboard side surface of the cylindrical portion33a. The magnetic encoder34is formed of an elastomer such as rubber etc. which includes mixed or mingled magnetic powder. The magnetic encoder34has N and S poles alternately arranged along its circumference direction. The magnetic encoder forms a rotary encoder to detect the wheel rotational speed.

The holding portion31is integrally molded with the annular fitting member16. The wheel speed sensor35is embedded in the holding portion31. The seal32is fit into the sensor holder30from the inboard side of the sensor35. Thus, it is possible to prevent ingress of foreign matter, such as magnetic powder, into a space between the magnetic encoder and the detecting portion of the wheel speed sensor from the outside of the bearing apparatus although before the outer joint member12is inserted into the wheel hub1, which includes a course where the bearing apparatus is transferred to an assemble line of an automobile manufacturer, and also under severe circumstances during real running of the vehicle.

The wheel bearing apparatus, with a wheel speed detecting apparatus, of the present disclosure can be applied to any type of the wheel bearing apparatus where the wheel speed detecting apparatus is self-contained, irrespective of use in a driving wheel or driven wheel having an inner ring rotational structure.

The present disclosure has been described with reference to the preferred embodiments. Obviously, modifications and alternations will occur to those of ordinary skill in the art upon reading and understanding the above detailed description. It is intended that the present invention be construed to include all such alternations and modifications insofar as they come within the scope of the appended claims or their equivalents.