Bearing Assembly for Vehicle

1. Field of the Invention

The present invention relates to improvements in a bearing assembly for a wheel provided with speed detecting means, that is, a bearing assembly provided with a pulser gear for detecting the number of rotations of the wheel.

2. Related Background Art

In the brakes are suddenly applied when a vehicle is running, particularly, when the vehicle is running on a snowy road or ice in wintertime, the wheels of the vehicle may be locked before the vehicle stops. If in such case, the rear wheels are locked, stability will be reduced, and if the front wheels are locked, maneuverability will be lost, and in any case, the vehicle will become a very unstable condition.

In order to prevent such a phenomenon, there is known a so-called anti-lock apparatus in which a pulser gear is fixed to a rotatable wheel rotatable with the wheel of a vehicle and the number of rotations of the wheel is sensed by a sensor to thereby control the braking force of the wheel.

Heretofore, a plurality of balls have been interposed, for example, between an outer race and an inner race which are rotalable with the wheel, and a pulser gear having concave and convex portions alternately formed circumferentially on the outer peripheral surface thereof has been mounted on the outer race, and the number of rotations of the wheel has been detected by a sensor disposed in proximity to pulser gear.

However, with a bearing whose inner race is rotated by the running of the vehicle, it is impossible in the above-described method to measure the speed of the vehicle. Also, where a seal member is used to prevent muddy water from entering into the interior of the bearing, the sliding portion (for example, the inner race) of the seal lip becomes rusty due to muddy water or the like, and this leads to the problem that the sealing effect is reduced to reduce the service life of the bearing.

The present invention has been made with a view to eliminate the above-noted problem peculiar to the prior art, that is, to prevent the seal sliding surface in a bearing assembly for a wheel from rusting.

In the present invention, an annular member provided with a pulser gear also forms a seal portion (which may be of the contact type or the now-contact type) between it and the outer race. That is, the annular member is fixedly fitted to the inner race, and a seal portion is formed between the portion surrounding the outer race and the outer race and a pulser gear portion is formed on the outer peripheral edge thereof.

According to the present invention, the seal portion of the bearing is protected by an annular member provided with a pulser gear for detecting the number of rotations (the speed) of the wheel so that it is not exposed to rainwater or muddy water and therefore, the entry of muddy water or the like into the bearing is prevented and the lip sliding surface of the seal member is prevented from rusting and thus, the service life of the bearing is improved. Moreover, this can be accomplished without substantially changing the structure of the conventional bearing assembly, and in some cases, while utilizing it.

FIG. 1 is a front cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a front view of a second annular member (54) in the first embodiment.

FIG. 3 is a cross-sectional view taken along line III--III in FIG. 2.

FIGS. 4 and 5 are front cross-sectional views showing a second and a third embodiment, respectively, of the present invention.

Some embodiments of the present invention will hereinafter be described with reference to the drawings

The present invention can of course be suitably changed and improved within a scope which does not mar the gist thereof.

Referring to FIG. 1 which is a front cross-sectional view of a bearing assembly, reference numeral 10 designates an inner race which comprises a body 18 having a radially outwardly extending flange portion 12, a ball track groove 14 and a stepped portion 16 at one end thereof, and an annular member 24 fitted to the stepped portion 16 and having a ball track groove 22. An outer race 26 is disposed outside and concentrically with the inner race 10, and has ball track grooves 28 and 30 opposed to said ball track grooves 14 and 22, respectively, and a radially outwardly extending protrusion 31. A plurality of balls 32 and 34 and retainers 36 and 38 are interposed between the pair of opposed ball track grooves 14 and 28 and between the pair of opposed ball track grooves 22 and 30, respectively.

The bearing comprising the inner race 10, the outer race 26 and the balls 32, 34 is a so-called double row angular contact bearing and is mounted on a brake drum and a disk brake by means of a bolt, not shown, extending through a through-hole 40 in the flange portion 12.

A seal member 42 is interposed between one end (the right end as viewed in FIG. 1) of the annular member 24 of the inner race 10 and that portion of the outer race 26 which is opposed thereto, to prevent rainwater from entering into the interior of the bearing through this gap.

A seal member 50 is interposed between the other end (the left end as viewed in FIG. 1) of the outer race 26 and that portion of the inner race body 18 which is opposed thereto, and this seal member 50 comprises a first annular member 52 of L-shaped cross-section fitted to the outer race 26, a second annular member 54 made of a metal and fitted to the inner race body 18, and an elastic member 56 interposed between the two annular members. The second annular member 54, as shown in FIGS. 2 and 3, has a first cylindrical portion 60 extending parallel to the axis thereof, a first flange portion 62 extending radially outwardly therefrom, a second cylindrical portion 64 extending parallel to a first cylindrical portion 60 therefrom, a second flange portion 66 extending parallel to the first flange portion 62 therefrom, and a number of radial convex portions 68 formed circumferentially at predetermined intervals on that surface of the second flange portion 66 which is opposite to the surface thereof on which the second cylindrical portion 64, etc. are present. These convex portion 68 are formed by press-forming magnetic metal plate with a tapered surface 55 thereof being abutted against a molding (not shown). However, it is possible to form through holes by press-forming instead of the convex portion 68.

The second annular member 54, as shown in FIG. 1, is mounted to the inner race 10, i.e., the bearing, with the first cylindrical portion 60 fitted to the inner race body 18, the first flange portion 62 extends proximately to the end portion of the outer race 26, and the second cylindrical portion 64 extends proximately to the outer peripheral surface of the outer race 26, each of them forming labyrinth seals 65 and 67. The second flange portion 66 extends proximately to the surface of the outer race protrusion 31.

The protrusion 31 is formed with a through-hole 33 in the axial direction thereof, in which a sensor 70 is mounted and is proximate and opposed to the second flange portion 66 and the convex portions 68 thereon.

Operation of the present embodiment will now be described. When wheels are rotated, the inner race 10 is rotated relative to the outer race 26 by the rolling of the balls 32 and 34 through the bolt extending through the through-hole 40. During the rotation of the inner race 10, the second annular member 54 rotates therewith (the first annular member 52 does not rotate) and the convex portions 68 on the second flange portion 66 successively pass the front of the sensor 70 and therefore, by calculating the frequency of passage of the convex portions 68 per unit time, it is possible to detect the speed of rotation of the wheel made integral with the second annular member 54, i.e., the inner race 10.

As regards the entry of rainwater into the interior of the bearing, the convex portions 68 on the second flange portion 66 are formed radially and therefore, even if rainwater collects in the concave portions between adjacent convex portions, such rainwater will be sling off radially outwardly by a centrifugal force based on the rotation of the second annular member 54 (the water shake-off effect). Also, since the labyrinth seals 65 and 67 are formed in mutually orthogonal directions between the first flange portion 62 and the second cylindrical portion 64 and the outer race 26, it is difficult for rainwater to reach the location between the left end portion of the outer race 26 and that portion of the inner race body 18 which is opposed thereto Moreover, even if rainwater reaches this location, the entry of the rainwater into the interior of the bearing will be prevented by a seal member formed by the first cylindrical portion 60 of the first annular member 52, the second annular member 54 and the elastic member 56.

Also, during the rotation of the inner race 10, the second annular member 54 rotates therewith and the outer peripheral surface of that portion which is contacted by the elastic member 56 (the first cylindrical portion 60) provides a seal sliding surface. However, as described above, it is difficult for rainwater or muddy water to reach the seal member 50 and therefore, this seal sliding surface is prevented from being damaged and the sealing property is improved

Second and third embodiments of the present invention will now be described with reference to FIGS. 4 and 5.

A feature of the second embodiment shown in FIG. 4 is that a second annular member 80 comprises a first cylindrical portion 82 fitted to an inner race body 18, a first flange portion 84 extending therefrom along the end surface of an outer race 26 and a second cylindrical portion 86 extending therefrom along the outer peripheral surface of the outer race 26, and convex portions 88 are provided circumferentially at intervals on the second cylindrical portion. Thus, the sensor 70 is disposed radially of the outer race 26 as indicated by dots-and-dash line in FIG. 4.

According to this embodiment, the construction of the second annular member 80 is simple and the manner in which the sensor 70 is disposed is flexible.

Next, in the embodiment shown in FIG. 5, the construction of a second annular member 90 is similar to that in the embodiment shown in FIGS. 1-3, whereas a first cylindrical portion 92 fitted to the inner race body 18 does not constitute a seal member 94, but the seal member 94 is constituted by a first annular member 52 and an elastic member 56.

According to this embodiment, the seal member 94 and speed detecting means bear their functions discretely and therefore, the construction of each of them is simple and the operation thereof is also stable.