Sealing device for a hub/wheel assembly and hub/wheel assembly having such a sealing device

A sealing device for a hub/wheel assembly with a roller bearing. The sealing device includes a guard, made of plastic. The guard is coupled to an outer ring of the bearing to seal off the bearing. The guard has a cylindrical mounting wall with an outer lateral surface coupled to an inner lateral surface of a collar of the outer ring, and a snap-engagement step for engaging with the collar made along the outer lateral surface so that it snap-fits in a contoured annular groove made along the collar about the axis. An annular gasket is made of elastomer and co-injection-molded inside an annular groove made in the cylindrical mounting wall on the same side as the snap-engagement step.

This application claims priority to Italian patent application no. 102017000099283 filed on Sep. 5, 2017, the contents of which are fully incorporated herein by reference.

TECHNOLOGICAL FIELD

The present invention relates to a sealing device for a hub/wheel assembly. The invention also relates to a bearing/hub assembly having such a sealing device.

The present invention is particularly, although not exclusively, applicable to the field of hub/wheel assemblies for motor vehicles having a roller bearing for a non-driving wheel. In such applications, the inner ring of the bearing is rigidly secured to the shaft of the wheel and transmits to the latter the consequent rotary movement, while the outer ring of the bearing is rigidly secured to a fixed hub, for example a hub of a motor vehicle suspension. The text below will refer, by way of example, to this specific use, although it remains generally applicable.

BACKGROUND

Since the invention applies in this case to non-driving wheels which thus do not have a through-shaft along the axis of the bearing, the relevant sealing devices have an axisymmetric “cup” shape such that they laterally close off the outer ring of the bearing and create a static seal to protect the bearing from any ambient contamination (water, dust, dirt, etc.).

In their most generic form, the sealing devices comprise a plastic guard, almost cup-shaped, which is mounted on a collar of the outer ring of the roller bearing by press-fitting with interference and they include, in particular:a cylindrical mounting wall, coaxial with an axis of symmetry of the bearing, which is coupled by means of the press-fitting with the collar of the outer ring of the bearing;an annular reading wall, transverse to the axis of symmetry and interposed between a detection sensor mounted on the outside of the bearing and a phonic wheel mounted on the inside of the bearing, anda discoidal end wall internal to the annular reading wall and facing, transversely to the axis of symmetry, an inner ring of the bearing.

Although in earlier embodiments, sealing devices were designed to perform their function only by means of coupling by interference with the bearing, in some current embodiments, such as that described for example in JP2009216208A, the sealing devices have an annular locking step, which is rigidly secured to the cylindrical wall and may be snap-fitted in the collar of the outer ring of the bearing to axially secure the guard to the outer ring, and they are also provided with an adhesive material distributed around the cylindrical wall to subsequently seal the guard against the collar of the outer ring of the bearing.

However, the use of this adhesive material is not particularly good from the environmental viewpoint, and moreover requires considerable precautions during the assembly of the sealing devices, to the detriment of production times.

BRIEF SUMMARY OF THE PRESENT INVENTION

It is an aim of the present invention to produce a sealing device for a hub/wheel assembly which does not have the abovementioned disadvantages.

A sealing device for a hub/wheel assembly with a roller bearing, which has the features of the present invention defined as follows:A sealing device for a hub/wheel assembly with a roller bearing, the sealing device having a central axis, the sealing device comprising:a guard coupled to an outer ring of the bearing so as to seal off the bearing, the guard having a cylindrical mounting wall including a first lateral surface coupled to a second lateral surface of a collar of the outer ring;a snap-engagement for engaging the guard with the collar made along the first lateral surface so that it snap-fits in a contoured annular groove made along the collar about the axis; andan annular sealing arrangement made of an elastomer and arranged inside an annular groove made in the cylindrical mounting wall on the same side as the snap-engagement, the guard being made of plastic and the annular sealing arrangement being co-injection-molded inside the groove and adhering chemically to the plastic of the guard.

Further embodiments of the invention, which are preferred and/or particularly advantageous, are described according to the features set forth as follows:

In another aspect, the annular groove is made in the cylindrical mounting wall at an axial distance determined with respect to the snap-engagement means to allow radial deformation of the cylindrical mounting wall with respect to the collar so as to move the annular sealing arrangement away from the collar until the snap-engagement means are snap-fitted in the contoured annular groove.

In yet another aspect, the snap-engagement and the annular sealing arrangement inside the groove are arranged on a first outer lateral surface of the cylindrical mounting wall and the contoured annular groove is made along the collar about the axis on a second inner lateral surface of the collar.

In yet another aspect, the contoured annular groove has an axial stop element that, when applicable, comes into contact with an end of the cylindrical mounting wall.

In yet another aspect, the snap-engagement and the annular sealing arrangement inside the groove are arranged on a first inner lateral surface of the cylindrical mounting wall and the contoured annular groove is made along the collar about the axis on a second outer lateral surface of the collar.

In yet another aspect, the snap-engagement is defined by a step which is circumferentially continuous, in the form of an annular ridge, or, preferably, by a step which is circumferentially discrete, in the form of bumps which are angularly separated from one another, and this step can interact by snap-fitting with the contoured annular groove to axially engage the guard with the collar.

In yet another aspect, the snap-engagement is defined by a step which is circumferentially continuous, in the form of a step which is circumferentially discrete, in the form of bumps, which are angularly separated from one another, and this step can interact by snap-fitting with the contoured annular groove to axially engage the guard with the collar.

In yet another aspect, the sealing device can be integrated into a roller bearing that is installed on a hub/wheel assembly.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

With reference toFIG. 1, a sealing device for a hub/wheel assembly2is shown with the general reference sign1.

The assembly2has a roller bearing3comprising an outer ring4, coaxial with an axis A of rotation of the bearing3, an inner ring5coaxial with the outer ring4, and a plurality of roller elements8, for example balls, interposed between the outer ring4and the inner ring5to allow the inner ring5to rotate, in rotational use, with respect to the outer ring4, in fixed use. The outer ring4of the bearing3has a collar41, which is defined by a cylindrical outer lateral surface42, an annular end surface43, and a cylindrical inner lateral surface44. As for the inner ring5, it has a phonic wheel51, which is rigidly secured to the inner ring5and has a mounting support52defined, preferably, by a plate bent in the shape of an L, and a ring53of ferromagnetic material fastened to the support52.

The sealing device1, according to the present invention, has the axis A as central axis and comprises a guard6, which is coupled to the outer ring4of the bearing3, has substantially a cup shape, and is made of plastic, preferably PA66 or PPA reinforced with glass fibers to provide the necessary mechanical strength and dimensional stability.

As shown also inFIG. 2, the guard6comprises:a cylindrical mounting wall61, coaxial with the axis A, which is coupled to the collar41of the outer ring4of the bearing3, and has an inner lateral surface61aand an outer lateral surface61b;an annular reading wall63, transverse to the axis A of symmetry, connected to the cylindrical wall61and interposed between a detection sensor (not shown) mounted on the outside of the bearing3and the phonic wheel51mounted on the inside of the bearing3; anda discoidal end wall64which is internal, in a radial direction, to the annular reading wall63and which faces, transversely to the axis A, the inner ring5of the bearing3.

The guard6further comprises a frustoconical wall65for connecting the annular wall63to the end wall64, the conicity of which tapers on the side away from the bearing3, and a saw-tooth step66made along the cylindrical mounting wall61substantially at a free end67of the cylindrical mounting wall61axially on the side away from the annular reading wall63. In the preferred embodiment, the step66is circumferentially continuous, in the form of an annular ridge, and can interact by snap-fitting with a recess45, or contoured annular groove, made along the collar41about the axis A.

Alternatively, the step66may also be made circumferentially discrete, for example as a plurality of bumps angularly separated from one another by circumferential openings, or circumferential windows.

In the preferred embodiment of the sealing device1of the present invention shown inFIGS. 1 and 2, the step66is made on the outer lateral surface61bof the cylindrical mounting wall61and extends radially outwards from the outer lateral surface61bwhile, accordingly, the recess45is made in the cylindrical inner lateral surface44of the collar41. As the guard6is being press-fitted in the collar41, in a press-fitting direction D, the step66slides along and in contact with the inner lateral surface44, until it reaches the recess45, and is then snap-fitted into the recess45, axially engaging, at least in the direction of removal, the guard6inside the collar41. To prevent the guard6from being axially press-fitted too far into the collar41, even after snap-fitting of the step66in the recess45, the latter has an axial stop end wall46against which, where applicable, the end67of the cylindrical mounting wall61may come into contact, thereby preventing any contact between the annular reading wall63and the phonic wheel51. In any case, to prevent any kind of potential contact between the annular reading wall63and the phonic wheel51, the axial distance between the end67of the cylindrical mounting wall61and the axial stop end wall46is smaller than the axial distance between the annular reading wall63and the phonic wheel51.

The step66slides along the inner lateral surface44substantially freely, if only due to the need to overcome the friction generated by the contact between the step66and the inner lateral surface44and, in the alternative case in which the step66is made as circumferentially discrete, the friction may be reduced in combination, possibly, with the guard6being made of more rigid plastic.

Alternatively, in the preferred embodiment of the present invention of the sealing device1which is an alternative to that just described, indicated by the reference sign1′ inFIGS. 3 and 4, the step66is made on the inner lateral surface61aof the cylindrical mounting wall61and extends radially inwards from the inner lateral surface61awhile, accordingly, the recess45is made in the cylindrical outer lateral surface42of the collar41. As the guard6is being press-fitted in the collar41, the step66slides along and in contact with the outer lateral surface42, until it reaches the recess45, and is then snap-fitted into the recess45, axially engaging the guard6inside the collar41. In this alternative preferred embodiment of the invention, the guard6may never be press-fitted too far into the outside of the collar41, even after snap-fitting of the step66in the recess45, since the snap-fitting occurs substantially concomitantly with the axial contact between the annular reading wall63and the annular end surface43of the collar41.

In this case too, the step66slides along the outer lateral surface42substantially freely, if only due to the need to overcome the friction generated by the contact between the step66and the lateral surface44and, in the alternative case in which the step66is made as circumferentially discrete, the friction may be reduced in combination, possibly, with the guard6being made of more rigid plastic.

Lastly, to ensure the guard6is leak-tight once mounted on the collar41, or to ensure the bearing3is sealed off from the outside and prevent external contaminants (water, dirt, dust, etc.) from entering the bearing3, the sealing device1shown inFIGS. 1 and 2further comprises an annular gasket9arranged inside a respective annular groove9a, which is made in the cylindrical mounting wall61on the same side as the step66at an axial distance L from the step66and has, in section, a substantially trapezoidal shape axially defined by two opposite axial annular edges91and92. The gasket9is made of a thermoplastic elastomer such as TPE, TPS, TPV or the like, and is co-injection-molded inside the groove9a, adhering chemically to the plastic of the guard6, thus making it possible to hold the annular elastomer gasket9in place during press-fitting of the guard6.

In the preferred embodiment of the sealing device1shown inFIGS. 1 and 2, the annular groove9a, in which the elastomer of the annular gasket9is co-injection-molded, is made in the outer lateral surface61bof the cylindrical mounting wall61, and the annular gasket9is arranged inside the groove9a, projecting slightly with respect to the outer lateral surface61bwhile, according to an embodiment not shown, the annular gasket9is arranged inside the groove9asubstantially flush with the lateral surface61bat least at the two axial annular edges91and92, and has a substantially domed shape at the centre of the groove9a, projecting radially outwards from the outer lateral surface61b. When the guard6is press-fitted into the collar41, the step66, sliding along the inner lateral surface44, causes a radial inward flexion of the cylindrical mounting wall61, preventing rubbing of the gasket9from just before the inner lateral surface44substantially until the step66is snap-fitted inside the recess45and thus preserving, thanks to the position of the gasket9at the distance L from the step66, the sealing characteristics of the gasket9.

The distance L is determined as a function of the plastic from which the guard6is made, or the rigidity and/or flexibility thereof, or as a function of the radial height of the step66, which must be such as to allow elastic deformation of the wall61or, also, as a function of the axial dimensions and, above all, radial dimensions of the gasket9: indeed, as stated above, the annular gasket9is arranged inside the groove9asuch that it projects slightly with respect to the outer lateral surface61bbut not beyond the step66and, therefore, during press-fitting, due to the outer lateral surface61bbeing moved elastically away from the cylindrical inner lateral surface44, it is not caught in any way, allowing it to slide freely between the two lateral surfaces61band44. This effect is beneficial also in the case (not shown) in which only the more central part of the gasket9projects with respect to the lateral surface61bby virtue of its being substantially domed radially outwards at the centre of the groove9a.

Once the step66is snap-fitted inside the recess45, the cylindrical mounting wall61returns to its undeformed configuration, radially compressing the gasket9between the cylindrical mounting wall61and the collar41, thereby ensuring the necessary leak-tight seal of the sealing device1.

Alternatively, in the preferred embodiment of the present invention of the sealing device1which is an alternative to that just described, indicated by the reference sign1′ inFIGS. 3 and 4, the annular groove9a, in which the elastomer of the gasket9is co-injection-molded, is made in the inner lateral surface61aof the cylindrical mounting wall61, and the annular gasket9is arranged inside the groove9a, projecting slightly with respect to the inner lateral surface61awhile, according to an embodiment not shown, the annular gasket9is arranged inside the groove9asubstantially flush with the lateral surface61aat least at the two axial annular edges91and92, and has a substantially domed shape at the centre of the groove9a, projecting radially outwards from the inner lateral surface61a. When the guard6is press-fitted into the collar41, the step66, sliding along the outer lateral surface42, causes a radial outward flexion of the cylindrical mounting wall61, preventing rubbing of the gasket9from just before the outer lateral surface42substantially until the step66is snap-fitted inside the recess45and thus preserving, thanks to the position of the gasket9at the distance L from the step66, the sealing characteristics of the gasket9.

Also in this alternative embodiment, the distance L is determined as a function of the plastic from which the guard6is made, or the rigidity and/or flexibility thereof, or as a function of the radial height of the step66, which must be such as to allow elastic deformation of the wall61or, also, as a function of the axial and radial dimensions of the gasket9: indeed, as stated above, the annular gasket9is arranged inside the groove9asuch that it projects slightly with respect to the outer lateral surface61bbut not beyond the step66and, therefore, during press-fitting, due to the inner lateral surface61abeing moved elastically away from the cylindrical outer lateral surface42, it is not caught in any way, allowing it to slide freely between the two lateral surfaces61aand42. This effect is beneficial also in the case (not shown) in which only the more central part of the gasket9projects with respect to the lateral surface61aby virtue of its being substantially domed radially inwards at the centre of the groove9a.

Also in this case, once the step66is snap-fitted inside the recess45, the cylindrical mounting wall61returns to its undeformed configuration, radially compressing the gasket9between the cylindrical mounting wall61and the collar41, thereby ensuring the necessary leak-tight seal of the sealing device1.

The sealing device1and1′ described above, in the preferred embodiments thereof, has undeniable advantages when it comes to the production of the guard6, which may be made completely in a single molding operation, and when it comes to assembly with the bearing3since the guard6may be presented to, and mounted on, the bearing3without the need for any other operation. Above all, the fact that a groove9ais made in the cylindrical mounting wall61, and the material for the gasket9is injected therein, helps keep control of all the geometric dimensions of the sealing device1much to the advantage of performance in terms of sealing and stability. Moreover, in combination, the fact that the groove9aand the related gasket9are on the same side as the step66makes it possible to avoid any damage to the gasket9when the guard6is mounted on the bearing3.

According to the invention, by virtue of the sealing device1, or the sealing device1′, a hub/wheel assembly2like that described above is obtained in which the guard6comprises:a cylindrical mounting wall61, coaxial with the axis A, which is coupled to the collar41of the outer ring4of the bearing3, and has an inner lateral surface61aand an outer lateral surface61b;a saw-tooth step66made along the cylindrical mounting wall61, andan annular gasket9, which is arranged inside a respective annular groove9amade in the wall61on the same side as the step66at an axial distance L from the step66.

In the above hub/wheel assembly2, in the guard6, preferably in combination with the abovementioned features, the saw-tooth step66and the annular gasket9may be arranged radially on the outside of the cylindrical mounting wall61so as to interact, respectively, with a recess45made on the inside of the collar41and a cylindrical inner lateral surface44of the collar41or, alternatively, the saw-tooth step66and the annular gasket9may be arranged radially on the inside of the cylindrical mounting wall61so as to interact, respectively, with a recess45made on the outside of the collar41and a cylindrical outer lateral surface42of the collar41.

In addition to the embodiments of the invention as described above, it is to be understood that there are numerous other variants. It is also to be understood that the embodiments are solely exemplary and do not limit the scope of the invention, its applications, or its possible configurations. On the contrary, although the above description enables those skilled in the art to apply the present invention in at least one exemplary configuration, it is to be understood that numerous variations of the described components may be devised, without thereby departing from the scope of the invention as defined in the appended claims, interpreted literally and/or according to their legal equivalents.