Sealing device for antifriction bearing comprising identifying means

A sealing device for an antifriction bearing includes a fixed support and a rotating support, the sealing device comprising a metal frame designed to be associated with a support of the bearing and a sealing joint, the frame including an annular seat and, secured to the seat, electronic identifying means consisting of a transponder connected on a communication antenna, wherein the antenna has an at least semi-annular or annular shape which is designed to be urged opposite the seat, the identifying means being secured to the seat via an insulating material layer which is interposed between the antenna and the seat so as to provide electromagnetic insulation for the antenna.

CROSS REFERENCE TO RELATED APPLICATION

This application is a National Stage entry of International Application No. PCT/FR06/001209, filed May 29, 2006, the entire specification claims and drawings of which are incorporated herewith by reference.

BACKGROUND

Field

The invention relates to a sealing device for an antifriction bearing comprising a fixed support and a rotating support, as well as such a bearing, in particular a ball bearing, comprising such a device for sealing the bearing space laterally.

Introduction

In the field of antifriction bearings, increasing demand for maintenance and traceability imposes the need for routine access to information relating, in particular, to the production, origin, characteristics and/or operating conditions of a bearing.

For this reason, document WO-A1-02/101675 suggests providing a transponder equipped with an antenna in a housing formed in a ring of a bearing. The transponder, which is capable of recording and transmitting information relating to the bearing, fulfils the aforementioned demands.

However, this embodiment is not entirely satisfactory in that the metal environment of the housing reduces the capability of the transponder to communicate with the detector designed to be positioned remotely. In fact, the propagation of radio waves through metal induces a considerable disruption of the communication signal, which imposes constraints for positioning the transponder and/or positioning the detector at a very short distance from the transponder, or even in contact with the latter in order to ensure the reliability of the communication. Moreover, the creation of the housing in the ring is not satisfactory from the mechanical and economic points of view.

Document WO-A1-2004/072747 describes the possibility of placing a transponder on a sealing joint of a bearing. However, as in the preceding document, the geometry of the communication antenna does not allow for reliable communication.

The invention aims, in particular, to solve the aforementioned problems, in particular by providing a sealing device for an anti-friction bearing that specifically integrates specific identifying means, in order, taking into consideration the severe metallic environment found in the bearings, to improve the reliability of the communication between the identifying means and the detector.

SUMMARY

According to a first aspect, the invention provides a sealing device for an antifriction bearing comprising a fixed support and a rotating support, the sealing device comprising a metal frame designed to be associated with a support of the bearing and a sealing joint, the frame comprising an annular seat and, solidly attached to the seat, electronic identifying means formed by a transponder connected to a communication antenna with an antenna geometry that is at least semi-annular or annular which is arranged to be positioned opposite the seat, the identifying means being solidly attached to the seat by means of a layer of insulating material interposed between the antenna and the seat in order to provide electromagnetic insulation for the antenna.

According to a second aspect, the invention provides an antifriction bearing, in particular a ball bearing, comprising a fixed support, a rotating support and rolling bodies placed between the supports to allow the relative rotation of the supports, the bearing also comprising such a sealing device, the frame being associated with one of the supports in order laterally to seal the bearing space formed between the supports.

Further objectives and advantages of the invention will become apparent from the following description made in reference to the appended drawings.

DETAILED DESCRIPTION

In relation withFIGS. 2 to 4, a ball bearing is described comprising an inner ring1, an outer ring2and balls3placed between the rings so as to allow the relative rotation of the rings. The invention is not limited to this type of bearing, and also relates to any type of antifriction bearing comprising a fixed support and a rotating support. The rolling bodies can also have a non-spherical geometry, for example being shaped as rollers or needles.

The bearing comprises a sealing device which is positioned coaxial to the rings1,2in order laterally to seal the bearing space formed between the rings.FIGS. 2 to 4show only one side of the bearing on which the sealing device is provided, the other side possibly being equipped with a known sealing device or another sealing device according to the invention, identical or different to those shown. In particular, the sealing device can be of a known type integrating a multipolar magnetic encoder15, for example, in order to benefit, in particular, from an angular position signal of the rotating ring in relation to the fixed ring.

The sealing device(s) allow(s) the bearing space in which the balls3are arranged to be insulated from the potentially polluting external environment and from possible leaks of the lubricant contained in the bearing space.

A description is given below of the three embodiments of a sealing device shown inFIGS. 2 to 4, the device comprising a metal frame4associated with a ring1,2of the bearing and a sealing joint. Furthermore, the sealing device comprises electronic identifying means5formed by a transponder6connected to a communication antenna7.

FIG. 1shows such identifying means5formed by an RFID (Radio Frequency Identification) tag which has the particular advantage of being capable of remotely reading and storing the information in the transponder6, formed by an electronic chip.

In the field of antifriction bearings, the information exchanged can relate, in particular to the production of the bearing, its origin, its specific characteristic (operating temperature ranges, maximum speed of rotation, permissible loads, etc.), its state of wear and/or the operating conditions of the bearing or the assembly in which it is integrated. In particular, this information can be used for the purposes of maintenance, traceability or operation of the bearing.

According to the embodiment shown, the identifying means5comprise a metal annular antenna7connected by wires to an electronic chip6. In a variation not shown, the geometry of the antenna7can be at least semi-annular, in particular semi-annular, with the chip6, for example, connected at the central section. The antenna7and the chip6are chosen according to operating constraints, in particular in that relating to communication distances and frequencies.

In a known manner, these kinds of identifying means5are designed for contactless communication with a specific fixed detector (not shown) which can be external to the bearing, or even integrated with the same. The detector ensures reading/writing of the information, the information then being available for use in a system specific to the assembly integrating the bearing or in a system external to the assembly. The identifying means are preferably of the passive type, which is to say that they do not have their own energy source, although active identifying means can also be used.

The frame4of the sealing device is typically made from folded sheet metal and comprises a seat4aon which the identifying means5are solidly attached. In particular, the geometry of the antenna7is arranged to be placed opposite the seat4a, either of the whole seat in the case of an annular antenna7or of a circumferential portion thereof in the case of an at least semi-annular antenna7.

This embodiment provides mechanical support for the identifying means5, which is advantageous considering its fragility, in particular due to the size of its antenna7in relation to its diameter. Indeed, the antenna7is typically formed by a thin ring of electrically conductive material. In particular, the diameter of the antenna7is equal to the median diameter of the seat4a, although it can vary within certain limits if the width of the seat4ais greater than that of the antenna7.

In addition, the invention allows the antenna7to be electromagnetically insulated from the metal frame4in order to reduce losses of reliability of the communication signal in the event of direct contact between the former and a metal part. For this purpose, a layer of electromagnetically insulating material is interposed between the antenna7and the seat4a.

Moreover, the frame4forms a metal mass of less consideration than the ring1,2of the bearing, so that the position of the antenna7at a distance from the rings interferes less with the communication signal. Furthermore, the embodiment according to the invention makes it possible to avoid specific machining of the bearing as well as modifying the general structure of the bearing to integrate the identifying means5.

Finally, the invention makes it possible to combine the following in the frame4of the sealing device:the use of a specific antenna7which, in particular due to its size, allows long-distance communication (typically between 5 and 10 cm) while being mechanically supported by the frame4in order to prevent possible deterioration of the antenna; withelectromagnetic insulation by interposing an insulating material between the frame4and the antenna7.

According to the first embodiment (FIG. 2), the frame4comprises a substantially radial seat4aconnected to an axial seat4bextending towards the inside of the bearing for fitting the frame4onto an inner wall of the outer ring2.

The sealing joint comprises an elastomer element8overmoulded on the free end of the radial seat4a. The elastomer element8, for example made from Viton®, acrylonitrile or a similar material, comprises a free part in frictional contact with one wall of the inner ring1. On particular, stress means formed by an annular spring9are associated with the free part so as to apply an outer lip8aand an inner lip8bof the part to the wall of the inner ring2.

In this embodiment, the elastomer element8is associated with the frame4at a distance from the radial seat4a, so as to leave the outer surface of the latter free. The identifying means5are associated with the free part by means of insulating material, for example by means of a polymer material.

In the embodiment of the invention shown, the identifying means5are overmoulded on the seat by an insulating material10which can be the same as or different from that forming the elastomer element8. Overmoulding10has the advantage of providing mechanical protection for the identifying means5, in particular against possible damaging contact that it might suffer during the operation of the bearing and/or during the communication. As a variation, it is possible to glue the identifying means5with a layer of adhesive insulating material, or to glue previously overmoulded identifying means5.

In the embodiment ofFIG. 2, the identifying means5are substantially arranged in the plane P of the lateral surfaces of each of the rings1,2. In this way, the identifying means5are positioned as close as possible to the outside of the bearing, which improves their accessibility for the purpose of communication from outside the bearing, while providing mechanical protection thereof due to their position inside the space formed between the rings1,2.

According to the second embodiment (FIG. 3), the frame4comprises an outer axial seat4bfor insertion and a radial seat4aarranged inside the bearing space, at a distance from the lateral surface of the rings1,2.

The sealing joint comprises an elastomer element8which is overmoulded on the frame4such as to cover the outer surfaces of the frame4and to have a seal-free part. In particular, the free part comprises two lips, inner8aand outer8brespectively, which are in frictional contact with the inner surfaces of a second frame11which is fitted onto the inner ring1.

In this embodiment, the identifying means5are associated with the elastomer element8, the layer of the latter placed on the radial seat4aforming a layer of insulating material for the antenna7. InFIG. 3, the identifying means5are also overmoulded and glued to the elastomer element8, which increases the electromagnetic insulation in the case of the overmoulding10having insulating properties.

As a variation, the identifying means5can be directly associated with the elastomer element8, for example by gluing. The means can also be overmoulded from the elastomer element8at the same time as the frame4. Due to the elastic properties of the element8, the latter embodiment improves the mechanical protection of the identifying means5, in addition to the electromagnetic insulation it provides.

According to the third embodiment (FIG. 4), the sealing device has the same structure as that inFIG. 3, namely two frames4,11respectively fitted onto the rings1,2so as to form an annular chamber12between them, where the sealing is provided.

The elastomer element8is associated with the inner frame11to be in frictional contact with the outer frame4inside the chamber. However, in this third embodiment, the identifying means5are associated with the outer frame4.

The outer frame4comprises an axial seat4bfor insertion on an inner wall of the inner ring1and a substantially radial outer wall forming the seat4awith which the identifying means5are associated by overmoulding an insulating material10according to the first embodiment.

The outer wall4acomprises an inner axial indentation4a′ in which the identifying means5are arranged in order to be mechanically protected by the annular projections formed around the indentation4a′. In fact, this embodiment limits all direct contact with the identifying means5.

In the embodiments described above, the ring which is solidly attached to the identifying means5can be rotating or fixed, the geometry of the antenna7guaranteeing good communication in both scenarios, while providing optimum mechanical protection of the identifying means against aggressions suffered during the operation of the bearing.

Moreover, the identifying means5are positioned outside the sealing device, which is to say that they are not in direct contact with the inside of the bearing space, which also improves their protection.

Also for the purpose of protection, the embodiment ofFIG. 3can be modified by associating a sealing lip with the outer frame11, the lip being in frictional contact with the inner frame4such as to seal the annular chamber12and therefore the identifying means against the outside of the bearing.