Bearing housing, and bogie for rail vehicles comprising a housing of this kind

A bearing housing including a casing; a rotary bearing with an exterior race mounted inside a bore of the casing, an interior race adapted to be mounted on a shaft and rolling members between the races; and a cap fastened to a front-end face of the shaft, the cap forming an abutment for the interior race on the front face. The bearing housing also comprises a sealing ring mounted in the cap and intended to be clamped axially between the end face of the shaft and the cap.

This application claims priority to French patent application no. 1851902 filed on Mar. 6, 2018, the contents of which are fully incorporated herein by reference.

TECHNOLOGICAL FIELD

The present invention concerns the field of rotary bearings, and in particular those intended to be incorporated in a bearing housing of a rail vehicle bogie.

BACKGROUND

In the field of rail transport, a vehicle such as a carriage generally comprises one or more bogies, each bogie being supported by one or more axles fastened to two wheels. These bogies are connected to bearing housings comprising a rotary bearing designed to provide the pivot connection between the bearing housing and the axle. For example, a classic carriage comprises two bogies, each bogie being supported by two axles. In this case, each bogie comprises four bearing housings each containing a rotary bearing.

A bearing housing generally comprises a cylindrical casing, at least one rotary bearing being inserted in a bore formed in the cylindrical casing. One end of a shaft extends into a rear opening of the casing, a journal extending the shaft end and being arranged in the rotary bearing. The front opening of the casing is closed by a cover.

The rotary bearing generally comprises an exterior race mounted in the bore of the casing, the exterior race being immobilized axially between the cover on the front face and an abutment fastened to the casing on the rear face. The rotary bearing also comprises an interior race mounted on the shaft end journal, the interior race being retained axially between a cap fixed to the journal on the front face and a retaining ring on the rear face against a shoulder of the journal. The exterior race is fixed and the interior race turns, at least one row of rolling members being disposed between the relatively rotatable races.

The cap has an annular general shape and classically comprises an essentially circular plate, provided with a plurality of openings for the passage of retaining screws fixed to the shaft end journal. This plate generally comprises a central bore. The cap also comprises an annular rim extending radially from the periphery of the plate, the rim coming to abut against the interior race of the rotary bearing. The journal and the plate are axially separated from one another, forming an annular open portion closed in the radial direction by the rim.

It is moreover known to provide a hollow shaft defining a central bore in such applications to rail vehicles in order to reduce the weight of the shaft, and therefore the weight of the arrangement in the bearing housing, and thus to reduce the energy consumption of the rail vehicle.

However, in the event of large variations of temperature, the air present in the hollow shaft can condense and create water in liquid form. This water can then come to flow into the open portion that exists between the cap and the shaft end journal.

Moreover, it is classic to carry out an ultrasound inspection of the shaft during a maintenance operation to detect internal defects or cracks. In order to facilitate the transmission of sound energy between an ultrasound probe and the shaft, a coupling medium is injected into the hollow shaft. This coupling medium is generally an oil, for example glycerin, and the quantity injected can be approximately 30 ml. Following the inspection, this oil is found to be collected in the open portion that exists between the cap and the shaft end journal.

Water, oil, and even metal particles can therefore be found collected in the open portion and form internal pollution that cannot be removed without completely dismantling the bearing housing.

When the bearing housing and the axial shaft are in operational mode, shocks and vibrations can induce migration of this internal pollution toward the components inside the bearing housing. This internal pollution can have for consequence accelerated deterioration of the components inside the bearing housing. Water can in particular generate a phenomenon of corrosion notably responsible for a reduction in the quality of the contact between the rolling members and the races of the rotary bearing, and also reduced lubrication performance of the grease introduced into the rotary bearing. This results in a reduction of the quality of the mechanical connection provided in the bearing housing and a reduced service life of the components inside the bearing housing. The risk of breaking, notably in operational mode, is also higher.

In order to alleviate this disadvantage, it is known to provide a through-opening in the lower portion of the bore of the casing in order to evacuate residual liquid water. However, a hole of this kind has the drawback of forming a passage for exterior pollution to the interior of the bearing housing. Moreover, a hole of this kind is not reliable for other types of internal pollution, in particular residual oil following ultrasound inspection.

Accordingly, in the field of rail transport, regular maintenance operations are carried out during which the components of the bearing housing are demounted and then cleaned and inspected. If necessary, the grease can be drained from the rotary housing in order to replace it. Finally, the components of the bearing housing are reassembled. However, maintenance operations of this kind are costly, relatively lengthy and necessitate frequency immobilization of the rail vehicle.

SUMMARY

The present invention aims to remedy these disadvantages.

The present invention more particularly aims to provide a bearing housing offering reliable operation, good reliability over time, and no necessity for a multiplicity of maintenance operations.

The invention concerns a bearing housing to receive a shaft of an axle, comprising a cylindrical casing, a rotary bearing, and a cap.

The cylindrical casing is provided with a bore with an opening on the rear face able to receive an end of the shaft and an opening on the front face closed by the cover.

The rotary bearing is provided with a fixed exterior race mounted in the bore of the casing, a turning interior race adapted to be mounted on an exterior cylindrical surface of the shaft end, and at least one row of rolling members disposed between the races.

The cap is of annular general shape and provided with a radial plate, with a plurality of openings through which pass dedicated retaining screws to be fixed to an end face at the shaft end, and an annular rim extending axially from the exterior periphery of the plate, the rim coming to abut against the interior race of the rotary bearing on the front face.

According to the invention, the bearing housing also comprises a sealing ring mounted in the cap, the sealing ring being arranged radially in the annular rim of the cap and being intended to be clamped axially between the end face at the shaft end and the plate of the cap.

According to other advantageous but not obligatory features of a bearing housing according to the invention, separately or in combination:

The bearing housing comprises a retaining ring mounted on the shaft end, axially between a shoulder of the shaft and the interior race of the rotary bearing on the rear face.

The bearing housing comprises an abutment fastened to the casing on the rear face, the exterior race of the rotary bearing being immobilized axially between the cover and the abutment.

The abutment comprises a plurality of openings through which pass retaining screws fixed to the casing on the rear face.

The cover comprises a plurality of openings through which pass retaining screws fixed to the casing on the front face.

The rolling members are cylindrical rollers.

The rolling members are regularly spaced by a cage.

The rotary bearing comprises two rows of rolling members.

The exterior race is formed in one piece.

The interior race is formed of two parts, each supporting a row of rolling members, a spacer being disposed axially between the parts.

The rotary bearing comprises a first sealing means disposed between the exterior race and the interior race at the front axial end of the bearing and a second sealing means disposed between the exterior race and the interior race at the rear axial end of the bearing.

The plate of the cap comprises a central bore.

The sealing ring comprises a central bore.

The inside diameters of the central bores of the sealing ring and the plate of the cap are substantially equal.

The sealing ring is solid, comprising no bores.

The sealing ring comprises a plurality of openings axially facing the openings of the plate of the cap, the openings of the sealing ring and of the cap having passed through them dedicated retaining screws that are to be fixed to the end face at the shaft end.

The sealing ring is made of polymer material.

The sealing ring is made of butadiene-acrylonitrile copolymer, also known as “nitrile rubber”.

The invention also concerns a rail vehicle bogie comprising at least one axle provided with a shaft and at least one bearing housing in accordance with any of the foregoing embodiments mounted on one end of the shaft.

The shaft is advantageously hollow with a bore.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, a bearing housing1is intended to be fastened to a bogie of a rail vehicle in such a manner as to support via a pivot connection an axle fastened to the wheels of the rail vehicle.

For the remainder of the description, the terms “front” and “rear” are defined for the position of the bearing housing relative to the bogie. A front position is one with a face of the housing situated axially toward the exterior of the bogie, while a rear position is one with a face of the housing situated toward the interior of the bogie.

The bearing housing1comprises two fixing ends1-1and1-2enabling the housing to be fixed to a rail vehicle bogie (not shown). This fixing can be affected in the classic manner, each end1-1and1-2being fixed to one end of a rod of a damper coupled to a suspension (not shown).

The axle comprises a hollow shaft2provided with a cylindrical central bore2-1. The hollow shaft2is extended at its end by a journal2-2.

The housing1comprises a cylindrical casing3with a cylindrical central bore4with axis X4. The casing3comprises an opening5of the bore4on the rear face in such a manner as to receive the shaft2. The casing3comprises an opening6of the bore4on the front face, the front opening6being closed by a cover7.

To provide the pivot connection between the axle and the bearing housing1, the housing1comprises a rotary bearing8with axis X8with an exterior race9, an interior race10, and rolling members11disposed radially between the races9,10. In the normal operating mode of the bearing housing1, the axes X4and X8coincide. In this embodiment, the rotary bearing8comprises two rows of tapered rollers as the rolling members11. The rolling members are advantageously held regularly spaced by cages. A different bearing can be used without departing from the scope of the invention, for example with only one or more than two rows of rolling members, with other types of rolling members such as cylindrical rollers, needles or balls.

The rotary bearing8advantageously comprises a first sealing flange17-1disposed between the exterior race9and the interior race10at the front axial end of the bearing8and a second sealing flange17-2disposed between the exterior race9and the interior race10at the rear axial end of the bearing8. The rolling space between the two races9,10in which the rolling members11are housed is therefore isolated from the exterior environment and can contain a lubricant fluid, for example grease.

The exterior race9is mounted in the cylindrical bore4formed in the casing3. The exterior race9is retained axially on one side by an abutment12and on the other by the cover7. The abutment12is fastened to a rear end surface of the casing3by a plurality of retaining screws18and the cover7is fastened to a front-end surface of the casing3by a plurality of retaining screws19. The exterior race9is fixed and is fastened to the casing3.

The interior ring10is fitted over an exterior cylindrical surface of the journal2-2of the shaft2. In this embodiment, the interior race10is made up of two parts10-1and10-2, a spacer10-3being disposed axially between the parts. The interior race10is held axially between a retaining ring13and a cap14.

The retaining ring13is mounted on the journal2-2of the shaft2, axially between a shoulder2-3of the shaft and the interior race10of the rotary bearing8on the rear face.

The cap14is of annular general shape and provided with a radial plate14-1, with a cylindrical bore14-2and a plurality of openings14-3through which pass retaining screws15fixed to a front-end face2-4of the journal end2-2of the shaft2. The cap14is also provided with an annular rim14-4extending axially from the exterior periphery of the plate14-1. The rim14-4comes to abut against the interior race11of the rotary bearing8on the front face.

According to the invention, the bearing housing1also comprises a sealing ring16shown inFIG. 3.

The sealing ring16is annular with an essentially cylindrical body. The sealing ring16is mounted in the cap14, the sealing ring16being arranged radially in the annular rim14-4of the cap14.

The sealing ring16comprises a plurality of openings16-1axially facing the openings14-3of the plate14-1of the cap14. The openings16-1,14-3of the sealing ring16and the cap14, respectively, have passed through them the retaining screws15fixed to the end face2-4of the shaft2. The sealing ring16is arranged axially between the end face2-4of the shaft2and the plate14-1of the cap14.

The sealing ring16further comprises a cylindrical central bore16-2. The bore16-2of the sealing ring16advantageously has an inside diameter substantially equal to that of the bore14-3of the plate14-1of the cap14.

The sealing ring16is made of polymer material. In a particularly advantageous manner the sealing ring16is made of butadiene-acrylonitrile copolymer, also known as “nitrile rubber”.

Thanks to the invention, all of the open portion between the cap14and the end2-2of the shaft2is open. No interior pollution, such as water, oil or metal particles, can find itself trapped between these elements.

During a maintenance operation, only the cover7on the front face of the casing3has to be demounted to clean the interior of the bearing housing1, all the internal zones of the housing1being easily accessible from the front opening6.

Moreover, the cap14and the sealing ring16both being provided with a central bore14-2and16-2, respectively, it is possible to clean the cylindrical bore2-1of the hollow shaft2.

Thanks to complete cleaning of the bearing housing1according to the invention during a maintenance operation, the risks of condensation and the risks of pollution of the moving parts, such as the rings9,10and the rolling members11of the rotary bearing8, are avoided. The quality of the contact between the surfaces in contact and the properties of the grease are then preserved. The result of this is an improvement in the quality of the mechanical connection provided in the bearing housing and an increased service life of the internal components of the bearing housing. The risk of breakage, notably in the operating mode, is also lower.

According to an alternative that is not shown, the sealing ring16is solid, comprising no bores. The sealing ring therefore enables closing of the bore2-1of the hollow shaft2and prevention of any entry of internal pollution from the hollow shaft to the interior volume of the bearing housing1.

Moreover, some or all of the technical features of the various embodiments may be combined with one another. Thus, the bearing housing can be adapted in terms of cost, performance and simplicity of implementation.