The field of the present invention is that of starters for thermal engines for motor vehicles.

According to a known design, a contactor of a starter of a thermal engine, in particular of a motor vehicle, comprises a cylindrical housing in which there is placed an annular coil which generates a magnetic field under the effect of an electrical current which passes through it. According to the polarisation of the coil, the magnetic field thus created exerts a force on a mobile core which is cylindrical and at least partly magnetic. The mobile core is fitted in an interior space which is delimited by the cylindrical housing, such as to be able to slide there according to axial translation, driving with it a mobile shaft, in order to close or open an electrical circuit which is connected to a supply circuit of the electric motor of the starter. This opening/closure of the electrical circuit is carried out in an area of connection contained in a cavity in the contactor, this cavity being separated form the interior space by a fixed core.

A disadvantage of these contactors consists in the vulnerability of their components when faced with the aggressions of the exterior environment, and particularly when faced with humidity. Thus, the water or sprayed water which manages to penetrate into the contactor can give rise to an electrical contact between one of the electrical terminals arranged in the cavity comprising the area of connection and the housing of the contactor. This electrical contact can then create a short-circuit of the battery to which this electrical terminal is connected electrically, this short-circuit being able to give rise to a thermal incident.

This disadvantage is all the more significant for starter contactors used in humid geographical areas which can have damaged road infrastructures, as well as for starter contactors of off-road vehicles which can be used regularly in rough and in particular humid environments. In order to improve the operation of these contactors, it is already known to put into place devices for sealing between the starter contactor and the environment on the exterior of this contactor.

It is thus known to place sealing devices between the area of connection and the environment on the exterior of the contactor, in order to ensure sealing between this exterior environment and the starter contactor.

However, the movements of translation of the mobile core generate a piston effect when the core emerges from the housing, giving rise to aspiration of the air from the exterior and interior environment of the starter contactor, and thus at the same time dust and water present in this air. This dust and water can therefore penetrate into the interior space of the contactor, and, during subsequent activation of the contactor, can reach the cavity which contains the area of connection. The water can then migrate and reach the area of connection, and finally give rise to the same difficulties as those described above. The sealing devices which are put into place at present are therefore not sufficient.

The present invention comes within this context, and its objective is to propose a device which makes it possible to ensure sealing between the interior space of the contactor and the cavity of this contactor which contains the area of connection.

The subject of the invention is thus a starter contactor comprising a housing which extends along an axis, and delimits at least one interior space, at least one coil accommodated in this interior space, at least one fixed core through which there passes a shaft which is mobile in translation in the direction of the axis, and at least one cavity comprising an area of electrical connection, the said cavity being separated from the interior space by the fixed core. This starter contactor comprises at least one sealing device which ensures sealing between the interior space of the starter contactor and the cavity comprising the area of connection.

This sealing device which ensures the sealing between the interior space of the starter contactor and the cavity comprising the area of connection is known hereinafter as the “first sealing device”.

The assembly of the elements of the contactor is thus contained in the housing, this housing being closed by a cover with at least two orifices through which at least two electrical terminals pass.

This contactor can have at least one second sealing device which ensures sealing between an electrical terminal of the area of connection and the cover which closes the housing. This second sealing device can for example be placed around the electrical terminal, at the orifice by means of which this electrical terminal passes through the cover.

Advantageously, the contactor can have two sealing devices, placed respectively on the periphery of each of the two electrical terminals, at each of the orifices by means of which these electrical terminals pass through the cover.

Optionally, this contactor can also comprise a third sealing device ensuring sealing between the housing of the contactor and the cover. This third sealing device can for example be placed on the periphery of the cover.

Optionally, this contactor can also comprise a fourth sealing device ensuring sealing between the interior space of the starter contactor and the cavity comprising the area of connection. This fourth sealing device can for example be placed between the fixed core and the housing.

According to a variant embodiment of the present invention, the second, third and fourth sealing devices can be O-ring seals.

According to another variant embodiment of the present invention, the second, third and fourth sealing devices can be form seals, which for example are rectangular or oblong.

According to a variant embodiment, the third and the fourth sealing devices are formed from a single sealing device which ensures sealing between the fixed core and the cover. This sealing device thus makes it possible to insulate the cavity comprising the area of connection both against the interior space and the exterior environment of the contactor. This sealing device can be an O-ring seal or a form seal, which for example is rectangular or oblong. This device can be accommodated in an axial recess in the cover, and it can be compressed against an axially normal flat surface of the fixed core. The axial depth of this recess is selected such as to retain the device in position when the contactor is not in the fitted state. In particular, the device is inserted in the recess by at least 50% of its axial length in the fitted state.

It is understood here that the cavity which contains the area of connection is thus completely sealed against the air which surrounds it, whether this area is on the exterior of the contactor, or present in the housing where the coil of the contactor extends.

According to one embodiment, the first sealing device can be placed in the cavity which contains the area of connection.

According to a first embodiment, the contactor has a receptacle for integration of the first sealing device, arranged on the fixed core.

According to a second embodiment of the present invention, the contactor has a receptacle for integration of the first sealing device, arranged on the mobile shaft.

According to the first embodiment of the present invention, the first sealing device is integral with the integration receptacle arranged in the fixed core, this first sealing device being in sliding contact with the mobile shaft. In this case, the first sealing device is fixed relative to the housing when the mobile shaft is translated.

According to the second embodiment of the present invention, the first sealing device is integral with the integration receptacle arranged in the mobile core, this first sealing device being in sliding contact with the fixed core. In this other case, the first sealing device is mobile at the same time as the mobile shaft, when the latter is translated in the fixed core.

According to an embodiment of the present invention, the first sealing device is retained in position in an integration receptacle by means of a support washer. This support washer can for example have a conical cross-section, seen on a cross-section formed on a plane which passes through its central axis.

The mobile shaft of the contactor according to the present invention can have at least one first stop against which the support washer is placed. The first stop can be integral with the mobile shaft. The fixed core of the contactor according to the present invention for its part can have at least one second stop against which the support washer is placed.

According to a characteristic of the present invention, the first sealing device is placed in the cavity which contains the area of connection.

According to an embodiment of the present invention, the first sealing device can be a lip seal.

According to another embodiment of the present invention, the first sealing device can be a self-lubricated seal.

According to another embodiment of the present invention, the first sealing device can be an O-ring seal.

According to another aspect of the invention, the sealing device which ensures the sealing between the interior space of the starter contactor and the cavity comprising the area of connection can comprise a seal and a sealing ring.

The sealing ring can be placed between the seal and the mobile shaft.

The seal can be an O-ring seal. The seal can be made of peroxidised EPDM, or from a material selected from amongst EPDM, NBR, FKM, ACM.

The sealing ring can be a dynamic sealing ring. The ring can be made of PTFE. In addition to the PTFE, the ring can comprise bronze and/or carbon (PTFE filled with bronze or PTFE filled with carbon). The sealing ring makes it possible to prevent the wear by exfoliation which is observed during a to-and-fro motion of the mobile shaft when a seal is directly in contact with the mobile shaft. The wear by exfoliation would make the system non-sealed over a period of time.

The sealing ring can have a cylindrical surface which is in sliding contact with the mobile shaft. Facing the mobile shaft, the ring can have a cavity which makes it possible to establish a pressure force of the seal on the mobile shaft which is different according to its direction of displacement.

According to another aspect of the invention, when the sealing device comprises the seal and the sealing ring as well as the support washer, the support washer can come into contact only with the sealing ring. The seal is not clamped axially in the receptacle of the fixed core. The support washer can have a flat surface facing the sealing device.

According to another aspect of the invention, the second stop against which the support washer abuts can be a notch in the fixed core. The second stop can be situated radially beyond the sealing device.

According to another aspect of the invention, the sealing ring can be thin or thick. According to the application, the ring is thin if its radial dimension is at least twice as small as that of the O-ring seal in the compressed state, i.e. in position in the contactor. It is thick if its radial dimension is substantially equal to that of the seal in the compressed state.

The sealing ring can comprise axial rims to retain the seal in position.

The present invention also relates to a starter of a thermal engine comprising at least one contactor according to the present invention.

