EP0446139B1 - Acoustic alarm with aeration channel, particularly for motor vehicles - Google Patents

Description

The present invention relates to audible warning devices, in particular for motor vehicles, of the type comprising a hollow housing closed in leaktight manner by a membrane and carrying an electromagnetic vibration generator provided, inside the housing, with a coil carcass carrying a coil.

Such an alarm is described in document FR-A-2 069 792.

By design, the horn will heat up during operation.

In fact, in the volume of the housing closed by the membrane, an increase in temperature, due in particular to the electromagnetic generator, causes an increase in the internal pressure.

It is for this reason that the above-mentioned document has provided a breathing hole facilitating exchanges with the outside and making it possible to balance the external and internal pressures.

This hole can be calibrated and form by itself means of protection against the penetration of water.

As a variant, a filter can be added to the hole protecting the alarm against the ingress of water.

This hole is made by means of a part which is formed by injection of plastic material into the housing, with protection by a sheath or a tube.

As a variant, the skirt of the housing is extended towards the outside by a tube capped by a protective cap (see also FR-A-2,517,451).

All these provisions complicate the manufacture of the housing and in some cases they are not optimal because the holes can become blocked.

In addition, this leads to protrusions which can be inconvenient for the installation of the horn.

In addition, before mounting, this increases the risk of damage to the horn by improper handling.

Document FR-A-2 279 187 provides, for the protection of the breathing hole of the housing, an external cover which communicates with the external atmosphere through a labyrinth orifice.

Document FR-A-1 335 125 provides an orifice which opens into the air in a place protected from external spraying by a wall forming a screen.

The object of the present invention is to overcome the drawbacks of known devices and therefore to create, in a simple and economical manner, a breathing system of simple and robust manufacture, of flawless operation and little fear of false manipulations, while providing d 'other advantages.

According to the invention an alarm of the above-mentioned type is characterized in that the carcass has, for communication with the hole in the housing, at least one duct of smaller section to allow the passage of air, said duct being provided with means to prevent water from entering the interior of the alarm.

Thanks to the invention, without discomfort for the establishment of the alarm, it takes advantage of the existing parts and the manufacture of the housing is simplified, the hole which it presents need not be precise. In addition the realization of the conduit is easy especially when the carcass is made of plastic.

In addition there is no risk of damaging or losing any cap before mounting the alarm, or of damaging the breathing system thereof during wrong handling.

The housing and the carcass can be produced in different production units.

Advantageously, the duct is formed by means of fixing ears, which the carcass presents.

In all cases, tests have shown that protection of the housing hole is not necessary, the increase in pressure in the horn is enough to drive out any deposits at the inlet of the duct.

In addition, it is easy to install a filter, either at the inlet of the duct, or at the outlet, or at any location.

• la figure 1 est une vue en coupe axiale d'un avertisseur sonore selon l'invention, du type basse fréquence ;
• la figure 2 est une vue en coupe axiale analogue à la figure 1, mais pour un avertisseur sonore, du type haute fréquence ;
• la figure 3 est une vue selon la flèche F de la figure 2 du boîtier équipé seulement de sa carcasse avec sa lame porte-contact ;
• la figure 4 est une vue selon la flèche G de la figure 2, reprenant à plus grande échelle les détails repérés par l'encart C de la figure 2 ;
• la figure 5 est une vue en coupe selon la ligne A-A de la figure 4 ;
• la figure 6 est une vue en coupe selon la ligne B-A de la figure 4.

The description which follows illustrates the invention with reference to the appended drawings in which:

• Figure 1 is an axial sectional view of an audible warning device according to the invention, of the low frequency type;
• Figure 2 is an axial sectional view similar to Figure 1, but for a horn, of the high frequency type;
• Figure 3 is a view along arrow F of Figure 2 of the housing equipped only with its carcass with its contact carrier blade;
• Figure 4 is a view along arrow G of Figure 2, taking on a larger scale the details identified by the insert C of Figure 2;
• Figure 5 is a sectional view along line AA of Figure 4;
• FIG. 6 is a sectional view along the line BA in FIG. 4.

In FIGS. 1 and 2, the horn for motor vehicles, also known as an electroacoustic signaling horn, comprises a hollow housing 1 for attachment to a fixed support delimiting a cavity closed in leaktight manner by a membrane 50.

The housing 1 carries, inside its cavity, an electromagnetic vibration generator with an excitation coil 20 carried by a coil carcass 3 while being wound thereon.

The carcass 3 is centrally hollow by being mounted on a fixed core 21. A plunger core 22 is allowed to penetrate inside the carcass to approach the fixed core 21.

The plunger core 22 is integral with the membrane 50 and forms with it a mobile assembly.

We see at 23 one of the supply terminals of the coil 20 and at 24 a conductive contact-carrying blade with at 25 an air gap adjustment screw.

As a reminder, it will be recalled that the electromagnetic vibration generator forms an excitation device which imparts movement to the membrane so that the volume of the cavity delimited by the housing 1 varies.

In FIG. 1, the movable membrane 50 - plunger core 22 assembly is interposed between a metal receiving plate 41 and a flange 10 of the housing with the addition of a seal.

The plate 41 forms a cover for a hollow roof 40, made of plastic, provided with a cavity in communication with a central recess of the platinum and a projecting mouthpiece in the open air.

The pavilion 40 has a shoulder opening, while the plate 41 secures the housing 1 and the membrane 50, thanks to its folded edge on the membrane 50 and the housing 1.

The plate is glued to the roof, as described in document FR-A-2 335 903 and comes into contact with the shoulder opening of the roof.

In FIG. 2, the collar 10 is linked to the membrane 50 by a ring 61 set on the collar 10.

The membrane 50 is integral with a disc 60, disposed beyond the ring 61, for the formation of a resonator.

In the case of the horn of Figure 1, the movement of the membrane varies the volume defined by the membrane 50 and the plate 41 for producing a sound.

In the case of an alarm of the high frequency type of FIG. 2, the plunger core 22 secured to the membrane 50 strikes the fixed core 21 for propagation of a sound wave amplified by the disc 60.

In these figures, the housing 1 is annular being made of stamped sheet metal and comprises, in addition to the flange 10, forming a radial rim directed opposite the axis of the assembly, a first tubular portion delimited by an axial skirt 11 connecting to the flange 10, an annular transverse wall 12 connecting to the skirt 11 and carrying a second annular portion of smaller diameter delimited by an axial skirt 13, closed by a transverse bottom 14.

The coil 20 is housed with its carcass 3 inside the skirt 13, the carcass 3 bears on the bottom 14 open centrally for the passage of a threaded part 15 secured to the fixed core 21 of larger diameter.

The core 21 is supported on the bottom 14 inside the housing 1 and serves as an annular centering device for the carcass 3, while the part 15 is used for fixing the housing 1 to an elastic tongue (not visible) integral with a fixed part of the vehicle.

The carcass 3 has for this a main part 31, on the one hand, centrally hollow to cooperate in centering with the core 21 and, on the other hand, with a U-shaped section for mounting the coil 20.

The hollow housing 1 has a hole 6 for connecting the interior of the housing 1 with the exterior and preventing the movement of the membrane 50 from being altered by an overpressure or a depression prevailing in the housing.

According to the invention the carcass 3 has, for communication with the hole 6 of the housing 1, at least one cylindrical duct 2 of smaller diameter to allow the passage of air to the interior of the housing 1, said duct 2 being provided with means to prevent the penetration of water inside the alarm.

More precisely, it is the wall 12 of the housing 1 which is drilled to form the hole in an area clear of that carrying the supply terminals 23, in the vicinity of the latter and of one of the attachment points of the coil. as described below.

To do this, the carcass 3, advantageously made of plastic, has two fixing lugs 32 and 33 secured to a radial extension 35 extending in excess thickness inside the housing 1 in contact with the wall 12 and connecting to the end of the main part 31 opposite the bottom 14 by a connection leave 37.

The extension 35 with its ears 32, 33 forms a fork with two radial arms carrying the ears which are not identical to each other. Both are used to fix the carcass 3 to the housing 1, but the ear 32 is also used for fixing the blade 24, which extends radially over a great height on either side of the axis of symmetry and radially beyond the carcass 3 (FIG. 3 ), while the ear 33 has a protuberance 36 or protuberance.

It is thanks to this protuberance 36 that the conduit 2 is made, which is here opposite the hole 6, the center of the hole being disposed on the axis of the conduit 2.

This conduit 2 is connected to a recess 7 formed in the face of the protuberance 36 adjacent to the wall 12, while the other face of the protuberance is hollowed out for housing a filter 4 provided with pores and preventing the penetration of the and moisture in the housing 1.

The conduit 2 here extends parallel to the axis of the assembly and therefore opens into the recess 7 and into the filter 4 held in place, for example, by high frequency welding, gluing, or simple pinching.

The recess 7 has a diameter greater than that of the hole 6 and serves as a trap for impurities.

An O-ring 5 is mounted in the recess 7, being placed between the carcass 3 and the wall 12 in order to seal between these two components and to prevent corrosion.

Of course the filter 4 can be placed in any location of the duct 2, for example at the entrance of the latter into the cavity 7.

As a variant, it is possible to insert it into the thickness of the protuberance 36 in the middle of the duct.

In all cases in the event of overpressure or depression inside the housing, breathing is possible through the hole 6 and the conduit 2 without altering the sound of the alarm.

Tests have shown that the increase in pressure in the horn was enough to drive the possible deposits at entry 7 of conduit 2.

It will be appreciated that the carcass 3 is subjected to vibrations, owing to the fact that it is penetrated by the core 22 and that it carries the vibrating blade 24, so that this is also favorable for unclogging the conduit 2.

Note that the arrangement is robust because it does not protrude externally relative to the housing which is simplified.

Note that the arrangement in the vicinity of the ear 33 is favorable.

Indeed, good contact takes place between the carcass 3 and the wall 12 due to the presence of the fixing member 66, here a rivet or alternatively a bolt, passing through the ear 33, by means of a part 62 mounted engaged in a hole in the ear 32 and having a shoulder part in contact with the external face of the wall 12.

This piece 62 blocks the head of the rivet thanks to a lip favorable to a good seal.

The end of the rivet 66 is crimped in contact with a metal distribution washer 63 bearing on the face of the ear 33 furthest from the wall 12.

It is on the rivets 66 that the supply terminals 23 are welded.

As will be understood and it emerges from the description, the hole 6 does not need to be calibrated with precision and the conduit 2 can be produced with precision independently of the housing, in a unit of different production.

Of course, the present invention is not limited to the example of embodiment described, in particular the duct 2 can be placed at any location on the carcass, in particular in the radial extension 35 proper, the hole 6 being moved accordingly.

Similarly, the carcass may have an additional ear specific for the conduit, and the radial extension 35 may be devoid of fixing ears.

In all cases the production by molding of the plastic carcass lends itself to many forms.

The presence of the filter 50 avoiding the penetration of water is not obligatory, the duct 2, the length of which depends in particular on the various applications, which can be calibrated to let air pass but not water and thus form by itself means to prevent the penetration of water inside the horn. Similarly, the recess 7 can be deleted.

This duct can open into a coaxial duct of larger diameter for mounting, for example, the filter 4 which is then closer to the wall 12.

The hole 6 can be offset radially with respect to the duct 2 and be connected to the latter by means of a recess similar to the recess 7 extended radially as a result.

The conduit 2 can be inclined relative to the axis of the assembly.

The carcass may have tubing entering the hole in the housing.

The carcass may have an axial rim opposite the skirt 11 in which the duct 2 is formed.

Finally, the duct 2, instead of having a cylindrical bore, may have a section of any shape, said section having a size smaller than that of the hole 6.

Claims (10)

1. Acoustic alarm, in particular for use in motor vehicles, comprising a hollow casing (1) tightly sealed by a membrane (50) and having an electromagnetic oscillator provided in the interior of said casing (1) with a solenoid plunger (22) and a coil case (3) integral to said casing (1) and having an exciting coil (20), said case (3) being hollow to receive said solenoid plunger (22), wherein said casing (1) is provided with a hole (6) connecting the interior of said casing (1) to its exterior to allow the acoustic alarm to breathe, characterised in that for connection with said hole (6), said case (3) has at least one duct (2) with a smaller cross-section than said hole (6) to allow the flow of air into the interior of said casing (1), said duct being provided with means to prevent water from penetrating into the interior of said casing (1) of said acoustic alarm.
2. Alarm according to Claim 1, characterised in that the duct (2) is arranged to face the hole (6) in the casing (1).
3. Alarm according to Claim 1, characterised in that the duct (2) is shifted radially in relation to the hole (6) in the casing (1).
4. Alarm according to any of the preceding claims, characterised in that the inlet to the duct (2) feeds into a recess (7) with a larger cross-section.
5. Alarm according to Claim 4, characterised in that the recess (7) is provided with a seal (5) positioned between the case (3) and a wall (12) of the casing (1) to ensure a tight seal between these two components.
6. Alarm according to any of the preceding claims, characterised in that the duct (2) is connected to a filter (4), which is provided with pores to prevent water penetration and humidity in the casing (1).
7. Alarm according to one of Claims 1 to 5, characterised in that the duct (2) is calibrated to provide means to prevent water from penetrating into the interior of said acoustic alarm.
8. Alarm according to any of the preceding claims, wherein the coil case (3) is made of plastic material, characterised in that the duct (2) is formed in a lug of said case (3).
9. Alarm according to Claim 8, characterised in that the duct (2) is formed by means of a projection (36) of a fastening lug (33) provided to secure the case (3) to the casing (1).
10. Alarm according to one of Claims 1 to 7, wherein the coil case (3) is made of plastic material and, being excessively thick in the interior of the casing (1), has a radial extension (35), characterised in that the duct (2) is formed in said radial extension (35).

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