FR3082137A1 - METHOD FOR MANUFACTURING A VEHICLE EQUIPMENT PART, EQUIPMENT PART AND ASSOCIATED MOUNTING METHOD - Google Patents

Abstract

The invention relates to a method of manufacturing a piece of equipment (10) for a motor vehicle, comprising the following steps: - provision of a compressible seal (12) in a mold (24), the seal sealing (12) internally delimiting a passage channel (16) of a fluid and / or of equipment; - Formation in the mold (24) of a wall (14) around the seal (12), the wall (14) comprising at least a first layer of foam (20), the first layer of foam (20) being attached to the outer periphery of the seal (12) without adhesive.

Description

Method of manufacturing a piece of equipment of a motor vehicle, piece of equipment and associated mounting method

The present invention relates to a method of manufacturing a piece of equipment for a motor vehicle.

The piece of equipment is in particular intended to form all or part of a soundproofing component of a motor vehicle, in particular of a motor vehicle apron disposed between the engine compartment and the passenger compartment of the vehicle.

The soundproofing component is intended to solve the acoustic problems which arise in a substantially enclosed space, such as the passenger compartment of the motor vehicle (apron, floor, roof, etc.), in the vicinity of noise sources such as an engine. .

In general, in the low frequency range, the acoustic waves generated by the aforementioned noise sources undergo a "damping" by materials in the form of single or double sheets (prestressed sandwich) having a viscoelastic behavior or by acoustic attenuation of a porous and elastic mass-spring system.

Within the meaning of the present invention, a soundproofing assembly provides “insulation” when it prevents the entry of medium and high frequency acoustic waves into the soundproofed space, essentially by reflection of the waves towards the noise sources or outside the soundproofed space.

A set of soundproofing works by "acoustic absorption" (in the medium and high frequency domain) when the energy of the acoustic waves dissipates in an absorbent material.

A high-performance soundproofing system must work at the same time ensuring good insulation and good absorption. To characterize the performance of such an assembly, we use the notion of NR noise reduction index which takes into account the two notions of insulation and absorption. This index can be calculated by the following equation:

NR (dB) = TL - 10log (S / A) where TL is the sound reduction index (hereinafter the reduction index) reflecting the insulation. The higher this index, the better the insulation

A is the equivalent absorption area. The higher A, the better the absorption. S is the surface of the whole.

To provide good sound insulation, it is known to use one or more layers of absorbent material to form the soundproofing component and to place it between the noise source and the passenger compartment.

In some cases, it is necessary to drill this soundproofing component in order to pass fluids and / or components. For example, it is necessary to pass the components of the air conditioning unit arranged in the passenger compartment through the bulkhead in order in particular to supply outside air to the air conditioning group.

A seal is then placed around the drilled openings in order to limit acoustic and fluid leaks. It is known to stick such a seal on the air conditioning unit.

However, this operation being usually carried out manually, it is costly in production time and imprecise. This imprecision has the effect of causing dispersion of positioning of the seal in the vehicle. To overcome this it is necessary to create a mounting clearance between the soundproofing and the seal of the air conditioner block which leads to acoustic and fluidic leaks.

An object of the invention is to provide a more precise method of manufacturing a piece of equipment, in order to guarantee improved acoustic properties, while being less expensive.

To this end, the invention relates to a method of manufacturing a piece of equipment of a motor vehicle comprising the following steps:

- provision of a compressible seal in a mold, the seal internally delimiting a passage channel for a fluid and / or equipment;

- Formation in the mold of a wall around the seal, the wall comprising at least a first layer of foam, the first layer of foam being fixed to the outer periphery of the seal without adhesive.

According to embodiments, the method according to the invention comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:

- the seal is a closed contour ring;

- the seal is made of a foam having semi-closed cells on the surface;

the wall comprises a second layer of foam, the second layer of foam being formed on the first layer of foam, the second layer of foam having a density different from the density of the first layer of foam;

- The first layer of foam has a density between 60 kg / m ³ and 150 kg / m ³ and the second layer of foam has a density between 40 kg / m ³ and 55 kg / m ³ ;

- The formation of the at least one layer of foam is carried out by injecting a precursor capable of foaming, the precursor crosslinking in the mold in order to form the at least one layer of foam;

- A region of the seal protrudes from a surface of the wall parallel to the axis-A of the passage channel;

- The wall has a thickness between 8 mm and 30 mm.

The invention also relates to a piece of equipment of a motor vehicle comprising a compressible seal internally delimiting a passage channel for a fluid and / or equipment and a wall disposed around the seal. sealing, the wall comprising at least a first layer of foam, the first layer of foam being fixed to the outer periphery of the seal without adhesive.

According to one embodiment, the piece of equipment comprises the following characteristic: the motor vehicle comprises an engine and a passenger compartment, the part being an apron of the motor vehicle suitable for being disposed between the engine and the passenger compartment.

The invention also relates to a method of mounting a piece of equipment as defined above, comprising a step of applying the wall to a metallic surface, the metallic surface delimiting an opening, the passage channel opening into the opening, the seal applying to the periphery of the opening on the metal surface.

The invention will be better understood on reading the description which follows, given solely by way of example, and made with reference to the appended drawings, in which:

- Figure 1 is a front view of a piece of equipment of a motor vehicle according to the invention;

- Figure 2 is a sectional view along the plane II of Figure 1 of the part of Figure 1;

- Figure 3 is a sectional view of the part of Figure 1 in a mold during manufacture according to the method according to the invention; and

- Figure 4 is a sectional view of the part of Figure 1 mounted in the motor vehicle.

In all that follows, the orientations are generally the usual orientations of a motor vehicle. The terms "above", "on >>," below >>, "under", "upper", "lower" are understood relatively, with respect to the reference surface of the motor vehicle, opposite of which the piece is placed.

A piece of equipment 10 of a motor vehicle according to the invention is illustrated in FIG. 1.

Part 10 is intended to be mounted inside a motor vehicle, in particular to form a sound-absorbing assembly.

In particular, the part 10 is intended to be disposed between the engine and the passenger compartment of the motor vehicle. The part 10 is then an apron of the motor vehicle configured to absorb at least part of the noise coming from the engine towards the passenger compartment.

The part 10 comprises a seal 12 and a wall 14 arranged around the seal 12.

The seal 12 internally delimits a passage channel 16 of a fluid and / or of equipment, which extends through the wall 14 and opens out on either side of the latter.

The seal 12 is configured to seal at the passage channel 16.

In particular, the seal 12 is configured to prevent leakage of the fluid flowing in the passage channel 16. The fluid is, for example, air from outside which will supply the air conditioning unit of the motor vehicle.

The seal 12 also prevents sound leakage on either side of the part 10 due to the drilling of the part 10.

As shown in Figure 2, the passage channel 16 extends along a main axis A-A '.

In the example of FIG. 1, the passage channel 16 has a section in a plane orthogonal to the axis A-A ’of rectangular shape.

As a variant, the passage channel 16 has a section in a plane orthogonal to the axis A-A ’of oblong or circular shape.

Advantageously, the section of the passage channel 16 in a plane orthogonal to the axis AA ′ has a surface of between 50 cm ² and 700 cm ² .

As shown in Figure 1, the seal 12 is a closed contour ring.

The seal 12 advantageously has a width in a direction orthogonal to the axis A-A ’between 5 mm and 30 mm.

The seal 12 advantageously has a thickness along the axis A-A ’between 16 mm and 60 mm.

The seal 12 advantageously has a thickness at least twice as thick as the thickness of the wall 14. As visible in FIG. 2, at rest, a region 18 of the seal 12 protrudes from a surface of the wall 14 parallel to the axis A-A 'of the passage channel 16.

In particular, the projecting height of the region 18 of the seal 12 parallel to the axis A-A ’is between 8 mm and 30 mm.

The seal 12 is formed from a foam. Advantageously, the seal 12 comprises ethylene-propylene-diene monomer (EPDM).

In particular, the seal 12 is obtained from split foam.

The seal 12 then has semi-closed cells on the surface.

The seal 12 is advantageously compressible. The seal 12 is thus able to deform under the action of an external force.

The wall 14 is configured to provide soundproofing, in particular between the engine compartment and the passenger compartment of the motor vehicle.

The wall 14 advantageously has a thickness along the axis A-A 'of between 8 mm and 30 mm.

The wall 14 comprises at least a first layer of foam 20.

In an advantageous embodiment, the wall 14 further comprises a second layer of foam 22 disposed on the first layer of foam 20.

As shown in Figure 2, the first layer of foam 20 is directly attached to the outer periphery of the seal 12, without interposition of an adhesive.

The first layer of foam 20 advantageously has a thickness along the axis A-A 'of between 4 mm and 20 mm.

The first layer of foam 20 is produced on the basis of an elastic porous or even viscoelastic foam.

This foam is advantageously open cell.

The first layer of foam 20 is advantageously made of polyurethane.

The density of the first foam layer 20 is advantageously between 60 kg / m ³ and 150 kg / m ³ .

The first layer of foam 20 is porous and has a porosity adapted to have a resistivity to the passage of air advantageously between 10,000 N.m ' ⁴ .s and 90,000 Nm / s.

Resistance to the passage of air or its resistivity is measured by the method described in the thesis Measurement of parameters characterizing a porous medium. Experimental study of the acoustic behavior of foam at low frequencies., Michel HENRY, defended on October 3, 1997 at the University of Le Mans.

As shown in FIG. 2, the second layer of foam 22 extends over part of the first layer of foam 20.

In particular, the second layer of foam 22 is formed completely away from the periphery of the seal 12.

Alternatively, the second layer of foam 22 extends over the entire upper surface of the first layer of foam 20 and is attached to the outer periphery of the seal 12 without adhesive.

The second layer of foam 22 advantageously has a thickness along the axis A-A 'of between 4 mm and 20 mm.

The second layer of foam 22 is produced on the basis of an elastic porous or even viscoelastic foam.

This foam is advantageously open cell.

The second layer of foam 22 is advantageously made of polyurethane.

The second layer of foam 22 has a density different from the density of the first layer of foam 20.

In particular, the second layer of foam 22 has a density less than the density of the first layer of foam 20.

The density of the second layer of foam 22 is advantageously between 90 kg / m ³ and 100 kg / m ³ .

The second layer of foam 22 is porous and has a porosity adapted to present a resistance to the passage of air advantageously between 300 N.rri ³ .s and 6000 N.mts.

Thus, the layers of foam 20, 22 together form a bipermeable complex with distinct air passage resistances.

A method according to the invention for manufacturing the piece of equipment 10 will now be described.

Initially, the seal 12 is placed in a mold 24.

Then, as shown in FIG. 3, the wall 14 is formed around the seal 12 in the mold 24.

Here, the mold 24 includes only one element defining the reception surface. The reception surface advantageously has reliefs, in particular hollows and bumps depending on the final configuration of the piece of equipment 10.

As a variant, the mold 24 comprises two half-molds which are movable relative to one another between an open configuration and a closed configuration. In the closed configuration, the half-molds define a cavity with the receiving surface of shape conjugated with the part 10.

Advantageously, the region 18 of the seal 12 then projects from a surface of the wall 14 parallel to the axis A-A ’of the passage channel 16 of the seal 12.

In particular, the first layer of foam 20 is formed around the seal 12.

Advantageously, the first foam layer 20 is formed by injecting a precursor capable of foaming. Then, the precursor crosslinks in the mold 24 in order to form the first layer of foam 20 around the seal 12 and in contact with the latter.

Advantageously, the foam in formation of the first layer of foam 20 penetrates into the semi-closed cells of the surface of the seal 12, ensuring the robust fixing of the first layer of foam 20 on the seal 12 and l sealing between them.

The first layer of foam 20 is thus securely and tightly fixed to the outer periphery of the seal 12, without the need to use an adhesive.

Then, the second layer of foam 22 is formed on the first layer of foam 20.

Advantageously, the formation of the second layer of foam 22 is carried out by injecting a precursor capable of foaming on the first layer of foam 20. Then, the precursor crosslinks in the mold 24 in order to form the second layer of foam 22 on the first layer of foam 20.

Thanks to the characteristics described above, the method according to the invention allows better control of manufacturing tolerances. Indeed, the wall 14 being overmolded on the seal 12, there is no play due to a poor arrangement of the seal 12 by an operator.

Acoustic leaks are thus greatly reduced and the seal 12 is not oversized to ensure a good seal.

The process therefore saves time, since the operator does not have to manually place and glue the seal on the wall.

The method also allows an additional cost saving, due to the absence of glue necessary for fixing the joint to the wall.

The piece of equipment 10 mounted in the motor vehicle is illustrated in FIG. 3.

The wall 14 is in contact with a metal surface 26.

In particular, the second layer of foam 22 is in contact with the metal surface 26.

The metal surface 26 is for example a structural sheet metal of the motor vehicle, in particular a shield separating the passenger compartment from the engine compartment.

As visible in FIG. 4, the surface 26 delimits an opening 28.

The passage channel 16 opens into the opening 28.

The seal 12 is applied to the periphery of the opening 28 on the metal surface 26.

The seal 12 is here compressed by the metal surface 26. Thus, no region of the seal 12 projects from a surface of the wall 12 parallel to the axis A-A 'of the passage channel 16 .

The wall 14 is also in contact with a nozzle 30 of a pipe.

The end piece 30 is for example made of plastic.

The end piece 30 is placed opposite the metal surface 26 relative to the wall 14.

The end piece 30 is for example an air inlet of the air conditioning circuit of the motor vehicle.

As visible in FIG. 4, the end piece 30 defines an opening 32.

The passage channel 16 opens into the opening 32.

The seal 12 is applied to the periphery of the opening 32 on the metal end piece 30.

A method according to the invention for mounting the piece of equipment 10 will now be described.

Initially, a piece of equipment 10 is provided.

The method includes a step of applying the wall 14 to the metal surface 26.

The passage channel 16 then opens into the opening 28.

The seal 12 is applied to the periphery of the opening 28 on the metal surface 26.

Advantageously, the method further comprises a step of applying the end piece 30 to the wall 14.

The passage channel 16 then opens into the opening 32.

The seal 12 is applied to the periphery of the opening 32 on the metal end piece 30.

The mounting of the piece of equipment 10 in the motor vehicle is therefore easy and rapid, further ensuring adequate sealing of the air conditioning circuit.

Claims (11)

1. - Method for manufacturing a piece (10) of equipment of a motor vehicle comprising the following steps: - provision of a seal (12) compressible in a mold (24), the seal (12) internally delimiting a passage channel (16) of a fluid and / or equipment; - Formation in the mold (24) of a wall (14) around the seal (12), the wall (14) comprising at least a first layer of foam (20), the first layer of foam (20) being attached to the outer periphery of the seal (12) without adhesive. 2. - The manufacturing method according to claim 1, wherein the seal (12) is a closed contour ring. 3. - The manufacturing method according to claim 1 or 2, wherein the seal (12) is formed of a foam having semifermed cells on the surface. 4. - Manufacturing process according to any one of the preceding claims, wherein the wall (14) comprises a second layer of foam (22), the second layer of foam (22) being formed on the first layer of foam (20 ), the second layer of foam (22) having a density different from the density of the first layer of foam (20). 5. - The manufacturing method according to claim 4, wherein the first layer of foam (20) has a density between 60 kg / m ³ and 150 kg / m ³ and the second layer of foam (22) has a density included between 40 kg / m ³ and 55 kg / m ³ . 6. - Manufacturing process according to any one of the preceding claims, in which the formation of the at least one layer of foam (20, 22) is carried out by the injection of a precursor capable of foaming, the crosslinking precursor in the mold (24) to form at least one layer of foam (20,22). 7. - Manufacturing process according to any one of the preceding claims, in which a region (18) of the seal (12) projects from a surface of the wall (14) parallel to the axis (A- A ') of the passage channel (16). 8. - Manufacturing method according to any one of the preceding claims, wherein the wall (14) has a thickness between 8 mm and 30 mm. 9. - Piece (10) of equipment of a motor vehicle comprising: - a compressible seal (12) internally delimiting a passage channel (16) of a fluid and / or of equipment; - a wall (14) disposed around the seal (12), the wall (14) comprising at least a first layer of foam (20), the first layer of foam (20) being fixed to the outer periphery of the seal sealing (12) without adhesive. 10. - Piece of equipment according to claim 9, wherein the motor vehicle comprises an engine and a passenger compartment, the part (10) being an apron of the motor vehicle suitable for being disposed between the engine and the passenger compartment. 11. - A method of mounting a piece of equipment according to claim 9 or 10 in a motor vehicle comprising a step of applying the wall (14) on a metal surface (24), the metal surface (24) delimiting an opening (26), the passage channel (16) opening into the opening (26), the seal (12) applying to the periphery of the opening (26) on the metal surface (24) .