WO2006097251A1

WO2006097251A1 - Blow-molded, sound-absorbing engine cover with a surface decoration

Info

Publication number: WO2006097251A1
Application number: PCT/EP2006/002248
Authority: WO
Inventors: Jörg PAULI; Eduard Brück
Original assignee: Carcoustics Tech Center Gmbh
Priority date: 2005-03-15
Filing date: 2006-03-10
Publication date: 2006-09-21
Also published as: DE202005004259U1

Abstract

The invention relates to an engine cover (1'), which is made of plastic, absorbs airborne sound, has a surface decoration, and which is provided for an internal combustion engine of a motor vehicle. This engine cover comprises fastening means and/or recesses for fastening the engine cover to an internal combustion engine. In order to provide an engine cover (1') of this type in a cost-effective manner and, optionally, to be able to recycle without any problems, the invention provides that the engine cover is formed from a blow-molded part. The wall section (9) of the blow-molded part facing away from the internal combustion engine is provided with the surface decoration, which is formed from at least one decorative part (5') that is back-blown with or joined to the blow-molded part. The wall section (7) of the blow-molded part facing the internal combustion engine has a number of box-like and/or cup-like hollow chambers (8). At least a number of hollow chambers (8) belong to a common air space enclosed in the blow-molded part.

Description

Blow molded, sound absorbing engine cover with surface decoration

The invention relates to a motor-produced, airborne sound absorbing engine cover with Oberflächendekor for an internal combustion engine of a motor vehicle, with fastening means and / or recesses for fixing the engine cover to an internal combustion engine.

Motor vehicles, especially diesel vehicles are becoming increasingly popular today. equipped with sound-absorbing engine covers, which regularly have a design function as molded parts.

Conventional engine covers are provided with elaborate absorber materials. In general, these consist of foams or nonwoven materials, which are adapted in a separate process the shape of the engine cover and the contour of the motor to be covered. For example, from DE 199 04 986 Al a sound-absorbing engine cover is known which has a plurality of cover layers of foam material, wherein in a certain area between two cover layers, a filling layer of foam material is arranged. The cover is secured to a plastic shell functioning as a design cover by ultrasonic welding. The manufacturing cost of such engine cover are relatively high. In addition, a single-grade recycling Such engine covers feasible only with great effort.

Sound absorbers manufactured in extrusion blow molding technology, which are arranged below the engine for sound-insulating encapsulation of the engine compartment, are known (see EP 0 775 354 B1). However, the surface condition of these known sound absorbers does not regularly meet the requirements placed on the surface finish of engine covers, which also have a design function.

The present invention has for its object to provide a sound-absorbing engine cover with design function, which can be relatively inexpensive to manufacture and easy to recycle.

According to the invention this object is achieved by an engine cover with the features of claim 1.

The motor cover according to the invention is essentially characterized in that it is formed from a blow molding, the combustion engine facing away from the wall portion is provided with the Oberflächendekor and facing the engine wall portion facing a plurality box and / or cup-like hollow chambers, wherein at least a plurality of the hollow chambers belongs to a common, enclosed in the blow molding airspace, and wherein the Oberflächendekor is formed from at least one of the blow molded part behind the blown or connected decorative part.

The blow molding of the engine cover according to the invention can be cost-effectively in the so-called "one-shot The decorative part can be manufactured as a prefabricated insert with a surface finish that meets the highest design requirements.The rear-blown decorative part can be made of the same material (plastic type) as the blow molded part, so that the complete engine cover can easily be recycled sorted In particular, the decorative part can be a separately molded plastic part with a shaped and / or color-formed visible side.

If desired, as a decorative part and a shaped sheet metal or a metal foil can be chosen with design character and back-blown with an extruded thermoplastic plastic tube or two thermoplastic films in a corresponding mold, so that the back of the decorative part cohesively with the a variety of box and / or cup-shaped hollow chambers having blow molding is connected.

An advantageous embodiment of the motor cover according to the invention is that the hollow chambers of the blow molding at least partially with a free-flowing material such as, for example, Quartz sand, barium sulfate and / or magnetite are filled. As a result, the soundproofing effect of the engine cover is increased.

In the sound-absorbing engine cover according to the invention, additional functions can advantageously also be integrated. For example, in the blow molding, an air duct, a liquid container and / or a fluid line may be integrated. The air or liquid passed through the motor cover can thus be heated to save energy. The liquid container may in particular be a windscreen wiper water container.

A particularly high temperature resistance can be achieved for the engine cover according to the invention if the wall section of the blow molding part facing the internal combustion engine is covered at least in regions with a microperforated aluminum foil. By using a microperforated aluminum foil, a relatively broadband sound absorption can also be achieved.

A further advantageous embodiment of the engine cover according to the invention consists in that structures for the positive attachment of plug-in coupling elements are formed in the wall section of the blow molding part facing the internal combustion engine. As a result, a simple and quick installation of the engine cover is made possible. Preferably, the plug-in coupling elements are configured vibration decoupling.

Further preferred and advantageous embodiments of the engine cover according to the invention are specified in the subclaims.

The invention will be explained in more detail with reference to a drawing illustrating several embodiments. In a schematic representation:

1 is a perspective plan view of the visible side of an engine cover according to the invention. FIG. 2 shows a perspective bottom view of the side of a motor cover according to the invention facing the motor to be covered; FIG.

3 is a partial sectional view through a cylinder head of an internal combustion engine with a cylinder head cover and an engine cover according to the invention;

4 is a partial sectional view similar to FIG. 3, but showing a variant of the engine cover; and

Fig. 5 is a partial sectional view similar to Figures 3 and 4, showing a further modified embodiment of an engine cover according to the invention.

The engine cover 1 shown in Figures 1 and 2 serves as a sound-absorbing panel for a portion of an internal combustion engine, in particular diesel engine.

The engine cover 1 is attached to the top of the engine. For this purpose, it has formed recesses 2 with openings or recesses 3, in which the heads of mounting screws (not shown) are received sunk. In addition, claw-shaped fastening straps 4 are integrally formed on the engine cover 1.

The engine cover 1 is formed from a blow molding, the combustion engine facing away from the wall portion is provided with a Oberflächendekor. The surface Decor consists of a separately prefabricated decorative part 5, which has a form and color-shaped visible side as a molded part.

The decorative part 5 of the motor cover shown in FIG. 1 has a region marked by hatching, which comprises a section 5.1 with a plurality of convex curvatures, an adjoining substantially flat section 5.2 and an adjoining bevelled side section 5.3. The hatched area (5.1 to 5.3) can be formed, for example, from a through-colored, silver-colored plastic film.

The decorative part 5 has a further region 5.4, which is shown without hatching and made of a different colored plastic than the hatched area. For example, a solid-colored, silver-colored plastic film, which is used for the range 5.1 to 5.3, are back-injected with black or dark plastic, such that in addition to a shape-shaped, silver-colored area, a black or dark-colored, shaped area 5.4 is generated.

The various regions of the decorative part 5 can be made of the same type of plastic, for example of polyamide or preferably of polypropylene.

The prefabricated decorative part 5 is inserted as a depositor in a blow molding tool (not shown) and back-blown with a hollow body formed from thermoplastic material. The hollow body (blow-molded body) can be produced in the so-called "twin-sheet process" from two thermoplastic plastic films or by extrusion blow molding from a tubular preform, wherein the preform or the plastic films in the plasticized state between two movable halves of a blow molding tool (not shown) squeezed, compressed with compressed air and pressed against the inner wall of the closed tool, whereby the compressed air is supplied by means of a blowing mandrel, which protrudes into the preform or between the plastic films.

The one tool half has a recess in which the prefabricated decorative part 5 is inserted as a depositor and with suitable holding means; e.g. is fixed with a suction device, before the start and during the blowing process. The other half of the blow mold has a mold structure comprising a plurality of box or cup-like depressions for forming correspondingly shaped hollow chambers in the blow molding.

Fig. 2 shows the wall portion 7 of the blow molding of an engine cover 1 according to the invention, which faces a motor to be covered. It can be seen that the box or cup-like hollow chambers 8 are grouped differently sized and in different numbers. Furthermore, it can be seen that a part of the hollow chambers 8 is arranged offset from one another. Each hollow chamber 8 has in the embodiment shown in Fig. 2 has a substantially planar bottom portion 8.1 and transverse thereto chamber walls 8.2, which are also formed substantially planar (see also Figures 3 to 5). The different size of the hollow chambers 8 results inter alia in that their base area is different in size; and additionally or alternatively also in that their depth or the distance of the hollow-chamber bottom 8.1 to the wall section 9 of the blow-molded part is dimensioned differently.

The closed, oscillatory hollow chamber bottom 8.1 acts as a plate resonator (plate absorber). The geometric and thus acoustic design of the hollow chambers 8 is done specifically for the engine type, for which the engine cover 1 is determined.

Fig. 3 shows a section of a cylinder head 10 of an internal combustion engine in a sectional view. In the cylinder head 10, two camshafts 11 are mounted, which serve for the actuation of intake and exhaust valves (not shown). The camshafts 11 are covered by shell-like portions 12 of a cylinder head cover 13, which rests on seals 14 on a flat surface of the cylinder head 10 and is bolted thereto by (not shown) screws.

In order to largely prevent the emission of engine noise, in particular originating from the valve train, a sound-absorbing engine cover 1 'according to the invention is provided which engages over the cylinder head cover 13 and rests against the cylinder head 10 via a circumferential sealing ring 15 which engages around its edge.

For fixing the engine cover 1 'on the cylinder head 10, at least one stud 16 is provided in this embodiment, which is in a corresponding threaded bore 17 is screwed into the cylinder head 10 and has an outer threaded portion 18. This threaded portion 18 extends through a sleeve 19, which passes through a vibration-isolating rubber grommet 20, which in turn engages around a recess 3 in the engine cover V in a form-fitting manner. On the threaded portion 18 finally a cap nut 21 is screwed. The engine cover V is thus detachably fixed to the cylinder head 10.

In the exemplary embodiment shown in FIG. 3, the engine cover 1 ^r has a decorative part 5 ', on the visible side of which a surface relief is formed. The surface relief is indicated here by way of example by ribs 22 which extend parallel to one another in two regions of the decorative part 5 '.

The decorative part 5 'may be an injection molded part made of plastic or else a shaped sheet metal, in particular aluminum sheet. If the decorative part is made of aluminum, it is advantageous if an engaging, used as a decorative part insert is provided on its side facing the blow molding with an adhesive layer. Further, on the blow molding part facing side of a decorative part 5 'made of metal, in particular aluminum, preferably positive-locking elements are provided to ensure a reliable connection of the decorative part 5' with the blow-molded part.

The decorative part 5 'is materially or positively back-blown with a blow molding, which acts as a sound absorber. The two wall sections 7, 9 of the sound absorber are connected to each other, in two edge regions 23, 24 by integral transition and at the transverse edges (not shown). by welding. The above-mentioned Hohlkarranern 8 containing wall portion 7 has a significantly smaller wall thickness than the decorative part 5 'facing wall portion 9. The hollow chambers 8 are open to the wall portion 9 on one side. At least a majority of the hollow chambers 8 forms a common air space 25 enclosed in the blow molded part.

In the region of the hollow chambers 8 point-like or line-shaped welds 26 are formed between the chamber walls 8.2 of the wall portion 7 and the wall portion 9. Some of the hollow chambers 8 are formed so that their chamber walls 8.2 at substantially the same height or depth are partially welded to the decorative part 5 'adjacent wall portion 9 and partially free aufrag directed to this wall portion 9, leaving an air gap 27 between the End face of the chamber wall 8.2 and the wall section. 9

The hollow chambers 8 are spaced from the engine or cylinder head cover 13, so that between the closed, oscillatable Hohlkämmerboden 8.1 and the engine an air space is present.

The exemplary embodiment illustrated in FIG. 4 differs from the exemplary embodiment according to FIG. 3 in particular in that the wall section 7 of the sound absorber facing the internal combustion engine is covered at least in regions with a perforated, preferably micro-perforated aluminum foil 28. The perforated aluminum foil 28 may extend as shown, to the edges 23, 24 of the blow molding (sound absorber) and at the edges 23, 24, this enclosing, be folded. In addition, the perforated aluminum foil 28 held by the rubber grommet 20. An adhesion of the aluminum foil 28 with the blow molding is not required. The aluminum foil 28 has a sufficient dimensional stability and is shaped so that it is at least partially spaced both to the engine or cylinder head cover 13 and to the hollow chambers 8 in order to leave an air space on both sides.

The holes of the microperforated aluminum foil 28 have a diameter which is in the range of 0.05 to 1.5 mm, preferably in the range of 0.05 and 1 mm. The hole area ratio is, for example, in the range of 3 to 15%, preferably in the range of 3 to 10%.

Furthermore, an embodiment variant of the engine cover 1 'according to the invention is outlined in FIG. 4, in which the hollow chambers 8 of the blow molding part are at least partially provided with a free-flowing material 29, such as a blower, to increase the soundproofing effect. Quartz sand, barium sulfate or magnetite are filled. Alternatively or additionally, one or more other cavity regions of the blow molding, in particular planar cavity regions, may be filled with corresponding free-flowing material 29.

In the exemplary embodiment illustrated in FIG. 5, the decorative part 5 ^r 'only covers the blow-molded part in regions. As shown, in the two wall sections 7, 9 of the blow molded part substantially concurrent, overlapping crease lines 30 can be embossed. The bending lines 30 are formed film-hinged, so that the blow-molded part has hingedly interconnected portions 31, 32, on each of which hollow chambers 8 are formed. The section 32 of the blow molding leaves to pivot, for example, for purposes of inspection or maintenance of the engine, in particular pivot upwards.

In Fig. 5 is further outlined that the hollow chambers 8 can be at least partially formed as a hole absorber. The hole absorber is based on the principle of the Helmholz resonator, which is an air-spring system. In this case, a relatively small opening 8.3 is formed in the hollow floor 8.1, which is a neck-like constriction. The air in the opening (constriction) 8.3 forms quasi the mass and the volume of air in the hollow chamber 8, the spring of the resonator.

The motor cover V 'shown in FIG. 5 differs from the exemplary embodiments shown in FIGS. 3 and 5 further in that structures for the positive attachment of plug-in coupling elements 16' are formed in the wall section 7 of the blow molding part. The hollow chamber 8 'has an undercut recess 33, which serves for the positive reception of a spherical head 34 of a bolt 16' bolted to the cylinder head 10. The wall of the hollow chamber 8 'is sufficiently flexible in the region of the indentation 33, so that the hollow chamber 8' acts as a vibration-decoupling plug-in coupling element.

The invention is not limited in its execution to the embodiments described above. Rather, various modifications are conceivable that make use of the disclosed in the appended claims invention even with different design. Thus, in the blow molding (sound absorber) also advantageously at least one air duct, a liquid container and / or at least one liquid be integrated. Furthermore, the features of the engine cover according to the invention shown in the figures can also be combined with each other in different ways.

Claims

PA TENT TO SP RÜ CHE

1. Sound-absorbing, engineered plastic cover (1, 1 ', V') with Oberflächendekor for an internal combustion engine of a motor vehicle, with fastening means and / or recesses (3) for fixing the engine cover to an internal combustion engine, characterized in that it consists of a blow molding is, the combustion engine facing away from the wall portion (9) is provided with the Oberflächendekor and facing the engine wall portion (7) a plurality box and / or cup-like hollow chambers (8, 8 ^f ), wherein at least a plurality of the hollow chambers (8) belongs to a common, enclosed in the blow molding airspace, and wherein the Oberflächendekor of at least one with the blow molding behind-blown or connected decorative part (5, 5 ', 5 ") is formed.

2. Engine cover according to claim 1, characterized in that the decorative part (5, 5 ', 5' ') is a shaped sheet metal or a metal foil.

3. Engine cover according to claim 1, characterized in that the decorative part (5, 5 ', 5'') is a respect to the blow-molded part differently colored plastic part.

4. Engine cover according to one of claims 1 to 3, d a d u r c h e c e n e c e s in that the decorative part (5, 5 ', 5' ') is a prefabricated molded part.

5. Engine cover according to one of claims 1 to 4, d a d u r c h e k e n e c i n e s in that the decorative part (5 '') covers the blow molded part only partially.

6. Engine cover according to one of claims 1 to 5, d a d e r c h e c e n e c e s in that at least one air duct is integrated in the blow molded part.

7. Engine cover according to one of claims 1 to 6, in that a blown molding at least one liquid container and / or at least one liquid line is integrated in the blow molding.

8. Engine cover according to one of claims 1 to 7, d a d u r c h e c e n e c e in that the hollow chambers (8) have a different size and / or height.

9. Engine cover according to one of claims 1 to 8, characterized in that the internal combustion engine facing wall portion (7) of the blow molding at least partially covered with a perforated, preferably micro-perforated aluminum foil (28).

10. Engine cover according to one of claims 1 to 9, d a d e r c h e c e in n e c e s that structures for the positive attachment of plug-in coupling elements (16 ') are formed in the combustion engine facing wall portion (7) of the blow molding.

11. Engine cover. according to one of claims 1 to 10, in that a vibration-decoupling plug-in coupling elements (8 ') or vibration-decoupling fastening means are arranged on the wall section (7) of the blow molding part facing the combustion engine.

12. The engine cover according to claim 1, wherein the wall section facing the engine and the wall section facing away from the engine are provided with an engine cover

(9) of the blow molding at the edge in one piece into each other.

13. Engine cover according to one of claims 1 to 12, d a d e r c h e c e n e c i n e in that the blow molded part is formed from two thermoplastic films which are welded together edge in the finished blow molded part.

14. Engine cover according to one of claims 1 to 13, characterized in that the hollow chambers (8) of the blow molding are at least partially filled with a free-flowing material (29).

15. An engine cover according to one of claims 1 to 14, characterized in that the hollow chambers (8) are designed as plate resonators and / or as Helmholz resonators.