GB2479766A - Flexible sound absorbing cover for a noise-generating container - Google Patents

Abstract

A sound absorbing cover 20, for a container (10) such as an oil-pan of an internal combustion engine, comprises: a resilient outer layer 24, which may be made from ethylene propylene terpolymer rubber; and an inner layer 20 of foam material, such as polyeurethane foam. The outer layer 24 incorporates attachment means, preferably in the form of circular or keyhole shaped holes 30, to enable the cover 20 to be firmly attached to the container (10). The container (10) may include a plurality of projections, such as spherical studs 12, which engage with holes 30 in a readily releasable manner. In a preferred embodiment, the outer layer 24 has a plurality of edge or corner areas 28 which are not covered with the inner foam layer 20. An attachment hole 30 may be located at each of these edge or corner areas 28.

Description

Sound Absorbing Cover The present invention relates to sound absorbing covers, and in particular to sound absorbing jackets for containers, e.g. the oilpans or sumps provided for use in automotive engines.

In automotive engines, especially diesel engines, noise radiated from the oilpan makes a large contribution to the overall sound level emitted by the powertrain.

One previous proposal for use as an oilpan absorber was a material combining wood fibres with FUR foam and covered with PET fleece. This was unsuitable for use in an engine space and was relatively expensive.

A disadvantage of existing sound absorbers is that they need to be attached to the engine with steel brackets. The installation of the absorbers is a time-consuming process and requires the use of additional heavy components. Since removing the absorbers would also be a time-consuming process, they are frequently left in place during routine servicing operations such as changing the oil in the oilpan. This requires access to the oil plug which is covered by the absorber. This means the absorbers become impregnated with oil during the servicing operation which decreases their sound-absorbing capacity and which also increases the risk of a thermal incident.

Aspects of the present invention seek to overcome or at least reduce one or more of the above problems.

According to a first aspect of the present invention, there is provided a sound-absorbing cover for a container comprising a resilient outer layer and an inner layer of foam material, the outer layer incorporating attachment means whereby the cover can be attached firmly to the container.

The advantage of the resilience of the outer layer is that, by stretching it to engage the attachment means, the inner foam layer is tightly held against the container. The outer layer also serves to reflect some of the noise back into the foam layer.

The attachment means are preferably readily releasable so that the absorber can easily be released and removed by a mechanic for a servicing, repair or replacement operation. This means that the absorber does not become contaminated with oil during such operations; accordingly the absorber retains its integrity and does not become a thermal incident hazard.

According to a second aspect of the present invention, there is provided a container having a cover according to the first aspect.

According to a third aspect of the invention, there is provided an engine with an oilpan constituting a container in accordance with the second aspect.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 is a bottom perspective view of an oilpan sound absorbing cover in accordance with an embodiment of the present invention; Figure 2 is a similar view to Figure 1 but from the opposite side of the cover; Figure 3 is a cross-sectional view of an oil pan provided with the cover of Figures 1 and 2; Figure 4 is an enlarged cross-sectional view of part of the sound absorbing cover of Figures 1 to 3; Figure 5 shows an enlarged view of a hole used as part of attachment means for the cover of Figures 1 to 4; and Figure 6 to 8 show alternative attachment means in modifications of Figure 5.

Referring to the drawings, an automotive engine includes an oilpan or sump 10, Figure 3 as part of its lubrication and/or transmission systems. To reduce the noise reaching the environment from the engine, and in particular its powertrain, the oilpan is provided with a sound absorbing cover or jacket 20. The cover is attached to the oilpan by means of spherical studs 12 projecting from the oilpan and connected thereto by narrow shaft portions 18. Only one of the studs 12 is shown in Figure 1. The studs and their shaft portions are bolted to walls 14, 16 of the oilpan.

As shown in Figure 4, cover 20 comprises a layer 22 of polyurethane (PUR) foam sandwiched over a substantial part of its area between an outer layer or skin 24 comprising Ethylene Propylene Terpolymer Rubber (EPDM rubber) and a relatively thin inner layer or coating 26.

Foam layer 22 has a thickness in the range 4 to 20mm and a density in the range 60-l2Og/dm3. Outer layer 24 is preferably made of reinforced EPDM rubber cloth having a thickness in the range of 2-3mm.

The cover is preferably made in a moulding process.

Outer layer 24 is cut to shape and through holes 30 are stamped or cut in corner areas 28. The outer layer is then inserted as an inner layer into a suitably shaped moulding tool where it is held by a vacuum. Polyurethane foam is then moulded or cast over the layer 24 and the two layers are firmly attached to each other. A relatively thin layer 26 is then applied as an in-mould coating (INC) to serve to seal off the exposed surface of the foam layer 22. The moulding tool is configured so that some or all of the corner areas 28 of the outer layer 24 are not covered with the foam layer. This leaves the holes 30 unobstructed. The direction of noise from the oilpan, when the cover is in use, is shown at 36.

Figure 5 shows an enlarged view of one of the holes 30. It is shaped like a keyhole with a larger lower region 32, which is large enough to pass over a spherical stud 12, and a smaller upper region 34 which can fit over a shaft portion 18 but through which a spherical stud cannot pass.

To prepare the cover 20 for attachment to the oilpan 10, one end of the cover is passed beneath the oilpan so that it is generally in the configuration shown in Figure 3. One or more of the holes 30, e.g. those shown in Figure 1, are then placed over respective studs 12 and the cover is moved down slightly so that shaft portions 18 enter narrow regions 34 to engage the cover with the oil pan. One or more holes 30 on the other side of the oilpan 10, e.g. in Figure 2, are then similarly attached.

The relative sizes of the cover and the oilpan, the relative positions of the holes 30 and the studs 12, and the degree of resilience of the cover, in particular its outer layer 24, are selected so that the attachment of the second two holes requires a pulling force sufficient to hold the cover 20, and in particular the foam layer 22, tightly against the oilpan. Thus the cover 20 is effectively strapped to the oilpan 10. To remove the cover 20 for access to the oilpan 10, the process is simply reversed.

The above described arrangement has numerous advantages. Cover 20 is relatively easy and cheap to manufacture. It is easily attached manually to the oilpan without the need of securing brackets to hold it there and without the need for special tools to install it.

Attachment of a hole to a stud requires the use of only one hand. In addition, it is securely retained in place against unintentional release due to vibrations etc and yet can be easily detached manually and removed away from the olipan when required. Since it is a quick and easy operation to detach and remove the cover, it is no trouble for a mechanic requiring access to the oilpan to do this. With existing covers, mechanics requiring access often only detach the cover partially, which hinders access, can damage the cover, and can lead to unwanted oil impregnation of the cover.

The layered structure of the cover, particularly the rubber outer layer 24, assists in reflecting some of the noise back into the oilpan. The resilience of layer 24 further contributes to the sound-proofing in that it holds foam layer 22 in close contact with the surface of the oilpan (i.e. with zero gap) to limit noises emanating from the oilpan surface.

The in mould coating layer 26 serves to prevent oil and dirt being sucked up by the foam layer 22.

Various modifications can be made to the above-described embodiment. For example, any other suitable materials can be used for the layers of the cover. If desired, coating layer 26 can be omitted.

Any desired numbers of holes 30 and studs 12 can be provided, and these may be located at edges of the cover in addition to, or instead of, at the corners. The holes can be provided in straps or flaps extending from the edges of the main portion of the outer layer 24.

The studs 12 and their shaft portion 18 can be permanently attached to the oilpan or to an adjacent part of the engine block in any convenient way, in particular they can be integral therewith.

Instead of being created before the moulding of the cover, holes 30 may be provided in outer layer 24 after it has been attached to foam layer 22.

In a modification, the foam layer 22 may cover the edge or corner areas 28, and holes aligned with holes 30 may be moulded directly in the foam layer 22. This alignment of holes provides a firmer attachment.

In a further modification, outer layer may be omitted, at least in these areas.

The cover 20 may be arranged to overlie substantially the entire surface of oilpan 10 or only part thereof. Alternatively, two or more covers 20 may be arranged to surround respective parts of oilpan 10.

The shape of the holes in the outer layer 24 may have various forms. For example, in Figure 6 hole 60 has a diameter which is slightly smaller than that of spherical studs 12. The hole has a slit portion 62, which permits resilient deformation of the layer 24 to allow hole 60 to expand to allow passage therethrough of a stud 12. Alternatively in Figure 7, hole 70 has an inner portion with a diameter substantially smaller than that of spherical studs 12. Hole 70 is provided with a plurality of tapering, radially-extending slits 72 in the manner of a star. As with Figure 6, these slots permit resilient deformation to allow passage of a stud 12.

The attachment means of the modification of Figure 6 and 7 are slightly more difficult to connect, but have the advantage over the attachment means of Figure 5 in that they are less likely to be inadvertently released by jolts.

In Figure 8, attachment hole 80 is circular with a diameter substantially smaller than studs 12. In this modification the spherical head of the stud is detachable from its associated shaft position 18. Hole 80 can be placed over shaft portion 18 and then stud 12 can be attached to retain the cover in place. The stud 12 can be attached to its shaft portion by a welding procedure, a snap-fit arrangement or by a screw connection. Different types of stud attachment and/or hole shapes may be employed at different locations of the same sound absorbing cover.

Other shapes may be used for studs 12. In modifications, projections on the cover may engage in corresponding recesses in the oilpan or engine block.

There may be applications in which it is desired to implement further sound absorbing measures. In such cases, embodiments of the present invention may be supplemented by features of our co-pending application entitled "Sound Absorbing Members" and filed on even date. The contents of this co-pending application are hereby incorporated by reference. Thus the sides and/or bottom of the cover 20 may have partially or completely embedded therein sheet inserts to act as sound-limiting elements. The elements are preferably made of sheet metal. The elements preferably do not contact each other, but the lower edges of the side elements are preferably in a load-transmitting configuration with the adjacent edges of the bottom element.

The cover 20 may be configured to surround another sound-emitting component of an engine instead of an oilpan; for example, it would be used as a front cover of an engine. The cover may also be used for other containers and, moreover, other articles; it can be used in association with electric motors, for example.

Reference Numerals oilpan 10 stud 12 oilpan walls 14, 16 shaft portion 18 cover 20 foam layer 22 outer layer 24 coating 26 corner area 28 hole 30 hole lower region 32 hole upper region 34 direction of noise 36 hole 60 slit 62 hole 70 slits 72 hole 80

Claims (15)

1. C LA I MS1, A sound-absorbing cover (20) for a container comprising a resilient outer layer (24) (30, 60, 70, 80) and an inner layer (20) of foam material, the outer layer incorporating attachment means whereby the cover can be attached firmly to the container.
2. 2. A cover according to claim 1, wherein the attachment means are readily releasable.
3. 3. A cover according to claim 1 or 2, wherein the outer layer (24) has at least one edge or corner area (28) which is not covered with foam material, said area having a hole (30, 60, 70, 80) constituting said attachment means for engagement with a projection on the container.
4. 4. A cover according to claim 3, wherein the outer layer (24) has a plurality of said edge and/or corner areas (28) arranged to engage with a plurality of respective projections.
5. 5. A cover according to claim 3 or 4, wherein the or each hole (30) has a keyhole shape.
6. 6. A cover according to claim 3 or 4, wherein the or each hole (60) has a substantially circular shape with a slit (62) extending radially therefrom.
7. 7. A cover according to claim 3 or 4, wherein the or each hole (70) has a circular shape with a plurality of slits (72) extending radially from its periphery.
8. 8. A cover according to any preceding claim, wherein the layer (20) of foam material has an inner coating (26)
9. 9. A cover according to any preceding claim, wherein the foam material (20) is polyurethane foam.
10. 10. A cover according to any preceding claim, wherein the outer layer (24) comprises ethylene propylene terpolymer rubber.
11. 11. A container (10) provided with a cover (20) according to any preceding claim.
12. 12. A container according to claim 11 having one or more attachment means (12) corresponding to the attachment means (30, 60, 70, 80) on the cover (20)
13. 13. A container according to claim 12 wherein the or each attachment means on the container comprises a substantially spherical stud (12)
14. 14. A container according to any of claims 11 to 13, wherein the relative sizes of the container (10) and the cover (20), the relative positions of the attachment means (12, 30, 60, 70, 80) and the degree of resilience of the outer layer (24) are selected so that the cover can be attached tightly to the container.
15. 15. An engine comprising an oilpan (10) constituting the container of any of claims 11 to 14.