GB2319501A

GB2319501A - Acoustic screen between engine and wheels.

Info

Publication number: GB2319501A
Application number: GB9705244A
Authority: GB
Inventors: Gerard Gallas
Original assignee: Draftex Industries Ltd
Current assignee: Laird Holdings Ltd
Priority date: 1996-11-20
Filing date: 1997-03-13
Publication date: 1998-05-27
Anticipated expiration: 2017-03-13
Also published as: GB9705244D0; GB2319501B

Abstract

The acoustic screen made of material having a high acoustic impedance which is mounted between the engine compartment and a front wheel comprises two parts 40,42 which are mounted together in co-planar fashion, edges overlapping, The overlapping edges define slots 44,46,48,50 which form apertures allowing members such as a half shaft to extend between the engine compartment and the wheel. The slots either carry respective half bellows 52,54, which are clipped together to define bellows, or they carry flexible fibres 118a, b embracing the movable members to restrict the radiation of noise from the engine compartment. The screens and the bellows may be made of rubber or thermoplastics material and may be moulded together. Alternatively (Fig. 8) the screen is a single sheet with slots (106, 108) that can slide around the members.

Description

ARRANGEMENTS FOR REDUCING EXTERNAL NOISE FROM MOTOR VEHICLES The invention relates to arrangements for reducing external noise from motor vehicles. Regulations limit the amount of noise which may be radiated externally by motor vehicles, in particular the amount of noise radiated by the vehicle engine. Embodiments of the invention to be described in more detail below by way of example only are intended to assist in meeting the requirements of these regulations.

According to the invention, there is provided a noise-reduction arrangement for motor vehicles, comprising sheet-like material having a high acoustic impedance and a predetermined shape to be mounted in position between the engine compartment of the vehicle and the inside face of a front wheel of the vehicle, the material defining an aperture for allowing movement relative to the material of a member linked to the wheel, the aperture having associated with it means for flexibly and acoustically sealing around the member.

According to the invention, there is further provided an arrangement for reducing external noise from a motor vehicle, comprising two separate sheet-like screens made of material having a high acoustic impedance and each of predetermined shape and for mounting in substantially co-planar fashion in a position between the engine compartment of the vehicle and the inside face of a front wheel of the vehicle with adjacent edges of the screens overlapping each other, the overlapping edges being formed with respective slots for defining an aperture for receiving a member extending from the vehicle body and linked to the wheel when the two screens are mounted in the said position, the member being movable, and the closed ends of the slots defining the aperture carrying respective acoustic sealing means which are brought together to provide an acoustic seal around the member when the screens are mounted in the said position.

According to the invention there is also provided an arrangement for reducing external noise from a motor vehicle, comprising a sheet-like screen made of material having a high acoustic impedance and of predetermined shape and for mounting in a position between the engine compartment of the vehicle and the inside face of a front wheel of the vehicle, the screen being formed with an aperture for receiving a member extending from the vehicle body and linked to the wheel when the screen is mounted in the said position, the screen having a slit or opening extending from an edge of the screen to intersect with the aperture to enable the material to be temporarily bent apart alongside the slit or opening to enable entry of the member into the aperture, the member being movable and the aperture carrying acoustic sealing means which can be temporarily opened out to receive the member when the material is bent apart alongside each slit or opening, the acoustic sealing means thereafter closing around the surface of the member linked to the wheel.

Noise reduction arrangements embodying the invention, and for use in reducing noise radiated by the engines of motor vehicles, will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which.

Figure 1 is a perspective view of part of the front wheel drive transmission, suspension and steering mechanism of a motor vehicle; Figure 2 is a side elevation corresponding generally to Figure 1 and showing where an acoustic screen forming part of one of the arrangements may be mounted; Figure 3 is a perspective view of a half-bellows forming part of one of the arrangements; Figure 4 corresponds to Figure 3 but also shows the other half of the bellows; Figure 5 is a perspective view showing how the two half-bellows of Figure 4 may be clipped together; Figure 6 shows the upper and lower parts of the acoustic screen each carrying two half-bellows and ready for assembly together; Figure 7 shows a modified form which the acoustic screen of Figure 6 can have; Figure 8 shows a modified form of the acoustic screen of Figure 7; Figure 9 is a diagrammatic cross-section on the line IX-IX of Figure 8; and Figure 10 shows a modified form of the acoustic screen parts shown in Figure 6.

Figures 1 and 2 show one of the front, driving, wheels 5 of a motor vehicle, the wheel 5 being driven by the drive shaft 6 from the vehicle engine (not shown) via its gearbox and differential 7 (Fig. 2). The drive shaft is coupled to the wheel 5 by means of a universal joint protected by a flexible bellows 8. The wheel 5 is rotatably supported by bearings 10 (Figure 2) carried by the upper and lower suspension arms 12 and 13 which are pivotally linked to upper and lower wishbones 14 and 16. The wishbones 14,16 are pivotable about horizontal axes 18,20 supported by the vehicle body or chassis and the vehicle suspension is carried out by means of a coil spring 22 (Figure 1). Figure 2 omits the spring but shows the shock absorber 24 which acts between the lower wishbone 16 and part of the vehicle body 26. The upper and lower suspension arms 12 and 13 are pivotable on the wishbones 14 and 16 about pivots having a common axis 28 (Fig. 2) slightly inclined to the vertical. A steering arm 30 (Figure 1) is linked to the upper suspension link 12 and moves in the direction of the arrows A in order to turn the suspension arms 12,13 about the pivot axis 28 and thus to turn the wheel 5 correspondingly for steering purposes.

A substantial amount of noise from the vehicle engine, and the associated transmission parts, will be emitted sideways from the engine compartment towards the wheel 5 (and, correspondingly, on the other side of the vehicle). The noise-reduction arrangement now to be described in more detail below, provides an acoustic screening arrangement for blocking a substantial part of this noise and preventing or reducing its outward radiation through the wheel arch and around the wheel.

The acoustic screening arrangement 38 is shown diagrammatically in Figure 2 and provides a wall extending across the interior of the wheel arch of the vehicle. It has to provide through passages to accommodate the linear movement (in the direction of the arrows A) of the steering arm 30 and the rotary movement of the half-shaft 6, but at the same time providing a reasonable acoustic seal around these movable parts. In order to carry out this purpose, the screen which is shown in more detail in Figure 6 is therefore formed in upper and lower parts 40 and 42 provided with matching slots 44, 46 and 48, 50, the slots 44 and 46 accommodating the steering arm 30 and the slot 48 and 50 accommodating the half-shaft 6. The closed end of each slot 44,46,48 and 50 carries an attached half-bellows, as shown at 52,54,56 and 58. When the two screen parts 40,42 are brought together substantially co-planarly with their slotted edges overlapping, in a manner to be explained in more detail, the half-bellows 52 and 54, and the half-bellows 56 and 58, are brought together tb form a seal around the steering arm 30 and the half-shaft 6.

One of the half-bellows (e.g. the half-bellows 54) is shown in Figure 3. It has a wide end 60 provided with a groove 62 by means of which it may be secured to the respective screen part 40,42, around the edge of the end of the respective slot 44,46,48 or 50. From the wide end 60, flexible pleated material extends to a narrow end 64 provided with a semi-circular clip 66. Figure 4 shows the corresponding upper half-bellows (e.g. the halfbellows 52). This is of matching construction and mates with the lower half-bellows as shown in Figure 5. In Figure 4, the narrow end of the upper bellows part is omitted to show its construction. Figure 5 shows how the clip 66 (Figure 2) and a corresponding clip 70 may be used and inter-engaged to hold the two half-bellows together, each clip having a locking part 72,74 for engaging a shoulder 76,78.

In operation, the two screen parts 40,42 (Figure 6) are separately placed into position, from above and below the suspension of the vehicle wheel 5 (Figures 1 and 2), and then brought vertically together so that the half-bellows 52,54 come together around the steering arm 30 and the half-bellows 56 and 58 come together around the half-shaft 6. When the half-bellows pairs have properly inter-engaged, they are secured together by means of the clips 66 and 70 as shown in Figure 5.

The screen parts 40,42 are also provided with further slots 80,82,84 and 86 (see Figure 6) which, when the screen parts 40,42 are brought together, form apertures for receiving, the suspension linkage. It will be noted from Figure 2 that the screening arrangement is preferably mounted so as to be aligned with the pivot points 18,20 of the wishbones 14,16 so that it does not have to accommodate wishbone movement. Other apertures may be provided for connections such as hydraulic pipes.

Figure 6 also shows holes 88 in the screen parts 40,42 for receiving suitable fixtures either for fixing the two screen parts together when they are mounted in overlapping relationship or for fixing the screen parts, to the adjacent body work. In addition, the lower screen part 42 may be provided with rigid members 89 extending along its lower edge for strengthening it where it crosses the wheel arch opening.

The screen parts 40,42, and the half-bellows 52,54,56 and 58 are made of material having good sound-deadening characteristics and also, of course, having suitable mechanical characteristics and the ability to withstand heat, cold and water and all other environmental effects likely to be encountered. The screen parts 40,42 can be made in rigid or semi-rigid material, such as steel or plastics material, covered on at least the inside with soundabsorbing material, such as flexible or rigid foam. Instead of rigid material for the body of the screen parts, a more flexible material can be used if it can be given the required mechanical characteristics, obtained for example by sufficient density or thickness; rubber or thermoplastics material may be possible.

Recyclable materials can also be used if they can meet the required characteristics. The half-bellows 52,54,56 and 58 can be made from a suitable flexible elastomer or thermoplastic material. Advantageously, they can be covered on their internal faces with a sound-absorbing material such as foamed or cellular plastics material. The thickness of the absorbent material must not be so great as to limit the flexibility of the bellows to an undesirable extent.

The half-bellows 52,54,56 and 58 can be joined to the screen parts 40,42 in any suitable way, such as by clipping or adhesive.

Advantageously, however, they can be integrally moulded with the material of the screen parts.

It will be understood that the exact shape of the screen parts 40,42 and the position, number and size of the half-bellows 52,54,56 and 58 will depend on the layout of the transmission and suspension of the vehicle. In the case where the rear wheels of the vehicle, rather than its front wheels, are driven, the construction of the acoustic screening system will be simplified.

Fig. 2 shows how the lower screen part 42 can have an extension 42A extending horizontally under the drive shaft 6.

Figure 7 shows a modified form of the acoustic screening arrangement. Parts corresponding to parts in other Figures are similarly referenced. In the arrangement of Figure 7, the acoustic screen is not in two parts (as shown in Figure 6) but is a single part 100. In addition, each bellows is in the form of a single bellows 102,104 instead of being in the form of two bellows halves (as shown in Figure 6). In order to enable the screen 100 to be mounted in position, it is provided with two slits 106,108, each of which extends from the lower edge of the screen 100 up to and through the wall of a respective one of the bellows 102,104. Each bellows 102,104 is provided with a longitudinally extending through slit 110,112 communicating with the respective slit 106,108. The slits 106 and 108 enable the screen to be fitted in position on the vehicle, the material of the screen on each side of the slits 106,108 being bent apart to enable the screen to be placed in position over the steering arm 30 and the half-shaft 6. In addition the extension of each slit 106,108 through the wall of a respective one of the bellows enables each bellows to be opened out to embrace the steering arm or the half-shaft, as the case may be, the bellows then resiling around these members. If desired, clips may be provided to mould each slit 106,108 firmly closed after assembly on the vehicle in this way.

The screen 100 and the bellows 102,104 may be made of the same material as for the screen parts and the half-bellows of Figure 6.

The screen 100 of Figure 7 may of course be modified to suit the layout of a particular vehicle. Additional slits may be provided to accommodate other parts of the vehicle such as hydraulic pipes and the like.

In the modified screen shown in Figure 8, parts corresponding to those in Figure 7 are similarly referenced.

In the acoustic screen of Figure 8, the bellows 104 is replaced by an arrangement of flexible fibres indicated generally at 118.

There are two sets 120 and 122 of the fibres 118 which are secured by respective supports 124 and 126 (see Figure 9) running along opposite longitudinal sides 128 and 130 of a rectangular aperture 132 in the screen 100. The aperture 132 is connected to and open to the slot 108. During the mounting process, the material of the screen on each side of the slit 108 is bent apart, thus tending to splay the sides 128 and 130 of the aperture 132 apart, to allow entry of the half-shaft 6. The separated parts of the screen 100 then come together again and the fibres 118 assure acoustic sealing around the relevant member 30 or 6. During the mounting process, of course, the slit 106 and the bellows 110 are also opened out in the manner already explained.

The flexible fibres 118 are made of suitable material so as not to cause abrasion of the half-shaft. The material of the fibres must also be such that it retains good flexibility during the whole of the working life of the screen.

The fibres can be attached in position in any suitable way and not merely by means of the supports 124 and 126. For example, they can be secured by clipping or adhesive or by moulding or over-moulding. Clearly, the bellows 102 could also be replaced by fibres similar to the fibres 118.

Figure 10 shows a modified form of the acoustic screen parts of Figure 6, in which the upper and lower bellows parts 56,58 are replaced by upper and lower arrangements of fibres 118A and 118B.

These fibres, which may be of the same type as shown in Figures 8 and 9 and secured in position by any suitable means such as by supports 124A,124B,126A,126B as explained in connection with those Figures, come together to form an acoustic seal around the half-shaft 6 when the two screen parts 40,42 are attached together in the manner explained in connection with Figure 6.

Claims

1. A noise-reduction arrangement for motor vehicles, comprising sheet-like material having a high acoustic impedance and a predetermined shape to be mounted in position between the engine compartment of the vehicle and the inside face of a front wheel of the vehicle, the material defining an aperture for allowing movement relative to the material of a member linked to the wheel, the aperture having associated with it means for flexibly and acoustically sealing around the member.

2. An arrangement according to claim 1, in which the means for flexibly and acoust ally sealing around the member comprises bellows means.

3. An arrangement according to claim 2, in which the bellows means comprises a bellows separated along a longitudinal plane into two parts which are brought together to define the bellows when the sheet-like material is mounted in the said position.

4. An arrangement according to claim 11, in which the means for flexibly and acoustically sealing around the member comprises a set of flexible members extending partway across the aperture from the edge thereof and having free ends.

5. An arrangement according to any preceding claim, in which the sheet-like material is in a plurality of parts.

6. An arrangement according to claim 1, in which the sheet-like material is in two parts and in which the aperture is defined by respective slots in edges of the two parts of the material which are brought overlappingly together when the material is mounted in the said position.

7. An arrangement according to claim 6, in which the means for flexibly apd acoustically sealing around the member comprises bellows formed by two bellows parts separated along a longitudinal plane through the bellows, one bellows part being attached to one part of the material and the other bellows part being attached to the other part of the material, the two bellows parts being mated together when the material is mounted in the said position.

8. An arrangement according to claim 7, including fastening means for attaching the two bellows parts together.

9. An arrangement according to claim 6, in which the means for flexibly and acoustically sealing around the member comprises two sets of flexible members, the flexible members of each set extending partway across a respective one of the slots from the opposite parts of the boundary thereof and having free ends at least some of which contact the surface of the member linked to the wheel when the material is mounted in the said position.

10. An arrangement according to claim 1, in which the aperture is connected to an edge of the sheet-like material by a slit or opening in and through the material whereby the material along opposite sides of the slit or opening may be bent apart to allow entry of the member into the aperture, the material then resiling to substantially close the slit or opening.

11. An arrangement according to claim 10, in which the means for flexibly and acoustically sealing around the member comprises a bellows, the wall of which is cut through along a line extending longitudinally of the bellows, the line intersecting with the slit or opening to enable the bellows to be opened out along the line to allow entry of the member into the bellows when the material along opposite sides of the slit or opening is bent apart, the material of the bellows thereafter resiling.

12. An arrangement according to claim 11, in which the means for flexibly and acoustically sealing around the member comprises a set of flexible members extending part way across the aperture from opposite edges thereof and having free ends at least some of which contact the surface of the member linked to the wheel when the material is mounted in the said position.

13. An arrangement according to any one of claims 10 to 12, including clip means for securing together the material along opposite sides of the slit.

14. An arrangement according to any preceding claim, in which the member linked to the wheel is a longitudinally movable steering link for adjusting the steering angle of the wheel.

15. An arrangement according to any preceding claim, in which the member linked to the wheel is a rotatable drive shaft for the wheel.

16. An arrangement according to any preceding claim, in which the sheet-like material and the means for flexibly and acoustically sealing around the member are moulded together.

17. An arrangement according to any preceding claim, in which the sheet-like material and the means for flexibly and acoustically sealing around the member are made of rubber or thermoplastics material.

18. An arrangement according to claim 17, including acoustic damping material attached to the rubber or thermopiastics material.

19. An arrangement for reducing external noise from a motor vehicle, comprising two separate sheet-like screens made of material having a high acoustic impedance and each of predetermined shape and for mounting in substantially co-planar fashion in a position between the engine compartment of the vehicle and the inside face of a front wheel of the vehicle with adjacent edges of the screens overlapping each other, the overlapping edges being formed with respective slots for defining an aperture for receiving a member extending from the vehicle body and linked to the wheel when the two screens are mounted in the said position, the member being movable, and the closed ends of the slots defining the aperture carrying respective acoustic sealing means which are brought together to provide an acoustic seal around the member when the screens are mounted in the said position.

20. An arrangement according to claim 19, in which the acoustic sealing means comprises respective part-tubular bellows parts extending transversely to the plane of the respective screens so as to be brought together to define a bellows embracing the movable member when the screens are mounted in the said position.

21. An arrangement according to claim 20, including fastening means for fastening the two bellows parts together.

22. An arrangement according to claim 21 or 22, in which the bellows is of frusto-conical shape and the larger-sized end of each bellows part is attached to the respective screen.

23. An arrangement according to any one of claims 20 to 22, in which each bellows part is integrally moulded with the respective screen.

24. An arrangement according to claim 19, in which the acoustic sealing means comprises two sets of flexible members, the flexible members of each set extending partway across a respective one of the slots from the opposite parts of the boundary thereof and having free ends at least some of which contact the surface of the member linked to the wheel when the material is mounted in the said position.

25. An arrangement for reducing external noise from a motor vehicle, comprising a sheet-like screen made of material having a high acoustic impedance and of predetermined shape and for mounting in a position between the engine compartment of the vehicle and the inside face of a front wheel of the vehicle, the screen being formed with an aperture for receiving a member extending from the vehicle body and linked to the wheel when the screen is mounted in the said position, the screen having a slit or opening extending from an edge of the screen to intersect with the aperture to enable the material to be temporarily bent apart alongside the slit or opening to enable entry of the member into the aperture, the member being movable and the aperture carrying acoustic sealing means which can be temporarily opened out to receive the member when the material is bent apart alongside each slit or opening, the acoustic sealing means thereafter closing around the surface of the member linked to the wheel.

26. An arrangement according to claim 26, in which the acoustic sealing means comprises a bellows extending transversely to the plane of the screen, the slit or opening intersecting with a cut through the wall of the bellows, the cut extending longitudinally of the bellows to enable the bellows to be temporarily opened out to receive the member, the material of the bellows thereafter resiling to embrace the surface of the member linked to the wheel when the screen is mounted in the said position.

27. An arrangement according to claim 26, in which the bellows is of frusto-conical shape and its larger-sized end is attached to the screen.

28. An arrangement according to claim 26 o 27, in which the bellows is integrally moulded with the screen.

29. An arrangement according to claim 25, in which the acoustic sealing means comprises a set of flexible members extending part way across the aperture from opposite edges thereof and having free ends at least some of which contact the surface of the member linked to the wheel when the material is mounted in the said position.

30. An arrangement according to any one of claims 4,9,12,24 and 29, in which the flexible members are flexible fibres.

31. An arrangement for reducing external noise from motor vehicles substantially as described with reference to Figures 1 to 6 of the accompanying drawings.

32. An arrangement for reducing external noise from motor vehicles, substantially as described with reference to Figures 1,2 and 7 of the accompanying drawings.

33. An arrangement for reducing external noise from motor vehicles, substantially as described with reference to Figures 1,2,8 and 9 of the accompanying drawings.

34. An arrangement for reducing external noise from motor vehicles, substantially as described with reference to Figures 1,2 and 10 of the accompanying drawings.