WO2011048163A1

WO2011048163A1 - Underfloor wind noise blade

Info

Publication number: WO2011048163A1
Application number: PCT/EP2010/065833
Authority: WO
Inventors: Peter F. Tindall; Stuart Gardner; Charles J. Darlington
Original assignee: Jaguar Cars Limited
Priority date: 2009-10-20
Filing date: 2010-10-20
Publication date: 2011-04-28

Abstract

A blade adapted to depend from the underside of a vehicle so as to disrupt airflow under the vehicle and reduce cabin noise. In an embodiment, the blade is castellated.

Description

UNDERFLOOR WIND NOISE BLADE

Technical Field The present invention relates to blades and other devices suitable for use in disrupting airflow in a manner that reduces noise experienced by occupants within a vehicle, such as but not limited to the type suitable for use under the floor of automobiles. Aspects of the invention relate to an apparatus and to a vehicle. Background

It is known that the airflow passing under a moving vehicle is a source of noise for the occupants of the vehicle. It is an aim of the present invention to address this issue. Embodiments of the invention may provide an apparatus arranged to disrupt the airflow passing beneath the vehicle when in motion so as to reduce noise generated thereby without significantly increasing drag. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.

Summary

Aspects of the invention therefore provide an apparatus and a vehicle as claimed in the appended claims.

According to another aspect of the invention, there is provided an apparatus for a vehicle comprising a blade member arranged to be attached to an underside of the vehicle so as to protrude into an airflow passing under the vehicle in motion, the blade member being arranged to disrupt the airflow so as to reduce noise generated.

In an embodiment, the blade is arranged to deflect at least a part of the airflow in a lateral direction of the vehicle.

In an embodiment, the blade is arranged to be attached to the underside of the vehicle in a cross-wise orientation. In an embodiment, the blade in use extends substantially across the width of the vehicle. In an embodiment, the blade includes at least one castellation.

In an embodiment, the depth of the or each castellation lies between approximately 25mm and approximately 50 mm.

In an embodiment, the length of the or each castellation is between approximately 10mm and approximately 150mm.

In an embodiment, a gap between the or each castellation is between approximately 10mm and approximately 100mm.

The apparatus may comprise a plurality of castellations. In an embodiment, the outermost castellation at one or both ends of the apparatus have a different depth or length than other castellations.

In an embodiment, one of the plurality of castellations has a different depth and/or length than another of the plurality of castellations.

In an embodiment, the or each castellation is generally square or rectangular in shape.

According to another aspect of the invention for which protection is sought, there is provided a vehicle having an apparatus as claimed in any preceding claim. In an embodiment, the apparatus is integrally formed with a part of the underside or underfloor of the vehicle. In an embodiment, the apparatus is attached to the underfloor or underside of the vehicle by bolts, rivets, welds or any other suitable attachment.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination. Features described with reference to one embodiment are applicable to other embodiments, except where there is incompatibility of features.

Description

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates an apparatus embodying one form of the invention;

Figure 2 illustrates the apparatus of Figure 1 in situ on a vehicle; Figure 3 illustrates an example of a suitable location for mounting the apparatus of Figure 1 on a vehicle;

Figure 4a illustrates airflow under a vehicle not equipped with the apparatus of Figure 1 ; Figure 4b illustrates airflow under a vehicle equipped with the apparatus of Figure 1 ;

Figures 5a - 5c illustrate mass air flow velocity under a vehicle not equipped with the apparatus of Figure 1 ; Figures 6a-6c illustrate mass air flow velocity under a vehicle equipped with the apparatus of Figure 1 ;

Figure 7a illustrates sound pressure levels measured for a vehicle not equipped with the apparatus of Figure 1 ;

Figure 7a illustrates sound pressure levels measured for a vehicle equipped with the apparatus of Figure 1 ;

Figures 8a-8d illustrate a sound level measured within a vehicle with and without the apparatus of Figure 1 ;

Figure 9 is an enlarged view of a portion of the apparatus of Figure 1 ;

Figure 10 illustrates sones values for the apparatus of Figure 1 and for another form of the apparatus embodying the invention without castellations.

Figures 1 1 a-1 1 c respectively illustrate drag, front vehicle lift, and rear vehicle lift for a vehicle equipped with an apparatus according to the invention; and FIGURE 12 illustrates other configurations and positions for the apparatus according to non- limiting embodiments of the present invention. For exemplary purposes the present invention is predominately described with respect to an apparatus in the form of a blade configured to counteract air flow along an underside of an automobile in a manner that reduces noise heard by passengers. This exemplary description is not intended to limit the scope and contemplation of the present invention. The present invention fully contemplates the blade being applied in other non-automotive environments where the advantages attendant to the present invention may be suitably used or adapted to reduce noise or otherwise disrupt/redirect airflow in a beneficial manner.

The blade contemplated by one non-limiting aspect of the present invention is shown in FIGURE 1 at reference numeral 10. The blade 10 has a generally L-shaped construction with an attachment flange 12 and a castellated flange 14. The blade 10 may be divided into two mirrored halves 10a, 10b, with each half having a number of castellations 16. One option is to have a consistent number and size of castellations on each half. Depending on the cross-car width, this may or may not be possible with each castellation having the same size.

The illustrated configuration has a cross-car width such that the size of the first or outermost castellation 16 is slightly larger than the other castellations in order to provide uniform airflow exposure. The first castellation 16 may also be slightly wider to provide a larger surface across the boundary of the wheel shield, for example to provide a surface for an interference fit/contact between the shield and blade. The last or innermost castellation 16 in each half 10a, 10b may be halved in sized so that it can be joined with a correspondingly halved castellation to form a full castellation. The blade 10 may be formed out of any suitable material, such as but not limited to a rigid material (steel, aluminum, alloy, etc.) or a semi-rigid material (plastic, rubber, etc.). One non- limiting aspect of the present invention contemplates the blade 10 being constructed of a semi-rigid or semi-bendable material so that it can withstand rock strikes or other impacts or forces during vehicle operation without having to be completely replaced.

In one advantageous but non-limiting example, the material may be constructed according to the following parameters:

The attachment flange 12 may be used to attach the blade to the underbody 18 of the vehicle. It may include a number of apertures 20 for use with fasteners in attaching the blade 10 to the underside of a vehicle. The halving of the blade 10 may be helpful in facilitating this attachment since an assembler required to position and attach the blade halves 10a, 10b can be corresponding! smaller in comparison to that which would be necessary when attaching a one-piece blade. Of course, the present invention fully contemplates the use of a one-piece blade as well as blades comprising more than two pieces.

FIGURE 2 illustrates attachment of the blade 10 to the underside of the vehicle in accordance with one non-limiting aspect of the present invention. While the attachment is shown for exemplary purposes as being performed with a threaded bolt 22 proximate a front wheel arch 24, the present invention fully contemplates other non-removable attachment arrangements such as, but not limited to, welding.

The attachment location of the blade 10 to the underfloor 18 of the vehicle is selected according to the shape and configuration of the vehicle or, more specifically, according to mass airflow characteristics of the vehicle, so that the mass airflow can be disrupted in a manner that reduces noise heard by passengers. In general, this may be achieved by locating the blade 10 as far rearward as possible while maintaining its position in front of a front wheel envelope of the front wheels 30a, 30b. FIGURE 3 illustrates the positioning of the blade 10 in this manner where the blade is slightly forward of the front wheel envelope and extends cross-car to slightly overlap the inside edges of both wheel envelopes. The present invention, however, also contemplates the blade 10 extending widthwise across the entire width of the vehicle such as, but not limited to, stretching from one front-quarter panel to the other.

The illustrated positioning of the blade 10 causes the a disruption in the mass airflow that is beneficial manner in so far as reducing wind noise heard by occupants within the vehicle. This distribution of mass airflow by the blade 10 is shown schematically in FIGURES 4a-4b where Figure 4a illustrates airflow without the blade and Figure 4b illustrates airflow with the blade. The diagrams indicate the pattern of airflow as directed around existing static structures (wheel envelope, etc.) wherein the blade causes more air to be directed toward the extremities of the vehicle. This means that less air travels underneath the remainder of the car and directly underneath the passenger cabin. That is to say, this reduction in mass airflow has a direct relationship with reducing the loudness experienced in the cabin. There may be some localised noise caused by separating and turning of airflow proximate the blade but this effect is attenuated and not apparent to the passengers due to the other vehicle components in the area and since it interacts with less noise generating components of the vehicle in comparison to the areas under the vehicle. The mass airflow benefits of the blade 10 can also be understood by comparing mass airflow underneath a vehicle having the blade and the same vehicle without having the blade. FIGURES 5a-5c illustrate mass airflow velocity measured across an underside of a selected vehicle without the blade and FIGURES 6a-6c illustrate the mass airflow velocity measured across the underside of the same vehicle after attachment of the blade.

Alternatively to the velocity measurements, FIGURES 7a-7b respectively illustrate sound pressure levels measured without and with the blade. The three circled areas of Figure 7b particularly illustrate areas of important changes - the outward two areas indicating particularly panel areas susceptible to noise (at least partially due to thinness and lack of strength of these area) having less sound pressure and the central area indicating an area having increase sound pressure levels where noise increase is generally unnoticed (at least partially due to the thickness and rigidity of this area). The graphs represent the change in mass airflow according to changes in velocity and pressure. Figures 5a and 6a, for example, indicate an area inside of each wheel envelope to have higher velocity without the blade than with the blade. This area of higher velocity causes a pressure differential between the inboard and outboard side of the wheel shield (high velocity results in less pressure, lower velocity results in higher pressure, and air flow tends to move from high pressure to low pressure). The pressure differential generally results in undesirable noise as the air tends to flow with more force between areas having greater disparities in pressure. The blade tends to reduce or balance the pressure differential between the sides of the wheel shield in a manner that reduces noise heard by vehicle occupants. Noise may also be decreased due to some of the mass airflow being redistributed away from a central area under the passenger compartment to an area outboard of the front wheel envelope. The amount of noise heard by vehicle occupants can be measured with an acoustic head or sound pressure level meter placed within the passenger cabin to measure sound according to sound pressure level and audible frequency ranges. FIGURES 8a-8b illustrate such a measurement with respect to the vehicle travel at 0°Yaw and FIGURES 8c-8d illustrate the measurement at 10° Yaw to represent passenger compartment noise throughout most ranges of vehicle operations. That is, typically the underflow airflow will be in the range of 0- 8° Yaw. With respect to Figures 8a and 8c, the top lines illustrate noise without the blade and the bottom lines illustrate noise with the blade. With respect to Figures 8b and 8d, the bars indicate noise change with the blade relative to a zero axis baseline determined from performance without the blade. As noted, the blade provides an approximate 1 .3 sones improvement at 160 kph at 0⁰ Yaw and at 10⁰ Yaw.

The ability of the blade to disrupt mass airflow in this manner is provided in part by its L- shaped configuration. More specifically, the disruption may be facilitated with the castellated flange extending downwardly away from the floor of the vehicle to interrupt the mass airflow. FIGURE 9 illustrates an exemplary configuration of the castellated flange in accordance with one non-limiting aspect of the present invention. The blade shown in Figure 9 differs slightly from the blade shown in Figure 1 in that the inside corners between castellation are squared instead of curved. The rounded grooves may be helpful in minimizing stress on the blade during manufacture in comparison to the square grooves while the square grooves may be helpful in minimizing manufacturing time in comparison to the more difficult to cut rounded grooves. The dimension of the castellations and spacing therebetween in Figure 9 are represented with the illustrated letters where a = 25mm; b = 20mm; c = 50mm; d = 50mm; and p = q = r = s = 90 °. Of course, as shown in Figure 1 the present invention is not necessarily limited to these dimensions as the configuration shown in Figure 1 includes a = 50mm, c = 50.48 mm, d = 49.29mm, and an overall length of 1250mm (the first castellation has d = 74.39 and the end castellation has d = 24.65). The airflow disruption shown in Figure 5a-5c was measured with a=50mm. Given this dimension and the illustrated positioning, it was determined that the blade was able to produce a 2.0 sones difference in the passenger compartment when traveling at 160 kph and 0° yaw.

The blade described above to distribute the mass airflow in the illustrated manner includes a number of castellations. The sones improvement of 1 .3 noted above with respect to Figures 8a-8d was determined for a castellation height of 25mm. The sones value can be improved by increasing the height to 50mm and/or by replacing the castellation with solid materials, i.e., providing a uniform L-shaped cross-section throughout. FIGURE 10 illustrates sones values for the blade with and without castellations as a function of height and sones values (the top two dots represent the blade without castellations and the bottom two dots represent the blade with castellations). As shown, greater sound reductions are achieved by increasing the height of the blade and by decreasing the gap (i.e., to none in the case of a solid blade) between castellations.

While the blade having a solid or non-castellated flange improves performance, the increase surface area increases drag. As such, the shape and size of the castellations, or lack thereof, can be used to influence vehicle aerodynamics. This relationship is shown in FIGURES 1 1 a- 1 1 c where the figures respectively illustrate drag, front vehicle lift, and rear vehicle lift. The illustrations of Figures 10 and 1 1 a- 1 1 c are particular to shape of the vehicle: the illustrated vehicle has a shape such that the front positioning (proximate to front nose of vehicle) and the back position (close to and in front of front wheel envelope/shields) are particularly dependent. That is, the illustrations are for a sedan whereas an SUV may not have the same variability due to its increase ride height.

The use of castellations has been found to be useful in balancing the amount of mass airflow disruption versus the amount of drag. While the non-castellated blade may be provided for a greater amount of mass airflow disruption, it also increases the amount of drag to a point where the slight decrease in disruption provided by the castellations was found to be more advantageous than having the additional drag induced by no castellations. In some cases, the use of the blade may introduce lift (see Figure 1 1 b where back location introduces higher levels of front vehicle lift) that may need to be offset with additional measures such as, but not limited to, the use of additional spoilers, like the arcuate shaped spoilers positioned in front of the blade shown in Figure 2. While the foregoing illustrates particular shapes and configurations for the blade, the present invention is not intended to be limited to illustrated castellations and fully contemplates the use of non-castellated blades or blades having other configurations. For example, FIGURE 12 illustrates other configurations and positions for the blade in accordance with other non- limiting aspects of the present invention. In this case, the dimension of 50mm refers to the castellations being 50mm square with a gap of equal dimension between. The other configurations are shown with respect to measured sones values of each. These measurements were taken on the same vehicle for each configuration. The measured values are listed by leader line to the respective blade which is labeled in the Figure as a spoiler. As shown, the blade position illustrated in Figure 3 provided the greatest reduction in noise heard by the occupants. While this positioning may provide the best results, the present invention fully contemplates the use of any one or more of the other spoilers, such as by combining the use thereof with the blade of Figure 3 or otherwise replacing the blade of Figure 3 with one or more of the other spoilers. As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale, some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.

It is expressly stated that the apparatus defined in any of the claims appended hereto can be combined with any of the features, configurations, dimensions, parameters or variations disclosed in any portion of this application and that any and all such combinations are envisaged within the scope of this application.

Claims

CLAIMS:

1 . An apparatus for a vehicle comprising a blade member adapted to depend from an underside of the vehicle in a cross-wise orientation and to protrude into an airflow passing under the vehicle in motion, the blade member including at least one castellation and being arranged to deflect at least a part of the airflow in a lateral direction of the vehicle.

2. An apparatus as claimed in claim 1 , wherein the depth of the or each castellation is any height between approximately 25mm and 50 mm.

3. An apparatus as claimed in claim 1 or claim 2, wherein the length of the or each castellation is between approximately 10mm and 150mm.

4. An apparatus as claimed in any preceding claim, wherein a gap between the or each castellation is between approximately 10mm and 100mm.

5. An apparatus as claimed in any preceding claim, comprising a plurality of castellations, wherein the outer most castellation at one or both ends of the apparatus have a different depth or length than other castellations.

6. An apparatus as claimed in any preceding claim, comprising a plurality of castellations, wherein one of the plurality of castellations has a different depth and/or length than another of the plurality of castellations.

7. An apparatus as claimed in any preceding claim, wherein the or each castellation is generally square or rectangular in shape.

8. A vehicle having an apparatus as claimed in any preceding claim.

9. A vehicle as claimed in claim 8, wherein the apparatus is integrally formed with a part of the underside or underfloor of the vehicle.

10. A vehicle as claimed in claim 8, wherein the apparatus is attached to the underfloor or underside of the vehicle by bolts, rivets, welds or any other suitable attachment.