Air-directing device for a motor-vehicle body, and motor-vehicle body

An air-directing device for a motor-vehicle body includes an air-directing element having a longitudinal axis and being accommodated in a guide element of the air-directing device. The air directing device additionally includes a flow channel formed in between the guide element and the air-directing element, wherein flow can take place through the flow channel starting from an entry opening, which faces toward a front of the motor-vehicle body, and extending through an exit opening, which faces away from the entry opening. The air-directing device is designed so that the air flowing through the flow channel is guided thereby such that it can flow out of the exit opening transversely to an outer contour of the air-directing element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit to German Patent Application No. DE 10 2018 100 522.9, filed Jan. 11, 2018, which is hereby incorporated by reference herein.

FIELD

The invention relates to an air-directing device for a motor-vehicle body, and to a motor-vehicle body having an air-directing device.

BACKGROUND

Air-directing devices for motor-vehicle bodies are known. They serve to guide an air stream forming along the motor-vehicle body, and can be used to create enhanced lift and to reduce drag. The air-directing devices of this kind are usually also referred to as spoilers.

Laid-open application DE 27 26 507 A1 discloses an air-directing device which is intended for a motor-vehicle body and has a throughflow channel. The throughflow channel serves to guide air which is generated with the aid of an air-flow generator, such as for example a compressor of a turbocharger, is guided if required through the throughflow channel and is intended to influence lift of the motor vehicle.

EP 0 969 981 B1 discloses an air-directing device for influencing the noise created by an open sunroof of a motor-vehicle body. The air-directing device is arranged to face toward a front of the motor-vehicle body, in front of the sunroof. With the aid of the air-directing device, the air flowing along the motor-vehicle body is deflected upward, and thus away from the motor-vehicle body, at least to some extent in front of the sunroof. Some of the air is deflected into a flow gap, which is formed between the air-directing device and the motor-vehicle body and is guided more or less vertically upward relative to the motor-vehicle body, in front of the sunroof. Fitting the air-directing device on the motor-vehicle body in front of the sunroof, however, means that said device, at best, has no influence on the lift and the drag of the motor vehicle.

EP 1 630 080 B1 discloses an air-directing device for influencing the downforce and the drag, it being possible for flow to take place beneath the air-guide element of said air-directing device. It is not just the case here that the air flows along a directing surface facing away from the motor-vehicle body; rather, it is guided through a gap formed between the motor-vehicle body and the air-guide element. The air-directing device is arranged in a rear-end region of the motor-vehicle body.

SUMMARY

In an embodiment, the present invention provides an air-directing device for a motor-vehicle body, wherein the air-directing device is configured to be provided in a rear-end region of the motor-vehicle body. The air-directing device includes an air-directing element having a longitudinal axis and being accommodated in a guide element of the air-directing device. A flow channel formed between the guide element and the air-directing element, wherein flow can take place through the flow channel starting from an entry opening, which faces toward a front of the motor-vehicle body, and extending through an exit opening, which faces away from the entry opening. The air-directing device is configured so that the air flowing through the flow channel is guided thereby such that it can flow out of the exit opening transversely to an outer contour of the air-directing element.

DETAILED DESCRIPTION

Embodiments of the present invention provide improved air-directing devices which are intended for a motor-vehicle body and with the aid of which there is a further increase in downforce without any increase in a drag coefficient. Embodiments of the invention also provide motor-vehicle bodies having improved driving dynamics.

An air-directing device according to the invention for a motor-vehicle body is provided in a rear-end region of the motor-vehicle body. It has an air-directing element, which has a longitudinal axis and is accommodated in a guide element of the air-directing device, a flow channel being formed in the process between the guide element and the air-directing element. Flow can take place through the flow channel starting from an entry opening, which faces toward a front of the motor-vehicle body, via an exit opening, which faces away from the entry opening. According to the invention, the air-directing device is designed so that the air flowing through the flow channel is guided thereby such that it can flow out of the exit opening essentially transversally, in particular perpendicularly, to an outer contour of the air-directing element. This means, in other words, that the air flowing through the flow channel is guided upward, and thus away from the vehicle body, at the exit opening, in particular perpendicularly to the outer contour. The advantage of the directing device according to the invention can be considered that of the air which flows via the exit opening more or less perpendicularly to the outer contour, in particular to the upper surface of the air-directing element, having the effect of a conventional spoiler, which is set in position to reduce the lift and increase the downforce. This means that the air-directing element need not necessarily be adjustable in order for the lift acting, in particular, on a rear axle of the motor vehicle to be reduced. In addition, stabilization is achieved in respect of rear-end outflow and thus of the driving dynamics of the motor vehicle.

In particular it is possible, when an upper surface of the air-directing element is positioned at least in alignment with a virtual extension of a roofline, and/or beneath the virtual extension of the roofline, of the motor-vehicle body, for the drag of the motor-vehicle body to be reduced in addition.

In one configuration, a first separation edge of the guide element has, along its virtual extension, a projecting portion in relation to a second separation edge of the air-directing element. This configuration assists in stalling flow.

The flow channel can have a constant flow cross section. It is likewise possible, starting from the entry opening, for it to taper at least to some extent in the direction of the exit opening. The tapering of the flow cross section leads to an increase in the speed of the air stream in the flow channel, as a result of which the downforce can be increased in addition.

In a further configuration, the air-directing element is designed in the form of a shaped element. This means, in other words, that in particular the entry edge and/or the separation edge of the air-directing element are not designed in the form of a rectilinear edge; rather, these edges cover variable progression in particular along the longitudinal extent and along the width extent of the air-directing element. Visual effects, but in particular aerodynamic effects, can be involved here, wherein the shape of the entry and separation edges can influence the inflow and outflow.

If the air-directing element is designed symmetrically in relation to its longitudinal axis, in particular if the air-directing element is designed in the form of a shaped element, improved stability of the driving dynamics can be achieved.

The air-directing device preferably has at least one chamber, wherein flow can take place through the chamber in the direction of the longitudinal axis of the air-directing element. This makes it possible to achieve improved downforce, i.e. higher downforce than if, for example, the air-directing device were fastened at its center point on the guide element with the aid of a retaining element, in which case free flow through the flow channel would take place at least along outer edges of the air-directing element. If there are a plurality of chambers, the desired downforce can be achieved in a more differentiated manner. The plurality of chambers can achieve uniform throughflow through, and outflow from, the flow channel.

In order for the air-directing element to be fastened securely on the guide element, it is connected to the guide element with the aid of elements which extend in particular in the direction of its longitudinal axis. These elements can preferably be the already present outer edges of the directing element, but it is likewise also possible for additional supports, with which the chambers can be formed, to serve for fastening purposes.

A second aspect of the invention relates to a motor-vehicle body having an air-directing device for influencing downforce and a drag coefficient, wherein the air-directing device is designed so that the air flowing through a flow channel is guided thereby such that it can flow out of an exit opening essentially transversely, in particular perpendicularly, to an outer contour of the air-directing element. This motor-vehicle body has, in particular, low drag coefficients, a reduction in lift and stable driving dynamics, as a result of which it is possible to reduce fuel consumption of a motor vehicle equipped with the motor-vehicle body according to the invention.

A motor vehicle1designed in accordance withFIG. 1has a body2according to the invention, which has an air-directing device4according to the invention arranged in a rear-end region3of the motor-vehicle body2.

The air-directing device4is provided in order to reduce lift along a rear axle5of the motor vehicle1and is arranged in the region of a rear edge6of the roof at the rear-end region3, above a rear window7of the rear-end region3.

The air-directing device4comprises an air-directing element8and a guide element9, wherein the guide element9is of shell-like design and accommodates the air-directing element8. The guide element9is connected in a releasable manner to the motor-vehicle body2and extends essentially along a width of the motor-vehicle body2, that is to say transversely to a longitudinal axis41of the vehicle. Relative to its extent along the width of the motor-vehicle body2, the guide element9has a small extent in the direction of the longitudinal axis41of the vehicle.

A flow channel10, through which flow can take place and which has an entry opening11and an exit opening12, is formed between the air-directing element8and the guide element9, wherein flow can take place through the flow channel10along the longitudinal extent of the motor vehicle1. The entry opening11faces toward a front13of the vehicle, and the exit opening12faces away from the entry opening11.

A flow ramp15is formed upstream of the flow channel10, that is to say, in other words, in front of the air-directing element8, as seen from the front13of the vehicle in the direction of the rear window7. In this exemplary embodiment, said flow ramp15is formed on the guide element9. The flow ramp15is in alignment with a so-called roofline16as far as a ramp edge17. Downstream of the ramp edge17, the flow ramp15is located beneath the roofline16, wherein, as seen in cross section, seeFIG. 2, it extends concavely as far as the entry opening11. It would also be possible for the flow ramp15to be of rectilinear design and/or to be formed likewise on a roof18of the motor-vehicle body2.

The air-directing element8having a first width B1is arranged such that its upper surface19, which faces toward the surroundings, is approximately parallel to a virtual extension of the roofline16, wherein the virtual extension of the roofline16is located at a lower level, in the direction of a floor20of the vehicle, than the upper surface19. In a second exemplary embodiment, as is illustrated inFIG. 3, the upper surface19is positioned beneath the virtual extension of the roofline16. This corresponds to the air-directing element8being positioned in a manner which yet further reduces the drag of the motor-vehicle body2.

In the exemplary embodiments illustrated, as are illustrated inFIGS. 1 to 11, the air-directing element8is connected rigidly to the guide element9. It would likewise be possible for the air-directing element8also to be connected to the guide element9such that it can be moved in part or in full, this making it possible to achieve further adaptation of the lift or downforce.

The upper surface19of the air-directing element8is essentially of planar design. The air-directing element8has a more or less triangular cross section corresponding to a wing, wherein the upper surface19and a lower surface21, facing away from the upper surface19, of the air-directing element8, have a joint entry edge23at the entry opening11. On that side of the air-directing element8which faces away from the entry edge23, the upper surface19is connected to the lower surface21with the aid of a side surface26of the air-directing element8.

The flow channel10, which is formed between the air-directing element8and the guide element9, is L-shaped, with the aid of the side surface26, along the longitudinal axis14, in the flow direction of the flow arrow22, and is designed so that the air flowing through the flow channel10flows out essentially perpendicularly to the upper surface19, wherein the upper surface19is part of an outer contour25of the air-directing element8. This means, in other words, that the air-directing device4is designed so that the air flowing through the flow channel10is guided thereby out of the exit opening12essentially perpendicularly to an outer contour25of the air-directing element8.

In order to avoid stalls in flow and burbling during deflection of the air which enters into the flow channel10and is deflected into the flow channel10, the entry edge23and also a deflecting edge24of the air-directing element8, said deflecting edge being formed between the lower surface21and the side surface26, are rounded.

Starting from the entry opening11, the flow channel10tapers in the longitudinal direction in the direction of the exit opening12as far as deflecting edge24and, for example in dependence on the type of engine in the motor vehicle1, it can have a greater or smaller, or variable, flow cross section in its channel-outflow portion27, which is formed between the deflecting edge24and the exit opening12.

Starting from the roof18, the channel-inflow portion28of the flow channel10is inclined in the direction of the rear window7in relation to the floor20of the vehicle, wherein, starting from the deflecting edge24, the channel-outflow portion27extends away from the floor20of the vehicle in the direction of the exit opening12, so that the air can be directed out of the flow channel10at an angle, as seen in relation to a virtual horizontal parallel to the floor20of the vehicle, and in relation to an associated virtual vertical, which is acute in relation to said virtual vertical.

FIG. 4illustrates a detail of a longitudinal section through a third exemplary embodiment of the air-directing device4, wherein the detail corresponds to that region of the air-directing device4which is indicated by IV inFIG. 2. For improved guidance of the air stream, the guide element9has a projecting portion29in relation to the upper surface19of the air-directing element8. This means, in other words, that the projecting portion29is formed between a virtual extension of an outer surface30of the guide element9, said outer surface delimiting the exit opening12and being inclined downward preferably away from the air-directing element, and the upper surface19, wherein the upper surface19is arranged between the projecting portion29and the channel-inflow portion28. This means, in other words, that the outer surface30has at least its first separation edge31at the exit opening12, said separation edge delimiting the flow channel10, at a higher level than a second separation edge32of the air-directing element8, said second separation edge delimiting the exit opening12.

The guide element9has a second width B2, which is greater than the first width B1, wherein the exit opening12extends essentially over the second width B2. In order to create the flow ramp15upstream of the entry opening11, a first length L1of the air-directing element8is rendered smaller than a second length L2of the guide element9.

In the first and second exemplary embodiments, the air-directing element8has an essentially rectilinear entry edge23, wherein the second separation edge32of the air-directing element8is likewise of essentially rectilinear design.

In a fourth exemplary embodiment according toFIGS. 6 and 7, and in a fifth exemplary embodiment according toFIGS. 8 to 11, the air-directing element8is designed in the form of a shaped element. This means, in other words, that the air-directing element8, in particular the entry edge23and/or the second separation edge32, is not an essentially rectilinear edge. Therefore, for example the air-directing element8of the air-guide device4of the fourth exemplary embodiment has the entry edge23with a first arcuate contour33, a second arcuate contour34and a third arcuate contour35, wherein the entry edge34is designed symmetrically in relation to the longitudinal axis14. The first contour33and the second contour35are designed in an axially symmetrical manner or mirror-symmetrical manner in relation to the longitudinal axis14, whereas the second contour34differs from the other two contours33,35. It would likewise be possible for all the contours33,34,35to differ from one another, i.e. for them also to be designed in a manner in which they are not axially symmetrical.

The air-directing element8is fixedly connected to the guide element9with the aid of its outer edges37, which extend in the longitudinal direction and between the entry edge23and the second separation edge32, such that the flow channel10is in the form of a channel which is delimited on either side and extends along the longitudinal axis14, this resulting in the formation of a channel chamber36through which flow can take place in the direction of the longitudinal axis14.

The flow channel10of the fourth exemplary embodiment is subdivided into three channel chambers36in the transverse direction, i.e. over its extent along the first width B1of the air-directing element8. This means, in other words, that the flow channel10has three channel chambers through which flow can take place in the direction of the longitudinal axis14. It would likewise be possible for there to be just two chambers36or more than three chambers36. The three channel portions36are formed with the aid of two supports38, which extend in the direction of longitudinal axis14.

The air-directing element8of the fifth exemplary embodiment likewise has three channel chambers36, wherein both the entry edge23and the second separation edge32have a contour which differs significantly from a rectilinear contour, wherein they are of aerodynamically optimized design in order to create high-level downforce and a low drag coefficient of the motor vehicle1.

The air-directing device4according to the fifth exemplary embodiment is illustrated in a side view inFIG. 11, wherein the longitudinal extent of the flow channel10can be seen to very good effect in this illustration. This illustration particularly shows that, starting from a typical roof spoiler beneath which flow cannot take place, and of which the upper spoiler surface, which faces toward the surroundings, is usually in alignment with the roofline16, the air-directing device4according to the invention can be realized in a cost-effective manner by the formation of a flow bed40of the flow channel10with the aid of material removal or material reduction.

The distance between the entry edge23and the ramp edge17is preferably at least double the size of the distance between the air-directing element8and the guide element9. This means that for example the distance between the entry edge23and the ramp edge17should be selected to be a value of 50 mm, wherein the distance between the air-directing element8and the guide element9should be selected to be a value ranging from 10 to 20 mm. In adaptation to the distance-value examples, the projecting portion29has a preferred value ranging between 2 and 5 mm.

As illustrated, in particular, inFIG. 2, during operation of the motor vehicle1in the direction of travel FR, the air flows, with the aid of the air-directing device4according to the invention, with barely any disturbance over the roof18and is drawn downward into the flow channel10with the aid of the flow ramp15, and is therefore divided up into two sub-streams, wherein the one sub-stream flows over the upper surface19and the other sub-stream flows through the flow channel10. This gives rise, in dependence on the speed of the motor vehicle1, to the upper surface19being subjected to a certain compressive force by the sub-stream flowing over it, and the downforce being the result of said compressive force.

A resultant force in the flow channel10, which is generated on account of the air flowing out of the exit opening12more or less perpendicularly to the upper surface19, further increases the downforce since this sub-stream, with a corresponding force component, corresponds to an effect of a conventionally movable spoiler, beneath which flow cannot take place, when the spoiler is in position.

The air-directing element8and/or the guide element9can be produced from plastic, carbon fiber or the like. It is also possible for them to have the same or different coloring and/or surface configuration.

The air-directing device4according to the invention is not restricted to use for one particular type of vehicle body. It is thus possible for it to be used, as illustrated inFIG. 1, on a so-called SUV body and also, for example, on a so-called coupe body as well as, for example, on a so-called station-wagon body.

LIST OF REFERENCE SIGNS