Air guiding device and method for operating the same

Abstract

An air-guiding device which is arranged in a top rear region of a vehicle and includes an air-guiding element which is shiftable from a retracted inoperative position to an extended operating position, wherein, in both positions, the air-guiding element serves for guiding air in the rear region of the motor vehicle. At least one propeller of the air-guiding device which, together with the air-guiding element, is shiftable between the retracted and extended positions, wherein the propeller, in the extended operating position, is fixable in a first operating state, wherein the at least one propeller, in the extended operating position, is operable in a second operating state in order to produce a throughflow in the direction of travel, and wherein the at least one propeller, in the extended operating position, is operable in a third operating state in order to produce a throughflow opposed to the direction of travel.

Claims

1. An air-guiding device for a passenger vehicle, and which is arranged in a top rear region of the vehicle, comprises: an air-guiding element which is shiftable from a retracted inoperative position, in which the air-guiding element is integrated in a surface-flush manner into a shape profile of the rear region, into an extended operating position, wherein, both in the retracted inoperative position and in the extended operating position, the air-guiding element serves for guiding air in the rear region of the motor vehicle, wherein the air-guiding element is assigned at least one propeller which, together with the air-guiding element, is shiftable between the retracted inoperative position and the extended operating position, wherein the or each propeller, in the extended operating position, is fixable in a first operating state, wherein the or each propeller, in the extended operating position, is operable in a second operating state in order to produce a throughflow in the direction of travel, and wherein the or each propeller, in the extended operating position, is operable in a third operating state in order to produce a throughflow opposed to the direction of travel.

2. The air-guiding device as claimed in claim 1, wherein whenever the or each propeller, in the extended operating position of the air-guiding element, is fixed in the first operating state, a drag of the vehicle is reduced and a rear-axle downforce of the vehicle is increased in comparison to the retracted inoperative position.

3. The air-guiding device as claimed in claim 1, wherein whenever the or each propeller, in the extended operating position, is operated in the second operating state, a drag of the vehicle is further reduced and a rear-axle downforce of the vehicle is further increased in comparison to the first operating state.

4. The air-guiding device as claimed in claim 1, wherein whenever the or each propeller, in the extended operating position, is operated in the third operating state, a drag of the vehicle is increased and a rear-axle downforce of the vehicle is reduced in comparison to the first operating state.

5. The air-guiding device as claimed in claim 1, wherein the or each propeller, in the extended operating position, is operated as a generator in the second operating state.

6. The air-guiding device as claimed in claim 1, wherein the or each propeller, in the extended operating position, is operated as a motor in the third operating state.

7. The air-guiding device as claimed in claim 1, wherein the or each propeller is embodied as an axial turbine.

8. The air-guiding device as claimed in claim 1, wherein the or each propeller is embodied as a radial turbine.

9. A method for operating the air-guiding device as claimed in claim 1, wherein whenever the or each propeller, in the extended operating position, is fixed in a first operating state, a drag of the vehicle is reduced and a rear-axle downforce of the vehicle is increased in comparison to the retracted inoperative position, whenever the or each propeller, in the extended operating position, is operated in a second operating state in order to produce a throughflow in the direction of travel, the drag of the vehicle is further reduced and the rear-axle downforce of the vehicle is further increased in comparison to the first operating state in the extended operating position, whenever the or each propeller, in the extended operating position, is operated in a third operating state in order to produce a throughflow counter to the direction of travel, the drag of the vehicle is increased and a rear-axle downforce of the vehicle is reduced in comparison to the first operating state in the extended operating position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred developments of the invention emerge from the dependent claims and from the description below. Exemplary embodiments of the invention, without being restricted thereto, are explained in more detail with reference to the drawing, in which:

(2) FIG. 1 shows a detail from a rear region of a motor vehicle with a first air-guiding device according to aspects of the invention in an extended operating position.

(3) FIG. 2 shows a detail from a rear region of a motor vehicle with a second air-guiding device according to aspects of the invention in an extended operating position.

(4) FIG. 3 shows a radial propeller of the air-guiding device.

DETAILED DESCRIPTION OF THE INVENTION

(5) The air-guiding device of a motor vehicle is arranged in a top rear region of the vehicle and comprises a shiftable air-guiding element.

(6) FIG. 1 shows a first exemplary embodiment of an air-guiding device 10 according to aspects of the invention with a shiftable air-guiding element 11, wherein the air-guiding device 10 is arranged in a top rear region 12 of the motor vehicle. The air-guiding element 11 of the air-guiding device 10 is shiftable between a retracted inoperative position and an extended operating position, namely, in FIG. 1, in the direction of the arrow 13 shown there, wherein, in the retracted inoperative position, the air-guiding element 11 is integrated in a surface-flush manner into the shape profile of the rear region 12 of the motor vehicle.

(7) Both in the retracted inoperative position and in the extended operating position, the air-guiding element 11 of the air-guiding device 10 serves for conducting an air stream in the rear region of the motor vehicle.

(8) Within the meaning of the invention present here, the air-guiding element 11 of the air-guiding device 10, which air-guiding element is shiftable between the retracted inoperative position and the extended operating position, is assigned at least one propeller 14.

(9) In the exemplary embodiment of FIG. 1, the air-guiding element 11 is assigned a plurality of propellers 14, namely a total of six propellers 14, which are embodied as axial turbines or axial propellers.

(10) The propellers 14, together with the air-guiding element 11, are shiftable between the extended operating position and the retracted inoperative position.

(11) In the exemplary embodiment of FIG. 1, the propellers 14, in the extended operating position shown in FIG. 1, are operable in different operating states. Thus, in a first operating state of the extended operating position, the propellers 14 can be fixed in the extended operating position. In the extended operating position, the propellers 14 can be operated in a second operating state in order to produce a throughflow in the direction of travel of the vehicle. The flow direction is illustrated in FIG. 1 by means of an arrow 15. Furthermore, it is possible for the propellers 14, in the extended operating position, to be operated in a third operating state in which said propellers serve for producing a throughflow opposed to the direction of travel.

(12) Whenever the propellers 14 of the air-guiding device 10 of FIG. 1, in the extended operating position of the air-guiding element 11 in FIG. 1, are fixed in the first operating state, a drag value of the motor vehicle is reduced and a rear-axle downforce of the vehicle or a coefficient of rear-axle downforce is increased, to be precise in comparison to the retracted inoperative position of the air-guiding device 10.

(13) Whenever the propellers 14, in the extended operating position, are operated in the second operating state in which said propellers produce a throughflow in the flow direction (i.e. (in) the direction of travel) or with the wind direction, the drag value is further reduced and the coefficient of rear-axle downforce or the rear-axle downforce is further increased in comparison to the first operating state of the extended operating position. In the second operating state in the extended operating position, the propellers 14 are then operated in a “tension direction”, and a buildup of pressure upstream of the air-guiding device 10 drops. The propellers 14 can be used in this case in the generator mode of same to produce electrical energy and to charge an electrical energy accumulator.

(14) Whenever the propellers 14, in the extended operating position, are operated in the third operating state in which said propellers produce a throughflow counter to the direction of travel, the drag of the vehicle is increased and the rear-axle downforce of the vehicle or the coefficient of rear-axle downforce is reduced in comparison to the first operating state. In the third operating state in the extended operating position, the propellers 14 are operated in the “pressure direction”, and a greater buildup of pressure is produced upstream of the air-guiding device 10 than in the first operating state in the extended operating position. The propellers 14 are preferably driven here as a motor.

(15) FIG. 2 shows a further exemplary embodiment of an air-guiding device 10 according to aspects of the invention which only differs from the exemplary embodiment of FIG. 1 in that the propellers 14 assigned to the shiftable air-guiding element 11 are not embodied as axial propellers, but on the contrary as radial propellers or radial turbines.

(16) FIG. 3 shows a radial propeller 14 of this type in longitudinal section. In the case of the axial propellers 14 of FIG. 1, the axes of rotation of same run substantially in the direction of travel or the throughflow direction of same. In the case of the radial propellers 14 of FIGS. 2 and 3, the axes of rotation of same run substantially transversely with respect to the direction of travel and therefore in the throughflow direction of same.

(17) With the air-guiding device 10 according to aspects of the invention, it is accordingly possible, in the extended operating position of the air-guiding element 10 and therefore in the extended operating position of the propellers 14 which are shiftable together with the air-guiding element 11, firstly to influence the drag of the motor vehicle in a targeted manner and secondly to provide downforce to a greater or lesser degree at the rear axle of the motor vehicle.

(18) Accordingly, it is within the meaning of the invention present here to propose an air-guiding device 10 of a vehicle, which has an air-guiding element 11 which is shiftable between the retracted inoperative position and the extended operating position, wherein, in the retracted inoperative position, the air-guiding element 11 is integrated in a surface-flush manner into the shape profile of the rear region of the motor vehicle.

(19) The shiftable air-guiding element 11 is assigned propellers 14 which are shiftable together therewith and, in the extended operating position, can be operated in different operating states, namely in a first operating state of the extended operating position, in which said propellers are fixed and accordingly do not rotate, in a second operating state of the extended operating position, in which said propellers produce a throughflow in the direction of travel, and in a third operating state of the extended operating position, in which said propellers provide a throughflow opposed to the direction of travel. Via said operating states in the extended operating position of the air-guiding device, the drag and the rear-axle downforce, and therefore the aerodynamic properties of the vehicle, can be advantageously influenced; furthermore, electrical energy can optionally be produced.