DE102008013336B4 - Motor vehicle with an active ventilation flap - Google Patents

Abstract

Motor vehicle with at least partially enclosing outer surfaces with at least one ventilation opening (10) provided therein for cooling and / or ventilation, which is arranged in a front engine compartment area frontally, laterally, above and / or below the body and / or in a rear area of the body and at least one ventilation opening (10) with at least one cover flap provided for opening and closing is provided for ventilating and / or venting at least one of the units belonging to the drive, air conditioning or braking devices by sucking in or blowing in outside air or air sucked out by the airstream (18) and closes the ventilation opening (10) in such a way that the outer surface of the lid flap (18) forms an aerodynamically favorable surface shape with the adjacent outer surfaces of the vehicle or its parts, the lid flap (18) is equipped with a drive, characterized in that the Drive of the cover flap (18) is designed with at least one material-active actuator (22, 24), the active actuator (22, 24) is a thermally acting element, such as a bimetallic element, expansion thermocouple, shape memory element, the active actuator (22, 24) is electrically heated with the aid of an additional heating element.

Description

The invention relates to motor vehicles with at least one ventilation flap with the features mentioned in the preamble of claim 1.

It is known that the waste heat generated in the combustion process in a vehicle engine is dissipated via a water cooling system. The heated cooling water is cooled with the air flow from the driving wind and additionally with an air blower. In the same way, auxiliary units such as oil coolers, air conditioning condensers and air conditioning compressors are cooled by the flow of cooling air.

In addition, the engine compartment is forced to be cooled via, for example, permanently open ventilation openings and nozzles located in the underbody paneling of the engine compartment. In addition, such nozzles are also provided for permanent cooling of the brakes in the underbody and in the area of the wheel arches.

In most cases, this passive unit cooling is designed for maximum engine or transmission load (trips in hot countries, trailer operation, mountain passes) or for maximum brake loads (repeated brief braking from maximum speed, downhill passes with trailer operation and permanent brakes). In many other partial load conditions, the inflowing cooling air flow is not required or even not desired (for example with a cold start, but also with the predominant proportion in standard driving mode).

In addition, the cooling air flowing into the engine compartment results in an increase in air resistance and thus a deterioration in the overall vehicle aerodynamics. As is well known, air resistance increases with the square of the driving speed and has a negative effect on fuel consumption and thus C02 emissions, which means that even small impairments become noticeable with increasing driving speed. Active ventilation flap actuation is therefore desirable, which only directs a flow of cooling air into the engine compartment or to the brakes when the cooling of the engine, transmission and auxiliary units or brakes is essential. Otherwise, the ventilation flaps should be closed as completely as possible. As a result, the motor is not additionally cooled as long as it is in the cold start phase and the brake cooling will not unnecessarily generate air resistance. In addition, the sound emissions from the engine compartment to the outside are reduced by the closed ventilation flaps. Even with standard driving, the additional air flow for cooling the aggregates is not required in most cases.

In aircraft construction, a so-called nozzle cooler is known as a heat exchanger, in which the cooler generates a thrust force by heating the air. The effect is based on the fact that the air is introduced into the cooler through a relatively small gap in the direction of movement, where it is heated and expanded, and then leaves the cooler again through a nozzle against the direction of movement. This does not generate any thrust when the vehicle is stationary. This cooling principle was used in airplanes with water-cooled engines. The principle of the nozzle cooler was patented by Hugo Junkers in 1915. An engine cover for aircraft with radial engines that works on the same principle is called a NACA hood and the nozzle cooler is called NACA nozzles.

Conventional drives (electric motor, electromagnetic, drive via vacuum boxes or thermal wax drives) for a flap are often difficult or impossible to install for reasons of installation space.

In EP 1 337 757 B1 active valves for microfluidics are described, which are driven by an element made of a shape memory material or electroactive polymer.

EP 1 169 591 B1 describes a fuel injection valve that is switched via a shape memory element.

In DE 3405609 A1 describes a ventilation flap in a microwave oven, which is actuated by a shape memory spring.

EP 1 161 204 B1 describes the special design of a shape memory spring that is implemented in blood vessels in a medical application.

In EP 1 219 313 A1 describes the use of a valve made of a magnetically driven shape memory alloy integrated in a flexible hose.

A sunroof opening in the roof of a vehicle has a cover that can be slid and set up at an angle and is operated mechanically or electromechanically. In most cases, the opening and closing of the sliding roof cover is triggered manually by a user from inside the vehicle. The sunroof opening is used to supply fresh air and is usually closed when the user feels disturbed by the airstream or wind noise at increasing speed or if he deliberately wants to reduce the air resistance, which is one caused open sunroof opening. An additional wind-deflecting flap is set up at an angle against the wind when the sliding roof is open.

DE 16 30 287 A discloses a sunroof flap which is pneumatically driven by negative pressure or positive pressure to reduce the closing and opening forces.

Also known is a manually operated summer / winter flap which, for example, switches the air supply to the engine's air intake in the cold season from direct flow air to an air supply from the engine compartment. Although such a flap creates a desired warmer microclimate for the internal combustion engine during the cold season, it is not arranged on an outer surface of the vehicle, but mostly behind a front air grille, so that its opening position has little or no effect on the overall vehicle aerodynamics.

Likewise, none of the patent literature sources listed above offers a solution aimed at improving the aerodynamics of the vehicle.

US 2007/0199751 A1 shows a motor vehicle with at least partially enclosing outer surfaces with at least one ventilation opening provided for cooling and / or ventilation.

The at least one ventilation opening is equipped with at least one cover flap provided for opening and closing.

DE 199 04 515 A1 discloses a device for cooling a temperature-loaded unit. A pressure-dependent opening air flap is provided, the start of which can be changed by an elastic element.

In the following, the term aggregate is understood to mean the combination of several devices, machines or apparatuses to fulfill a certain technological function. The aggregate differs significantly from a single part or tool. With the link, the technological function of the individual device in the unit is canceled; it is rather subsumed under the technological function of the unit.

The invention is based on the object of creating a vehicle with an active ventilation flap that can be variably actuated in a simple manner.

The object is achieved according to the invention by a motor vehicle with an active ventilation plate having the features mentioned in claim 1.

Because the drive of the cover flap is designed with at least one material-active actuator, the active actuator is a thermally acting element such as a bimetallic element, expansion thermocouple, shape memory element or the like and the active actuator is electrically heated with the help of an additional heating element is, it is advantageously possible to variably set a switching temperature of the drive of the cover flap.

With configurations described below, the thermocouples can easily be actuated by the heat of the surrounding air, for example in the engine compartment or by heating with an electric current, and are inexpensive to manufacture, with the active actuating element being generated by the heat generated by the vehicle units and / or is actuated directly thermophysically by the air temperature of the airstream air flow and the active actuating element is electrically heated with the aid of an additional heating element.

In a further development of the present invention, a wire element or a surface element is used as the additional, electrically energized heating element. Wire is the simplest construction tool imaginable and is therefore easy to process. For actuating elements that are active in the form of a strip or plate, it can be advantageous to use a thin or thin-layer heating film for the additional, electrically energized heating element.

In a further embodiment of the present invention, the active actuating element for generating a heating output can be directly electrically energized in a particularly advantageous manner.

In a further preferred embodiment of the present invention, the active actuating member can have at least two material-active elements which are arranged essentially close to one another or one above the other and which can each be electrically energized separately to generate a heating power. As a result, the material-active actuating element can act selectively in different directions. With a corresponding number of the individual actuating elements, more than two different actuating directions can be achieved. A different effective force can also be specified as a result. Furthermore, in yet another preferred development of the present invention, the material-active elements can be designed as shape memory elements, each with a differently preset switching temperature. This enables the lid flap to be opened / closed in stages.

In a further preferred embodiment of the present invention, the cover flap, which is pivotably mounted on an edge of a surface belonging to the vehicle, is mounted in a swivel hinge or a bending hinge in the longitudinal or transverse direction or in a direction in between with respect to the straight-ahead direction of travel of the vehicle.

In a preferred embodiment of the present invention, the material-active actuating element can additionally and simultaneously be used as a sensor element and supply a measurement signal derived from a physical variable to a controller. This can be, for example, temperature, air pressure or a vibration signal.

The material-active actuating element made from a shape memory material can preferably be designed as a wire, several wires, a meandering wire, a plate and / or a band in order to be able to specify a desired force effect and / or change length.

The actuating member of the cover flap made from the shape memory material preferably has a predetermined effective temperature setting. In contrast to bimetallic active materials, which have a continuous thermal change in length, the shape memory materials can achieve a relatively narrow switching temperature.

The cover flap can be designed as either actively closing or actively opening. Furthermore, the ventilation opening closed with the cover flap can be arranged in the direction against the airflow or in the direction facing away from the airflow.

In a further preferred embodiment of the present invention, the pressure force of the head wind is used as an actuating force that closes or opens the cover flap. In this way, an air pressure and thus a speed-dependent cover flap control can be implemented.

The cover flap is preferably biased against the acting force with at least one resilient element. The surface of the cover flap can be designed both as a rigid flap surface and as a flexible flap surface.

In a further preferred embodiment of the present invention, the cover flap is equipped with at least one element which engages in at least one step which corresponds to an opening step of the cover flap and which can be unlocked. As a result, a material-active element does not need to be continuously energized with electrical energy in its active position generated by an electrical signal, because the position reached is retained by latching. To release from such a locked position, the electrical signal is applied again and an unlocking device is actuated.

For this purpose, in a further preferred embodiment of the present invention, the locking element can be designed as a micro-toothed hinge with a defined predetermined overcoming force as a mechanical ratchet with automatic locking.

In yet another preferred embodiment of the present invention, the cover flap is equipped with a displaceable mass which is arranged in a cavity provided in the cover flap. This allows the mechanical opening / closing behavior of the cover flap to be changed depending on the situation.

The spring pretensioning the cover flap can be made from a material-active element such as a shape memory element and the spring constant of the pretensioning spring can be changed by changing the parameters of the material-active element. As a result, only the physical properties of the material-active element are changed, whereby a different, for example situation-adapted opening / closing behavior of the cover flap can be achieved.

The spring biasing the cover flap can advantageously be arranged in a series and / or parallel connection of passive springs.

In yet another preferred embodiment of the present invention, the bending hinge of the cover flap is used as a sheet metal strip with an element that is active in the material.

In yet another preferred embodiment of the present invention, at least one piezo element arranged in the hinge and excited by a vibration signal in a highly dynamic manner is used as the actuating element. This can act, for example, on a locking pinion which is arranged and designed as a drive shaft.

A transmission element can be arranged between an actuating member and the cover flap or the vehicle surface, which is designed, for example, as a rope or rod and only transmits the actuating force of the actuating member.

According to a partial aspect of the present invention, the lid flap is only biased towards the closed position with a spring element as an alternative to an active electromechanical drive, with its opening direction aligned in the direction of travel and an additional inclined surface is formed on the front section of the lid flap, which the dynamic pressure of the Absorbs airflow.

The spring element is preferably designed as a spiral, leg or spiral spring and has a predetermined spring characteristic. Even more preferably, the spring element can be formed by the surface of the cover flap, which for this purpose is formed from a resilient material.

According to a further embodiment of the present invention, the spring element formed by the surface of the cover flap is provided with a “cracking frog effect” and thus has a stable and a metastable state. As a result, the cover flap is suddenly opened and closed when the air pressure force generated by the airflow exceeds or falls below a correspondingly preset amount.

In a preferred embodiment of the present invention, an elastic element covering at least one surface section is arranged on the surface of the lid flap and is firmly connected to the surface of the lid flap. As a result, undesired natural vibrations of the cover flap are damped and, when the cracking frog effect is used, the associated clicking noise is suppressed at the same time. It also muffles drumming noises that can be caused by falling rocks. The elastic element can for example be made of rubber or an elastomer. Further preferred refinements of the invention result from the other features mentioned in the subclaims.

• 1A eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch vorbeiströmenden Fahrtwind nach Stand der Technik;
• 1 B eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind nach Stand der Technik;
• 1C eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind nach Stand der Technik;
• 1D eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den vorbeiströmenden Fahrtwind nach Stand der Technik;
• 2 eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind mit erfindungsgemäßer Deckelklappe in einer ersten Ausgestaltung;
• 3 eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind mit erfindungsgemäßer Deckelklappe in einer zweiten Ausgestaltung;
• 4 eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind mit erfindungsgemäßer Deckelklappe in einer dritten Ausgestaltung;
• 5 eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind mit erfindungsgemäßer Deckelklappe in einer vierten Ausgestaltung;
• 6 eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind mit erfindungsgemäßer Deckelklappe in einer fünften Ausgestaltung;
• 7 eine schematische Darstellung einer unter einem Motorraum eines Fahrzeugs angeordneten Lüftungsöffnung mit Entlüftung durch den in die Belüftungsöffnung einströmenden Fahrtwind mit erfindungsgemäßer Deckelklappe in einer sechsten Ausgestaltung;
• 8 eine schematische Darstellung einer an einem Fahrzeug angeordneten erfindungsgemäßen Deckelklappe in einer siebten Ausgestaltung der Erfindung und
• 9A, 9B eine schematische Darstellung einer an einem Fahrzeug angeordneten und 9C erfindungsgemäßen Deckelklappe in einer achten Ausgestaltung der Erfindung und
• Figuren eine schematische Darstellung einer an einem Fahrzeug angeordneten 10A, 10B erfindungsgemäßen Deckelklappe in einer neunten Ausgestaltung der Erfindung.

The invention is explained below in exemplary embodiments with reference to the accompanying drawings. Show it:

• 1A a schematic illustration of a ventilation opening arranged under an engine compartment of a vehicle with ventilation by means of the airstream flowing past according to the prior art;
• 1 B a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening according to the prior art;
• 1C a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening according to the prior art;
• 1D a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation by the airstream flowing past according to the prior art;
• 2 a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening with a cover flap according to the invention in a first embodiment;
• 3 a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening with a cover flap according to the invention in a second embodiment;
• 4th a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening with a cover flap according to the invention in a third embodiment;
• 5 a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening with a cover flap according to the invention in a fourth embodiment;
• 6th a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening with a cover flap according to the invention in a fifth embodiment;
• 7th a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle with ventilation through the airflow flowing into the ventilation opening with a cover flap according to the invention in a sixth embodiment;
• 8th a schematic representation of a cover flap according to the invention arranged on a vehicle in a seventh embodiment of the invention and
• 9A , 9B a schematic representation of a cover flap arranged on a vehicle and according to the invention in an eighth embodiment of the invention and FIG
• Figures show a schematic representation of a cover flap 10A, 10B according to the invention arranged on a vehicle in a ninth embodiment of the invention.

1A to 1D show a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle 10 according to the state of the art.

In 1A and 1D the wind flows past a ventilation opening facing away from it 10 and creates a suction effect by which the warm air is sucked out of the engine compartment.

In 1B and 1C is the wall 14th the air scoop aligned in the direction of travel so that the opening 10 is arranged directly in the incoming airstream. With this arrangement, part of the driving air flows into the opening 10 and is possibly led out again to the outside, for example somewhere else (not shown).

In all cases described, such ventilation openings cause 10 According to the state of the art, a not inconsiderable air resistance and are possibly overdimensioned in cold running phases and during normal operation and thus contribute to excessive cooling of the engine and vehicle assemblies, whereby energy is lost and the cold running phases take longer than necessary.

2 shows a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle 10 with ventilation through the into the ventilation opening 10 inflowing airflow with a cover flap according to the invention 18th in a first embodiment.

The ventilation opening 10 is aligned here against the wind marked with an arrow, but can be arranged in another embodiment exactly the other way around as below 1A to 1D has been described.

An actuator 20th acts on the lid flap 18th for example via a transmission element 16 one that can be designed both as a tensile cable and a rod that can be subjected to tensile and compressive loads. The lid flap 18th is designed as a rigid surface in a hinge 13th rotatable on an underbody surface 12th is stored.

In this embodiment, the ventilation flap, after it has been opened a little, can be pushed down by the air pressure of the airstream. The cover flap can also 18th be biased by a spring, not shown, which can be designed as an arbitrarily designed tension, compression or leg spring and / or the like.

3 shows a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle 10 with ventilation through the into the ventilation opening 10 inflowing airflow with a cover flap according to the invention 18th in a second embodiment.

Here is the arrangement of the ventilation flap 18th on the vehicle floor 12th essentially the same as in 2 described, however, is the drive or the actuator 20th in relation to the lid flap on the other side of the underbody surface 12th arranged and thereby also the transmission element 16 at a shallower angle on the lid flap 18th engaged. This may be necessary due to the available installation space.

The transmission element 16 can in this case be designed as a cable, which is operated by an electromechanical actuator, for example 20th , for example a geared electric motor, is wound and unwound. In another embodiment, the transmission element 16 itself a material-active actuator 20th be, for example, a thermally adjustable length of wire rope, which instead of the actuator shown 20th has only one fastening or, in a further embodiment of the invention, additionally with an electromechanical actuator 20th is driven.

The lid flap 18th is preferably pretensioned in the opening direction by a tension spring, compression spring or leg spring or the like (not shown).

The control of the opening and closing of the lid flap 18th takes place, for example, with the help of an electronic control (not shown), which detects the engine compartment temperature or the temperature of another unit, for example, and controls the supply of fresh air as a function of this. Alternatively, such an electronic control can be dispensed with entirely in a further embodiment in which the in the ventilation opening 10 incoming outside air and the air circulating in the engine compartment directly on the as a material-active actuator 20th executed cable 16 acts thermally. In the cold running phase, the air in the engine compartment is cold, so the cable pull 16 contracts and the lid flap 18th closes. If the air flowing into the cable becomes warmer, the expanding cable opens the cover flap 18th and allows colder air to flow in and vice versa.

4th shows a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle 10 with ventilation through the into the ventilation opening 10 inflowing airflow with a cover flap according to the invention 18th in a third embodiment of the present invention.

In an arrangement that is essentially the same as that previously described is a cover flap 18th with a material-active actuator 22nd driven, which is made for example from a shape memory material with a predetermined switching temperature. The control of this material-active actuator 22nd can be carried out, as previously described, by a direct thermal effect of the air flow and by an electronic control system. In the latter case, in an advantageous embodiment of the invention, the material-active actuating element 22nd be heated in a controlled manner by a heating element (not shown), for example one made of wire or a thin film, or alternatively serve as the heating element itself, in that electrical current is passed through the material-active actuating element 22nd is passed through for heating. In this case the material-active actuator is 22nd to insulate against short circuit with adjacent parts.

5 shows a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle 10 with ventilation through the into the ventilation opening 10 inflowing airflow with a cover flap according to the invention 18th in a fourth embodiment of the invention.

In contrast to the configurations described above, the cover flap 18th produced here as a flexible surface from a flexible material. This flexible surface can itself be designed as a pretensioned spring element or can be pretensioned by a spring (not shown), for example in the opening direction. As in 2 for example, actuates an actuator 20th via a transmission element 16 the lid flap 18th . This eliminates the need for an articulated hinge for the rotatable mounting of the cover flap 18th and instead a bending hinge is used, which extends essentially, for example, over the entire length of the cover flap 18th extends.

6th shows a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle 10 with ventilation through the into the ventilation opening 10 inflowing airflow with a cover flap according to the invention 18th in a fifth embodiment of the invention.

It is an embodiment of the present invention with a flexible top flap 18th as in 5 described, which is driven by a cable drive as in 3 is driven. The cable pull 16 can cross the surface of the cover flap as shown and pull it from the outside in the direction of opening, so that in this case the cover flap 18th can be biased towards closing. With regard to the control, all of the types of control described can also be used in this embodiment.

7th shows a schematic representation of a ventilation opening arranged under an engine compartment of a vehicle 10 with ventilation through the into the ventilation opening 10 inflowing airflow with a cover flap according to the invention 18th in a sixth embodiment of the present invention.

The lid flap 18th is here as in 5 and 6th previously described designed as a flexible surface, without a hinge on the underbody surface 12th is grown.

The operation of the lid flap 18th takes place by means of an actuating element that is active on the material 24 , which is similar to the material-active actuator 22nd in 4th directly on the inner surface of the lid flap 18th is attached and acts on this directly and is designed to be flexible together with her.

As an active material, for example, shape memory material or a bimetallic material come into question, that is to say a thermally acting element, for example composed of two superposed links. The control can be carried out in one of the ways already described, for example.

8th shows a schematic representation of a cover flap according to the invention arranged on a vehicle 18th in a seventh embodiment of the invention in a plan view.

Here is the cable pull 16n between a front retaining element 26A and a rear holding element 26B spanned several times in a meandering manner at the intended reversal points (not shown). As a result, the possible force that can be achieved by a cable pull is the number n of the individual cable pulls 16n elevated. The cable can therefore be made from a relatively thin wire.

9A , 9B and 9C show a schematic representation of a cover flap according to the invention arranged on a vehicle 18th in an eighth embodiment of the invention.

The cover flap is in this embodiment 18th waiving additional electromechanical actuation units set up in such a way that it is actuated by the airflow. For this purpose, the cover flap with the opening facing the direction of the head wind, as in 1C shown aligned and preferably at its leading edge portion with an additional sloping surface 19th equipped, which thereby forms a pressure lip. This pressure lip 19th has such a predetermined shape and size that the airstream generates enough pressure force from a certain speed reached to the lid flap 18th against the spring force of a spring element 17th , which is designed here as a tension spiral spring, for example. The spring element 17th tensions the cover flap with a predefined force and specified spring characteristics 18th to the closed position. The degree of opening of the lid flap 18th is proportional to the speed of the vehicle and the spring force of the spring element 17th one, so that at higher speed an increasingly larger opening 10 the lid flap 18th a more intensive ventilation of the behind the opening 10 arranged interior, for example the engine compartment, allows. Since a motor also delivers more power at a higher speed, more waste heat is produced as a result, so that the speed-dependent ventilation according to the invention also provides a very inexpensive and effective remedy for this. The pressure lip 19th has relatively small dimensions and therefore causes one, only at low speed with the lid closed 18th , effective low air resistance.

The lateral areas of the cover flap are preferred 18th with side locking elements 21a , 21b , 21c , 21d closed so that the incoming airstream is better bundled. In this embodiment, they are designed as collapsible folding elements, but do not necessarily have to be attached. Furthermore, the closing elements can have a damping effect, which is aimed at the mechanical movement of the cover flap 18th to dampen vibration-free so that the cover flap is not stimulated to a fluttering natural vibration by the airstream.

In 9A is the lid flap 18th by the pre-tensioning force of the spring element 17th closed. The speed of the vehicle is still too low, so that the compressive force generated by the airflow is insufficient, the pretensioning force of the spring element 17th to overcome.

In 9B is the lid flap 18th already opened at an angle, whereby after opening the cover flap 18th suddenly the inner surface of the lid flap 18th is exposed to the air pressure of the airstream, so that the cover flap 18th then opens quickly.

In 9C Fig. 3 is a perspective view of the embodiment of FIG 9A and 9B shown.

The 10A and 10B show a schematic representation of a cover flap according to the invention arranged on a vehicle 18th in a ninth embodiment of the invention. Since it is only a further development of the design 9A , 9B and 9C represents, a repeated description of the same mode of operation is dispensed with below.

In contrast to the previous embodiment according to the invention, the lateral closing elements 21 In this embodiment designed as curved flexible surface elements, which when the cover flap is in the closed position 18th , as in 10A shown, arching in a circle, and in the open position of the cover flap 18th as in 10B should be aligned flat. In a further embodiment according to the invention, the lateral closing elements can themselves serve as spring elements, so that an additional spring element can be used 17th can then be dispensed with.

The foregoing embodiments of the present invention are merely exemplary and should not be construed as limiting the present invention. The present teaching of the invention can easily be transferred to other applications. The description of the exemplary embodiments is provided for the purpose of illustration and not in order to restrict the scope of protection of the patent claims. Many alternatives, modifications and variations will be apparent to one of ordinary skill in the art without having to depart from the scope of protection of the present invention, which is defined in the following claims.

List of reference symbols

10

Ventilation opening

12th

Vehicle area, underbody area

13th

Swivel hinge

14th

Wall of the scoop

15th

Deflection element

16

Transmission element, cable pull

16n

meandering cable pull

17th

Spring element

18th

Lid flap

19th

additional inclined surface, ram pressure lip

20th

Actuator

21, 21a, 21b, 21c, 21d

lateral locking elements

22, 24

active material actuator, sheet metal strip

26A

front retaining element

26B

rear retaining element

Claims (31)

Motor vehicle with at least partially enclosing outer surfaces with at least one ventilation opening (10) provided therein for cooling and / or ventilation, which is arranged in a front engine compartment area frontally, laterally, above and / or below the body and / or in a rear area of the body and at least one ventilation opening (10) with at least one cover flap provided for opening and closing is provided for ventilating and / or venting at least one of the units belonging to the drive, air conditioning or braking devices by sucking in or blowing in outside air or air sucked out by the airstream (18) and closes the ventilation opening (10) in such a way that the outer surface of the lid flap (18) forms an aerodynamically favorable surface shape with the adjacent outer surfaces of the vehicle or its parts, the lid flap (18) is equipped with a drive, characterized in that de The drive of the cover flap (18) is designed with at least one material-active actuator (22, 24), the active actuator (22, 24) is a thermally acting element, such as a bimetallic element, expansion thermocouple, shape memory element, the active Actuating member (22, 24) is electrically heated with the aid of an additional heating element. Motor vehicle after Claim 1 , characterized in that the cover flap (18) is pivotably mounted on an edge of a surface belonging to the vehicle. Motor vehicle according to one of the preceding Claims 2 or 1 , characterized in that the actuating member (22, 24) is controlled by an electronic controller which evaluates a physical variable based on a sensor element signal and generates a control signal for operating the actuating member. Motor vehicle after Claim 1 , characterized in that the active actuating member (22, 24) is actuated directly thermophysically by the heat generated by the vehicle assemblies and / or by the air temperature of the airflow. Motor vehicle according to one of the preceding claims, characterized in that a wire element is used as an additional, electrically energized heating element. Motor vehicle according to one of the preceding claims, characterized in that a thin or thin-layer heating film is used as an additional, electrically energized heating element. Motor vehicle after Claim 1 , characterized in that the active actuating member (22, 24) is directly electrically energized to generate a heating power. Motor vehicle according to one of the preceding claims, characterized in that the active actuating member (22, 24) has at least two material-active elements arranged essentially next to one another, each of which can be electrically energized separately to generate a heating power. Motor vehicle after Claim 8 , characterized in that the material-active elements are designed as shape memory elements, each with a different preset switching temperature. Motor vehicle after Claim 2 , characterized in that the cover flap (18) pivotably mounted on an edge of a surface belonging to the vehicle is mounted in a swivel hinge (13) or a bending hinge in the longitudinal or transverse direction or in a direction in between with respect to the straight-ahead direction of travel of the vehicle is. Motor vehicle after Claim 1 , characterized in that the material-active actuating element (22, 24) is additionally used as a sensor element and supplies a measurement signal derived from a physical variable to a controller. Motor vehicle after Claim 1 , characterized in that the material-active actuating element made from a shape memory material is designed as a wire (16), several wires, a meandering wire (16n), a plate and / or a band. Motor vehicle after Claim 12 , characterized in that the shape memory Material-made actuator of the cover flap (18) has a predetermined effective temperature setting. Motor vehicle according to one of the preceding claims, characterized in that the cover flap (18) is designed to be actively closing or actively opening. Motor vehicle according to one of the preceding claims, characterized in that the ventilation opening (10) closed with the cover flap (18) is arranged in the direction against the headwind or in the direction facing away from the headwind. Motor vehicle after Claim 15 , characterized in that the pressure force of the airstream is used as an actuating force closing or opening the cover flap. Motor vehicle according to one of the preceding claims, characterized in that the cover flap (18) is pretensioned against the acting force with at least one resilient element. Motor vehicle according to one of the preceding claims, characterized in that the surface of the cover flap (18) is designed as a rigid flap surface or as a flexible flap surface. Motor vehicle according to one of the preceding claims, characterized in that the cover flap (18) is equipped with at least one element which engages in at least one step which corresponds to an opening step of the cover flap (18) and which can be unlocked. Motor vehicle after Claim 19 , characterized in that the locking element is designed as a micro-toothed hinge with a defined predetermined overcoming force as a mechanical ratchet with automatic locking. Motor vehicle according to one of the preceding claims, characterized in that the cover flap (18) is equipped with a displaceable mass which is arranged in a cavity provided in the cover flap (18). Motor vehicle according to one of the preceding claims, characterized in that the spring pretensioning the cover flap (18) is made from a material-active element such as a shape memory element and the spring constant of the pretensioning spring can be changed by changing the parameters of the material-active element. Motor vehicle after Claim 22 , characterized in that the spring biasing the cover flap (18) is arranged in a series and / or parallel connection of passive springs. Motor vehicle according to one of the preceding claims, characterized in that the bending hinge of the cover flap (18) is used as a sheet metal strip (24) with an element that is active in the material. Motor vehicle according to one of the preceding claims, characterized in that the actuating element used is at least one piezo element which is arranged in the swivel joint hinge (13) and is highly dynamically excited by a vibration signal. Motor vehicle according to one of the preceding claims, characterized in that a transmission element (16) is arranged between an actuating member (20, 22, 24) and the cover flap (18) or the vehicle surface (12). Motor vehicle after Claim 2 , characterized in that the cover flap (18) is biased towards the closed position by a spring element (17), its opening direction is oriented in the direction of travel and an additional inclined surface (19) is formed on the front section of the cover flap (18), which absorbs the dynamic pressure of the airstream. Motor vehicle after Claim 27 , characterized in that the spring element (17) is designed as a spiral, leg or spiral spring. Motor vehicle after Claim 27 , characterized in that the spring element (17) is formed by the surface of the cover flap (18), which for this purpose is formed from a resilient material. Motor vehicle after Claim 29 , characterized in that the spring element (17) formed by the surface of the cover flap (18) is provided with a “cracking frog effect” and has a stable and a metastable state. Motor vehicle after Claim 30 , characterized in that an elastic element covering at least one surface section is arranged on the surface of the lid flap (18) and is firmly connected to the surface of the lid flap (18).

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