Motor vehicle body with a plasma actuator

Abstract

Motor vehicle body with a plasma actuator, wherein the motor vehicle body (7) has a roof (8) and a movable tailgate (9), wherein the tailgate (9) is formed opposite a rear edge (11) of the roof (8), which is formed facing away from a front of the motor vehicle body (7), and wherein a first distance (13) and a second distance (14) are formed between the rear edge (11) and a flap edge (12) of the tailgate (9) opposite the rear edge (11) of the motor vehicle body (7), at least in the direction of a vertical axis (Z) of the motor vehicle body (7), and wherein the plasma actuator (1) has at least a first electrode (2) and a second electrode (3) which are connected to a power source (21), characterized in that the plasma actuator (1) is used to form a plasma (5) in a transition area (16) between the roof (8),at least the trailing edge (11), and the tailgate (9), at least the flap edge (12), comprising a movement gap (15), wherein the movement gap (15) between the trailing edge (11) and the flap edge (12) extends along a transverse body axis (Y) of the vehicle body (7), and wherein the first electrode (2) is arranged at or at least near the trailing edge (11) and the second electrode (3) is arranged at or at least near the flap edge (12).

Description

[0001] The invention relates to a motor vehicle body with a plasma actuator according to the preamble of claim 1.

[0002] Motor vehicle bodies with a tailgate are known. The tailgate is characterized by the fact that, starting from the front of the vehicle body, it is positioned adjacent to the rear end of the roof of the vehicle body, i.e., the trailing edge of the roof. Typically, the tailgate is pivotable about a hinge axis extending in the direction of a transverse axis of the body. However, it could also be designed in the form of a door, as is commonly seen, for example, in vans.

[0003] Furthermore, it is known to use plasma actuators to influence the air flowing around the vehicle body.

[0004] For example, a motor vehicle body with a plasma actuator can be taken from the documents JP 2012-210945 A1, CN 107651027 A, EP 2 458 188 B1 and JP 2010-179829 A, wherein the plasma actuator is attached to a rear edge of the roof to influence the airflow.

[0005] Patent EP 3 075 654 B1 describes a plasma actuator in the roof of a motor vehicle body, wherein the plasma actuator is mounted in the roof facing away from the airflow.

[0006] German patent applications EP 2 884 823 B1, JP 2010-158977 A and FR 2964357 A1 disclose a motor vehicle body with an air guide element in the rear area, wherein the air guide element is configured to include a plasma actuator. German patent application JP 2010-119946 A1 discloses a motor vehicle body with an air guide element in a front area of ​​the motor vehicle body, which is equipped with a plasma actuator.

[0007] For example, positioning the plasma actuator on the underbody of a motor vehicle body is described in US 7,887,119 B2. Further examples of plasma actuator placement can be found in US 7,624,941 B1, US 7,735,910 B2, US 8,641,127 B2, US 9,541,106 B1, and WO 2016 / 025699 A1.

[0008] The object of the present invention is to arrange a plasma actuator on the tailgate of a motor vehicle body in a space-saving manner and with efficient function.

[0009] The problem is solved according to the invention with a motor vehicle body comprising a plasma actuator with the features of claim 1. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the respective dependent claims.

[0010] A motor vehicle body according to the invention, comprising a plasma actuator, has a roof and a movable tailgate, the tailgate being formed opposite a rear edge of the roof which faces away from a front of the motor vehicle body. Between the rear edge and a flap edge of the tailgate opposite the rear edge, a first gap is formed at least in the direction of a vertical axis of the motor vehicle body and a second gap is formed in the direction of a longitudinal axis of the motor vehicle body. The plasma actuator has at least a first electrode and a second electrode which are connected to a power source.According to the invention, the plasma actuator for forming a plasma in a transition area between the roof, at least the trailing edge, and the tailgate, at least the flap edge, is arranged comprising a movement gap, wherein the movement gap between the trailing edge and the flap edge is designed to extend along a transverse body axis of the motor vehicle body, and wherein the first electrode is arranged at or at least near the trailing edge and the second electrode is arranged at or at least near the flap edge.

[0011] Since the vehicle body has a movable tailgate, regardless of whether it is designed as a tailgate that pivots around the transverse axis of the vehicle body or around the vertical axis, a gap is formed between the trailing edge and the edge of the tailgate. This gap is enlarged when a spoiler is attached to the trailing edge. Furthermore, the gap is usually stepped, meaning that the tailgate is offset downwards along the longitudinal axis of the body and towards the vertical axis, creating a step in the transition area between the roof and the tailgate.

[0012] In principle, regardless of whether the step is large, for example with the help of a spoiler, or whether no spoiler is fitted and the step is therefore very small, turbulence arises, particularly in the gap between the roof and the tailgate, which affects the airflow over the vehicle body. Therefore, to influence the airflow over the vehicle body, it is advantageous to position the plasma actuator specifically in the transition area between the roof and the tailgate to generate the plasma. Furthermore, it has been shown that the dead zone that forms behind the rear of the vehicle body during driving can be significantly reduced by generating the plasma in this transition area, thereby substantially lowering the drag coefficient. This, in turn, can be used to reduce the vehicle's fuel consumption.

[0013] To enable plasma generation directly in the transition zone, the first electrode is positioned at or at least near the trailing edge, and the second electrode is positioned at or at least near the edge of the tailgate. Since one electrode is thus located on one side of the transition zone and the other on the opposite side (viewed along the longitudinal axis of the vehicle body), the electronic field required to generate the plasma between the two electrodes can be precisely generated in the transition zone. The term "near" in this context means that, due to the specific material thickness of the roof and tailgate, as well as any folds that may be present, the exact edge cannot be precisely targeted.In other words, this means that the electrodes are positioned as close as possible to the relevant edge so that the electric field is generated effectively and quickly when the electrodes are energized.

[0014] Preferably, the first electrode is positioned on the roof, facing away from any roof surface, and / or the second electrode is positioned at the rear, facing away from any rear surface. In other words, the two electrodes are not visible from above, at least when the vehicle body is closed. This has the particular advantage of preventing contamination of the electrodes, especially by the air flowing along them and the particles contained therein.

[0015] In a further embodiment of the vehicle body according to the invention, the first electrode is uncovered facing the second electrode, or the second electrode is uncovered facing the first electrode. In this way, when both electrodes are energized, a plasma formation that occurs promptly, and in particular immediately, upon the start of the energization is achievable, since there is only a body layer between the two electrodes, which could potentially delay the formation of the electric field necessary to generate the plasma.

[0016] To prevent a short circuit, a dielectric, i.e. an insulating separating layer, is arranged between the first electrode and the second electrode.

[0017] The power source can be an alternating current source or a direct current source. Therefore, there is no requirement to use a specific type of power source.

[0018] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. Identical or functionally equivalent elements are assigned identical reference numerals. The figures show: Fig. 1 In a schematic diagram, a plasma actuator and its generated plasma, Fig. 2 in a schematic diagram a section of a motor vehicle body according to the invention with a plasma actuator, and Fig. 3 in a side view a section of the motor vehicle body according to the invention with dead water area with plasma actuator activated and with plasma actuator not activated.

[0019] The inducement of a change in the flow of an air mass flow using a so-called plasma actuator 1, as is basically described in accordance with Fig. The structure of the device is known. The change in flow is initiated by means of two electrodes, a first electrode 2 and a second electrode 3, depending on the current applied to them. A separating layer 4, in the form of a dielectric, is formed between the electrodes 2 and 3. As soon as the electrodes 2 and 3 are energized, an electric field is created between them, which contains plasma 5, and in particular ions.

[0020] In a specific region surrounding the plasma 5, the total pressure is lower than in the region outside this region, hereinafter referred to as the environment 6. In other words, a pressure difference is created using the plasma 5. Neutral air molecules from the environment 6 flow into the region of the plasma 5. It can be assumed that no pressure equalization occurs, since the ions of the plasma 5 transfer their inherent momentum to the air molecules, thereby accelerating the air molecules out of the plasma region. This leads to a change in the velocity of an airflow flowing along the plasma actuator 1.

[0021] A motor vehicle body 7 according to the invention, which according to Fig. 2 and Fig. The vehicle body 7, which is constructed as shown in Figure 3, has a roof 8 and a tailgate 9, forming a rear 23. In this embodiment, the tailgate 9 is designed as a flap that can pivot upwards, towards the roof 8, about a pivot axis 10. The pivot axis 10 extends in the direction of a transverse body axis Y, which is orthogonal to a vertical body axis Z and a longitudinal body axis X. Alternatively, the tailgate 9 could also be designed as a one- or multi-part door that can pivot about an axis extending in the direction of the vertical body axis Z.

[0022] The tailgate 9 is positioned opposite a rear edge 11 of the roof 8, which faces away from a front of the vehicle body 7 (not shown). Between the rear edge 11 and a flap edge 12 opposite the rear edge 11, extending in the direction of the body's transverse axis Y, there is a gap, a first gap 13 and a second gap 14, respectively, extending along the body's transverse axis Y, both in the direction of the body's vertical axis Z and in the direction of the body's longitudinal axis X. In other words, there is a stepped movement gap 15 extending along the body's transverse axis Y, with gaps 13 and 14, between the rear edge 11 and the flap edge 12.

[0023] To bring about the change in flow, the plasma actuator 1 is arranged in a space-optimized manner to form the plasma 5 in a transition area 16 between the roof 8, at least the trailing edge 11, and the tailgate 9, at least the flap edge 12, encompassing the movement gap 15.

[0024] The first electrode 2 is associated with the roof 8, wherein the first electrode 2 is arranged facing away from a roof surface 17 of the roof 8. It is positioned in the direction of the longitudinal axis X of the body at the rear edge 11, preferably flush with this.

[0025] The second electrode 3 is arranged on the tailgate 9, facing away from a rear surface 18 of the tailgate 9 and extending from the edge of the tailgate 12 in the direction of the longitudinal axis X of the vehicle body towards a bumper 19 of the vehicle body 7. It is preferably positioned flush with the edge of the tailgate 12.

[0026] The first electrode 2 is positioned opposite the second electrode 3, with its end 20 opposite the second electrode 3 being uncovered.

[0027] The two electrodes 2, 3 are connected to a current source 21 for energization, which can be configured as a direct current source or an alternating current source. This can be a single current source 21 or two independent current sources 21. These must preferably supply current to the electrodes 2, 3 simultaneously so that the plasma 5 can form.

[0028] To prevent a short circuit when the power source is activated, the dielectric 4 is arranged between the first electrode 2 and the second electrode 3. In other words, an insulator in the form of the dielectric is formed between the two electrodes 2 and 3. The dielectric 4 is preferably positioned flush with the flap edge 12 and extends from this edge along a flap surface 22 in the direction of the vehicle's vertical axis Z. The width of the dielectric 4 extending in the direction of the vehicle's vertical axis Z depends on the defined distances 13 and 14.

[0029] If the two electrodes 2, 3 are energized, the plasma 5 is formed and an air mass flowing over the vehicle body 7 is deflected by the plasma 5 as described above. Fig. Figure 2 shows an example of an air mass flow without activated plasma actuator 1, represented by a solid line arrow, and an example of an air mass flow with activated plasma actuator 1, represented by a dashed line arrow. This allows, for example, the advantageous selection of a smaller outflow angle Gamma for a roof spoiler 25.

[0030] Depending on the deflection of the air mass flow, a change occurs in a so-called dead water area 24 at the rear 23 of the vehicle body 7, whereby the dead water area 24 is reduced when the plasma actuator 1 is activated, as exemplified in Fig. Figure 3 is shown. This leads to a reduced pressure resistance, resulting in a lower overall resistance coefficient for the vehicle body 7 during operation, which makes it possible to reduce energy consumption during the operation of the vehicle body 7.

[0031] In comparison to the dead water area 24 with activated plasma actuator 1, a dead water area 24 with inactive plasma actuator 1 is illustrated, where the hatched area is the dead water area 24 with activated plasma actuator 1 and the dotted area, in addition to the hatched area, is the dead water area 24 with inactive or non-existent plasma actuator 1. Reference symbol list 1 Plasma actuator 2 First electrode 3 Second electrode 4 Separation layer, dielectric 5 Plasma 6 Environment 7 Motor vehicle body 8 Roof 9 Tailgate 10 Rotation axis 11 trailing edge 12 flap edge 13 First gap 14 Second gap 15 Movement gap 16 Transition area 17 Roof surface 18 Rear area 19 bumpers 20 End of the second electrode 21 Power source 22 flap area 23 Rear 24 Torwasser area 25 roof spoilers X Body longitudinal axis Y body transverse axis Z Body vertical axis γ Outflow angle

Claims

[1] Motor vehicle body with a plasma actuator, wherein the motor vehicle body (7) has a roof (8) and a movable tailgate (9), wherein the tailgate (9) is formed opposite a rear edge (11) of the roof (8) which is formed facing away from a front of the motor vehicle body (7), and wherein a first distance (13) and a second distance (14) are formed between the rear edge (11) and a flap edge (12) of the tailgate (9) opposite the rear edge (11) of the motor vehicle body (7) at least in the direction of a vertical axis (Z) of the motor vehicle body (7) and wherein the plasma actuator (1) has at least a first electrode (2) and a second electrode (3) which are connected to a power source (21), characterized by, that the plasma actuator (1) for forming a plasma (5) in a transition area (16) between the roof (8), at least the trailing edge (11), and the tailgate (9), at least the flap edge (12), comprising a movement gap (15), wherein the movement gap (15) between the trailing edge (11) and the flap edge (12) extends along a transverse body axis (Y) of the motor vehicle body (7), and wherein the first electrode (2) is arranged at or at least near the trailing edge (11) and the second electrode (3) is arranged at or at least near the flap edge (12). [2] Motor vehicle body according to claim 1, characterized by , that the first electrode (2) is arranged on the roof (8) facing away from a roof surface (17). [3] Motor vehicle body according to claim 1 or 2, characterized by, that the first electrode (2) is exposed facing the second electrode (3) or the second electrode (3) is exposed facing the first electrode (2). [4] Motor vehicle body according to any of the preceding claims, characterized by , that a dielectric (4) is arranged between the first electrode (2) and the second electrode (3). [5] Motor vehicle body according to any of the preceding claims, characterized by , that the power source (21) is an alternating current source or a direct current source.

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