Motor vehicle underbody paneling with air intake

Abstract

The invention relates to a motor vehicle underbody panel with an air intake (2) which is delimited towards the vehicle or the road surface by an upper and a lower flat element (2; 3), respectively, which extend in an arc to the rear and upwards towards a vehicle compartment (1) in which components of the vehicle requiring cooling are located. According to the invention, the upper flat element (3) extends from a front end located in the longitudinal direction of the vehicle in front of, beside, or behind an internal combustion engine of the motor vehicle and below a front radiator, initially approximately horizontally and at a distance below an oil pan of the internal combustion engine, and then in a continuously steepening arc to its rear end located behind the oil pan, to which a flat air baffle plate (5) is attached. This plate extends a distance (h) substantially vertically upwards and then terminates substantially freely in the engine compartment.Furthermore, the lower planar element (4) extends from a front end located in the longitudinal direction of the vehicle behind the rear end of the upper planar element (3) in a steeper arc to the rear and upwards than the upper planar element (3) to a rear end located even further back and significantly higher than the rear end of the upper planar element.

Description

[0001] The invention relates to a motor vehicle underbody paneling with an air inlet which is delimited towards the vehicle or the roadway by an upper and a lower flat element, respectively, which each extend in an arc-shaped manner rearward and upward in the direction of a vehicle compartment in which components of the vehicle to be cooled are located, according to the preamble of patent claim 1.

[0002] Such an underbody panel is known from DE 10 2012 205 582 A1. This underbody panel is designed as a diffuser in the rear area of ​​a motor vehicle, with the lower flat element formed by a panel of the rear bumper and not ending freely, but rather curving forward in an arc.

[0003] In motor vehicles with an internal combustion engine, for example, there may be components in the engine compartment in front of, to the sides, and especially behind the internal combustion engine that require the coolest possible airflow for optimal cooling. This air should be cooler than the generally warmer air that has passed through the front radiator and the associated fan and then generally flows through the rest of the engine compartment. However, the latter air may be cool enough for other components, especially those closer to the engine. In general, however, the air intake can also be used for any other type of air supply for devices or components, not just for cooling.

[0004] To cool components behind the combustion engine, which heat up during operation and must not overheat, with fresh air, a so-called NACA air intake can be provided. This is a streamlined air intake in the underbody paneling that extends below the engine's oil pan and opens into the compartment behind the engine. However, a NACA air intake requires certain minimum dimensions to function efficiently, in particular a certain length and height relative to the vehicle's longitudinal direction. At the same time, its lowest section must be at a legally prescribed minimum distance from the road surface. Therefore, a NACA air intake limits the available packing space above it in the engine compartment.

[0005] The NACA air intake in the aforementioned DE 10 2012 205 582 A1 has a relatively low installation height, but this is sufficient here because only one component directly above it needs to be cooled, namely a rear muffler, which is also housed in a housing through which the supplied fresh air flows. To ensure that components located higher up in the engine compartment can also be well supplied with fresh air, the NACA air intake would have to extend as far as that point, as otherwise the cool air flow would be prematurely split, particularly by the warmer air circulating in the engine compartment, which has flowed through the front radiator and the associated fan. Due to its design, the NACA air intake has a linearly inclined ramp with a correspondingly relatively high installation height.

[0006] The invention is based on the object of designing a motor vehicle underbody panel with an air intake in such a way that it takes up relatively little space in the engine compartment and optimally supplies cooling fresh air, particularly vertically, but also to components located in front of, to the side, or behind the combustion engine. This function should be as neutral as possible with regard to harmful resistances, such as vehicle aerodynamic drag.

[0007] This problem is solved by an underbody panel having the features of patent claim 1.

[0008] Advantageous further developments of the invention are specified in the dependent patent claims.

[0009] The invention provides an improved NACA air intake, a so-called “Flat Efficient Submerged Airintake Device” (FESAD) air intake, which is less inclined than a NACA duct and has a lower overall height.

[0010] According to the invention, the upper flat element runs from a front end located in the vehicle's longitudinal direction, in particular in front of an internal combustion engine of the motor vehicle and below a front radiator, initially approximately horizontally and at a distance of, for example, a few centimeters beneath an oil pan of the internal combustion engine and then in a continuously steepening arc to its rear end located behind the oil pan. Adjoining this is a flat air baffle plate that runs essentially vertically upwards for a short distance and then ends essentially freely in the engine compartment. This air baffle plate, which bends vertically from the upper flat element, deflects the warmer air, which the front radiator's fan allows to pass between the oil pan and the upper flat element, from the cooler air flow through the FESAD air inlet, so that the latter is not disrupted.In addition, the lower flat element runs from a front end located behind the rear end of the upper flat element in the vehicle's longitudinal direction in a much steeper arc than the upper flat element backwards and upwards to a rear end located even further back and significantly higher, e.g., by approximately 10 to 25 centimeters, than the rear end of the upper flat element.

[0011] It has been shown that the flow separation effect of a relatively short, flat air baffle plate that bends off from the upper flat element and then ends freely in the engine compartment is practically as good as if the upper flat element were continued in a curve, although it would have to be considerably longer and would therefore take up more space in the engine compartment in order to ensure reliable air flow to the components mentioned, which are particularly easy to cool.

[0012] Therefore, the underbody paneling according to the invention can be designed to be relatively flat as a whole or at least partially, particularly below the components in the installation space, such as an internal combustion engine in the engine compartment, which is why the engine and the entire drive train can be arranged lower in the vehicle while maintaining the same ground clearance, as is desirable for some motor vehicles.

[0013] In preferred embodiments, the front end of the lower planar element is located by a given height difference of preferably a few centimeters below the lowest point of the upper planar element, which is usually located at its front end.

[0014] The flat air baffle plate preferably extends a few centimeters essentially vertically upwards to its free end, whereby a few centimeters here means a range of approximately 2 to 10 centimeters.

[0015] In preferred embodiments, at least the upper planar element becomes wider from front to rear in relation to the vehicle transverse direction.

[0016] The air inlet may include at least one additional air deflector extending parallel to the intended air flow and dividing the air flow into parallel sub-flows on part of its path through the air inlet.

[0017] The following is a description of exemplary embodiments based on the drawings. They show: Fig. 1 is a schematic sectional view of a FESAD air intake for cooling components in the engine compartment of a motor vehicle; Fig. 2 a view of the FESAD air inlet in Fig. 1 from below; and Fig. 3 a schematic partial sectional view of a further development of the FESAD air inlet of Fig. 1 and Fig. 2.

[0018] Fig. Figure 1 shows, by way of example, a longitudinal section through a motor vehicle, a schematic section of an engine compartment located at the front of the vehicle. This section includes an elliptically bordered area 1 containing one or more components of the vehicle or its drive system that become hot during operation and require special cooling. Area 1 is located behind an internal combustion engine (not shown) as viewed in the longitudinal direction of the vehicle.

[0019] A FESAD air inlet 2, a duct formed in a not-shown underbody panel of the vehicle, serves to cool the components in area 1. It is defined by an upper flat element 3, which begins below a not-shown front radiator, on the engine compartment and engine side, and by a lower flat element 4, which begins at the roadway, as well as by side walls not shown here. The flat elements 3 and 4 each extend in an arc shape backwards and upwards toward area 1.

[0020] While driving, relatively cool fresh air flows from the underbody into area 1, as indicated by solid arrows. In addition, above the upper flat element 3, there is a relatively warm air flow, indicated by a dashed arrow, from a fan of a front radiator passing under an oil pan of the internal combustion engine. The internal combustion engine is located to the left of the dashed arrow and above the upper flat element 3 in the figure.

[0021] With a conventional air inlet design, both the upper flat element and the lower flat element would extend in continuously steepening curves. However, with such a design, a portion of the warmer air flowing above the upper flat element would be directed into the area to be cooled 1, obstructing the flow of fresh air through the air inlet 2.

[0022] At the Fig. 1, the rear end of the upper flat element 3 is adjoined by a flat air baffle plate 5, which extends a distance h essentially vertically upwards and then ends essentially freely in the engine compartment, wherein h is essentially only limited by components located in the installation space, so that the air inlet 2 has an air outlet surface directed towards the cooling component, which in Fig. 3 is indicated by dashed lines. The distance h must be designed to the maximum extent possible based on the conditions prevailing in the installation space, and the angle at which the air outlet surface of the FESAD air intake is inclined relative to the vehicle's longitudinal direction results from the installation space conditions and, in this example, is approximately 20 degrees, with a variation of ±10 degrees.

[0023] The short, vertically bent air baffle plate 5 has the effect of deflecting the warmer air flow upwards or sideways, so that the cooler and warmer air flows remain largely separated even behind the air baffle plate 5 and the area 1 is exclusively exposed to the cooler air, as desired.

[0024] The described and shown design makes it possible to make the vertical extension of the FESAD air intake 2 smaller than that of a conventionally designed NACA air intake, so that space is gained in the engine compartment, especially in the area above the upper flat element 3.

[0025] As from Fig. 2, the air inlet 2 is laterally delimited by side walls 6, which extend more or less vertically between the upper and lower flat elements 3, 4 and connect them to each other.

[0026] As in Fig. 3, shown with dashed lines, the air intake 2, and in particular the upper flat element 3, together with the side walls, can widen toward the front of the vehicle to capture more air and accelerate it along its length. Faster-flowing air allows the sensitivity to flow separation caused by changing pressure conditions in the engine compartment to be reduced at the upper flat element 3 or to be curved more sharply.

[0027] As from Fig. 1, an effective opening cross-section of the air inlet 2 in the vertical direction is determined not only by the front width of the air inlet 2 but also by a dimension Δh, by which a front and lower end 7 of the lower flat element 4 or an optionally attached rubber lip is lower than the front and lower end of the upper flat element 3. The dimension Δh can, for example, vary in a range from a few millimeters to 10 centimeters, with the minimum dimension depending on the desired air throughput.

[0028] A diagonal opening cross-section of the air inlet 2 is determined by the distance A between the front and lower end 7 of the lower flat element 4 and the connection point between the upper flat element 3 and the air baffle plate 5. The air inlet 2 has a total length L.

[0029] As shown in the partial sectional view of Fig.As shown in Figure 3, one or more arcuate air baffles 8 can additionally be arranged in the air inlet 2, the curvature of which is adapted to the curvature of the upper and lower flat elements 3, 4, so that they run parallel to the intended air flow and initially split the air flow through the air inlet 2 into parallel partial flows and then recombine them. Such an air baffle 8 initiates the formation of a new stable boundary layer in the air flow.

Claims

[1] Motor vehicle underbody panelling with an air inlet (2) which is delimited towards the vehicle by an upper flat element (3) and towards the roadway by a lower flat element (4), each of which extends in an arc-shaped manner backwards and upwards in the direction of a vehicle compartment (1) in which components of the vehicle to be cooled are located, characterized bythat the upper flat element (3) runs from a front end located in the vehicle longitudinal direction in front of an internal combustion engine of the motor vehicle and below a front radiator, initially horizontally and at a distance below an oil pan of the internal combustion engine and then in a continuously steepening arc to its rear end located behind the oil pan, to which a flat air baffle plate (5) is connected, which runs vertically upwards for a distance (h) and then ends freely in the engine compartment, and that the lower flat element (4) runs from a front end located behind the rear end of the upper flat element (3) in the vehicle longitudinal direction in a steeper arc than the upper flat element (3) backwards and upwards to a rear end located even further back and higher than the rear end of the upper flat element. [2] Underbody paneling according to claim 1, characterized bythat a front end (7) of the lower planar element (4) lies by a given height difference (Δh) below the lowest point of the upper planar element (3) or below its front end. [3] Underbody paneling according to claim 2, characterized by that the height difference (Δh) is up to 10 centimeters. [4] Underbody paneling according to one of the preceding claims, characterized by that the flat air baffle plate (5) extends 2 to 10 centimeters vertically upwards. [5] Underbody paneling according to one of the preceding claims, characterized by that at least the upper flat element (3) becomes wider from front to back. [6] Underbody paneling according to one of the preceding claims, characterized bythat the air inlet (2) contains at least one additional air baffle (8) which runs parallel to the intended air flow and divides the air flow into parallel partial flows on part of its path through the air inlet (2).

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