JP2024067795A - Vehicle underbody structure - Google Patents

Abstract

[Problem] To provide a vehicle underbody structure for a passenger vehicle capable of generating strong downforce. [Solution] The vehicle underbody structure of the present invention comprises an undercover that covers at least the underside of the rear part of the vehicle, a plurality of vertical wall sections suspended from the undercover and extending in the front-rear direction of the vehicle, and a shelf section that is provided parallel to the undercover and bridges the vertical intermediate section between the vertical wall sections. The vertical wall sections are provided between the wheel houses of the rear wheels, and within the region in which the vertical wall sections are provided, the shelf sections are provided in the side regions on both sides in the vehicle width direction, and not in the central region in the vehicle width direction. As a result, the running wind that is drawn in under the vehicle from the sides of the vehicle and the rectified running wind that enters from the front of the vehicle are separated, making it possible to generate strong downforce. [Selected Figure] Figure 2

Description

The present invention relates to a vehicle underbody structure, and more specifically, to a vehicle underbody structure that generates downforce.

When various parts are exposed underneath the vehicle, the cavities between the exposed parts disrupt the airflow and create resistance when driving at high speeds, so in recent years undercovers are installed on the underside of the vehicle.

The undercover allows the wind that enters under the vehicle from the front to flow smoothly, and when the flow speed of the wind under the vehicle increases, according to Bernoulli's theorem, the pressure under the vehicle decreases, generating downforce that pulls the vehicle downward.

Non-Patent Document 1 describes a vehicle underbody structure that has an opening on the underside of the undercover, located forward of the rear axle and in the center of the vehicle width, and generates downforce by rectifying the airflow drawn in from this opening.

Banned "revolutionary" devices 4: The "magic" double diffuser that changed the balance of power 2020/05/26 Written by: Matt Somerfield URL https://jp.motorsport.com/f1/news/banned-why-double-diffusers-were-outlawed/4793903/

However, the vehicle underbody structure described in Non-Patent Document 1 relates to the vehicle underbody structure of a racing car, which has an extremely low minimum ground clearance. Since passenger cars with high minimum ground clearance and racing cars have different structures near the rear wheels, such as the presence or absence of wheel houses, and the air flow under the vehicle due to the rear wheels is different, it is difficult to generate downforce in a similar way.

The present invention was made in consideration of the problems with the conventional technology, and its purpose is to provide a vehicle underbody structure that can generate strong downforce in a passenger car that has a higher ground clearance and wheelhouse compared to a racing car.

As a result of extensive research into achieving the above-mentioned objective, the inventors have discovered that in passenger vehicles with high ground clearance, the wind blows against the rear wheels, drawing air under the vehicle from the sides, disrupting the flow of the wind underneath the vehicle and slowing down the flow rate of the wind underneath the vehicle.

Then, they discovered that the above objective could be achieved by drawing air under the vehicle from the sides and separating the turbulent wind from the straightened wind coming from the front of the vehicle, and thus completed the present invention.

That is, the vehicle underbody structure of the present invention includes an undercover that covers at least the rear lower surface of the vehicle,
a plurality of vertical wall portions suspended from the undercover and extending in a front-rear direction of the vehicle;
A shelf portion is provided parallel to the undercover and bridges the vertical intermediate portions between the vertical wall portions.
The vertical wall portion is provided between the wheel houses of the rear wheels, and within the area in which the vertical wall portion is provided, the shelf portion is provided in the side areas on both sides in the vehicle width direction, and no shelf portion is provided in the central area in the vehicle width direction.

The present invention provides a vehicle underbody structure that separates the traveling wind that is drawn in from the sides of the vehicle under the vehicle from the rectified traveling wind that enters from the front of the vehicle, thereby increasing the speed of the traveling wind from the front of the vehicle that flows through the central area under the vehicle, thereby generating strong downforce.

1 is a diagram showing an example of a vehicle underbody structure according to the present invention as viewed obliquely from below and behind the vehicle. 1 is a diagram showing an example of a vehicle underbody structure according to the present invention as viewed obliquely from below and in front of the vehicle. 4 is a graph showing the results of measuring the pressure under the vehicle.

The vehicle underbody structure of the present invention will now be described in detail.
As shown in FIG. 1 , the vehicle underbody structure of the present invention comprises an undercover that covers the underside of the vehicle, a plurality of vertical wall portions suspended from the undercover and extending in the fore-and-aft direction of the vehicle, and a shelf portion that is arranged parallel to the undercover and bridges the vertical intermediate portions between the vertical walls.

The undercover covers the various parts located under the vehicle, prevents air from entering the gaps between the parts, and allows the wind flowing under the vehicle to flow smoothly to the rear of the vehicle.

The undercover needs to cover at least the front end of the rear wheel housing to the rear end of the vehicle, but it is preferable for it to be continuous from the front of the vehicle.

This streamlines the wind from the front of the vehicle flowing underneath the vehicle, allowing it to flow smoothly underneath the vehicle and generate downforce.

Note that "continuous from the front of the vehicle" means that the underside of the vehicle is continuously covered, and does not mean that the undercover is not divided.

When the undercover allows the wind to flow smoothly underneath the vehicle, creating negative pressure underneath, the difference in pressure between underneath the vehicle and the sides of the vehicle makes it easier for the wind to be drawn in from the sides of the vehicle.

As shown in FIG. 1, the vertical wall portion extends in the fore-and-aft direction of the vehicle and is provided near the wheel houses between the wheel houses of the rear wheels to prevent the wind that hits the rear wheels and is drawn in from the side of the vehicle under the vehicle from entering the central area in the vehicle width direction.

By providing two or more of the vertical wall sections side by side near the wheel houses of the left and right rear wheels, air flow paths extending in the fore-and-aft direction of the vehicle are formed near the wheel houses.

As a result, as shown in FIG. 2, it is possible to separate the flow of the traveling wind flowing through the central region in the vehicle width direction from the front of the vehicle from the flow of the traveling wind drawn in from the sides of the vehicle, and it is possible to prevent the traveling wind drawn in from the sides of the vehicle from disturbing the traveling wind, which has a high flow rate from the front of the vehicle, and causing its flow rate to decrease.

As a result, the flow speed of the wind from the front of the vehicle flowing through the central area in the vehicle width direction, as shown by the thick arrow in Figure 2, increases, the pressure under the vehicle decreases, and a strong downforce can be obtained.

Furthermore, when the air drawn in from the vehicle side passes over the vertical wall section closer to the wheelhouse, a pressure difference occurs between the outside and inside in the vehicle width direction near the vertical wall section, which creates a swirling flow in the air flow path as shown in Figure 2, and downforce can be generated even in the air flow path between the vertical walls.

The air flow passage may be formed near each of the left and right wheel houses, but multiple air flow passages may be formed on each side.

The shelf is arranged parallel to the undercover and vertically separates the wind flowing through the airflow path under the vehicle formed by the vertical wall.

The wind that flows under the vehicle is slower on the ground side and faster on the vehicle body side. The wind that flows through the air flow path is drawn in from the side of the vehicle, and since it is swirling and not yet completely straightened, it is affected by the slower wind on the ground side.

The shelf section separates the traveling wind flowing through the air flow path in the vertical direction, and an air flow path is formed that is surrounded by the two vertical wall sections, the undercover, and the shelf section. This means that the traveling wind flowing through this surrounded air flow path is not only unaffected by the slower traveling wind on the ground side, but also by the traveling wind drawn in from the side of the vehicle.

As a result, the wind flowing through the enclosed air flow path is prevented from becoming turbulent, and the wind speed increases, generating downforce.

As long as a portion of this shelf portion is provided in the vertically intermediate portion between the vertical wall portions, it is not necessary for the entire shelf portion to be provided in the vertically intermediate portion between the vertical wall portions. For example, the front end of the shelf portion may start from the lower end of the vertical wall portion in accordance with the shape of the vertical wall portion.

It is sufficient that the shelf portion is provided in the air flow path near the wheel house, and is not provided in the central region in the vehicle width direction. That is, in the region where the vertical wall portion is provided, the shelf portion is provided in the side regions on both sides in the vehicle width direction, and the shelf portion is not provided in the central region in the vehicle width direction.
Since the central region in the vehicle width direction is subject to high-speed traveling wind from the front of the vehicle, by not providing a shelf portion in the central region in the vehicle width direction, in combination with the vertical wall portion, as shown in Figure 2, the high-speed traveling wind can blow directly through the central region in the vehicle width direction, thereby obtaining a strong downforce.

In this way, the vehicle undercarriage structure of the present invention separates the wind flowing under the vehicle into the vehicle width direction and the vehicle height direction.

As a result, the wind speed flowing from the front of the vehicle through the central region in the vehicle width direction is prevented from being slowed down by the wind speed blown in from the sides of the vehicle, and the wind speed flowing through the air flow passage is prevented from being affected by the slower wind speed near the ground, generating an extremely strong downforce.

Furthermore, in the vehicle underbody structure of the present invention, it is preferable that the undercover rises from a position rearward of the front end of the rear wheel house and forward of the rear wheel axle toward the rear end of the vehicle, and that the shelf portion rises along the undercover.

The undercover rises from near the rear wheels toward the rear end of the vehicle, allowing the wind flowing through the central area of the vehicle's width to be diffused toward the rear of the vehicle, generating negative pressure near the rear wheels and increasing the downforce generated near the rear wheels.

In addition, because the shelf rises up parallel to the undercover, the cross-sectional area of the air flow path enclosed by the two vertical walls, the undercover, and the shelf is constant from the front to the rear of the vehicle, and there is no change in pressure within the enclosed air flow path, allowing the wind to flow smoothly through the air flow path and creating downforce.

In the vehicle undercarriage structure of the present invention, it is preferable that the front end of the vertical wall portion is located rearward of the front end of the wheel house and forward of the rear wheel axle, and the front end of the shelf portion is located rearward of the rear wheel axle and forward of the rear end of the wheel house.

The vertical wall portion starts behind the front end of the wheelhouse and in front of the rear wheel axle, where the undercover begins to rise, so that the vertical wall portion does not come into contact with the ground, and traveling wind that comes into contact with the rear wheel and is drawn under the vehicle from the side can be prevented from heading toward the central area in the vehicle width direction.

In addition, if the shelf portion starts behind the rear wheel axle and forward of the rear end of the wheel house, the shelf portion does not prevent the traveling wind drawn in from the side of the vehicle from entering the air flow path near the rear wheels, and the traveling wind flowing through the air flow path near the rear wheels can be separated vertically.

In the vehicle underbody structure of the present invention, it is preferable that the vertical wall portion and the shelf portion are provided symmetrically on the left and right. This makes it possible to generate downforce that is well balanced on the left and right.

Figure 3 shows the results of measuring the pressure under the vehicle with the vehicle undercarriage structure (embodiment) having the vertical wall and shelf portion structure shown in Figure 1, and the pressure under the vehicle with only the undercover (comparison example), from the front to the rear of the vehicle.

The results in Figure 3 show that the vehicle underbody structure of the present invention has lower vehicle underbody structure pressure near the rear wheels than the comparative example, generating stronger downforce.

REFERENCE SIGNS LIST 1 undercover 11 rise start point 2 vertical wall portion 21 vertical wall portion front end 3 shelf portion 31 shelf portion front end 4 air flow path 5 rear wheel 6 wheel house

Claims (4)

An undercover that covers at least the rear underside of the vehicle;
a plurality of vertical wall portions suspended from the undercover and extending in a front-rear direction of the vehicle;
a shelf portion provided parallel to the undercover and bridging a vertical intermediate portion between the vertical wall portions,
The vertical wall portion is provided between wheel houses of the rear wheels,
A vehicle underbody structure, characterized in that, in the region in which the vertical wall portion is provided, the shelf portion is provided in side regions on both sides in the vehicle width direction, and the shelf portion is not provided in a central region in the vehicle width direction. The undercover rises from behind the front end of the rear wheel house and in front of the rear wheel axle toward the rear end of the vehicle,
2. The vehicle underbody structure according to claim 1, wherein the shelf portion is raised along the undercover. a front end of the vertical wall portion is located rearward of a front end of a wheel house and forward of an axle of a rear wheel,
3. The vehicle underbody structure according to claim 2, wherein a front end of the shelf portion is located rearward of an axle of a rear wheel and forward of a rear end of a wheel house. The vehicle undercarriage structure according to claim 2, characterized in that the vertical wall portion and the shelf portion are provided symmetrically on the left and right.

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