JPH0367910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a device for reducing air resistance of a vehicle, and more particularly to a separation flow control device for reducing separation flow behind a vehicle.

(Prior Art) A conventional device for reducing the air resistance of a vehicle is disclosed in Japanese Patent Application Laid-Open No. 58-26683.
This device will be explained with reference to FIGS. 13 and 14.
In FIGS. 13 and 14, 1 is a vehicle body, 2 is a front part, 3 is a roof part, and 4 is a rear part. Inside the front part 2, there is an air intake port 16 for taking in air that has flowed into the front part 2 from the front grill part 5.
is provided, and this air intake port 16 is connected to the side pillar portion 6,
6' and the side edges 7, 7' of the roof part 3 to the vehicle body 1.
It communicates with an air guide path 17 that extends to the rear part of. A slit opening member 14 having a slit opening that communicates with the air guide path 17 and opens toward the outer surface of the rear outer wall 11 of the rear surface section 4 is attached to the rear end edge of the roof section 3. , left and right side outer walls 10,
The upper rear edge of 10′ communicates with the air guide path 17;
A slit opening forming member 12 having a slit opening that opens toward the outer surface of the rear outer wall 11 of the rear surface section 4 is attached, and the air guided by the air guide path 17 is directed to the upper edge of the rear surface section 4. and left and right edges 9, 9'
The air is ejected outwardly along the outer surface of the rear section 4, thereby adding an air flow to the boundary layer of air along the outer surface of the rear section of the vehicle body and actively forming the boundary layer. The objective is to maintain the air resistance and prevent the generation of vortices on the outer surface of the rear portion of the vehicle body, thereby suppressing the increase in air resistance that occurs as the speed of the vehicle increases.

(Problems to be Solved by the Invention) However, in the case of such a conventional air resistance reduction device, the air intake port 16 provided at the front part of the vehicle and the slit opening forming members 12 and 14 provided at the rear part are provided. The air resistance of the car body increases due to the ventilation resistance of the air passing through the air guide path 17 that communicates with the opening, and although it is possible to prevent the generation of vortices at the rear of the car body by the air flow blown out at the rear of the car body, There was a problem in that the boundary layer became thicker, causing backflow in a large area at the rear of the vehicle body, and large negative pressure acting on the rear surface of the vehicle body, resulting in little effect in reducing air resistance.

(Means for Solving the Problems) The present invention has been made in order to solve the problems in the conventional air resistance reduction devices for vehicles. It is a device that controls the flow generated at the rear of the vehicle body while the vehicle is running. An air intake port located at a portion closer to the rear end of the vehicle body than the outlet, and an air ventilation portion that communicates the air outlet and the air intake port, and a flap formed near the air intake port. suctioning the air in the flow through the air intake port;
This air is supplied from the air outlet through the air ventilation portion to a break-off point located near the air outlet.

(Function) According to this configuration, a break-up point at the rear of the car body, which is a position where the air flow from the car body surface starts to break off, is located in the vicinity of a part where the inclination angle of the car body surface with respect to the center part of the car body rapidly increases. By supplying air from the air outlet to the point, energy is supplied into the boundary layer near the point of separation, and air resistance is reduced by preventing the generation of vortices from the point of separation. be able to.

Furthermore, according to this configuration, the airflow that is generated at the rear of the vehicle body from the region where the above-mentioned inclination angle rapidly increases to the rear end of the vehicle body is separated from the surface of the vehicle body, becomes turbulent, and exerts negative pressure on the rear portion of the vehicle body. The air in the break-off flow is sucked in by the air intake port that communicates with the air outlet near the break-off point, where the negative pressure is greater than that in the break-off flow, through the air vent, so that the air flows smoothly toward the rear of the vehicle. By directing the airflow closer to the rear of the car body and diagonally downward, it is possible to reduce the area of separation flow behind the car body, thereby reducing the negative pressure exerted by the separation flow and further reducing air resistance. be able to.

Moreover, according to this configuration, the pressure difference between the air outlet and the air intake port, which are communicated through the air ventilation section, causes the air to be blown out from the air outlet and the air from the air intake port to be different from each other. Since suction is performed, the above effects can be achieved with a simple structure without using any special power.

(Example) An example in which the vehicular separation flow control device of the present invention is applied to an automobile will be described in detail below with reference to the drawings.

1 to 5 are diagrams showing one embodiment of the present invention. First, in FIG. 1, 20 indicates the entire automobile. An air intake port 22 is provided at the bottom of the rear door 21, and an air outlet 23 is provided at the top of the rear door 21, which is the area where the slope angle rapidly increases with respect to the roof surface in the center of the vehicle. The portion 24 allows communication. As shown in FIG. 2, the air intake 22 is connected to the outer panel 25 of the rear door 21.
A grill 26 is attached to the opening at the lower end to prevent dirt from entering, as shown in FIG. Further, a drain hole 28 is opened in the inner panel 27 at the lower end of the rear door 21. Air ventilation part 2
4 is formed in a space surrounded by an outer panel 25 and an inner panel 27 on both sides of the rear door 21, as shown in FIG. As shown in FIG. 5, the air outlet 23 is opened in an outer panel 25 at the upper end of the rear door 21, and a grill 29 is attached to the opening to prevent dust from entering.

Next, the operation of the vehicle separation flow control device of this embodiment will be explained. In FIG. 1, when air flows along the vehicle body as the vehicle travels, the flow velocity of the air increases near the upper end of the rear door 21 and the pressure becomes lower than near the lower end of the rear door 21. In addition, near the upper end of the rear door 21, the angle of inclination with respect to the roof surface increases rapidly, so the boundary layer begins to peel off from that position, and the boundary layer peels off from the surface of the car body from above the rear door 21 to behind the rear bumper. A region of separation flow, which is an air flow, is created. Therefore, air is blown out from the air outlet 23 due to the pressure difference near the upper and lower ends of the rear door.
This allows the air to pass through the air intake 2 through the air ventilation section 24.
Suction pressure is generated at the air intake port 22, and air from the peeling area at the rear of the vehicle is sucked in from the air intake port 22. The sucked air passes through the air ventilation section 24 to the air outlet 2.
It is blown out from 3. At this time, the air flow blown out from the air outlet 23 works to prevent the generation of vortices along the rear surface of the vehicle body from the break-off point where the above-mentioned break-off starts, and the air flow sucked in from the air intake port 22 Because it sucks in the air in the backflow area, it has the effect of reducing the backflow area. Furthermore, since the airflow can be created by natural convection without having to take the trouble to introduce the airflow from the front of the vehicle body, there is no increase in air resistance due to the introduction.

Figures 6 and 7 show a comparison of the air flow between a car equipped with a conventional air resistance reduction device with an air outlet at the upper end of the rear of the vehicle body and a car equipped with the separation flow control device of the present invention. It is a diagram. FIG. 6 shows a conventional example, and FIG. 7 shows an example of the present invention. In the figures, 30 indicates the flow of air. As is clear from Figures 6 and 7, in a car equipped with the device of the present invention, the air flow 30 changes downward from the rear of the vehicle, and from this point the boundary layer approaches the car body at the rear of the car body, causing a separation flow region. It can be seen that it is decreasing.

Next, an experimental example will be explained. Figures 8 A to E show the rear of the vehicle used in the experiment, A is the original with no opening at the rear, B is the one with an opening 31 at the rear end, and C is the roof end. D has an opening 31 at the roof end and air is blown out from the opening 31. E has an opening 31 at the roof end and an opening 32 at the rear end. The peeling flow control device of the present invention is provided, and these are communicated with each other.

When the air resistance coefficient CD of these vehicles was measured, the results shown in Figure 9 were obtained. A to E in FIG. 9 correspond to the vehicles in FIGS. 8 A to E, respectively. As shown in FIG. 9, the CD value of the case B, which had an opening 31 in the rear end, was almost different from that of the case A, which did not have any opening, and no significant CD value reduction effect was observed. The CD value was reduced by 0.014 in model C, in which an opening 31 was provided at the roof end corresponding to the upper end of the rear portion of the vehicle, than in model A, which did not have any opening. The one in D, in which air is blown out from the opening 31 provided at the roof end, has a CD value that is almost the same as that in C, and is better than A.
The CD value was reduced by 0.015. The CD value of E, which was equipped with the peel-off flow control device of the present invention, was reduced by 0.03 compared to A, which is almost double that of C and D.

Based on the above results, a vehicle equipped with the separation flow control device of the present invention is equipped with a conventional air resistance reduction device having an opening or an outlet at the rear of the vehicle body in order to reduce the negative pressure caused by the separation flow region. It was confirmed that the air resistance can be reduced by almost twice that of a conventional vehicle.

Next, another embodiment of the present invention will be described in detail with reference to FIGS. 10 and 11. In a car with a body shape that has a smooth connection between the roof and the rear door surface, no vortices are generated on the rear door surface, and the airflow flows as an adhesion flow to the rear end of the rear door, causing a break near the rear end of the rear door where the angle of inclination increases rapidly. Therefore, the area behind the vehicle body after that position may become a spillover area. This embodiment is adapted to an automobile having such a body shape. In FIGS. 10 and 11, an air intake port 34 is opened in a bumper 33 that is the rear end of the vehicle body, and an air intake port 34 is opened in a bumper 33 that is the rear end of the vehicle body, and an air intake port 34 is inserted into the rear end panel outer 35 and the rear end panel inner 37 through an opening 36 provided in a portion hidden behind the bumper 33 at the bottom of the rear end panel outer 35. An air intake port 34 is provided in the first air ventilation section 38 formed between the
communicate. Also rear end panel outer 35
An opening 39 is provided in the upper part of the rear door inner panel 40, and an opening 41 is provided in the rear door inner panel 40 so as to communicate with the opening 39. The second air ventilation section 43 formed between the rear door inner panel 40 and the rear door outer panel 42 connects to the first air ventilation section 3 through the openings 39 and 41.
Connects to 8. An air outlet 44 is opened in the rear door outer panel 42 located above the second air ventilation section 43 . A grill 45 is attached to this air outlet 44 to prevent dust from entering.

Next, the operation of the peel-off flow control device of this embodiment will be explained. As shown in FIG. 12, when the air flow 30 separates from the vehicle body after the rear end of the rear door, the air flow velocity increases near the rear end of the rear door and the pressure becomes lower than near the bumper at the bottom of the rear end.
Due to this pressure difference, air is blown out from the air outlet 44, and suction pressure is generated in the air intake 34 through the second air ventilation part 43 and the first air ventilation part 38, and the air from the air intake 34 in the peeling area at the rear of the vehicle body is is absorbed. The sucked air flows through the first air ventilation section 3.
8. Air outlet 4 through second air ventilation part 43
It is blown out from 4. At this time, the air flow blown out from the air outlet 44 works to prevent the generation of vortices near the rear surface of the vehicle body, and the air in the flow area is blown in from the air intake port 34, so that As shown in 31', the air flow changes and the separation flow area decreases, the negative pressure at the rear of the vehicle body decreases, and the CD value decreases.

In this way, in this example, the connection between the roof and the rear door is smooth due to the car's original shape.
This is effective in further reducing the CD value of vehicles with low CD values.

Although the above-described embodiment describes an example in which the present invention is applied to a vehicle having a rear door, it goes without saying that the present invention can also be applied to a vehicle without a rear door and a vehicle other than an automobile.

(Effects) As detailed above, according to the vehicular separation flow control device of the present invention, the air within the separation flow region is sucked in by the negative pressure near the separation point, thereby reducing the separation flow region. The negative pressure acting on the surface of the vehicle body is reduced by the flow, and the air resistance of the vehicle body is reduced, thereby significantly improving fuel efficiency.

In addition, for example, in the case of a hatchback vehicle that has a sloped surface at the rear of the vehicle body and a spillover region occurs along this slope, the negative pressure on this surface is reduced, so that the lift force can also be reduced. This also improves the running stability of the vehicle.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a vehicle to which an embodiment of the vehicle separation flow control device of the present invention is applied, FIG. 2 is an enlarged perspective view of the rear part of the vehicle in FIG. 1, and FIG. A
4 is a sectional view taken along line B-B in FIG. 2, FIG. 5 is a sectional view taken along line C-C in FIG. 2, and FIG. 6 is a sectional view taken along line C-C in FIG. 2. Figure 7 is a diagram showing the air flow around a vehicle equipped with the separation flow control device of the present invention, and Figures 8 A to E are vehicles used in air resistance comparison experiments. 9 is a characteristic diagram showing a comparison of air resistance coefficient values obtained through experiments. FIG. 10 is a rear perspective view of a vehicle to which another embodiment of the present invention is applied. The figure is a sectional view taken along the line D-D in Figure 10, Figure 12 is a diagram showing the air flow around the vehicle to which the embodiment of Figures 10 and 11 is applied, and Figure 13 is a diagram showing the flow of air around the vehicle to which the embodiment of Figures 10 and 11 is applied. The plan view of the installed vehicle, Figure 14, is the first
FIG. 4 is a side view of the vehicle of FIG. 3; 20...car, 21...rear door, 22...
Air intake, 23...Air outlet, 24...Air ventilation section, 25...Outer panel, 26...Grill, 27...Inner panel, 28...Water drain hole, 2
9...Grill, 30,30'...Air flow, 3
1, 32...opening, 33...bumper, 34...
Air intake, 35...Rear end panel outer,
36... Opening, 37... Rear end panel inner, 38... First air ventilation section, 39... Opening, 4
0...Rear door inner panel, 41...Opening, 4
2...Rear door outer panel, 43...Second air ventilation section, 44...Air outlet, 45...Grill.

Claims (1)

[Scope of Claims] 1. A device for controlling the flow generated at the rear of the vehicle body while the vehicle is running, which is located at the rear of the vehicle near a region where the angle of inclination of the vehicle surface relative to the center of the vehicle rapidly increases. an air outlet, an air intake located at a position closer to the rear end of the vehicle body than the air outlet, and an air ventilation section that communicates the air outlet and the air intake; The air in the break-off flow formed near the air intake port is sucked by the air intake port, and this air is supplied through the air ventilation portion from the air outlet to the break-off point located near the air outlet. A peeling flow control device for a vehicle, which is characterized by: 2. The air intake port opens in the lower half of the rear door, the air outlet opens in the upper half of the rear door, and the ventilation portion is located in a portion surrounded by the inner panel and outer panel of the rear door. A vehicle separation flow control device according to claim 1, which is installed in a vehicle.