JP2009154827A - Air resistance reduction device of automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air resistance reduction device of a vehicle, which can improve aerodynamic performance by airflow control and reduce vehicle size without changing a cabin shape. <P>SOLUTION: A round ending portion 25a at the front end of a box-type vehicle 10 is provided with a guide member 40 across substantially the entire width of the box-type vehicle 10, which guides an air flow the front of the box-type vehicle 10 upward to generate air eddies. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an automobile air resistance reduction device that is installed on a roof of an automobile and reduces the air resistance during traveling, and more particularly to a technique effective for a box-shaped vehicle.

  From the viewpoint of improving the fuel efficiency of automobiles, it is desirable to reduce the air resistance during automobile driving. A box-shaped vehicle has a vertical surface with a substantially rectangular front surface, and air resistance generated during traveling is particularly large. Especially in large buses, the airflow that flows around the back of the vehicle differs depending on the airflow that flows along the top and side of the vehicle. If the low pressure area on the back of the vehicle is large, the pressure acting on the vehicle front is relatively large. Thus, when the low pressure region is small, the pressure acting on the front surface of the vehicle becomes relatively small. Therefore, there is a need for a method or structure for reducing the Cp value (pressure resistance coefficient) by reducing the low pressure region of the back surface during vehicle travel.

  In order to control the state of the airflow flowing along the upper and side surfaces of the vehicle body, it is necessary to change the overall shape such as the roof shape of the cab (cabin shape) or the wedge shape of the corner portion. However, since it is difficult to change the shape after the design or the like of the vehicle is determined, measures such as attaching an air resistance reducing device (rear spoiler) to the rear end of the roof are taken.

In addition, as a technology for controlling the air flow around the vehicle, there is a case where the air resistance reduction device for the vehicle that controls the separation phenomenon of the air flow generated in the vicinity of the rear window of the vehicle body or the opening of the sunroof equipped vehicle is widened. There are known sunroof deflectors and the like for preventing wind slops generated in the windshield (see, for example, Patent Documents 1 and 2).
JP 2004-345562 A JP 2002-52935 A

  The above-described automobile air resistance reduction device such as a rear spoiler has the following problems. That is, the rear spoiler attached to a large vehicle such as a bus requires a large one, which is expensive to manufacture and has a weight of about 50 to 100 kg.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an automobile air resistance reduction device that can improve the aerodynamic performance and reduce the size by controlling the air flow without changing the cab shape.

  In order to solve the above problems and achieve the object, the air resistance reducing device for an automobile of the present invention is configured as follows.

  (1) A guide portion that is provided at an R stop at the front end of the roof of the box-type vehicle over substantially the entire width of the box-type vehicle, guides the airflow from the front of the box-type vehicle upward, and generates a vortex of the airflow. Have.

  (2) In (1), the guide portion has an angle of approximately 45 ° from the front side to the rear upper side of the box-type vehicle and a height of approximately 10 mm.

  According to the automobile air resistance reducing device described in (1), it is possible to improve the aerodynamic performance and reduce the size by controlling the air flow without changing the cab shape.

  According to the air resistance reducing device for an automobile described in (2), a sufficient air resistance reducing effect can be obtained even if it is small.

  FIG. 1 is a perspective view showing a box-type vehicle 10 such as a bus having an air resistance reducing device for an automobile according to an embodiment of the present invention, and FIG. 2 is a side view showing a main part of the box-type vehicle 10.

  The box-type vehicle 10 includes a substantially rectangular parallelepiped body 20 and has a long shape in the front-rear direction (traveling direction). The vehicle body 20 includes a roof 21, a side surface portion 22, a front surface portion 23, and a back surface portion 24, and a vehicle compartment is formed therein. The vehicle body 20 is supported by front wheels 30 and rear wheels 31.

  An R-shaped curved surface portion 25 is formed between the roof 21 and the front surface portion 23. A plate-shaped guide member (air resistance reduction device for an automobile) 40 is attached to the boundary position between the flat roof 21 and the curved surface portion 25, that is, the R stop portion 25a, at an angle of 45 ° over substantially the entire width. The guide member 40 is made of a sheet metal having a width of about 10 mm. The guide member 40 has a function of guiding an airflow from the front of the vehicle body 20 upward and generating a vortex of the airflow.

  In the present embodiment, the sheet metal guide member 40 is used, but a similar effect can be obtained by using an extruded product made of resin or aluminum.

  Thus, the box-type vehicle 10 provided with the guide member 40 has the following effects compared to the box-type vehicle X not provided with the guide member 40. 3, 5 and 7 show the case where the guide member 40 is provided, and FIGS. 4, 6 and 8 show the case where the guide member 40 is not provided. 3 and 4 show the flow of the air flow F, FIGS. 5 and 6 show the velocity distribution of the air flow F, and FIGS. 7 and 8 show the flow direction of the air flow F on the back surface.

  In general bus aspect ratio (total height: full width) and the positional relationship from the ground to the bottom of the vehicle, the vehicle front pressure stagnation point (airflow flows up and down) below the center position in the vehicle height direction. Is located at the center position. Below the stagnation point, the airflow flows on the lower surface of the vehicle floor, and on the upper side, it flows in the roof direction. Therefore, the airflow speed of the roof is faster than that under the floor.

  Therefore, the flow along the side wall is often hindered on the side surface of the vehicle due to the influence of mirrors, window frame steps, tires, and the like, and the airflow speed is reduced.

  On the other hand, the roof generally has a flat surface, and since the deceleration is small, the airflow speed is often faster than the side airflow.

  As a result, the downflow from the rear end of the roof to the back of the vehicle is often faster than the airflow drawn from the side to the back of the vehicle, and tends to have a vortex structure developed in the downflow direction. Therefore, by providing the guide member 40 at the R stop portion 25a, as shown in FIG. 3, the airflow F in front is guided upward as the box-type vehicle 10 travels, and the separation phenomenon of the airflow F occurs. The airflow U flows on the roof 21. Therefore, the flow velocity on the roof 21 is reduced as shown in FIG. 5, the amount of the air flow F near the rear end R of the vehicle body 20 is reduced, and the left and right side portions of the vehicle body 20 are shown in FIG. The airflow F2 blown down to the back surface portion 24 is weakened by the interference with the airflow F1 that circulates from the rear end of 22. For this reason, there are few low voltage | pressure areas in the back surface part 24, the force by which the vehicle is pushed back by pressure reduction becomes weak, and Cp value decreases.

  On the other hand, in the box-type vehicle X in which the guide member 40 is not provided, as shown in FIG. 4, as the box-type vehicle X travels, the front airflow F flows rearward along the roof 21 and the airflow F The area where the flow velocity of the air flow decreases becomes narrower. For this reason, the airflow F at the rear end R of the vehicle body 20 is blown down to the back surface portion 24 without decreasing. For this reason, the airflow F2 that blows down to the back surface portion 24 due to interference with the airflow F1 that circulates from the rear end of the side surface portion 22 of the vehicle body 20 is further strengthened, the low pressure region in the back surface portion 24 is increased, and the pressure drop is increased, Cp value increases.

  FIG. 9 is a graph showing the influence of each part of the box-type vehicle 10 and the box-type vehicle X on the Cp value. Although the Cp value slightly increases because peeling occurs on the front surface of the vehicle, the Cp value decreases greatly on the back surface of the vehicle, and the Cp value decreases, for example, by about 16% as a whole.

  As described above, in the box-type vehicle 10 having the guide member 40, it is possible to reduce the airflow that flows around the back surface portion 24 of the vehicle body 20 and reduce the pressure acting on the front surface of the vehicle by reducing the low pressure region. For this reason, it becomes possible to improve aerodynamic performance, without changing a cab shape. Further, since the guide member 40 is small and can exhibit a sufficient effect, the guide member 40 is low in cost and can prevent deterioration in fuel consumption due to an increase in weight.

  FIG. 10 is a side view showing the main part of a box-type vehicle 10A having an automobile air resistance reduction device according to the second embodiment of the present invention. 10, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The box-type vehicle 10A includes a roof 21A. A guide member 40A is integrally provided at the R-stop portion 26 at the front end of the roof 21A.

  Also in the box-type vehicle 10A configured as described above, the same effects as those of the box-type vehicle 10 described above can be obtained.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

The perspective view which shows the box-type vehicle which has the air resistance reduction member of the motor vehicle based on the 1st Embodiment of this invention. The side view which shows the principal part of the box type vehicle. The side view which shows the flow of the airflow in the same box type vehicle. The side view which shows the flow of the airflow in the box-type vehicle used as a comparison object. The side view which shows the velocity distribution of the airflow in the box type vehicle. The side view which shows the velocity distribution of the airflow in the box-type vehicle used as a comparison object. The perspective view which shows the flow of the airflow in the back part of the box type vehicle. The perspective view which shows the flow of the airflow in the back part of the box-type vehicle used as a comparison object. The figure which shows the influence which each part of the box-type vehicle and a box-type vehicle has on a Cp value. The side view which shows the principal part of the box-type vehicle which has the air resistance reduction member of the motor vehicle which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,10A ... Box-type vehicle, 20 ... Car body, 21 ... Roof, 22 ... Side part, 23 ... Front part, 24 ... Back part, 25 ... Curved part, 25a ... R stop part, 40 ... Guide member (air of automobile) Resistance reduction device), X ... box type vehicle (for comparison).

Claims (2)

  It has a guide portion that is provided at the R stop portion at the front end of the roof of the box-type vehicle over substantially the entire width of the box-type vehicle, guides the airflow from the front of the box-type vehicle upward, and generates a vortex of the airflow. A device for reducing the air resistance of an automobile.   The air resistance reduction device for an automobile according to claim 1, wherein the guide portion has an angle of approximately 45 ° from the front side to the rear upper side of the box-type vehicle and a height of approximately 10 mm.

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