JP7125665B2 - vehicle rear body structure - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle rear body structure, and more particularly to a vehicle rear body structure having a spoiler covering an upper end portion of a rear window glass.

2. Description of the Related Art Conventionally, many rear spoilers have been put to practical use in order to reduce air resistance, which is a major factor in improving vehicle maneuverability and fuel efficiency.
The rear spoiler usually consists of a roof spoiler that covers the upper end portion of the rear window glass and extends in the vehicle width direction, and a pair of left and right side spoilers that extend downward from both left and right ends of the roof spoiler.

As shown in FIG. 10, in the rear area of the vehicle during travel, the airflow flowing over the upper surface of the roof (hereinafter referred to as roof airflow) is caught in the airflow flowing over the upper surface of the side wall of the vehicle body (hereinafter referred to as "sidewall airflow"). A pair of left and right trailing vortices (also called trailing vortexes) extending spirally are formed. Since the area sandwiched by these pair of wake vortices forms a negative pressure area (dead water area) where the air hardly moves, it exerts a drag force to move the vehicle backward, resulting in a kinetic energy loss. is a major factor in
The rear spoiler has the function of suppressing (reducing) wake vortices generated behind the vehicle by using the roof spoiler and side spoilers to pull off the roof airflow and side wall airflow from the vehicle body at once.

The vehicle rear body structure of Patent Document 1 includes a roof spoiler extending in the vehicle width direction, and a pair of left and right side spoilers extending downward from both left and right ends of the roof spoiler. In addition, an outer ridge portion for side wall air flow separation is vertically extended to form an extension portion having an inner ridge portion and extending rearward inward of the projection of the ridge portion in the vehicle width direction. As a result, the outer ridge immediately separates the sidewall airflow, and the inner ridge separates the inward crosswind, improving the aerodynamic characteristics.

JP 2017-087871 A

The rear body structure of the automobile of Patent Document 1 can improve the aerodynamic characteristics by immediately separating the side wall airflow from the outer ridge line.
However, when the rear side edge of the side spoiler is formed so as to move downward toward the rear side as in Patent Document 1, there is a possibility that the kinetic energy loss cannot be sufficiently reduced.

As a result of investigation by the present inventor, it was found that a wake vortex is generated based on the speed difference between the high-speed roof airflow and the low-speed side wall airflow, and that the greater the speed difference between these airflows, the larger (strong) the wake vortex. .
In other words, as the side wall airflow flowing rearward near the roof side rail gradually separates from the upper end to the lower end of the rear edge of the side spoiler, the flow velocity of the side wall airflow gradually decreases, resulting in a decrease in flow velocity. As a result, the side wall airflow that is caught in the roof airflow increases, and as a result, the effect of suppressing the formation of wake vortices is reduced.
Therefore, in order to ensure the effect of suppressing the generation of trailing vortices that cause running resistance, the rear body structure of the vehicle needs to be further improved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle rear body structure and the like capable of reducing running resistance caused by trailing vortices generated behind the vehicle.

According to claim 1, there is provided a vehicle rear body structure having a rear window glass, a spoiler covering an upper end portion of the rear window glass, and a lift gate capable of opening and closing a rear luggage compartment opening. , the spoiler has a roof spoiler extending in the vehicle width direction, and a pair of left and right side spoilers extending downward from both left and right ends of the roof spoiler, and the rear side edges of the side spoilers extend downward from the rear window. A pair of left and right roof side rails extending in the longitudinal direction of the vehicle are formed so as to extend upward from the middle portion of the end portion of the glass in the vehicle width direction and substantially orthogonal to the longitudinal direction of the vehicle body, and the pair of roofs. The side rails each include a roof side rail outer disposed on the vehicle width direction outer side, and a roof side rail inner forming a closed cross section extending in the vehicle front-rear direction in cooperation with the roof side rail outer, and the roof side. A groove portion extending in the vehicle width direction and recessed inward in the vehicle width direction is formed in the outer portion of the rail outer in the vehicle width direction, and the rear edge portion of the groove portion and the front edge portion of the side spoiler are continuous in the vehicle length direction. The side spoiler is arranged in the

In this vehicle rear body structure, since the spoiler has a roof spoiler extending in the vehicle width direction and a pair of left and right side spoilers extending downward from both left and right ends of the roof spoiler, the spoiler acts on the rear window glass. It is possible to separate the roof airflow flowing on the upper surface of the roof from the rear edge of the roof spoiler and separate the side wall airflow flowing on the upper surface of the side wall of the vehicle body from the rear edge of the side spoiler while reducing lift and drag.
Since the rear edge of the side spoiler extends upward from the middle step of the end of the rear window glass in the vehicle width direction and is formed to be substantially perpendicular to the front-rear direction of the vehicle body, the air flows near the roof side rails. By separating the side wall air currents from the vehicle body substantially at the same time, it is possible to suppress a decrease in the flow velocity and reduce the side wall air currents that are caught in the roof air current.
In addition, since the side wall air currents flowing in the vicinity of the roof side rails are collected via the grooves, the side wall air currents increase in velocity before the side wall air currents reach the rear edge of the side spoiler. The difference can be reduced and the collective sidewall airflow can be forced to the rear edge of the side spoiler.

The invention of claim 2 is characterized in that, in the invention of claim 1, an upper end portion of the rear side edge portion is disposed forward of a rear end portion of the roof spoiler.
According to this configuration, the separation timing of the side wall air current can be made earlier than the separation timing of the roof air current, and the side wall air current that is involved in the roof air current can be further reduced.

The invention of claim 3 is the invention of claim 1 or 2 , wherein the rear side edge has a distance from a predetermined reference point set at the rear of the vehicle to the upper end and a distance from the reference point to the lower end. The reference point is an attachment point where the airflow passing through the vehicle converges, and is the outermost position in the vehicle width direction of the vehicle center line in the vehicle width direction on the waist line of the vehicle. It is characterized in that it is set at a point where the crossing angle with the line passing through it is about 16 degrees .
With this configuration, the angle of the rear edge of the side spoiler can be easily set.

The invention according to claim 4 is the invention according to any one of claims 1 to 3 , wherein the rear edge separates a roof airflow flowing over the upper surface of the vehicle body roof and a side wall airflow flowing over the upper surface of the vehicle body side wall as the vehicle travels. It is characterized by being formed as
According to this configuration, the sidewall airflow and the roof airflow can be reliably separated, and the influence of the trailing vortex can be suppressed.
The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the groove is formed such that the width in the vertical direction increases toward the rear side in the vehicle body front-rear direction, and the lower end portion of the rear edge of the groove portion is located below a substantially central position of the front side edge of the side spoiler in the vertical direction of the vehicle body.
According to this configuration, the running resistance can be further reduced.

According to the vehicle rear body structure of the present invention, it is possible to reduce the running resistance caused by wake vortices generated behind the vehicle.

1 is a perspective view of a rear body structure of a vehicle according to Embodiment 1; FIG. It is a left side view. It is a top view. FIG. 3 is a sectional view taken along line IV-IV of FIG. 2; FIG. 2 is an enlarged view of a main portion of FIG. 1; FIG. 4 is a perspective view of a rear spoiler; FIG. 5 is an explanatory diagram of a setting method related to the rear edge of the side spoiler; It is an analysis result of the back airflow concerning a comparative example model. It is an analysis result of the back airflow concerning an example model. FIG. 4 is an explanatory diagram of trailing vortices;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or uses.

Embodiment 1 of the present invention will be described below with reference to FIGS. 1 to 9. FIG.
As shown in FIGS. 1 to 3, the vehicle V of this embodiment is a four-door hatchback passenger car having a flip-up lift gate 1 at the rear portion of the vehicle body.
In the following description, the direction of arrow F is the front side, the direction of arrow L is the left side, and the direction of arrow U is the upper side.

First, the basic configuration of the vehicle V will be described.
As shown in FIGS. 1 to 3, this vehicle V has a pair of left and right front pillars 2 that support the front windshield, a pair of left and right center pillars (not shown), and a pair of left and right rear pillars 3. The roof part 4 is supported by these pillars.
A front door 5 is rotatably supported between the front pillar 2 and the center pillar, and a rear door 6 is rotatably supported between the center pillar and the rear pillar 3 .

A front fender 7 connected to the front pillar 2 is arranged in a front lower portion of the front pillar 2 , and a rear fender 8 connected to the rear pillar 3 is arranged in a rear lower region of the rear pillar 3 . A pair of left and right side panels S corresponding to side walls of the vehicle V are composed of the outer panels of the front pillar 2, the rear pillar 3, the front door 5, the rear door 6, the front fender 7, and the rear fender 8. As shown in FIG.

The roof portion 4 includes a pair of left and right roof side rails 9 extending in the front-rear direction, a front header (not shown) connecting the front ends of the pair of roof side rails 9 to each other, and a rear portion of the pair of roof side rails 9 . It is provided with a rear header (not shown) that connects the ends together, and a substantially rectangular roof panel 10 that covers the entire area between the pair of roof side rails 9 from above.

As shown in FIG. 3 , the pair of roof side rails 9 are formed so that the separation distance in the vehicle width direction becomes narrower toward the rear.
As shown in FIG. 4, the roof side rail 9 includes a roof side outer 9a arranged on the outer side in the vehicle width direction, and a roof side inner 9b forming a closed cross section extending longitudinally in cooperation with the roof side outer 9a. have. An extension line L connecting the centroids of the closed cross section is formed in a gently curved shape so as to move downward from the upper end portion of the front pillar 2 toward the rear side.
As shown in FIGS. 1 to 5, the upper half of the roof side outer 9a has a groove 9g extending forward and backward along the extension line L. As shown in FIGS. The groove portion 9g is formed so that the vertical dimension (vertical width) and the depth dimension become larger (the distance to the centroid becomes shorter) toward the rear side.

Next, the lift gate 1 will be explained.
As shown in FIGS. 1 to 3, the lift gate 1 is configured to open and close the rear luggage compartment opening. The lift gate 1 includes a metal inner panel (not shown), a metal outer panel 11, a pair of left and right rear pillar reinforcements (not shown), a rear window glass 12, and a synthetic resin (for example, polycarbonate resin). , ABS, etc.), and is formed in a substantially curved shape when viewed from the side.
The outer panel 11 constitutes the outer surface of the lift gate 1 except for the upper end portion, and is equipped with an inner lamp portion of a rear combination lamp, a rear wiper mechanism, and the like.

Next, the spoiler 20 will be explained.
The spoiler 20 forms part of the outer surface of the lift gate 1 in cooperation with the outer panel 11 so as to cover the upper end portion of the rear window glass 12 .
As shown in FIGS. 1 to 3, 5, and 6, the spoiler 20 includes a substantially horizontal roof spoiler 21 and a pair of substantially vertical side walls extending downward from both left and right ends of the roof spoiler 21. It has a spoiler 22 .

As shown in FIG. 2, the roof spoiler 21 projects rearward from the rear end portion of the roof panel 10 in a side view. The top surface of the roof spoiler 21 continues to the top surface of the roof panel 10 without forming an intersection angle, and the vertical distance from the rear window glass 12 increases toward the rear.
At the rear of the roof spoiler 21, a high-mounted stop lamp is equipped that lights in synchronization with the stop lamp of the rear combination lamp.

As shown in FIG. 3 , both left and right ends of the roof spoiler 21 are formed in a substantially curved shape along extension lines of the left and right ends of the roof panel 10 in a plan view. A rear side edge portion 21e of the roof spoiler 21 extending in the vehicle width direction is formed along the lower end portion of the rear window glass 12, and the center portion is arranged at the rearmost side compared to the left and right end portions.
As a result, the roof air current flowing over the upper surface of the roof panel 10 is separated from the rear edge 21e of the roof spoiler 21, thereby reducing lift and drag caused by the roof air current flowing over the upper surface of the rear window glass 12.

As shown in FIGS. 1 to 3, 5 and 6, the pair of side spoilers 22 are each configured in a substantially triangular shape when viewed from the side.
A front edge portion 22f and a rear edge portion 22e of the side spoiler 22 are respectively formed so as to correspond (overlap) on a rear extension line of the groove portion 9g of the roof side rail 9. As shown in FIG.
The upper end portion 22a of the rear side edge portion 22e is disposed at a position on the front side of the lower end portion 22b and on the front side of the rear end portion of the rear side edge portion 21e in a side view.
In this embodiment, the lower end portion 22b and the rear end portion of the rear side edge portion 21e are arranged at approximately the same position in the front-rear direction.

The substantially linear rear edge portion 22e extends upward from the middle stage portion of the left and right end portions of the rear window glass 12 and is formed substantially orthogonal to the front-rear direction.
In this embodiment, substantially perpendicular to each other includes an angle range of 75° to 90° in consideration of design conditions, tolerances, and the like.

Here, a method for setting the rear edge portion 22e will be described.
The rear edge portion 22e has a distance La from the reference point B to the upper end portion 22a and a distance Lb from the reference point B to the lower end portion 22b. The positions of the upper end portion 22a and the lower end portion 22b are set so that .
Specifically, as shown in FIGS. 7(a) and 7(b), on the waist line (the height position of approximately 60% of the vehicle height), the center line in the vehicle width direction and the outermost in the vehicle width direction A reference point B is set at an angle of approximately 16° with a line passing through the position. The upper end portion 22a and the lower end portion 22b are set at positions equidistant from the reference point B. As shown in FIG.

Next, the operation and effects of the rear body structure of the vehicle will be described.
In order to explain the actions and effects, a three-dimensional CFD (Computational Fluid Dynamics) model calculated based on CAD (Computer Aided Design) data was created and a verification experiment was conducted. In this verification experiment, an example model with the same specifications as in Example 1 and a comparative example model with the same specifications as in Example 1 except that the angle of inclination of the rear edge of the side spoiler is 30° were prepared. Each airflow was analyzed. It should be noted that the same reference numerals as in the first embodiment will be used to describe the same configurations as in the first embodiment.

8 and 9 show the analysis results.
As shown in FIG. 8 , in the comparative example model, the main stream of side wall air currents (main side wall air currents) flowing over the middle stage of the left and right side panels S is caught in the roof air currents flowing over the roof panel 10 .
As a result, the left and right main side wall airflows are combined with the roof airflow to generate turbulence in the airflow behind the vehicle body, that is, a pair of left and right main wake vortices.

The left and right side wall airflows (upper side wall airflows) respectively flowing over the side panel S near the left and right roof side rails 9 are gradually separated from the vehicle body with a time lag by the rear edge of the side spoiler, so the speed decreases. Then, a movement vector in the turning direction is given.
As a result, the upper side wall air currents that have started spiral motion are caught in the roof air currents flowing over the roof panel 10, and a pair of left and right upper wake vortices are generated above the main wake vortex.
A negative pressure area (dead water area) where air does not move is formed between the trailing vortices, and the magnitude of the negative pressure tends to increase as the trailing vortex increases.

As shown in FIG. 9, in the embodiment model, the left and right main side wall airflows are combined with the roof airflow to generate a pair of left and right main wake vortices in the same way as in the comparative example model.
The left and right upper side wall airflows flowing in the vicinity of the roof side rail 9 are separated from the vehicle body by the rear edge 22e of the side spoiler 22 at the same time, so that the speed reduction is small and the spiral motion after separation is suppressed. Therefore, since the upper side wall airflow that is caught in the roof airflow is suppressed, the pair of left and right upper wake vortices generated above the main wake vortex is smaller than in the comparative example model.

Furthermore, the side wall airflow flowing near the side rail 9 is converged by the groove 9g, so that it is guided to the rear side edge 22e of the side spoiler 22 while suppressing a decrease in flow velocity.
This avoids a decrease in the flow velocity of the upper side wall airflow flowing in the vicinity of the side rail 9 from the upstream side to the downstream side of the rear edge portion 22e, thereby suppressing turbulence of the airflow.
From the above, it was found that the example model has a higher effect of suppressing the generation of trailing vortices than the comparative example model.

According to this rear vehicle body structure, the spoiler 20 has a roof spoiler 21 extending in the left and right direction, and a pair of left and right side spoilers 22 extending downward from both right and left ends of the roof spoiler 21 . While reducing the lift and drag, the roof airflow flowing on the upper surface of the roof panel 10 is separated from the rear edge 21e of the roof spoiler 21, and the side wall airflow flowing on the upper surface of the side panel S is separated from the rear edge of the side spoiler 22. 22e. The rear side edge portion 22e of the side spoiler 22 extends upward from the middle portion of the left and right ends of the rear window glass 12 and is formed to be substantially perpendicular to the longitudinal direction of the vehicle body. By separating the flowing side wall air currents from the vehicle body substantially at the same time, a decrease in flow velocity can be suppressed, and the side wall air currents caught in the roof air current can be reduced.

Since the upper end portion 22a of the rear side edge portion 22e is arranged on the front side of the rear end portion of the roof spoiler 21, the separation timing of the side wall airflow can be made earlier than the separation timing of the roof airflow. It is possible to reduce the side wall airflow entrained in the

A pair of left and right roof side rails 9 extending in the front-rear direction are provided, and a groove portion 9g recessed inward in the vehicle width direction extending in the front-rear direction is formed in the outer portion of the roof side rail 9 in the vehicle width direction. A side spoiler 22 is arranged in the .
As a result, the side wall air currents flowing near the roof side rails 9 are collected through the grooves 9g, so that the side wall air currents are increased in velocity before reaching the rear edge 22e of the side spoiler 22, and the roof is closed. The velocity difference between the airflow and the side wall airflow can be reduced, and the collected side wall airflow can be forcibly guided to the rear edge 22e of the side spoiler 22. FIG.

The rear edge portion 22e is formed such that the distance from a predetermined reference point B set behind the vehicle V to the upper end portion 22a and the distance from the reference point B to the lower end portion 22b are substantially equal. The angle of the rear side edge 22e of the side spoiler 22 can be easily set.

The rear edge portion 22e is formed so as to separate the roof airflow flowing over the upper surface of the roof panel 10 and the side wall airflow flowing over the upper surface of the side panel S as the vehicle travels, so that the side wall airflow and the roof airflow are reliably separated from each other. It can be divided, and the influence of trailing vortices can be suppressed.

Next, a modified example in which the above embodiment is partially changed will be described.
1) In the above embodiment, an example of a hatchback type passenger car was explained, but a sedan type passenger car may be used, and the present invention can be applied regardless of the type of vehicle.

2) In the above embodiment, the rear spoiler is also used as the outer panel of the lift gate.

3) In addition, those skilled in the art can implement various modifications to the above-described embodiment or combinations of the embodiments without departing from the scope of the present invention. Any modifications are also included.

1 Lift gate 9 Roof side rail 9g Groove 10 Roof panel 12 Rear window glass 20 Rear spoiler 21 Roof spoiler 22 Side spoiler 22e Rear edge V Vehicle B Reference point

Claims (5)

In a vehicle rear body structure having a rear window glass and a spoiler covering an upper end portion of the rear window glass, and equipped with a lift gate capable of opening and closing a rear luggage compartment opening,
The spoiler has a roof spoiler extending in the vehicle width direction, and a pair of left and right side spoilers extending downward from both left and right ends of the roof spoiler,
a rear edge portion of the side spoiler extends upward from a middle step portion of an end portion of the rear window glass in the vehicle width direction and is formed to be substantially perpendicular to the front-rear direction of the vehicle body ;
Having a pair of left and right roof side rails extending in the longitudinal direction of the vehicle body,
Each of the pair of roof side rails includes a roof side rail outer disposed outside in the vehicle width direction and a roof side rail inner forming a closed cross section extending in the vehicle longitudinal direction in cooperation with the roof side rail outer. prepared,
A groove extending in the front-rear direction and recessed inward in the vehicle width direction is formed in the vehicle width direction outer portion of the roof side rail outer,
1. A rear vehicle body structure for a vehicle , wherein said side spoiler is arranged so that a rear edge of said groove and a front edge of said side spoiler are continuous in the longitudinal direction of the vehicle body. 2. The rear body structure of a vehicle according to claim 1, wherein an upper end portion of said rear edge portion is disposed forward of a rear end portion of said roof spoiler. The rear edge is formed such that the distance from a predetermined reference point set at the rear of the vehicle to the upper end is substantially equal to the distance from the reference point to the lower end,
The reference point is an attachment point where airflow passing through the vehicle converges, and the intersection angle between the vehicle center line in the vehicle width direction and the line passing through the outermost position in the vehicle width direction on the waist line of the vehicle is approximately 3. The rear body structure of a vehicle according to claim 1, wherein the angle is set at a point of 16 degrees . 4. The vehicle according to any one of claims 1 to 3, wherein the rear edge portion is formed so as to separate a roof airflow flowing over the upper surface of the vehicle body roof and a side wall airflow flowing over the upper surface of the side wall of the vehicle body as the vehicle travels. Rear body structure of the described vehicle. The groove portion is formed to have a larger width in the vertical direction toward the rear side in the longitudinal direction of the vehicle body,
5. The lower end of the rear edge of the groove is positioned below a substantially central position of the front edge of the side spoiler in the vertical direction of the vehicle body. vehicle rear body structure.

Images