JPH07215073A - Undercover rear part structure for vehicle - Google Patents

Abstract

PURPOSE:To reduce air resistance and suppress the temperature rise in the vicinity of a muffler, as to the undercover rear part structure of a vehicle. CONSTITUTION:At the rear part of a rear undercover 24 arranged on the undersurface of an automobile body 10, an inclined surface 24B which is gently inclined over a vehicle toward the vehicle rear end part is formed. On the inclined surface 24B, an opened port part 42 is formed, and the vicinity of the rear end part 36A of a muffler 36 projects outside the automobile body 10 from the opened port part 42. Accordingly, the applied air resistance is reduced by the vicinity of the rear end part 36A of the muffler 36 which projects from the opened port part 42, and the max. temperature in the vicinity of the muffler 36 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle undercover rear structure having an undercover for covering an underfloor.

[0002]

2. Description of the Related Art Conventionally, a rear structure of an undercover of a vehicle provided with an undercover for covering an underfloor has been known. Figure 7
As shown in, in the rear structure of the undercover of this vehicle, the undercover 72 is attached to the lower surface side of the floor panel of the vehicle body 70.
By covering the floor panel from below, the flow of air through the lower part of the vehicle body is made smooth and the air resistance is reduced.

[0003]

However, in the rear structure of the undercover of this vehicle, the entire muffler 74 is covered with the undercover 72 as shown in FIG. 8 in order to reduce the air resistance as much as possible. Only the mouth 76 is inserted into the through hole 78 formed in the under cover 72. Therefore, in the rear structure of the under cover of this vehicle, the heat radiation performance in the vicinity of the muffler 74 is low, and the temperature in the vicinity of the muffler 74 is likely to rise significantly while the vehicle is traveling and after the vehicle is stopped. May cause harm.

In view of the above facts, it is an object of the present invention to obtain a vehicle undercover rear structure capable of reducing air resistance by the undercover and suppressing a temperature rise near the muffler.

[0005]

According to the present invention, there is provided an undercover rear structure for a vehicle, comprising an undercover which has an inclined surface gently inclined upward toward a vehicle rear end and covers an underfloor of the vehicle. It is characterized by including an opening formed on the inclined surface of the under cover, and a muffler that extends substantially horizontally in the rear part of the vehicle and a part of which projects from the opening.

[0006]

In the vehicle undercover rear structure of the present invention,
An opening is formed on an inclined surface that is formed in an undercover that covers the underfloor of the vehicle and that is gently inclined upward toward the vehicle toward the rear end of the vehicle. From this opening, a muffler that extends substantially horizontally at the rear of the vehicle. A part of it is protruding. Therefore, the air flow that flows along the lower side of the under cover receives a small air resistance due to a part of the muffler protruding from the opening, and the air resistance can be reduced by the under cover.

Further, while the vehicle is traveling, a part of the muffler is cooled by the air flow flowing below the under cover, and while the vehicle is stopped, the radiant heat is efficiently dissipated in the part of the muffler. Therefore, the temperature rise around the muffler can be suppressed. Therefore, it is difficult to give heat damage to the muffler and its peripheral parts.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the vehicle undercover rear structure of the present invention will be described with reference to FIGS.

In the figure, an arrow FR indicates a vehicle front direction, an arrow IN indicates a vehicle width inner direction, and an arrow UP indicates a vehicle upward direction.

As shown in FIG. 1, an under cover 12 is provided at the bottom of the automobile body 10.

As shown in FIG. 6, the undercover 12 includes a front undercover 16 which covers the lower part of the engine compartment, a center undercover 20 which is located below the passenger compartment, and a rear undercover which is located below the luggage box. It is composed of 24 sheets.

As shown in FIG. 5, the rear under cover 24 is arranged below the rear floor pan 26.
On a lower surface 26A of the rear floor pan 26, there is provided an under-lean force 32 which extends in the vehicle front-rear direction at a predetermined interval in the vehicle width direction.

Under Reinforcement 3
2 has a U-shaped cross-section viewed from the vehicle front-rear direction with the opening facing upward. A flange 32B is formed at an upper end portion of the inner side wall portion 32A of the under lean reinforcement 32 toward the inner side in the vehicle width direction, and a flange 32B is formed at an upper end portion of the outer side wall portion 32C of the under lean reinforcement 32 in the vehicle width direction A flange 32D is formed toward the outside. These flanges 32B and 32D are welded to the lower surface 26A of the rear floor pan 26, respectively. Therefore, the under-reinforcement 32 and the rear floor pan 26 form a closed-section rear portion structure extending in the vehicle front-rear direction.

Also, the under lean reinforcement 32
The mounting wall portion 32 </ b> E has a plurality of mounting holes 33 formed at predetermined intervals along the vehicle front-rear direction.
On the upper surface of E, the weld nut 3 is coaxial with the through hole 33.
5 is fixed.

At a portion of the upper surface 24A of the rear under cover 24 facing the under lean reinforcement 32,
An undercover reinforcement 54 extending in the vehicle front-rear direction is provided. The cross-sectional shape of the undercover reinforcement 54 viewed from the vehicle front-rear direction is a U-shape with the opening portion facing downward. Inner wall portion 54 of reinforcement 54 for undercover
At the lower end of A, the flange 54B is directed inward in the vehicle width direction.
And a flange 54D is formed at the lower end of the outer wall portion 54C of the undercover reinforcement 54 toward the vehicle width direction outer side. These flanges 54B and 54D are welded to the upper surface 24A of the rear under cover 24, respectively.

Further, through holes 56 are formed in the mounting wall portion 54E of the undercover reinforcement 54 at predetermined intervals along the vehicle front-rear direction. These through holes 56 are coaxial with the mounting holes 33, and the rear under cover 24 can be fixed to the lower surface 26A of the rear floor pan 26 by screwing the inserted bolt 58 into the weld nut 35. There is.

Further, a working hole 60 for mounting the bolt 58 is formed in a portion of the rear under cover 24 facing the through hole 56. The work hole 60 is closed by a lid 22 made of a rubber material so that water, dust and the like do not enter between the undercover reinforcement 54 and the rear undercover 24.

As shown in FIG. 2, the rear portion of the rear under cover 24 has an inclined surface 24B which is gently inclined upward toward the vehicle toward the rear end of the vehicle. This inclined surface 24
The rear end of B reaches the lower end of the rear bumper 40.
An opening 42 is formed near the rear end of the inclined surface 24B of the rear under cover 24.
The shape of No. 2 viewed from the rear of the vehicle is as shown in FIG.

As shown in FIG. 2, the exhaust pipe 34, the muffler 36, and the tail pipe 38 are connected to the exhaust pipe 34, the muffler 36, and the tail pipe 38 in this order from the front of the vehicle. The muffler 36 extends horizontally, and a part of the muffler 36 near the rear end 36A projects from the opening 42 to the outside of the vehicle body 10.

The relationship between the protrusion amount H of the muffler 36 from the rear under cover 24, the air resistance C _D of the muffler 36 and the maximum temperature T near the muffler 36 is as shown in FIG. Decreases as the protrusion margin H of the muffler 36 increases, and becomes substantially constant when the protrusion margin H exceeds a predetermined value H ₁ . Further, the air resistance C _D decreases with a decrease in the protrusion allowance H of the muffler 36, and becomes substantially constant when the protrusion allowance H becomes smaller than a predetermined value H ₂ . This is because near the lower surface of the rear under cover 24, a velocity boundary layer in which the flow velocity of the air flow due to traveling is low is formed within a range of several tens of mm from the surface, and the rear end portion 36A of the muffler 36 is located within this range. This is because even if it is projected, it does not cause an increase in air resistance. Also, H ₁ <H ₂ .

Therefore, the protrusion margin H of the muffler 36 is set to H ₁ <H <H ₂ , which is the optimum range in which the air resistance C _D can be reduced and the maximum temperature T can be lowered.

Next, the operation of this embodiment will be described. In the vehicle undercover rear portion structure of the present embodiment, the inclined surface 24B is formed at the rear portion of the rear undercover 24 that covers the lower surface 26A of the rear floor pan 26, so the air flow ( 2 arrow W)
In the rear part of the rear under cover 24,
Flow smoothly toward the rear of the vehicle.

It should be noted that the vicinity of the rear end portion 36A of the muffler 36, which extends substantially horizontally in the rear portion of the vehicle, protrudes from the opening 42, but the protrusion margin H of the muffler 36 is H <H ₂ . The air flow flowing along the lower side of the rear under cover 24 receives a small air resistance near the rear end portion 36A of the muffler 36 protruding from the opening 42, and the rear under cover 24 can reduce the air resistance.

Further, the vicinity of the rear end portion 36A of the muffler 36 projects from the opening 42, and the projection margin H of the muffler 36 is H ₁ <H. Therefore, while the vehicle is traveling, the vicinity of the rear end portion 36A of the muffler 36 is cooled by the air flow flowing below the rear under cover 24, and the rear end portion 36A of the muffler 36 is stopped while the vehicle is stopped.
Radiant heat is efficiently dissipated in the vicinity, so
As shown in FIG. 4, the temperature rise near the muffler can be suppressed. Therefore, there is no risk of heat damage to the muffler and peripheral parts such as the vibration-proof rubber.

Further, in this embodiment, since the vicinity of the rear end portion 36A of the muffler 36 is projected below the rear under cover 24, the volume of the luggage room can be increased.

In the above, the present invention has been described in detail with respect to specific embodiments, but the present invention is not limited to such embodiments, and various other embodiments within the scope of the present invention. It is obvious to a person skilled in the art that
For example, the shape of the opening 42 is not limited to the shape shown in FIG. In addition, in the present embodiment, the vicinity of the rear end portion 36A of the muffler 36 horizontally projects from the opening 42, but the vicinity of the rear end portion 36A of the muffler 36 is slightly inclined from the opening 42 with respect to the horizontal direction. You may make it protrude.
Further, the vicinity of the front end portion or the vicinity of the intermediate portion as a part of the muffler 36 may be projected from the opening 42.

[0027]

INDUSTRIAL APPLICABILITY The present invention provides an undercover rear structure for a vehicle having an inclined surface that is gently inclined upward toward the vehicle toward the rear end of the vehicle and that covers the underfloor of the vehicle. Since it has a configuration in which the opening formed in the vehicle and a muffler that extends substantially horizontally in the rear part of the vehicle and a part of which projects from the opening, the under cover can reduce the air resistance, and the vicinity of the muffler. It has an excellent effect that it is possible to suppress the temperature rise.

[Brief description of drawings]

FIG. 1 is a perspective view of a rear structure of an undercover of a vehicle according to an exemplary embodiment of the present invention, as viewed from diagonally below the vehicle rear side.

FIG. 2 is a side sectional view showing the rear structure of the undercover of the vehicle according to the embodiment of the present invention.

FIG. 3 is a front view of the opening of the undercover rear portion structure of the vehicle according to the embodiment of the present invention, as viewed from the rear of the vehicle.

FIG. 4 is a graph showing the relationship between the protrusion amount of the muffler of the vehicle undercover rear structure and the air resistance and the maximum temperature around the muffler according to one embodiment of the present invention.

FIG. 5 is a partially enlarged cross-sectional view showing a rear structure of an undercover of a vehicle according to an embodiment of the present invention as seen from the front of the vehicle.

FIG. 6 is a perspective view of an undercover of a vehicle to which a vehicle undercover rear structure according to an exemplary embodiment of the present invention is applied, as viewed from obliquely above the vehicle rear side.

FIG. 7 is a perspective view showing a structure of a rear portion of an undercover of a vehicle of a conventional example, as seen from obliquely below the vehicle rear side.

FIG. 8 is a side sectional view showing a rear structure of an undercover of a conventional vehicle.

[Explanation of symbols]

 10 Car Body 12 Undercover 24 Rear Undercover 24B Inclined Surface 36 Muffler 36A Rear End (Part) 42 Opening

Claims (1)

[Claims] 1. An undercover rear structure for a vehicle, comprising an inclined surface that is gently inclined upward toward the vehicle rear end and covers an underfloor of the vehicle.
An undercover rear structure for a vehicle, comprising: an opening formed on an inclined surface of the undercover; and a muffler that extends substantially horizontally at a rear part of the vehicle and a part of which projects from the opening.