JPH09193839A - Under floor structure of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cooling effect of the heat generation part of a floor lower side central part by gathering the under floor flow running in the lower side of an under cover to a rear floor lower side central part positively so as to increase a flow rate. SOLUTION: A nozzle 9 having a nozzle throat part 10 on the front end part between a road surface G from a front end part toward a rear side is formed on right/left both side parts of an under cover 1 and also an under floor flow shrinkage surface 2, 2 for forming a heat exhaust port 4, whose rear end is released, for flowing out the heat in a drive part mounting room E.R is recessed and an under floor flow gathering part 3 from the front end part of the under cover 1 central part across its rear end is formed between them. Therefore, the under floor flow is squeezed by both sides nozzle throat parts 10, 10 and gathered to the under floor flow gathering part 4 of the central part and the gathering of the under floor flow to the floor lower side central part is carried out positively and also the flow rate is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle underfloor structure.

[0002]

2. Description of the Related Art As an underfloor structure for an automobile, the applicant of the present invention, as disclosed in Japanese Unexamined Patent Publication No. Hei 5-330457, discloses the underside of an undercover that closes the underside of the engine room from both sides of the engine room. By discharging the hot air inside toward the rear wheels, the underfloor flow of the air flow along the lower side of the undercover is contracted between these left and right hot air discharge parts, and installed under the floor behind the undercover. An underfloor structure is proposed in which the generated heat is directed toward a heat generating portion such as a transmission, a propeller shaft, a rear differential, etc., and the heat generating portion can be efficiently cooled.

[0003]

In this conventional underfloor structure, as described above, from the hot air discharge parts on both sides of the rear end of the undercover, a pressure higher than that of the high-speed underfloor flow under the undercover is high. Since the hot air of the underflow flows out, it is possible to focus the underfloor flow between these hot air discharge parts at the rear end of the undercover, and the underfloor flow can be directed at high speed toward the heat generating part in the center under the floor behind the undercover. It can be supplied to cool the heat generating portion.

However, since the underfloor flow is focused between the hot air discharge parts on both left and right sides of the rear end of the undercover and by the air curtain of high-pressure hot air flowing out from these hot air discharge parts, the underfloor flow floor. The focusing action to the lower central portion tends to be negative, and the underfloor flow is easily affected by structures such as the front bumper, so in order to ideally focus the underfloor flow to the lower central portion of the floor, A more aggressive underfloor flow focusing function is desired.

Therefore, according to the present invention, the underfloor flow flowing under the undercover can be positively focused on the rear center of the lower floor, and the flow rate of the underfloor flow converged on the lower center of the floor can be increased. The present invention provides an underfloor structure for an automobile, in which the cooling effect of the heat generating portion arranged in the central portion on the lower side of the floor can be further enhanced.

[0006]

According to a first aspect of the present invention, the lower side of the drive unit mounting room, which is separated from the front portion of the vehicle body, is closed by a flat plate-shaped under cover, and the left and right side portions of the under cover are closed. Underfloor that forms a nozzle with a nozzle throat part at the front end part from the front end part to the rear with the road surface and forms a hot air discharge port that opens the rear end and discharges hot air in the drive unit mounting room It is characterized in that the flow constricting surface is recessed and an underfloor flow converging portion is formed between the underfloor flow converging surfaces from the front end portion to the rear end of the central portion of the undercover.

According to this structure, the nozzles are formed in the front-rear direction between the road surface and the underfloor flow contraction surface on both the left and right sides of the undercover, and moreover, below the front end portion of the underfloor flow contraction surface. A nozzle throat part is formed in the underfloor flow that flows in from the front of the vehicle and is throttled by the nozzle throat part below both front end parts of the undercover to increase the flow velocity in the entire nozzle. The underfloor flow is collected at the front part of the, and the flow rate of the underfloor flow flowing backward at a high speed along the underfloor flow converging part is increased.

As a result, the underfloor flow is positively focused to the central portion on the lower floor side behind the underfloor flow converging portion, and the cooling effect of the heat generating portion in the central portion on the lower floor side is enhanced.

Further, since the rear end of the nozzle is a hot air discharge port, the high pressure hot air in the drive unit mounting room is generated by the negative pressure generated near the hot air discharge port by the high-speed underfloor flow flowing through the nozzle. Actively discharged from the hot air outlet,
When the high-pressure hot air in the drive unit mounting room flows out from the hot-air outlet, the high-pressure hot air serves as an air curtain to promote the converging action of the underfloor flow in the lower central portion of the floor, thereby cooling the heat generating portion. Can be performed more effectively.

Moreover, since hot air in the drive unit mounting room is positively discharged from the hot air outlet in this manner, air is positively introduced into the cooler arranged in the drive unit mounting room. Then, the cooling effect of the cooler can be enhanced.

According to a second aspect of the present invention, the nozzle throat portion is formed below the rear portion of the cooler arranged at the front end of the underfloor flow constricting surface according to the first aspect of the present invention. It is characterized in that it is formed in a curved shape, and a second hot air outlet for letting out hot air in the drive unit mounting room is provided in a portion corresponding to the nozzle throat portion of the under-floor flow contracting surface.

According to the second aspect of the present invention, the second hot air exhaust port is provided in the portion corresponding to the nozzle throat portion where the pressure difference between the inner pressure of the drive unit mounting room and the rear lower side of the cooler becomes maximum. Therefore, the hot air that has passed through the cooler is positively discharged from the second hot air discharge port by the large pressure difference between the nozzle throat portion where a large negative pressure value is generated and the high pressure inside the drive unit mounting room. Since it can be caused to flow out to promote the introduction of air into the cooler, the cooling effect of the cooler can be further enhanced.

Further, the high-pressure hot air flowing out from the second hot-air outlet serves as an air curtain, so that the underfloor flow converging action at the central underfloor flow converging portion can be promoted.

A third aspect of the present invention is characterized in that an air spoiler portion that projects downward is formed at the front edge of the second hot air outlet according to the second aspect.

According to the third aspect of the present invention, the underfloor flow is further narrowed downward immediately before the second hot air outlet by the air spoiler section to further increase the differential pressure from the internal pressure of the drive unit mounting room. The amount of hot air discharged from the second hot air discharge port can be increased.

According to a fourth aspect of the present invention, the nozzle throat portion is formed below the cooler having the front end portion of the under-floor flow constricting surface according to the first aspect of the present invention arranged in the front portion of the drive unit mounting room. A second hot air that is formed in a curved shape and that is bulged to the drive unit mounting room side at the portion corresponding to the nozzle throat portion of the underfloor flow contraction surface to let the front end flow out the hot air in the drive unit mounting room. It is characterized by providing a side wedge-shaped air chamber in which the upper wall is formed to be inclined rearward and downward in addition to serving as an outlet.

According to the fourth aspect of the invention, the second hot air at the front end of the air chamber is provided in the portion corresponding to the nozzle throat portion where the pressure difference between the inner pressure of the drive unit mounting room and the rear lower side of the cooler becomes maximum. Since the exhaust port is provided, the hot air that has passed through the cooler is discharged to the second hot air by the large differential pressure between the nozzle throat part where a large negative pressure is generated and the internal pressure of the high-pressure drive unit mounting room. The cooling effect of the cooler can be enhanced by positively flowing out from the outlet to promote the introduction of air into the cooler.

Further, since the air chamber is bulged toward the drive unit mounting room side, and the upper wall is formed in a side wedge shape with the rearward slanting downward, the hot air flowing out from the second hot air discharge port is formed. Can be made to flow rearward along the slope of the upper wall of the air chamber to shorten the separation area of the underfloor flow due to the turbulent flow of hot air outflow behind the second hot air outlet, and the nozzle rear end portion The hot air exhaust efficiency can be improved without affecting the hot air exhaust action from the hot air exhaust port.

Further, since the hot air flowing out from the second hot air discharge port can be directed to the rearward and downward direction along the inclination of the upper wall of the air chamber, it is possible to prevent the hot air flowing out from the front of the vehicle when the vehicle is stopped. be able to.

A fifth aspect of the present invention is characterized in that an air spoiler portion projecting downward is formed at the lower edge of the second hot air discharge port of the fourth aspect.

According to the fifth aspect of the invention, the underfloor flow is further throttled downward by the air spoiler portion immediately before the second hot air discharge port to further increase the differential pressure with respect to the internal pressure of the drive unit mounting room. The amount of hot air discharged from the second hot air discharge port can be increased.

A sixth aspect of the present invention is characterized in that an attachment portion to the vehicle body is set on the upper wall of the air chamber according to the fourth and fifth aspects.

According to the sixth aspect of the present invention, the undercover can be attached to the vehicle body by effectively utilizing the bulging-molded air chamber in the drive unit mounting room, and the undercover can be attached to the vehicle body at the attachment portion of the upper wall of the air chamber. The structure of the cover can be simplified.

According to a seventh aspect of the present invention, the second hot air outlet of any one of the second to sixth aspects is obliquely downwardly inclined from the rear of the second hot air outlet to the edge of the hot air outlet at the rear end of the nozzle. It is characterized by forming an underfloor flow acceleration surface that accelerates the underfloor flow.

According to the structure of claim 7, the underfloor flow accelerating surface behind the second hot air discharge port rectifies the high-pressure hot air flowing out from the second hot air discharge port in a layered manner to form the underfloor flow. By eliminating the separation and accelerating the underfloor flow again, the pressure difference between the hot air discharge port at the rear end of the nozzle and the internal pressure of the drive unit mounting room is increased, and the hot air flow from the hot air discharge port at the rear end of the nozzle is increased. The discharge efficiency can be improved.

The eighth aspect of the present invention is characterized in that an air spoiler portion that projects downward is formed at the lower edge of the hot air discharge port that is the rear end edge of the underfloor flow acceleration surface according to the seventh aspect.

According to the structure of claim 8, immediately before the hot air exhaust port at the rear end of the nozzle, the underfloor flow is throttled downward by the air spoiler section to further increase the differential pressure from the room pressure inside the drive section, and Since the flow velocity of the flow is increased and the flow is made to flow backward, the region having a large differential pressure can be expanded backward and the hot air discharge efficiency from the hot air discharge port can be further improved.

In the ninth aspect, the formation position of the air spoiler portion at the lower edge of the hot air discharge port, which is the rear edge of the underfloor long-flow accelerating surface of the eighth aspect, is substantially the same as the front-rear axis in the front-rear direction. It is characterized by being set to.

According to the ninth aspect of the invention, since the air spoiler portion at the rear end of the underfloor flow acceleration surface where the ground clearance of the undercover is the lowest, is provided at substantially the same longitudinal position as the front wheel shaft. Even when riding on an obstacle such as a curb, it is possible to avoid road surface interference of the air spoiler and prevent damage to the under cover.

According to a tenth aspect of the present invention, an air spoiler portion projecting downward is formed at the lower edge of the hot air outlet of the first to ninth aspects, and the air spoiler portion is inclined rearward and upward from the lower edge of the air spoiler portion. It is characterized in that the barrier guide portion is formed by bending and an opening is formed in the barrier guide portion.

According to the structure of claim 10, claim 1
In addition to the effects of ~ 9, when the hot air exhaust port interferes with an obstacle such as a curb when the vehicle is retreating, the barrier guide portion comes into contact with this obstacle and the barrier guide portion follows the obstacle. By riding on, the hot air exhaust port is elastically deformed upward as a whole and damage to the under cover can be avoided.

Further, since the barrier guide portion is provided with the opening, the hot air discharging action from the hot air discharging port in the drive unit mounting room is not impaired.

According to an eleventh aspect of the present invention, there is formed a rectifying section that is inclined rearward and downward from the upper edge of the barrier guide section of the tenth aspect, and the lower edge ground height of the rectifying section is set above the air spoiler section. It is characterized in that the second barrier guide portion which is set higher than the height and which is inclined rearward and obliquely upward from the lower edge of the rectifying portion is formed by bending.

According to the structure of claim 11, claim 1
In addition to the effect of 0, the second barrier guide portion comes into contact with an obstacle when the vehicle moves backward, and the height of the obstacle that directly hits the barrier guide portion can be regulated, thereby obstructing the barrier guide portion and the air spoiler portion. It is possible to greatly limit the interference with the object and avoid deformation or breakage of the air spoiler portion as much as possible, thereby improving the quality and reliability.

Further, the high-pressure hot air flowing out from the opening of the barrier guide portion can be straightened by the straightening portion in a layered manner to eliminate the separation of the underfloor flow, and the hot air discharge efficiency from the hot air discharge port at the rear end of the nozzle can be improved. Can be improved.

According to a twelfth aspect, among the left and right hot air outlets according to the first to eleventh aspects, the opening area on the windward side in the rotation direction of the cooler fan disposed in the front part of the drive unit mounting room is set. It is characterized in that it is set smaller than the opening area on the leeward side in the rotation direction of the cooler fan.

According to the structure of claim 12, claim 1
In addition to the effects of 11 to 11, the hot air discharge amount can be made substantially equal on the windward side and the leeward side of the left and right hot air discharge ports in the cooler fan rotation direction. It is possible to prevent the axis of the underfloor flow that flows rearward from shifting in the left-right direction, and it is possible to further enhance the cooling effect of the heat generating portion in the central portion below the floor.

[0038]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes an undercover that closes the lower side of the drive unit mounting room. In this embodiment, the lower side of the engine room E / R in which the engine 11 is mounted as the drive unit mounting room is A range from the front end to the lower side of the oil pan 12 is closed by an under cover 1.

The undercover 1 is formed in a flat plate shape made of a resin material or a steel plate material, and the underfloor flow forming a nozzle 9 between the left and right sides of the undercover 1 from the front end toward the rear side. The constricted flow surface 2 is provided as a recess, and an underfloor flow converging portion 3 is formed in the central portion of the undercover 1 between these underfloor flow constricted surfaces 2 and 2.

The underfloor flow constricting surface 2 is formed by bending the front end portion thereof to form the nozzle throat portion 10 at the front end portion of the nozzle 9, and the underfloor flow constricting surface 2 of the undercover 1 is formed. Formed over the rear end, the rear end of the underfloor flow contracting surface 2 is opened to the rear end of the nozzle 9 to form a hot air discharge port 4 for letting out hot air in the engine rooms E and R.

In this embodiment, the undercover 1 joins the flat portion 5 at the front end thereof to the lower surface of the radiator core lower member 16 which is the strength member in the vehicle width direction at the front portion of the engine room E / R, and the underfloor flow converging portion. The mounting portions 6 formed on both sides of the rear end of the sub-frame 3 are coupled to the lower surface of the sub-frame (not shown).

Further, the flanges 7 on both the left and right edges of the under cover 1 are brought into contact with and engage with the outer surface of the front side member (not shown).

The oil pan 12 of the underfloor flow converging section 3
The portion located directly below is slightly recessed so that the oil pan 1
The air circulation portion 8 is formed between the bottom portion of the first and second bottom portions.

In FIG. 1, 13 is a transmission and 1
Reference numerals 4 and 15 denote an air conditioner condenser as a cooler and a radiator arranged at the front of the engine room E / R.

According to the structure of the above embodiment, the nozzles 9 are formed in the front-rear direction between the underfloor flow contraction surface 2 and the road surface G on both the left and right sides of the undercover 1, and the underfloor flow contraction surface 2 is formed. Since the nozzle throat portion 10 is formed below the front end portion of the, the underfloor flow that flows in from the front of the vehicle when the vehicle is traveling is throttled by the nozzle throat portion 10, and the left and right underfloor flow contraction surfaces 2 and 2 are The underfloor flow converges at the front part of the underfloor flow converging section 3 in the central part of the undercover 1 formed in the above, and the flow rate of the underfloor flow flowing backward along the underfloor flow converging section 3 at a high speed is Will be increased.

As a result, the underfloor flow is positively focused to the central portion on the lower floor side behind the underfloor flow converging unit 3, and the transmission 13 arranged in the central portion on the lower floor side is not shown. It is possible to enhance the cooling effect of the heat generating parts such as the propeller shaft and the rear differential.

Further, since the rear end of the underfloor flow constricting surface 2, that is, the rear end of the nozzle 9 is the hot air discharge port 4, the hot air is increased by the nozzle 9 and the hot air flows at a high speed. The negative pressure value generated in the vicinity of the exhaust port 4 becomes large, the high-pressure hot air in the engine room E / R is positively discharged from the hot-air exhaust port 4, and the high-pressure hot air in the engine room E / R is left and right. By flowing out from the hot air outlets 4 and 4, the high-pressure hot air becomes an air curtain to promote the converging action of the underfloor flow in the central portion under the floor, and more effectively cool the heat generating portion. Can be done.

Moreover, since the hot air in the engine rooms E and R is positively discharged from the hot air outlets 4 and 4, the air conditioner condenser 14 and the radiator 15 in the engine rooms E and R are discharged. Air can be positively introduced into the coolers to enhance the cooling effect of these coolers 14 and 15.

FIGS. 3 and 4 show a second embodiment of the present invention. In this embodiment, the underfloor flow contracting surfaces 2 and 2 of the first embodiment shown in FIGS. The curved shape of the front end portion is provided on the lower side of the rear portion of the radiator 5 with the nozzle throat portion 1
0 is formed, and a second hot air exhaust port 17 for letting out hot air in the engine rooms E and R is formed in a portion corresponding to the nozzle throat portion 10.

In this embodiment, the air spoiler portion 18 protruding downward is bent at the front edge of the second hot air outlets 17, 17.

According to the structure of the second embodiment, the second hot air exhaust port is provided in the portion corresponding to the nozzle throat portion 10 where the differential pressure between the engine 15 and the internal pressure of the engine room ER under the radiator 15 is maximum. Due to the provision of 17, the large differential pressure between the nozzle throat portion 10 and the high engine room E / R internal pressure, at which a large negative pressure is generated,
The hot air that has passed through the coolers such as the air conditioner condenser 14 and the radiator 15 can be positively caused to flow out from the second hot air exhaust port 17 to promote the introduction of air into the coolers 14 and 15, so that they can be cooled. The cooling effect of the vessels 14 and 15 can be further enhanced.

The left and right second hot air outlets 1 are also provided.
The high-pressure hot air flowing out from 7, 17 serves as an air curtain, and the action of focusing the underfloor flow can be promoted at the front end portion of the underfloor flow focusing section 3.

Therefore, the effect of converging the underfloor flow in the central portion on the lower floor side behind the under cover 1 is further enhanced, and the cooling effect of the heat generating portion can be further enhanced.

In particular, in this embodiment, since the air spoiler portion 18 protruding downward is bent at the front edges of the second hot air outlets 17, 17, the air spoiler portion 18 serves as the second air spoiler portion. Immediately before the hot air exhaust ports 17 and 17, the underfloor flow is further throttled downward to further increase the differential pressure between the nozzle throat portion 10 and the engine room E / R internal pressure, and from these second hot air exhaust ports 17 and 17. The amount of hot air discharged can be increased.

As a result, the cooling effect of the coolers such as the air conditioner condenser 14 and the radiator 15 is further enhanced, and
It is possible to further promote the converging action of the underfloor flow in the underfloor flow converging section 3.

FIGS. 5 and 6 show a third embodiment of the present invention. In this embodiment, the front ends of the underfloor flow constricting surfaces 2 and 2 of the first embodiment shown in FIGS. The curved portion of the nozzle throat portion 1
0 is formed, and this under-bed flow contracting surface 2,
In the portion corresponding to the nozzle throat portion 10 of No. 2, the front end is a second hot air exhaust port 17 that is bulged to the engine room E / R side to let out hot air in the engine room E / R, and the upper wall A side wedge-shaped air chamber 19 in which 19a is formed obliquely downward and rearward is provided.

In this embodiment, the second hot air outlet 1
The underfloor flow accelerating surface 20 inclined rearward and downward is formed from the rear of the nozzles 7 and 17 to the edges of the hot air outlets 4 and 4 at the rear end of the nozzle 9, and the underfloor flow accelerating surface 20 further causes the underfloor flow. I try to accelerate.

Further, in this embodiment, the underfloor flow accelerating surfaces 20, 2 forming the lower edges of the second hot air outlets 17, 17 and the edges of the hot air outlets 4, 4 at the rear end of the nozzle 9.
The air spoiler portions 18 and 21 projecting downward are respectively bent and formed at the rear end edges of the air chambers 0, and the flat attachment portions 19 are attached to the upper walls 19a and 19a of the air chambers 19 and 19, respectively.
b and 19b are formed, and the upper walls 19a and 19a of the air chambers 19 and 19 are effectively used to connect both side portions of the intermediate portion of the under cover 1 to the lower surface of the front side member (not shown) to enhance the mounting rigidity. I am allowed to do so.

Further, the air spoiler portion 21 provided at the edge of the hot air discharge port 4 at the rear end of the nozzle 9 is set at a position in the front-rear direction substantially the same as the axle W · O of the front wheel W.

In other words, the underfloor flow constricting surfaces 2 and 2 of the undercover 1 are formed to have a length such that their rear ends are located at substantially the same longitudinal position as the front wheel shaft W · O.

Therefore, according to the structure of the third embodiment, the nosle throat portion 10 in which the differential pressure of the radiator 15 and the internal pressure of the engine room E / R on the lower rear side are maximum.
Since the second hot air exhaust port 17 at the front end of the air chamber 19 is provided in the portion corresponding to the above, the nozzle throat portion 10 and the high pressure engine room E where a large negative pressure is generated.
The hot air that has passed through the coolers such as the air conditioner condenser 14 and the radiator 15 can be positively discharged from the second hot air outlet 17 due to the large pressure difference between the R internal pressure and the second embodiment. As well as these coolers 14, 1
The cooling effect can be remarkably enhanced by promoting the introduction of air into No. 5.

Further, since the air chamber 19 is bulged and formed on the engine room E / R side, and the upper wall 19a thereof is formed by sloping downwardly and obliquely downward to form a side wedge shape. The hot air flowing out from the hot air discharge port 17 is smoothly discharged rearward along the inclination of the air chamber upper wall 19a, and a separation region of the underfloor flow due to the turbulent flow of the hot air discharge is formed behind the second hot air discharge port 17. Can be short.

As a result, the hot air discharging action from the hot air discharging port 4 at the rear end of the nozzle 9 is not affected, and the hot air discharging efficiency can be improved as a whole, so that the cooler 1
Not only can the cooling effect of 4, 15 be enhanced, but the focusing action of the underfloor flow in the central portion under the floor by the air curtain of the hot air flowing out from these hot air outlets 17, 4 can be promoted.

Moreover, the hot air flowing out from the second hot air outlet 17 can be directed rearward and obliquely downward along the inclination of the air chamber upper wall 19a, so that the second hot air outlet 17 is stopped when the vehicle is stopped. Entrainment to the front of the vehicle that flows out from the vehicle can be suppressed, and the coolers 14, 15 when the vehicle is stopped
Does not impair the cooling effect of.

In particular, in this embodiment, the underfloor flow accelerating surface 2 inclined rearward and obliquely downward from the rear of the second hot air exhaust ports 17, 17 to the hot air exhaust ports 4, 4 at the rear end of the nozzle 9.
Since 0, 20 are formed, this underfloor flow acceleration surface 20
The high-pressure hot air flowing out from the second hot air exhaust port 17 is rectified in a layered manner to eliminate separation of the underfloor flow, and the underfloor flow is accelerated again, so that the hot air exhaust port 4 at the rear end of the nozzle 9 has an engine. By increasing the pressure difference between the room E and R inner pressures, the hot air discharge efficiency from the hot air discharge port 4 at the rear end of the nozzle 9 can be further improved.

In addition to the fact that the air spoiler portion 18 provided at the lower edge of the second hot air exhaust port 17 can increase the amount of hot air exhausted from the second hot air exhaust port 17 as in the second embodiment. Then, the underfloor flow is narrowed downward immediately before the hot air exhaust port 4 by the air spoiler portion 21 provided at the edge of the hot air exhaust port 4 at the rear end of the nozzle 9 in the engine room E.
・ The differential pressure from the R internal pressure is increased, and the flow velocity of the underfloor flow is increased to flow backward to expand the region having a large differential pressure backward, thereby further improving the hot air discharge efficiency from the hot air discharge port 4. Therefore, the cooling effect of the coolers 14 and 15 and the cooling effect of the heat generating portion by promoting the focusing of the underfloor flow in the central portion below the floor can be further enhanced.

Further, since the air spoiler portion 21 at the edge of the hot air exhaust port 4 where the ground clearance of the under cover 1 is the lowest, is provided in the front-rear direction position substantially the same as the front wheel axis W.O. Even when riding on an obstacle such as the above, the air spoiler portion 21 is displaced approximately in the vertical movement of the front wheel W to avoid road surface interference and prevent damage to the under cover 1.

FIG. 7 shows a fourth embodiment of the present invention. In this embodiment, the third embodiment shown in FIGS.
The barrier guide portion 23 inclined rearward and obliquely upward from the lower edge of the air spoiler portion 21 formed by projecting downward at the lower edge of the hot air outlets 4 and 4 which are the rear end edges of the underfloor flow acceleration surfaces 20 and 20 of the embodiment. An opening 2 through which the high-pressure hot air in the engine room E / R flows out to the barrier guide portion 23 by bending.
4 is formed.

Further, in this embodiment, the third hot air exhaust port 2 is provided between the second hot air exhaust port 17 and the underfloor flow acceleration surface 20.
5 are arranged in a row in the front-rear direction, and the third hot air outlet 2
The high-pressure hot air in the engine rooms E and R can also flow out from the No. 5 to improve the hot air discharge efficiency.

Therefore, according to the structure of this embodiment, in addition to the effects of the embodiment shown in FIGS. 5 and 6, the hot air exhaust ports 4 and 4 which have the lowest ground clearance when the vehicle retreats have obstacles such as curbs. When interfering with an object, the barrier guide portion 23 hits the obstacle in advance, and the barrier guide portion 23 obstructively rides up along the inclination of the obstacle, so that the hot air outlets 4, 4 are entirely raised. Elastically deformed to under cover 1
The damage of can be avoided.

The barrier guide portion 23 has an opening 2
Since the No. 4 is formed, the function of discharging hot air in the engine room E / R is not impaired even slightly.

FIGS. 8 and 9 show a fifth embodiment of the present invention. In this embodiment, the barrier guide portion 23 of the fourth embodiment shown in FIG. The rectifying portion 26 that is inclined is formed, and the ground height H ₂ of the rectifying portion 26 is set higher than the ground height H ₁ of the air spoiler portion 23, and the rectifying portion 26 is inclined rearward and upward from the lower edge of the rectifying portion 26. The inclined second barrier guide portion 27 is formed by bending.

Further, in this embodiment, among the hot air exhaust ports 4 and 4 on the left and right of the under cover 1, the hot air on the windward side in the rotation direction of the cooler fan 28 arranged in the front part of the engine room E / R. The opening area of the discharge port 4 is set to the cooling fan 2
It is set to be smaller than the opening area of the hot air exhaust port 4 on the leeward side in the rotation direction of No. 8.

For example, as shown in FIG. 9, when the cooler fan 28 rotates in the direction of arrow a, the opening width L ₁ of the hot air outlet 4R on the right side of the vehicle, which is on the windward side in the rotational direction, is set to the leeward side in the rotational direction. Is formed to have a width smaller than the opening width L ₂ of the hot air exhaust port 4L on the left side of the vehicle.
The opening area difference is set to L.

Therefore, according to the structure of this embodiment, in addition to the effect of the embodiment shown in FIG. 7, the second barrier guide portion 27 comes into contact with an obstacle in advance when the vehicle retreats, and the barrier guide portion 23. Since the height of an obstacle that directly hits can be regulated, the barrier guide portion 23 and the air spoiler portion 21
The air spoiler part 2
It is possible to avoid deformation or breakage of item 1 as much as possible, and to improve the quality and reliability.

Further, since the high-pressure hot air flowing out from the opening of the barrier guide portion 23 can be straightened by the straightening portion 26 to eliminate the separation of the underfloor flow, the hot air discharge ports 4 and 4 at the rear end of the nozzle 9 can be removed. The efficiency of discharging hot air can be improved.

Here, if the hot air discharge ports 4 and 4 have the same opening area, the hot air discharge port 4, which is on the windward side in the rotation direction of the cooler fan 28, has a large hot air discharge amount and is on the lee side in the rotation direction. Since the hot air exhaust port 4 tends to reduce the hot air exhaust amount, the left and right hot air exhaust ports 4,
The layer of the air curtain due to the high-pressure hot air flowing out of 4 becomes non-uniform on the left and right, and the underfloor flow flowing from the underfloor flow converging section 3 in the center of the undercover 1 toward the rear of the vehicle is directed toward the thin air curtain side It tends to be biased toward.

However, as in this embodiment, when the cooler fan 28 rotates in the direction of the arrow a, the opening area of the hot air exhaust port 4R on the right side of the vehicle, which is on the windward side in the rotational direction, is on the lee side in the rotational direction. By setting it smaller than the opening area of the left hot air outlet 4L, the hot air outlets from the left and right hot air outlets 4R, 4L can be made substantially equal, and the underfloor flow converging portion 3 can be rearward of the vehicle. It is possible to prevent the axis of the underfloor flow that flows toward the center from shifting in the left-right direction, and therefore, it is possible to further enhance the cooling effect of the heat generating portion in the center below the floor.

The air spoiler portion 21, the barrier guide portion 23, the opening 24, the rectifying portion 26 and the second barrier guide portion 27 are set, and the opening area difference is set between the left and right hot air discharge ports 4 and 4. It goes without saying that the same effect can be obtained by applying the embodiment shown in FIGS.

[0081]

As described above, according to the present invention, the following effects can be obtained.

According to the first aspect, the underfloor flow that flows into the lower side of the undercover from the front side of the vehicle when the vehicle is traveling is the nozzle throat portion of the front end portion of the nozzle formed by the underfloor flow contraction surface on both left and right sides. The underfloor flow is now concentrated at the front part of the underfloor flow converging part in the center of the undercover formed between these left and right underfloor flow constriction surfaces.
It is possible to increase the flow rate of the underfloor flow that flows rearward at high speed along the underfloor flow converging section.

As a result, the underfloor flow can be positively focused to the central portion on the lower floor side behind the underfloor flow converging portion, and the cooling effect of the heat generating portion arranged in the central portion on the lower floor side can be enhanced. .

Further, since the rear end of the nozzle is a hot air discharge port, the negative pressure value generated near the hot air discharge port becomes large due to the underfloor flow that flows at high speed at the nozzle and flows at a high speed, so that the drive unit is mounted. The high-pressure hot air in the room is positively discharged from the hot-air exhaust port, and the high-pressure hot air in the engine room flows out from the left and right hot-air exhaust ports. The converging action of the underfloor flow in the central portion of the side is promoted, and the cooling effect of the heat generating portion can be more effectively performed.

Moreover, since the hot air in the drive unit mounting room can be positively discharged from the hot air exhaust port in this manner, the air to the cooler arranged in the front portion of the drive unit mounting room can be discharged. The introduction can be positively performed to enhance the cooling effect of the cooler.

According to the second aspect, since the second hot air exhaust port is provided in the portion corresponding to the nozzle throat portion where the pressure difference between the inner pressure of the drive unit mounting room and the rear lower side of the cooler becomes maximum. Due to the large pressure difference between the nozzle throat where a large negative pressure is generated and the high pressure inside the drive unit mounting room, the hot air that has passed through the cooler is positively discharged from the second hot air outlet. Since the introduction of air into the cooler can be promoted, the cooling effect of the cooler can be further enhanced.

Further, the high-pressure hot air flowing out from the second hot-air outlet serves as an air curtain, and the front end portion of the under-floor flow converging portion can promote the converging action of the under-floor flow. The effect of focusing the underfloor flow in the lower central portion can be further enhanced, and the cooling effect of the heat generating portion can be further enhanced.

According to the third aspect of the present invention, the underfloor flow is further throttled downward by the air spoiler portion immediately before the second hot air outlet to further increase the differential pressure from the internal pressure of the drive unit mounting room.
Since the amount of hot air discharged from the second hot air discharge port can be increased, the cooling effect of the cooler can be further enhanced, and the converging action of the underfloor flow in the underfloor flow converging section can be further promoted, and the floor below It is possible to enhance the cooling effect of the heat generating portion in the central portion.

According to the fourth aspect, the second hot air discharge port at the front end of the air chamber is provided at the portion corresponding to the nozzle throat portion where the differential pressure from the inner pressure of the drive unit mounting room at the rear lower side of the cooler becomes maximum. Therefore, the hot air that has passed through the cooler is positively discharged from the second hot air outlet due to the large pressure difference between the nozzle throat part where a large negative pressure is generated and the room pressure inside the high-pressure drive unit. It is possible to enhance the cooling effect of the cooler by promoting the introduction of air into the cooler.

Further, since the air chamber is formed to be bulged toward the drive unit mounting room side, and the upper wall thereof is formed to have a side wedge shape which is formed to be inclined rearward and downward, from the second hot air discharge port. The hot air that has flowed out can smoothly flow rearward along the slope of the upper wall of the air chamber, and the separation area of the underfloor flow due to the turbulent flow of hot air can be shortened behind the second hot air outlet.

As a result, the hot air discharge action from the hot air discharge port at the rear end of the nozzle is not affected, and the hot air discharge efficiency can be improved as a whole, so that the cooling effect of the cooler can be enhanced. Of course, it is possible to enhance the effect of concentrating the underfloor flow in the central portion under the floor by the air curtains of the hot air flowing out from the front, rear, left and right hot air outlets, and enhance the cooling effect of the heat generating portion in the central portion under the floor. .

Moreover, since the hot air flowing out from the second hot air outlet can be directed rearward and obliquely downward along the inclination of the upper wall of the air chamber, it is possible to prevent the hot air flowing out toward the front of the vehicle when the vehicle is stopped. Therefore, the cooling effect of the cooler when the vehicle is stopped is not impaired.

According to the fifth aspect, the underfloor flow is further narrowed downward immediately before the second hot air outlet by the air spoiler section to further increase the differential pressure from the room pressure inside the drive unit,
The amount of hot air discharged from the second hot air discharge port can be increased, and the cooling effect of the cooler can be enhanced.

According to the sixth aspect, since the upper cover of the air chamber can be effectively used and the under cover can be attached to the vehicle body at the attaching portion of the upper wall, the structure of the under cover can be simplified and the cost can be reduced. Can contribute to down.

According to the seventh aspect, the underfloor flow accelerating surface behind the second hot air discharge port rectifies the high-pressure hot air flowing out from the second hot air discharge port in layers to eliminate separation of the underfloor flow. At the same time, by accelerating the underfloor flow again, the pressure difference between the hot air exhaust port at the rear end of the nozzle and the internal pressure of the drive unit mounting room is increased to improve the efficiency of hot air exhaust from the hot air exhaust port at the rear end of the nozzle. Can be improved.

According to the eighth aspect, immediately before the hot air discharge port at the rear end of the nozzle, the underfloor flow is throttled downward by the air spoiler section to further increase the differential pressure from the internal pressure of the drive unit mounting room.
And, since the flow velocity of the underfloor flow is increased and the air is circulated backward, the region having a large differential pressure can be expanded rearward to further improve the hot air discharge efficiency from the hot air discharge port, so that the cooling effect of the cooler can be obtained. Further, the effect of cooling the heat generating portion by promoting the focusing of the underfloor flow in the central portion on the lower side of the floor can be further enhanced.

According to the ninth aspect, since the air spoiler portion at the rear end of the underfloor flow accelerating surface where the ground clearance of the undercover is the lowest is set at substantially the same longitudinal position as the front wheel shaft,
Even when the front wheel rides on an obstacle such as a curb, the air spoiler portion is displaced approximately in the vertical movement of the front wheel to avoid road surface interference and prevent damage to the under cover.

According to the tenth aspect, in addition to the effects of the first to ninth aspects, when the hot air exhaust port interferes with an obstacle such as a curb when the vehicle is retreating, the barrier guide portion pre-contacts with the obstacle. Then, the barrier guide portion rides on the obstacle along the inclination thereof, whereby the hot air exhaust port is elastically deformed upward as a whole and the damage of the under cover can be avoided.

Further, since the barrier guide portion is provided with the opening, the hot air discharging action from the hot air discharging port in the drive unit mounting room is not slightly impaired.

According to the eleventh aspect, in addition to the effect of the tenth aspect, the height of the obstacle which directly hits the barrier guide portion when the second barrier guide portion hits the obstacle when the vehicle moves backward is regulated. Therefore, the interference between the barrier guide portion and the air spoiler portion and the obstacle can be largely limited, and the deformation or damage of the air spoiler portion can be avoided as much as possible, so that the quality and reliability can be improved.

Further, the high-pressure hot air flowing out from the opening of the barrier guide portion can be straightened by the straightening portion in a layered manner to eliminate the separation of the underfloor flow, and the hot air discharge efficiency from the hot air discharge port at the rear end of the nozzle can be improved. Can be improved.

According to the twelfth aspect, in addition to the effects of the first to eleventh aspects, the opening area of the hot air exhaust port on the windward side in the cooler fan rotational direction of the left and right hot air exhaust ports is set to the leeward direction in the cooler fan rotational direction. Since the opening area of the hot air exhaust port on the side can be set to be smaller, the high pressure hot air discharged from the left and right hot air exhaust ports in the drive unit mounting room can be made approximately equal, so the center of the under cover It is possible to prevent the axis of the underfloor flow flowing from the underfloor flow converging unit toward the rear of the vehicle from deviating in the left-right direction, and it is possible to further enhance the cooling effect of the heat generating unit in the center below the floor.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along the line AA of FIG. 2 showing a first embodiment of the present invention.

FIG. 2 is a perspective view of an under cover of the same embodiment.

FIG. 3 is a sectional view taken along line BB in FIG. 4 showing a second embodiment of the present invention.

FIG. 4 is a perspective view of the under cover of the same embodiment.

FIG. 5 is a sectional view taken along the line CC of FIG. 6 showing a third embodiment of the present invention.

FIG. 6 is a perspective view of the under cover of the same embodiment.

FIG. 7 is a sectional view showing a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a fifth embodiment of the present invention.

FIG. 9 is a perspective view of the same embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Undercover 2 Underfloor flow constricting surface 3 Underfloor flow converging part 4 Hot air discharge port 9 Nozzle 10 Nozzle throat part 14,15 Cooler 17 Second hot air discharge port 18,21 Air spoiler part 19 Air chamber 19a Upper wall 19b Mounting part 20 under-floor flow acceleration surface 23 barrier guide part 24 opening 26 rectifying part 27 second barrier guide part E / R drive unit mounting room G road surface W / O front wheel axle

Claims (12)

[Claims] 1. A lower side of a drive unit mounting room, which is separated from a front part of a vehicle body, is closed by a flat plate-like under cover, and the left and right side parts of the under cover are connected to a road surface from a front end portion to a rear side. In addition to forming a nozzle with a nozzle throat part at the front end part, the rear end is opened to form a hot air discharge port for discharging hot air in the drive unit mounting room. An underfloor structure for an automobile, characterized in that an underfloor flow converging portion is formed between a front end portion and a rear end of a central portion of an undercover between flow contraction surfaces. 2. The underfloor flow contraction surface is formed in a curved shape in which a nozzle throat part is formed below a rear part of a cooler arranged in a front part of a drive unit mounting room, and the underfloor flow contraction surface is formed. 2. The underfloor structure for an automobile according to claim 1, wherein a second hot air outlet for letting out hot air in the drive unit mounting room is provided in a portion of the flow surface corresponding to the nozzle throat portion. 3. The underfloor structure for an automobile according to claim 2, wherein an air spoiler portion projecting downward is formed at a front edge of the second hot air outlet. 4. The underfloor flow contraction is formed by forming a front end portion of the underfloor flow contraction surface into a curved shape in which a nozzle throat portion is formed below a cooler arranged in a front part of a drive unit mounting room. In the part corresponding to the nozzle throat part of the surface, the front end is formed as a second hot air discharge port that is bulged toward the drive unit mounting room side to let out hot air in the drive unit mounting room, and the upper wall is obliquely downward and rearward. The underfloor structure for an automobile according to claim 1, wherein a side wedge-shaped air chamber formed by tilting is provided on the underside. 5. The underfloor structure for an automobile according to claim 4, wherein an air spoiler portion protruding downward is formed at a lower edge of the second hot air outlet. 6. The underfloor structure for an automobile according to claim 4, wherein an attachment portion to the vehicle body is set on the upper wall of the air chamber. 7. An underfloor flow accelerating surface for accelerating the underfloor flow is formed by obliquely forming a slanting downward slant from the rear of the second hot air exhaust port to the edge of the hot air exhaust port at the rear end of the nozzle. The underfloor structure for an automobile according to any one of claims 2 to 6. 8. The underfloor structure for an automobile according to claim 7, wherein an air spoiler portion projecting downward is formed at the lower edge of the hot air outlet serving as the rear edge of the underfloor flow acceleration surface. 9. The formation position of the air spoiler portion at the lower edge of the hot air discharge port, which is the rear end edge of the underfloor flow acceleration surface, is set to the substantially same front-back direction position as the front wheel shaft. Underfloor structure for automobiles. 10. An air spoiler portion projecting downward is formed at the lower edge of the hot air outlet, and a barrier guide portion inclined rearward and obliquely upward from the lower edge of the air spoiler portion is formed by bending, and an opening is formed in the barrier guide portion. The underfloor structure for an automobile according to claim 1, wherein the underfloor structure is formed. 11. A straightening portion which is inclined rearward and downward from an upper edge of the barrier guide portion is formed, and a ground height of a lower edge of the straightening portion is set higher than a ground height of an air spoiler portion, and
11. The underfloor structure for an automobile according to claim 10, wherein a second barrier guide portion inclined rearward and obliquely upward from the lower edge of the rectifying portion is formed by bending. 12. The opening area on the windward side in the rotation direction of the cooler fan disposed in the front part of the drive unit mounting room among the left and right hot air outlets is larger than the opening area on the downwind side in the rotation direction of the cooler fan. A small value is set, and a small value is set.
The underfloor structure for an automobile according to any one of 1.