JP7090377B2 - Vehicle front structure - Google Patents

Description

The present invention relates to a vehicle front structure, and more particularly to a vehicle front structure having an undercover that constitutes the bottom surface of the vehicle and covers a part or all of the lower part of the engine.

Conventionally, an undercover that constitutes the bottom surface is provided in the front part of the vehicle, and by covering the vehicle components such as the engine from below with the undercover, the unevenness of the bottom surface of the vehicle is eliminated and the lower part of the vehicle body is covered when the vehicle is running. The resistance of the flowing air flow is reduced to improve the aerodynamic performance.

However, if the lower surface of the engine room is closed by the undercover, there is a problem that the heat generated from the engine, the exhaust pipe, or the like causes hot air to be trapped in the engine room and the temperature of peripheral parts to rise.

Patent Document 1 discloses a vehicle lower structure relating to an undercover as a structure for solving the problem of hot air in the engine room while improving aerodynamic performance. This vehicle lower structure has a first undercover that covers the engine room at the front of the vehicle from the lower side of the vehicle, and a second undercover provided on the rear side of the vehicle of the first undercover. An exhaust portion having an opening for communicating the engine room and the underfloor of the vehicle is provided between the undercover and the second undercover.

Japanese Unexamined Patent Publication No. 2015-545888

In the vehicle lower structure described in Patent Document 1, when traveling, an air flow can be flowed from the front to the rear of the vehicle along the lower surfaces of the first undercover and the second undercover to improve the aerodynamic performance and the exhaust portion. The hot air in the engine room can be exhausted from. As a result, it is possible to suppress the temperature rise of the engine peripheral parts as compared with the one having no exhaust unit.

However, since the opening of the exhaust section is blocked by the airflow rectified by the first undercover, there is a problem that the hot air in the engine room cannot be sufficiently discharged, and while ensuring the aerodynamic performance. There has been a demand for a structure that can discharge hot air more effectively.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle front structure capable of effectively discharging hot air in an engine room while suppressing deterioration of aerodynamic performance of the vehicle. ..

In order to achieve the above object , one embodiment of the present invention is a vehicle front structure including an undercover that constitutes the bottom surface of the vehicle and covers a part or all of the lower part of the engine, wherein the undercover is a structure. It has a first opening and a second opening arranged in the front-rear direction of the vehicle, and the first opening is located behind the radiator fan whose center of the opening is arranged in front of the engine in the front-rear direction of the vehicle. The length of the vehicle in the front-rear direction is smaller than that of the second opening, and the second opening is behind the first opening when the vehicle travels at a predetermined speed. In addition, it is arranged within the range of the negative pressure region formed by separating the airflow flowing from the front to the rear of the vehicle by the air discharged from the first opening , and the heat generating portion in the engine room in the front-rear direction of the vehicle. It is characterized in that it is located at the same position as or behind it.

According to this configuration, the air introduced into the engine room through the radiator fan can be discharged to the lower surface side of the undercover from the first opening of the undercover. The airflow discharged from the first opening separates the airflow flowing along the underside of the undercover during travel, resulting in a lower side of the second opening located behind the first opening. A negative pressure region is formed by peeling. As a result, the amount of air discharged to the outside of the undercover from the second opening can be increased, and the hot air that has passed through the heat generating portion in the engine room is at the same position as the heat generating portion or behind it in the front-rear direction of the vehicle. It is possible to sufficiently discharge from the second opening located in.

Further, in one embodiment of the present invention, in the vehicle front structure, a lid portion that can open and close the first opening, a detecting means for detecting the temperature of a predetermined object in the engine room, and the detection means. A control unit that opens the lid when the temperature detected by the means is equal to or higher than a predetermined temperature and closes the lid when the temperature is lower than the predetermined temperature is provided , and the second opening is always open. It is characterized by being.

According to this configuration, when the temperature of a predetermined object in the engine room is lower than the predetermined temperature and the temperature rise of the engine peripheral parts is suppressed, the first opening is closed to form an undercover. It is possible to eliminate the separation of the airflow flowing under the floor of the vehicle along the vehicle and improve the aerodynamic performance of the vehicle. Further, when the temperature of a predetermined object in the engine room is higher than the predetermined temperature and the hot air in the engine room needs to be discharged, the first opening is opened and the second opening is used. It is possible to increase the amount of discharged air and prevent the accumulation of hot air in the engine room.

Further, one embodiment of the present invention is characterized in that, in the vehicle front structure, the lid portion moves open to the engine room side or slides open along the surface of the undercover. do.

According to this configuration, it is possible to prevent the airflow flowing under the floor of the vehicle from being disturbed by the lid portion in the open state, so that the aerodynamic performance can be maintained.

Further, in one embodiment of the present invention, in the vehicle front structure, both ends of the second opening are within the range sandwiched between both ends of the first opening in the vehicle width direction in the vehicle width direction. It is characterized by being located.

According to this configuration, the entire area of the second opening can be positioned within the negative pressure region of the first opening, and the efficiency of discharging hot air from the second opening can be improved.

According to the vehicle front structure according to the present invention, it is possible to prevent the accumulation of hot air in the engine room while maintaining the aerodynamic performance of the vehicle.

The cross-sectional view of the front part of a vehicle which shows the structure of the front part of a vehicle which is 1st Embodiment of this invention. Bottom view of the front of the vehicle. The same bottom view as FIG. 2 which shows the modification of the 2nd opening. The bottom view which shows the modification of the 1st opening and the 2nd opening. The cross-sectional view which shows the main part of the vehicle front structure which is the 2nd Embodiment of this invention. The configuration explanatory view of the control mechanism of the vehicle front structure of 2nd Embodiment. The flowchart which shows the control procedure by a control part. Sectional drawing of the main part of the vehicle front structure which shows the deformation example of a lid part. FIG. 1 is a cross-sectional view similar to FIG. 1 for explaining a conventional undercover.

(First Embodiment)
FIG. 1 is a cross-sectional view of the vehicle front portion in the vehicle width direction center portion showing the vehicle front structure according to the first embodiment of the present invention, and FIG. 2 is a bottom view of the vehicle front portion. The vehicle front structure 10 according to the present invention is applied to a vehicle such as an automobile.

As shown in FIG. 2, an engine room 11 in which an engine EG is mounted is provided in the front portion of the vehicle body of the vehicle. The upper part of the engine room 11 is closed by a panel-shaped front hood 12 that can be opened and closed, a radiator unit 20 is arranged in the front part of the engine room 11, and a heat exchanger of an air conditioner is placed in front of the radiator unit 20. The constituent capacitors 24 are arranged. An undercover 30 that covers a part or all of the engine EG and forms the bottom surface of the vehicle is arranged in the lower part of the engine room 11. Further, behind the engine room 11, a cabin is provided via a toe board (not shown).

The radiator unit 20 includes a radiator 21 and a radiator fan 22 arranged behind the radiator 21. The radiator 21 dissipates heat from the cooling water for the engine that circulates in the engine EG, and the radiator fan 22 creates an air flow by rotation and can positively take in the outside air into the engine room.

The radiator unit 20 and the condenser 24 are fixed to the radiator panel 28 attached to the vehicle body. Both sides of the radiator panel 28 in the vehicle width direction are arranged at both ends in the vehicle width direction of the vehicle body and are fixed to a pair of front side frames (not shown) extending in the vehicle front-rear direction.

A front grill 14 and a bumper face 16 are provided at the front end of the vehicle (that is, in front of the condenser 24 and the radiator unit 20).

The front grill 14 is an exterior member arranged between the hood 12 and the bumper face 16 in the vertical direction, and has a grill opening 15 for introducing air into the engine room 11.

The bumper face 16 is an exterior member provided at the front end portion of the vehicle body, is made of a resin material such as PP, and includes a bumper main body portion 17 and an air dam portion 18 located below the bumper main body portion 17. .. The bumper main body portion 17 and the air dam portion 18 are each formed of a plate-shaped member extending in the vehicle width direction, and have a substantially U-shaped vertical cross section in which the rear side of the vehicle is open. Further, an outside air introduction port 19 is formed between the bumper main body portion 17 and the air dam portion 18.

The undercover 30 is a plate-shaped member that forms the bottom surface of the vehicle, and has a function of protecting the bottom surface of a power unit such as an engine EG arranged in the engine room 11 and rectifying the traveling wind passing through the lower part of the vehicle. .. The front end of the undercover 30 is fixed to the bottom rear end of the bumper face 16, and both sides of the rear part of the undercover 30 in the vehicle width direction are fixed to an engine mount cross member or the like (not shown). In the present embodiment, as shown in FIG. 2, the undercover 30 extends from the front end of the vehicle to the positions of the left and right front wheels 45 and 46.

The undercover 30 has a first opening 32 and a second opening 34 that communicate the engine room 11 with the outside of the vehicle. The openings 32 and 34 are formed side by side in the front-rear direction of the vehicle, and the second opening 34 is located behind the first opening 32 of the vehicle.

The first opening 32 is a discharge port for discharging the air introduced into the engine room 11 through the radiator fan 22 to the outside of the undercover 30, and the opening center 32a is the radiator fan 22 in the front-rear direction of the vehicle. It is located behind.

The second opening 34 is formed so that a part of the opening is located at the same position as or behind the heat generating portion in the engine room 11 in the vehicle front-rear direction. Here, the heat generating portion is a portion where the temperature becomes high as the engine EG is driven, and in the present embodiment, the exhaust pipe 40 is described as the heat generating portion as an example. It is preferable that the opening center 34a of the second opening 34 in the vehicle front-rear direction is located at the same position as or behind the heat generating portion, and in the present embodiment, the opening front end 34b of the second opening 34. Overlaps the exhaust pipe 40, and the center 34a of the opening is located behind the exhaust pipe 40.

The first opening 32 is formed at a position close to the second opening 34 in the vehicle front-rear direction. Specifically, when the vehicle travels at a predetermined speed, the air discharged from the first opening 32 causes an air flow flowing from the front to the rear of the vehicle along the underfloor of the vehicle (that is, the lower surface of the undercover 30). The second opening 34 is formed so as to be located within the range of the negative pressure region NP formed by peeling. In the example shown in FIG. 2, the openings 32, 34 are formed in a substantially rectangular shape, but the shapes of the openings 32, 34 are not limited to this, and an elliptical shape, another polygonal shape, or the like is appropriately set. It is possible to do.

In the present embodiment, the width W1 of the first opening 32 in the vehicle front-rear direction is set smaller than the width W2 of the second opening 34 in the vehicle front-rear direction. Further, the first opening 32 and the second opening 34 are set so that the positions of the left and right ends in the vehicle width direction are substantially the same, and the lengths L1 and L2 in the vehicle width direction are substantially the same.

Next, the operation and effect of the first embodiment will be described.

In the vehicle provided with the vehicle front structure 10 described above, as shown in FIG. 1, the air introduced into the vehicle through the grill opening 15 and the outside air introduction port 19 is indicated by the arrow of the dot in FIG. It is diffused into the engine room 11 by the radiator fan 22, and a part of the diffused air is discharged to the outside of the vehicle through the first opening 32. The airflow flowing from the front to the rear of the vehicle along the lower surface 30a of the undercover 30 during traveling is separated from the lower surface 30a by the air discharged from the first opening 32, and the airflow flowing to the undercover 30 and the rear of the vehicle A negative pressure region NP (region surrounded by a broken line in FIG. 1) is formed between them. By forming this negative pressure region NP on the lower side of the second opening 43, the air in the engine room 11 is positively discharged from the second opening 34 to the outside of the undercover 30. As a result, as shown by the filled arrow in FIG. 1, the air that has passed through the exhaust pipe 40 and has become hot is sufficiently discharged to the outside of the vehicle from the second opening 34, and the hot air in the engine room 11 is prevented from being trapped. can do. The second opening 34 may be at least partially in the negative pressure region NP by the first opening 32, but as in the present embodiment, the second opening 34 is the second opening in the vehicle width direction. By locating both ends of the first opening 34 within the range sandwiched between both ends in the vehicle width direction of the first opening 34, almost the entire area of the second opening 34 can be within the negative pressure region NP.

9 (a) and 9 (b) are diagrams illustrating a conventional vehicle front structure, respectively. When the undercover 130 does not have an opening like the vehicle front structure 100 shown in FIG. 9A, the hot air in the engine room 11 is not discharged but is trapped inside, and the temperature of the peripheral parts rises. It will rise. Further, when the undercover 230 is provided with the opening 234 only in the vicinity of the heat generating portion in the front-rear direction of the vehicle as in the vehicle front structure 200 shown in FIG. 9B, hot air is discharged from the opening 234. However, when the vehicle is running, the opening 234 is blocked by the airflow flowing under the floor of the vehicle, and the hot air in the engine room 11 cannot be sufficiently discharged. In particular, when the vehicle travels at high speed, the airflow flowing under the floor becomes an air curtain and the opening 234 is closed, and hot air is trapped in the engine room 11.

On the other hand, in the vehicle front structure 10 of the present embodiment, as described above, the negative pressure region P is formed under the vehicle floor by the first opening 32 when the vehicle is running, so that the second opening 34 It is possible to promote the discharge of hot air from the engine room 11 and prevent the hot air from being trapped in the engine room 11.

(Modification 1)
FIG. 3 is a bottom view similar to FIG. 2 showing a modified example of the second opening 34. In the second opening 34 of this modification, the length L2 in the vehicle width direction is shorter than the length L1 of the first opening 32, and both ends 34b, 34c of the second opening 34 in the vehicle width direction. Is located inside both ends 32b and 32c of the first opening 32. In this modification, the entire area of the second opening 34 is ensured to enter the negative pressure region NP by the first opening 32 shown by the dots in FIG. 7, and the hot air is discharged from the second opening. Efficiency can be increased.

(Modification 2)
FIG. 4 is a bottom view similar to FIG. 2 showing another modification of the first opening 32 and the second opening 34. In this modification, the first opening 32 and the second opening 34 are each composed of a plurality of openings arranged in the vehicle width direction. In the illustrated example, each of the openings is composed of three openings, but the number of openings is not limited to this. The plurality of openings 34-1, 34-2, 34-3 constituting the second opening 34 are provided corresponding to the positions of the exhaust pipe 40 and other heat generating portions in the engine room 11, and each opening is provided. A plurality of openings 32-1, 32-2, 32-3 constituting the first opening 32 are provided so that the portions 34-1, 34-2, 34-3 are located in the negative pressure region NP. Be done. In this modification, the range of the negative pressure region NP can be reduced to improve the aerodynamic performance, and the predetermined heat generating portion can be effectively cooled. In addition, only one of the first opening 32 and the second opening 34 may be configured by a plurality of openings.

(Second embodiment)
Next, the vehicle front structure 60 of the second embodiment of the present invention will be described with reference to FIGS. 5 to 7. In each figure, the same elements as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the vehicle front structure 10 of the present embodiment, the undercover 30 includes a lid portion 50 capable of opening and closing the first opening 32. Further, the vehicle front structure 10 includes an actuator 52 that drives the lid portion 50 to move in the open direction or the closed direction, and a temperature sensor (detection means) 54 that detects the temperature of a predetermined object in the engine room 11. The ECU (electronic control unit) 56, which is a control unit, is provided. In FIG. 5, the description of the actuator 52, the temperature sensor 54, and the ECU 56 is omitted.

The lid portion 50 has a flat plate shape having a shape and a size capable of closing the first opening 32, and is formed in a substantially rectangular shape in the present embodiment, and the edge portion of the first opening 32 is formed. One side portion of the lid portion 50 is attached to the shaft member 51 provided in the above, and is configured to be rotatable around the shaft member 51. Further, the lid portion 50 has a closed position in which the first opening 32 is closed by the driving force of the actuator 52 and an open position in which the lid portion 50 rotates toward the engine room 11 to open the first opening 32. It is configured to be movable between. In FIG. 5, the closed position of the lid portion 50 is shown by a virtual line, and the open position is shown by a solid line.

In order to directly or indirectly detect whether or not hot air is trapped in the engine room 11, the temperature sensor 54 directly or indirectly detects the temperature of a predetermined object in the engine room 11, for example, the internal temperature of the engine room 11. It detects the temperature of the cooling water for an engine, the temperature of an arbitrary component in the engine room 11, and the like. The temperature sensor 54 of the present embodiment is arranged in the engine room 11 and detects the internal temperature of the engine room 11.

The ECU 50 includes, for example, information processing means such as a CPU, storage means such as RAM and ROM, an input / output interface, and the like. The ECU 50 is connected to the actuator 52 and the temperature sensor 54, can identify the open / closed state of the lid 50 based on the detection signal from the actuator 52 and the instruction signal to the actuator 52, and is based on the detection result of the temperature sensor 54. Then, the actuator 52 is operated to move the lid portion 50 to the open position or the closed position.

A predetermined temperature threshold value that serves as a reference for opening / closing control of the lid portion 50 is set in the ECU 50. In the present embodiment, the first temperature T _close , which is a threshold for switching the closed lid 50 to the closed state, and the second temperature _Topen , which is the threshold for switching the closed lid 50 to the closed state, are present. It is set. Further, the first temperature T _close is set to a temperature higher than the second temperature _Topen .

Next, with reference to the flowchart of FIG. 7, the opening / closing operation of the first opening 32 by the ECU 50 of the vehicle front structure 10 will be described.

First, the ECU 50 determines whether the first opening 32 is in the open state or the closed state based on the detection signal from the actuator 52 (step S11).

When the first opening 32 is in the open state (step S11: Yes), the ECU 50 determines whether or not the temperature T in the engine room 11 is less than the first temperature T _close based on the detection result of the temperature sensor 54. Is determined (step S12).

When the detected temperature T is less than the first temperature T _close (step S12: Yes), the actuator 52 is operated to move the lid 50 to the closed position to close the first opening 32 (step S13). , Returns the control process.

When the temperature T is equal to or higher than the first temperature T _close in step S12 (step S12: No), the process returns to step S11, and the subsequent processes are sequentially executed.

On the other hand, in step S11, when the first opening 32 is in the closed state (step S11: No), the ECU 50 sets the temperature T in the engine room 11 to the second temperature _Topen based on the detection result of the temperature sensor 54. It is determined whether or not it is the above (step S14).

When the detected temperature T is equal to or higher than the second temperature _Topen (step S14: Yes), the actuator 52 is operated to move the lid portion 50 to the open position to open the first opening 32 (step S15). , Returns the control process.

When the temperature T is _lower than the second temperature Top in step S14 (step S14: No), the process returns to step S11, and the subsequent processes are sequentially executed.

The above-mentioned control is performed regardless of whether the vehicle is running or stopped. Instead, the first opening 32 is opened when the vehicle is stopped, and the opening / closing control shown in FIG. 7 is performed when the vehicle is running. May be good.

In the vehicle front structure 10 described above, when the first opening 32 is in the open position and the temperature T of the engine room 11 detected by the temperature sensor 54 is less than the predetermined first temperature T _close , that is, the engine room. When the temperature T in the 11 is relatively low and the temperature rise of the engine peripheral parts is suppressed, the first opening 32 is closed to separate the airflow flowing under the vehicle floor along the undercover 30 during traveling. It can be eliminated and the aerodynamic performance of the vehicle can be improved.

Further, when the first opening 32 is in the open position and the temperature T of the engine room 11 detected by the temperature sensor 54 is equal to or higher than the predetermined first temperature T _close , that is, the temperature T in the engine room 11 is compared. When the temperature of the engine peripheral parts is high and there is a concern that the temperature of the engine peripheral parts rises, it is possible to maintain the open state of the first opening 32 to promote exhaust from the second opening 34 and prevent the accumulation of hot air. ..

Further, when the first opening 32 is in the closed position and the temperature T of the engine room 11 detected by the temperature sensor 54 is less than the predetermined second temperature _Topen , that is, the temperature rise of the engine peripheral parts is suppressed. In this case, the closed state of the first opening 32 can be maintained to enhance the aerodynamic performance of the vehicle.

Further, when the first opening 32 is in the closed position and the temperature T of the engine room 11 detected by the temperature sensor 54 is equal to or higher than the predetermined second temperature _Topen , that is, there is a concern that the temperature of the engine peripheral parts may rise. In this case, the first opening 32 can be opened to promote exhaust from the second opening 34, the cooling effect of the exhaust pipe 40 can be enhanced, and the accumulation of hot air can be prevented.

By maintaining the open state without providing the lid portion in the second opening 34, the hot air in the engine room 11 can always be discharged from the second opening 34, and the engine peripheral parts are appropriate. It is designed to be cooled to the engine.

(Modification 3)
FIG. 8 is a cross-sectional view of a main part showing a modified example of the lid portion 50. The lid portion 50 of this modification slides and moves along the surface of the undercover 30 by the driving force of the actuator 52 to open or close the first opening 32. In the illustrated example, a structure that slides in the vehicle front-rear direction along the upper surface of the undercover 30 is shown, but a configuration that slides along the lower surface of the undercover 30 or a configuration that slides in the vehicle width direction is used. You may. By making the lid portion 50 slide and move along the surface of the undercover 30 in this way, the airflow in the engine room 11 and the airflow flowing under the vehicle floor are obstructed by the lid portion 50. Can be suppressed.

The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the spirit of the invention. For example, the lid portion 50 shown in the second embodiment or the modification 3 may be provided for the first opening 32 shown in the modification 1 or the modification 2. When the first opening 32 is composed of a plurality of openings 32-1, 32-2, 32-3 as in the second modification, each opening 32-1, 32-2, 32-3 The lid portion 50 may be provided, or all the openings 32-1, 32-2, 32-3 may be closed by one lid portion 50.

10 Vehicle front structure 11 Engine room 14 Front bumper 16 Upper outside air inlet 18 Lower outside air inlet 20 Radiator unit 21 Radiator 22 Radiator fan 30 Undercover 32 First opening 34 Second opening 40 Exhaust pipe (heat generating part) )
50 Closure 54 Temperature sensor (detection means)
56 ECU (control unit)
EG engine NP negative pressure region

Claims (4)

A vehicle front structure with an undercover that constitutes the bottom of the vehicle and covers part or all of the lower part of the engine.
The undercover has a first opening and a second opening arranged in the front-rear direction of the vehicle.
The first opening is formed so that the center of the opening is located behind the radiator fan arranged in front of the engine in the vehicle front-rear direction and the length in the vehicle front-rear direction is smaller than that of the second opening.
The second opening is behind the first opening , and when the vehicle travels at a predetermined speed, the air discharged from the first opening causes the air discharged from the front to the rear of the vehicle. The vehicle front structure is arranged within the range of the negative pressure region formed by separating the flowing airflow , and is located at the same position as or behind the heat generating portion in the engine room in the vehicle front-rear direction. .. A lid that can open and close the first opening,
A detection means that detects the temperature of a predetermined object in the engine room,
A control unit that opens the lid when the temperature detected by the detection means is equal to or higher than a predetermined temperature and closes the lid when the temperature is lower than the predetermined temperature.
Equipped with
The vehicle front structure according to claim 1, wherein the second opening is always open . The vehicle front structure according to claim 2, wherein the lid portion opens and moves toward the engine room side, or slides and opens and moves along the surface of the undercover. One of claims 1 to 3, wherein both ends of the second opening are located within a range sandwiched between both ends of the first opening in the vehicle width direction in the vehicle width direction. The vehicle front structure described in.

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