JP3338832B2 - Ventilation duct - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ventilation system mounted on an automobile to secure a ventilation volume in a vehicle interior during traveling and to prevent foreign matter, exhaust gas and the like from entering a vehicle interior when the vehicle is stopped. Related to ducts.

[0002]

2. Description of the Related Art At the rear of a vehicle body, there is a ventilation duct for replacing the air in a passenger compartment during traveling. The relatively narrow cabin is easily polluted by human breathing, cigarette smoke, etc., so fresh air is taken in from the front of the cabin, and a ventilation duct is used to discharge air contaminated by tobacco smoke etc. in the cabin. The air is discharged to the outside through the vehicle to allow ventilation inside the vehicle. FIG. 6 shows an example of a conventional ventilation duct. In FIG.
Is a frame having an outlet 13 formed therein. The frame 1 is provided with a flap 2 so as to be swingable, so that the outlet 13 can be closed by the weight of the flap 2 from the outside of the vehicle. While the automobile is running, the flap 2 changes its opening degree due to the pressure difference between the inside and outside of the vehicle interior, so that ventilation is performed. On the other hand, such a flap 2 is used when the vehicle is stopped or the like.
To prevent foreign matter (dust, dust, etc.) from entering the vehicle interior from the outside. Furthermore, when the air pressure in the vehicle interior becomes lower than the external air pressure, such as when a window is opened during traveling, the flap 2 comes into close contact with the exhaust port 13 due to the pressure difference, and exhaust gas enters the vehicle. It also functions as a check valve to prevent Therefore, it is desirable that the flap 2 opens and closes sensitively even if the pressure difference between the inside and outside of the vehicle is small. Such ventilation ducts can be used on the back of automobile bumpers, doors,
Attached to one of the rear pillars.

[0003]

Under these circumstances, when the ventilation duct is attached to the rear side of the bumper, the exhaust port is opened due to negative pressure in the passenger compartment during driving, running of puddles, and further, washing the vehicle. There is a problem that water enters the vehicle from the thirteen. Therefore, a curved tubular water return 3 having a height equal to or higher than the flooded height is provided on the rear casing side of the frame body 1 to prevent water from entering the passenger compartment. In particular, depending on the type of vehicle, the permissible height of flooding is determined to be equal to or higher than a certain value. However, when the water return 3 is provided, a turbulence state is generated by changing the flow direction of the air, so that the ventilation resistance increases (pressure loss increases) and the ventilation efficiency deteriorates. FIG. 7 shows the difference in ventilation efficiency between a ventilation duct with a water return and a ventilation duct without a water return. The figure, above the projected area S = 57.6cm ² opening area used (horizontal projected area) ventilation duct of M = 109.0cm ^2, the inlet 31 to the outlet 13, water flashing height b = 130 mm, and the projected area in the discharge port direction A =
This is a measurement of a change in ventilation efficiency with respect to the air volume when a water return 3 of 70 cm ² is provided. As can be seen from the graph, the provision of the water return has conventionally caused a significant reduction in ventilation efficiency. Therefore, while faced with the trade-off problem of keeping the ventilation efficiency while preventing water from entering, as a result, the ventilation duct becomes unnecessarily large and the structure of the flap 2 is changed. And struggled to deal with it.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a ventilation duct which sufficiently exhibits a water return effect while maintaining a high ventilation efficiency, and which does not become unnecessarily large. Aim.

[0005]

In order to achieve the above object, a ventilation duct according to the present invention comprises a frame having a discharge port for discharging air inside the vehicle to the outside of the vehicle, and a discharge port formed outside the frame on the outside of the vehicle. And a plate-shaped flap that opens only in the direction of the outside of the vehicle due to the pressure difference between the inside and outside of the vehicle, and an inlet at the upper end that is provided to surround the back of the outlet on the vehicle side of the frame. Characterized in that the projected area above the inflow port is set to be at least twice as large as the projected area in the discharge port direction. here,
The “projection area of the drainage port direction” refers to the actual opening area of the drainage port when the water return height is beyond the discharge port of the frame. When it is low, it refers to the projected area of the return of water.

[0006]

When the projected area above the inlet of the water return is less than twice the projected area in the direction of the outlet of the water return as in the past, the ventilation wind is bent sharply near the inlet, and Due to the turbulence generated by the change of the flow direction, the ventilation resistance increases, and the required ventilation efficiency cannot be obtained. On the contrary,
When the upper projected area of the water return inlet is set to twice or more than the projected area of the water return outlet direction as in the present invention, the air flow direction is not suddenly bent in the water return. However, even if water is returned, the ventilation efficiency does not decrease so much.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. (1) Configuration of Ventilation Duct FIG. 1 is an overall perspective view of a ventilation duct according to the present invention, FIG.
FIG. In the figure, reference numeral 1 designates an inclined wall 11 and a horizontal wall 15 connected at upper and lower two places of a vertical wall 12 in a vertical cross-sectional shape of "∠".
Shows a frame formed by opening a frame. Here, the inclined wall 11 is about 6
It is formed at an inclination angle of 0 degrees, and the width of each inclined wall 11 is 60 m.
m, an outlet 13 having a height of 50 mm is formed. Code 14
Are mounting holes for mounting on the vehicle body at four corners of the frame 1. The frame 1 is formed of a polypropylene resin.

Reference numeral 2 denotes an outlet 1 made of a flexible ethylene-propylene-diene copolymer rubber (JIS hardness: 50 degrees).
3 shows a flap formed in a square plate shape one size larger than 3; By fixing the upper side of the flap 2 to the upper edge of each inclined wall 11 by heat fusion or a screw 5 or the like, the flap 2 is slidably mounted on the vehicle outside the outlet 13. still,
The flap 2 is mounted by providing a mounting hole near the upper edge of the inclined wall 11, integrally forming a hook-shaped mounting piece on the upper side of the flap 2, and inserting the mounting piece into the mounting hole. Can be swingably suspended. Then
When the vehicle interior pressure becomes higher than the vehicle outside pressure, for example, when the vehicle is running, the flap 2 is separated from the discharge port 13 and the discharge port 13 is opened even if the pressure difference is relatively small. The flap 2 normally closes the outlet 13 by its own weight, and furthermore, when the air pressure in the vehicle interior becomes lower than the air pressure outside the vehicle,
The exhaust gas contacts the exhaust port 13 to prevent the exhaust gas from flowing into the vehicle. In order to prevent the flap 2 from unnecessarily opening the discharge port 13 due to vibration during traveling, a ferromagnetic material such as ferrite is blended in the constituent material of the flap 2 and the inclined wall 11 and adhered by its magnetic force. It is also good to increase the holding power. In addition, a filler such as metal powder may be mixed into the material of the flap to increase the weight so as to prevent the delusion.

Reference numeral 3 denotes a curved water return formed integrally with the frame 1. The water return 3 is formed so as to surround the discharge port 13 on the rear compartment side of the frame body 1, bends backward with a gentle curved surface, and extends vertically upward. The water return 3 has an inlet 31 at its upper end for taking in vehicle interior air. Here, assuming that the projected area in the outlet direction of the drainage 3 at the drainage height b is A and the projected area above the inlet 31 is S, in the present invention, this water is set such that the relational expression of S ≧ 2A is satisfied. The ventilation efficiency is improved by setting the depth L of the return 3.

(2) Performance Test In order to examine the effects of the projected area A of the water return 3 toward the outlet and the projected area S above the inflow port 31 on the ventilation efficiency E of the ventilation duct according to the present invention, The results of FIGS. 3 and 4 were obtained by performing a simple ventilation efficiency test. Ventilation efficiency test In the test according to FIG. 3, the depth L of the water return inflow port was set to 70 in the ventilation duct D having the discharge port 13 of the above shape and size.
mm, the ratio of the above-mentioned projected area S in the upward direction and the projected area A in the discharge port direction was varied, and the relationship between S / A and ventilation efficiency E was measured. FIG.
In the test according to the above, a ventilation duct D having a high water return height b was formed at various water return inlet depths L, the water return was cut off little by little, and the ventilation efficiency at each height point was examined.

FIG. 5 shows a test apparatus. The device is a partition 4
1 to form box bodies 42 and 43 partitioned by
Tube 45 on the outer wall, fan 44 on the partition wall 41, box 43
Attach a test ventilation duct D to the outer wall of the test. And
A nozzle 451 is provided in the tube 45, and the nozzle 451 and the manometer 46 are connected by a tube 47, so that the tube 45
To measure the static pressure P ₂ inside the container 43
Also, a nozzle 411 is provided, and a ventilation resistance (P ₁ −P ₀ ) in the box 43 can be measured by a manometer 49 connected via a tube 48.

Using the above apparatus, the following ventilation resistance was measured. First, a ventilation duct D having a predetermined water return height b is installed, and the fan 44 is rotated to blow air into the box 43 from the outside (one suction port of the cylindrical tube 45). Ventilation is performed so that the air of the air is discharged from the ventilation duct D. Then, the static pressure P _{2 is} calculated by the manometer 46.
And measure the ventilation volume from the conversion table (Bellmouth pressure vs. air volume). On the other hand, the ventilation resistance (P ₁ −P ₀ ) is
9 from the measurements.

Here, the ventilation efficiency E in FIG. 3 is obtained by the following equation. E [%] = {F ₀ / F} × 100 Here, F ₀ is calculated by the following equation. F ₀ = ｛(ρ / 2) × (1 / 0.36) ² / (P ₁ −
P ₀ )｝ ^1/2 × Va Here, Va is a ventilation amount [m ³ / h]. Also, ρ =
1.293 / {(1 + 0.00367t) × 9.8}. The above t indicates a temperature [° C.]. On the other hand, the above F adopts the horizontal projected area (actual opening area) of the two discharge ports 13 in the ventilation duct D.

Test Results From the graph of FIG. 3 created in this manner, the ventilation efficiency E that can be achieved is less than 45% when the upper projected area S of the water return inlet is not more than twice the projected area A in the outlet direction. Although it does not exist, the ventilation efficiency E can be increased by more than twice.
It was confirmed that it could be increased to 5%. According to the Bellmouth effect, the shape around the inflow port 31 draws a gentle curve, so that it is considered that the ventilation resistance is reduced and the ventilation efficiency is favorably affected. By the way, when the S / A is 2 or more, the ventilation efficiency E is almost flat as can be seen from the graph, so that even if the size of the inflow port 31 is made larger, the ventilation efficiency is greatly improved. You can decide not to. Then, from the viewpoint of construction of the ventilation duct D and securing of installation space, the upper limit is determined to be S / A = 5. Thus, 2 ≦ S / A ≦
By selecting 5, the inlet 31 becomes larger than necessary,
The optimum dimension of the ventilation duct can be secured without increasing the dimension of the depth L and requiring extra mounting space on the back side of the bumper or the like. Further, the results of various experiments using the depth L of the inlet 31 as a parameter are shown in FIG. In FIG. 4, a symbol a indicates a height related to the projected area A in the discharge port direction. In each case, it was found that the ventilation efficiency E converged when the S / A became 2 or more, and a value close to the upper limit value was obtained. In FIG. 4, when the depth L is multiplied by the width of the water return 3, the upper projected area S is obtained. However, when the value of the depth L is large (that is, when the upper projected area S is large), the water return height b is high. It was confirmed that S / A = 2 or more at an early stage, and that the ventilation efficiency E quickly approached the upper limit.

It should be noted that the present invention is not limited to those shown in the above-described embodiments, and that various modifications can be made without departing from the scope of the present invention in accordance with the purpose and application. For example, the size, shape, material, and the like of the frame 1, flap 2, water return 3, and discharge port 13 are not limited to the present embodiment and can be changed according to the purpose and the like.

[0016]

As described above, the ventilation duct of the present invention can be mounted while maintaining a high ventilation efficiency while satisfying the water return function, without being unnecessarily large. It has an excellent effect on ensuring comfort.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a ventilation duct according to an embodiment.

FIG. 2 is a longitudinal sectional view of the ventilation duct of FIG.

FIG. 3 is a graph showing a change in ventilation efficiency according to a form of water return.

FIG. 4 is a graph showing a change in ventilation efficiency with respect to a water return height.

FIG. 5 is a perspective view showing a ventilation efficiency test apparatus.

FIG. 6 is a longitudinal sectional view of a conventional ventilation duct.

FIG. 7 is a graph showing a change in ventilation efficiency due to attaching a water return.

[Explanation of Signs] 1 Frame 13 Outlet 2 Flap 3 Water return 31 Inlet D Air ventilation duct S Projection area above the inflow port A Projection area in the outlet direction of the water return

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60H 1/26 611 B60H 1/26 B60H 1/26 671 B60H 1/26 681 B60H 1/26 641 F24F 13/14

Claims (1)

(57) [Claims] 1. A frame (1) having a discharge port for discharging air inside the vehicle to the outside of the vehicle, and a frame provided outside the vehicle outside the frame to close the discharge port. A plate-like flap (2) that opens only in the direction, and a curved tubular water return (3) that is provided to surround the back surface of the discharge port on the vehicle compartment side of the frame and has an inlet at the upper end. A ventilation duct, wherein the projected area above the inlet of the water return is set to be at least twice as large as the projected area in the direction of the outlet of the water return.