JPH07246900A - Air bag door structure for automobile - Google Patents

Abstract

PURPOSE:To obtain a product which is thin and whose appearance is not impaired, by forming a rupture part from a recessed groove part formed in the vicinity of a hollow brittle part formed along the rupture line of a car room member. CONSTITUTION:On the reverse surface side of an air bag door 10, a thin rupture part 13 consisting of a hollow brittle part 14 and a recessed groove part 15 is formed. The rupture part 13 is ruptured is preference when the air bag 10 is applied with the expansion pressure of an air bag 47 from the reverse surface, and the door part 11 is opened speedily and surely, and is formed along the rupture line of a car room side member 40. The stream of the high pressure gas G which is poured into the groove part 36 on the mold surface is controlled to the direction of the resin having the high fluidity, and transferred toward the air bag door inside direction. A projection part 17 is formed toward the inner surface direction of the door part 11 to the sectional surface shape of the space part of the hollow brittle part 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an automobile air bag door.

[0002]

2. Description of the Related Art In order to safely protect an occupant in a vehicle from an impact at the time of a collision, an airbag device is provided, for example, in a front passenger compartment member (instrument panel) on the passenger side. An example thereof is shown in FIG. In the figure, reference numeral 40 is a vehicle interior side member, and 41 is an airbag device. An opening 42 for the airbag device 41 is provided at a predetermined position of the vehicle-cabin-side member 40, and the opening 42 is provided in a normal state.
Is covered by an airbag door 43 having the same type of appearance as the passenger compartment member 40.

As shown in the figure, the airbag door 43 is made of a synthetic resin injection-molded product or the like, and the shape of a door portion 45 is defined by a cleaving portion 44 provided on the back surface side. Reference numeral 46 is a resin hinge integrally provided at one end of the airbag door 43. The tearing portion 44 is formed thinly by providing a concave groove portion having a V-shaped cross section from the back side of the airbag door. When the vehicle receives a large impact due to a collision or the like, the airbag 47 of the airbag device 41 is inflated. Then, the opening portion 44 is broken by the pressure, the door portion 45 of the airbag door 43 is opened, and the airbag 47 is deployed in the vehicle compartment.

In the air bag door having such a structure,
If the thickness of the thin open part increases, it may cause serious problems such as delay of the door deployment speed and breakage of parts other than the open part.
It is usually set to a degree.

In order to reduce the thickness of the thin-walled cleavage portion, it is necessary to increase the size of the protruding mold portion of the molding die that defines the concave groove portion. However, when the protruding portion of the molding die is enlarged, the fluidity of the molten resin material is hindered by the protruding portion, which causes a problem that molding defects are likely to occur. In order to solve this problem, conventionally, the filling pressure of the resin material into the molding die cavity has been increased, or the number of gates has been increased. There is a dislike that the cost of equipment must be increased because the capacity of the machine must be increased. Further, if the number of gates is increased, not only the number of steps for processing the gate portion is increased, but also the appearance of the product is impaired depending on the position of the gate.

[0006]

Therefore, the present invention is
The present invention has been proposed in view of such problems, and provides a novel structure of an airbag door having a thin-walled cleavage portion.

[0007]

That is, the present invention is
In an airbag door structure configured such that a cleaving portion provided in a vehicle compartment side member is broken by an inflation pressure when an airbag is deployed to open a door portion, the cleaving portion is a cleaving of the vehicle compartment side member. The structure of an automobile airbag door is characterized by comprising a hollow fragile portion formed along a line and a concave groove portion formed in the vicinity of the hollow fragile portion.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. 1 is a cross-sectional view showing the structure of an airbag door according to an embodiment of the present invention, FIG. 2 is a perspective view of the airbag door seen from the back side, and FIG. 3 is an end view taken along line 3-3 thereof. 4 to 6 are views showing the operation of the airbag, FIG. 4 is a sectional view showing an airbag door structure in a normal state, FIG. 5 is a sectional view showing a state where the airbag is inflated, and FIG. FIG. 9 is a cross-sectional view showing a state in which the airbag thus opened opens the airbag door. 7 is a sectional view showing another example of the structure of the present invention, and FIG. 8 is a sectional view showing the other example.

Further, FIGS. 9 to 11 show an example of the manufacturing method of the present invention. 9 is a cross-sectional view showing a molten resin material filled state in a molding die, FIG. 10 is a cross-sectional view showing a high-pressure gas injection state in the molding die, and FIG. 11 shows a state in which a protrusion is formed in a hollow fragile portion. FIG.

As shown in FIG. 1, the structure of the present invention has the airbag door 1 of the vehicle interior side member 40 as shown in FIG.
It is set to 0. The airbag door 10 is attached to the airbag device 41 provided on the back side of the vehicle interior side member 40 via the hinge portion 12 and covers the opening 42 thereof. The door portion 11 can be opened promptly and reliably.

The airbag door 10 is made of a synthetic resin injection molded product, and has a hinge portion 12 integrally formed at one end as shown in FIGS. 2 and 3. As a resin material forming the airbag door, an elastomer such as a thermoplastic polyolefin-based elastomer, a thermoplastic polyester-based elastomer, a thermoplastic polystyrene-based elastomer, a polycarbonate and an ABS resin or P
An alloy material with BT resin or the like is preferably used.

On the back side of the airbag door 10, there is provided a thin-walled cleavage portion 13 consisting of a hollow fragile portion 14 and a concave groove portion 15. When the airbag door 10 receives the inflation pressure of the airbag 47 from the back side, the tearing portion 13 preferentially breaks so that the door portion 11 can be opened quickly and surely. It is formed along the tear line of the side member 40.

As is well understood from FIG. 2, the hollow fragile portion 14 is provided in the ridge portion 16 projecting to the back surface of the airbag door 10 along the tear line. As shown in FIG. 3, the hollow fragile portion 14 shown here is formed such that the cross-sectional shape of the space portion thereof is a substantially long hole shape having a protrusion 17 in the inner surface side direction of the door portion 11. As a result, the thin portion due to the hollow fragile portion 14 becomes the door portion 1.
1 is formed widely in the vicinity of the surface of 1, and the strength of that portion is lower than that of other general portions of the door portion, so that the breaking of the cleaving portion 13 and the opening of the door portion 11 are more reliable.

The concave groove portion 15 is provided near the hollow fragile portion 14. The recessed groove portion 15 is provided from the back surface side of the door portion 11 along the tear line, and by making the portion of the door portion 11 thin so that its strength is lower than that of other general door portions. This is for facilitating the opening of the door portion 11 along the break line when the airbag door 10 is deployed. Since the hollow groove portion 15 is formed in a thin shape in which the tear line is fragile by the hollow fragile portion 14, the groove depth is formed to be shallower than that of the tear portion 44 of the conventional airbag door shown and described in FIG. However, the tear line is surely broken and the door 11 is opened promptly.

4 and 6 illustrate the operation of the structure of the present invention. In the drawings, the same reference numerals as those in FIGS. 1 to 3 denote the same members. As shown in FIG. 4, a door portion 11 defined by a tear line is provided at a predetermined position of the vehicle interior member 40. In the normal state, the airbag door portion 11 is attached to the upper portion of the airbag housing portion 48 of the airbag device 41 mounted on the back side of the vehicle interior side member 40 and covers the opening 42 thereof.

When the vehicle receives a large impact due to a collision or the like, as can be understood from FIGS. 5 and 6, the airbag 47 of the airbag device 41 is inflated, and the pressure thereof causes the airbag door portion 11 to be inflated. Is pushed up from the back side. Then, the thin tear portion 13 formed by the hollow fragile portion 14 and the concave groove portion 15 is broken, the airbag door portion 11 is quickly opened along the breaking line, and the airbag 47 is surely deployed in the vehicle compartment. You can

Further, the airbag door molded article having such a constitution may be used as a base material or an intermediate layer, and the surface thereof may be covered with a skin made of a soft synthetic resin sheet material or the like. An example thereof is shown in FIGS. FIG. 7 shows an example in which the entire surface of the airbag door 20 is covered with a skin 21 made of a soft synthetic resin sheet material or the like. Reference numeral 22
Is a cleavage portion, 23 is a hollow fragile portion, and 24 is a concave groove portion. Further, FIG. 8 is an example in which the entire front and back surfaces of the airbag door 29 are integrally covered with a skin 25 made of a soft synthetic resin sheet material or the like. Reference numeral 26 is a cleavage portion, 27 is a hollow fragile portion, 28
Is a groove.

9 to 11 show a method of manufacturing the airbag door structure shown in FIGS. 2 and 3. As a method for manufacturing the airbag door having the structure of the present invention, known injection molding is preferable, and includes a step of forming a concave groove portion and a step of forming a hollow fragile portion. In the figure, reference numeral 30 is an injection mold, 31 is a core mold, and 32 is a cavity mold.

First, the step of forming the concave groove portion will be described. As shown in FIG. 9, the air bag door molding die 30 is composed of a core die 31 and a cavity die 32. The die surface 33 of the core die 31 has a convex portion 34 along the tear line of the air bag door portion. Is provided. This convex portion 34 is shown in FIG.
The airbag door 10 shown in FIG.
This is for forming the concave groove portion 15 constituting the. Reference numeral 35 in the drawing represents a gate portion.

A groove 3 is formed on the mold surface outside the convex portion 34.
6 is provided. The groove portion 36 is for forming the ridge portion 16 for the hollow fragile portion 14, and
It is provided along with 4.

On the other hand, the cavity mold 32 has a core mold 31.
The heater 37 is provided inside the position corresponding to the convex portion of the. The heater 37 is for heating the mold portion on the inner surface side of the groove 36 to keep the resin material filled in that portion in the cavity mold in a molten state longer than other portions. In this embodiment, the temperature of the heater 37 is set to about 40-100 ° C. It is preferably 80 ° C. or higher. Thereby, the fluidity of the molten resin material on the inner surface of the groove 36 is kept high, and the flow direction of the high-pressure gas G injected into the mold in the next step is controlled.

That is, as shown in FIG. 9, the molten resin material P injected from the gate portion 35 is filled in a predetermined amount into the mold through the groove portion 36 having a larger cross-sectional area than other general portions and easily flowing. To be done. As described above, according to the structure of the present invention, since the concave groove portion 15 can be formed shallower than the conventional one, the convex portion 34 does not impede the fluidity of the molten resin material in the mold. Absent.

After the predetermined amount of the molten resin material P is filled in the mold from the gate portion 35 or before the completion of the molding, the high pressure gas G is injected from the gate portion 35 to form a hollow portion. The formation of the hollow portion by injecting such a gas is known as so-called gas injection molding.
An inert gas such as nitrogen is preferably used as the high-pressure gas G, and the pressure and the flow rate are appropriately set according to the type of the resin material P and the viscosity thereof.

The portion of the molded product corresponding to the groove portion 36 of the molding die 30 filled with the resin material P is formed thicker than other general portions, and therefore, the portion is filled. The molten resin has a molten state that lasts longer than other general parts. Therefore, as shown in FIG. 10, the high-pressure gas G injected from the gate portion 35 has a groove portion 36 having a high fluidity in a molten state.
It circulates in the resin P inside and a hollow portion is formed in the groove portion 36 portion.

Further, in this embodiment, the cavity mold 3 is used.
2 is provided with a heater 37 for heating the mold portion on the inner surface side of the groove portion 36, the molten resin P1 filled in the portion is more fluid than the molten resin material P2 outside the groove portion 36. Is high. Therefore, as understood from FIG. 11, the flow of the high-pressure gas G injected into the groove portion 36 is controlled toward the resin having high fluidity, and moves toward the inside of the airbag door. Then, a protrusion 17 toward the inner surface of the door 11 is formed in the cross-sectional shape of the space portion of the hollow fragile portion 14.

[0026]

As shown and described above, according to the present invention, since the cleaving portion is thinly formed by the hollow fragile portion and the concave groove portion, the conventional structure in which the cleaving portion is constituted only by the concave groove portion is provided. Even if the concave groove portion is formed shallower than the above, opening of the door portion is reliable and safe. Therefore, it is sufficient for the convex portion for the concave groove portion formed on the molding die surface to be high enough not to impede the fluidity of the molten resin, and an efficient and highly accurate product can be obtained. Further, unlike the prior art, it is not necessary to increase the filling pressure of the molten resin or increase the number of gates of the molding die, which is extremely economical and advantageous in terms of equipment and processes.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of an airbag door according to an embodiment of the present invention.

FIG. 2 is a perspective view of the airbag door as viewed from the back side.

FIG. 3 is an end view taken along line 3-3.

FIG. 4 is a cross-sectional view showing an airbag door structure in a normal state.

FIG. 5 is a cross-sectional view showing a state where the airbag is inflated.

FIG. 6 is a cross-sectional view showing a state in which an inflated airbag opens an airbag door.

FIG. 7 is a sectional view showing another example of the structure of the present invention.

FIG. 8 is a cross-sectional view showing another example of the same.

FIG. 9 is a cross-sectional view showing a filled state of a molten resin material in a molding die.

FIG. 10 is a sectional view showing a state of injecting high-pressure gas into the mold as well.

FIG. 11 is a cross-sectional view showing a state in which a protrusion is formed on a hollow fragile portion.

FIG. 12 is a cross-sectional view showing a general airbag door structure.

[Explanation of symbols]

 40 Vehicle side member 10 Airbag door 11 Door part 12 Hinge part 13 Cleavage part 14 Hollow fragile part 15 Recessed groove part 17 Projection part

Claims (2)

[Claims] 1. An airbag door structure configured such that a cleaving portion provided in a vehicle compartment side member is ruptured by an inflation pressure when an airbag is deployed to open a door portion, wherein the cleaving portion is the vehicle. A structure of an airbag door for an automobile, comprising a hollow fragile portion formed along a tear line of the chamber side member and a concave groove portion formed in the vicinity of the hollow fragile portion. 2. The hollow fragile portion according to claim 1, wherein the hollow fragile portion is formed in a ridge portion formed along a tear line, and a shape of a space portion thereof has a protrusion portion toward an inner surface of the door portion, and the concave portion is formed. A structure of an airbag door for an automobile, in which a groove is formed below the space projection.