AU731598B2 - Instrument panel for air bag - Google Patents

Description

IjU/Ul11 2&i/1 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: I. Invention Title: INSTSRUMENT PANEL FOR AIR BAG The following statement is a full description of this invention, including the best method of performing it known to us 1~1 INSTRUMENT PANEL FOR AIR BAG BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to an instrument panel for incorporating at inner side thereof an air bag in a folded state particularly for a front seat passenger among air bags for an automobile, which is broken to open such that the air bag is extended in front of a passenger by expansion of the air bag at emergency.

Description of Prior Art: Generally, as shown by Fig. 15 and Fig. 16, according to an instrument panel for an air bag of this kind, a foaming material of polyurethane or the like is injected and foamed between a skin member 52 having a break-open portion 51 with an H-like shape in plane view at a portion thereof in correspondence with an expanded portion of the air bag, and a door member 53 opposed to the inner side of the skin member 52 thereby integrating the skin member 52, the door member 53 and a foamed layer 54.

Conventionally, according to such an instrument panel, Sethe break-open portion 51 of the skin member 52 is consti- S tuted by a recess groove 51a formed on the rear face of the 2 skin member 52 and a projected portion 55 having a projection height which is equal to or substantially equal to a recess depth of the recess groove 51a, is projected from an edge portion side of the door member 53 toward the recess groove 51a. Further, when the door mamber 53 is pushed to open in an arrow mark direction of Fig. 16 by expansion of an air bag (not illustrated), the projected portion 55 on the side of the door member 53 applies impact on a vicinity of the break-open portion 51 in the skin member 52 to break the recess groove 51a constituting the break-open portion 51 by which a total of the break-open portion 51 is broken to open and the expanded air bag is extended in front of the instrument panel.

e According to such a conventional constitution, a thickness of the foaming layer 54 between the skin member 52 and the door member 53 opposed to the skin member 52, is constituted in a thickness which is uniform or substantially uniform over the entire region including the portion of forming the break-open portion 51.

Accordingly, particularly when the total wall thickness oo of the foaming layer 54 is large, the trajectory of motion of the projected portion 55 on the side of the door member 53 which is pushed to open by expansion of the air bag, is liable to be positionally shifted in respect of the break- 3 open portion 51 of the skin member 52. When such a positional shift is caused, unnecessary shear force is exerted on the foaming layer 54, foamed resin constituting the foaming layer 54 is liable to break in pieces and many broken pieces are liable to scatter. Further, the break force does not concentrate along the break-open portion 51 of the skin member 52 and is liable to deviate in the side direction of the break-open portion 51 or the like and as a result, it is difficult to achieve predetermined break-open function along the break-open portion 51.

Meanwhile, when the total wall thickness of the foaming layer 54 is reduced, although the break-open function is improved, the rigidity of the instrument panel becomes insufficient. Further, in forming the foaming layer 54 by injecting and foaming a foaming material between the skin *r a member 52 and the door member 53, it is difficult to fill and foam the foaming material uniformly over the entire region of the space and a problem is posed in respect of moldability of the total of the instrument panel.

SUMMARY OF THE INVENTION The present invention has been carried out in view of the above-described actual situation and it is an object of the present invention to provide an instrument panel for an 4 air bag capable of significantly improving break-open function in expanding the air bag while sufficiently ensuring rigidity and maintaining excellency in moldability.

In order to achieve the above-described object, according to a first aspect of the present invention, there is provided an instrument panel for an air bag constituted by injecting and foaming a foaming material between a skin member having a break-open portion at a location thereof in correspondence with an expanded portion of the air bag and a door member opposed to the skin member thereby integrating the skin member, the door member and the foaming layer, wherein a projected portion is projected from a portion of the door member opposed to the break-open portion of the skin member and a thickness between the projected portion and the break-open portion of the skin member is set to be small relative to a thickness of other portion.

According to the first aspect of the present invention, the thickness between the break-open portion of the skin member and the projected portion projected from the portion of the door member opposed to the break-open portion is set to be smaller relative to the thickness of other portion and therefore, the rigidity of the total of the instrument panel can be promoted by increasing the wall thickness of the total of the foaming layer and the moldability of the in- *ee 5 strument panel can be maintained excellently by injecting and filling the foaming material uniformly over the entire region of a space between the skin member and the door member regardless of the presence of the projected portion at the portion of the door member. At the same time, the positional shift between the trajectory of motion of the projected portion at the portion of the door member which is pushed to open in accordance with the expansion of the air bag and the break-open portion on the side of the skin member, can be dispensed with or can be made very small.

Accordingly, broken pieces of foamed resin of urethane or the like forming the foaming layer can be restrained from scattering as less as possible in expanding the air bag and further, the break-open function and the extension function of the air bag can be promoted by concentrating break force S. :i accompanied by expansion of the air bag at the break-open portion of the skin member via the projected portion on the side of the door member.

According to a second aspect of the present invention, as means for forming a local portion for reducing the thickness between the skin member and the door member, there is provided means wherein the break-open portion of the skin .e member is constituted by a relief groove projecting to a rear face side and a recess groove formed on the rear face ••eo 6 side of a bottom portion of the relief groove and a thickness between the bottom portion of the relief groove and the projected portion of the portion of the door member opposed to the bottom portion is set to be smaller than the thickness of the other portion.

Further, according a third aspect of the present invention, there is provided.means wherein the break-open portion of the skin member is a recess groove on a rear face side and a thickness between a bottom portion of the recess groove and the projected portion of the portion of the door member opposed to the bottom portion is set to be smaller than the thickness of the other portion.

Particularly, in the case of the means for forming the break-open portion from the relief groove projected to the rear face side of the skin member by constituting a devia- S. tion in a jig or a mold thickness as in the former aspect, S thermal expansion force or thermal contraction force of an instrument panel caused by termperature rise accompanied by irradiation of solar ray or the like or temperature drop accompanied by vehicular air conditioning or the like can be absorbed by the relief groove portion for constituting the break-open portion. That is, the relief groove portion can be operated as a thermal deformation absorbing portion for absorbing thermal deformation of the skin member e 7 by which heat reisistance of the skin member can be promoted. Further, design feature can also be promoted in view of outlook.

Further, in respect of the above-described constitution, according to a fourth aspect of the present invention, the projected portion of the portion of the door member which is pushed to open in accordance with expansion of the air bag is constituted by bonding opening ends of the door member projected toward a side of the skin member, or, according to a fifth aspect of the present invention, the projected portion of the portion of the door member which is pushed to open in accordance with expansion of the air bag is constituted by a recess portion projected integrally with the door member toward a side of the skin member and a top portion of the recess portion is formed in a thin wall.

:Particularly, in the case of the projected portion where the recess portion is formed to project integrally with the door member and the top portion is formed in a thin wall as in the latter aspect, thermal expansion force or thermal contraction force of an instrument panel caused by temperature rise accompanied by irradiation of solar ray or the like or temperature drop accompanied by vehicular air conditioning or the like, can be absorbed by bending the thin wall top portion of the recess portion constituting the 8 projected portion. That is, the projected portion can be operated as thermal deformation absorbing portion for absorbing thermal deformation of the door member.

In respect of the above-described constitution, according to a sixth aspect of the present invention, a wall thickness of a portion of the skin member opposed to substantially an entire region of a surface of the door member is preferably set to be thicker than a wall thickness at a surrounding portion. By constituting the wall thickness of the skin member in the region of arranging the door member thicker than the wall thickness of the surrounding in this way, the wall thickness of the break-open portion of the skin member can easily be ensured and the break-open function and the extension function of the break-open portion can be promoted while maintaining high uniformity of the break-open position of the skin member.

Further, in respect of the above-described constitu- *tion, according to a seventh aspect of the present invention, it is preferable that a thickness between the breakopen portion of the skin member and the projected portion of the portion of the door member opposed to the break-open portion is set to be 3/4 through 1/3 of a thickness therebetween at other portion. When the thickness between the break-open portion and the projected portion is set to a oeooo 9 thickness exceeding 3/4 of the thickness of other portion, in the case where the wall thickness of the foaming layer is increased for ensuring the rigidity of the total of the instrument panel, the trajectory of motion of the projected portion on the side of the door member that is pushed to open in accordance with expansion of the air bag is liable to be positionally shifted and the effect of improving the break-open function in expanding the air bag is lowered.

Further, when the thickness is set to be less than 1/3 of the thickness of the other portion, the foaming material is difficult to reach the entire region of the space by riding over the projected portion on the side of the door member where the local thichness reducing portion is formed and the moldability of the total of the instrument panel is deteriorated.

.oo.

:Further, in respect of the shape of the break-open portion of the skin member, according to an eighth aspect of *the present invention, the break-open portion of the skin member is formed in an H-like shape in a plane view constituted by a linear horizontal break-open portion and vertical break-open portions respectively connected orthogonally to S. both end portions of the horizontal break-open portion in a longitudinal direction, or a substantially double Y-like shape in a plane view constituted by a linear horizontal

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9 C~o 10 break-open portion and vertical break-open portions respectively connected to the horizontal break-open portion by being divided and expanded in a V-like shape from both end portions of the horizontal break-open portion in the longitudinal direction, or in an I-like shape in a plane view constituted only by a linear horizontal break-open portion, and a thickness between at least the linear horizontal break-open portion in the break-open portion of each of the plane view shapes and the projected portion of the portion of the door member opposed to the linear horizontal breakopen portion is set to be small relative to a thickness of other portion. In this way, the break-open function in expanding the air bag can be promoted regardless of the shape of the break-open portion of the skin member.

In this case, according to a ninth aspect of the present invention, it is preferable that a projection height of the projected portion of the door member opposed to a central portion of the horizontal break-open portion of the skin member is set to be higher than projection heights on both sides thereof. Thereby, the break-open portion of the skin member can be broken to open from the central portion and the function of extending the air bag can further be promoted.

According to a tenth aspect of the present invention, 0eo 11 there is provided an instrument panel for an air bag constituted by injecting and foaming a foaming material between a skin member having a break-open portion at a location thereof in correspondence with an expanded portion of the air bag and a door member having a break-open portion at a location in correspondence with the expanded portion of the air bag and arranged at a position on a side of the air bag opposedly to the skin member thereby integrating the skin member, the door member and the foaming layer wherein the break-open portion on a side of the skin member is formed in an I-like shape in a plane view comprising only a linear horizontal break-open portion, and wherein the break-open portion on a side of the door member comprises a linear horizontal breakopen portion positioned to overlap the horizontal break-open portion on the side of the skin member except both end portions in a longitudinal direction of the horizontal break-open portion and vertical break-open portions respectively connected to both end portions in the longitudinal direction of the horizontal break-open portion.

According to the tenth aspect of the present invention, in such a constitution, the break-open portion on the side 8 of the skin member is formed in the simple I-like shape in a plane view comprising only the linear horizontal break-open portion and therefore, even when the instrument panel per se o*o 12 is provided with a complicated three-dimensional shape, the constitution of a break-open portion fabricating jig or a molding die for providing the skin member with thickness deviation is simplified, design and fabrication is facilitated and the reduction in cost can be achieved. Further, the break-open portion of the skin member can be formed at a proper position with no shift while enhancing the degree of freedom of design in respect of the instrument panel per se.

Thereby, troublesome adjustment of modification of positional shift or the like is not needed and the fabrication efficiency of the break-open portion of the skin member can be promoted. Moreover, by concentratingly exerting the break force accompanied by the break-open of the break-open portion on the side of the door member having the vertical break-open portion to both end portions in the longitudinal .i direction of the break-open portion on the side of the skin C e S member which does not coincide with the break-open portion on the side of the door member, the break-open function substantially equivalent to that of the break-open portion provided also with vertical break-open portions can be achieved even with the simple I-like shape comprising only the horizontal break-open portion. Accordingly, when the air bag is expanded, a portion of the skin member and broken pieces of foamed resin constituting the foaming layer can ooeoo 13 be prevented from scattering and further, the break-open function and the extending function of the air bag can be promoted.

In this case, according to an eleventh aspect of the present invention, in respect of the break-open portion on the side of the door member, the break-open portion on the side of the door member is formed in either of an H-like shape in a plane view comprising the linear horizontal break-open portion and vertical break-open portions respectively connected orthogonally to both end portions in the longitudinal direction of the horizontal break-open portion, a substantially double Y-like shape in a plane view comprising the linear horizontal break-open portion and vertical break-open portions connected to the horizontal break-open portion by being respectively divided and expanded from the S. both end portions in the longitudinal direction of the horizontal break-open portion in a V-like shape and a substantially double channel shape in a plane view comprising the linear horizontal break-open portion and vertical breakopen portions in a channel-like shape connected to the both end portions in the longitudinal direction of the horizontal break-open portion.

Further, according to a twelfth aspect of the prevent invention, in respect of the break-open portion on the side 14 of the skin member, the break-open portion on the side of the skin member comprises either of a recess groove formed on a side of a rear face of the skin member and a thin wall portion formed by thinning a wall thickness on the side of the rear face of the skin member. Or, according to a thirteenth aspect of the present invention, the break-open portion on the side of the skin member comprises either of a relief groove projected to a side of a rear face of the skin member and a recess groove formed on a side of a rear face of a bottom portion of the relief groove and the relief groove and a thin wall portion formed by thinning a wall thickness of the bottom portion of the relief groove.

Particularly, according to the thirteenth aspect of the present invention, thermal expansion force or thermal contraction force of the instrument panel caused by temperature rise accompanied by irradiation of solar ray or the like or temperature drop accompanied by vehicular air conditioning Sor the like, can be absorbed by the relief groove portion constituting the break-open portion and therefore, heat resistance of the skin member can be promoted and the design performance in respect of the outlook can be promoted.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plane view showing a break-open shape of an 15 instrument panel for an air bag according to a first embodiment of the present invention; Fig. 2 is a longitudinal sectional view of the instrument panel; Fig. 3 is a longitudinal sectional view enlarging essential portions of Fig. 2; Fig. 4 is a sectional view taken along a line IV-IV of Fig. 1; Fig. 5 is a plane view of the instrument panel for explaining a relationship between a wall thickness of a skin member and a door member according to the instrument panel; Fig. 6 is a longitudinal sectional view enlarging essential portions of an instrument panel for an air bag according to a second embodiment of the present invention; Fig. 7 is a longitudinal sectional view of an instrument panel for an air bag according to a third embodiment of the present invention; /Fig. 8 is a longitudinal sectional view enlarging essential portions of Fig. 7; Fig. 9 is a perspective view enlarging essential portions of Fig. 7; Fig. 10 is a longitudinal sectional view enlarging essential portions of an instrument panel for an air bag according to a fourth embodiment of the present invention; 16 Fig. 11 is a longitudinal sectional view enlarging essential portions of an instrument panel for an air bag according to a fifth embodiment of the present invention; Fig. 12 is a plane view illustrating essential portions showing other embodiment of an instrument panel for an air bag according to the present invention; Figs. 13A, 13B and 13C are plane views illustrating essential portions showing still other embodiments of instrument panels for an air bag according to the present invention; Figs. 14A and 14B are plane views of essential portions showing other example of a skin member.

Fig. 15 is a plane view showing a shape of a break-open portion of a conventional general instrument panel for an air bag; and Fig. 16 is a longitudinal sectional view enlarging essential portions of Fig. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An explanation will be given of embodiments of the present invention in reference to the drawings as follows.

.Fig. 1 is a plane view showing a shape of a break-open portion of an instrument panel for.an air bag according to a 17 first embodiment of the present invention and Fig. 2 is a sectional view of the instrument panel.

The instrument panel 1 incorporates an air bag case 2 storing an air bag for a front seat passenger (not illustrated) at the lower portion in a folded state and covers an opening portion on an upper face of the air bag case 2.

As is apparent from Fig. 2, the instrument panel 1 is integrated by overlapping a skin member 4 having a break-open portion 3 molded by PVC (polyvinyl chloride) or TPO (thermoplastic elastomer of styrene group or olefin group), a door member 6 comprising a resin plate or a metal plate, an end edge portion of which is fixed to an attaching base 5 opposedly to the inner side of the skin member 4, and a foaming layer 7 formed by injecting and foaming a foaming material of polyurethane resin or the like in a space between the o o oooo skin member 4 and the door member 6. Further, the breakopen portion 3 of the skin member 4 is formed in an H-like shape in plane view comprising a linear horizontal breakopen portion 3a and a pair of vertical break-open potions 3b respectively connected orthogonally to both end portions of the horizontal break-open portion 3a in the longitudinal direction at a portion of the skin member 4 in correspondence with an expanded portion of the air bag.

In the instrument panel 1 having the above-described oooo 18 basic constitution, as shown by Fig. 3, the break-open portion 3 of the skin member 4 comprises a relief groove 8 projected to the rear face side of the skin member 4 and formed in an H-like shape in plane view and a recess groove 11 on the rear face side of the bottom of the relief groove 8.

At a portion of the door member 6 opposed to the relief groove 8, a projected portion 9 having an H-like shape in plane view comprising a linear horizontal projected portion 9a and a pair of vertical projected portions 9b connected orthogonally to the both end portions of the horizontal projected portion 9a in the longitudinal direction, is formed to project toward the side of the skin member 4 similar to the break-open portion 3. The projected portion 9 is constructed by bonding open flange portions 9f opposed to each other and raised from the main body of the door member 6 toward the side of the skin member 4 and is constituted to be pushed to open in accordance with expansion of the air bag. That is, the projected portion 9 corresponds to the break-open portion on the side of the door member S• 6.

Further, as is clearly shown by Fig. 3, a thickness tl of the foaming layer 7 between a bottom portion 8a of the relief groove 8 constituting the break-open portion 3 of the 19 skin member 4 and a top portion 9d of the projected portion 9 on the side of the door member 6 opposed to the bottom portion 8a, is set to be relatively smaller than a thickness tO of the foaming layer 7 between the skin member 4 and the door member 6 at other portion. Specifically, the thickness tl of the foaming layer 7 between the bottom portion 8a of the relief groove 8 and the top portion 9d of the projected portion 9 on the side of the door member 6 opposed to the bottom portion 8a, is set in a range of 3/4 through 1/3 of the thickness tO at other portion. For example, when the thickness tO is set to 8 mm, it is preferable to set the thickness tl to 6 mm or smaller and in the above-described range.

Further, as shown by Fig. 4, in respect of the projected portion 9 of the door member 6, a projection height hl at a central portion 9g of the horizontal projected portion 9a

S..

is set to be higher than a projection height hO at other portion. That is, a portion of the projected portion 9 opposed to a central portion of the linear horizontal breakopen portion 3a of the skin member 4, is set to be higher than the heights of portions at both left and right sides thereof.

Further, as shown by Figs. 2 and 5, the wall thickness of the skin member 4 is constituted to be thicker at a So 0 20 portion 4a of the skin member 4 opposed to the door member 6, that is, opposed to substantially an entire region of the upper face of the door member 6 than the wall thickness at the surrounding by which the wall thickness of the breakopen portion 3 which is requested to be thinner than the portion 4a, is ensured to be large to some degree. For example, the wall thickness of the skin member 4 normally falls in a range of 0.8 through 1.0 mm and therefore, the wall thickness T1 at the portion 4a opposed to the door member 6 is set to a range of 1.5 through 2.0 mm which is thicker than a wall thickness TO through 1.0 mm) at the surrounding. Further, a wall thickness T2 at a portion of the break-open portion 3 where the recess groove 11 is formed, is set to 0.5 through 1.0 mm, preferably, through 0.8 mm.

o o According to the instrument panel 1 for an air bag constituted as described above, high rigidity of the total o.

e S of the instrument panel 1 is maintained by increasing the total thickness of the foaming layer 7 between the skin member 4 and the door member 6 opposed to the skin member 4 and further, the foaming material injected between the skin member 4 and the door member 6 does not clog at a portion .o having the small thickness of tl and is filled substantially uniformly over the entire region of the space between the 21 skin member 4 and the door member 6 by flowing to smoothly ride over the top portion 9d of the projected portion 9 on the side of the door member 6 by which the moldability of the instrument panel 1 can excellently be maintained. Along therewith, a positional shift between the trajectory of motion of the projected portion 9 on the side of the door member 6 which is pushed to open in accordance with expansion of the air bag and the break-open portion 3 on the side of the skin member 4, can be dispensed with or much reduced.

Accordingly, no unnecessary shear force is exerted to the foaming layer 7 and many broken pieces of the foaming resin forming the foaming layer 7 can be restrained from scattering as less as possible. Further, predetermined break-open function and extension function of the air bag can be promoted by exerting to concentrate the break force along the o o o break-open portion 3 of the skin member 4.

Further, in the case of the above-described first embodiment, the break-open portion 3 on the side of the skin member 4 is constituted by the relief groove 8 projected to the side of the rear face of the skin member 4 and the recess groove 11 formed on the rear face side of the bottom of the relief groove 8 and therefore, even when thermal 4e expansion force or thermal contraction force is exerted to the instrument panel 1 by temperature rise caused by irraooooo4 22 diation of solar ray or the like or temperature drop caused by vehicular air conditioning or the like in the state of use, the thermal expansion or contraction force can be absorbed by elongation or contraction of the portion of the skin member 4 for forming the relief groove 8 and the design feature in view of outlook can also be promoted.

Further, the break-open portion 3 is formed by constituting the wall thickness T1 of the portion 4a of the skin member 4 opposed to the door member 6 thicker than the wall thickness TO at the surrounding and therefore, at the breakopen portion 3 necessitating a predetermined wall thickness difference in respect of the portion 4a to ensure the uniformity of the break-open position of the skin member 4, provision of wall thickness for preventing necessary strength from lowering is facilitated and the break-open e e 9: function and the extension function of the break-open poro..

tion 3 can be promoted while highly maintaining the uniform- 9. ity of the break-open position of the skin member 4.

Further, by setting the projection height hi of the central portion 9g of the projected portion 9 in the door 9S8 member 6 opposed to the central portion of the horizontal break-open portion 3a of the skin member 4, higher than the projection height hO on the both sides, the break-open portion 3 of the skin member 4 is broken to open from the 9oo*99 23 central portion and the expansion function of the air bag can further be promoted.

Fig. 6 is a sectional view of essential portions of an instrument panel for an air bag according to a second embodiment of the present invention.

According to the second embodiment, the break-open portion 3 of the skin member 4 is constituted only by a recess groove 10 formed on the rear face side of the skin member 4 and the thickness tl of the foaming layer 7 between a bottom portion 10a of the recess groove 10 and the top portion 9d of the projected portion 9 which is projected from the side of the door member 6 opposedly to the bottom portion 10a, is set relatively small within the range of 3/4 through 1/3 of the thickness tO of the foaming layer 7 between the skin member 4 and the door member 6 at other portion as has been described. Other constitution remains the same as that of the first embodiment and therefore, same notations are attached to corresponding portions and an explanation thereof will be omitted.

Also in respect of the second embodiment, similar to the first embodiment, it is possible to maintain high rigidity of the total of the instrument panel 1, to maintain the molderability excellently, to reduce the positional shift between the trajectory of motion of the projected portion 9 0 24 on the side of the door member 6 that is pushed to open in accordance with expansion of the air bag and the break-open portion 3 on the side of the skin member 4 thereby restraining as less as possible broken pieces of foamed resin from scattering and to promote the predetermined break-open function and the extension function of the air bag by concentrating the break force along the break-open portion 3 of the skin member 4.

Fig. 7 is a longitudinal sectional view of essential portions showing an instrument panel 1 for an air bag according to a third embodiment of the present invention. The instrument panel 1 of the third embodiment is provided with the basic constitution similar to that of the first embodio ment.

In such a basic constitution, according to the embodi- S ment, as shown by Fig. 8 by enlarging a portion of Fig. 7, the break-open portion 3 of the skin member 4 comprises the S• recess groove 10 formed on the rear face side of the skin member 4 as is similar to the second embodiment.

.o ~Meanwhile, the projected portion 9 on the side of the door member 6 is constituted by a recess portion 19 having o an H-like shape in plane view which is integrally formed to project toward the side of the skin member 4 at a portion of the door member 6 opposed to the recess groove 10 constitut- 25 ing the break-open portion 3 of the skin member 4. In this case, a wall thickness tll of the top portion 9d of the projected portion 9 comprising the recess portion 19, is formed thinner than a wall thickness tl0 at other portion of the projected portion 9.

Further, the thickness tl of the foaming layer 7 between the bottom portion 10a of the recess groove 10 and the top portion 9d of the recess portion 19 that is formed to project from the side of the door member 6 opposedly to the bottom portion 10a, is set relatively small within a range of 3/4 through 1/3 of the thickness tO of the foaming layer 7 between the skin member 4 and the door member 6 at other portion.

a.

Further, according to the third embodiment, as shown by Fig. 7, an engagement piece 23 having a section in a substantially L-like shape which is engageable to an end edge portion 5a of the attaching base 5, is integrally formed at a position proximate to all the peripheral portions or three peripheral portions of the door member 6 and a clearance 24 for absorbing thermal expansion is constituted at an engaging portion for engaging the engagement piece 23 and the end edge portion 5a of the attaching base 5 by which the door member 6 is supported by the attaching base 5 freely movably within the range of the clearance 24.

26 Further, a wall member 25 that is arranged on the external side of the peripheral edge of the opening of the air bag case 2, is integrally provided to the side of the door member 6. As shown by Fig. 9, through holes 26 having a rectangular shape are formed in the wall member 25 at pertinent intervals. Further, engaging portions 27 in a channel-like shape which can be projected to the external side of the wall member 25 by being inserted through the through holes 26 from the side of the air bag case 2, are installed. Further, in a state where the engaging portions 27 in a channel-like shape are projected to the external side by being respectively inserted through the through holes 26 in a rectangular shape of the wall member 25, a fixing member 28 in a shape of a locking bar is inserted e *e through over the projected portions of the engaging portions 27 by which the door member 6 is fixedly connected to the air bag case 2.

Also in the third embodiment, similar to the first embodiment, it is possible to maintain high rigidity of the total of the instrument panel 1, to maintain the excellent moldability and to reduce the positional shift between the trajectory of motion of the projected portion 9 on the side of the door member 6 which is pushed to open by breaking the 27 thin top portion 9d of the recess portion 19 in expansion of the air bag and the break-open portion 3 on the side of the skin member 4 thereby promoting the break-open function of the total of the instrument panel i.

Further, the top portion 9d of the projected portion 9 is formed by a thin wall and accordingly, when thermal expansion force or thermal contraction force is exerted on the door member 6 by heating in accordance with irradiation of solar ray or the like or cooling in accordance with vehicular air conditioning or the like, the thermal expansion force or the thermal contraction force can be alleviated by absorbing the force by elongation or contraction caused by bending deformation of the thin top portion 9d.

In this way, thermal deformation of the door member 6 can be S: prevented by operating the projected portion 9 as a thermal "deformation absorbing portion.

~Further, conventionally, in order to prevent thermal deformation of the door member, as a material for constituting the door member, a material having the low thermal expansion coefficient that is approximately equal to the thermal expansion coefficient of the skin member or the like, has been used or the door member has been divided and o clearances for absorbing the thermal expansion have been provided between the divided portions of the door member.

28 However, when the projected portion 9 having the thin top portion 9d is installed integrally with the door member 6 as mentioned above, while using a material having the thermal expansion coefficient larger than those of materials for constituting the skin member 4 and the foaming layer 7 and using an inexpensive material that is necessary and sufficient for satisfying the strength and function required as the door member 6 and while forming the total of the door member 6 in an integrated shape without dividing the door member 6, the problem of deterioration in outlook caused by thermal deformation of the total of the instrument panel 1 or the like can be resolved.

Further, according to the third embodiment, when the thermal expansion force or the thermal contraction force is exerted on the door member 6, the thermal expansion force or the thermal contraction force can be alleviated by being absorbed by the clearance 24 for absorbing the thermal expansion that is constituted at the engaging portion for o engaging the engagement piece 23 on the side of the door member 6 and the end edge portion 5a of the attaching base Accordingly, compared with the case where the end edge portion of the door member 6 is fixed to the attaching base by using bolts and nuts, not only reduction in parts and assembling cost can be achieved by dispensing with the use 29 of the bolts and the nuts, but function of preventing the thermal deformation accompanied by heating or cooling of the total of the instrument panel can be achieved properly and firmly.

Further, according to the third embodiment, the door member 6 which becomes freely movable by forming the clearance 24 for absorbing thermal expansion is fixedly connected to the air bag case 2 via the fixing member 28 in a shape of a locking bar and therefore, disengagement or detachment of the door member 6 in expanding and extending the air bag can firmly be prevented. Further, by adopting the locking bar structure as the fixing means, the assembling operation of the total can be facilitated.

Fig. 10 is a longitudinal sectional view enlarging essential portions of an instrument panel for an air bag according to a fourth embodiment of the present invention.

According to the fourth embodiment, a recess groove which is recessed in respect of the side of the door member 6 is formed at the top portion 9d of the projected portion 9 comprising the recess portion 19 which is formed to integrally project from a portion of the door member 6 opposed to the break-open portion 3 on the side of the skin member 4 toward the break-open portion 3. In this way, the recess groove 20 may be formed at the top portion 9d of the recess 30 portion 19 as means for thinning the top portion 9d of the projected portion 9 comprising the recess portion 19 and also in this case, the operation and effect similar to those in the third embodiment can be achieved.

Fig. 11 is a longitudinal sectional view enlarging essential portions of an instrument panel for an air bag according to a fifth embodiment of the present invention.

According to the fifth embodiment, recess portions 21 having a projection dimension smaller than that of the recess portion 19 directed to the side opposed to the side of the skin member 4, are integrally formed at both side base edge portions of the recess portion 19 which is formed to integrally project from a portion of the door member 6 opposed to the break-open portion 3 on the side of the skin member 4 toward the break-open portion 3 with the thinned top portion 9d.

**In this case, the thermal expansion force or the thermal contraction force exerted on the door member 6 can be alleviated by being absorbed not only by the elongation and o* contraction caused by the bending deformation of the thinned top portion 9d of the recess portion 19 but by the elongation and contraction by the bending deformation at the recess portions 21 on the both sides of the recess portion 19 and therefore, the thermal deformation of the total of 31 the instrument panel 1 can further firmly be prevented.

An explanation has been given of the instrument panels for an air bag according to the respective embodiments, in each of which the break-open portion 3 on the side of the skin member 4 and the projected portion 9 on the side of the door member 6 are formed in an H-like shape in plane view.

Otherwise, as shown by Fig. 12, both of the break-open portion 3 on the side of the skin member 4 and the projected portion 9 on the side of the door member 6 may be formed in a substantially double Y-like shape which is constituted by the linear horizontal break-open portion 3a or the linear horizontal projected portion 9a and a pair of the vertical :i break-open portions 3c or the vertical projected portions 9c which are connected to the horizontal break-open portion 3a or the horizontal projected portion 9a by being divided and expanded in a V-like shape respectively from the both end portions of the horizontal break-open portion 3a or the horizontal projected portion 9a in the longitudinal direction.

Further, as shown by Figs. 13A through 13C, the breakopen portion 3 on the side of the skin member 4 may be Sformed in an I-like shape in plane view comprising only the linear horizontal break-open portion 3a whereas the projected portion 9 which is the break-open portion on the side of 32 the door member 6 may be formed in a substantially double Ylike shape, an H-like shape, a substantially double channel shape or the like in plane view by which the extended portions of the door member 6 and the skin member 4 are prevented from coinciding with each other.

According to the example of Fig. 13A, the break-open portion 3 on the side of the skin member 4 is formed in an I-like shape in plane view comprising only the linear horizontal break-open portion 3a and the projected portion 9 constituting the break-open portion on the side of the door member 6 is formed in a substantially double Y-like shape comprising a horizontal projected portion 9a in a short linear shape arranged at a location overlapping the horizontal break-open portion 3a except both end portions 3al in the longitudinal direction of the horizontal break-open portion 3a on the side of the skin member 4, and a pair of vertical projected portions 9c connected to the horizontal projected portion 9a by being divided and expanded in a Vlike shape respectively from both end portions of the horizontal projected portion 9a in the longitudinal direction.

According to the example of Fig. 13B, the break-open portion 3 on the side of the skin member 4 is formed in the above-described I-like shape in plane view and the projected portion 9 constituting the break-open portion on the side of 33 the door member 6 is formed in an H-like shape in plane view comprising the above-described linear horizontal projected portion 9a and the pair of vertical projected portions 9b respectively connected to the both end portions of the horizontal projected portion 9a orthogonally to the horizontal projected portion 9a.

According to the example of Fig. 13C, the break-open portion 3 on the side of the skin member 4 is formed in the above-described I-like shape in plane view and the projected portion 9 constituting the break-open portion on the side of the door member 6 is formed in a substantially double channel shape in plane view comprising the above-described linear horizontal projected portion 9a and a pair of vertical projected portions 9e in a substantially channel shape which are respectively connected to the both end portions of the horizontal projected portion 9a in the longitudinal direction and which are opened in directions opposed to each other.

d In this way, by forming the break-open portion 3 on the o• side of the skin member 4 in the simple I-like shape in plane view comprising only the linear horizontal break-open portion 3a, even when the instrument panel 1 per se is provided with a complicated three-dimensional shape, the break-open portion 3 can be formed at a proper position of 34 the skin members 4 with no shift by using a simple breakopen portion fabricating jig or using a molding die having a simple constitution for providing the skin member 4 with thickness deviation, whereby fabrication of the break-open portion 3 of the skin member 4 is facilitated, the reduction in fabrication cost is achieved, troublesome adjustment of modification of positional shift or the like is not needed and the fabrication efficiency of the break-open portion 3 of the skin member 4 can be promoted.

Further, the horizontal break-open portion 3a of the skin member 4 which is formed at the proper position and the horizontal projected portion 9a of the door member 6 can be made to coincide with each other with no positional shift.

Further, when the projected portion 9 on the side of the door member 6 in the above-described substantially double Ylike shape, H-like shape or substantially double channel shape, is broken to open, by concentratingly exerting the break force to the both end portions 3al in the longitudinal direction of the horizontal break-open portion 3a on the side of the skin member 4 the shape of which does not totally coincide with the shape of the projected portion 9 on the .e side of the door member 6, the break-open portion 3 can be broken with certainty since the break-open portion 3 is provided with the simple I-like shape having no divided 35 portions by which the break-open function equivalent or superior to that in the case of the break-open portion 3 having the above-described substantially double Y-like shape or the H-like shape in plane view, can be achieved. Thereby, when the air bag is expanded, a portion of the skin member 4 in correspondence with the both end portions in the longitudinal direction of the horizontal break-open portion 3a and broken pieces of foamed resin for forming the foamed layer 7 can be prevented from scattering to the surrounding and further, the break-open function of the break-open portion 3 and the extending function of the air bag can be achieved in a predetermined manner.

Further, according to the cases of Figs. 13A through 13C where only the linear horizontal break-open portion 3a of the break-open portion 3 on the side of the skin member 4 is formed by an I-like shape in plane view, an effect similar to those in the above-described respective embodiments can be achieved by setting only the thickness tl of the foaming layer 7 between the top portion 9d of the projected portion 9 in correspondence with the horizontal break-open portion 3a on the side of the skin member 4 and the bottom portion 8a of the relief groove 8 or the bottom portion of the recess groove 10 for constituting the horizontal break-open portion 3a within a range of 3/4 through 1/3 of 36 the thickness tO at other portion, in the projected portions 9 on the side of the door member 6 having a substantially double Y-like shape, an H-like shape and a substantially double channel shape in plane view.

Further, the break-open portion 3 of the skin member 4 is not limited to the break-open portion comprising the relief groove 8 projected to the rear face side of the skin member 4 and the recess groove 11 formed on the rear face side of a bottom portion thereof shown by Fig. 3 or the break-open portion comprising the recess groove 10 formed on the rear face side of the skin member 4 shown by Fig. 6 but may be, for example, a break-open portion 3 provided with o oo the relief groove 8 projected to the rear face side of the skin member 4 where a wall thickness T2 of the bottom portion 8a is made to be thinner than a wall thickness T1 at other portion of the skin member 4 as shown by Fig. 14A.

S Further, as shown by Fig. 14B, the break-open portion 3 may be constituted by a thin wall portion 30 where the wall S thickness is thinned on the rear face side of the skin g member 4.

S.

Or 0 *oo o

Claims (13)

1. An instrument panel for an air bag constituted by injecting and foaming a foaming material between a skin member having a break-open portion at a location thereof in correspondence with an expanded portion of the air bag and a door member opposed to the skin member thereby integrating the skin member, the door member and the foaming layer: wherein a projected portion is projected from a portion of the door member opposed to the break-open portion of the skin member and a thickness between the projected portion and the break-open portion of the skin member is set to be small relative to a thickness of other portion. rooe

2. The instrument panel for an air bag according to Claim i, wherein the break-open portion of the skin member is constituted by a relief groove projecting to a rear face side and a recess groove formed on the rear face side of a bottom portion of the relief groove and a thickness between e• the bottom portion of the relief groove and the projected portion of the portion of the door member opposed to the bottom portion is set to be smaller than the thickness of the other portion.

3. The instrument panel for an air bag according to Claim i, wherein the break-open portion of the skin member 38 is a recess groove on a rear face side and a thickness between a bottom portion of the recess groove and the pro- jected portion of the portion of the door member opposed to the bottom portion is set to be smaller than the thickness of the other portion.

4. The instrument panel for an air bag according to Claim i, wherein the projected portion of the portion of the door member which is pushed to open in accordance with expansion of the air bag is constituted by bonding opening ends of the door member projected toward a side of the skin member.

The instrument panel for an air bag according to Claim i, wherein the projected portion of the portion of the S.. door member which is pushed to open in accordance with expansion of the air bag is constituted by a recess portion projected integrally with the door member toward a side of the skin member and a top portion the recess portion is 9* formed in a thin wall.

6. The instrument panel for an air bag according to Claim i, wherein a wall thickness of a portion of the skin member opposed to substantially an entire region of a sur- *o face of the door member is set to be thicker than a wall thickness at a surrounding portion.

7. The instrument panel for an air bag according to 39 Claim i, wherein a thickness between the break-open portion of the skin member and the projected portion of the portion of the door member opposed to the break-open portion is set to be 3/4 through 1/3 of a thickness of other portion.

8. The instrument panel for an air bag according to Claim i, wherein the break-open portion of the skin member is formed in an H-like shape in a plane view constituted by a linear horizontal break-open portion and vertical break- open portions respectively connected orthogonally to both end portions of the horizontal break-open portion in a longitudinal direction, or a substantially double Y-like shape in a plane view constituted by a linear horizontal *999 break-open portion and vertical break-openportions respec- tively connected to the horizontal break-open portion by being divided and expanded in a V-like shape from both end %:portions of the horizontal break-open portion in the longi- S9.9. tudinal direction, or in an I-like shape in a plane view 9"9. constituted only by a linear horizontal break-open portion, 9 and a thickness between at least the linear horizontal break-open portion in the break-open portion of each of the plane view shapes and the projected portion of the portion of the door member opposed to the linear horizontal break- open portion is set to be small relative to a thickness of other portion. 40

9. The instrument panel for an air bag according to Claim 8, wherein a projection height of the projected por- tion of the door member opposed to a central portion of the horizontal break-open portion of the skin member is set to be higher than projection heights on both sides thereof.

An instrument panel for an air bag constituted by injecting and foaming a foaming material between a skin member having a break-open portion at a location thereof in correspondence with an expanded portion of the air bag and a door member having a break-open portion at a location in correspondence with the expanded portion of the air bag and arranged at a position on a side of the air bag opposedly to the skin member thereby integrating the skin member, the door member and the foaming layer: wherein the break-open portion on a side of the skin member is formed in an I-like shape in a plane view compris- ing only a linear horizontal break-open portion; and wherein the break-open portion on a side of the door .o member comprises a linear horizontal break-open portion positioned to overlap the horizontal break-open portion on the side of the skin member except both end portions in a longitudinal direction of the horizontal break-open portion and vertical break-open portions respectively connected to 41 both end portions in the longitudinal direction of the horizontal break-open portion.

11. The instrument panel for an air bag according to Claim 10, wherein the break-open portion on the side of the door member is formed in either of an H-like shape in a plane view comprising the linear horizontal break-open portion and vertical break-open portions respectively con- nected orthogonally to both end portions in the longitudinal direction of the horizontal break-open portion, a substan- tially double Y-like shape in a plane view comprising the linear horizontal break-open portion and vertical break-open portions connected to the horizontal break-open portion by e being respectively divided and expanded from the both end portions in the longitudinal direction of the horizontal break-open portion in a V-like shape and a substantially double channel shape in a plane view comprising the linear horizontal break-open portion and vertical break-open por- *99, tions in a channel-like shape connected to the both end portions in the longitudinal direction of the horizontal break-open portion.

12. The instrument panel for an air bag according to Claim 10, wherein the break-open portion on the side of the skin member comprises either of a recess groove formed on a side of a rear face of the skin member and a thin wall 42 portion formed by thinning a wall thickness on the side of the rear face of the skin member.

13. The instrument panel for an air bag according to Claim 10, wherein the break-open portion on the side of the skin member comprises either of a relief groove projected to a side of a rear face of the skin member and a recess groove formed on a side of a rear face of a bottom portion of the relief groove and the relief groove and a thin wall portion formed by thinning a wall thickness of the bottom portion of the relief groove. DATED this 13th day of February, 1998. TOYO TIRE RUBBER CO., LTD. WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VIC 3122 AUSTRALIA o D. S go oooo