Abstract:
A sub panel concealing an airbag is mounted in the instrument panel of a vehicle. The sub panel covering a portion of the instrument panel appears to be part of the instrument panel. The inner surface of the sub panel has cleavage grooves that split open during a vehicle collision allowing the airbag to expand, protecting the passenger. The sub panel and airbag unit are replaceable after the airbag is deployed, restoring the instrument panel functionality. In the preferred embodiment, the sub panel covers a portion of the instrument panel on the passenger side of the vehicle.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a vehicle instrument panel. More specifically, the present invention relates to a vehicle instrument panel with a replaceable sub panel which conceals an airbag. 
     Referring to FIG. 22, prior art vehicles, such as cars, provide for passenger safety with an airbag (not shown) installed in a section of an instrument panel  1 . During a collision, an airbag unit  2  is activated allowing the airbag to expand, protecting passengers (not shown). 
     A cleavage groove  3  splits open when the airbag expands. Cleavage groove  3  is disposed along an inner surface of instrument panel  1 . Airbag lid parts  4 , disposed within instrument panel  1 , also open when cleavage groove  3  splits. Because cleavage groove  3  faces an inner surface of instrument panel  1 , it is hidden from view. The aesthetic appearance of instrument panel  1  is improved by concealing the presence of the airbag and associated cleavage groove  3 . 
     However in the prior art, because cleavage groove  3  is disposed directly on an inner surface of instrument panel  1 , after airbag unit  2  is activated, entire instrument panel  1  must be replaced when repairing the vehicle. This increases the cost and complexity of repairing the vehicle. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is an object of the present invention to overcome the drawbacks of the prior art. 
     It is another object of the present invention to provide an attractive instrument panel that effectively conceals an airbag. 
     It is yet another object of the present invention to provide a sub panel airbag assembly that allows easy replacement of a deployed airbag. 
     Briefly stated, the present invention provides a sub panel concealing an airbag mounted in the instrument panel of a vehicle. The sub panel covering a portion of the instrument panel appears to be part of the instrument panel. The inner surface of the sub panel has cleavage grooves that split open during a vehicle collision allowing the airbag to expand, protecting the passenger. The sub panel and airbag unit are replaceable after the airbag is deployed, restoring the instrument panel functionality. In the preferred embodiment, the sub panel covers a portion of the instrument panel on the passenger side of the vehicle. 
     According to an embodiment of the invention, there is provided a vehicle instrument panel comprising: an instrument panel body having an opening; a sub panel; the opening being closed by the sub panel; an airbag disposed within the sub panel; the sub panel having at least one of a cleavage groove disposed on a surface of the sub panel whereby when the airbag is deployed, the cleavage groove splits open; and the sub panel covering less than all of the instrument panel body. 
     According to another embodiment of the invention. there is provided an instrument sub panel comprising: a sub panel unit covering less than all of an instrument panel of a vehicle; the sub panel unit being removably insertable in the instrument panel; at least a first cleavage groove disposed on a surface of the sub panel unit whereby at least the first cleavage groove is cleavable during a vehicle collision by the airbag; and means for removably securing the sub panel unit to the instrument panel whereby the sub panel unit appears to be integrally associated with the instrument panel. 
     The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective drawing of the instrument panel relating to the present invention. 
     FIG. 2 is a cross-section drawing along line A—A of FIG.  1 . 
     FIG. 3 is an expanded perspective drawing of the essential parts of the section attached to the sub panel of FIG.  1 . 
     FIG. 4 is a cross-section drawing along line B—B of FIG.  1 . 
     FIG. 5 is a cross-section drawing along line C—C of FIG.  1 . 
     FIG. 6 is a cross-section drawing similar to FIG. 3 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 7 is a cross-section drawing similar to FIG. 3 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 8 is a cross-section drawing similar to FIG. 3 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 9 is a cross-section drawing similar to FIG. 3 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 10 is a cross-section drawing similar to FIG. 2 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 11 is a cross-section drawing similar to FIG. 2 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 12 is a cross-section drawing similar to FIG. 2 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 13 is a cross-section drawing similar to FIG. 2 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 14 is a cross-section drawing similar to FIG. 2 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 15 is a cross-section drawing similar to FIG. 2 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 16 is a cross-section drawing similar to FIG. 2 of another example of a sub panel shown in FIGS. 1-5. 
     FIG. 17 is a perspective drawing of the instrument panel of yet another embodiment of the invention. 
     FIG. 18 is an exploded perspective drawing of an airbag lid part and a panel body representing another embodiment of the invention. 
     FIG. 19 is a perspective drawing showing the condition where the airbag lid part and the panel body of FIG. 18 are joined together. 
     FIG. 20 is a partial expanded cross-section showing the condition where a laminate sheet is attached to the core material of FIG.  19 . 
     FIG. 21 shows the condition where the sub panel of FIG. 19 is being vacuum molded. 
     FIG. 22 is a schematic perspective drawing of an example of the instrument panel of the prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, an instrument panel  10  of a vehicle (not shown), such as a car, has an instrument panel body  11 . Instrument panel body  11  transversely extends from one side of the vehicle to the other. A central panel (cluster lid)  12  is centrally disposed on instrument panel body  11 . A sub panel  13  is disposed on the passenger side of the vehicle. 
     Referring to FIGS. 1 through 3. instrument panel body  11  includes a forward section  11   a  disposed along its front edge and a backward inclining section  11   b  which is continuous with, but extending away from forward section  11   a . Forward section  11   a  includes a forward inclining piece  11   c  and a horizontal piece  11   d . A ridge line  11   e  is formed where horizontal piece  11   d  joins with backward inclining section  11   b . A longitudinal defroster opening  14  is disposed in horizontal piece  11   d . Air is blown through air openings  15   a . A grill  15  covers defroster opening  14 . 
     Referring to FIG. 2, a steering member  16  is disposed within instrument panel body  10 . A bracket  17  is welded onto the section of steering member  16  that corresponds to the passenger side. The front end of an airbag unit  18  is anchored to bracket  17  by a bolt  19 . Airbag unit  18  inclines diagonally upwards from bracket  17  towards instrument panel body  11 . An airbag expansion opening  18   a  is disposed towards an inner surface of instrument panel body  11 . 
     Referring again to FIGS. 1 through 3, an expansion opening  20 , allows the airbag (not shown) of airbag unit  18  to expand. The front edge of expansion opening  20  extends along ridge line  11   e . The back edge of expansion opening  20  extends along a passenger seat edge (back edge part)  21 . One side edge of expansion opening  20  extends along a central panel left side edge  12   a  of central fix panel  12 . The other edge extends along an instrument panel left side edge  22  of instrument panel body. Central panel left side edge  12   a  of central panel  12  extends from passenger seat edge  21  to ridge line  11   e . Air is centrally directed using a louver  12   b . A liquid crystal display  12   c  of the AV system, along with other instrumentation are disposed on central panel  12 . 
     Referring to FIGS. 2 and 3, a panel attachment edge  23  is disposed along the perimeter of expansion opening  20 . Panel attachment edge  23  has a U-shaped cross-section which includes an inner perimeter wall  23   a , an outer perimeter wall  23   b , and a bottom wall  23   c . A panel attachment groove  23   d  is formed between inner perimeter wall  23   a  and outer perimeter wall  23   b . A flange  13   a  disposed along the perimeter of sub panel  13  fits within panel attachment groove  23   d . Additionally, axial projections  23   e  are tapered and protrude outward towards airbag unit  18 . Axial projections  23   e  are formed in bottom walls  23   c  at various intervals. 
     Referring now to FIGS. 1,  2  and  5 , the inner surface of the perimeter of sub panel  13  has a plurality of latching tabs  24 . Plurality of latching tabs  24  attach sub panel  13  to instrument panel body  11  along the edges of expansion opening  20 . Additionally, latching pieces  25  are formed along the inner edge surfaces of sub panel  13  which are parallel to ridge line  11   e . Joining holes  25   a  are formed in latching pieces  25 . Axial projections  23   e  fit into joining holes  25   a . Latching pieces  25  are affixed to bottom wall  23   c  by tapping screws  26 . Tapping screws  26  screw into axial projections  23   e.    
     Sub panel  13  is laminated in three layers in the following sequence: a core material  27 , a foam layer  28 ; and a surface covering  29 . Core material  27  is formed from resin by injection molding. A cleavage groove  30  is centrally formed on the inner surface of sub panel  13 . Cleavage groove  30  is H-shaped and includes a cleavage groove  30   a  running parallel to ridge line  11   e , forming the bar in the H-shape, and a pair of cleavage grooves  30   b  running perpendicular to ridge line  11   e  and forming the uprights in the H-shape. Cleavage groove  30  is seamless and cannot be seen from the vehicle interior. Cleavage groove  30  traverses core material  27  and foam layer  28 . Cleavage groove  30  is easily cleaved by the expansion pressure of the airbag. 
     Airbag lid parts  31  are disposed below sub panel  13 . Airbag lid parts  31  open when cleavage groove  30  cleaves through the expansion pressure of the airbag. Airbag lid parts  31  are formed above and below cleavage groove  30   a . An air conditioning hole  131  is formed on a side edge to sub panel  13 . A louver  32  is attached to air conditioning hole  131 . 
     A large section of instrument panel  10  located on the passenger side of the vehicle is covered by sub panel  13 . This improves the overall aesthetic appearance of instrument panel  10 . When a vehicle collision occurs, airbag lid parts  31  open allowing an airbag to expand outward into the interior region of the vehicle protecting the passenger. Instrument panel  10  is restored by replacing only sub panel  13 . This reduces repair costs and simplifies restoration of the vehicle after a collision. 
     The aesthetic appearance of instrument panel  10  is enhanced because ridge line  11   e  and the front edge of sub panel  13  coincide, making it appear as though the front edge of sub panel  13  is continuous with instrument panel body  11 . Furthermore, central panel left side edge  12   a  of central panel  12  and the right side edge of sub panel  13  coincide, contributing to the continuous look of instrument panel body  11  and sub panel  13 . 
     EXAMPLES 
     In Mode 1 of the embodiment described above, (see FIG. 4 for example) sub panel  13  is made using a three layer construction consisting of core material  27 , foam layer  28 , and surface covering  29 . However, other constructions are possible. 
     Referring to FIG. 6, a one layer construction consisting of only core material  27 , is illustrated. Cleavage groove  30 , which opens along an inner surface of core material  27 , closely approaches the outer surface of core material  27 . 
     Referring to FIG. 7, sub panel  13  has a two layer construction of core material  27  and surface covering  29 . Cleavage groove  30  traverses all of core material  27  stopping just at the inner surface of surface covering  29 . 
     Referring to FIG. 8, sub panel  13  can also be made using a four layer construction in which core material  27 , a thermal insulation layer  27   a , foam layer  28 , and surface covering  29  are laminated sequentially. Cleavage groove  30  extends through core material  27 , thermal insulation layer  27   a , and foam layer  28 , again stopping just at the inner surface of surface covering  29 . In forming the four layer construction, thermal insulation layer  27   a , foam layer  28 , surface covering  29  are formed in advance and set inside the cavity of an injection molding die. Core material  27  is then formed by injecting melted resin into the injection molding die containing the three layer construct. Thermal insulation layer  27   a  prevents foam layer  28  from melting due to the heat from the melted resin. 
     Referring to FIGS. 9-12, support pieces (support protrusions)  40  protrude on an inner surface of core material  27 , described above. Latching holes  40   a  are provided on support pieces  40 . Latching is achieved by passing latching tabs  41  (which protrude from airbag unit  18 ) through latching holes  40   a . This stabilizes and supports airbag unit  18  within instrument panel  10 . 
     Referring now to FIGS. 13-16, core material  27  includes an airbag lid part  50  and a panel body  51 . Airbag lid part  50  is centered and surrounded by panel body  51 . Airbag lid part  50  and panel body part  51  of core material  27  is formed by using a multicolored molding heat welding process that uses resin materials with differing material values. Airbag lid part  50  comprises two airbag lid parts  31 , which are divided by cleavage groove  30 . 
     The following parts are made of core material  27  with the following properties: 
     Airbag Lid Part  50   
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Bending elasticity coefficient: 
                 10,000 Kg/cm 2  ˜ 25,000 Kg/cm 2   
               
               
                   
                 Shrinkage factor (%): 
                 4/1000 ˜ 8/1000 
               
               
                   
                 Linear expansion coefficient: 
                 4 × 10 −5 /° C. ˜ 10 × 10 −6 /° C. 
               
               
                   
                   
               
             
          
         
       
     
     Panel Body Part  51   
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Bending elasticity coefficient: 
                 700 Kg/cm 2  ˜ 7,000 Kg/cm 2   
               
               
                 Shrinkage factor (%): 
                 4/1000 ˜ 10/1000 
               
               
                 Linear expansion coefficient: 
                 2 × 10 −5  ˜ 12 × 10 −6 /° C. ˜ 12 × 10 −5 / 
               
               
                   
                 ° C. 
               
               
                   
               
             
          
         
       
     
     Airbag lid part  50  of sub panel  13  is formed from an easily bendable material, while the part surrounding airbag lid part  50  is formed from a highly rigid material. This results in sub panel  13  which looks like it is continuous with instrument panel body  11 . When airbag unit  18  is activated, airbag lid part  50  easily opens. By forming airbag lid part  50  and panel body part  51  of resin materials having approximately the same material values for shrinkage factor and linear expansion coefficient an instrument panel  10  has excellent heat cycle resistance with little deformation. 
     Support pieces  40  are disposed on airbag lid part  50 . Each of latching tabs  41  of airbag unit  18  pass through latching holes  40   a  and are latched. 
     Referring to FIGS. 9-16, the construction is essentially the same and, therefore, use the same numbers as shown in FIGS. 1-8. The descriptions are likewise abbreviated. 
     Referring to FIG. 17, a vehicle has a lid  110  (this lid opens when the display device, which is housed within the instrument panel, is pushed during navigation activation) which comprises part of a pop-up style navigation system located at the top part of central panel  12 . The side edges of lid  110  coincide with the side edges of sub panel  13 . The side edges of lid  110  extend to ridge  11   e . This enhances the look of instrument panel body  11  and makes it appear to be a continuous structure. 
     Referring now to FIGS. 18-21, sub panel  13  includes a laminate sheet  71  affixed on a core material  70 . Core material  70  has separate members which include an airbag lid part  72  and a panel body part  73 . Panel body  73  surrounds airbag lid part  72 . Airbag lid part  72  and panel body part  73  are fitted together. 
     Panel body part  73  is constructed from a normal PPC material or other appropriate material. Airbag lid part  72  is constructed from TPO material or TEO material or other appropriate material which has good low temperature properties. A joining part  74  protrudes along an edge of panel body part  73 . Joining part  74  fits within a receiving groove  75  disposed on airbag lid  72 . 
     Referring to FIGS. 19 and 20, both body panel  73  and airbag lid  72  are joined by force fitting them into there respective opening. A guide pin  84  can be formed on panel body part  73  to correctly position airbag lid part  72 . 
     Referring to FIG. 19, the surface of core material  70  is coated with an adhesive  76 . Adhesive  76  covers panel body part  73  and airbag lid part  72 . Suitable examples of adhesive  76  include rubber, butyl rubber, or styrene type adhesives. Other suitable adhesives could be used. 
     Referring to FIGS. 20 and 21, core material  70  is placed in a vacuum receiving mold  78  of a vacuum molding device  77 . Laminate sheet  71  is placed on the surface of core material  70  and vacuum is applied using a vacuum source  79 . Vacuum source  79  can include a vacuum tank with a vacuum attachment to conduct the vacuum where required. Laminate sheet  71  is a sheet material has a surface covering  80  and a foam layer  81 . Surface covering  80  is made of a TPO material having good low temperature properties. Foam layer  81  is a PPF foam body and other appropriate material. In order to improve the adhesion between core material  70  and laminate sheet  71 , a drawing process can be used or jagged grooves can be formed on the surface of core material  70 . Alternatively, jagged grooves  82  can be formed on laminate sheet  71 . In order to conduct the vacuum, small vacuum suction holes are formed in core material  70 . Other embodiments are possible, for example, the core material could be formed from metal. 
     Referring to FIG. 21, sub panel  13  is complete when removed from the mold and cut along a dashed line  83 . 
     By constructing panel body part  73  and airbag lid part  72  separately, core material  70  is easily and inexpensively produced without having to use the two color molding device indicated in FIGS. 13-16. 
     Furthermore, since vacuum molding device  77  is used for the adhesion between laminate sheet  71  and core material  70  only has a vacuum receiving mold  78 , the cost is kept low. In this way, sub panel  13  is easily and inexpensively produced. 
     For surface coverings  29  and  80  that cover cleavage groove  30 , a material having the following properties is used: 
     at −40 degrees C (low temperature); 
     tensile strength 250×9.8 N/cm 2  (250 Kgf/cm 2 )˜500×9.8 N/cm 2  (500 Kgf/cm 2 ); 
     extension percentage 50(%) or greater, and 
     tearing strength 10×9.8 N/cm 2  (10 Kgf/cm 2 ) or greater; 
     at 23 degrees C (normal temperature); 
     tensile strength 50×9.8 N/cm 2  (50 Kgf/cm 2 )˜100×9.8 N/cm 2  (100 Kgf/cm 2 ); 
     extension percentage 100(%) or greater, and 
     tearing strength 10×9.8 N/cm 2  (10 Kgf/cm 2 ) or greater; and 
     at 85 degrees C (high temperature); 
     tensile strength 10×9.8 N/cm 2  (10 Kgf/cm 2 )˜100×9.8 N/cm 2  (100 Kgf/cm 2 ); 
     extension percentage 150-500(%) or greater; and 
     tearing strength 5×9.8 N/cm 2  (5 Kgf/cm 2 ) or greater. 
     Some examples of surface coverings  29  and  80  having the above properties include the following: 
     1. TEO (TPO) thermoplastic olefin 
     2. TPU (PUR) thermoplastic urethane 
     3. TPVC (PVC) vinyl chloride 
     4. TPEE (TEEE) thermoplastic ester elastomer 
     5. SBC (TPS) styrene (polysterene, polybutadiene, or polyisoprene) and the like. 
     The method for molding surface coverings  29  and  80  is as follows: 
     1. Vacuum molding depression/protrusion pull 
     2. Powder slush molding (by freezing pulverization or with microbeads pulverized material) 
     3. Spray molding 
     4. Sol slush molding 
     5. Calender molding 
     6. Extrusion molding 
     7. Inflation molding and the like. 
     Furthermore, surface coverings  29  and  80  can have the following constructions: 
     1. Total instrument panel (used on the entire surface of instrument panel  10 .) 
     2. Partial instrument panel (used on parts of instrument panel  10 .) 
     3. Partial separate instrument panel (used only on airbag lid parts  31 ,  50  and  72  for the passenger seat). 
     By using materials such as those listed above, surface coverings  29  and  80  have relatively high extension percentages at low temperatures. Thus when the airbag deploys, surface coverings  29  and  80  are prevented from scattering. Furthermore, by using materials which have relatively low extension percentages at high temperatures, delays in opening time are prevented. 
     Because a large part of instrument panel  10  on the passenger seat side is sub panel  13 , the overall appearance is enhanced. Furthermore, after airbag lid part  31  opens due to the expansion of the airbag, only sub panel  13  needs to be exchanged. As a result, repair costs are reduced. 
     Because ridge line  11   e  coincides with a front edge of sub panel  13 , sub panel  13  appear as though it is continuous instrument panel body  11 . 
     Central panel  12  includes a center air blowing louver  12   b  and liquid crystal display. The side edges of central panel  12  align with the respective edge of sub panel  13 . This results in a continuous looking instrument panel body that enhances the aesthetics of the vehicle in which it is installed. 
     Airbag unit  18  is supported and stabilized by instrument panel  10 . 
     Airbag lid part  31  is formed from a material that is easily bent and deformed, while the area surrounding airbag lid part  31  is made of a highly rigid material. As a result sub panel  13  looks continuous with instrument panel body  11 , while allowing airbag lid parts  31  to easily open when airbag unit  18  is activated. 
     The description of the embodiments discussed supra refer to an instrument panel located on the passenger&#39;s side of a vehicle having a steering column on the right hand side. Of course, one skilled in the art would understand that the present invention would also work in a vehicle having the driver and passenger sides reversed such as those vehicles intended for use in the United States. 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.