Patent Publication Number: US-2017355107-A1

Title: Methods for making inflatable interior panel arrangements for motor vehicles

Description:
TECHNICAL FIELD 
     The technical field relates generally to interior panels for motor vehicles, and more particularly, the technical field relates to methods for making inflatable interior panel arrangements, such as inflatable knee bolsters or the like, for motor vehicles. 
     BACKGROUND 
     Automobile manufactures prioritize the development and incorporation of safety systems into motor vehicles to help protect occupants during various types of collisions. The seatbelt, which helps to keep occupants secured within their seats, continues to be the primary safety device used in the automotive industry. 
     Additional safety devices, and in particular inflatable occupant restraint systems or airbag systems are known to enhance the effectiveness of seatbelts in protecting a vehicle occupant during a protection. The traditional frontal airbag is disposed in the steering wheel or the instrument panel of the motor vehicle and acts to protect the head, chest, and pelvic area of a front occupant during a sudden deceleration caused, for example, by an accident. During such an event, however, the lower torso of the occupant may slide forward on the seat of the vehicle especially if a seatbelt is not wom by the occupant. It is known to provide a restraint device, which is commonly referred to as a “knee blocker” or “knee bolster,” to limit this type of movement. 
     In one knee bolster device described in U.S. Pat. No. 6,302,437 issued to Marriott, an interior vehicle outer panel is operatively coupled to an airbag that is inflatable by a gas source (e.g., gas inflator). During inflation of the airbag, the outer panel is directed towards the lower extremities of an occupant to aid in limiting lower torso translation forward along the vehicle seat. The knee bolster device may be formed, for example, by injection molding the outer panel. The airbag is then coupled to the outer panel during a secondary fastening and/or joining operation(s) by mechanical means. Unfortunately, such secondary fastening and/or joining operations, which can include, for example, additional parts, such as fasteners, brackets, and the like, as well as additional labor, robots, and/or fixtures for forming the device after injection molding or otherwise after forming the outer panel, are relatively expensive and can include significant investment and/or operating costs. 
     Commonly assigned U.S. patent application Ser. No. 14/920,215 filed Oct. 22, 2015; Attorney Docket No. 109-0030: entitled “Methods for Making Inflatable Interior Panel Arrangements For Motor Vehicles”, the disclosure of which is hereby expressly incorporated herein for all purposes, describes methods of making inflatable interior panels that provide an inflatable bladder section and an outer panel section that are integrally coupled to the inflatable bladder section and that have a panel portion stiffness greater than a bladder portion stiffness of the inflatable bladder section. 
     Accordingly, it is desirable to provide methods for making inflatable interior vehicle panel devices for motor vehicles with improved manufacturing efficiencies and/or lower manufacturing costs. Furthermore, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     BRIEF SUMMARY 
     Methods for making inflatable interior panel arrangements for motor vehicles are provided herein. In accordance with an exemplary embodiment, a method for making inflatable interior panel arrangement for a motor vehicle includes, but is not limited to, introducing a molding material into a molding tool that has tooling surfaces. The molding material is first deposited over a tooling surface associated with a first portion of the molding tool controlled to a first tooling surface temperature while remaining tooling surfaces are maintained at a second tooling surface temperature, different than the first tooling surface temperature. The molding tool is advanced to a closed configuration such that the tooling surfaces define a substantially enclosed cavity in the molding tool. An inflatable interior panel is formed comprising rotating the molding tool to cover the tooling surfaces of the substantially enclosed cavity with the molding material. The inflatable interior panel comprises an inflatable bladder section and an outer panel section that is integrally coupled to the inflatable bladder section and that has a panel portion stiffness greater than a bladder portion stiffness of the inflatable bladder section. 
     In a second exemplary embodiment, and a method for making inflatable interior panel arrangement for a motor vehicle includes, but is not limited to, preparing a molding tool having a first tooling surface and a second tooling surface so that the first tooling surface is at a temperature different than a temperature of the second tooling surface. The method further includes, but is not limited to, introducing a molding material into the molding tool. The method further includes, but is not limited to, advancing the molding tool to a closed configuration such that the tooling surfaces define a substantially enclosed cavity in the molding tool. The method still further includes, but is not limited to, forming an inflatable interior panel by rotating the molding tool to cover the tooling surfaces of the substantially enclosed cavity with the molding material. An outer panel section is formed on the first tooling surface and an inflatable bladder portion is formed on the second tooling surface and the outer panel section has a stiffness greater than a bladder portion stiffness and the outer panel section is integrally coupled to the inflatable bladder section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIGS. 1-6  illustrate, in cross-sectional views, methods for making inflatable interior panel arrangements during various fabrication stages in accordance with an exemplary embodiment. 
         FIG. 7  illustrates an inflatable interior panel in accordance with herein described embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The The following Detailed Description is merely exemplary in nature and is not intended to limit the various embodiments or the application and uses thereof. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
     Various embodiments contemplated herein relate to methods for making inflatable interior panel arrangements for motor vehicles. The exemplary embodiments taught herein introduce molding material into a molding tool that has tooling surfaces. In an exemplary embodiment, the molding material is first deposited over a tooling surface associated with a first portion of the molding tool controlled to a first tooling surface temperature while remaining tooling surfaces are maintained at a second tooling surface temperature, different than the first tooling surface temperature. 
     The molding tool is advanced to a closed configuration such that the tooling surfaces define a substantially enclosed cavity in the molding tool. In one example, the molding tool includes the first portion and a second portion that are matched mold portions and that are advanced towards each other to the closed configuration. In the closed configuration, the tooling surfaces associated with each of the first and second portions together defined the substantially enclosed cavity. In an exemplary embodiment, the molding tool is part of a rotational molding process and is rotated in the closed configuration to move at least a portion of the second molding material over the tooling surfaces associated with the second portion of the molding tool while at least a portion of the first molding material remains over the tooling surfaces associated with the first portion of the molding tool. As such, the tooling surfaces of the substantially enclosed cavity are cooperatively covered with the molding material. 
     In an exemplary embodiment, the molding material is a slush phase, but alternatively may be liquid phase, powered phase and/or molten before introduction into the molding tool. Still further alternatively, the molding material may be multi-component including, for example, a first molding material and a second molding material. In such case, the first molding material and the second molding material are, independently, in a slush phase, a powdered phase, a liquid phase and/or a molten condition or combinations thereof before and/or during rotation of the molding tool to facilitate covering the tooling surfaces of the substantially enclosed cavity. 
     In accordance with an exemplary embodiment, the first tooling surface is maintained to a first tooling surface temperature such that a portion of the molding material upon deposition on the first tooling surface is at least partially solidified to form a first solidified molded material prior to further processing. The first molded material and the remaining molding material is subsequently solidified to form a complete inflatable interior panel corresponding to the shape of the substantially enclosed cavity. 
     In an exemplary embodiment, the inflatable interior panel includes an outer panel section that comprises the first solidified molded material and an inflatable bladder section that comprises the remaining solidified molded material. The outer panel section is integrally coupled to the inflatable bladder section and is stiffer than the inflatable bladder section. Advantageously, in an exemplary embodiment, the relatively more flexible (i.e., less stiff) inflatable bladder section allows the bladder section to be effectively inflated by, for example, a gas inflator, to move the relatively more rigid (i.e., more stiff) outer panel section towards the lower extremities of a vehicle occupant during a crash event to aid in limiting lower torso translation of the occupant forward along the vehicle seat. Moreover, advantageously, in an exemplary embodiment, by forming both the outer panel section and the inflatable bladder section together during the same rotational molding process, the outer panel section and the inflatable bladder section can be coupled together without requiring any secondary joining and/or fastening operations to thereby improve manufacturing efficiencies and/or lower manufacturing costs. 
       FIG. 1  is a sectional view of a molding tool  10  used in a rotational molding process (discussed in further detail below) for fabricating an inflatable interior panel  12  (shown in  FIG. 6 ) of an inflatable interior panel arrangement  13  (shown in  FIG. 7 ) in accordance with an exemplary embodiment. The molding tool  10  includes molding tool portions  14  and  16  that may be moved relative to each other during the rotational molding process as is well-known in the art. The molding tool portions  14  and  16  are a match die set each having first tooling surface  18  and second tooling surface  20 . The tooling surfaces  18  and  20  are accessible when the molding tool  10  is in an open configuration  22  (i.e., the molding tool portions  14  and  16  are spaced apart) as illustrated in  FIG. 1 , and define a substantially enclosed cavity  24  when the molding tool  10  is in a closed configuration  26  (i.e., the molding tool portions  14  and  16  are positioned in contact with each other) as illustrated in  FIG. 3 . 
     Within the tool portion  14  and adjacent the first tooling surface  18 , the tool portion  14  is formed with a temperature shell  15 . The temperature shell  15  may include a fluid circuit or a portion(s) of a fluid circuit (not shown) that contains a heat transfer fluid (e.g., water, air, oil, or the like) and that is in fluid communication with a heating and/or cooling device (e.g., thermolator, heat exchanger, or the like) for regulating the temperature of the first tooling surface  18 . In exemplary embodiments, the first tooling surface  18  may be cooled relative to second tooling surface  20  to be at a predetermined temperature less than the temperature of the second tooling surface  20 . In other exemplary embodiments, the first tooling surface may be heated relative to the second tooling surface  20  to be at a predetermined temperature greater than the temperature of the second tooling surface  20 . The temperature of the first tooling surface less than or greater than the second tooling is selected in exemplary embodiments based upon the molding material. 
     In further exemplary embodiments, the entire molding tool  10  is configured to be heated and/or cooled as part of the rotational molding process to maintain the second tooling surfaces  20  at a temperature different than the temperature of the first tooling surface  18 , which is maintained by temperature shell  15 . For example, the molding tool portions  14  and  16  may independently include a fluid circuit or a portion(s) of a fluid circuit (not shown) that contains a heat transfer fluid (e.g., water, air, oil, or the like) and that is in fluid communication with a heating and/or cooling device (e.g., thermolator, heat exchanger, or the like) for regulating the temperature of the molding tool portions  14  and  16 . 
     Referring to  FIG. 2 , molding material  28  is introduced to the molding tool  10  and onto the first tooling surface  18 . Nonlimiting examples of materials suitable for the molding material  28  include polyurethanes, polyurethane prepolymers, thermoplastic polyurethanes (TPU), thermoplastic polyolefins (TPO), polypropylene, epoxies, epoxy urethane blends, combinations thereof, and the like. In an exemplary embodiment, the molding material  28  includes a curable polymeric precursor such as a polyester polyol(s), polyether polyol(s), or the like and a hardener such as an isocyanate (e.g., block or unblock isocyanate(s)). In an exemplary embodiment, the molding material  28  is deposited overlying the first tooling surface  18  of the molding tool portion  14  in a slush form. Advantageously, in an exemplary embodiment, applying the molding material  28  in slush form onto the first tooling surface  18  facilitates a portion (not depicted) of the molding material  28  spatially conforming to match the first tooling surface  18  and solidifying into the first solidified molded material  32 . Alternatively, the molding material  28  may be deposited overlying the first tooling surface  18  of the molding tool portion  14  in a liquid phase, a solid phase or powder form. 
     Referring to  FIG. 3 , the molding tool portions  14  and  16  are advanced towards each other to the closed configuration  26  and the tooling surfaces  18  and  20  together define the substantially enclosed cavity  24 . The process continues as illustrated in  FIGS. 4-5  by rotating the molding tool  10  as part of the rotational molding process to move at least a second portion of the molding material  28  onto and/or over the tooling surfaces  20  of the molding tool portion  16  forming a second solidified molded material  34 . In an exemplary embodiment, at least the portion of the molding material  28  (e.g., either in the molten condition or cured solid form as first solidified molded material  32 ) that has formed the first solidified molded material  32  remains on and/or over the tooling surfaces  18  of the molding tool portion  14 . As such, the tooling surfaces  18  and  20  are substantially completely covered by the molding material  28  solidified as first solidified molded material  32  and second solidified molded material  34 . 
     Further and as discussed above, the mold tooling portions  14  and  16  may be configured for heating and/or cooling, while the shell  15  is configured to maintain the first tooling surface  18  to a predetermined temperature relative to the remainder of the tooling portions  14  and  16  and/or the second tooling surfaces  20 . In an exemplary embodiment, the the molding tool portions  14  and  16  are heated to a temperature of from about 100 to about 200° C. during the initial stages of rotating the molding tool  10 , while the shell  15  maintains the first tooling surface from 10 to about 50° C. cooler than second tooling surface  20 . In an exemplary embodiment, the molding material  28  is a TPO in slush form and, upon contact with the first tooling surfaces  18 , conforms to the first tooling surface  18  and a portion thereof solidifies. Next, during the latter stages of rotating the molding tool  10 , the molding tool portions  14  and  16  may be cooled to help solidify the molding material  28  to thereby form the inflatable interior panel  36 . In an exemplary embodiment, the molding tool portions  14  and  16  are cooled to a temperature of from about 20 to about 80° C. Alternatively, in the embodiment in which the molding material  28  is a thermosetting material, the molding material  28  may be in a liquid form during the initial stages of rotating the molding tool  10 . As such, when the molding material  28  contacts the heated tooling surfaces  18  and  20 , a first portion the molding material  28  cures and solidifies to form the inflatable interior panel  12 . Optionally, in this embodiment, during the latter stages of rotating the molding tool  10 , the molding tool portions  14  and  16  may be cooled as discussed above. 
     As illustrated in  FIG. 5 , the first solidified molded materials  32  and  34  are molded to a shape corresponding to the tooling surfaces  18  and  20  of the substantially enclosed cavity  24  and define the inflatable interior panel  12 . In particular, the inflatable panel  12  includes an inflatable bladder section  38 , which has a shape that corresponds to the tooling surfaces  20 , and an outer panel section  40 , which has a shape that corresponds to the tooling surfaces  18  and that is integrally coupled to the inflatable bladder section  38 . In an exemplary embodiment, the solidified molded material  32  forms the outer panel section  40 , which is relatively stiff or rigid (e.g., relatively high flexural modulus), and the solidified molded material  36  forms the inflatable bladder section  38 , which is relatively flexible (e.g., relatively low flexural modulus) and having for example a relatively high elongation. As such, the outer panel section  40  has a panel portion stiffness greater than a bladder portion stiffness of the inflatable bladder section  38 . In an exemplary embodiment, the solidified molded material  32  has a flexural modulus of from about 800 to about 1300 MPa or greater than about 1300 MPa at 23° C., and the solidified molded material  34  has a flexural modulus of from about 1 to about 500 MPa and an ultimate elongation of from about 25% to about 500% at 23° C. 
     The process continues as illustrated in  FIG. 6  by advancing the molding tool portions  14  and  16  away from each other to the open configuration  22  to open the substantially enclosed cavity  24  for removing the inflatable interior panel  12  from the molding tool  10 . Referring to  FIG. 7 , an opening  42  is formed in the inflatable bladder section  38  by removing a portion  44  of the inflatable bladder section  38 . Next, an inflator  46  is operatively coupled to the inflatable bladder section  38  about the opening  42  to form the inflatable interior panel arrangement  13 . In an exemplary embodiment, the portion  44  is removed from the inflatable bladder section  38  using a die cutting operation or the like and the inflator  46  is operatively coupled to the inflatable bladder section using a welding operation. In an exemplary embodiment, the inflator  46  is configured to generate gas to inflate the inflatable bladder section  38  to advantageously move the outer panel section  40  towards the lower extremities of a vehicle occupant during a crash event to aid in limiting lower torso translation of the occupant forward along the vehicle seat. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description of the disclosure, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the disclosure. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the disclosure as set forth in the appended claims.