Abstract:
The roof structure of a work vehicle cab is provided with a roof panel having a top surface exposed to the outside and a bottom surface facing the interior of the cab. A sound insulating foam liner is located under the roof panel and secured thereto by adhesives. The bottom surface of the foam liner is provided with ventilating channels. The ventilating channels have two sidewalls and a top wall extending between the sidewalls. A headliner is located below the foam liner and encloses the ventilating channels formed in the foam liner thereby forming ventilating ducts. A headliner mounting structure is also disclosed in which upstanding flanges around the perimeter of the headliner have slots that receive inward extending tabs on the frame to support the headliner.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of application number Ser. No. 09/412,913 file Oct. 5, 1999.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The invention is directed to the headliner of a vehicle and in particular to the mounting structure for the headliner that uses upstanding flanges with slots therein about the perimeter of the headliner, and tabs extending from the vehicle structure through the slots to support the headliner.  
           [0004]    2. Description of the Prior Art  
           [0005]    The operator&#39;s compartment on work vehicles used in construction, agriculture mining and forestry operations is typically provided with a roll over protection system (ROPS). In addition to protecting the operator, the operator&#39;s compartment performs many other functions. The compartment must conform to various standards and regulations for operator noise comfort, visibility and interior size. As such, the operator&#39;s compartment includes sound absorbing materials to reduce noise levels in the compartment. In addition, the operator&#39;s compartment maybe provided with a heating, ventilating and air conditioning system (HVAC) to maintain a comfortable operator work environment. The HVAC system can be mounted in the roof structure of the operator&#39;s compartment. The air is routed through a series of ducts that are usually formed of molded plastic and are provided with additional insulation to reduce heat transfer from and to the air in the duct. The ducts are usually attached to each other, the HVAC unit, to the insulation and the roof structure by various mechanical mechanisms.  
           [0006]    Typically separate components are used for sound absorption and HVAC airflow distribution functions. Sound absorption is accomplished by adhering or mechanically fastening foam sheets to either the roof or bonding them to the headliner.  
           [0007]    Headliners are typically mounted to the frame structure of the operator&#39;s compartment by a number of fasteners. These fasteners can be time consuming to install and are often visible from within the operator&#39;s compartment, detracting from an aesthetically pleasing interior appearance.  
         SUMMARY OF THE INVENTION  
         [0008]    The operator&#39;s cab of a work vehicle is typically provided with a ROPS on which is mounted a roof structure. The roof structure is provided with a roof having a top surface exposed to the outside and a bottom surface facing the interior of the operator&#39;s compartment. A sound insulating foam liner having a top surface and a bottom surface is located under the roof. The top surface of the foam liner is secured to the bottom surface of the roof by adhesives. The bottom surface of the foam liner is provided with ventilating channels. The ventilating channels have two sidewalls and a top wall extending between the sidewalls. A headliner is located below the foam liner. The headliner has a top surface facing the bottom surface of the foam liner and a bottom surface facing the interior of the operator&#39;s compartment. The top surface of the headliner encloses the ventilating channels formed in the foam liner thereby forming ventilating ducts. The top surface of the headliner forming the bottom wall, whereas the foam liner forms the two sidewalls and the top wall of the ventilating duct.  
           [0009]    In another aspect of the invention, the headliner is mounted to the structural frame of the operator&#39;s station by a plurality of upstanding flanges at the perimeter of the headliner with slots therethrough. The slots receive tabs extending inward from the frame. The headliner flanges are deflected inward to install the headliner and once the slots align with the tabs, the flanges return to, or near to, their nominal positions. The headliner has a foam layer that is preferably pressed against the frame to form a tight, attractive fit between the headliner and the frame.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is an exploded perspective view of thew roof structure of an operator&#39;s compartment.  
         [0011]    [0011]FIG. 2 is a perspective view of the roof structure of the operator&#39;s compartment the roof structure being provided with a headliner duct.  
         [0012]    [0012]FIG. 3 is a cross sectional view taken along line  3 - 3  in FIG. 2.  
         [0013]    [0013]FIG. 4 is a cross sectional view of the roof structure without the foam liner which has been eliminated for illustration purposes.  
         [0014]    [0014]FIG. 5 is a perspective view of the upper surface of a headliner.  
         [0015]    [0015]FIG. 6 is a sectional view of the headliner of FIG. 5 mounted to the structural frame of the operator&#39;s compartment.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    [0016]FIG. 1 illustrates the roof structure  10  of an operator&#39;s compartment for a work vehicle. The operator&#39;s compartment is defined by six vertically extending posts  12 . Four of the posts  12  are tubular members that extend into horizontally extending members  14  forming the ROPS for the compartment. Two flanges  16  extend between two pairs of ROPS posts  12  downwardly from the corresponding horizontal extending members  14 . The openings between the ROPS posts are provided with windows  17  (only shown in FIG. 3) and doors (not shown). A HVAC compartment  18  is located to the rear of the operator&#39;s compartment and is designed to hold a HVAC unit, not shown.  
         [0017]    The operator&#39;s compartment is provided with a roof structure having three main components, a roof  20 , a rigid sound insulating foam liner  22 , and a headliner  24 . In the preferred embodiment the roof is formed of sheet metal and is welded to the steel horizontally extending  14  members of the ROPS. The roof  20  also extends over the HVAC compartment  18  and is provided with drip channels  26 . The roof has a top surface  28  facing the outside and a bottom surface  30  facing the interior of the operator&#39;s compartment.  
         [0018]    The sound insulating foam liner  22  is located below the roof  20  and is formed from a polyurethane expanding foam or some similar material. The foam liner is manufactured or molded to fill the cavity formed below the roof with sound absorbing material. The foam liner could be a single part or be made up of several parts. A central forward section  31  is left open to accommodate HVAC controls and/or a radio in the roof structure. The top surface  32  of the foam liner  22  is fixed to the bottom surface  30  of the roof by adhesives. In addition, the expansion of the foam and adhesives secure the foam liner  22  to the flanges  16 . The bottom surface  34  of the foam liner is provided with ventilating channels  36  having sidewalls  38  and top walls  40 . These ventilating channels  36  can be placed and sized for proper air velocity and distribution. In addition, the foam reduces the airflow noise level of the HVAC system as air is moving through the ventilating channels  36 .  
         [0019]    Located immediately below the foam liner  22  is the headliner  24 . The headliner is porous so that noise form the interior of the operator&#39;s compartment can be deadened by the foam liner. The headliner  24  comprises two pieces a front half  41  and a back half  43 . The headliner has a top surface  42  facing the foam liner  22  and a bottom surface  44  facing the interior of the operator&#39;s compartment. The headliner  24  cooperates with the ventilating channels  36  formed in the foam liner  22  to form ventilating ducts. The headliner  24  enclosing the ventilating channels  36  by forming the bottom wall. To better seal the ventilating ducts the foam liner may be provided with molded in raised edges to increase its sealing effect when the foam liner is compressed into place. The headliner is provided with louvered vents  46  that are in pneumatic communication with the ventilating ducts to direct air into and from the interior of the operator&#39;s compartment.  
         [0020]    The side edges  47  of the back half  43  of the headliner  24  rests on the top edges of windows  17  as seen in FIG. 3. The front half  41  of the headliner  24  is provided with side slots  48  and tabs  50  for supporting the headliner. The side slots  48  engages tabs  52  mounted to the horizontal members of the ROPS as shown in FIG. 4. Whereas tabs  50  are inserted into apertures formed in the ROPS also shown in FIG. 4. It should be noted that the foam liner has not been illustrated in FIG. 4 to better illustrate the headliner mounting structure.  
         [0021]    The headliner&#39;s primary function is noise reduction and it is constructed of a conventional porous material to let sound from the interior of the operator&#39;s compartment pass through to the sound absorbing foam liner where the sound is absorbed. This reduces operator&#39;s compartment noise level. The headliner&#39;s secondary function is to be the bottom wall of the ventilating ducts for the HVAC system, and retain the adjustable or fixed louvers for operator controlled or directed airflow.  
         [0022]    An alternative embodiment of the headliner is shown in FIG. 5 and designated generally as  124 . The headliner  124  is mounted to the frame structure using flanges with slots that receive tabs similar to the slots  48  and tabs  52  described above and shown in FIG. 4. The headliner  124  is formed with an upstanding rib  60  about the perimeter of the headliner. The rib  60  extends substantially about the entire perimeter but may have some interruptions. The rib  60  increases the bending strength of the headliner. At periodic locations about the perimeter of the headliner, upstanding flanges  62  are provided that extend above the rib  60 . The upstanding flanges  62  extend upward and slightly outward at an angle of five to ten degrees from vertical. The flanges  62  each have an opening therethrough such a slot  68 .  
         [0023]    The headliner  124  is mounted to the horizontal members  64  of the operator&#39;s compartment structural frame as shown in FIG. 6. In this case, the structural frame is a roll over protective structure (ROPS). The horizontal members  64  are metal tubes with tabs  66  attached thereto by welding or by other fasteners. The tabs  66  extend inward from the horizontal members  64 . The headliner is installed in the operator&#39;s compartment by deflecting the flanges  62  inward so that the upper end of each flange passes over the distal end of the respective tab  66 . Once the tab  66  is aligned with the slot  68  in the flange  62 , the flange  62  will return to, or near to, its nominal position.  
         [0024]    The headliner  124  is of a laminate structure having a plastic substrate  76  of ABS, styrene or similar material. The substrate  76  is perforated to permit sound from the interior of the operator&#39;s compartment to pass through the headliner and into the foam liner  22  as described above. A layer of open cell foam  78  is bonded to the lower surface of the substrate  76  by an adhesive in a roll coating process. An interior cover  80  is applied to the inner surface of the foam  78  through a flame bonding process. The cover  80  can be a non-woven or woven fabric, perforated vinyl or leather etc.  
         [0025]    Once the laminate structure is formed and cut to length in a sheet, it is heated and vacuum formed to the desired shape. After forming, various openings and cut outs are made by water jet trim. The vacuum forming process, which turns up the rib  60  and flanges  62 , creates a living hinge where the substrate is bent upward. The hinge provides resiliency to the substrate to enable the flanges  62  to flex inward to install the headliner. Once the tabs  66  are aligned with the slots  68 , the flanges will return toward the nominal position but may not fully return there due to the presence of the structural frame horizontal members  64 . This results in the foam layer  78  being partially compressed and the formation of a tight or snug fit between the headliner and the upper horizontal members  64  of the frame. The result is a pleasing appearance to the interior appearance of the operator&#39;s compartment without any visible fasteners for the headliner. Furthermore, it is easier and faster to install the headliner.  
         [0026]    The headliner  124  has openings  70 ,  72  for ventilation grills, radio or HVAC control panels, etc. In the embodiment shown, the headliner  124  has a flat portion  74  along the front. The flat portion  74  rests beneath the horizontal member  64  of the ROPS at the front of the operator&#39;s compartment. The structural strength provided to the headliner by the molded plastic substrate and the rib  60  allows the headliner to span across the front of the operator&#39;s compartment without additional attachments to the structural frame at that the front. Alternatively, various interior components, such as a sun visor and/or rear view mirror can be bolted through the headliner into the frame along the front, which would provide additional attachment of the headliner to the frame structure.  
         [0027]    The headliner  124  can be used as described above to complete air ducts in the roof. Alternatively, the headliner  124  can be used in applications where it is not used to form air ducts.  
         [0028]    The invention should not be limited by the above described embodiment, but should be limited solely by the claims that follow. For example, the openings through the flanges  62  may be round holes fitted over inwardly extending pins on the frame.