Abstract:
One or more valves may be employed in a pressure relief vent of a vehicle. The valves may have asymmetrical closing characteristics of differing pressuring inducing closing characteristics or both in order to reduce the peak noise generated as the valves are closing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present application relates generally to a pressure relief vent assembly for use in relieving air pressure in a vehicle. 
         [0002]    Modern automotive vehicles typically include pressure relief vents, mounted somewhere on the body of the vehicle, to selectively allow for air flow out of the passenger compartment of the vehicle while limiting airflow in the opposite direction. The air flow occurs when the air pressure in the vehicle is greater than the atmospheric pressure outside the vehicle by a predetermined amount. For example, the pressure inside the vehicle may rise temporarily when a vehicle door is closed. The pressure relief vents open during these events, thus avoiding air pressure levels that would be uncomfortable for the vehicle occupants. 
         [0003]    The typical body pressure relief vents used on automotive vehicles have uniform and symmetrical flaps and hinges, so they generally open and close simultaneously for given pressure differentials between the vehicle passenger compartment and atmospheric pressure. While adequately relieving the pressure, an issue that sometimes arises with these vents is that the noise generated when all of the flaps slap shut (i.e., impact against a frame of a valve housing) at the same time irritates some vehicle occupants. This may occur, for example, during the vehicle door closing event. The combined noise from all of the flaps may be more easily heard in certain types of vehicles, such as pickup trucks where the pressure relief valve may be located on the back of the cab, allowing this undesirable slapping noise to be more easily heard by the occupants. 
         [0004]    Since there are some occupants who find this noise objectionable, solutions have been proposed that attempt to solve this concern. For example, hot glue dollops have been applied to each flap along its hinge. But this limits the flow rate of air out through the valves more than is desirable and adds more cost to the pressure relief valve assembly than is desired. In another example, nibs have been added to each flap or the frame around the flaps where the two contact. But this allows an increase in backflow through the valves that may be higher than is desirable. Thus, a cost effective way to reduce or eliminate this noise, while still allowing for the body pressure relief function to be performed adequately, is desired. 
       SUMMARY OF THE INVENTION 
       [0005]    An embodiment contemplates a valve for use in a pressure relief vent assembly for a vehicle. The valve may include a valve housing having a frame defining a vent opening; and a flap having a periphery extending around and covering the vent opening, with the periphery including a hinge edge affixed to the frame. The flap includes a hinge adjacent to the hinge edge that is bendable when a pressure in the vehicle is greater than a pressure outside of the vehicle, and an asymmetric closing characteristic, wherein the asymmetric closing characteristic induces a twisting in the flap when the flap opens and closes. 
         [0006]    An embodiment contemplates a pressure relief vent assembly for a vehicle. The pressure relief vent assembly may include a valve housing having a frame defining a first vent opening and a second vent opening. A first flap has a first periphery extending around and covering the first vent opening, with the first periphery including a first hinge edge affixed to the frame, the first flap including a first hinge adjacent to the first hinge edge that is bendable when a pressure differential is greater than a first pressure difference between a pressure in the vehicle and a pressure outside of the vehicle defining a first pressure inducing closing characteristic. A second flap has a second periphery extending around and covering the second vent opening, with the second periphery including a second hinge edge affixed to the frame, the second flap including a second hinge adjacent to the second hinge edge that is bendable when the pressure differential is greater than a second pressure difference between the pressure in the vehicle and the pressure outside of the vehicle defining a second pressure inducing closing characteristic, with the second pressure inducing closing characteristic being different than the first pressure inducing closing characteristic. 
         [0007]    An embodiment contemplates a method for relieving a pressure from inside of a vehicle through a pressure relief vent assembly, the method comprising the steps of: providing a valve, having a frame defining a vent opening covered by a flap having a hinge, to selectively allow for a flow of air from the inside of the vehicle to outside of the vehicle through the vent opening; bending the flap about the hinge to open the vent when the pressure inside the vehicle is greater than a pressure outside of the vehicle by a predetermined amount; and inducing a twisting in the flap as the flap is bent about the hinge such that a periphery of the flap will contact the frame around the vent opening sequentially upon closing. 
         [0008]    An advantage of an embodiment is a reduction in the peak noise level created by the flaps when the valves are closing. This is accomplished with minimal cost, without limiting the air flow through the valves to an undesirably low level, and without increasing the backflow of air through the valves to an undesirable level. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a pressure relief vent assembly according to a first embodiment. 
           [0010]      FIG. 2  is a front view of the assembly of  FIG. 1 . 
           [0011]      FIG. 3  is a view similar to  FIG. 2 , but illustrating a second embodiment. 
           [0012]      FIG. 4  is a front view of a portion of a pressure relief vent assembly according to a third embodiment. 
           [0013]      FIG. 5  is a view similar to  FIG. 4 , but illustrating a fourth embodiment. 
           [0014]      FIG. 6  is a view similar to  FIG. 4 , but illustrating a fifth embodiment. 
           [0015]      FIG. 7  is a view similar to  FIG. 4 , but illustrating a sixth embodiment. 
           [0016]      FIG. 8  is a view similar to  FIG. 4 , but illustrating a seventh embodiment. 
           [0017]      FIG. 9  is a view similar to  FIG. 4 , but illustrating an eighth embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIGS. 1-2  illustrate a pressure relief vent assembly  20  that mounts and seals to an opening  22  in vehicle structure  24 . The assembly  20  includes a valve housing  26 , which has a frame  28 . The frame  28  includes four vent openings  30  that allow for air flow from an interior portion (not shown) of a vehicle, such as a passenger compartment, to outside of the vehicle. 
         [0019]    A set of flaps  32  includes a top flap  34 , an upper middle flap  36 , a lower middle flap  38 , and a bottom flap  40 . Each flap in the set of flaps  32  has a periphery  42 , which includes a hinge edge  44 , an opposed edge  46  that is opposite to the hinge edge  44 , and a pair of side edges  48  that extend between the hinge edge  44  and the opposed edge  46 . The periphery  42  of each flap in the set of flaps  32  contacts with and generally seals around a respective one of the vent openings  30 . Each flap in the set of flaps  32  is secured-over a respective one of the vent openings  30  in the frame  28 —along its hinge edge  44 . Each flap  34 ,  36 ,  38 ,  40  and the portion of the frame  28  defining its corresponding vent opening form a valve  35 ,  37 ,  39 ,  41 . While a vent assembly  20  with four valves is shown herein, of course other numbers of valves can be used for a particular vent assembly, as desired. 
         [0020]    The top flap  34  includes a first hinge  50 , the upper middle flap  36  includes a second hinge  52 , the lower middle flap  38  includes a third hinge  54 , and the bottom flap  40  includes a fourth hinge  56 . Each of the hinges  50 ,  52 ,  54 ,  56  extends adjacent and generally parallel to its respective hinge edge  44 . Each hinge  50 ,  52 ,  54 ,  56 , is bendable to allow its corresponding flap  34 ,  36 ,  38 ,  40  to pivot outward away from the corresponding opening  30  in one direction only—namely, in a direction that allows excess pressure in the passenger compartment to be relieved to atmosphere outside of the vehicle. When the pressures are essentially equal or the higher pressure acts in the opposite direction, the set of flaps  32  remain closed against the frame  28 , greatly limiting or preventing air flow into the vehicle from the atmosphere. The hinges  50 ,  52 ,  54 ,  56  are preferably living hinges (i.e., a thin or soft spot in the material that can repeatedly bend elastically and has a long fatigue life). Alternatively, the hinges may be a mechanical type of hinge connecting each flap to the housing or connecting two portions of each flap together. 
         [0021]    Each of the hinges  50 ,  52 ,  54 ,  56  has a varying width—that is, it is wider at a first end at one side edge  48  than at a second end at the opposite side edge  48 , with a taper in between. This width variation of the hinges  50 ,  52 ,  54 ,  56  creates an asymmetrical closing characteristic, in this case an asymmetrical hinge spring rate. The asymmetrical hinge spring rate means that the hinge spring rate is not constant and uninterrupted from one side edge  48  to the other side edge  48 . That is, when the difference between the pressure in the vehicle relative to atmospheric pressure outside of the vehicle is significant, the flaps will open to allow air to flow out of the passenger compartment. The asymmetrical hinge spring rate, though, will induce a twist in each flap  34 ,  36 ,  38 ,  40  as it opens. When the pressure difference is reduced or eliminated, the flaps will return to their closed positions. As they return to their closed positions, the twisting effect causes the periphery  42  of each flap  34 ,  36 ,  38 ,  40  to contact the frame  28  sequentially rather than simultaneously. This sequential contact may reduce the peak noise generated during flap closing as compared to conventional flaps. And, even though there is twisting induced in the flaps  34 ,  36 ,  38 ,  40  while open, they all seal against the frame  28  when closed. The average width and amount of taper for the hinges  50 ,  52 ,  54 ,  56  can vary based upon the particular vehicle application. 
         [0022]      FIG. 3  illustrates a second embodiment of a pressure relief vent assembly  120 . The embodiment shown in  FIG. 3  has many items in common with the first embodiment and to avoid unnecessary repetition of the description, the same reference numerals have been used but falling within the  1   00 -series. The significant difference with this embodiment resides in the fact that, not only do the hinges  150 ,  152 ,  154 ,  156  taper, but they also vary from one flap  134 ,  136 ,  138 ,  140  to the next. That is, the first hinge  150  may have the same width as the hinges in the first embodiment, while the second hinge  152  on average is slightly wider than the first hinge  150 , the third hinge  154  on average is slightly wider than the second hinge  152 , and the fourth hinge  156  on average is slightly wider than the third hinge  154 . Thus, each hinge will have a hinge spring rate that is different from the other hinges. 
         [0023]    Accordingly, each hinge  150 ,  152 ,  154 ,  156 , and thus each valve  135 ,  137 ,  139 ,  141 , has a differing pressure inducing closing characteristic—they open and close at somewhat different pressure differentials. Consequently, in addition to each flap having its own asymmetrical closing characteristic, the flaps  134 ,  136 ,  138 ,  140  have non-uniform closing characteristics (differing pressure inducing closing characteristic) between them. This may further reduce the peak noise level as compared to the first embodiment in that not only do the flaps  134 ,  136 ,  138 , and  140  contact the frame  128  sequentially around their peripheries  142  during closing, but the flap-to-flap variation will cause each flap, during closing, to contact the frame  128  at a slightly different time than each of the other flaps. While the second embodiment shows this flap-to-flap variation, the other embodiments disclosed herein may also include a flap-to-flap variation as well. 
         [0024]      FIG. 4  illustrates a third embodiment of a pressure relief vent assembly  220 . The embodiment shown in  FIG. 4  has many items in common with the first embodiment and to avoid unnecessary repetition of the description, the same reference numerals have been used but falling within the  200 -series. The significant difference with this embodiment resides in the fact that, the hinges  250 ,  252  (only first and second flaps shown) are now angled (non-parallel) relative to the hinge edge  244  of the flaps  234 ,  236 . The angled hinges  250 ,  252  create the asymmetrical closing characteristic for these valves  235 ,  237 . The width of the hinges  250 ,  252  may be constant as shown in  FIG. 4 , or, if so desired, may include a taper similar to that shown in the first two embodiments to increase the asymmetrical closing characteristic. 
         [0025]      FIG. 5  illustrates a fourth embodiment of a pressure relief vent assembly  320 . The embodiment shown in  FIG. 5  has many items in common with the first embodiment and to avoid unnecessary repetition of the description, the same reference numerals have been used but falling within the  300 -series. The significant difference with this embodiment resides in the fact that the asymmetrical closing characteristic for these valves  335 ,  337  is created by an angled opposed edge  346  rather than by asymmetry built into the hinges  350 ,  352 . The opposed edge  346 , and its corresponding opening  330  in the frame  328 , are angled (i.e., non-parallel) relative to the hinge edge  344  for each flap  334 ,  336  (again only two flaps shown). As with the previous embodiments, the asymmetry in each flap  334 ,  336  causes a twisting during opening and closing of the valves  335 ,  337 , thus causing the periphery  342  of each flap to contact the frame  328  sequentially rather than all at one time. Of course, one may, if so desired, provide asymmetry in the hinges as well. 
         [0026]      FIG. 6  illustrates a fifth embodiment of a pressure relief vent assembly  420 . The embodiment shown in  FIG. 6  has many items in common with the first embodiment and to avoid unnecessary repetition of the description, the same reference numerals have been used but falling within the 400-series. The significant difference with this embodiment resides in the fact that the asymmetrical closing characteristic for these valves  435 ,  437  is created by asymmetrical ribbing  460  protruding from or recessed into the flaps  434 ,  436  (again only two shown) rather than by asymmetry built into the hinges  450 ,  452 . The asymmetry caused by the ribbing  460  causes the twisting leading to the periphery  442  of each flap contacting the frame  428  sequentially. Of course, one may, if so desired, provide asymmetry in the hinges as well. 
         [0027]      FIG. 7  illustrates a sixth embodiment of a pressure relief vent assembly  520 . The embodiment shown in  FIG. 7  has many items in common with the first embodiment and to avoid unnecessary repetition of the description, the same reference numerals have been used but falling within the 500-series. The significant difference with this embodiment resides in the fact that the asymmetrical closing characteristic for these valves  535 ,  537  is created by asymmetrical step cutout features  562  in the flaps  534 ,  536  (only two shown) located between the hinges  550 ,  552  and their respective hinge edges  544 . Again, the asymmetry induces the twisting in the flaps  534 ,  536 . Other types of asymmetry in the flaps disclosed herein may be included in the flaps  534 ,  536  of this embodiment as well, if so desired. 
         [0028]      FIG. 8  illustrates a seventh embodiment of a pressure relief vent assembly  620 . The embodiment shown in  FIG. 8  has many items in common with the first embodiment and to avoid unnecessary repetition of the description, the same reference numerals have been used but falling within the  600 -series. The significant difference with this embodiment resides in the fact that the asymmetrical closing characteristic for these valves  635 ,  637  is created by asymmetrical hinge step features  664  in the flaps  634 ,  636  (only two shown). The hinge step features  664  are created by having one portion of the hinge closer to the hinge edge  644  than another portion. Other types of asymmetry in the flaps disclosed herein may be included in the flaps  634 ,  636  of this embodiment as well, if so desired. 
         [0029]      FIG. 9  illustrates an eighth embodiment of a pressure relief vent assembly  720 . The embodiment shown in  FIG. 9  has many items in common with the first embodiment and to avoid unnecessary repetition of the description, the same reference numerals have been used but falling within the 700-series. The significant difference with this embodiment resides in the fact that the asymmetrical closing characteristic for these valves  735 ,  737  (only two shown) is created by step jogs  766  in opposed edges  746  rather than by asymmetry built into the hinges  750 ,  752 . Each opposed edge  746 , and its corresponding opening  730  in the frame  728 , includes the step jog  766  so that one portion of the opposed edge  746  is closer to the hinge edge  744  than another portion of the opposed edge  746 . As with the previous embodiments, the asymmetry in each flap  734 ,  736  induces a twisting during opening and closing of the valves  735 ,  737 , thus causing the periphery  742  of each flap to contact the frame  728  sequentially rather than all at one time. Of course, one may, if so desired, provide an asymmetry in the hinges  750 ,  752  as well. 
         [0030]    Various alternatives to the embodiments disclosed above are also contemplated. For example, the third through eighth embodiments may include variation between the respective flaps in a vent assembly to create a differing pressure inducing closing characteristic as discussed relative to the second embodiment. In addition, the variation between the respective flaps may include employing flaps from different embodiments discussed above in the same vent assembly. 
         [0031]    While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.