Abstract:
A pressure relief valve ( 10 ) includes a housing ( 20 ) defining an air flow passage ( 34 ). A flap ( 90 ) overlies the air flow passage ( 34 ). At least a portion ( 92, 94 ) of the flap ( 90 ) is movable, in response to an air pressure differential acting on opposite portions of the flap, between an open condition venting air from one side ( 18 ) of the valve ( 10 ) to a closed condition blocking flow of air from a second side ( 19 ) of the valve. The flap ( 90 ) has a plurality of mounting openings ( 104, 106 ). The housing ( 20 ) has a plurality of generally T-shaped mounting posts ( 70, 72 ) projecting from the housing. A snap connection is provided between the flap ( 90 ) and the mounting posts ( 70, 72 ) to secure the flap to the housing ( 20 ) with the mounting posts extending through the openings ( 104, 106 ). The mounting posts ( 70, 72 ) are the only structure holding the flap ( 90 ) on the housing ( 20 ).

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to a vehicle cabin exhauster. In particular, the present invention relates to a flap-type pressure relief valve. 
   2. Description of the Prior Art 
   U.S. Pat. No. 6,357,473 discloses a vehicle cabin exhauster including a vent plate that is fixed in the vehicle and that has vent openings. A movable vent flap is connected with the vent plate. When the air pressure inside the vehicle is less than the outside air pressure, the vent flap is in a closed condition overlying the vent plate and closing the vent openings, to block flow of outside air into the vehicle. When the pressure differential across the vent openings changes so that the air pressure inside the vehicle is greater than the outside air pressure, the vent flap moves to an open condition enabling flow of inside air out of the vehicle. The vent flap may be secured to the vent plate by adhesive, rivets, screws, clips, heat staking, or a separate bracket. 
   It is known to attach a vent flap of the type shown in U.S. Pat. No. 6,357,473 to a vent plate by bending the flap so that the edges of the flap can be fitted under projections on the vent plate. The edges of the flap are received under the projection, to retain the flap on the vent plate. Other portions of the flap fit around other projections on the vent plate to block lateral movement of the flap on the vent plate. The vent flap is made from Mylar. 
   U.S. Pat. No. 5,419,739 discloses a flap-type pressure relief valve. The flap is held onto a frame by a necked-down portion of the flap that extends through an opening in the frame. 
   U.S. Pat. No. 5,601,117 discloses a flap-type pressure relief valve. A pin on a frame extends through a hole in the flap. A retainer bar overlies the flap. The pin is cold-headed after the flap is inserted, to hold the retainer bar, and thereby the flap, in place. 
   In one known embodiment of the invention of U.S. Pat. No. 5,601,117, the flap is made from a thin, flexible rubber material. The pins are T-shaped posts having widened portions that are outside of and hold down the retainer bar. The retainer bar is needed to hold the flap in place on the housing, because the rubber material of the flap can tear off the T-posts. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a pressure relief valve for venting air from a first side of the valve to a second side of the valve and for blocking flow of air from the second side of the valve to the first side of the valve. The valve includes a housing having a base portion defining an air flow passage, and a flap positioned to overlie the air flow passage. At least a portion of the flap is movable relative to the base portion of the housing in response to an air pressure differential acting on opposite portions of the flap. The flap portion is movable between an open condition for venting air from the first side of the valve to the second side of the valve and a closed condition for blocking flow of air from the second side of the valve to the first side of the valve. The flap has a plurality of mounting openings. The housing has a plurality of generally T-shaped mounting posts projecting from the base portion of the housing. The flap has portions adjacent the openings that cooperate with the mounting posts to provide a snap connection between the flap and the mounting posts to secure the flap to the housing with the mounting posts extending through the openings. The mounting posts are the only structure holding the flap on the housing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a portion of a pressure relief valve in accordance with the present invention, shown in an assembled condition mounted in a panel of a vehicle; 
       FIG. 2  is an exploded perspective view of the valve of  FIG. 1 ; 
       FIG. 3  is an enlarged view of a portion of the valve of  FIG. 1 ; 
       FIG. 4  is a sectional view taken generally along line  3 — 3  of  FIG. 1 ; and 
       FIG. 5  is an enlarged view of a portion of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention relates to a vehicle cabin exhauster. In particular, the present invention relates to a flap-type pressure relief valve. As representative of the present invention,  FIGS. 1–5  illustrate a valve  10  constructed in accordance with the invention. 
   The valve  10  is mounted in a vehicle, a portion of which is shown at  12 . The vehicle portion  12  is a portion of a panel defining an opening  14  in which the valve  10  is mounted. The panel  12  may be, for example, a side panel of the vehicle trunk. The panel separates an interior space  16  of the vehicle such as the vehicle trunk, which is to be vented, from the exterior  17  of the vehicle. The valve  10  has an interior side  18  and an exterior side  19 . The valve  10  is operable, as described below, to vent air from the interior  16  of the vehicle to the exterior  17 , while blocking the flow of outside air into the interior of the vehicle. 
   The valve  10  includes a housing  20  and a flap  90 . The housing  20 , in the illustrated embodiment, is made from molded plastic. The housing  20  could be made from other materials, and in a manner other than molding. 
   The housing  20  includes a side wall portion  22  and a base portion  24 . The side wall portion  22  of the housing  20  projects from the base wall portion  24  and extends around the base wall portion. The side wall portion  22  of the housing  20  is mounted on the panel with a seal  26  to secure the valve  10  to the vehicle. 
   The base portion  24  of the housing  20  includes a base wall  30  located inside the side wall portion  22 . The base wall  30  has an upwardly facing (as viewed in  FIG. 2 ) flap engagement surface  32 . 
   The base wall  30  of the housing  20  defines an air flow passage  34  for passage of air from the interior  16  of the vehicle to the exterior  17  of the vehicle. In the particular valve  10  illustrated herein, the air flow passage  34  comprises two identical vent openings  36  and  38  that extend completely through the base wall  30  and through the flap engagement surface  32  of the base wall. The air flow passage  34  could take a different configuration. The vent opening  36  has an upper (as viewed in  FIG. 2 ) end  40  and a lower end (not shown). The vent opening  38  has an upper end  44  and a lower end (not shown). The housing  20  has no through holes, from the interior  16  to the exterior  17 , other than the vent openings  36  and  38 . 
   The base wall  30  includes a separator bar  50  that extends between and separates the two vent openings  36  and  38 . The separator bar  50  has a first end portion or upper end portion  52  located between the upper end  40  of the first vent opening  36  and the upper end  44  of the second vent opening  38 . A second end portion or lower end portion  54  of the separator bar is located between the lower end of the first vent opening  36  and the lower end of the second vent opening  38 . An intermediate portion  56  of the separator bar  50  is disposed between the upper end portion  52  and the lower end portion  54 . 
   The intermediate portion  56  of the separator bar  50  is narrower than the upper and lower end portions  52  and  54 . As a result, each one of the two vent openings  36  and  38  is wider in the middle than at its upper and lower ends. The flap engagement surface  32  of the base wall  30  of the housing  20  has a first radius of curvature about an axis extending generally perpendicular to the length of the separator bar  50 . 
   The base portion  24  of the housing  20  includes two post recesses  60  and  62 . The upper post recess  60  is located in the upper end portion  52  of the separator bar  50 . The lower post recess  62  is located in the lower end portion  54  of the separator bar  50 . The post recesses  60  and  62  are portions of the base wall  30  that are of reduced thickness but that are not openings extending completely through the base wall. The flap engagement surface  32  is discontinuous at the post recesses  60  and  62  because of the reduced material thickness. 
   The base portion  24  of the housing  20  includes two mounting posts  70  and  72 . The mounting posts  70  and  72  are portions of the housing  20  that secure the flap  90  to the housing  20 . The mounting posts  70  and  72  have a generally T-shaped configuration and project from the base portion  24  of the housing  20 , in a direction toward the exterior side  19  of the valve  10 . 
   The upper mounting post, or tee post,  70  projects from the upper post recess  60  in the base portion  24  of the housing  20 . The lower mounting post, or tee post,  72  projects from the lower post recess  62  in the base portion  24  of the housing  20 . The tee posts  70  and  72  project past the flap engagement surface  32 . The tee posts  70  and  72  are identical to each other. 
   Each one of the tee posts  70  and  72  includes a central portion  74  that extends from the post recess to an outer end surface  76  of the post. Two wings or arms  78  project laterally in opposite directions from the central portion  74 . Each one of the wings  78  has an outer surface  80  that faces away from the base wall  30  and extends at an acute angle to the central portion  74 . Each one of the wings  78  also has a flap engagement surface  82 . The flap engagement surfaces  82  on the wings  78  face the level of the flap engagement surface  32  of the base wall  30 , and extend roughly parallel to the flap engagement surface of the base wall. The distance between the flap engagement surfaces  82  on the wings  78  and the flap engagement surface  32  on the base wall  30  is slightly larger than the thickness of the flap  90 , as described below. 
   The flap  90  is a flexible, semi-stiff member made from an airtight material. The preferred material is DuPont Mylar A (registered trademark). This is a flexible synthetic film used as a base for adhesive or pressure sensitive tapes for marking, packaging, or strapping applications; as a base for magnetized sound recording, video, or control tape; as a base for metallic yarn; or as a base for scribing material used in cartography or drafting; and for further manufacture in the industrial arts. 
   The material of the flap  90  is flexible within its elastic range. The material is able to be formed to a preset radius of curvature, and will return to the preformed curve after being bent out of that preformed curve. The material of the flap  90  is also chemical resistant for automotive applications. The thickness of the material ranges from 0.003″ to 0.005″. 
   The flap  90  is formed as one piece and includes two cover portions  92  and  94  that are joined to each other by two hinge portions  96  and  98 . The cover portion  92  is roughly the same shape as, but slightly large in all dimensions than, the vent opening  36 . Similarly, the cover portion  94  is roughly the same shape as, but slightly large in all dimensions than, the vent opening  38 . 
   The upper edge of the flap  90  is indented or cut away at two locations  100  to help define the upper hinge portion  96 . Similarly, the lower edge of the flap  90  is indented or cut away at two locations  102  to help define the lower hinge portion  98 . The hinge portions  96  and  98  are located adjacent and between the cover portions  92  and  94 . The flap  90  also has a long, dog-bone shaped central opening  108  in its center, extending between and partially defining the hinge portions  96  and  98 . 
   The upper hinge portion  96  has a mounting opening or slot  104  extending through the material of the flap  90 . Similarly, the lower hinge portion  98  has a mounting opening or slot  106  extending through the material of the flap  90 . 
   To assemble the valve  10 , the flap  90  is positioned over the housing  20 . The slots  104  and  106  in the flap  90  are positioned over the tee posts  70  and  72 , respectively. The flap  90  is pushed straight down onto the housing  20  and snaps over the tee posts  70  and  72  to connect the flap with the housing. The tee posts  70  and  72  are the only structure holding the flap  90  on the housing  20 . The material of the flap  90 , that surrounds the slots  104  and  106 , deforms outwardly, enlarging the slots. This deformation provides room for the wings  78  of the tee posts  70  and  72  to pass through the slots  104  and  106 . The post recesses  60  and  62  provide space for the hinge portions  96  and  98  of the flap  90  to be pressed downward sufficiently to move under the wings  78  of the tee posts  70  and  72 . After the wings  78  of the tee posts  70  and  72  pass through the slots  104  and  106 , respectively, the material of the flap  90  returns to its original state. 
   When the flap  90  is thus mounted on the housing  20 , the flap engagement surfaces  82  on the tee posts  70  and  72  face the base wall  30  of the housing. The wings  78  on the tee posts  70  and  72  are wider than the slots  104  and  106 . As a result, the flap engagement surfaces  82  on the tee posts  70  and  72  are positioned to engage the flap  90 , press the flap down against the flap engagement surface  32  of the housing  20 , and block removal of the flap from the housing. The flap engagement surfaces  82  on the tee posts  70  and  72  may be spaced slightly from the level of the flap engagement surface  32  to allow for thermal expansion as needed. 
   The flap  90  has a second radius of curvature, about an axis parallel to the axis of curvature of the flap engagement surface  32  of the base wall  30  of the housing  20 . The second radius of curvature, of the flap  90 , is greater than the first radius of curvature, of the flap engagement surface  32  of the base wall  30 . As a result, the cover portions  92  and  94  of the flap  90  are naturally pressed against the flap engagement surface  32  of the housing  20 , covering the vent openings  36  and  38  in the housing wall  30 . The flap  90  is therefore gravity independent and the valve  10  can be mounted at any orientation relative to the vertical. 
   If the air pressure in the vehicle interior space  16  (on the first side  18  of the valve  10 ) is less than the air pressure in the outside space  17  (on the second side  19  of the valve), then the pressure differential keeps the cover portions  92  and  94  of the flap  90  pressed against the flap engagement surface  32  of the housing  20 . This engagement blocks the flow of outside air into the vehicle interior  16 . 
   If the air pressure in the vehicle interior  16  (on the first side  18  of the valve  10 ) becomes greater than the air pressure in the outside space  17  (on the second side  19  of the valve), then the pressure differential causes the cover portions  92  and  94  of the flap  90  to deform and bend at least partially away from the flap engagement surface  32  of the housing  20 . This movement enables the flow of air out of the vehicle interior  16  through the valve  10 . 
   If the pressure differential across the valve  10  becomes even greater, the flap  90  bends at the hinge portions  96  and  98 . The cover portions  92  and  94  of the flap  90  move bodily away from the base wall  24  of the housing  20 . This movement enables an increased rate of flow of air out of the vehicle interior  16  through the valve  10 . 
   When the pressure differential across the valve  10  decreases again, the cover portions  92  and  94  of the flap  90  return to their original condition pressed against the flap engagement surface  32  of the housing  20 . The difference in the radii of curvature of the flap  90  and the flap engagement surface  32  helps to keep the flap pressed tightly against the base wall  30  of the housing  20 . 
   From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.