Abstract:
The present invention provides a two-way vent for a vehicle that opens in a front and rear direction and includes a preferably symmetric cam having an apex on its centerline, and first and second convex sides each terminating respectively in a recess at the base of the cam. The degree of opening of the vent is determined by the displacement of a follower rod with respect to the apex of the cam. From its originally closed position with the follower positioned at the apex, the vent can be opened either forward or backward by selectively moving a handle that actuates the follower along the curved paths defined by the convex sides. The cam preferably includes a lateral cusp at the end of each curved path, the cusp defining a transition from the curved path to the recess.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to ventilators, and more particularly to a manually actuated two-way vehicle ventilator having a cam and follower assembly adapted to limit the opening of the vent. 
     2. Description of the Prior Art: 
     Two-way hingeless ventilators of the present type are well known by those of skill in the art, and the operation thereof is described in detail in U.S. patents, particularly U.S. Pat. No. 6,280,315, U.S. Pat. No. 5,766,068, U.S. Pat. No. 4,452,129, and U.S. Pat. No. 3,839,950, the disclosures of which are incorporated herein by reference. In certain vehicles it is desirable to introduce ventilation through a manually actuated dedicated vent located in a roof or sidewall of the vehicle. These vents open both toward and away from the oncoming flow of air when the vehicle is in motion to introduce and expel air, respectively. The vent may open in stages determined by rest positions along a cam or track that cooperates with guide ends of a tensioning rod to set the position of the vent. The guide ends are biased against the cam or inside the track by the tensioning rod&#39;s cooperation with guide arms mounted on the cover or lid. With detents at intermittent locations on the cam, the vent provides some options for selecting the degree of opening of the vent. However, a by-product of existing cams such as the generally triangular cams is that the vent continues to open at a generally constant rate as the guide ends travel along the cam from the closed to the fully open position. Moreover, there is not a stable and secure receiving recess on the cam surface to ensure that the guide end does not inadvertently move on the cam. 
     It has been determined by the present inventor that the prior art vents open too wide in some instances, causing a hazard when the vents are disposed on the side of the vehicles. Namely, the vents when open can catch on objects and damage both the vehicle and surrounding objects, or the vent could injure a person standing by the vehicle. Thus, the art would benefit from a vent design that would limit the opening of the vent in comparison with the existing vents. 
     SUMMARY OF THE INVENTION 
     The present invention provides a two-way vent that comprises a pivoting lid that cooperates with an opening in a frame to selectively open and close the vent. A handle is mounted to the pivoting lid through a connected tensioning rod that rides on a pair of preferably symmetric cams at a pair of rollers on each end. Actuation of the handle causes the lid to pivot about the frame at a forward or rear edge as the rollers travel along the cams&#39; surfaces. To control the degree of pivoting of the lid, and hence the degree of opening of the vent, the cam surface is selected to have a shape generally comprising an apex on its centerline, and first and second convex sides each terminating respectively in a recess adjacent the base of the cam. The first and second cam surfaces preferably includes a lateral cusp defining a transition from the convex surface to the recess. The recesses provide a stable position for the rollers that makes it unlikely that the roller can be inadvertently displaced due to wind gusts or vibration. Moreover, the degree of opening of the vent as the rollers ride the cam surfaces of the present invention is reduced by the narrowing and shortening of the cam. In a preferred embodiment the convex sides of the cam are circular in profile, and the recesses are circular in profile. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The exact nature of this invention, as well as its objects and advantages, will become readily apparent to one of skill in the art upon reference to the following detailed description when considered in conjunction with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof, and wherein: 
     FIG. 1 is an lower perspective view of a first preferred embodiment of the present invention; 
     FIG. 2 is a front view of the first preferred embodiment of FIG. 1; 
     FIG. 3 is a bottom view of the first preferred embodiment of FIG. 1; 
     FIG. 4 is a side view of the first preferred embodiment of FIG. 1 in a closed position; 
     FIG. 5 is a side view of the first preferred embodiment of FIG. 1 in an open position; and 
     FIG. 6 is a lower perspective view of the cam and spacer of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description is provided to enable any person of ordinary skill in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the general principles of the present invention have been defined herein specifically to provide a vehicle vent with a reduced opening mechanism. 
     FIGS. 1 through 5 illustrate a first preferred embodiment of the present invention. A vent generally denoted  100  comprises generally a handle  120 , a base plate  140 , a lid  160 , and a cam  180  and follower  190  for setting the degree of vent openness. The handle  120  is an elongate bar that has a cylindrical middle section  102  positioned for gripping. The cylindrical middle section  102  transitions to first and second end sections  104  that gradually taper from the cylindrical profile at the juncture with the middle section to a flattened profile at the ends  106 . Each end  106  of the handle  120  terminates in a bracket  108  oriented generally perpendicular to the longitudinal axis of the handle  120  and parallel to each other, such that the handle  120  and the brackets  108  have a U-shaped profile with an elongate base and short sides. Each bracket  108  includes an elongate hole  110  aligned for receiving a tensioning rod  112  therein where the tensioning rod  112  spans the length of the handle  120  and projects longitudinally outward through each hole  110  in the handle&#39;s brackets  108 . The ends of the tensioning rod  112  that projects through each bracket  108  of the handle  120  are enclosed by an annular roller  114  with an integral annular collar  116  of a larger diameter than the elongate hole  110  of the handle&#39;s bracket  108 . The collar  116  is fixed on the tensioning rod  112  and adjacent to the handle  120  such that the collar  116  secures the tensioning rod  112  in the brackets  108  of the handle  120  between the two elongate holes  110 . The roller  114  extends axially outward from the collar  116  and functions as a follower  190  for the cam  180  as explained in greater detail below. To locate the tensioning rod  112  in the brackets  108  of the handle  120  with the collars  116 , the rod  112  may be comprised of two halves  112   a,b  that each have a collar  116  on one end and join together at the other end in a locking relationship. Each half  112   a,b  of the rod  112  is inserted into the handle bracket  108  with the collar  116  just outside of the bracket  108 , and joined together at the other end in a locked arrangement. 
     The tensioning rod  112  passing through the brackets  108  on the handle  120  additionally pass through elongate holes  122  in a pair of side supports  124  and a middle support  126 . The side supports  124  and middle support  126  comprise bell-shaped metal plates oriented parallel to one another and rigidly mounted at a first end  128  to the lid  160 . The connection to the lid  160  can be accomplished by providing a first end  128  of each support perpendicular to the main portion of the support to achieve an L-shaped configuration, and fastening, welding, or otherwise adhering the first surface  128  with the adjoining surface of the lid  160 . The contour of the supports&#39; sides are preferably convex along a bottom portion adjacent to the lid  160  to accommodate the rotational movement of the side supports  124  and middle support  126  through respective slots  130  on the base plate  140  as described in more detail below. The upper portion of each of the supports includes an elongate hole  122  equally spaced from the bottom of the support and aligned to be co-linear with each other. The elongate holes  122  of the supports mount the tensioning rod  112  that passes through the handle brackets  108 , thereby linking the handle  120 , supports  124 , 126  and lid  160  in a fixed relationship. That is, the handle  120 , supports  124 , 126 , and lid  160  move and pivot as a single rigid structure. 
     The lid  160  comprises a generally rectangular plate  162  with a rim  164  extending around a perimeter. The interior of the lid  160  may preferably include a padding (not shown) on the inner face to dampen any noise generated by contact of the lid  160  with the base plate  140 . The padding will include cut-away portions where the side and middle supports  124 , 126  contact the lid  160 . 
     The base plate  140  generally comprises a base flange  142  oriented in a first plane with a plurality of spaced apart apertures  144  around the perimeter for mounting the base plate  140  to a top or side surface of the vehicle (not shown). The base flange  142  is preferably rectangular in nature with rounded corners  146  at the external edge junctures. At the interior of the base flange  142  includes a raised rectangular grating  148 . A shoulder  150  extending along a rectangular perimeter of the grating  148  separates the grating  148  from the base flange  142  and defines the height of the raised grating  148 . The shoulder  150  of the base flange  142  is sized to coincide with the rim  164  of the lid  160  such that the rectangular lid  160  fits over the raised rectangular grating  148  of the base plate  140  when the vent  100  is closed. The grating  148  comprises an array of closely spaced holes  152  for allowing air to pass through but prevents any debris from entering the vehicle. The raised grating  148  further includes three elongate slots  130  extending generally its width at a middle section and at each end thereof. The three elongate slots  130  are aligned to coincide with, and receive therein the respective middle  126  and side supports  124 . 
     Mounted on the opposite ends of the base flange  142  of the base plate  140  are a pair of cams  180 . As shown in FIG. 6, each cam  180  is preferably integrally formed with a spacer  182  comprised generally of an elongate rectangular bar with a pair of holes  184  therein to secure the cam  180  to the base plate  140  via fasteners (not shown). Fasteners pass through the holes  184  in the spacer  182  and the base flange  142  of the base plate  140  to fix the cam  180  in the designated position. The cam  180  comprises a projection that is preferably symmetric with respect to a vertical axis and includes an apex  186  at the centerline of the symmetry with a slight indentation  188  at the apex  186  for resting a cylindrical follower  190  thereon. The cam  180  includes a pair of convex sides surfaces  181  connecting the apex  186  with a pair of recesses  183  at the base  185  of the cam  180 . The convex surfaces  181  in a preferred embodiment are circular with a radius larger that the height of the cam  180  above the spacer  182 , to provide a smooth path for a follower  190  from the apex  186  to a recess  183 . At the base  185  of the cam  180  on each side is a recess  183  sized to receive the follower  190  therein. The transition from the convex side surfaces  181  to the recesses  183  results in a pair of lateral cusps  187  that form a local farthest point from the centerline of symmetry. Like the indentation  188  at the apex  186 , the recesses  183  provide a stable resting position for the follower  190 , and an increased force on the handle is required to displace the follower from the recesses. The placement of the follower  190  within the recesses  183  defines the open position for the vent  100 . 
     Adjacent to the recesses are short, curved segments  191 , extending along the curved path defined by the curved side surfaces  181 , that connect the recesses with the spacer  182 . The juncture between the recesses  183  and the curved segments  191  form a second pair of lateral cusps  193 , that may extend laterally just beyond the extent of the first pair of lateral cusps  187 . The distance between the spacer  182  and the lateral cusps  193  is preferably less than the height of the spacer  182  and is set to preferably have the follower  190  rest against the spacer  182  while located in the recess  183 . The first pair of lateral cusps  187  are approximately in the middle of the cam  180 , such that the distance between the spacer  182  and the lateral cusps  187  is approximately equal to the distance between the lateral cusps  187  and the apex  188 . 
     The cooperation of the various components will now be described. The base plate  140  is mounted over a pre-established port or opening in the vehicle such that the grating  148  permits ventilation to the vehicle&#39;s interior. In the closed position (see FIG.  4 ), the handle  120  depends perpendicular to the base plate  140  and the tensioning rod  112  passing through the handle  120  is positioned at the apex  186  of the each cams  180  at the annular rollers  114 . The position and height of the cam  180  is partially determined by the height of the spacer  182  and preferably locates the tensioning rod  112  at a maximum distance from the base plate  140 , placing the supports  124 , 126  in tension and forcing the follower  190  on the cam  180 . The relative angular position α of the lid  160  with respect to the base plate  140  is associated with the position of the followers  190  on the cam  180 . This can be seen in FIGS. 4 and 5, where the position of the follower  190  at the apex  186  of the cam  180  results in a zero angular displacement, while the position of the follower  190  in the recess  183  of the cam  180  results in a maximum angular displacement or wide open. 
     To open the vent  100 , the handle  120  is moved forward or backward from its initial position (see FIG.  5 ). Since the handle  120  is rigidly connected to the lid  160  through the supports  124 , 126 , and the lid  160  is in contact at front and back edges A, B against the base plate  140 , movement of the handle  120  will cause the handle/support/lid structure to pivot about the contact with the base plate  140  at A or B. That is, a forward movement of the handle  120  (as shown in FIG. 5) will cause the handle/supports/lid structure to pivot about a contact edge A along the back of the lid  160  with the base plate  140 . Similarly, movement of the handle  120  backward will cause the handle/support/lid structure to pivot about a contact edge B along the front portion of the lid  160  with the base plate  140 . The rotation of the lid  160  and supports  124 , 126  about the base plate  140  is accommodated by the slots  130  in the base plate  140  that receive the supports  124 , 126  and the curvature of the supports at their respective lower portions. The shape of the supports&#39; lower portion is designed to avoid interference with the slot  130  as the supports  124 , 126  rotate into and out of the slots  130  in the forward and rearward directions. 
     The rotation of the handle/supports/lid is constrained by the height of the supports  124 , 126 , and further constrained by the force of the tensioning rod  112  at the followers  190  against the cam  180 . These constraints define the path that the tensioning rod (and hence the connected handle/supports/lid structure) can travel. By providing side surfaces  181  on the cams  180  defining a curved path for the follower  190 , the follower  190  remains in contact with the cam  180  as the handle  120  rotates the lid  160  open in either direction. When the follower  190  reaches the lateral cusp  187 , the rotation of the handle/supports/lid has almost progressed to its maximum open position. As the follower  190  continues along the cam  180  past the cusp  187  to the recess  183 , the rotation of the lid  160  with the base plate  140  terminates. If the height of the cam  180  is reduced by increasing the height of the spacer  182 , the distance traveled by the follower  190  and the corresponding angular distance traveled by the handle/supports/lid structure is reduced, thereby controlling the degree of opening of the vent  100 . Accordingly, the function of the spacer  182  to shorten the height the cam  180  and therefore shorten the path of the follower  190  reduces the maximum angular displacement a between the lid  160  and the base plate  140 . 
     In a preferred embodiment, the distance between the bottom of the spacer to the indenture on the apex of the cam will be 0.974 inches, and the width of the cam at the lateral cusps  187  is 0.616 inches, at the recesses is 0.539 inches, and at the second pair of lateral cusps  193  is 0.627 inches. The radius of the recess is 0.210 inches and the radius of the curved convex side surfaces is 0.948 inches. The spacer is 2.500 inches in length and 0.138 inches in height, such that the height of the cam above the spacer is 0.836 inches. In a second preferred embodiment the dimensions referenced above fall within a range of 0.100 in either direction, and in a third preferred embodiment the dimensions referenced above fall within a range of 0.200 in either direction. 
     Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described above.