Patent Publication Number: US-8967842-B2

Title: Lamp condensation reduction system

Description:
BACKGROUND 
     Enclosed vehicle lamp housings can include light sources such as vehicle headlamps, running lamps, fog lights, brake lamps, parking lights, and turn indicator lights for use in safe operation of a vehicle. The lamp housings are enclosed and/or sealed both for overall appearance of the vehicle and to prevent debris, water, or other contaminants from negatively impacting the effectiveness of the light source and reflective surfaces within the lamp housing. The air contained within the vehicle lamp housing may initially include, or can develop, some measure of humidity or moisture. The air within the vehicle lamp housing is also subject to rapidly changing temperatures depending on environmental conditions surrounding the vehicle and heat present within the vehicle lamp housing emitted by one or more of the light sources. As moist air cools from a heated state, condensation can form in areas of the enclosed vehicle lamp housing that are not adequately heated or vented. 
     SUMMARY 
     Lamp assemblies for reducing headlamp condensation are disclosed. 
     In one implementation, an example lamp assembly for reducing condensation is disclosed. The lamp assembly includes a rear housing; a front housing configured to mate to the rear housing to form a lamp cavity; a light source extending from the rear housing into the lamp cavity; a reflector extending from the rear housing toward the front housing adjacent to the light source; and a duct including a rear duct wall and spaced side duct walls extending between the rear housing and the reflector from the light source to a remote section of the lamp cavity spaced from the light source. The duct and a wall of the reflector form a duct cavity configured to draw air from the remote section of the lamp cavity toward the light source. 
     In another implementation, another example lamp assembly for reducing condensation is disclosed. The lamp assembly includes a rear housing; a front housing configured to mate to the rear housing to form a lamp cavity; a light source extending from the rear housing into the lamp cavity; a reflector extending from the rear housing toward the front housing adjacent to the light source; and a pair of spaced side duct walls extending substantially perpendicularly from the rear housing toward the reflector and extending from the light source to a remote section of the lamp cavity spaced from the light source. A front wall of the rear housing and a rear wall of the reflector and the spaced side duct walls form a duct cavity configured to draw air from the remote section of the lamp cavity toward the light source. 
     In another implementation, another example lamp assembly for reducing condensation is disclosed. The lamp assembly includes a lamp housing including a front housing and a rear housing forming a lamp cavity; a light source extending from the rear housing into the lamp cavity; a reflector extending around the light source; and a duct extending between the rear housing and the reflector from the light source to a remote section of the lamp cavity spaced from the light source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  is a front view of a vehicle headlamp assembly in accordance with one or more embodiments; 
         FIG. 2  is an exploded view of the vehicle headlamp assembly of  FIG. 1 ; 
         FIG. 3  is a sectional view through a section of the vehicle headlamp assembly designated in  FIG. 1 ; 
         FIG. 4  is a front view of the rear housing and an example duct within the vehicle headlamp assembly of  FIG. 1 ; and 
         FIG. 5  is a front view of the rear housing of  FIG. 1  and an alternative example duct design. 
     
    
    
     DETAILED DESCRIPTION 
     Lamp assemblies designed to reduce condensation are described below. The lamp assemblies can include a transparent or semi-transparent front housing mated to a rear housing to form a sealed lamp cavity and one or more light sources extending from the rear housing into the lamp cavity. Each of the light sources can include a reflector extending from the rear housing around the light source configured to reflect light from the light source through the front housing. The lamp assemblies can also include a duct extending between the rear housing and the reflector from the light source to a remote section of the lamp cavity spaced from the light source. The duct can be integrated into the rear housing or separately mated to the rear housing, and when installed behind the rear wall of the reflector, can form a duct cavity to draw cool air from a remote section of the lamp cavity toward the light source. Once the air is heated, it rises and starts a circulation path within the sealed lamp cavity, reducing condensation formation in remote sections of the lamp cavity. 
       FIG. 1  is a front view of a vehicle headlamp assembly  100  in accordance with one or more embodiments. The example headlamp assembly  100  shown here includes two light sources: a park and turn lamp  102  and a high and low beam lamp  104 . Each of the lamps  102 ,  104  is surrounded by a reflector. The park and turn reflector  106  extends around the park and turn lamp  102 , and the main reflector  108  extends around the high and low beam lamp  104 . Each of the reflectors  106 ,  108  can reflect light emitted by one of the lamps  102 ,  104  and is shaped to direct and intensify the light being projected from the headlamp assembly  100 . 
     The headlamp assembly  100  of  FIG. 1  can include a rear housing  110 . The rear housing can include various means for attaching the headlamp assembly  100  to a vehicle, for example, brackets, tabs, or shelf extensions either including or designed to receive various fasteners. One example bracket  112  is shown as including a nut  114  for use in attaching the headlamp assembly  100  to a vehicle. The rear housing  110  can also include means for attaching or receiving the lamps  102 ,  104  and for attaching the reflectors  106 ,  108  which extend from the base of each lamp  102 ,  104  to partially surround the lamps  102 ,  104 . 
     The headlamp assembly  100  can also include a front housing  116  designed to mate to the rear housing  110 . The front housing  116  can be substantially transparent to allow light to pass through it. Mating the front housing  116  and the rear housing  110  can form a lamp cavity, the lamps  102 ,  104  and reflectors  106 ,  108  being disposed within the lamp cavity. The rear housing  110  and front housing  116  can also be designed to include seals or other complementary surfaces that keep air, water, and other debris from entering the lamp cavity and affecting the operation of the lamps  102 ,  104  and reflectors  106 ,  108 . Despite effective sealing between the rear housing  110  and front housing  116 , some level of moisture can be trapped or can become present in the air sealed within the lamp cavity. 
     The headlamp assembly  100  of  FIG. 1  can also include a decorative bezel  118 . The bezel  118  can be installed between the front housing  116  and the reflectors  106 ,  108  in order to optimize the path of light being emitted from the headlamp assembly  100  through the front housing  116 . The bezel  118  can also be installed to improve the appearance of the headlamp assembly  100  and/or cover other internal components within the headlamp assembly  100 . In other example headlamp assemblies, the bezel  118  can be absent. 
     The headlamp assembly  100  can also include a duct  120  extending between the rear housing  110  and the park and turn reflector  106  from the park and turn lamp  102  to a remote section of the lamp cavity spaced apart from the park and turn lamp  102  as shown in  FIG. 1 . An additional or alternate duct (not shown) can be positioned to extend between the rear housing  110  and the main reflector  108  from the high and low beam lamp  104  to a different remote section of the lamp cavity spaced apart from the high and low beam lamp  104 . In some embodiments, the remote section of the lamp cavity is below the light source, e.g. the park and turn lamp  102  or the high and low beam lamp  104 . 
     The dotted line shown in  FIG. 1  extends from the top center of the headlamp assembly  100  through the rear housing  110  and the front housing  116 , through the bezel  118 , through the park and turn reflector  106  and the park and turn lamp  102 , through the duct  120 , through the remote section of the lamp cavity spaced from the park and turn lamp  102 , and back through the bezel  118  and front housing  116 . The sectional view through the dotted line is further described in reference to  FIG. 3  below. The location and function of the duct  120  is further described in reference to exploded  FIG. 2  and the sectional view of  FIG. 3  below. 
       FIG. 2  is an exploded view of the vehicle headlamp assembly  100  of  FIG. 1 . As described in  FIG. 1 , the headlamp assembly  100  includes the transparent, or partially transparent, front housing  116 . The bezel  118  is located beneath the front housing  116 . The park and turn reflector  106  is located beneath the bezel  118  and can include a lamp opening  200  for receiving the park and turn lamp  102  which extends from the rear housing  110 . The rear housing  110  also includes various means for attaching the headlamp assembly  100  to a vehicle, for example, bracket  112  extending from the rear housing  110 . 
     The duct  120  can extend between the park and turn reflector  106  and the rear housing  110  and can include a rear duct wall  202  and spaced side duct walls  204 ,  206 . The duct  120  can also include brackets, such as bracket  208 , or other means for mounting the duct  120  to the rear housing  110  beneath the park and turn reflector  106 . In the example headlamp assembly  100  shown in  FIG. 2 , the duct  120  extends from the base of the park and turn lamp  102  substantially vertically toward a section of the rear housing  110  remote from the park and turn lamp  102 . In this example, the remote section is in a lower corner of the rear housing  110 , below the bezel  118 , where the rear housing  110  mates with the front housing  116 . 
     Remote sections of the lamp cavity include those sections of the lamp cavity that are spaced apart from a light source. The air within the remote sections remains cooler than air located in close proximity to one or more light sources, for example, the park and turn lamp  102 , based at least partially on the spacing between the remote sections and the light sources. When the headlamp assembly  100  is installed in a vehicle, the outer surface of the front housing  116  is also exposed to environmental elements such as rain, snow, wind, and cold air, affecting the temperature of both the outer surface of the front housing  116  and the inner surface of the front housing  116  adjacent to remote sections of the lamp cavity. Both the remoteness from a light source and the proximity to external weather conditions can cause a rapid cooling of air in one or more remote sections of the lamp cavity, leading to condensation forming in those remote sections of the lamp cavity if moisture is present in the air and the air remains stagnant in the remote sections of the lamp cavity. 
     The rear duct wall  202  and spaced side duct walls  204 ,  206  form three sides surrounding a duct cavity. The duct cavity is configured to draw air from the remote section of the lamp cavity toward the light source, e.g. the park and turn lamp  102 . The fourth side surrounding the duct cavity is formed by a rear wall of the park and turn reflector  106 , thus the duct cavity is an essentially enclosed channel between the remote section and the light source. To either reduce condensation or prevent condensation from occurring in the remote section of the lamp cavity, the park and turn lamp  102  can be operated to heat the air around it, that is, the air at the top of the duct  120 . Since heated air expands to a lower air pressure, cooler air having a higher pressure is drawn through the duct cavity from the remote section toward the light source. The draw of air through the duct  120  is one part of the recirculation process that can occur within the lamp cavity to reduce or prevent condensation. The rest of the recirculation process is described in respect to  FIG. 3 . 
       FIG. 3  is a sectional view through a section of the vehicle headlamp assembly  100  designated in  FIG. 1 . At both the top and bottom of the sectional view, the rear housing  110  is joined and sealed to the front housing  116  to form the lamp cavity. The park and turn lamp  102  extends from the rear housing  110  into the lamp cavity. The park and turn reflector  106  surrounds the park and turn lamp  102 , extending from the rear housing  110  toward the front housing  116 . The bezel  118  is shown as extending from the edges of the park and turn reflector  106  to the walls of the front housing  116 . Finally, the duct  120  is shown as extending from the park and turn lamp  102 , below the park and turn reflector  106 , toward a lower portion of the bezel  118  located in a section of the lamp cavity remote from the park and turn lamp  102 . 
     An opening  300  can be formed in a lower portion of the bezel  118  such that air can travel between the portion of the lamp cavity proximate to the front housing and the portion of the lamp cavity proximate to the rear housing  110 . The duct  120  and park and turn reflector  106  form a duct cavity that draws air from the opening  300  in the bezel  118  toward the park and turn lamp  102  based on the difference in temperature and pressure at the ends of the duct cavity. Path A is shown in  FIG. 3  detailing the travel of air from the opening  300  in the bezel  118  to the portion of the lamp cavity proximate to the park and turn lamp  102 . Once the air is heated by the park and turn lamp  102 , path B shows the travel of the air away from the park and turn lamp  102  along the wall of the park and turn reflector  106  toward a remote section of the lamp cavity at the top of the headlamp assembly  100  between the bezel  118  and the front housing  116 . 
     One the air reaches the remote section of the lamp cavity at the top of the headlamp assembly  100  between the bezel  118  and the front housing, the air can become cooler based on its remoteness from the park and turn lamp  102  as well as on environmental conditions external to the headlamp assembly  100  that impact the front housing  116 . Once it cools, the air starts to sink, flowing along the face of the front housing  116  as shown in path C, down toward the remote section of the lamp cavity between the bezel  118  and front housing  116  at the bottom of the headlamp assembly  100 . Before the air can be cooled to a point that condensation would form, it is drawn through the opening  300  in the bezel  118  into the duct  120  and rises toward the park and turn lamp  102  as described above along path A. The air flows from path A to path B to path C as it heats and cools, reducing or eliminating the formation of condensation in remote sections of the lamp cavity. 
       FIG. 4  is a front view of the rear housing  110  and an example duct  120  within the vehicle headlamp assembly  100  of  FIG. 1 . The example duct  120  shown includes a rear duct wall  202 , side duct walls  204 ,  206  and a pair of brackets  208  for mating the duct  120  to the rear housing  110 . The duct  120  extends substantially vertically between an opening  400  in the rear housing  110  for receiving a light source and a lower portion of the rear housing  110 . The twisting shape of the duct  120  is such that the side duct walls  204 ,  206  extend to reach a rear wall of the park and turn reflector  106  (not shown here) to form the duct cavity to draw air from the lower portion of the rear housing  110  toward the light source. 
       FIG. 5  is a front view of the rear housing  110  of  FIG. 1  and an alternative example duct  120  design. In this example, the pair of spaced side duct walls  204 ,  206  extend substantially perpendicularly from the rear housing  110  to reach a rear wall of the park and turn reflector  106  (not shown here) to form the duct cavity to draw air from the lower portion of the rear housing  110  toward the light source. As shown by the examples in  FIGS. 4 &amp; 5 , the spaced side duct walls  204 ,  206  can be formed as part of a separate duct  120  to be mated to the rear housing  110  or can be integrated directly into the rear housing  110 , depending on design constraints for the headlamp assembly  100 . 
     The foregoing description relates to what are presently considered to be the most practical embodiments. It is to be understood, however, that the disclosure is not to be limited to these embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.