Patent Publication Number: US-6663264-B2

Title: Lamp assembly with ventilation system

Description:
FIELD OF INVENTION 
     The present invention relates to a ventilation system for a lamp assembly, such as an automotive headlamp, fog lamp, signal light, or taillight. More specifically, it relates to a lamp assembly having an optical and/or non-optical shield coupled to a ventilation air passage, such that a cavity of the lamp assembly may be ventilated to an ambient environment. 
     BACKGROUND OF THE INVENTION 
     A concern that frequently arises during the design of automotive lighting devices is the need to provide proper ventilation for an interior of a housing or body of the lighting device. While adequate ventilation is important for both lighting device functionality and appearance, the automotive lighting device design should also take into account the prevention of fogging of the lighting device lens. Device design should also take into account the unwanted penetration of water, dirt, dust and other contaminants from a surrounding ambient into the lighting device cavity. These design concerns can be especially important where the lighting device resides on the exterior of an automobile that is subject to high speeds, inclement weather, and high water pressure situations (e.g., a car wash). 
     Such design concerns also arise when designing an optical and/or non-optical lighting device to ventilate internally generated heat. For example, during use, a bulb of a typical lamp reaches relatively high temperatures. Heat transferred from the bulb can melt, deform, or otherwise damage the lamp housing surrounding the bulb, especially when the lamp housing is made from an inexpensive plastic material. While any side of the lamp housing may have one or more areas susceptible to heat damage, the top side of the lamp housing above the bulb generally suffers the greatest damage due to heat transfer by free, or natural, convection from the bulb. 
     A known method of ventilating lighting devices is to provide the lighting device with a system of chicanes, labyrinths or air ducts that create a tortuous path. Such a known device is disclosed in U.S. Pat. No. 5,758,957 to Perrotin which is herein incorporated by reference and to which the reader is directed for further details. In this known device, a labyrinth path is provided. This path is an air passage provided with a number of angles. This labyrinth passage deters ingress of moisture and dust but, at the same time, allows air transfer between the lamp and the environment to equalize pressure and, if applicable, transfer heat. In other words, this allows the lamp to “breathe” while also reducing the potential for fogging and condensation. 
     Such known lighting devices have a number of manufacturing and design disadvantages. For example, where the lighting device is an injection molded device, creating a torturous path in an injection molded part may be difficult. Creating a passage of two complete or more 90° turns with a single tool injection molded component creates manufacturing complexities because it requires more than one die draw direction. 
     Other known ventilation designs utilize additional rubber parts to provide a torturous path, such as a macaroni tube, that attaches snuggly to a vent boss on the housing. The addition of a number of rubber parts also add cost in the form of material, assembly time, and warranty/quality because these vents often fall off or are forgotten. Extra lamp device pieces also increase the overall weight of the device. 
     Accordingly, it would be desirable to have a lighting device ventilation system that overcomes the problems associated with known systems. 
     There is a general need for reducing the cost of a lighting device system. There is also a need for a vent system that does not require a macaroni or other angled tube. There is a further need for combining lamp components while also reducing the complexity of molding tools. 
     SUMMARY OF THE INVENTION 
     The present invention provides a lamp assembly including a lamp housing defining a cavity. The lamp housing has at least one side with a vent passage. A heat shield is coupled to at least one side and at least partially aligned with the vent passage to provide ventilation to the lamp housing. 
     In another embodiment, a vehicle lighting device includes a lamp housing defining a cavity. The lamp housing has at least one side provided with a ventilation opening. A bulb shield insert that has an attachment mechanism is at least partially aligned with the ventilation opening. The attachment mechanism at least partially allows for ventilation of the cavity. A bulb shield stem extends from the bulb shield insert. The bulb shield stem has a bulb shield cover adapted to at least partially cover a bulb. 
     A method for ventilating a lamp assembly is also disclosed. The method includes defining an internal cavity of a lamp housing. A vent passage is provided in a side of the lamp housing. A heat shield is coupled to the at least one side; and at least partially aligning the heat shield with the vent passage to provide ventilation to the lamp housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a back perspective view of a preferred embodiment of a lamp assembly illustrating one aspect of the present invention; 
     FIG. 2 is a cross-sectional view of the lamp assembly of FIG. 1 taken along line A—A; 
     FIG. 3 is a perspective view of one embodiment of a bulb shield attachment stem; 
     FIG. 4 is a side view of a first embodiment of the bulb shield attachment stem illustrated in FIG. 3; 
     FIG. 5 is a side view of a second embodiment of the bulb shield attachment stem illustrated in FIG. 3; and 
     FIG. 6 is a side view of yet another embodiment of the bulb shield attachment stem illustrated in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Turning now to the drawings, FIGS. 1-2 show a preferred embodiment of a lamp assembly  5  of the present invention. The lamp assembly  5  comprises a lamp bulb  10 , a lamp housing  20 , a lens  72 , and a bulb shield  90 . The bulb shield  90  has a bulb shield insert  80  that acts as an engagement mechanism and is preferably spring compression engaged into a vent passage  29 . 
     The lamp bulb  10  has a light and heat generating filament portion  12 , and a socket  14  opposite the filament portion. It should be understood, however, that the socket  14  may be an integral component of the lamp bulb  10 , or alternatively, may be a separate component connected to the lamb bulb  10 . Although an incandescent bulb is shown in FIG. 1, it should also be understood that any desirable type of lamp bulb may be used with the lamp assembly of the present invention, depending upon regulatory, manufacturing, and/or consumer preferences. 
     As shown in FIG. 2, the lamp housing  20  defines a cavity  21 . Preferably, but not necessarily, the lamp housing  20  is made from a plastic, such as polycarbonate or ABS. 
     The lamp housing  20  also has a top side  22  with an interior surface  22   a  facing the cavity  21 , and an exterior surface  22   b  opposite the interior surface  22   a . The top side  22  also has a front end  24  with a lens slot  26 , and a second end  28 . The second end  28  and a back portion  30  of the lamp housing  20  partially define a vent passage  29 . 
     The vent passage  29  is preferably located in the back portion  30  and adjacent the socket  14 , because an energized light bulb heats and forces the air upward in the center of the lamp. The hotter the air, the higher the amount water vapor the air can potentially hold. Egressing as much of this hot, potentially moist, air as possible is advantageous. It should be understood, however, that the vent passage may be located elsewhere within the lamp housing (i.e., another side or beneath the socket  14 ). Other locations will depend on the configuration of the lamp assembly. The vent passage  29  provides an outlet for releasing excess fluids, heat, and/or pressure within the cavity  21  of the lamp housing  20 . The vent passage  29  also reduces the amount of fluids, dirt, etc. entering the cavity. As will be detailed below, the vent passage also serves to provide a coupling means for a bulb shield. 
     The lamp housing  20  also has a bottom side  32  with an interior surface  32   a  facing the cavity  21 , and an exterior surface  32   b  opposite the interior surface  22   a.  The bottom side  32  also has a front end  34  with a lens slot  36 , and a second end  38 . The second end  38  partially defines a bulb socket aperture with the back portion  30  of the lamp housing  20 . 
     The lamp housing  20  also has a first side  42  and a second side  52  spaced from the first side. The first and second sides  42 ,  52  connect the top side  22  to the bottom side  32 , and may be curved, as shown in FIG.  1 . Like the top side  22  and the bottom side  32 , the first side  42  and the second side  52  each have a first end  44 ,  54  with a lens slot  46 ,  56 , and a second end  48 ,  58 , respectively. 
     The lamp housing  20  further includes a back side  62 . The back side  62  has a first end  64  and a second end  68  connected to the second ends  28 ,  38 ,  48 ,  58  of the top, bottom, first and second sides  22 ,  32 ,  42 ,  52 . The bulb socket  14  is adapted to receive and hold the socket  4  of the lamp bulb  10 . Preferably, the back side  62  is at least partially curved and has a reflective inner surface  70  for reflecting and imaging emitted light from the lamp bulb  10  forward away from the back side  62 . 
     In addition, the top, bottom, first, second and back sides  22 ,  32 ,  42 ,  52 ,  62  are preferably formed integral with one another. For instance, injection molding may be used to form the top, bottom, first, second, and back sides  22 ,  32 ,  42 ,  52 ,  62 . 
     As shown in FIG. 2, the bulb shield  90  comprises a bulb shield cover  92 , a bulb shield stem  94 , and a bulb shield insert  80 . The bulb shield insert  80  is preferably removably attached to the vent passage  29 . In the preferred embodiment shown in FIG. 2, the vent passage  29  is defined at least partially by second end  28  of the top side  22  and at least partially by a top portion  102  of back portion  30  and the bulb shield insert  80  may be spring compression engaged in the vent passage  29 . It will be understood that other types of engaging devices may also be used to removably attach the insert  80  into the vent passage. Other attachment designs include those that produce pressure on the vent walls for rigidity, snap fit designs, or those that may require a separate fastener. Alternatively, a fixedly attached engaging device may be used. 
     In the embodiment illustrated in FIGS. 1 and 2, the bulb shield insert  80  includes an attachment mechanism  81 . In one preferred embodiment, the attachment mechanism  81  is a spring. The configuration of the attachment mechanism  81  allows the bulb shield to be removably inserted into the vent passage  29  while simultaneously allowing air flow through the vent passage  29 . Because the insert and in particular the attachment mechanism  81  does not completely obstruct the air passage, the configuration of the attachment mechanism  81  enables air flow between the cavity  21  and the exterior of the lamp assembly  5  thereby providing ventilation to the lamp assembly. 
     Preferably, the shape and size of the attachment mechanism  81  is configured to generally match the shape and size of a vent passage opening  82 . The attachment mechanism  81  is preferably made from steel. Alternatively, attachment mechanisms may be made from other materials, such as aluminum or copper, that can generally withstand relatively high temperatures. Since the vent passage opening  82  may be located within one of the other lamp assembly  5  sides (i.e., bottom side  32 , first side  42 , or second side  52 ), and the attachment mechanism  81  is mounted in the vent passage opening  82 , it should be understood that the attachment mechanism  81  may also be mounted on one of the other sides, and hence the bulb shield  90  may be engaged in other sides of the lamp assembly, such as for example in the first side  42  (i.e., a side surface). In addition, it should be further understood that with the lens  72  and the attachment mechanism  81  being connected and mounted to the lamp housing  20 , and without any further requirement for vent holes, the lens  72 , the attachment mechanism  81 , and the lamp housing  20  together form a sealed lamp assembly  5 . 
     FIG. 2 also shows that the vent passage  29  has an inner vent passage opening  112  along with the vent passage opening  82 . A labyrinth path  110  is defined through both of the openings  82  and  112 . 
     FIG. 3 is a perspective view of a first embodiment of the bulb shield attachment mechanism  100  of the bulb shield  90  of the present invention. As seen from FIG. 3, the mechanism  100  includes a top surface  107  and a bottom surface  109 . A spring  105  is provided along the top surface  107 . In this embodiment, the spring  105  resides along a center portion of the spring top surface  107 . The spring  105  resides along the top surface of the mechanism however it will be generally understood that other configurations are possible. For example, the bulb shield attachment mechanism  100  could include multiple springs, different spring locations, etc. 
     The bulb shield attachment mechanism  100  also has a width and preferably this width is non-uniform. Such a non-uniform width may be tapered into a configuration such that it has a dimension that is slightly smaller than an inner width of the vent passage (See FIG.  2 ). With such a tapered configuration, when the attachment mechanism is coupled to the vent passage, the non uniform width compression engages the vent passage inner walls and becomes removably or fixedly attached. 
     A ridge  111  is also provided along an edge of the insert. This ridge reinforces the structure of the attached mechanism. 
     As the attachment mechanism  100  is inserted into a lamp assembly vent passage, and depending on the spring configuration, the spring  105  may become compressed by either a vent passage top wall, a vent passage bottom wall, or alternatively a vent passage side wall. The compressed spring then attaches the attachment stem within the vent passage. Importantly, the spring configuration allows air flow between the lamp assembly cavity and ambient. 
     Returning to FIGS. 1-2, the lamp assembly  5  comprises a bulb shield  90  with a cover  92  and a bulb shield stem  94 . The cover  92  is adapted and designed to at least partially cover the filament portion  12  of the lamp bulb  10 . The stem  94  is connected to both the cover  92  and the bulb shield insert  80  which is connected to the attachment mechanism  81 , thereby providing a conduit for heat to be transferred from the bulb shield  90  to the attachment mechanism  81 . Preferably, but not necessarily, both the cover  92  and the stem  94  are made from steel. Alternatively, the cover  92  and/or the stem  94  of the bulb shield  90  may be made from other materials, such as aluminum or copper. 
     FIGS. 4-6 show alternative embodiments of the attachment mechanism and vent passages of the present invention. The vent passages illustrated in FIGS. 4-6 operate in the same manner as, the vent passage  90  shown in FIGS. 1-2, with certain slight structural differences. 
     For example, as can be seen from FIG. 4, an attachment mechanism  115  is operatively coupled to a vent passage  113 . The attachment mechanism  115  includes a spring  117  which compressionly engages a top portion  114  of the passage  113 . 
     FIG. 5 includes an attachment mechanism  121  coupled to a vent passage  119 . The attachment mechanism  121  includes a spring  123  which compression engages a bottom portion  120  of the passage  119 . And in FIG. 6, an attachment mechanism  129  is shown coupled to a vent passage  125 . The attachment mechanism  129  includes a spring  131  which compression engages a bottom portion  128  of the passage  125 . 
     One difference between the vent passage  125  of FIG.  6  and the vent passage of FIG. 4 is that vent passage  125  is not a stepped passage. Rather, passage  125  is a linear passage having a generally smooth top portion and a smooth bottom portion  128 . In this embodiment, a spring lever engages a bottom reflector wall rather than a top reflector wall. Alternatively, the attachment spring could engage a top portion of the passage. 
     While the lamp assemblies of the present invention may be applied with particular advantage to head lamps, fog lamps, signal lights, and/or taillights of automotive vehicles, the lamp assemblies of the present invention may also be used with other lamps and lights for automotive vehicles, or with lamps and lights unrelated to automotive vehicles. It should also be readily apparent from the foregoing description and accompanying drawings that the lamp assemblies of the present invention are improvements over the prior art. In particular, the lamp assemblies of the present invention allow the vent to be concealed from observation through the lens of the lamp and reduce cost by combining the shield attachment slot with the vent hole. 
     Those skilled in the art to which the invention pertains may make modifications and other embodiments employing the principles of this invention without departing from its spirit or essential characteristics, particularly considering the foregoing teachings. Accordingly, the described embodiments are to be considered in all respects only as illustrative and not restrictive, and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. Consequently, while the invention has been described with reference to particular embodiments, modifications of structure, sequence, materials, and the like would be apparent to those skilled in the art, yet would still fall within the scope of the invention.