Patent Publication Number: US-11655974-B2

Title: Composite fin heat sink

Description:
FIELD OF THE INVENTION 
     The present invention relates to a heat sink for a light device, and more particularly, to a composite fin heat sink for use with a light device. 
     BACKGROUND OF THE INVENTION 
     Light systems may be used in many different types of environments, including hazardous environments, to provide proper illumination to workers. The light systems are required to comply with a number of standards and regulations to ensure safety when operating equipment. 
     Because of the conditions of the environment, i.e., excessive heat, dirt, water, chemicals, etc. it is critical that the light system be maintained below a critical temperature. Conventional light systems use fin heat exchangers to dissipate heat from the light system. 
     There is a need for a heat sink with increased efficiency and less material cost. 
     SUMMARY OF THE INVENTION 
     A light device including a housing having at least one wall that defines an internal cavity. A heat sink is attached to the housing. The heat sink includes a body, a plurality of mat fins disposed about a periphery of a body, and a plurality of pin fins disposed in staggered rows on a central portion of a face of the body. The plurality of mat fins direct air in a predetermined direction to the central portion and the plurality of pin fins define a plurality of tortuous air paths along the central portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a front, perspective view of a conventional light assembly; 
         FIG.  1 B  is a perspective view of a heat sink of the conventional light assembly of  FIG.  1   ; 
         FIG.  2    is a perspective view of a heat sink according to the present invention; 
         FIG.  3    is a rear perspective view of the heat sink of  FIG.  2   ; 
         FIG.  4    is a front perspective view of the heat sink of  FIG.  2   ; and 
         FIG.  5    is a top view of the heat sink of  FIG.  2   . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings,  FIG.  1    shows a front perspective view of a conventional light assembly  10  for use in a hazardous environment. Example hazardous environments include, but are not limited to an airplane hangar, a drilling rig (as for oil, gas, or water), a production rig (as for oil or gas), a refinery, a chemical plant, a power plant, a mining operation, a wastewater treatment facility, and a steel mill. A user may be any person that interacts with example light systems in hazardous environments. Examples of a user may include, but are not limited to, an engineer, an electrician, an instrumentation and controls technician, a mechanic, an operator, a consultant, a contractor, and a manufacturer&#39;s representative. Although the light assembly  10  is described in relation to use of the light assembly  10  in a hazardous environment, the light assembly  10  is not limited to use in such environments. 
     The light assembly  10  includes one or more light sources  12  and a conventional heat sink  20  ( FIG.  1 B ) attached to a rear of the light source  12 . The light source  12  may be configured to provide light at a predetermined intensity. In this respect, the light source  12  may provide light at a single intensity or a variable intensity, as needed. 
     The light source  12  includes a housing  14 . The housing  14  can be made of one or more of a number of suitable materials to allow the light assembly  10  to meet certain standards and/or regulations while also maintaining durability in light of the one or more conditions under which the light assembly  10  can be exposed. Examples of such materials can include, but are not limited to, aluminum, stainless steel, fiberglass, glass, plastic, ceramic, and rubber. 
     It is contemplated that the light assembly  10  may be subject to meeting certain standards and/or requirements. For example, the National Electric Code (NEC), the National Electrical Manufacturers Association (NEMA), Underwriters Laboratories (UL), the International Electrotechnical Commission (IEC), and the Institute of Electrical and Electronics Engineers (IEEE) set standards as to electrical enclosures, wiring, and electrical connections. As used herein, the term “intrinsically safe” refers to a device (e.g., an example light assembly  10  herein) that is placed in a hazardous environment. To be intrinsically safe, the device uses a limited amount of electrical energy so that sparks cannot occur from a short circuit or failures that can cause an explosive atmosphere found in hazardous environments to ignite. 
     The light assembly  10  includes a conventional fin plate heat sink  20  ( FIG.  1 B ). The fin plate heat sink  20  is configured to have a predetermined heat transfer rate. Referring to  FIG.  1 B , the fin plate heat sink  20  includes a plurality of parallel fins  22  that are positioned on an outer surface of the heat sink  20 . The parallel fins  22  define straight air pathways “A” from one side of the heat sink  20  to an opposite side of the heat sink  20 . 
     Referring to  FIG.  2   , a heat sink  50 , according to the present invention is illustrated. The heat sink  50  includes a cast body  52  that is provided for transferring heat to a surrounding environment. Referring to  FIG.  3   , the cast body  52  has a recessed cavity  54  formed in a rear surface  52   a  of the body  52 . The body  52  may be made from cast aluminum. The recessed cavity  54  may be sized to received heat producing components (not shown) of the light source  12 . In this respect, the heat producing components (not shown) are in close proximity to the body  52  to provide for efficient heat transfer from the heat producing components (not shown) to the body  52 . 
     The recessed cavity  54  may have any of a number of configurations to house the heat producing components (not shown). Although the recessed cavity  54  is illustrated as having a flat bottom, it is contemplated that the recessed cavity  54  may have other shapes and/or features to aid in the efficient transfer of heat from the heat producing components (not shown) to the cast body  52 . 
     Referring to  FIG.  4   , a plurality of mat fins  62  are disposed about a periphery of the body  52 . The mat fins  62  along each side are oriented to be parallel with other mat fins  62  along the same side. In this respect, air passing between adjacent mat fins  62  is directed toward a center of the body  52 , i.e., along flow paths “B” and “C”. In the illustrated embodiment, fourteen mat fins  62  are disposed along opposite long sides  53   a  of the body  52  and seven full mat fins  62  and four shortened mat fins  62  are disposed along opposite short sides  53   b  of the body  52 . Although the body  52  is illustrated with the fourteen and eleven fins on opposite sides  53   a ,  53   b , it is contemplated that the body  52  may include any number of mat fins  62  along the edges of the body  52 . In the embodiment illustrated, the mat fins  62  are planar-in-shape with a curved outer edge portion  63   a  that transitions into an angled or sloped portion  63   b . It is contemplated that the mat fins  62  may have other shapes, for example, but not limited to, curved, sloped, etc. or any combination of the foregoing. It is also contemplated that the outer edge of the mat fins  62  may have other shapes, for example, but not limited to, straight, sloped, saw-toothed, wavey, etc. or any combination of the foregoing. In the embodiment illustrated, each of the mat fins  62  has an identical height, i.e., as measured from a base of the mat fin  62  to a distal edge of the mat fin  62 . It is contemplated that the mat fins  62  may have different heights. 
     Referring to  FIG.  5   , a plurality of pin fins  64  are positioned in a central portion  52   b  of the body  52 . The pin fins  64  are illustrated arranged in a staggered matrix arrangement wherein the pin fins  64  in one row or column are shifted or offset relative pin fins  64  in adjacent rows or columns. This arrangement of pin fins  64  creates a meandering flow path for air flowing from one side of the body  52  to the opposite side of the body  52 , see flow paths “D” and “E” in  FIG.  5   . The meandering flow paths “D” and “E” are configured to improve the heat transfer characteristics of the body  52 . In the embodiment illustrated, the pin fins  64  are cylindrical-in-shape. It is contemplated that the pin fins  64  may have other shapes, for example, but not limited to, triangular, elliptical, rectangular, prismatic, etc. In the embodiment illustrated, each of the pin fins  64  has an identical height, i.e., as measured from a base of the pin fin  64  to a distal tip of the pin fin  64 . It is contemplated that the pin fins  64  may have different heights. 
     The present invention will now be described relative to the operation of the same. During use, heat from the heat producing components (not shown) of the light source  12  generate heat that is transferred to the heat sink  50 . The heat generated is then conducted to the mat fins  62  and the pin fins  64 . The surrounding environmental air is caused to flow, via natural convection over the front face of the body  52 . In particular, the mat fins  62  direct the air flow toward the central portion  52   b  of the body  52 , i.e., along flow paths “B” and “C” ( FIGS.  4  and  5   ). Thereafter, the air flows along the central portion  52   b  of the body  52  along flow paths “D” and “E”. 
     The positioning and configuration of the mat fins  62  and the pin fins  64  are positioned to improve the transfer of heat from the heat sink  50 . The mat fins  62  have to direct the air in the proper direction whereas the pin fins  64  provide increased surface area to improve heat transfer performance. It is contemplated that the velocity of air flowing over the heat sink  50  may be double that experienced by conventional plate fins while also allow a weight reduction of about 30%. For example, testing conducted with the heat sink  50  of the present invention showed an increase in the average air velocity over the conventional heat sink  20  from 0.08 m/s to 0.17 m/s and a decrease in weight from 13.64 lbs. (for the conventional heat sink  20 ) to 9.32 lbs. (for the heat sink  50  of the present application). In this respect, the present invention may provide an increase in heat transfer efficiency with less material, as compared to conventional heat sinks. 
     It is contemplated that the aforementioned light system may be design for used in a variety of environments wherein efficient heat transfer is desired. 
     Although the invention has been described with respect to select embodiments, it shall be understood that the scope of the invention is not to be thereby limited, and that it instead shall embrace all modifications and alterations thereof coming within the spirit and scope of the appended claims.