Patent Publication Number: US-2007108305-A1

Title: Heater unit

Description:
TECHNICAL FIELD  
      The present disclosure relates to a heater unit for heating equipment.  
     RELATED ART  
      In association with the advent of multi-function control equipment, while control equipment has found various applications other than conventional ones, places where such control unit is placed are now diversified as control targets are dispersed over a wide area. In association with this trend, the number of cases is increasing where the control unit is places in sites where conditions are severe. As an example of such cases, there can be raised a pipeline control in a dry region where the temperature changes drastically within a day or a high-latitude region where it is extremely cold.  
      There are many cases where it is difficult for all electronic components ranging from their housings to constituent electronic components to satisfy required temperature specifications. In such cases, a method has been adopted in which a heater for heating the whole of the interior of an enclosure is placed together with control equipment within the enclosure so as to satisfy a temperature specification for the control equipment.  
       FIG. 6  is a perspective view which shows a heating construction for related-art communication equipment disclosed in Patent Document 1 (Japanese Patent unexamined Publication No. 2002-237693). In this communication equipment  10 , a plurality of panels of plug-in type are respectively accommodated in shelves of a shelf-type housing, and a fan unit  11  is installed at the center of the housing to equalize the temperature therein. Small heaters  13  are mounted on a back side of a front edge of each guide rail plate  12  in a dispersed fashion.  
      A temperature sensor  14  is mounted on a rear edge of an upper guide rail plate  12 , and a heater control unit  16  is mounted on a side plate  15  which switches on and off each heater so as to hold the temperature within a predetermined range based on a temperature detected by the temperature sensor  14 . Each panel is heated mainly by virtue of thermal conduction from the heater  13  via the metallic guide rail plates  12  and side plates  15 , and the fan unit  11  equalizes the temperature inside the housing.  
      The following problems are caused by the related-art heater unit.  
      (1) Since the heaters are disposed in the dispersed fashion together with the heating targets within the housing, the construction of the housing becomes complex, and this interrupts the standardization of equipment and constitutes a main cause for cost increase.  
      The number of heaters dispersed within the housing needs to be increased in order to equalize the temperature therein. Furthermore, the fan unit needs to be provided within the housing to equalize the temperature therein, which constitutes another main cause for cost increase.  
     SUMMARY  
      Embodiments of the present invention provide a heater unit which is constructed separately from equipment to be heated and which uses a temperature distribution equalizing means having an extremely simplified construction.  
      One or more embodiments of the invention will be configured as follows.  
      (1) A heater unit for heating equipment comprising:  
      a heater housing disposed on a bottom portion of the equipment in such a manner as to firmly stick thereto and having a heat source;  
      a buffer space portion formed between the bottom portion of the equipment and an upper portion of the heater housing for equalizing heat generated in the heater housing; and  
      a plurality of heating modules disposed in a dispersed fashion within the heater housing.  
      (2) A heater unit as set forth under (1), wherein the heating module includes a printed substrate on which a heating component is installed.  
      (3) A heater unit as set forth under (2), wherein the printed substrate is connected to a base substrate disposed on an inner circumferential wall of the heater housing via a connector.  
      (4) A heater unit as set forth under (3), wherein a heat insulating member is disposed on the inner circumferential wall of the heater housing which faces the base substrate.  
      (5) A heater unit as set forth under any of (2) to (4), wherein the printed substrates are disposed in a dispersed fashion in order to adjust a heat distribution within the heater housing.  
      (6) A heater unit as set forth under any of (1) to (5), wherein vent holes are formed in the upper portion and the bottom portion of the heater housing.  
      Various implementations may include one or more the following advantages. For example, the following advantages are provided.  
      (1) By disposing the heater housing immediately under the equipment separately from the equipment in such a manner as to firmly stick thereto, the construction is made simple and the standardization of equipment is not interrupted, compared to the related-art construction in which the heaters are disposed in the dispersed fashion together with the equipment to be heated thereby within the equipment housing.  
      (2) By forming the buffer space portion between the equipment to be heated and the heater housing, the construction of the housing is made simple, compared to the related-art construction in which the special fan unit is provided to equalize the temperature distribution, and this can contribute to reduction in cost.  
      (3) By making the heat sources which are disposed in the dispersed fashion within the heater housing into the modules and making, in turn, the heating modules into the form of printed substrates which are connected to the base substrate via the connecter means, not only the amount of heat for heating can be adjusted by exchanging printed substrates having different heat amounts but also the difference in supply voltage in an environment where the heater unit is used can be dealt with, thereby making it possible to develop many variations.  
      (4) Since the connecting position where the printed substrate is connected to the base substrate with the connector can be disposed in the dispersed fashion in an arbitrary pattern, the equalization in temperature distribution within the heater housing can easily be realized, and a synergetic effect with the equalization attained by the buffer space portion can be expected.  
      (5) By disposing the base substrate, the printed substrates and, furthermore, the heat insulating member in the form of a substrate in such a manner as to surround the inner circumferential wall of the heater housing, the amount of heat that escapes from side surfaces of the heater housing can be reduced, the energy can be saved, and the waiting time from the initiation of heating until the equipment can be activated can be reduced.  
      Other features and advantages may be apparent from the following detailed description, the accompanying drawings and the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a front view showing an embodiment of equipment on which a heater unit of the invention is mounted.  
       FIG. 2  is a perspective view showing an external appearance of a heater housing.  
       FIG. 3  is a perspective view showing in a perspective fashion a mounting construction of heating modules which are disposed in a dispersed fashion within the heater housing.  
       FIG. 4  is a plan view showing an example of the configuration of the heating module which is made up of a printed substrate.  
       FIG. 5  is a perspective view of a heating module which shows another embodiment of the invention.  
       FIG. 6  is a perspective view showing a heating construction of related-art communication unit. 
    
    
     DETAILED DESCRIPTION  
      Hereinafter, the invention will be described in detail by reference to the accompanying drawings.  FIG. 1  is a front view showing an embodiment of equipment on which a heater unit of the invention is mounted.  
      In  FIG. 1 , reference numeral  1  denotes rack-mounted equipment to be heated. Reference numeral  2  denotes a similarly rack mounted heater housing, which is disposed on a bottom portion of the equipment  1  in such a manner as to firmly stick thereto. Reference numeral  3  denotes a buffer space portion, which is formed between the bottom portion of the equipment  1  and an upper portion of the heater housing  2  to equalize heat generated in the heater housing  2 . Reference numeral  4  denotes heating modules, which are disposed in a dispersed fashion within the heater housing  2  with a predetermined density.  
       FIG. 2  is a perspective view showing an external appearance of the heater housing  2 . Vent holes  22  are formed continuously in an upper side panel  21 . Although not shown, similar vent holes are formed in a lower side panel. The buffer space portion  3  is realized by a space which is surrounded by upper side walls of the housing above the upper side panel  21 , and there exist no special constituent element inside the space.  
       FIG. 3  is a perspective view showing a mounting construction of the heating modules  4  which are disposed in the dispersed fashion within the heater housing  2  in a perspective fashion. The plurality of heating modules  4  are each made up of a printed substrate and are connected and held to a base substrate  5  which disposed on an inner circumferential wall portion of the heater housing  2  with a connector in a direction in which the heating modules  4  intersect the base substrate  5  at right angles. In this embodiment, the heating modules  4  are disposed and dispersed equally inside the heater housing  2 .  
       FIG. 4  is a plan view showing an example of the configuration of the heating module  4  which is made up of the printed substrate. Reference numeral  41  denotes a contact portion which is inserted into a connector provided on the base substrate  5 . Reference numeral  42  denotes a plurality of heat generating elements which are disposed on the substrate in a dispersed fashion, and a chip-shaped ceramic heater, a normal resistor element or the like can be used for the heat generating element. By disposing the heat generating elements in the dispersed fashion, heat generated on the heating module  4  can be equalized over a surface of the printed substrate.  
       FIG. 5  is a perspective view of heating modules  4  which shows another embodiment of the invention. In this embodiment, locations where the heating modules  4  are connected to a base substrate  5  are not at equal intervals but are made coarse at center and dense at both ends of a heater housing  2 , whereby the amount of heat to be generated is made large at both end portions of the heater housing  2  where heat tends to escape easily so as to equalize a heat distribution within the heater housing  2 .  
      In addition to the purpose for equalizing the temperature distribution, in the event that a specific area of equipment, above all, a specific component or location of the equipment which does not operate at low temperatures is desired to be heated, or in the event that a specific portion of the equipment needs to be heated further while the whole of the equipment is being heated, a temperature distribution of specific pattern can be realized in which the dispersion of heat sources is made unequal intentionally.  
      Thus, on one hand, a heating distribution according to a necessary degree can be realized by disposing the heat sources at unequal intervals, and on the other hand, the energy utilizing efficiency can be increased by reducing the temperature of a location where no intensive heating is required.  
      In the embodiment as shown in  FIG. 5 , by disposing the heating modules  4  at unequal intervals within the heater housing  2 , the heat distribution is adjusted. However, the adjustment of the heat distribution is not limited to this embodiment, and may be made by changing the number of the heat generating elements within the respective heating modules  4  in accordance with the location of the heating modules  4 . For example, in a case where the heating modules  4  are disposed at equal intervals within the heater housing  2 , the number of the heat generating elements within the heating modules  4  located in the center of the heater housing  2  may be made smaller than that of the heat generating elements within the heating modules  4  located at both ends of the heater housing  2 .  
      In this invention, by disposing the base substrate and the printed substrates which make up the heating modules  4  in such a manner as to surround the inner circumferential walls of the heater housing  2 , the amount of heat which escapes from the side surfaces of the heating housing can be reduced, so that the energy can be saved and the waiting time from the initiation of heating until the equipment can be activated can be reduced.  
      Furthermore, by disposing the heat insulating member which is similar to the printed substrate on the inner circumferential surface of the heater housing  2  which faces the base substrate  5 , the four inner circumferential walls are surrounded by the heat insulating members including the base substrate  5  and the heating modules  4 , so that the energy utilization efficiency can be increased further.