Abstract:
An apparatus for cooling power components includes a first clamping portion, the first clamping portion having a first arcuate engagement surface, and a first interface. A second clamping portion, the second clamping portion having a second arcuate engagement surface, and a second interface. A flexible heat transfer pad and a power component. The power component is coupled to the flexible heat transfer pad, such that the flexible heat transfer pad substantially surrounds the power component, the first clamping portion and the second clamping portion configured to be coupled, such that the first arcuate engagement surface and the second arcuate engagement surface form an opening contoured to receive the power component, and the first interface and the second interface are adjacent to each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The subject matter disclosed within generally relates to industrial control systems, and more particularly to systems and methods that provide cooling mechanisms for power components associated with industrial control systems. 
         [0004]    Industrial control systems, by their nature, are located in a variety of environments. Some of these environments can have a variety of air-born contaminates that can be damaging to electrical components. Alternatively, certain environments may require regular cleaning with water and/or other chemicals which can also damage sensitive electrical and power components. Further, some environments may require pressure washing, requiring electrical enclosures to prevent liquids from contacting the electrical components, causing damage or dangerous situations. Thus, installation of industrial control systems in environments containing potential contaminates can require specialized installation systems to protect the electrical components. 
         [0005]    When industrial control systems are installed in environments where they are required to be isolated from potential contaminates, the electrical components are often placed in an enclosure. These enclosures, depending on the level of sealing necessary, can be designed to prevent the ingress of liquids, or, in certain situations, from the outside air in general. As these sealed enclosures are generally more expensive than standard electrical enclosures, they are often sized to accommodate multiple components such that the number of enclosures needed can be reduced. This often results in long cabling and conduit runs to and from various equipment and processes; thereby increasing both cost and complexity to a system. 
         [0006]    Additionally, the sealed nature of these enclosures required them to, generally, be larger than non-sealed enclosures in order to accommodate the heat generated by the internal electrical components. As the enclosures can be required to be sealed from the outside air, efficient cooling of the internal electrical components is difficult and often requires significant oversizing of the enclosure to ensure that the heat can be adequately dissipated. This additional size further increases material cost of the enclosures and requires more of the industrial environment real estate be allocated for these enclosures. This inefficient use of space can have a significant impact on the efficiency and utilization of the industrial environment in addition to requiring additional capital for the materials and installation. 
         [0007]    Passive heat dissipation devices such as heat sinks can be used to dissipate heat produced by the components. Additionally, heat sinks can be used in conjunction with an active cooling device such as a stirring fan, or, where feasible, used in lieu of an active cooling device. Heat sinks require additional space in the enclosure and sufficient air volume to effectively dissipate the generated heat. Further, heat sinks can be difficult to apply to certain power components due to their geometrical features. A prime example are power capacitors, such as those used as bus capacitors for variable frequency drives. These devices are often cylindrical and, in some instances, fragile. Attempts at removing heat from power capacitors with a heat sink can be difficult as heat sinks rely on a thermally efficient coupling to the device to properly dissipate heat from the component. Thermally efficient coupling is generally accomplished by placing as much of the component as possible in contact with the heat sink with a tight physical connection to ensure heat can easily transfer from the component to the heat sink. 
         [0008]    Generally, components are connected to a heat sink on a substantially flat portion of the component to allow for the greatest surface area to be in contact with the heat sink. These substantially flat surfaces are also generally the strongest portions of the components, allowing for a strong coupling between the component and the heat sink. However, capacitors, and particularly power capacitors, are generally cylindrical in shape, thereby making it difficult to couple a heat sink to the capacitor. Further, cylindrical capacitors can be easily deformed with little force. Deformation of the power capacitors can affect the properties of the capacitor adversely, even causing failures, which can result in unplanned downtime to repair. This is made more complicated by the non-uniformity of many power capacitors, making it difficult to produce a heat sink that can couple to the power capacitor to allow for efficient cooling while preventing any physical deformation or damage to the power capacitor. 
         [0009]    Thus, it would be advantageous to have devices and methods that allows for a heat sink to be safely and efficiently coupled to a power component, such as a capacitor, to efficiently cool the power component while reducing the likelihood of physical damage to the power component. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    An embodiment of an apparatus for cooling power components includes a first clamping portion, the first clamping portion having a first arcuate engagement surface, and a first interface. A second clamping portion, the second clamping portion having a second arcuate engagement surface, and a second interface. A flexible heat transfer pad and a power component. The power component is coupled to the flexible heat transfer pad, such that the flexible heat transfer pad substantially surrounds the power component, the first clamping portion and the second clamping portion configured to be coupled, such that the first arcuate engagement surface and the second arcuate engagement surface form an opening contoured to receive the power component, and the first interface and the second interface are adjacent to each other. 
         [0011]    An embodiment of a method of cooling power components includes surrounding a power component with a flexible heat transfer pad, locating the power component adjacent to a first arcuate engagement surface of a first clamping portion, coupling a second clamping portion to the first clamping portion having a first arcuate engagement surface, the first arcuate engagement surface and the second arcuate engagement surface engaging the flexible heat transfer pad, and securing the first clamping portion to the second clamping portion to clamp the power component and the flexible heat transfer pad using a fastening device. 
         [0012]    An embodiment of a power capacitor heat-dissipating clamping device includes a first clamping portion integrally formed with a heat sink, the first clamping portion having a first generally arcuate engagement surface, and a first interface. A second clamping portion, the second clamping portion having a second generally arcuate engagement surface, and a second interface. A flexible heat transfer pad, and a cylindrical power component. The power component is coupled to the flexible heat transfer pad, such that the flexible heat transfer pad substantially surrounds the power component, the first clamping portion and the second clamping portion configured to be coupled, such that the first arcuate engagement surface and the second arcuate engagement surface form an opening contoured to receive the power component, and the first interface and second interface are adjacent to each other. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]    The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
           [0014]      FIG. 1  illustrates a front-view of an example embodiment of a power component clamping assembly. 
           [0015]      FIG. 2  is a magnified view of an embodiment of the power component clamping assembly. 
           [0016]      FIG. 3  is a front-view of an embodiment of a multiple power component clamping assembly. 
           [0017]      FIG. 4  is an isometric view of an embodiment of an integrated heat sink clamping device. 
           [0018]      FIG. 5  is a cross-sectional isometric view of an embodiment of an integrated heat sink clamping device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The present invention is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It may be evident, however, that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the present invention. 
         [0020]      FIG. 1  illustrates a possible embodiment of a power component clamping device  100 . The single component clamping device  100  can have a lower portion  102  and an upper portion  104 . Lower portion  102  and upper portion  104  can be machined metal. In one embodiment, lower portion  102  and upper portion  104  can be casted metal. Additionally, other suitable methods of manufacture as known in the art can be used, such as metal injection molding (MIM), stamping, etc. Lower portion  102  and upper portion  104  can be formed of a metal or metal alloy having thermal and electrical conductivity. Non-limiting examples include steel, aluminum and copper. In a preferred embodiment, lower portion  102  and upper portion  104  can be made of the same material in order to ensure consistent thermal expansion and contraction between the upper portion  104  and the lower portion  102 . 
         [0021]    Lower portion  102  can have a substantially flat lower surface  106  that can be used to mount lower portion  102  to a corresponding surface. In one embodiment, the corresponding surface can be a heat sink. The lower portion  102  can further have a plurality of attachment points  108 ,  110  for coupling the lower portion  102  to a corresponding surface. The plurality of attachment points  108 ,  110  can be through holes which allow for a fastener device to be used to allow for fastening devices to be passed through. Additionally, attachment points  108 ,  110  can be threaded through holes which allow for threaded fasteners to couple lower portion  102  to a corresponding surface. Lower portion  102  can also feature extended mounting tabs  112 ,  114 . Attachment points  108 ,  110  can be located on mounting tabs  112 ,  114  as illustrated in  FIG. 1 . Alternatively, mounting tabs  112 ,  114  can be used as a clamping point to allow for lower portion  102  to be clamped to a corresponding surface. Lower portion  102  can further have a substantially flat upper surface  116 . Lower portion  102  can also have a plurality of coupling apertures  118 ,  120 . A plurality of lower coupling apertures  118 ,  120  can extend along a plane that is substantially perpendicular to the lower surface  106  and the upper surface  116 . In one embodiment, the plurality of lower coupling apertures  118 ,  120  can extend from the upper surface  116  to the lower surface  106 . Alternatively, the plurality of lower coupling apertures  118 ,  120  can extend a fixed distance between the upper surface  116  and the lower surface  106 . In one embodiment, the plurality of lower coupling apertures can be threaded. Lower portion  102  can also have a generally arcuate lower clamping feature  122  that extends along a plane substantially parallel to the upper surface  116 . In one embodiment, the lower clamping feature  122  can have a lower relief portion  124 . In one embodiment, the lower relief portion  124  can have an arcuate shape. 
         [0022]    Upper portion  104  can have a mounting surface  126 . Mounting surface  126  can be shaped to couple to upper surface  116  of the lower portion  102 . In one embodiment, mounting surface  126  can be substantially flat to couple flush to upper surface  116 . Upper portion  104  can have a plurality of upper coupling apertures  128 ,  130  that can extend along a plane that is substantially perpendicular to the mounting surface  126 . Upper coupling apertures  128 ,  130  can be positioned to align with lower coupling apertures  118 ,  120  to allow for a fastener to be inserted through upper coupling apertures  128 ,  130  and respective lower coupling apertures  118 ,  120 . Upper coupling apertures  128 ,  130  can have the same diameter of lower coupling apertures  118 ,  120 . Alternatively, upper coupling apertures  128 ,  130  can have a slightly larger diameter than lower coupling apertures  118 ,  120  to allow for production tolerances. In one embodiment, upper coupling apertures  128 ,  130  may have about a 5% to about a 20% larger diameter than lower coupling apertures  118 ,  120 . Upper portion  104  can have a generally arcuate upper clamping feature  132  that extends along a plane substantially parallel to the mounting surface  126 . Upper clamping feature  132  can have an upper relief portion  134 . In a preferred embodiment, the upper clamping feature  132  can mirror the lower clamping feature  122 . 
         [0023]    When the lower portion  102  and upper portion  104  are coupled, the lower clamping feature  124  and the upper clamping feature  134  can form a generally circular clamping aperture  136 . In some embodiments, when lower portion  102  and upper portion  104  are coupled, they can form a plurality of side relief features  138 ,  140 . Side relief features  138 ,  140  can positioned at about ninety-degrees from the lower relief feature  124  and the upper relief feature  134 , although other positions are contemplated. 
         [0024]    Turning now to  FIG. 2 , a magnified view of the clamping aperture  136  can be seen. Clamping aperture  136  can receive a power component  200 . In one embodiment, the power component  200  can be cylindrical in shape. In a specific embodiment, the power component  200  can be a capacitor. Generally, the clamping aperture  136  can be contoured to receive a power component. Capacitors, including power capacitors, can come in a variety of sizes. In one embodiment, the power component clamping device  100  can clamp capacitors having a diameter of about 22 mm to about 35 mm. However, the clamping apertures can be size to accommodate capacitors having diameters less than 22 mm and more than 35 mm. Additionally, the power component clamping device  100  can clamp any type of cylindrical capacitor. Further, it should be known that the representations of capacitors shown in the various figures are for illustrative purposes only and should not be considered limiting. 
         [0025]    Continuing with  FIG. 2 , the power component  200  can be seen located in the clamping aperture  136  between the lower portion  102  and the upper portion  104 . In one embodiment, the power component  200  can be partially or completely surrounded by a dielectric insulator  202 . In one embodiment, the dielectric insulator  202  can be an adhesive tape that surrounds power component  200 . Alternatively, the dielectric insulator  202  can be a dielectric film, such as a polyimide film that can be applied to the power component  200 . The dielectric insulator can have a thickness of about 1 Mil to about 5 Mils, or more or less. The dielectric insulator  202  can have an electrical insulation rating of about 600 volts to about 1000 volts. However, in certain applications, the dielectric insulator  202  may require an electrical insulation rating of more than 1000 volts. 
         [0026]    The power component  200  can also be surrounded by a conformable, thermally conductive material, such as thermal pad  204 . Thermal pad  204  can be used to prevent air gaps between the power component  200  and the power component clamping device  100  to maximize thermal conductivity. Thus, thermal pad  204  can be used to efficiently transfer heat from the power component to the clamping device  100 . In one embodiment, thermal pad  204  can have a thermal conductivity of about 1.0 W/m-k, or more or less. Thermal pad  204  can have a thickness of about 0.508 mm to about 6.350 mm, or more or less. In a preferred embodiment, the thermal pad  204  can have a thickness of about 2.0 mm. Thermal pad  204  can have an adhesive like tack on one or both sides for reducing movement of the thermal pad  204  once put into place. Alternatively, thermal pad  204  can be attached to a power component  200  using an adhesive applied to the thermal pad  204  and power component  200 . In other embodiments, the thermal pad  204  can be held in place by compressing the thermal pad  204  against the power component  200  in the clamping aperture  136 . Thermal pad  204  can have a conformable construction such that compression can be applied to the thermal pad  204  without significant pressure being applied to the power component  200 . Thermal pad  204  can have a flexible structure to allow it to be formed around the power component  200 . 
         [0027]      FIG. 2  shows the thermal pad  204  surrounding power component  200  and compressed by upper portion  104  and lower portion  102 . When thermal pad  204  is compressed, the conformable construction can cause the thermal pad  204  to move and fill in the spaces in the lower relief feature  124 , upper relief feature  134  and side relief features  138 ,  140  of the clamping aperture  136 . Allowing the thermal pad  204  to expand into the plurality of relief features  124 ,  134 ,  138 ,  140  can allow the power component to be secured in the clamping aperture  136  while reducing the pressure placed on the power component from the compression between upper portion  104  and lower portion  102 . This can be critical when attempting to create a thermal connection to an electrical component such as a capacitor without damaging the structural integrity of the device. 
         [0028]    Returning briefly to  FIG. 1 , the clamping aperture  136  can have a diameter which can be about 5% to about 10% larger than the diameter of the power component  200  that is to be located in the in the clamping aperture. However, clamping aperture  136  diameter can be more than 10% or less than 5% of the diameter of the power component  200  as needed. Upper relief aperture  134  and lower relief aperture  124  can each have a diameter of about 30% to about 40% of the diameter of the power component  200 . Side relief apertures  138 ,  140  can have a diameter of about 50% to about 60% of the diameter of the power component  200 . 
         [0029]    Turning now to  FIG. 3 , a multiple power component clamping device  300  can be seen. The multiple power component clamping device  300  has a lower portion  302  and an upper portion  304 . Lower portion  302  can include a plurality of generally arcuate lower clamping features  306 ,  308 ,  310 ,  312 . Upper portion  304  can include a plurality of substantially actuate upper clamping features  314 ,  316 ,  318 ,  320 . Lower portion  302  can have a plurality of coupling apertures  322 ,  324 ,  326  that extend along a plane that is substantially perpendicular to a lower mounting surface  328 . Upper portion  304  can have a plurality of upper coupling apertures  330 ,  332 ,  334  which can extend along a plane that is substantially perpendicular to the mounting surface  336 . Upper coupling apertures  330 ,  332 ,  334  can be positioned to align with lower coupling apertures  322 ,  324 ,  326  to allow for a fastener to be inserted through upper coupling apertures  330 ,  332 ,  334  and respective lower coupling apertures  322 ,  324 ,  326 , to couple the lower portion  302  to the upper portion  304 . 
         [0030]    When the lower portion  302  and upper portion  304  are coupled, the lower clamping features  306 ,  308 ,  310 ,  312  and the upper clamping features  314 ,  316 ,  318 ,  320  can form a plurality of substantially circular clamping apertures  338 ,  340 ,  342 ,  344 . Each of circular clamping apertures  338 ,  340 ,  342 ,  344  can each include a lower relief feature, an upper relief feature, and side relief features as shown in  FIG. 1 . Further, clamping apertures  338 ,  340 ,  342 ,  344  can be dimensioned similarly to the single clamping aperture  136  of  FIG. 1 . While the multiple power component clamping device  300  is shown in  FIG. 3  to have four clamping apertures  338 ,  340 ,  342 ,  344 , it should be known that the disclosed multiple power component clamping device  300  can have more than four clamping apertures or less than four clamping apertures. 
         [0031]    Another embodiment of a power component clamping device can be seen in  FIG. 4 .  FIG. 4  shows an integrated heat sink clamping device  400 . In this embodiment, a lower clamping portion  402  can be integrally formed into a heat sink assembly  404 . In one embodiment, the lower clamping portion  402  and the heat sink assembly  404  can be cast into a single assembly. In an alternate embodiment, the lower clamping portion  402  and the heat sink assembly  404  can be machined to form the integrated heat sink clamping device  400 . In one embodiment, the heat sink clamping device can be constructed using an aluminum alloy. While various types of materials can be used in the construction of the heat sink clamping device, materials should be selected with sufficient thermal resistance to dissipate the heat generated by the power components. In a preferred embodiment, the heat sink clamping device  402  should have a thermal resistance (measured between a power component and where the lower clamping portion  402  meets the heat sink assembly  404 ) of 1° C./W or better. 
         [0032]    The heat sink  404  can have a plurality of fins  406  for increasing the surface area of the heat sink  404  and thereby increasing the thermal efficiency of the heat sink. In some embodiments, the clamp and heat sink can dissipate up to twice the amount of the heat generated in the capacitors compared to free convection cooling. This can eliminate the need for active cooling (e.g. forced air movement) of the power components. While heat sink  404  shows a straight finned heat sink design, other types of heat sink designs can be used in the heat sink clamping device  400 . For example, pin, flared, or other fin designs can be used as applicable. 
         [0033]    Heat sink clamping device  400  can have a plurality of openings  408 ,  410 ,  412 ,  414  for coupling the heat sink clamping device  400  to a separate structure. In one embodiment, the separate structure can be an electrical enclosure. Alternatively, the separate structure could be a piece of equipment or machine. The heat sink clamping device  400  can further have a substantially flat mounting surface  416  for providing a flush fit with a separate structure. In one embodiment, a gasket (not shown) can be applied to the substantially flat mounting surface  416  to provide a seal between the heat sink clamping device  400  and a separate structure. The gasket can be a formed gasket, such as those made of rubber or foam type materials. Alternatively, the gasket can be in the form of a liquid gasket such as silicon. The gasket can be selected to achieve a specific environmental rating. In one embodiment, gasketing can be used to achieve a NEMA 4/4× environmental rating. 
         [0034]    The lower clamping portion  402  can be integrally formed into the heat sink clamping device  400  as shown in  FIG. 4 . The lower clamping portion  402  can have a plurality of lower clamping features  418 ,  420 ,  424 ,  424 . In one embodiment, the lower clamping portion  402  may have four clamping features; however, it should be known that the lower clamping portion  402  can have more than four clamping features or less than four clamping features. Lower clamping portion  402  can have a plurality of substantially flat mating surfaces  426 ,  428 ,  430 ,  432 . Mating surfaces  426 ,  428 ,  430 ,  432  can be sized to mate with corresponding mating surfaces on an upper clamping portion discussed later. One or more of the mating surfaces  426 ,  428 ,  430 ,  432  can have one or more lower coupling apertures  434 ,  436 . In one embodiment, the lower coupling apertures can be threaded. Alternatively, the one or more mating surfaces  426 ,  428 ,  430 ,  432  can have other coupling mechanisms, such as threaded rods, tongue and groove features, etc. 
         [0035]    Turning to  FIG. 5 , a cut-away view of the heat sink clamping device  400  can be seen. An upper coupling portion  502  can be coupled to lower clamping portion  402 . Upper coupling portion  502  can have a plurality of upper clamping features  504 ,  506 ,  508 ,  510 . The upper clamping portion  502  can have a number of upper clamping features that correspond to the number of lower clamping features on the lower clamping portion  402 . Upper clamping portion  502  can have a plurality of substantially flat mating surfaces  512 ,  514 ,  516 ,  518  that correspond to mating surfaces  426 ,  428 ,  430 ,  432  on the lower coupling portion  402 . One or more of the mating surfaces  512 ,  514 ,  516 ,  518  can have one or more upper coupling apertures  520 ,  522 . In one embodiment, the upper coupling apertures  520 ,  522  can be threaded. Alternatively, the one or more mating surfaces  512 ,  514 ,  516 ,  518  can have other coupling mechanisms, such as threaded rods, tongue and groove features, etc. 
         [0036]    When the lower portion  402  and upper portion  502  are coupled, the lower clamping features  418 ,  420 ,  422 ,  424  and the upper clamping features  504 ,  506 ,  508 ,  510  can form a plurality of substantially circular clamping apertures  524 ,  526 ,  528 ,  530 . Each of circular clamping apertures  524 ,  526 ,  528 ,  530  can each include a lower relief feature, an upper relief feature, and side relief features as shown in  FIG. 1 . Further, clamping apertures  524 ,  526 ,  528 ,  530  can be dimensioned similarly to the single clamping aperture  136  of  FIG. 1 . 
         [0037]      FIG. 5  further shows a power component  532  located in clamping aperture  528 . Power component  532  is surrounded by thermal pad  534 . This provides an exemplary illustration of clamping a power component  532  using the heat sink clamping device  400 . 
         [0038]    The power component  532  can be clamped into the heat sink clamping device  400  using a variety of methods. In one preferred method, the power component  532  is first wrapped with a di-electric tape (not shown) and then further surrounded by the thermal pad  534 . The power component  532  can then be placed into a lower clamping feature  422  of the lower clamping portion  402  such that the thermal pad  534  contacts the lower clamping feature  422  for the length of the power component  532 , or a portion thereof. This step can be repeated for each power component  532  that is installed in the lower clamping portion  402 . Once all of the power components  532  are placed in the lower clamping portion  402 , the upper clamping portion  504  can be coupled to the lower clamping portion  402 . In one embodiment, fastening devices can be used to couple the lower clamping portion  402  to the upper clamping portion  504  extending through the upper coupling apertures  520 ,  522  and into the lower coupling apertures  434 ,  436 . The heat sink clamping device  400  can then be coupled to a separate structure. 
         [0039]    In use, the heat sink clamping device  400  can be used to improve cooling in electrical enclosures. In one example, the heat sink clamping device  400  can be used to cool power components such as bus capacitors in an enclosed variable speed drive application. Additionally, modular enclosures, those allowing portions of an industrial control system to be positioned near to the equipment or processes they control, can specifically benefit from heat sink clamping device  400 . One such system, for example, is the Rockwell Automation ArmorStart product line. These modular enclosures can contain industrial control components such as controllers, variable speed drives, motor starters, etc., which can all generate heat. Additionally, these types of modular enclosures can be sealed against outside contaminates to various degrees. For example, modular enclosures can be constructed with NEMA, or equivalent, ratings such as NEMA 3× or NEMA 4/4R. The heat generated by the internal industrial control components can be difficult to dissipate in a sealed enclosure; particularly power electrical power components, such as those found in a variable frequency drive. For example, power components such as the bus capacitors in a variable speed drive can put off significant heat that requires dissipation. Failure to effectively cool these components can reduce their effective life. To increase the efficiency in dissipate heat from components in sealed modular enclosures, active cooling devices, such as stirring fans, can be used to provide airflow over components to remove heat. However, stirring fans, and fans in general, are susceptible to malfunctions. However, the heat sink clamping device  400  can be used to more efficiently remove heat from these power components, and can thereby reduce or eliminate the need for active cooling devices, such as stirring fans. 
         [0040]    This description uses examples to disclose the invention and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 
         [0041]    To apprise the public of the scope of this invention, the following claims are made: