Abstract:
A heat-exchanging mat to cool livestock provides for elastic water conduction channels displaced toward an upper surface of the mat and provides for cushioning placed below those elastic channels. In this way, a high degree of cushioning may be obtained without sacrificing an efficient transfer of heat into the upper surface of the mat.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. provisional application No. 61/838,682 filed Jun. 24, 2013 and hereby incorporated by reference. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    The present invention relates to an apparatus for cooling livestock and in particular to an improved heat exchanger providing a stall mat. 
         [0003]    A heat-stressed cow exhibits physiological reactions and abnormal behavior such as standing up and thermal panting (both of which indicate an increased respiratory rate and a higher than normal body temperature). The cow will also eat less and drink more water. These reactions cause serious side effects: the cow will produce much less milk, become less fertile and suffer higher rates of debilitating diseases such as mastitis and lameness. 
         [0004]    To protect cows from excessive heat, dairy farmers typically employ cooling systems that spray water directly onto the cows and rely on either overhead fans equipped with mister nozzles to promote evaporation of that water, or wide-body housing barns equipped with evaporative cooling pads and fans. However, these approaches achieve limited success in humid climates and can pose problems in hot regions where water is scarce. 
         [0005]    An alternative approach to cooling cows involves using a heat exchanger positioned beneath the bedding material or under a cushion in the stall. The heat exchanger provides a set of conduits through which chilled water can be circulated, and the bedding material protects the conduits and provides the cushioning necessary to avoid further discomforting cows that are lame that may otherwise deleteriously modify their resting behavior. 
       SUMMARY OF THE INVENTION 
       [0006]    The present inventors have determined that, due to its thermal resistance, the thickness of a bedding material (such as sand or compost) that is placed over a heat exchanger to mitigate lameness substantially impedes the conduction of heat from the cow. The present invention solves this problem by using a heat exchanger that is equipped with elastic water conduction channels and may be positioned above the cushioning. Consequently, the cold water in the exchanger will be in direct contact with the resting cow, perhaps separated from the cow by only a relatively thin elastic sheet, for example, and any necessary cushioning can be installed beneath the water channels. 
         [0007]    One version of the invention features a heat exchanger that has an elastic mat with an upper surface sized to substantially support a reclining dairy cow. The elastic mat incorporates at least one elastic channel and includes at least one inlet that connects to the mat (and has been adapted to connect to a water supply line) and at least one outlet that connects with the mat (and has been adapted to connect to a water drain line). The elastic channel(s) have been adapted to conduct water from the one inlet(s) to the outlet(s) beneath the surface over an area substantially greater than the contact area of a dairy cow to cool a dairy cow reclining on the elastic mat, and the elastic mat has been adapted to deform upon contact with the claws (a cow hoof is cloven into two parts called claws) of a rear hoof of a cow standing up from a lying position on the elastic mat to distribute forces over the entire hoof. 
         [0008]    Thus at least one version of the invention features cushioning material placed beneath the channel(s) where the material will not interfere with heat transfer. The elastic channels transmit the weight of the cow to the cushioning lower layer. At least one other version of the invention features a heat exchanger that is cushioned to either prevent or mitigate hoof lameness, thereby reducing or eliminating the need for any bedding that may reduce heat-transfer efficiency. 
         [0009]    The elastic mat may have an area of greater than 1 m 2 . 
         [0010]    Thus, at least one version of the invention features a cooling interface that can provide a sufficient amount of heat exchange over the entire contact area of a typical resting cow. 
         [0011]    The portion of the elastic mat beneath the channels with respect to the surface may be thicker than a portion of the elastic mat above the channels with respect to the surface before deformation by a cow reclining on the elastic mat. 
         [0012]    Thus at least one version of the invention features a mechanism for ensuring cushioning of sufficient thickness to mitigate hoof injury and deter modification of resting behavior without increasing the thermal resistance that exists between the water channels and the cow. With the channels positioned at the top of the mat, additional cushioning will not affect heat transfer. 
         [0013]    The material of the elastic mat may separate channel(s) from the surface by providing an average thermal resistance of less than 0.04 K/W between the water in the channel and the surface over the contact area. 
         [0014]    Thus at least one version of the invention minimizes the adverse effect that any cushioning material may have on heat transfer. 
         [0015]    A sheet material of less than 4 mm in thickness may separate the channel(s) from the surface. 
         [0016]    Thus at least one version of the invention features an upper material that is thin enough to alleviate any significant concern about the material&#39;s thermal resistivity yet thick enough to adequately resist damage, 
         [0017]    The elastic mat may have a continuous upper surface. 
         [0018]    Thus at least one version of the invention features a heat exchanger system that is easy to clean and maintain. 
         [0019]    To prevent the condensation that can form on the elastic surface under various microclimate conditions, a temperature control unit may be added. 
         [0020]    With respect to the remainder of the elastic mat, the upper layer defining the surface may have reduced elasticity in some dimensions. In one version, the upper layer may provide an elastomer (incorporating fibers with lower elasticity than an elastomer of the upper layer). 
         [0021]    Thus at least one version of the invention features a mat with force-spreading ability so that the cushioning effect of the mat will be adequate both when the cow&#39;s weight is spread over the entire surface and also during point loading under the cow&#39;s rear hooves when the cow attempts to rise. 
         [0022]    The elastic mat may be comprised of a closed-cell, elastomeric foam, the inner portion featuring upwardly open troughs defining the channel(s) covered by a substantially continuous solid cell-free elastomeric sheet. 
         [0023]    Thus at least one version of the invention provides a simple method for manufacturing the elastic channels that does not interfere with cushioning. 
         [0024]    The mat may provide at least two zones, each with a different elasticity, one zone adapted to support the rear quarters of a cow reclining on the elastic mat and a second portion of the elastic mat lying outside of the first portion. 
         [0025]    Thus at least one version of the invention features special properties at the rear of the mat to help reduce the risk of causing a modified resting behavior caused by rear-hoof lameness. A cow when rising will first gather its hind quarters and in doing so may place additional pressure on the outer surfaces of the claws of the rear hoof 
         [0026]    The mat may provide at least a first zone adapted to support rear quarters of a cow reclining on the elastic mat and a second zone, outside of the first, wherein the first includes a greater density of channels. 
         [0027]    Thus, for more efficient operation, at least one version of the invention features a heat exchanger system that tailors heat-exchanging properties to suit different anatomical regions of the cow. 
         [0028]    The heat exchanger may provide multiple elastic channels that conduct water through different yet parallel paths from at least one inlet to at least one outlet. 
         [0029]    Thus at least one version of the invention reduces the pressure drop and the temperature increase that occur when water passes through the mat, and water supply lines of greater length and mats can be optimally linked in series and parallel. 
         [0030]    The multiple elastic channels intersect each other at multiple locations to form a network. 
         [0031]    Thus at least one version of the invention features a system for distributing water along multiple channels to produce a more evenly distributed cooling effect. 
         [0032]    The periphery of the elastic mat may feature tabs adapted to receive fasteners that secure the mat to a concrete stall floor. 
         [0033]    Thus at least one version of the invention enables it to be stabilized in a concrete cow stall. 
         [0034]    A system of mats may be arranged either in series or in parallel where at least one outlet from a preceding mat connects with at least one inlet of a succeeding mat in the series so that water can flow from one mat to the next and thus pass through all the mats in the series. 
         [0035]    Thus at least one version of the invention features a cost-effective water delivery system in which cooling water may be shared among mats. 
         [0036]    The mats may be used by circulating water from the inlet to the outlet to provide for a heat transfer in excess of 500 W between a cow reclining on the elastic mat and the conducted water. 
         [0037]    Thus at least one version of the invention features a heat exchanger system that may substantially eliminate the need for evaporative pads, water sprayers and fans and their associated environmental burden. 
         [0038]    The elastic mat and an insulating layer may be placed on a concrete slab that is substantially free of sand or compost, and it may be exposed on its upper surface and in direct contact with a cow. 
         [0039]    Thus at least one version of the invention eliminates the hygienic and disposal problems associated with loose bedding (and especially sand, which can interfere with or damage manure handling equipment). 
         [0040]    These particular objects and advantages may apply to only those versions of the invention that fall within the claims and thus do not define the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]      FIG. 1  is a perspective view of a mat constructed according to the specifications of the present invention and showing the connected input and output lines and anterior and posterior zones with respect to a cow&#39;s typical orientation; 
           [0042]      FIG. 2  is a top plan cross-section of the mat shown in  FIG. 1  and depicts the different channel configurations for the anterior and posterior zones; 
           [0043]      FIG. 3  is a fragmentary cross-section along line  3 - 3  of  FIG. 2  and shows a closed-cell foam body with incised channels covered by a solid rubber sheet (in accordance with one embodiment of the invention); 
           [0044]      FIG. 4  is a diagrammatic cross-section similar to that shown in  FIG. 3  and depicts the “tenting” support that is provided to the outer rear claw of the hoof whenever the cow rises; 
           [0045]      FIG. 5  is a top-plan fragmentary representation of the fibers dispersed throughout the top rubber sheet to reduce tensile stretching; 
           [0046]      FIG. 6  is a simplified diagram of the force-versus-compression distance for the weight of a typical cow (without “bottoming out” against concrete slab); 
           [0047]      FIG. 7  is an exemplary block diagram showing multiple pads interconnected in series to a source of chilled water. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0048]    Referring now to  FIG. 1 , a heat exchanger system  10  according to the present invention may provide for a generally planar rectangular elastic mat  12  having a substantially continuous upper surface  14 , and in one example having an area of approximately 4 feet in width and 6 feet in length and a vertical thickness of 2 to 4 inches. In some embodiments, the mat  12  provides an area that can substantially fully support a reclining cow. 
         [0049]    Water inlet lines  16  are attached to a superior end  18  of the mat  12  to introduce water into a superior region  19  of the mat  12 , the superior region  19  intended to be positioned under the front quarters of a cow  25  lying on the mat  12 . Corresponding water outlet lines  20  are attached to a left side of the inferior end  22  of the mat  12  near an inferior region  21 , the latter intended to be positioned under the hindquarters of the cow  25 . Each of the water inlet lines  16  and water outlet lines  20  connect, through a mat sidewall  24 , with the interior of the mat as will be described. 
         [0050]    Mounting tabs  26  may extend from lower edges of the sidewalls  24  of the mat  12  to receive mounting hardware  28  (a washer and headed fastener, for example) for attaching the mat  12  to a concrete slab  29  or the like. During use, the slab  29  and the mat  12  may be substantially free of other bedding materials including sand. 
         [0051]    Referring now to  FIG. 2 , the water inlet lines  16  deliver water  30  into a set of channels  32  located inside the mat  12  and separated by divider walls  33 . In the superior region  19 , the channels  32  are generally parallel along an inferior-superior axis and extend from the superior end  18  for about two thirds the length of the mat  12 . The water inlet lines  16  may be attached to a manifold  17  dividing the introduced water  30  outside of the mat  12  so that the water will enter various different channels  32  along the width of the superior end  18  to provide a substantially even water flow in an inferior-superior direction through the various channels  32 . 
         [0052]    At the end of the channels  32  within the mat  12 , a diverter wall  34  may channel the water to a right side of the mat  12  and into a channel network  36  at the inferior region  21  occupying the final third of the mat  12 . This channel network  36  provides a mesh of channels  37  separated by pillars  38  arranged in rows and columns aligned with the height and width of the mat  12  and thus providing a diffuse flow of the water from the right side of the inferior end  22  to the left side of the mat  12 , where it is received by the outlet lines  20 , and also through a manifold  23  that provides multiple outlets spaced along the left side of the inferior end  22  of the mat  12 . 
         [0053]    The channels  32  and  37  are otherwise fully surrounded by a skirt wall  40  that serves to retain water flow within the mat  12 . 
         [0054]    Referring now to  FIG. 3 , each of the channels  32  and  37  (the latter not shown in  FIG. 3 ) may be formed by grooves cut or molded in the upper surface of a closed-cell elastomeric foam material  42  with the walls  33  and pillars  38  (the latter not shown in  FIG. 3 ) and the skirt wall  40  constructed of the elastomeric foam material  42  itself. Suitable elastomeric foam materials  42  include a closed-cell foam material available from Foxworthy Supply Inc. of Michigan USA under the trade name of Foamat™. The channels  32  and  37  may be approximately 1 inch deep, and the mat will typically have a thickness ranging from 1 inch to 3 inches in depth. 
         [0055]    The upper surface of each groove forming channels  32  or  37  may be covered by a solid rubber-like sheet material  44  (as will be described further below) to seal water  30  within channels  32  or  37 . In one embodiment the solid sheet material  44  will be approximately 2 mm thick and, preferably, will range from 1 mm to 4 mm in thickness to provide resistance against tearing while ensuring a relatively low thermal resistance. More generally, the material of the sheet  44  will be selected according to its elastic flexibility and its ability to comport with the desired cushioning of the mat 1.2 and its ability to provide an average resistance of less than 0.04 Kelvin per watt (and preferably less than 0.02 Kelvin per watt) between the water  30  in the channels  32  and  37  across the entire area in contact with the cow  25  (approximately one square meter on average). In this way, with respect to water typically chilled (approximately) to 15 degrees Celsius or 60 degrees Fahrenheit, a heat transfer in excess of 500 watts (and preferably in excess of 1000 watts) may be achieved between the cow  25  and the water  30 . Suitable materials include a 2 mm rubberized to/woven back cover commercially available under the trade name of MC2 Cow Mat Trop Cover from North Brook Farms of Auburn, N.Y., USA. This material has a thermal conductivity of approximately 0.1 W/m-K. 
         [0056]    In one embodiment, the channel density in the inferior region  21  (that is, the ratio of the upper surface area of channels  32  or  37  per area of the mat  12 ) is made greater than in the superior region  19  to provide increased heat transfer from the inferior anatomy of the cow  25  including the udder. 
         [0057]    It will be understood from  FIG. 3 , that channels  32  and  37  are proximate to the upper surface of the mat  12 , which will be in closest contact with the cow  25  and that the bulk of the cushioning provided by the mat  12  is displaced behind or below the channels  32  or  37  in a supporting region  50  at the bottom of the mat  12  being generally equal to or greater than the height of the channels. By providing channels  32  and  37 , which are substantially elastic (because of the elasticity of the walls  33  and pillars  38 ), the cushioning of region  50  need not be interposed between the cow  25  and the water  30 , such as would reduce heat flow, but can instead operate through channels  32  and  37 . 
         [0058]    Referring now to  FIGS. 2 and 4 , it should be noted that the cumulative cushioning effect provided by the foam material  42  in the supporting region  50  and the foam material forming the walls  33  and pillars  38  in the inferior region  21  will be softer than the cushioning provided by the same structures existing in the superior region  19 , and also that this is a result of the reduced areal density of walls  33  in the superior region  19  compared to pillars  38  in the inferior region  21 . “Softer” in this context means a lower effective spring constant, one that allows greater deformation in reaction to a given amount of force. This softer cushioning provides greater force to be spread to the claws of the cows hoof  54 , which typically experience higher forces when the cow  25  stands up. By reducing the point-of-contact forces, the mat may reduce the risk of modified resting behavior and resulting lameness or exacerbation of lameness. 
         [0059]    Referring also to  FIG. 5 , sheet material  44  may include woven or nonwoven fibers  56  that tend to reduce the elasticity of the sheet material  44  in directions parallel to its broad surface. As shown in  FIG. 4 , a result is that pressure exerted by the hoof  54  causes the sheet material  44  to envelope to some degree the claws of the hoof  54  and produce a tenting across multiple pillars  38  that tends to stiffen the cushioning with increased reflection, thus preventing a “bottoming out” of the hoof  54  against the slab  29 . 
         [0060]    Referring more generally now to  FIG. 6 , the elasticity of the combined cushioning of foam material  42  in region  50  of the mat  12  and of the walls  33  and pillars  38  is adjusted so that any given force  57  expected to be exerted by a full-grown cow  25  over the area of the hoof  54  will provide a compression  58  of the mat  12  that is less than a compression that would reach the force asymptote  60  near where the Hooke&#39;s relationship  62  of spring materials breaks down because of a full compression of the material. Generally, the tenting action will provide a somewhat stiffer response  64  than would be provided by only the spring alone for high deflections and a stiffness comparable to only the spring for lower deflections. In this respect, the mat  12  may be suitable for cushioning the broad area of the cow  25  as well as the points-of-contact of the hoof  54 . 
         [0061]    Referring now to  FIG. 7 , multiple mats  12   a - 12   c  may be connected to a single supply system  65  providing, for example, chilled water from a source (either an aquifer  66  or a conventional closed-cycle refrigeration system  68 ). Water chilled to a temperature ranging from 40 to 70 degrees Fahrenheit may be pumped (by pump  73 ) to be received at a first mat  12   a  through the inlet lines  16  of that mat  12   a.  Water passing out of mat  12   a  through the outlet lines  20  may then be fed to the inlet lines  16  of mat  12   b . In a similar manner, water may pass from mat  12   b  to mat  12   c  and from there to mat  12   d . 
         [0062]    Water exiting through outlet lines  20  of mat  12   d  may pass back to a discharge line  74  and either back into the aquifer or into the heat exchanger of a closed-system refrigeration unit. 
         [0063]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper,” “lower,” “above” and “below” refer to directions in the drawing to which a reference is made. Terms such as “front,” “back,” “rear,” “bottom” and “side” describe the orientations of portions of a component within a consistent but arbitrary frame of reference that is made clear by reference to the text and the associated drawings describing any component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and/or words of similar import. Similarly, the terms “first” and “second,” and other such numerical terms referring to structures, do not imply a sequence or order unless clearly indicated by explicit statement or context. 
         [0064]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a,” “an,” “the” and “said” are intended to mean that one or more of such elements or features exist. The terms “comprising,” “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is also to be understood that the methodical steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order either discussed or illustrated, unless an order of performance is specifically identified. It is also to be understood that additional or alternative steps may be employed. 
         [0065]    It is specifically intended that the present invention will not be limited to the embodiments and illustrations contained herein and that the claims herein should be understood to include modified forms of the invention&#39;s various embodiments including portions of the embodiments and combinations of elements of different embodiments as would come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications are hereby incorporated herein by reference in their entireties.