Abstract:
The invention relates to a method and device for preserving snow. A cooling mat device ( 2 ) is laid out on predetermined areas of a subbase ( 1 ) on which snow should be preserved. A coolant is fed to said cooling mat device via a coolant supply line ( 21 ), and the coolant is removed via a coolant return line ( 22 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a process and a device for making snow durable. 
     2. Description of the Related Art 
     Critical points on ski runs, such as e.g. overloaded and narrow downhill areas, south-slope areas, and areas with valley slopes, are generally covered with artificial snow, in order to be able to ensure a longer skiing season. One problem in this is an extremely high consumption of water. Generally, the water required for producing artificial snow is stored in water reservoirs and pumped to the individual snow guns with the aid of pumps. When artificial snow generated in this way melts, large quantities of water are formed, which flow down the mountainsides, drain away, and are thus lost. Another problem consists of the fact that when covered with artificial snow, the environment is damaged significantly. This is due especially to the fact that artificial snow flows more slowly into the ground and is therefore pushed to the side when traveled on, so that the ground is thus uncovered faster and is therefore damaged. When such partly released ground regions are uncovered, the danger also exits that skiers are injured seriously while skiing. 
     A process for making snow durable is known from printed document U.S. Pat. No. 3,893,507, in which a cooling-mat device is placed directly on a ski slope, not further defined, and then covered with sand or something similar. After that, a layer of artificial show or natural snow is applied to the cooling-mat device. This layer is cooled as needed. There is a problem in this in that the cooling-mat device can be damaged by the ground, especially by traffic, and in addition the vegetation on the ground can be permanently disturbed by the cooled cooling-mat device and the sand layer. Application of the sand layer at the start of the winter season and its removal after the winter season should be so problematical that cooling of ski slopes cannot be realized in the manner described. 
     SUMMARY OF THE INVENTION 
     This task is solved by a process for making snow durable on certain regions of natural ground, by an applied cooling-mat device through which a coolant is fed through a coolant-supply line and removed through a coolant-return line, the cooling-mat device being placed on a snow layer already existing on the natural ground that has previously been leveled with a roller or something similar, and another snow layer being applied to the cooling-mat device, and the snow layers being cooled by the cooling-mat device. 
     This task is solved by a process with the characteristics of patent claim  1  and a device with the characteristics of patent claim  20 . 
     The essential advantage of the present invention is in the fact that by simply placing cooling mats in desired areas a ski run can be achieved that is cooled for artificial or natural snow to the extent that an undesired rapid melting of the natural or artificial snow can be avoided. Since natural or artificial snow can be prevented from rapid thawing in these critical points in a relatively simple way, a significantly longer ski season can be assured. Cross-country and downhill courses especially can be made durable in the manner according to the invention to withstand ski races and similar things, so that such competitions can be held relatively independently of weather conditions. In addition, it is also guaranteed that all skiers encounter the same conditions during such a competition, as far as possible. 
     However, the essential advantage of the present invention consists of the fact that the enormous water consumption associated with the traditional snow gun can be reduced by making the snow durable. Since the mats used in connection with the present invention have lines with a very small diameter, there is only a relatively small need for coolant. 
     An especially preferred embodiment of the invention involves using Glysantin or a similar environmentally friendly coolant, advantageously containing a colorant that indicates the place of a failure in case of a line break. It is then particularly easy to gain access to the failure site for repair, and the line can be clamped off from the system by simple heating and melting, in which case the function of the entire system is essentially maintained. 
     In an especially preferred embodiment, the mat device has input funnels, into which a drilling device can be introduced from the side away from the ground in an especially simple manner and pushed into the ground, so that tilting rods can be inserted later and attached to the ground. 
     Additional advantages and embodiments of the invention can be seen from the subclaims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, the invention and its embodiments will be explained in more detail in connection with the diagrams. 
     Here: 
     FIG. 1 shows a schematic representation to explain the process according to the invention for making snow durable, 
     FIG. 2 shows a cross-section through the mat device used in connection with the invention, and 
     FIGS. 3 through 5 show further developments of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     According to FIG. 1, by to the process according to the invention a cooling mat device  2  is placed on ground  1  on which the snow is to be made durable. The ground  1  involves, for example, an especially critical point of an alpine downhill run that is under a high load, the area of a valley slope of a ski region, an alpine downhill or slalom course, or something similar. The cooling-mat device  2  includes a coolant-supply line  21 , a coolant-return line  22 , and line hoses running between them  23 . The coolant-supply line  21  is fed by a pump  3 , which takes the coolant through a line  4  from a coolant reservoir  5 . From the supply line  21 , the coolant arrives through the hoses  23  at the area to be cooled  1  and finally at the coolant-return line  22  and from there back to the coolant reservoir  5  (line  7 ). The coolant used involves an environmentally friendly coolant, preferably Glysantin. The coolant reservoir  5  and the pump  4  are advantageously attached to a case  6  or a support stand, movable or stationary, and the cooling-mat device  2 , when not needed on the ground  1  can likewise be stored in the case  6 . 
     In order to make the snow on the ground  1  durable, we proceed as follows: After the cooling-mat device  2  has been spread on the ground  1 , coolant is pumped from the coolant reservoir  5  through the supply line  21  and the return line  22  through the line hoses  23 . In this case, the ground  1  and its surface are cooled in the region of the cooling-mat device, for example to a temperature in the range from −3 to −7° C. Because of the humidity of the surrounding air, the cooling-mat device is thereby covered with ice. When artificial or natural snow is applied to the cooling-mat device  2  from above (arrow direction P), this snow is not melted, because of the cooling of the ground  1  and the cooling-mat device  2 , so that no melt water arises, as is the case in the state of the art, and the ground  1  can be traveled on practically as long as the cooling-mat device  2  is operated. If necessary, worsened conditions caused by snow being scraped and pushed away can be compensated by spraying later artificial snow from snow guns. 
     In the embodiment of FIG. 1, in which the supply line  21  and the return line  22  run parallel, an especially uniform cooling of the ground is achieved, since the coolant of the cooled side is returned as coolant to the supply side. 
     In the embodiment illustrated in FIG. 3, in which the supply line  21  and the return line  22  are at a distance from each other corresponding to the length of the lines  23 ′ and run parallel to each other, a double width of the ground  1  can be covered with the cooling device  2 , in which case, however, it must be taken into account that greater warming of the coolant occurs along the lines  23 ′. 
     FIG. 2 shows a cross-section through the present cooling-mat device  2 . According to it, a cooling-mat device  2  is placed on the ground  1 , which may already have a snow layer, consisting of individual hoses  23  connected to the supply line  21  and the supply line  22 . When cooled by the cooling-mat device  2 , a protective layer  8  of snow and ice arises advantageously on the ground  1 , which protects the ground  1  from mechanical damage. Such a protective layer of snow and ice  8  also arise on the surface of the cooling-mat device  2 . The artificial or natural snow  9  is then applied to this protective layer  8 . 
     In the manner shown in FIG. 2, in order to avoid damage to it, funnel devices  10  can be arranged with the system itself on the ground, in order to avoid damage to it, which are inserted through holes between the line hoses  23  or  23 ′. These funnel devices  10  have the form of tubes  101  that have funnel-shaped expansions  102  on the side away from the ground  1 . Since the places of the funnel devices are known, drills can also be inserted into the mat devices  2  from the side away from the ground when it is covered by snow through the expansions  102  and then inserted into the ground  1  automatically through the tube  101 , so that holes can be drilled for attaching tilting rods or similar things without damaging the mat device  2 . 
     When the lines of the line hoses  23  of the system of FIG. 1 have a length of six meters, a width of ground  1  of six meters can be covered with the system. When the supply line  21  and the return line  22  are separated from each other in the manner shown in FIG. 3, a width of ground  1  of twelve meters can be covered. 
     The mat device  2  can be constructed with any desired length, because stopper parts  24  are used at the free ends to close the supply line  21  and the return line  23 . For an extension, these stopper parts  24  are removed, so that additional mat-device parts can be connected to lines  21  and  22 , which, if they are not to be extended in turn and therefore represent only intermediate parts, are then closed by the stopper parts  24 . 
     In connection with FIGS. 4 and 5, which show a longitudinal section and a top view of the mat device  2 , another embodiment is described, in which nap-like projections  30 ,  30 ′ are arranged on the mat device  2 , which are connected from above or below to lines  23  or  23 ′. The nap-like projections  30 ,  30 ′ which project downward or upward from the lines  23 ,  23 ′, are preferably open at the bottom or top, so that snow and/or ice can be captured in them. This brings the advantage that the snow has an even better hold on the mat device. For this reason, the lines  23 ,  23 ′ are better protected from outside effects, such as those cause e.g. by ski edges or run rollers. 
     Advantageously, the nap-like projections  30 ,  30 ′ are attached in the form of strips, in which the projections  30 ,  30 ′ are each connected on the side (in the transverse direction) by means of elements  31  that can be plugged into the lines  23 ,  23 ′ at particular distances on the mat devices  2 . The strips run in the longitudinal direction of the mat device  2  (FIG.  5 ). The elements  31  have advantageously the form of cap parts adapted to the shape of the cross-shaped cross-section of the lines, which are likewise made with a cross shape and can be plugged into the lines  23 ,  23 ′. In this way, the strips with the projections  30 ,  30 ′ can be inserted into the lines  23 ,  23 ′ in the direction transverse to the mat device and can be removed from them at any time. Advantageously, several mat devices can be connected together in the longitudinal direction with strips of this type. 
     The downward projections  30  are used as spacers from the ground and therefore protect the mat device  2  from stones other objects. 
     The projections  30 ,  30 ′ can also serve to attach the mat device  2  to the ground, in which case holding elements, advantageously in the form of needles  32  or prongs can be driven into the ground through the upward and downward projections  30 ,  30 ′ or only through the downward projections  30 . 
     The strips with the projections  30  or  30 ′ consist advantageously of plastic, which can be reinforced with metal inserts. 
     The downward projections  30  and the upward projections  39 ′ can be attached to each other by means of plug connections  33 . 
     When the lines  23  are made into loops, the strips are appropriately each attached to only one line  23  of a loop, in which case the other line of the loop is placed advantageously between two adjacent upward projections  30 ′. 
     With the present mat devices, a number of objects can be formed from snow or ice, because of their flexibility. In particular, so-called “half pipes” or similar land formations can be made for snowboarding and jumps can be constructed for trick skiing or ski flying. In this ways, the best conditions can be created for these kinds of sports, even in less favorable regions in a relatively small space. It is likewise possible to made sculptures and all kinds of objects of snow or ice durable for longer periods of time; this can also be possible in enclosed spaces or in regions with warm or hot climates (e.g. ski jumps in pedestrian zones of cities, “half pipes” on the beach, igloos in the desert, etc.). 
     In the following, especially preferred processes for making snow durable with the present cooling-mat devices  2  will be explained. 
     When a cooling-mat device  2 , consisting of several cooling-mat parts, is placed on ground  1  that is already covered with a snow layer, a run roller or another clearing device first pushes snow layer with a depth of, for example, 30 cm from away from an existing surface of the ground  1 , so that a smoothed surface arises, onto which the cooling-mat parts of the cooling-mat device  2  are placed and connected through flexible plastic hoses to the coolant reservoir  5 . 
     Artificial snow can then be sprayed by snow guns onto the cooling-mat device  2  that has been placed in the regions or snow can be applied from the edge of the cooling-mat device  2  with the aid of the run roller. In the latter case, care must be taken that the cooling-mat device  2  is not cooled before the run roller is used, since the individual cooling-mat parts could break when the run roller is used. 
     With the installation method described above, a relatively large snow surface can be made durable on the ground  1  advantageously within a short time. This procedure is especially recommended in the spring (February through April), when individual regions of the run thaw due to strong solar radiation and heating to the ground  1 , or snow can be made temporarily durable on park areas or similar places while large events are being held. 
     A procedure in which a snow layer is applied with the cooling-mat parts on ground  1  already covered with a snow layer in connection with to a cooling-mat device  2  is especially advantageous. If warm coolant, heated for example to about 20 to 60° C. in the coolant reservoir  5 , is then fed through the cooling-mat device  2 , the individual cooling-mat parts are warmed, so that they sink into the snow layer already present on the ground  1 . Advantageously, the individual warm cooling-mat parts are elastic when stepped on or when a run roller is used, so that they do not break. When the external temperature is very cold, this can be achieved through a better connection between the snow and the cooling-mat device  2  by melting. 
     At the end of the winter season, the cooling-mat devices can be warmed up in the manner described above, for example to 40° C., so that they melt out of the snow, become elastic thereby, and are cleaned at the same time. In this case, it is advantageous that no ice layers are formed when the snow melts. From the point of view of environmental protection, this corresponds to a natural thawing. 
     It is especially advantageous if the connections from one individual cooling-mat parts to another and the connections to the coolant reservoir  5  are made of flexible plastic hoses. A complicated and cost-intensive welding of the cooling-mat parts to each other is therefore not required. Instead, the individual cooling-mat parts are connected to each by a plug process. If the flexible plastic hoses are transparent, there results the advantage that are accumulations become visible from the outside, so that a faultless cooling operation can be assured. 
     The artificial plastic-hoses can be rolled up appropriately, and they can therefore be rolled out on site from these hose rolls. This brings a significant space savings in transportation and storage. Likewise, flexible plastic hoses can be used to repair damaged line in the cooling-mat parts. 
     Advantageously, in order to increase the flexibility of the process, the hose connections between the coolant reservoir  5  and the supply and return lines  21 ,  22  are made with so-called check-valve connections, as are known for example from garden-watering system. By this means, it can be assured that the connection to the coolant reservoir  5  can be made or broken within seconds, without the coolant coming out of the supply line  21  or the return line  22 . 
     In connection with the process according to the invention, it is especially important that cooling of the cooling-mat device  2  must be made only temporarily. For example, the connection between the cooling-mat device  2  and the cooling reservoir  5  can be turned off after the cooling-mat device  2  has been cooled initially, advantageously for about 24 hours, with a coolant at about −11 to −20° C. Even with fairly strong solar radiation, as appears especially in the months of March and April, no great changes are to be expected over four to five days. The hard-snow layer of about 20 to 40 cm formed during the cooling is adversely affected only by very strong solar radiation and especially be an increase in ground temperature in the spring. During the cold season, in the months of November through February, almost no adverse effects are to be expected. It is therefore sufficient that a highly efficient cooling-mat device  2  forms a hard-snow layer at the start of the cooling period, for about 24 hours, in the region of the cooling-mat device  2 . This cooling device can then be disassembled and connected to another cooling-mat device for another field to be cooled. Measuring sensors  40  are installed advantageously to the cooling-mat devices  2 , which report the status of each cooling-mat device  2  to a central computer  50  through a line  41  (FIG.  1 ). As soon as a particular value, advantageously the ratio of the snow temperature to the snow depth is exceeded in the region of the cooling-mat device, a smaller suitable device of about 9 kw can deliver coolant from the coolant reservoir  5  to the cooling-mat device  2 . In this way, cooling devices can be saved. 
     The individual lines  23 ,  23 ′ of the cooling-mat parts can be fused together advantageously in the case of damage with the aid of a specially prepared brazing piston from a power supply and be made fully functional, regardless of whether it is lying in snow. It has been observed that with PE lines, this kind of fused connection can withstand a pressure of about 35 bars. Since the operating pressure is about 2 bars, this is more than sufficient. 
     Instead of the nap-like projections  30 ,  30 ′ described in FIGS. 4 and S, which also serve as spacers, it is conceivable to use simple structural adhesive strips consisting of the same material as the mat-device parts. These adhesive strips make it possible for the mat-device parts to be rolled in and out with the thin lines  23 ,  23 ′ getting tangled* or knotted. Transportation of the mats is thereby facilitated. [* German “verhedern” should be “verheddern”] 
     When the present cooling-mat device  2  is applied to ground  1  already covered with a snow layer or directly with spacers onto snow-free ground  1 , so that the ground is at a distances of about 10 to 25 cm, a snow layer is formed as a snow buffer by the cooling-mat device  2  between the ground  1  and the cooling mat device, which prevents the ground from being insulated by air, so that vegetation is not affected adversely. The resulting hard-snow layer is comparable to natural ice sheets on runs. 
     In order to indicate to operators of run rollers and similar things the presence of already installed cooling-mat devices  2  that are not visible, it is recommended that especially the edges of the cooling-mat device  2  be provided with thin metal strips  60 , the presence of which is detected and signaled by sensors in the run rollers. In this way, damage by inappropriate traffic on the cooling-device mat  2  can be avoided. 
     To protect the edges of the cooling-mat device  2 , especially in very steep areas (slope greater than 28%), it is recommended that lattice strips  70  known in the trade (e.g. under the trademark Gittex®) be placed about 10 cm above the edges of the cooling-mat device  2 . This lattice structure, which connects the hard-snow layer into a very compact and stable protective layer above the edges of the cooling-mat device  2 , is recognized immediately by personnel of a run roller, especially when it is colored e.g. blue, so that further traffic on and damage to the edges of the cooling mat can be avoided. 
     An especially promising use of the present cooling-mat devices  2  is recommended in regions where the release of avalanches are to be feared. The present cooling-mat devices are placed in such dangerous regions and held, for example with the aid of metal rods driven into the ground between lines  23 ,  23 ′ of the mat-device parts. By temporary cooling of this dangerous region, adherence of the snow mass on it to the ground is achieved, so that the release of especially dangerous ground avalanches can be avoided. 
     There are additional fields of use of the present cooling-mat devices are in the region of the approach tower of ski jumps or as so-called “greens” in winter golf courses. The cooling-mat devices can guarantee constant competitive conditions for all participants by cooling or warming, since the ground temperature can be kept constant by means of them. For example, it can be avoided that the approach trail of a ski-flying jump is strongly frozen in the morning and very soft in the afternoon. For example, bridges over brooks in ski runs can be provided with a snow layer that has been made durable by installation of the present cooling-mat devices. It is also conceivable to create and operate for a long time cross-country courses in areas with relatively little snow by installing the present cooling-mat devices. 
     The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims.