Abstract:
A high-velocity plume of snow produced by mixing streams of a compressed medium, e.g., chilled compressed air and/or liquid nitrogen, and cold water is used as a washing stream, e.g., as a replacement for mechanical scrubbing elements in a car wash. A microprocessor monitors the relevant conditions in the car wash tunnel, e.g., the temperature, barometric pressure, and humidity, and controls the temperature and pressure of streams of water and compressed medium to ensure efficient production of snow; nucleating particles, detergent, and/or wax can also be supplied if necessary. In one preferred embodiment, a plurality of snow guns are mounted on posts extending up either side of and across the top of the wash tunnel, so as to reliably blast each square inch of the vehicle&#39;s surface. The posts may serve as manifolds for water, air, or both, and may be reciprocated along their axes and also rotated back and forth, to ensure full coverage. Preferably the water is recovered and used to chill the compressed air, which may also be fully or partially recovered. A cleansing snow blast produced according to the invention can be provided by a portable device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from Provisional Application Ser. 60/607,482, filed Sep. 7, 2004. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to using snow, that is, a high-velocity plume of water crystallized as snow, manufactured on site by mixing a stream of water with pressurized, chilled air and or/nitrogen or another gas as a scrubbing element in vehicle wash systems, in lieu of brushes, dangling strips of plastic foam, and the like. The same technique can be used in other washing applications.  
       BACKGROUND OF THE INVENTION  
       [0003]     In the typical vehicle wash system (hereinafter sometimes “car wash”) the vehicle is drawn through a wash tunnel having a sequence of stations at which various steps in the process are performed. Typically, at a first station warm soapy water is sprayed onto the vehicle; then fibrous brushes of various types, dangling strips of plastic, or other physical objects are rubbed against the vehicle to scrub and loosen the soil; then the vehicle is rinsed again, and is finally dried by high pressure air. Other steps, such as application of spray wax, and specialized undercarriage and wheel cleaning treatments, are of course also commonly employed.  
         [0004]     The present invention is based on the observation by the inventor that the side of his car that was exposed to a blizzard one evening was completely cleaned by the blown snow, even though the remainder of the car was filthy due to melted snow, salt and the like. The same observation was made on another night as to the opposite side of the car. These observations led the inventor to think that the scrubbing step of conventional carwashes might usefully be replaced by a snow-spraying step, and that this might have substantial advantages.  
         [0005]     Specifically, a problem with rotating brushes and foam strips and the like used as scrubbing devices is that they cannot well accomodate vehicles of varying size and those with protruding accessories and the like. For example, roof racks, rear-view mirrors and radio antennas are often damaged by such scrubbing devices. Furthermore, many larger vehicles such as SUVs, RVs, and of course trucks cannot be accomodated in standard carwashes. Moreover, even if a wash system were sized suitably to accomodate such larger vehicles, the problem of damage to protruding accessories would remain. Still further, use of such mechanical scrubbing devices is thought by many persons inevitably to involve some scratching of the car&#39;s paint, and many refuse to use such car washes for that reason.  
         [0006]     Employment of a snow blast as the scrubbing element, that is, in lieu of brushes or plastic strips or the like, would avoid many of these problems. The snow blast would not need to touch the car, so there would be no problem with protruding objects. Similarly, the wash tunnel could easily be sized to suit the vast majority of vehicles, since mechanical contact would be avoided. For the same reason, the problem of scratched paint could be eliminated. Possibly a savings in construction or operation cost could also be realized (although as of the filing of this application this possibility has not been fully investigated).  
         [0007]     The art has suggested that “matter which is capable of being changable in its state or phase such as water, is used in a solid phase”, specifically as shaved ice, for cleaning cars. See Courts patent 2,699,403. However, as will appear below, the present invention involves numerous advantages over the basic concept shown by Courts. Various patents, including Miyahara 4,977,910, Palombo 5,637,027, Bowen et al 5,853,128 and Borden 6,066,032, show using liquid or frozen carbon dioxide for various cleaning purposes. Dye patent 2,536,843 shows adding soft pellets to the water stream in a car wash.  
         [0008]     The art also shows equipment and techniques for the artifical manufacture of snow, which, broadly speaking, could be used in implementation of the present invention. See, e.g., www.snowmakers.com, or www.arecosnow.com. However, the inventor is unaware of any reference specifically suggesting the combination of known snowmaking equipment and known car washing techniques, including the Courts patent.  
       SUMMARY OF THE INVENTION  
       [0009]     According to the present invention, blasts of snow produced by mixing streams of cold compressed air or another compressed medium, for example, liquid nitrogen, and cold water are used as a cleansing spray. A plurality of such sprays could be arranged as the scrubbing element in a car wash, or a single spray can be provided on a wand, as in a conventional pressure washing system. More specifically, a high-velocity plume of water crystallized as snow, perhaps with some unfrozen water mixed therewith, to carry away the dislodged soil, and possibly also with a liquid or micro-granular detergent is sprayed against a vehicle or any other object to be washed.  
         [0010]     In the car wash embodiment, a microprocessor monitors the relevant conditions in the car wash tunnel, e.g. the temperature, barometric pressure, and humidity, and controls the temperature and pressure of streams of water and air to ensure efficient production of snow of suitable characteristics for cleaning without abrasion. Nucleating particles can also be supplied if necessary. In one preferred embodiment, a plurality of snow guns are mounted on posts extending up either side of and across the top of the wash tunnel, so as to reliably blast each square inch of the vehicle&#39;s surface. The posts may serve as manifolds for water, air, or both, and may be reciprocated along their axes and also rotated back and forth, to ensure full coverage. If chilled compressed air is used, preferably the water is recovered and used to chill the compressed air, which may also be fully or partially recovered.  
         [0011]     As noted, the principles of the invention could also be used to provide a portable device, comparable to existing pressure washing equipment, that would provide a blast of snow instead of high-pressure water, as a cleaning stream. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention will be better understood if reference is made to the accompanying drawings, in which:  
         [0013]      FIG. 1  shows a schematic perspective view of a car wash tunnel according to the invention, with a schematic diagram of the principal components of the snow blast system;  
         [0014]      FIG. 2  shows a partially cut-away perspective, and  FIG. 3 a  cross-sectional view of one of the snow guns according to the invention;  
         [0015]      FIG. 4  shows one embodiment of a mechanism for oscillating and reciprocating the air and water supply manifold assembly;  
         [0016]      FIG. 5  shows a detail of the  FIG. 4  mechanism;  
         [0017]      FIG. 6  shows schematically a portable device incorporating the teachings of the invention; and  
         [0018]      FIG. 7  shows an alternative construction for a snow nozzle.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     As mentioned,  FIG. 1  shows a schematic perspective view of a car wash tunnel  10  according to the invention, shown with the near wall and roof removed, and with a schematic diagram of the principal components of the snow blast system. Vehicles (not shown) pass through the wash tunnel from left to right in the diagram. The car wash system includes an initial rinse station  12 , at which the vehicle is blasted with warm soapy water, to loosen and remove as much surface soil as possible; a scrubbing station  14 , at which the conventional brushes, foam strips or the like are replaced by blasts of snow according to the invention, and remove substantially all soil; a second post rinse station  16 , where the vehicle is again sprayed with water; and a drying station, indicated at  18 , where the vehicle is dried by blasts of air.  
         [0020]     As indicated, the initial rinse station  12 , the final rinse station  16 , and the drying station  18  are generally conventional, but their implementation may be optimized in a car wash system incorporating the snow blast scrubbing technique of the invention. For example, in order to save on the energy costs of producing snow, particularly in warmer weather, it is desirable to reclaim as much of the cold air used as possible, so that the scrubbing station  14  is separated from the rinse stations  12  and  16  by baffles  20  and  22  respectively. It is also desirable to process the rinse water streams separately from the water stream resulting as the snow melts, so that the floor of the wash tunnel is sloped separately at each station, as indicated at  24 , and separate drains are provided at each station. Thus, the soap and prerinse water stream is collected at a drain  26  and processed for reuse, at  28 , and the post rinse water is similarly collected at a drain  30  and processed for reuse at  32 .  
         [0021]     Turning now to the specific improvements provided according to the invention, as noted at the scrubbing station  14  the vehicle is blasted by sprays of snow from a number of snow guns  40  rather than being mechanically scrubbed by brushes, foam strips or like devices. As illustrated, preferably the snow guns are arranged at least along vertical supports  42  extending up either side of the wash tunnel, and along a horizontal support  44  extending across the wash tunnel  10 ; similar snow guns could also be arranged to spray the undercarriage of the vehicle. It is considered to be within the invention and the skill of the art to provide adjustable spacing of the supports  42  and  44  responsive to the size of the vehicle, so that the snow guns could be spaced an optimum distance from the surfaces of vehicles of substantially varying overall dimensions, so that the snow spray impacting the vehicle would be of optimum condition and density. For example, it would be comparatively straightforward to provide the attendant with an adjustable mechanical device to be brought to within a given distance from one flank and the roof of each vehicle as it enters the tunnel  10 , and to then press an “Enter” button or the like, so as to record the dimensions. When the vehicle subsequently reaches the scrubbing station  14 , the supports  42  and  44  could be moved accordingly, under control of a microprocessor (“μP”)  46 .  
         [0022]     As indicated throughout  FIG. 1  by the symbol “μP”, microprocessor  46  controls many aspects of the operation of the snow gun scrubbing station  14  according to the invention. These are discussed further below. Briefly, the microprocessor  46  monitors the temperature, barometric pressure, and humidity within the wash tunnel in the vicinity of the scrubbing station  14 , and adjusts the temperature and pressure of the incoming water and air streams so as to ensure that snow of the correct consistency is provided as the scrubbing spray.  
         [0023]     It should be understood that reference to “compressed air” herein is to be read (where the context does not clearly exclude doing so) to include reference to additional compressed media that would also suffice to produce a spray of snow if mixed with a stream of water under the appropriate conditions. The use of liquid nitrogen for this purpose is discussed further below. The compressed media used to form snow when mixed with a stream of water could also include compressed or liquid air, as well as liquid or compressed nitrogen, and combinations of these and other suitable media. Further, reference to a pressurized, high-velocity stream or plume of snow should be understood to possibly include unfrozen water (possibly useful to carry off the loosened soil), detergents, wax, and the like.  
         [0024]     As will be apparent to those of skill in the art, manufacture of snow demands production of sprays of water and chilled air (or another compressed medium, as above); if a spray of water is mixed with one of air under the correct conditions, a stream of snow is produced. Snowmaking as practiced in ski resorts is normally only undertaken when the weather is suitable, i.e., the air temperature is below 32° F., so that only the water needs to be cooled to the freezing point. However, in order that a car wash employing snow as the scrubbing agent can operate year-round, it will be necessary to chill both water and air. In order to reduce the cost of operation as much as possible, it is important to provide the streams of cold water and air as efficiently as possible.  FIG. 1  shows several expedients that may prove useful in this effort.  
         [0025]     For example, to the extent it is possible to keep reusing previously chilled air, the energy cost involved in cooling warmer ambient air can be eliminated or reduced. (It is not anticipated that it will be practical to thus reclaim liquid nitrogen if used as the medium.) Accordingly, cool air returns  48  are provided in the floor of the scrubbing section  14  of the wash tunnel  10 , and baffles  20  and  22  are provided to separate this area from the remainder of the tunnel and the outside air. That is, although it will probably be impractical to completely segregate the atmosphere of the scrubbing section  14 , baffles  20  and  22  can be expected to limit the influx of warmer ambient air to some extent. Streams of air, as practiced in markets to keep fresh food chilled while permitting free access thereto, might also be employed to separate the several areas of the wash tunnel.  
         [0026]     Air collected by returns  48  is dried and filtered as necessary by conventional equipment, not shown, and then compressed in air compressor  50 . Compressing the air warms it, of course, so it must be cooled again before reuse in snow guns  40 . In one possible embodiment, cooling of the air can be at least partially accomplished by heat exchange with the water also recovered from the scrubbing section  14 . That is, snow ejected from snow guns  40  will melt as it hits the vehicle, and the water resulting is collected in a floor drain  52 . It is then filtered at  52 , cooled by mechanical refrigeration unit  54 , and supplied to chilled-water tank  56  for storage. Air from compressor  50  is ducted through serpentine ducts  58  disposed in tank  56 , whereby the air is chilled. The chilled air is then supplied again to snow guns  40 , as indicated by arrow  60 ; similarly, pump  62  forces water from tank  56  to the snow guns  40 .  
         [0027]     As is well known, the formation of snowflakes can be hastened by the introduction of a particulate material into either of the water or air streams; the particulate can be dust, smoke, pollen, or the like. In this context it must obviously not be an abrasive material. To this end a nucleator is shown being introduced into the water stream at  64 .  
         [0028]     As mentioned above, a microprocessor  46  (using this term to refer generically to programmable controller devices of all types, including personal computer-based systems) controls the parameters according to which the streams of air and water (and nucleator, if used) are introduced into the scrubbing station  14  to ensure efficient production of snow. To this end, the temperature, barometric pressure, and humidity in the scrubbing station  14  are monitored, as indicated at  66 . Similarly, the temperature of the water and air streams can be monitored at one or more locations, as indicated at  68 . Variables controlled in accordance with this information and stored data defining the optimal snowmaking conditions include the pressure and temperature of the compressed nitrogen or other media, if used; the air pressure, controlled by operation of compressor  50 ; the water temperature, controlled by operation of mechanical refrigeration unit  54 ; the water pressure, controlled by operation of pump  62 ; and the air temperature, controlled by residence time in the heat exchange coils  58 , and thus being a function of the water temperature and air pressure as well. Due to this complex relationship additional cooling of the air stream, indicated at  70 , may be desirable. Of course, the flow rates of the water and nitrogen and/or air streams could be monitored and controlled in addition to, or in lieu of, the pressures thereof.  
         [0029]     Some degree of experimentation can be expected to be required in order to determine the optimal characteristics of the snow required to scrub soil from vehicles, and then to arrive at the most efficient parameters for the air and water streams used to produce the snow; such experimentation is clearly within the skill of the art. It will be appreciated that as cooling of the air and water streams will occur as they are sprayed into the scrubbing chamber, due to their expansion from a pressurized condition to atmospheric pressure, they will presumably both need to be cooled to slightly above 32° F. Similarly, a wide variety of possible designs for the snow guns and related apparatus will occur to those of skill in the art. One possible embodiment of these will now be discussed with respect to  FIGS. 2-5 . Again, experimentation concerning and optimization of these constituents of a system according to the invention is considered to be within the skill of the art, and various embodiments not shown specifically herein to be within the scope of the invention.  
         [0030]      FIGS. 2 and 3  show respectively cross-sectional and perspective views of a single snow gun assembly  40  designed so as to be readily connected in series, so that a number of such assemblies  40  can conveniently be provided on either side of the scrubbing station  14  and across its top, as illustrated in  FIG. 1 . In this embodiment, a number of snow gun assemblies are connected to “tee” fittings  82  connected by lengths of pipe  84 , so that the construction  85  forms both support structure for the snow guns  40  and a manifold for, in the configuration shown, chilled compressed air. Water, chilled and under pressure, is supplied to the snow guns  40  by way of a similar construction  89  comprising lengths  88  of pipe or tubing connected by tee fittings  86 .  
         [0031]     As illustrated, the air exits the snow gun  40  by way of a nozzle  90 , while the water exits from an annular ring of orifices  92  drilled in a body  94 . The nozzle  90  and annular ring of orifices  92  are surrounded by a tubular member  96  defining a mixing chamber, which may be of assistance in ensuring good mixing of the water and air streams and thus efficient snowmaking. Of course numerous options for ensuring good mixing will occur to those of skill in the art; for example, the water jets exiting the orifices  92  might be directed at angles so as to intersect the air stream. The simple cylindrical shape of the member  96  might be replaced by a converging cone, so that the air and water streams would have to pass through a single orifice some distance from the exit of nozzle  90 . The positions of the air and water streams could be exchanged, i.e., so that the water stream is emitted from the central nozzle of the gun, and the air from the surrounding orifices. Additional annular rings of water and air nozzles might be useful. Other subjects for experimentation and optimization are within the skill of the art and the scope of the invention. Similarly, the snowmaking industry, although directed primarily to snowmaking for ski slopes, may have information useful in the car wash context, and the teachings of that art are incorporated herein by reference.  
         [0032]     The snow gun  40  is shown as being assembled by threading the body  94  over the nozzle  90 , which in turn is threaded to the tee fitting  82 . The orifices  92  communicate with an internal manifold  98 , to provide adequate flow, which could be machined into the body and then sealed off by backing plate  100 . Water is supplied via a fitting  102  threaded into body  94  and communicating with manifold  98 . Again, numerous variations and improvements on this structure will occur to those of skill in the art, and may prove useful after experimentation. For example, it might be quite satisfactory to form the orifices for water jets by assembling a number of small fine-spray nozzles to a tube formed into a ring and surrounding a relatively large air duct, all disposed within a mixing tunnel. As noted above, possibly it would be useful to have the water streams in the center of the snow gun, and be surrounded by air streams; or several annular streams of both might be best. Such variations and modifications are considered within the scope of the invention.  
         [0033]      FIG. 4 , a detail of which forms  FIG. 5 , shows a simple mechanism for reciprocating the assembly of snow guns with support structure also providing air and water manifolds, while also rotating the assembly back and forth through an arc, so as to ensure that the snow stream impacts the entire surface of the vehicle being washed. In this embodiment, the assemblies of snow guns  40  and their supporting tubular manifolds  85  and  89  are supported at a base  104 , at which the manifolds are connected to supplies of chilled water and chilled compressed air by flexible tubing. Base  104  is supported so that it can be lifted and rotated, as indicated generally at  106 . More specifically, a cylindrical rod member  108  fixed to base  104  slides within a tubular bearing member  110 ; typically a similar structure would be provided at the upper end of a vertical assembly of this kind, and at both ends of a horizontally-mounted assembly. A rigid arm  112  is fixed to rod member  108 , and passes through a spherical ball bushing member  114  (see  FIG. 5 ) confined within a correspondingly-shaped race  116  in turn fixed to a crank throw  118  rotated by a motor  120 . Accordingly, the angle between arm  112  and crank throw  118  is allowed to vary, due to the provision of spherical bushing  114  therebetween. Further, the fit between the bore in spherical bushing  114  and arm  112  is such that arm  112  can slide freely back and forth through the bore and rotate therein. Thus, as crank throw  118  is rotated by motor  120 , arm  112  is driven so as to raise and lower rod  108  while rotating it back and forth through an arc; this motion is translated to base  104 , thence to manifolds  85  and  80 , and thus to snow guns  40 , ensuring good variation in the direction of spraying and thus good scrubbing of the vehicle to be cleaned.  
         [0034]     It will be apparent that numerous other mechanisms could be provided for accomplishing the same or better results; perhaps the most likely embodiment to occur to those of skill in the art would be to provide hydraulic or pneumatic actuation of a mechanism moving the snow guns to ensure good coverage. Another possibility would be to articulate the snow guns with respect to the support structure, connecting the guns to the water and air manifolds with flexible hoses, so that the mass of the support structure would not need to be moved with the guns.  
         [0035]     As mentioned above, it is within the scope of the invention to employ a stream of a compressed medium other than or in addition to compressed air to cooperate with a stream of water to form snow. Compressed nitrogen is one possible choice for this alternative medium.  
         [0036]     More specifically, nitrogen is widely and relatively inexpensively available, as a gas at 3000 psi in heavy cylinders or as a liquid in Dewar vessels at low temperature and relatively lower pressure. In either case, the nitrogen is supplied under high pressure, so that as it is released into the atmosphere, it will expand and be rapidly cooled; if the water stream is efficiently mixed with the nitrogen as it expands, a stream of snow will be produced, which could be used in accordance with the principles of the invention, as above, as a washing stream. Employment of liquid nitrogen instead of, or in addition to, compressed and cooled air as the medium to be mixed with water to form a blast of snow might well be economically preferable, as it could eliminate or reduce the cost of chilling and compressing equipment. As above, experimentation to determine workable and optimal conditions to form snow of the preferred consistency is considered to be within the skill of the art. As mentioned above, in a vehicle wash system employing liquid nitrogen as the medium it is not expected to be feasible to reclaim the nitrogen for reuse, as might be possible with compressed air.  
         [0037]     It is also within the scope of the invention to employ the principles thereof in a portable device, comparable in size, for example, to existing pressure washing equipment. Such equipment would comprise a high-pressure water pump, adapted to be connected to a water line, possibly with addition of a detergent, a source of compressed chilled air, and/or another medium suitable for forming snow when mixed with water, e.g., liquid nitrogen, as above, and a mixing nozzle. These components, together with the required hoses, valves, power connection for the pump, and the like, could readily be mounted on a wheeled cart for convenience. See  FIG. 6 . As illustrated, a supply of water, indicated at  140 , with detergent optionally added at  142 , is connected to a high-pressure pump  144 , driven by a motor  146 . These components, together with a tank of liquid nitrogen  148 , are mounted on a cart  150  for convenient movement. If desired, a connection made be provided to a stream of chilled compressed air, as above, as indicated at  151 . The nitrogen from tank  148 , compressed air if used, and high-pressure stream of water are supplied to a cleansing gun  152  by flexible hoses  154 . Gun  152  comprises a control trigger  156 , a gripping handle  158 , a wand  160 , and a nozzle assembly  162 .  
         [0038]      FIG. 7  provides a cross-sectional view of one possible embodiment of such a nozzle assembly  162 ; in this design, the nozzle is akin to those used for oxyacetylene torches, with the medium, again perhaps liquid nitrogen and/or compressed air emitted from a number of apertures  164  disposed in an annular arrangement around a central nozzle  166  emitting the stream of water. As the liquid nitrogen and/or air reach atmospheric pressure, it will be rapidly cooled, and, if properly mixed with the water stream, will cause a stream of snow to be formed. A tubular guard  168  may be useful in controlling the mixing conditions to optimize snow formation. Again, some experimentation will be necessary to optimize the formation of an effective stream of snow; this experimentation is believed to be within the skill of the art. One area to be explored would be variation of the axial spacing of the nozzles for the water and medium; in using liquid nitrogen as the medium, that is, where the cooling of the nitrogen which occurs as its pressure is reduced to ambient, is employed to cool the water stream to form snow as the water exits the nozzle, it would be important to avoid ice build-up from condensation on the nozzle surfaces, to prevent clogging.  
         [0039]     As noted above, the high-velocity plume of snow provided as a cleansing agent according to the invention may include water crystallized as snow, unfrozen liquid water, and a detergent. It is also within the scope of the invention to include a liquid or micro-granular wax to the plume of snow produced according to the invention.  
         [0040]     While a preferred and several alternative embodiments have been described, the invention is not to be limited thereto.