Abstract:
A cat litter box of the pass through type which includes a tray on which the litter is deposited with the tray having openings in the base for the passage of liquid wastes into a sump or other means for the collection of liquid waste separate from the litter, a convenient means for releasing the collected liquid and means for reducing the release of odors from the collected liquids and residues which cling to the litter. The box is used with litter of a granular type that sheds liquids, and mitigates odor from residues and liquids which have been shed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention concerns litter and litter boxes of the type used in the home for the reception of liquid and solid waste matter commonly used with pets such as cats, dogs, or small animals.  
           [0002]    In wide use are receptacles filled with particulate which absorbs liquid waste and suspends solid waste matter. Regular cleaning of such receptacles is an arduous, disagreeable, costly and wasteful task in that the portion of the litter saturated with liquid must be removed frequently and the receptacle cleaned and recharged with fresh, absorbent material.  
           [0003]    Also common and in wide use are absorbent litters with odor treating components, acting both on the chemical and biological or bacterial components of litter box odor, or sprays or powders which can be added to litter.  
           [0004]    U.S. Pat. No. 6,287,550 discloses a litter system with odor reducing agents, anti-bacterial agents and perfumes to control and reduce litter odor.  
           [0005]    U.S. Pat. No. 5,970,915 discloses a litter box preparation using a dry silica gel granular litter with the application of a disinfectant to the litter box to reduce litter odor.  
           [0006]    Pass-through litter systems are also described. These systems use non-absorbent litter which sheds liquids and grids or filters which retain the litter and collect the liquid waste for disposal.  
           [0007]    U.S. Pat. No. 4,444,148 discloses a litter box using particulate coated with wax to inhibit absorbency to permit liquid waste to pass downwardly through a foraminous tray supporting the layer of granular material into a collection tray which may be provided with absorbent sheet material such as newsprint which eventually must be removed when saturated during a cleaning operation.  
           [0008]    U.S. Pat. No. 2,971,493 discloses a litter box comprised of inner and outer boxes with the inner box provided with a layer of non-absorbent material while the lower box serves to collect liquid waste.  
           [0009]    U.S. Pat. No. 5,193,488 discloses a litter system which has the urine go through a nonabsorbent material in a top tray and then through a pervious bottom of said top tray, thence dropping on a suspended porous aeration tablet or pad.  
           [0010]    U.S. Pat. No. 5,184,574 discloses a litter box using solid litter and a secondary collection sump to collect liquid waste. Non absorbent plastic is suggested as the litter material. The present invention is drawn primarily to an improvement over this litter box system.  
           [0011]    U.S. Pat. No. 6,408,790 discloses a litter box generally similar to the litter box disclosed in U.S. Pat. No. 5,184,574, using non-absorbent litter, except that, instead of a valve, placed within the base is a removable reservoir drawer for the liquid waste that is positioned within the base, so as to receive the liquid waste flowing through the drain pan hole, and the reservoir drawer is removed and re-positioned through a drawer opening in the base perimeter wall.  
           [0012]    A problem exists in known litter boxes using absorbent litter in that the litter must absorb all the liquid. Litter quickly becomes saturated. To avoid malodor, saturated particulate must be disposed of They present a difficult task in periodical treating in that a mass of litter must be removed after only a short time and replaced with fresh, absorbent material.  
           [0013]    A problem exists in the use of odor fighting components embedded in or added to litters which are intended to absorb liquid waste in conventional litter systems, in that the odor fighting compounds must still treat all of the liquid waste. This reduces the capacity of litter to absorb wastes, increases the cost, and limits the period of effective control of odors, even with large amounts and high concentrations of odor fighting agents.  
           [0014]    A problem exists in pass though litter systems using non-absorbent litter and secondary collection that still result in a collection of odorous urine in residues that are unavoidably retained in the litter. Litter must be rinsed to eliminate the residues and even rinsing can fail to remove the accumulated effect of odorous residues.  
           [0015]    Unlike ordinary absorbent litter which normally requires separation of used from unused litter, litter made from silica gel is intended to be replaced all at one time. This reduces the effort associated with daily maintenance, but the period of effective use in prior systems that use silica gel type litters is limited by the need for the litter to absorb all the liquid. Life is further reduced when the silica litter in areas of concentrated use becomes saturated. Unabsorbed liquids in these areas form puddles that will generate strong odors.  
         SUMMARY OF THE PRESENT INVENTION  
         [0016]    The present invention provides a solution to the previously described problems by providing a portable cat litter box including a suspended litter tray and pass through means for liquid waste with convenient means for periodically discharging such waste.  
           [0017]    The improvement of the present invention is in further providing litter in said litter box which is designed to shed the major portion of liquid waste, and to additionally mitigate the odors produced by residues which are unavoidably retained in the litter and block the release of vapors from collected liquids. The benefit of such a litter compound is particularly noted when used with a pass through litter system.  
           [0018]    In this application, odor fighting agents and absorbent capacity are required to act only on the small amount of liquid waste which coats or is trapped between the particles. The period of effective odor control and the cost of maintaining the system is extended compared to other systems because most of the liquid is separated from the litter and removed without removing the litter.  
           [0019]    A litter box according to the present invention includes a tray having a perforate bottom on which a quantity of particulate material is supported with the particulate preferably being of fortified, synthetic material such as granular silica gel, non-absorbent material, such as plastic, embedded or coated with odor fighting agents, or other materials which initially shed liquids but ultimately absorb and/or mitigate the odor-producing qualities of liquid residues.  
           [0020]    Such particulate material serves to receive solid waste as well as permit the flow of liquid waste downward through the perforate bottom into a collection site in a base supporting the tray. The particulate reduces vaporization of the collected liquid and serves also as an odor barrier. It is also helpful and effective in encapsulating fecal material so as to make it more accessible to a scoop for removal.  
           [0021]    In the preferred embodiment, the particulate is generally spheroid in configuration. The granules preferably are of a uniform size, having a diameter in the range of 3-5 millimeters or such diameter as can be effectively retained by the openings in the perforate bottom. The uniform size and spheroid shape serves to facilitate the flow of liquids through the particles and to minimize the intersections of particles that could dam or trap liquids.  
           [0022]    The preferred granules are non-absorbent over the short term (i.e. one minute) but absorb residues which adhere to the particles through surface tension or are trapped between particles over the longer term (i.e.: one hour). Odor neutralizing agents or compounds and anti-bacterial agents may be embedded in or coated upon the granules to further reduce malodor. In order to be retained by the grid and to make periodic cleaning easier, granules in the preferred embodiment will also retain their size and shape following prolonged exposure to liquids.  
           [0023]    Though any number of materials may be used, in the preferred embodiment, granular silica gel, byproducts from the recycling of paper or cardboard, wood, or other organic materials, which are formed into particles generally spheroid in configuration are preferred.  
           [0024]    In silica gel litter, reducing the size of the pores controls absorption rates. In other materials, absorption rates are controlled by either withholding the surfactants which are often added to increase the absorption rate or by applying hydrophobic materials which reduce absorption rates, by providing surface finishes that retard absorption, etc.  
           [0025]    The materials are processed using extruders, pin mills, or pelletizers to produce the spherical shape, compression, and surface finishes which minimize short-term absorption and retain particulate integrity. Meshes or screens are used to produce the uniform size.  
           [0026]    Granules may also be made of naturally odor fighting materials which shed liquids but absorb malodors and are dissolved into the liquid waste itself An example of such a material is potassium aluminum sulfate in crystallized form. Preferred crystals will dissolve slowly and resist binding to one another even after exposure to liquids.  
           [0027]    Granules may also be made from solid, non-absorbent material such as plastic that has been coated with an odor treating material.  
           [0028]    Preferred materials of the invention are sufficiently absorbent to accept odor-neutralizing agents and dispense them into urine from domestic animals. The addition of disinfectant and/or odor reducing agents creates a fortified litter. Useful disinfectants such as commonly found and available under the trade designation LYSOL® may be used. Odor reducing agents of any number of types may be used, including sodium bicarbonate solution or other bicarbonate solutions. A number of other odor-neutralizing and disinfecting agents may be used, including those disclosed in U.S. Pat. No. 4,898,727 to Osada et al., U.S. Pat. No. 6,495,097 to Streit et al., and U.S. Pat. No. 6,253,710 to Ward et al. Other compounds used to fortify the litter may include fungicides and other water-soluble organic agents such as undecylenic acid as disclosed in U.S. Pat. No. 4,517,919 to Benjamin et al. Perfumes may also be added to the litter. The dry material may be brought up to a high liquid weight, the liquid comprising a solution of disinfectant and/or odor reducing agent, and still retain a strong, solid form.  
           [0029]    In the preferred embodiment of the invention the litter is comprised of dry material as described above. The litter is placed in a litter box tray suspended above a collection site.  
           [0030]    In use, the litter sheds most of the liquid waste but may exchange some of the urine or moisture with some of the embedded disinfectant and/or odor reducing agent as the urine flows past the litter, through osmosis. Residues trapped between particles are especially strongly treated with the odor fighting agents. The result is that odors produced by urine and liquid fecal material exposed to the litter are reduced or eliminated for long periods of time.  
           [0031]    As liquids such as urine wash through the fortified litter, small amounts of odor neutralizer and/or antibacterial agent are carried with the urine or other liquid. The further benefit of the invention is that any liquid collected in the sump or receiver of the system is treated with an amount of odor neutralizer and/or antibacterial agent reducing the odors associated with the litter box and the eventual discharge or clean up of the reservoir.  
           [0032]    Alternatively, the litter may consist entirely of odor mitigating materials such as silica gel or potassium aluminum sulfate. Silica gel suitable for use in this system will absorb liquids slowly in order to maximize the flow of liquid into the collection means but trap liquid residuals and odorous vapors in pores. Urine flows through potassium aluminum sulfate crystals. The crystals dissolve so slowly in the liquid that they are useful for long periods of time. Liquid residues and malodors are absorbed into the crystalline structure and the liquid forms a solution after passing through the crystals that has less odor than liquid waste which has not been exposed to the crystals.  
           [0033]    Important objectives of the invention include the provision of a readily cleaned cat litter box that separates liquid from litter and provides a convenient means for eliminating the separated liquid, and a litter adapted to use in the litter box by shedding liquids and mitigating the odors from residues and the collected liquids. By separating wastes from litter and controlling the odor from residues, odor control is improved, liquids are easier to eliminate, and litter will last longer thus reducing cost and waste.  
           [0034]    The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]    [0035]FIG. 1 is a front elevational view of the present litter box.  
         [0036]    [0036]FIG. 2 is a vertical sectional view taken along line  2 - 2  of FIG. 1.  
         [0037]    [0037]FIG. 3 is an enlarged fragmentary view of the portion of FIG. 2 encircled at  3 .  
         [0038]    [0038]FIG. 4 is a front elevational view of the cat litter box temporarily in place on a toilet bowl for cleaning purposes.  
         [0039]    [0039]FIG. 5 is a fragmentary elevation view of a modified cat litter box wherein a litter-receiving tray is of reduced height.  
         [0040]    [0040]FIG. 6 is an enlarged elevational view of a silica gel pellet for the present litter box.  
         [0041]    [0041]FIG. 7 is a perspective view of an alternative embodiment of the base portion of the present invention with handle for controlling the valve and illustrating an alternative handhold.  
         [0042]    [0042]FIG. 8 is a partially schematic view taken along line  8 - 8  of FIG. 7.  
         [0043]    [0043]FIG. 9 is a partially schematic view taken along line  9 - 9  of FIG. 7.  
         [0044]    [0044]FIG. 10 is a sectional exploded view taken along line  9 - 9  of FIG. 7, showing the structure of an alternative type of valve suitable for use in an embodiment of the invention.  
         [0045]    [0045]FIG. 11 is a view of a portion of a preferred embodiment of the perforate bottom of the tray forming a part of the invention, taken in the direction indicated by line  11 - 11 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0046]    With continuing attention to the drawings wherein applied reference numerals indicate parts similarly hereinafter identified, the reference numeral  1  indicates generally a base of the present litter box.  
         [0047]    The base includes a wall  2  about its perimeter which includes front and rear walls and  4  along with end walls  5  and  6 . The walls comprising wall  2  each merge downwardly with a respective one of inwardly inclined bottom walls  7 ,  8 ,  9  and  10  which provide a convenient surface for grasping and carrying of the litter box.  
         [0048]    A support wall or skirt  11  is integral with the above-mentioned inclined bottom walls and provides a stable support for base  1 . Support wall  11  terminates downwardly in a continuous lower edge  11 A.  
         [0049]    A tray  12  of the present litter box is a walled structure with an outer wall  13 . The tray  12  is supported in the base  1 , within base wall  2 , and serves to receive a layer of fortified particulate  16  on a perforate bottom wall  14 . The tray terminates upwardly in a rim  15  having an inwardly turned continuous lip to prevent scattering of the particulate by the pet. Tray  12  is of a size as to seat within base wall  2  on the inclined walls of the base. If so desired the wall  2  of the base may be internally shouldered to support the tray in a spaced manner above the inclined bottom walls of the base. The tray bottom  14  is of perforate construction having a multitude of openings  14 A of lesser size than the smallest dimension of the fortified particulate material for particulate retention.  
         [0050]    A preferred litter particulate is a liquid-shedding pellet having a smooth exterior, fortified with odor controlling agents or other means to mitigate odors from residuals. Such particulates are preferably round or elliptical shape to avoid trapping liquids in the litter, as shown in FIG. 6, having a preferred size of 3-5 mm.  
         [0051]    The preferred fortified litter is a robust pellet that may have odor controlling agents embedded in or coated upon the granules. The fortifying agent is preferably a mixture of odor neutralizing and antibacterial compounds. The fortifying agent may further include fungicides and perfumes.  
         [0052]    The convergent walls  7 ,  8 ,  9 , and  10  of the base terminate downwardly to support a valve body  17  defining a discharge passageway  18 . Valve body  17  also defines a valve seat  20  which carries a rotatable member  21 , shown as being of the plug type, having an opening  22  for communication with passageway  18 . A seal at  23  may be an O-ring retained within a groove  24  extending about valve member  21 . Other valve types may be utilized such as, for example, a ball valve or a slide valve.  
         [0053]    A valve control rod  25  engages member  21  to impart rotational movement thereto. For this purpose control rod  25  is provided with an end  25 A for inserted locked engagement with corresponding socket  26  in member  21 . Control rod end  25 A may have a flat surface for driving engagement with plug member  21 . Rod  25  terminates outwardly to locate a handle  27  in a highly accessible manner outwardly adjacent support wall  11  and front wall  3 . To facilitate assembly and retention of the valve means above described, control rod  25  may be apertured to receive a cotter pin  28  to prevent undesired axial movement of the rod. Handle  27  is preferably proximate to a floor surface F and includes an appendage  27 A such as a wing or arm which, upon arcuate movement, as in the case of rotation of the handle  27 , would come into contact with the floor surface F to prevent opening of the valve  17  and inadvertent waste discharge from the base. To prevent contact with the floor, a valve bottom wall  17 A is offset upwardly from a plane containing wall edge  11 A.  
         [0054]    A modified litter box is disclosed in FIG. 5 wherein a tray at  30  is generally flat while a base wall  2 ′ is of adequate height to confine the litter against discharge. Prime reference numerals in FIG. 5 indicate parts corresponding to parts earlier identified with like base reference numerals.  
         [0055]    In FIG. 4 the litter box  1  is shown in place for cleaning purposes as for example on a toilet bowl B to permit the base to be emptied of liquid waste via valve  17 . It will be noted that the control handle  27  is easily accessible and can be rotated without interference when the base is so located.  
         [0056]    [0056]FIGS. 7 through 10 illustrate portions of another alternative embodiment of a base portion of a cat litter box arrangement according to the present invention. As best seen in FIG. 7, a base  31 , which may be of molded plastic material, contains integral bottom walls  32 ,  34 ,  36  and  38  that slope downwardly toward one another defining a sump  39  in which an opening  50  is located. Base  31  further includes end walls  41  and  42 , front wall  40  and rear wall  43 . Walls  40 ,  41 ,  42 , and  43  are interconnected with one another, extending upwardly and being interconnected with a generally horizontal continuous rim  44 . The tray  12  (shown in FIGS. 1, 2, and  4 ) rests on the base  31  in the same way in which it rests on the base  1 , with the inner walls  45 ,  46 ,  47 , and  48  surrounding a lower portion of the tray  12  when it is in place. Walls  40 ,  41 ,  42 , and  43  thus serve as support walls comparable to the support wall  11  shown in FIGS. 1, 2, and  4 . Inner walls  45 ,  46 ,  47 , and  48  are joined continuously with rim  44 , extending downward therefrom nearly vertically, and at their bottom margins are joined with bottom walls  32 ,  34 ,  36 , and  38  respectively. The bottom walls  32 ,  34 ,  36 , and  38 , defining the sump  39 , slope much more gently toward the middle of the space defined by the walls  40 ,  41 ,  42 , and  43 .  
         [0057]    It will be noted in FIGS. 7 and 8 that end walls  42  and  41  define handholds  54  to facilitate conveniently grasping, lifting, and carrying the base  31  with the tray  12  located thereon.  
         [0058]    Opening  50 , at the lowest point of the sump  39 , is closed by a valve  52 . When the perforate tray containing fortified particulate litter  16  is supported in place on the base  31  liquid waste deposited on the fortified particulate litter  16  disposed in the perforate tray is free to run off the surfaces of the particulate  16  and drain through the perforate bottom  14  of the tray  12  into the sump  39 .  
         [0059]    Release of liquid from the sump  39  is controlled by valve  52  which may be preferably manufactured separately from the base and adhesively attached thereto. The top surface  53  of valve  52  is preferably a flat surface suitable for attachment to a correspondingly flat bottom surface surrounding the opening  50  in the sump  39  of base  31 . Valve  52  is attached to base  31  such that the upper opening  58  of valve  52  is properly aligned with the opening  50  of sump  39  in base  31 .  
         [0060]    As best seen in FIG. 10, the valve  52  includes a valve body  56  defining an upper opening  58  and a drain  60 . A valve piston has a front face  63 . An O-ring  61 , shown partially cut-away, is located in a groove  62  in the valve piston, and will prevent the passage of any liquid through the drain  60  when the valve is closed as shown in FIG. 10. When the valve is in the open position, the face  63  of the piston is in the position shown in broken line, and the O-ring is moved laterally in the valve body  56  so that communication between upper opening  58  and the drain opening  60  is unobstructed and any liquid contained in the sump  39  is released through opening  50 , through upper opening  58  and thence downward out the drain opening  60 . When the valve is closed the O-ring  61  forms a tight seal between upper opening  58  and drain opening  60  preventing any seepage of liquid through drain opening  60 . When the valve  52  is open the O-ring  61  prevents seepage of liquid waste along the control rod or shaft  64  toward the control handle  66 .  
         [0061]    A handle  66  is provided for the operation of the valve and a retainer pin  68  prevents the groove  62  containing an O-ring from being inadvertently removed from the valve body  56 . In a preferred embodiment the handle  66  is accessible to the operator at opening  70  in the front wall  40  of the base  31 , allowing convenient “push-pull” operation of the valve  52 . This arrangement also provides adequate vertical support for the control rod  64 . When the base  31  is located on a toilet bowl the handle  66  is readily accessible for easy emptying and flush cleaning of the litter box.  
         [0062]    As shown in FIG. 11, the tray bottom  14  of the perforate tray  12  of the present invention may be molded to define regularly spaced openings  14 A of a size small enough to prevent the passage of the semi-absorbent litter particulate pellets  16  through the openings. Thus, the bottom  14  preferably includes a grid defining openings  14 A each having a length  76  of about 0.4 inch and a width  78  of about 0.1 inch. Openings  14 A of this size will retain all particles of the litter material  16  having a diameter greater than the width  78  of the grid opening such as particle  16  shown enlarged in FIG. 6.  
         [0063]    It will also be noted that bars  80 ,  82  defining grid openings have knife edges  84  which minimize horizontal areas upon which liquid can collect, thus insuring that liquid deposited on the fortified particulate litter  16  will drain promptly into the sump  39  below.  
         [0064]    The terms and expressions which have been employed in the foregoing  110  specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.