Automated self-cleaning litter box for cats

Abstract

An improved automated self-cleaning litter box for cats, of the kind having a housing defining an upwardly open chamber for storage of a supply of cat litter, accessible to a cat and having path members on opposed side walls defining a comb path from one end of the chamber to the other. A comb, normally stored at the comb storage end of the chamber, is driven forward along the path to the discharge end of the chamber and back to its original storage position. As the comb traverses the chamber forwardly it engages any clumps of waste in the litter and carries them to a disposal receptacle at the discharge end of the chamber. The improvement includes a sensor for sensing the presence of a cat in the litter chamber; a photo electric sensor is preferred, but an infra red, weight, or even an audible sensor can be used. A delay device actuates the comb drive a predetermined time interval after the sensor ceases to sense the presence of a cat in the litter chamber. In the improved construction the comb path includes multi-perforate track members on opposite sides of the litter chamber; those tracks are engaged by rotatable drive wheels connected to the comb. The comb drive includes a reversible electric motor, mounted on the same carriage as the comb. A transparent, biodegradable receptacle is used; alarms for a full receptacle and for an insufficient litter supply are provided.

I claim: 
     
       1. In an improved self-cleaning cat litter box including: a pan-shaped housing having a bottom and two spaced side walls connecting a storage end wall to a discharge end wall, the housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb path extending from the storage end wall to the discharge end wall;   a comb extending between the side walls; and   a comb drive for driving the comb along the comb path from a storage position adjacent the storage end wall to a discharge position adjacent the discharge end wall and back to the storage position, the comb projecting down into the litter chamber to a level below the fill level and near the housing bottom while the comb moves toward the discharge end wall so that the comb engages any clumps in the litter and carries such clumps to the discharge position;   the improvement comprising:   a cat exit sensor for sensing exit of a cat from the litter chamber;   delay means, connected to the cat exit sensor and to the comb drive, for actuating the comb drive to drive the comb from the storage position to the discharge position and back to the storage position at a predetermined time subsequent to sensing of exit of a cat from the litter chamber and   a litter level sensor for sensing an insufficient quantity of litter in the litter chamber, below the given fill level.   
     
     
       2. An improved cat litter box according to claim 1, and further comprising: a waste receptacle located outside of the litter chamber adjacent to the discharge end wall; and   deflection means, on the comb path, for deflecting the comb to deposit clumps carried by the comb into the waste receptacle.   
     
     
       3. An improved cat litter box according to claim 2 in which: the waste receptacle includes a base pan and a cover hinged to the base pan; and   the deflection means raises the cover of the waste receptacle to enable deposit of clumps in the base pan, of the waste receptacle.   
     
     
       4. An improved cat litter box according to claim 2 in which the waste receptacle comprises: a base pan for receiving and storing cat waste from the litter box;   a cover hinged to and normally covering the base pan; and   guide means, on the cover, engageable by the deflection means of the litter box to raise the cover to an open position.   
     
     
       5. An improved cat litter box according to claim 1 in which the cat exit sensor comprises: radiation source, mounted adjacent one side of the litter chamber, the radiation source producing a beam that projects across the litter chamber above the fill level; and   a detector mounted adjacent the other side of the litter chamber in position to intercept the beam from the radiation source.   
     
     
       6. An improved cat litter box according to claim 5 in which: the radiation source is a light source and the beam is a light beam;   the detector is a photodetector; and   the light source and the photodetector are mounted on opposite side walls of the litter chamber.   
     
     
       7. An improved cat litter box according to claim 1 in which the litter level sensor comprises: a radiation source, mounted adjacent one side of the litter chamber, the radiation source producing a beam that projects across the liter chamber below the fill level; and   a detector mounted adjacent the other side of the litter chamber in position to intercept the beam from the radiation source.   
     
     
       8. In an improved self-cleaning cat litter box including: a pan-shaped housing having a bottom and two spaced side walls connecting a storage end wall to a discharge end wall, the housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb path extending from the storage end wall to the discharge end wall;   a comb extending between the side walls; and   a comb drive for driving the comb along the comb path from a storage position adjacent the storage end wall to a discharge position adjacent the discharge end wall and back to the storage position, the comb projecting down into the litter chamber to a level below the fill level and near the housing bottom while the comb moves toward the discharge end wall so that the comb engages any clumps in the litter and carries such clumps to the discharge position;   the improved construction comprising:   a track member, defining the comb path, mounted to one side wall above the fill level;   a carriage supporting the comb;   a guide wheel mounted on the carriage and engaging the track member;   and a reversible drive motor, comprising a part of the comb drive, mounted on the carriage.   
     
     
       9. An improved cat litter box according to claim 8, in which the carriage includes a comb shaft extending across the litter chamber from one side wall to the other, and further comprising: a second track member mounted on the other side wall above the fill level; and   a second guide wheel mounted on the carriage and engaging the second track member.   
     
     
       10. An improved cat litter box-according to claim 9 in which: each track member has a multiplicity of equally spaced perforations along the track;   and further comprising:   a first drive wheel mounted on one end of the comb shaft and having a plurality of radial drive pins engageable in the perforations of the first track member; and   a second drive wheel mounted on the other end of the comb shaft and having a plurality of radial drive pins engageable in the perforations of the second track member.   
     
     
       11. An improved cat litter box according to claim 10 in which the drive means comprises a gear train connecting the motor to the comb shaft to rotate the comb shaft. 
     
     
       12. An improved cat litter box according to claim 11 in which each track member includes an upwardly inclined extension at its opposite ends so that the comb is directed upwardly above the fill level at both ends of the litter chamber. 
     
     
       13. An improved cat litter box according to claim 8 and further comprising: a cat exit sensor for sensing exit of a cat from the litter chamber; and   delay means, connected to the sensor and to the reversible motor, for actuating the comb drive motor to drive the comb from the storage position to the discharge position at a predetermined time interval subsequent to sensing of exit of a cat from the litter chamber.   
     
     
       14. An improved cat litter box according to claim 13, and further comprising: a waste receptacle located outside of the litter chamber adjacent to the discharge end wall; and   deflection means, on the comb path, for deflecting the comb to deposit clumps carried by the comb into the waste receptacle.   
     
     
       15. An improved cat litter box according to claim 14 in which: the waste receptacle includes a base pan and a cover hinged to the base pan; and   the deflection means raises the cover of the waste receptacle to enable deposit of clumps in the base pan of the waste receptacle.   
     
     
       16. An improved cat litter box according to claim 13 in which the cat exit sensor comprises: a radiation source, mounted adjacent one side of the litter chamber, the radiation source producing a beam that projects across the litter chamber above the fill level; and   a detector mounted adjacent the other side of the litter chamber in position to intercept the beam from the radiation source.   
     
     
       17. An improved cat litter box according to claim 16 in which: the radiation source is a light source and the beam is a light beam;   the detector is a photodetector; and   the light source and the photodetector are mounted on opposite side walls of the litter chamber.   
     
     
       18. An improved cat litter box according to claim 8 and further comprising: a litter level sensor for sensing an insufficient quantity of litter in the litter chamber, below the given fill level.   
     
     
       19. An improved cat litter box according to claim 18 in which the litter level sensor comprises: a radiation source mounted adjacent one side of the litter chamber, the radiation source producing a beam that projects across the latter chamber below the fill level; and   a detector mounted adjacent the other side of the litter chamber in position to intercept the beam from the radiation source.   
     
     
       20. In an improved self-cleaning cat litter box including: a pan-shaped housing having a bottom and two spaced side walls connecting a storage end wall to a discharge end wall, the housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb path extending from the storage end wall to the discharge end wall;   a comb extending between the side walls;   a comb drive for driving the comb along the comb path from a storage position adjacent the storage end wall to a discharge position adjacent the discharge end wall and back to the storage position, the comb projecting down into the litter chamber to a level below the fill level and near the housing bottom while the comb moves toward the discharge end wall so that the comb engages any waste clumps in the litter and carries such waste clumps to the discharge position; and   a waste receptacle locate outside of the litter chamber adjacent to the discharge end wall, for receiving waste carried to the discharge end of the litter box by the comb;   the improved construction comprising: a waste receptacle sensor for sensing filling of the waste receptacle;   an excess waste alarm actuated by the waste receptacle sensor;     a litter level sensor for sensing an insufficient quantity of litter in the litter chamber, below the given fill level; and   an insufficient litter alarm actuated by the litter level sensor.   
     
     
       21. An improved cat litter box according to claim 20 in which the waste receptacle sensor comprises: a radiation source, mounted on an extension of one side wall beyond the discharge end wall, the radiation source producing a beam that projects across the waste receptacle; and   a detector, mounted on an extension of the other side wall beyond the discharge end wall, positioned to intercept the beam from the radiation source.   
     
     
       22. An improved cat litter box according to claim 20 in which the litter level sensor comprises: a radiation source, mounted adjacent one side of the litter chamber, the radiation source producing a beam that projects across the litter chamber below the fill level; and   a detector mounted adjacent the other side of the litter chamber in position to intercept the beam from the radiation source. .Iadd.   
     
     
       23.  A self-cleaning cat litter box comprising: a pan-shaped housing having two opposed sidewalls, the housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb extending between the two opposed sidewalls;   comb drive means for driving the comb between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level while the comb moves toward the discharge position so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   litter supply sensor means for sensing an insufficient supply of litter in the litter chamber..Iaddend..Iadd.24. A self-cleaning cat litter box comprising:   a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   moving means disposed in the pan-shaped housing;   a carriage supporting the moving means; and   drive means for driving the moving means between a storage position and a discharge position, the moving means projecting down into the litter chamber to a level below the fill level while the moving means moves toward the discharge position so that the moving means engages clumps in the litter and moves such clumps toward the discharge position;   said drive means including motor means mounted on the carriage for driving the moving means between the storage position and the discharge   
     
     
        position..Iaddend..Iadd.25.  The litter box of claim 24 wherein the motor 
     
     
        means includes a reversible drive motor..Iaddend..Iadd.26.  A self-cleaning cat litter box comprising: a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a waste receptacle located outside the litter chamber;   a comb disposed in the litter chamber;   comb drive means for driving the comb between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level while the comb moves toward the discharge position so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   waste level sensor means for sensing when waste has reached a predetermined level in the receptacle, and wherein said waste level sensor means is arranged to perform a sensing operation internally of said receptacle..Iaddend..Iadd.27. A self-cleaning cat litter box comprising:   a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb disposed in the litter chamber;   comb drive means for driving the comb between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level while the comb moves toward the discharge position so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   mode selector means for selecting between at least a manual operation mode for said comb drive means and an automatic operation mode for said comb drive means..Iaddend..Iadd.28. A self-cleaning cat litter box comprising:   a pan-shaped housing having two opposed sidewalls, the housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb drive coupled to the housing;   a comb extending between the two opposed sidewalls and being coupled to the comb drive and movable between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level so that the comb engages clumps in the litter and carries such clumps to the discharge position; and   a litter supply sensor coupled to the housing..Iaddend..Iadd.29. The litter box of claim 28 wherein the litter supply sensor is disposed to sense an insufficient supply of litter in the litter chamber..Iaddend..Iadd.30. The litter box of claim 29 wherein the litter supply sensor includes a radiation source mounted in the litter chamber and disposed to produce a beam that projects across the litter chamber and a detector mounted in the litter chamber to intercept the beam from the radiation   
     
     
        source..Iaddend..Iadd.31.  A self-cleaning cat litter box comprising: a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb drive coupled to the housing;   a comb extending between two opposed sidewalls and being coupled to the comb drive and movable between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   a comb supporting carriage, said comb drive including a drive motor mounted on the carriage..Iaddend..Iadd.32. The litter box of claim 31 wherein the   
     
     
        drive motor is reversible..Iaddend..Iadd.33.  A self-cleaning cat litter box comprising: a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb drive coupled to the housing;   a comb extending between two opposed sidewalls and being coupled to the comb drive and movable between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   a mode selector switch operatively connected to said comb drive, the switch being moveable between a manual operation position wherein an operator causes the comb to move toward the discharge position and an automatic operation position wherein the comb moves toward the discharge position automatically upon the occurrence of a predetermined event..Iaddend..Iadd.34. A self-cleaning cat litter box comprising:   a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a waste receptacle located outside the litter chamber;   a comb disposed in the litter chamber;   comb drive means for driving the comb between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level while the comb moves toward the discharge position so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   a waste level sensor coupled to the litter chamber, wherein said waste level sensor is arranged to perform a sensing operation internally of said receptacle..Iaddend..Iadd.35. The litter box of claim 34 further including an alarm coupled to the waste level sensor, the alarm being activated when the waste level sensor determines that waste in the waste receptacle has reached a predetermined height..Iaddend..Iadd.36. A self-cleaning cat litter box comprising:   a pan-shaped housing having two opposed sidewalls, the housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb extending between the two opposed sidewalls; and   comb drive means for driving the comb between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level while the comb moves toward the discharge position so that the comb engages clumps in the litter and moves such clumps toward the discharge position, the comb being positioned above the fill level in the storage position and the discharge   
     
     
        position..Iaddend..Iadd.37.  A self-cleaning cat litter box comprising: a housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb drive coupled to the housing;   a comb extending between the two opposed sidewalls and being coupled to the comb drive and movable between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level so that the comb engages clumps in the litter and moves such clumps toward the discharge position and being positioned above   
     
     
        the fill level in the storage position..Iaddend..Iadd.38.  A self-cleaning cat litter box comprising: a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a waste receptacle located outside the litter chamber;   a comb disposed in the litter chamber;   comb drive means for driving the comb between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level while the comb moves toward the discharge position so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   waste level sensor means for sensing when waste has reached a predetermined level in the receptacle; and   wherein said waste level sensor means includes a source of radiation..Iaddend..Iadd.39. The litter box of claim 38 wherein said waste level sensor means further includes a detector for generating a signal in   
     
     
        response to radiation from said source..Iaddend..Iadd.40.  The litter box of claim 39 wherein said waste receptacle includes first and second walls, said radiation source being located on said first wall, said detector being located on said second wall, such that waste at said predetermined level blocks radiation transmission between said radiation source and said detector..Iaddend..Iadd.41. The litter box of claim 27 further comprising a sensor system for determining whether a cat is in the litter chamber..Iaddend..Iadd.42. The litter box of claim 41 wherein said sensor system includes a source of radiation and a radiation detector..Iaddend..Iadd.43. A self-cleaning cat litter box comprising: a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a comb drive coupled to the housing;   a comb extending between two opposed sidewalls and being coupled to the comb drive and movable between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   a mode selector switch, the switch being moveable between a manual operation position wherein an operator causes the comb to move toward the discharge position and an automatic operation position wherein the comb moves toward the discharge position automatically upon the occurrence of a predetermined event; and   wherein said comb drive is operated on a cyclical basis when said mode selector switch is in said manual operation position..Iaddend..Iadd.44. A self-cleaning cat litter box comprising:   a pan-shaped housing defining an upwardly open litter chamber to be filled to a given fill level with cat litter;   a waste receptacle located outside the litter chamber;   a comb disposed in the litter chamber;   comb drive means for driving the comb between a storage position and a discharge position, the comb projecting down into the litter chamber to a level below the fill level while the comb moves toward the discharge position so that the comb engages clumps in the litter and moves such clumps toward the discharge position; and   a waste level sensor coupled to the litter chamber; and   wherein said cat litter box further includes an alarm coupled to the waste level sensor, the alarm being activated when the waste level sensor determines that waste in the waste receptacle has reached a predetermined level; and   wherein said waste level sensor includes a source of radiation and a radiation detector..Iaddend..Iadd.45. The litter box of claim 44 wherein said source and said detector are located such that waste at said predetermined level is between said source and said detector..Iaddend..Iadd.46. A self-cleaning cat litter box comprising:   a housing defining a litter chamber to be filled to a fill level with cat litter, said housing having first and second ends, said litter chamber being located between said first and second ends; and   a device for engaging clumps in the litter, said device being coupled to the housing, said device being movable between a storage position and a discharge position, said storage position being located at said first end of said housing, said discharge position being located at said second end of said housing, and wherein said device projects into said litter chamber to a level below the fill level so that the device engages clumps in the litter and moves such clumps toward the discharge position, and wherein said device is positioned above the fill level in said storage position..Iaddend..Iadd.47. The litter box of claim 46 wherein said device includes tines arranged to move through the cat litter in said litter chamber, said tines being located above the fill level when said device is in said storage position..Iaddend..Iadd.48. The litter box of claim 47 further comprising a track extension for removing said tines from the cat litter as said device moves toward said storage position..Iaddend.