Self-cleaning litter box

Details Self-cleaning litter box Self-cleaning litter box

1999-10-04

2001-09-11

Jordan, Charles T. (Department: 3644)

Animal husbandry

Waste toilet or related device

Walled receptacle; e.g., litter box, etc., containing...

C119S161000, C119S163000

Reexamination Certificate

active

06286457

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an indoor portable self-cleaning litter-box for domestic pets. In particular, this invention relates to a device having means for automatically filtering and separating clumped soiled litter and fecal matter from clean litter.
BACKGROUND OF THE INVENTION
Litter boxes for domestic pets, more especially for cats, are well known. The most common and oldest prior art is the traditional “sandbox”. A box, of any material, is filled with sand and placed in the household. To dispose of soiled litter and fecal matter the sandbox the sandbox is emptied manually. Perforated or slotted scoops have since been developed as a means to remove soiled litter and fecal matter. As well, the introduction of “clumping” litter that, when soiled, clumps together has increased the effectiveness of the perforated or slotted scoop for removing soiled litter. However, given that while the majority of the soiled litter and fecal matter may be removed by means previously described, the entire contents of the sandbox or litter box must be emptied and disposed of from time to time. Typically, both the cleaning and changing of litter requires significant human contact with the litter. Contact with domestic pet waste, cat urine in particular, is potentially very dangerous for pregnant women and has been known to cause miscarriages. In addition, the odour associated with domestic pet waste can be particularly offensive and in some cases may cause nausea. More recently, chambers have been introduced in an attempt to overcome the aforementioned problems. Numerous configurations using a chamber, a filter, and disposable means, allow for a more contained litter box which may be rotatable. The filter essentially replaces the perforated or slotted scoop and is mounted on the inner wall of the chamber and acts to separate the waste material from the clean litter. Limitations of the prior art encompass filter difficulty in terms of retaining waste material on the filter and the absence of a simple means for the addition of clean litter.
A self-cleaning litter box in keeping with the present invention avoids the previously described limitations of the prior art. A self-cleaning litter box such as this comprises a rotatable drum, a spiral filter, a stationary back plate, drive means, and switch means. The cylindrical drum has both front and back walls, an axis of rotation, and support means. The spiral filter is mounted on the inner surface of the drum and at least 10° from the bottommost point of the drum when at its rest position. The filter effectively scoops clumped soiled litter and fecal matter from the bottommost region of the rotating drum and collects the waste material on the filter. There is a first opening in the back wall of the drum and second and third openings in the back plate. When the first and second openings are aligned, it allows passage of clumped soiled litter and fecal matter collected by the filter into disposable means through the aligned openings. When the first and third openings are aligned, clean litter from a reservoir may be dispensed into the drum through the aligned openings.
DESCRIPTION OF THE PRIOR ART
U.S. Pat. No. 4,120,264 issued to CARTER teaches a rotatable enclosure or chamber. The rotatable enclosure contains two filter segments wherein soiled agglomerated litter and solid animal excrement are separated from particulate litter. When the drum is rotated, the leading filter segment contacts the litter and filters the material through the filtering grate. As the drum continues to rotate the majority of the litter passes through the filter. The waste material is retained on the first filter segment and is forced by gravity and the incline of the filter toward the second filter segment and the back of the drum. The soiled litter is expelled from the drum via a chute into a disposable bag. The rotatable enclosure is manual in operation, whereby for rotation to occur the litter box owner must rotate it.
U.S. Pat. No. 4,522,150 issued to GERSHMAN teaches an enclosure that is rotated 360° wherein the entire mass of litter passes through a screen and the soiled litter is trapped in a drawer-like container which may be removed in order to dispose of the soiled litter. The rotation is again manual and requires the litter box owner to perform the rotation.
PIERSON, U.S. Pat. No. 4,846,104 provides a rotatable enclosure for use as a litter box for domestic animals. The enclosure contains litter, and rotation of the enclosure cleans the litter by passing the litter through a screen, and the collected waste material is deposited in a receptacle. The particular relevance of this patent is that when cleaning is desired the rotation process itself is not manual and may be initiated by a push button control and timer.
LAROCHE, U.S. Pat. No. 5,107,797 teaches a rotatable enclosure wherein a motor rotates the enclosure and a rake located on the interior surface of the enclosure passes through the litter and effectively separates soiled litter from clean litter. Collected waste material is deposited into a receptacle.
U.S. Pat. No. 5,477,812 issued to WATERS teaches an improved automated self-cleaning litter box for cats, wherein the improvement includes a sensor for sensing the presence of a cat in the litter chamber. Once the cat leaves the litter chamber there is a pre-set time delay that is set into the micro-control. This time interval may be varied and is intended to allow for a period of time wherein the cat may return to the litter box. Once the delay period is over, the self-cleaning operation begins automatically. The litter box is rectangular in shape and uses an automated rake device as it cleaning mechanism.
U.S. Pat. No. 5,509,379 issued to HOESCHEN provides a rotating cylinder with an internal surface for receiving animal litter and waste materials. This cylinder employs a series of rollers along the base in order for facilitate rotation. As the cylinder rotates within the base, the litter and animal waste falls onto a separation screen. As the rotation continues, the clean litter passes through the screen, and the waste supported on the screen is removed by a collection assembly.
PAGE, U.S. Pat. No. 5,752,465 teaches a rotatable drum which uses a sieving panel to isolate solid and clumped litter from particulate litter. A funnel region present on the interior wall directs waste material to a chute adapted to hold a disposable plastic bag.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a self-cleaning litter box.
The apparatus comprises a rotatable drum being cylindrical and adapted to contain litter. The drum itself having front and back walls, an axis of rotation and support means. There is a spiral filter mounted on the inner surface of the drum, a stationary back plate, drive means, and switch means.
The rotatable drum has a front opening in the front wall which serves as an access and egress suitable for a domestic pet to pass through. There is provided a first opening in the back wall for both the removal of soiled litter and the addition of clean litter.
The axis of rotation of the drum is located along the centre line and passes longitudinally through the drum. The drum is symmetric about its axis of rotation and is rotatably mounted on the support means which comprise at least two bearings. These bearings facilitate the rotation of the drum.
The stationary back plate is both parallel to the plane of the back wall and flush with the back wall of the drum. There is a second opening in the back plate that permits the passage of clumped soiled litter and fecal matter away from the drum. The back plate also has a third opening, at least 180° from the second opening, that allows the passage of clean litter in to the drum. At least a portion of the second opening in the back plate is substantially in the same plane as the axis of rotation of the drum.
The filter spans the length of the drum and at least 180° of the inner surface of the drum. The spiral angle of the filter is between

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