Abstract:
The invention provides a vacuum cleaner ( 10 ) having a chassis ( 12 ), supporting wheels ( 14 ) mounted on the chassis ( 12 ), drive means ( 15 ) connected to the supporting wheels ( 14 ) for driving the supporting wheels ( 14 ) and a control mechanism for controlling the drive means ( 15 ) so as to guide the vacuum cleaner ( 10 ) across a surface to be cleaned. A cleaner head ( 22 ) having a dirty air inlet ( 24 ) facing the surface to be cleaned is mounted on the chassis ( 12 ) and separating apparatus ( 52 ) is supported by the chassis ( 12 ) and communicates with the cleaner head ( 22 ) for separating dirt and dust from an airflow entering the vacuum cleaner ( 10 ) by way of the dirty air inlet ( 24 ). The separating apparatus ( 52 ) comprises at least one cyclone( 54,56 ). This type of separating apparatus is not prone to clogging and therefore the pick-up capability of the cleaner ( 10 ) is maintained at a high standard.

Description:
This application claims priority to International Application No. PCT/GB99/04077 which was published on Jun. 29, 2000. 
     1. Field of the Invention 
     The invention relates to a vacuum cleaner particularly, but not exclusively, to an autonomous or robotic vacuum cleaner. 
     2. Background of the Invention 
     Various proposals have been made in respect of autonomous or robotic vacuum cleaners, which are driven automatically and do not require to be propelled by a user across a surface to be cleaned. Essentially, such a vacuum cleaner comprises a body or chassis supported on wheels which are driven by a self-contained power pack and guided by a control system which navigates the vacuum cleaner around a room so that the floor or floor covering can be cleaned. For this purpose, the cleaner will also incorporate a cleaner head having a suction opening communicating with a dirt or dust collection device so that dirt and dust can be sucked up from the surface to be cleaned, separated from the airflow and stored in a container for disposal. Devices of this nature are shown and described in WO 97/40734 and WO 97/41451. 
     One of the disadvantages associated with devices of this type is that, in order for the machine to be able to manoeuvre into and out of small spaces, the device preferably has an essentially circular shape when seen in plan view. This allows the device to rotate about its own vertical axis when it has entered a restricted area so that it can turn around and locate a way out. Since any protrusion beyond the circular shape of the body will restrict the manoeuvreability of the device, the suction opening of the cleaner head is inevitably spaced away from the lateral extremity of the cleaner. This means that, when the cleaner is vacuuming along a wall or other edge of the area to be cleaned, the brush housed within the cleaner head cannot get as close to the wall or edge as existing vacuum cleaners which are manoeuvred by a user. 
     It is an object of the present invention to provide a vacuum cleaner of the type described above which can operate in close proximity to a wall or other edge. It is another object of the present invention to provide a vacuum cleaner of the type described above which can operate in close proximity to a wall or other edge without restricting the manoeuvrability of the vacuum cleaner. It is a further object of the present invention to provide a vacuum cleaner of the type described above which is capable of manoeuvring past small obstacles without becoming lodged. It is a further object of the present invention to provide a vacuum cleaner of the type described above which is capable of cleaning a larger proportion of the surface to be cleaned than known vacuum cleaners of this type. 
     SUMMARY OF THE INVENTION 
     The invention provides a vacuum cleaner comprising a body having supporting wheels, drive means for driving the wheels so as to propel the vacuum cleaner in a direction across a surface to be cleaned, dust and dirt separating apparatus and a fan for drawing air into the dust and dirt separating apparatus, the vacuum cleaner also having a cleaner head mounted beneath the body, transversely to said direction, and incorporating a dirty air inlet facing the surface to be cleaned, characterised in that the cleaner head protrudes transversely beyond the body on at least one side of the vacuum cleaner. 
     Providing a cleaner head which protrudes transversely beyond the body on at least one side of the vacuum cleaner means that, at least on the side on which the cleaner head protrudes, the vacuum cleaner is able to clean closer to a wall or other obstacle than previously known vacuum cleaners of the type described above. This arrangement provides a higher standard of cleaning than known vacuum cleaners and increases the product satisfaction of consumers. 
     In a preferred embodiment, the cleaner head is movable transversely with respect to the body so as to reduce or eliminate the protrusion thereof beyond the body. This arrangement allows the cleaner head to be retracted beneath the body of the vacuum cleaner so that, if the vacuum cleaner is required to manoeuvre within a confined area, the protruding cleaner head does not restrict the manoeuvreability of the vacuum cleaner. The transverse moveability of the cleaner head also allows the cleaner head to retract when small obstacles are located within the path of the cleaner head and this avoids the need to divert the whole vacuum cleaner from its previous direction of travel. 
     This arrangement is particularly advantageous for cleaners which have a body that is substantially circular in plan view. However, it can also be used on cleaners having bodies which are not circular. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other preferred features are set out in the subsidiary claims. Further advantages of the features of the invention will become clear from the following description. A preferred embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, wherein: 
     FIG. 1 is a side view of a first embodiment of an autonomous or robotic vacuum cleaner according to the invention: 
     FIG. 2 is a side view of the cleaner of FIG. 1 with the driven wheel omitted for clarity; 
     FIG. 3 is an underneath view of the cleaner of FIG. 1; 
     FIG. 4 is an underneath view of a first alternative embodiment according to the invention; 
     FIG. 5 is a schematic underneath view of a second alternative embodiment according to the invention; and 
     FIG. 6 is a schematic underneath view of a third alternative embodiment according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The vacuum cleaner  10  shown in FIGS. 1 to  3  of the accompanying drawings is designed to be autonomous or robotic. The vacuum cleaner  10  is thereby able to operate without any propulsion from a user. Essentially, it consists of a generally circular chassis  12  supported by two wheels  14  which are arranged diametrically opposite one another and rotatable about an axis  16  arranged perpendicular to the normal direction of motion of the vacuum cleaner  10  indicated by arrow  17 . The chassis  12  carries separate motors  18  for driving each wheel  14 , either in the same direction for forward motion or in opposite directions to allow the cleaner  10  to revolve about its own vertical axis  20 . The motors can also be driven at different speeds in order to allow the cleaner  10  to turn corners. Sensors (not shown) are provided on the chassis  12  or on a housing of the vacuum cleaner (not shown) in order to allow the vacuum cleaner  10  to detect the proximity of walls, furniture and obstacles in its path. Control means operable in response to the output of the sensors operate the motors  18  to drive the wheels  14  over a surface to be cleaned whilst avoiding obstacles. However, the sensors and control means do not form part of the present invention and will not be described any further here. A trailing castor wheel  22  is provided centrally at the rear of the chassis  12  to provide additional support for the vacuum cleaner  10 . 
     The vacuum cleaner  10  also supports a motor and fan unit  24  connected to dirt and dust separating apparatus  26  arranged on the chassis  12 . In this embodiment, the dirt and dust separating apparatus  26  consist of a cyclonic separator comprising two cyclones arranged in series. The configuration of such separating apparatus is well known and will not be described any further here, save to say that the apparatus  26  is removably attached to the chassis  12  by means of resilient, quick-release fasteners to allow for emptying of the apparatus  26  when it becomes full. However, the nature of the dirt and dust separating apparatus  26  is not important to the present invention and the cyclonic separator can if desired be replaced by a conventional bag filter. The inlet to the dirt and dust separating apparatus  26  is connected via a flexible pipe  28  to a brush housing  30  forming part of a cleaner head  32 . The cleaner head  32  is arranged beneath the rear part of the chassis  12  and the brush housing  30  is connected to the chassis  12  by means of two parallel elongate arms  34 . The brush housing  30  incorporates a suction opening  36  which faces downward towards the surface to be cleaned. The cleaner head  32  is freely pivotable with respect to the chassis  12  so that, in use, the brush housing  30  floats on the surface to be cleaned and is maintained in contact therewith by virtue of its own mass. This enables the brush housing  30  to lift away from the surface to be cleaned in the event of a small obstacle being encountered during the cleaning operation without the entire weight of the cleaner  10  having to be lifted. 
     The chassis  12  also carries two power packs  38  in the from of rechargeable batteries. The batteries  38  are removably attached to the chassis  12  to allow the user to transport them to a recharging station between cleaning sessions. When the batteries  38  are charged and affixed to the chassis  12 , connections provide for power to be supplied to the drive motors  18 , to the sensors and control means which navigate the cleaner  10 , and to the motor and fan unit  24  which draws dirty air into the dirt and dust separating apparatus  26  via the brush housing  30 . This allows the cleaner  10  to navigate around a room or other defined area to vacuum the floor or floor covering without bumping into obstacles. 
     As can be seen from FIG. 3, the brush housing  30  is mounted so that one end thereof  30   a  protrudes beyond the chassis  12  and, indeed, beyond the outer extremity of the supporting wheel  14  on the side of the cleaner  10  on which the brush housing  30  protrudes. In this way, the brush housing  30  can approach a wall or obstacle alongside which the vacuum cleaner  10  is moving so that cleaning can take place very close to that wall or obstacle. This arrangement is highly advantageous in that the standard of cleaning coverage achieved by the vacuum cleaner  10  is very high. Because the end  30   a  of the brush housing  30  can often be required to travel along a wall or other fixed obstacle whilst in contact therewith, vertically mounted wheels or rollers  40  are provided at the distal end of the brush housing  30  to allow rolling contact with an obstacle in order that the risk of any damage thereto is minimised. The presence of the wheels or rollers  40  prevents the end  30   a  of the brush housing  30  from scraping along the wall and causing damage thereto. 
     The elongate members  34  by means of which the brush housing  30  is mounted on the chassis  12  are inclined at a small angle of inclination to the horizontal and extend generally parallel to the surface to be cleaned and to the lower surface of the chassis  12 . The elongate members  34  are fixedly connected to or formed integrally with the brush housing  30  and connected to the chassis  12  by means of pivoting joints  42  which allow the elongate members  34  to pivot within a vertical plane about the joints  42  so that the brush housing  30  is able to move in a vertical direction with respect to the surface to be cleaned. Sufficient clearance is allowed between the underside of the chassis  12  and the brush housing  30  to allow vertical movement of the brush housing  30  with respect to the chassis and, within certain limits, this can be achieved by providing appropriate shaping in the underside of the chassis  12 . The intention is to allow the brush housing  30  to travel or “float” over small obstacles, such as electric cables, rugs, books or papers lying on the surface to be cleaned, without the cleaner head  32  having to lift the entire mass of the vacuum cleaner  10 . The advantage of such an arrangement is that the cleaner does not need to be deviated from its desired path more often than is necessary. 
     A second embodiment of a vacuum cleaner according to the invention is illustrated in FIG.  4 . The Figure shows an underneath view of the cleaner, similar to FIG.  3 . Corresponding components have been given reference numerals identical to those used in FIGS. 1 to  3 . The only significant difference between the embodiments of FIGS. 1 to  3  and FIG. 4 is the arrangement by means of which the cleaner head  32  is mounted on the chassis  12 . In this second embodiment, the cleaner head  32  is mounted so that, in addition to the vertical movement of the brush housing  30  allowed by pivotal movement of the elongate members  34  in a vertical plane about pivoting joints  42   a , the cleaner head  32  is also able to move transversely with respect to the chassis  12 . This is achieved by making use of universal or similar joints  42   a ,  42   b  at either end of each elongate member  34  to connect the elongate members  34  to the chassis and the brush housing respectively. Ball joints are suitable but any other joint or combination of joints which allows the elongate member  34  to pivot, within predetermined limits, within both a vertical plane and a horizontal plane will be adequate. 
     The ability of the brush housing  30  to move in a vertical plane has the same effect and advantage as that described above. However, the ability of the brush housing  30  to move in a direction transverse to the normal direction of travel of the vacuum cleaner  10  gives an added advantage of the second embodiment over the first. The transverse movement of the brush housing  30  allows the protruding brush housing  32  to “retract” in the event that an obstacle is encountered on which, if the transverse movement were not allowed, the brush housing  30  would become lodged, but which is sufficiently small that the main body of the vacuum cleaner would be allowed to pass if the brush housing  30  did not protrude. Should the brush housing  30  encounter such an obstacle, the brush housing  30  is merely pushed inwardly so that the protruding end  30   a  is retracted towards the main body of the vacuum cleaner  10 . The cleaner  10  can then proceed along its original path without requiring the entire mass of the body to be deflected, which would require additional energy consumption. 
     The wheels or rollers  40  arranged on the protruding end  30   a  of the brush housing  30  assist greatly in allowing the brush housing  30  to move transversely in the event that an obstacle is encountered. The outermost portions of the wheels or rollers  40  come into direct contact with the obstacle and “roll around” the obstacle so that the brush housing  30  does not become lodged. 
     The underside of the chassis  12  is shaped so as to include recesses  44  which allow the elongate members  34  to pivot within certain limits about joints  42   a  within a horizontal plane. The recesses  44  can be used to prevent the brush housing  30  from moving beyond a specified limit by causing the elongate members  34  to abut against the sides of the recesses and thereby prevent further movement. 
     Biasing means in the form of a compression spring  46  are provided in order to bias the brush housing  30  into the position shown in FIG.  4 . However, the biasing force is designed to be low enough not to present any significant hindrance to the transverse movement of the brush housing  30  when an obstacle is encountered. Under the influence of the biasing means  46 , the brush housing  30  is normally maintained in its protruding position but can easily be retracted against the biasing force in the event that an obstacle is encountered. The biasing means can take any form suitable for biasing the brush housing into the position shown in FIG.  4 : alternatives to the illustrated compression spring are elastomeric bands, foamed plastic blocks and other resilient components designed to bias the brush housing into the protruding position. 
     The embodiment illustrated in bold lines in FIG. 4 has a brush housing  30  which extends, on the side opposite to the protruding end  30   a , to the same extent as it would if the protruding end  30   a  did not protrude, i.e. as far as the general circular outline of the cleaner  10 . However, in an alternative embodiment illustrated in FIG. 5, the non-protruding end  30   b  of the brush housing  30  is shortened so that, when the protruding end  30   a  is retracted back under the chassis  12 , the non-protruding end  30   b  remains substantially within the circle defined by the chassis  12  and the rear castor  22 . In the event that the vacuum cleaner  10  becomes trapped in a very restricted area and requires to turn about its own vertical axis in order to exit the confined area, the brush housing  30  can be retracted almost completely beneath the chassis  12  of the vacuum cleaner  10  so that it does not protrude to any significant extent. In this way, the vacuum cleaner&#39;s manoeuvreability is not compromised. The cleaner  10  illustrated in FIG. 5 utilises a tension spring  46   a  acting between one of the elongate members  34  and an appropriate portion of the chassis  12  as the biasing means. 
     In a further alternative embodiment of the invention, the brush housing  30  is mounted on a generally triangular plate  34   a  by way of a single universal or similar joint  42   c . The joint  42   c  allows the brush housing  30  to move in a vertical plane to ride or float over small obstacles on the floor as described above and also to pivot about the joint  42   c  in a horizontal plane as illustrated by the arrow  48  in FIG.  6 . The protruding end  30   a  of the brush housing  30  is able to move back under the chassis  12  in a swinging motion when a small obstacle is encountered by the end  30   a  of the brush housing  30 . The swinging motion is opposed by a small block of resilient foamed plastic  46   c  which is affixed to the underside of the chassis  12 . The block  46   c  biases the triangular plate  34   a  into the position shown in FIG. 6 in which the end  30   a  of the brush housing  30  protrudes beyond the lateral extremity of the vacuum cleaner  10 . 
     In operation, the vacuum cleaner  10  is propelled under its own power supplied by the rechargeable batteries  38  across a surface to be cleaned. The drive motors  18  drive the wheels  14  across the surface guided by the control system and sensing equipment. In its normal mode of operation, the vacuum cleaner  10  will travel around the area to be cleaned in such a way that the protruding side of the brush housing  30  is always directed towards an obstacle around which the vacuum cleaner  10  is to navigate. For example, if the vacuum cleaner  10  is to circumnavigate a room keeping close to the walls, the vacuum cleaner  10  will locate itself so that the protruding end  30   a  of the brush housing  30  comes as close as possible to the said walls. If the vacuum cleaner  10  encounters a small obstacle protruding into the room, the brush housing  30  can retract automatically under the chassis  12  to allow the cleaner to continue moving in a substantially straight line whilst the object is passed. The retractability of the brush housing  30  also assists when the vacuum cleaner  10  is turning around corners because the extremity of the corner can be regarded as a small obstacle. The retractability of the brush housing  30  under the chassis  12  will ensure that the area around the corner will be cleaned to the maximum extent possible. 
     A rotating brush bar is mounted within the brush housing  30  so as to protrude slightly through the suction opening  36  in the normal way. The brush bar is driven by any suitable means, preferably by a separate motor carried by the cleaning head  32 . 
     The invention is not limited to the specific features of the embodiment described above. If desired, the brush housing  30  of the cleaner head  32  can be arranged to protrude on both sides of the chassis  12  to allow close-to-the-edge cleaning on both sides of the cleaner  10 . Such an arrangement would compromise the vacuum cleaner&#39;s manouevreability, but may be satisfactory in many applications. The cleaner head  32  could then be made to be moveable transversely in either direction in order to be able to accommodate obstacles located on either side of the vacuum cleaner. Other modifications and variations will be apparent to a skilled reader.