Abstract:
A vacuum cleaner includes a device for dispensing atomized liquid, the device having a reservoir for holding liquid and an ultrasonic transducer arranged to atomize the liquid in the reservoir. An airflow is created through the reservoir via the exhaust gasflow from the vacuum cleaner, the airflow carrying the atomized liquid via an elongate tube to dispensing outlet provided on a cleaning head of the vacuum cleaner. The ultrasonic transducer is simple and inexpensive, yet is able to reliably atomize the liquid for dispensing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit from UK Application No. 1003750.5, filed Mar. 8, 2010, and UK Application No. 1009084.3, filed Jun. 1, 2010, both of which are hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to vacuum cleaners incorporating means for dispensing atomized liquids into the atmosphere or onto the surface being cleaned. 
     2. Related Background Art 
     When cleaning floors and other surfaces, its often desirable to dispense fluid onto the surface, which freshens, disinfects or otherwise treats the surface being cleaned. 
     Vacuum cleaners are known which incorporate means for dispensing atomized liquids onto the surface being cleaned. Once such vacuum cleaner is disclosed in GB2436786 and comprises an aerosol, which is mounted on the cleaning wand and which can be actuated to spray liquids onto the surface being cleaned. Such aerosols are expensive to purchase and are harmful to the environment. Accordingly, an alternative way of atomising liquids is needed. 
     It is known to use heat to atomize liquids. However, the use of heat in a domestic vacuum cleaner is undesirable, since it increases energy consumption and creates a potential fire risk. Also, heated liquid can harm the surface being cleaned. Other known devices for atomising liquid can be difficult to control and hence can over wet the surface being cleaned. 
     Accordingly, an object of the present invention is to provide a vacuum cleaner which solves the above-mentioned problems. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, as seen from a first aspect, there is provided a vacuum cleaner comprising a device for dispensing atomized liquid, the device comprising a reservoir for holding liquid and an ultrasonic transducer arranged to atomize the liquid in the reservoir, the vacuum cleaner further comprising means for creating an airflow through the reservoir to carry the atomized liquid to a dispensing outlet of the vacuum cleaner. 
     The ultrasonic transducer creates a mist of liquid, which is then conveyed into the atmosphere or onto the surface being cleaned by the airflow. Ultrasonic transducers consume very little power and are inexpensive in construction. Furthermore, the frequency and/or amplitude of the output of the ultrasonic transducer can preferably be controlled to vary the quantity of liquid being dispensed. The use of an ultrasonic transducer also avoids the need for any heating devices or pumps to atomize the liquid. 
     Preferably said means for creating an airflow through the reservoir comprises a fan, which is primarily arranged to draw air from a cleaning head through a dust separation device of the cleaner and to exhaust clean air into the atmosphere. 
     Preferably the reservoir comprises an air inlet connected to a point downstream of said fan, such as a point at or adjacent an exhaust outlet for said cleaned air. 
     It will be appreciated that the use of exhaust from the vacuum cleaner enables an airflow to be created through the reservoir in a simple manner and without the need for an additional fan. The use of exhaust in this way also avoids consumption of increased power. 
     Preferably the ultrasonic transducer is disposed on the bottom wall of the reservoir, so that substantially all of the liquid in the reservoir can be dispensed. 
     Preferably the reservoir can be refilled with liquid, for example by opening a closure provided on a wall of the reservoir. 
     Preferably said airflow is directed over the surface of the liquid in the reservoir, so as to carry away the layer of atomized liquid particles existing above the liquid. 
     Preferably the reservoir comprises a boundary wall which divides the reservoir into two compartments, the boundary wall terminating above the liquid in the reservoir, such that air supplied to one compartment passes under the boundary wall into the other compartment and over the surface of the liquid. 
     Preferably the dispensing outlet is positioned adjacent a suction inlet of the cleaner, so that the reduced pressure created by the suction adjacent the dispensing outlet further serves to enhance the airflow through the reservoir. 
     Preferably the reservoir is mounted on the body of the cleaner, the dispensing device further comprising an elongate duct for conveying the airflow out of the reservoir to said dispensing outlet. 
     Preferably said duct extends along or inside an elongate flexible duct arranged to carry dirty air from the cleaning head of the vacuum cleaner into the body of the vacuum cleaner. 
     Preferably said dispensing outlet is disposed on the cleaning head and is arranged to direct atomized liquid onto the surface being cleaned. 
     Preferably said dispensing outlet comprises a plurality of apertures. 
     It is also envisaged that the atomizer may be provided as an accessory for fitting to existing vacuum cleaners. Accordingly, in accordance with the present invention, as seen from a second aspect, there is provided a liquid atomizer device for fitting to a vacuum cleaner, the device comprising a reservoir for holding liquid and an ultrasonic transducer arranged to atomize the liquid in the reservoir, the reservoir having an air inlet and an air outlet arranged such that an airflow through the reservoir conveys the atomized liquid to a surface being cleaned. 
     Preferably the device comprises a cleaning head for fitting to the vacuum cleaner, the head having a suction inlet connected to an outlet port for coupling to an elongate wand or hose which conveys the air to the body of the cleaner. 
     Preferably the head comprises a dispensing outlet for the atomized liquid connected to said air outlet of the reservoir. 
     Preferably said dispensing outlet is disposed adjacent said suction inlet so that the reduced pressure created by the suction adjacent the dispensing outlet creates said airflow through the reservoir. 
     Preferably, the suction inlet is disposed in a bottom wall of the head, the dispensing outlet being disposed on a front wall of the head and is preferably directed downwardly such that atomized liquid is directed onto the floor surface being cleaned. 
     Preferably said dispensing outlet comprises a plurality of apertures. 
     Preferably the device comprises a battery for energising said ultrasonic transducer. 
     Preferably the device comprises an actuator for varying the frequency and/or amplitude of the output of the ultrasonic transducer to vary the quantity of liquid being dispensed. 
     Preferably the ultrasonic transducer is disposed on a bottom wall of the reservoir, so that substantially all of the liquid in the reservoir can be dispensed. 
     Preferably the reservoir can be refilled with liquid, for example by opening a closure provided on the device. 
     Preferably said reservoir is arranged to direct the airflow over the surface of the liquid therein, so as to carry away the layer of atomized liquid particles existing above the liquid. 
     Preferably the reservoir comprises a boundary wall which divides the reservoir into two compartments, the boundary wall terminating above the liquid in the reservoir, such that air entering one compartment from the air inlet passes under the boundary wall into the other compartment and over the surface of the liquid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic side view of a vacuum cleaner in accordance with the first aspect of the present invention; 
         FIG. 2  is a sectional view through a dispensing device of the vacuum cleaner of  FIG. 1 ; 
         FIG. 3  is a perspective view of a cleaning head in accordance with the second aspect of the present invention; and 
         FIG. 4  is a sectional view through the head of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  of the drawings, there is shown a vacuum cleaner of the so-called cylinder type, which comprises a body  10  connected to a floor cleaning head  11  via an elongate flexible tube  12  and a rigid wand  13 . In use, dirty air is drawn through a suction inlet  14  in the underside of the cleaning head  11 , whereupon it travels along the wand  13  and flexible hose  12  into the body  10  of the cleaner. The dirty air is then drawn through a dust separation device  15  by a motor/fan unit  16 . The cleaned air is then output into the atmosphere through an exhaust duct  17 . 
     It will be appreciated that the vacuum cleaner as hereinbefore described is a conventional vacuum cleaner. However, in accordance with the present invention, the vacuum cleaner further comprises a dispensing device for dispensing cleaning liquids or other liquid treatments onto the surface being cleaned. The dispensing device comprises a reservoir  18  mounted in or on the body  10  of the vacuum cleaner. 
     Referring also to  FIG. 2  of the drawings, the reservoir  18  comprises an air inlet  24  at its upper end, which is connected to the exhaust duct  17  of the vacuum cleaner by a tube  19 . The reservoir  18  also comprises an air outlet duct  25 , which connected to the cleaning head  11  of the vacuum cleaner by an elongate flexible tube  20 , which extends along the flexible hose  12  and rigid wand  13  to dispensing outlet  28  provided on the front wall of the cleaning head  11 . Preferably the tube  20  extends inside the flexible hose and wand  13  so that it is hidden from view. It may also extend inside the body  10  of the vacuum cleaner, rather than externally as shown. 
     The reservoir  18  comprises a tubular sidewall  23 , which is closed at its upper end by a removable closure  21  on which the inlet  24  is provided. An ultrasonic transducer  22  is mounted across an opening formed in the bottom wall of the reservoir  18 . The reservoir  18  is divided into two longitudinally-extending compartments  29 , 30  by a boundary wall  26 . The boundary wall  26  seals against the closure  21  at its upper end and terminates at its lower end at a point above the uppermost fluid fill level in the reservoir  18 . 
     In use, when the vacuum cleaner is operating, a portion of the pressurised air in the exhaust duct  17  flows along the tube  19  into the first compartment  29  of the reservoir  18 . The ultrasonic transducer  22  is energised by a signal sufficient to cause vibrations in the liquid  27 , which create a layer of atomized liquid particles over the surface of the liquid  27  in the reservoir  18 . The airflow into the first compartment  29  of the reservoir  18  then passes under the boundary wall  26  and over the surface of the liquid  27  in the reservoir  18 , so as to carry the layer of atomized liquid particles existing above the liquid  27  into the second compartment  30  of the reservoir  18  and along the elongate pipe  20  to the cleaning head  11 . The dispensing outlet  28  on the cleaning head  11  then directs the atomized liquid onto the surface being cleaned. The dispensing  28  outlet is positioned adjacent a suction inlet  14  of the cleaner, so that the reduced pressure created by the suction adjacent the dispensing outlet  28  further serves to enhance the airflow through the reservoir  18 . 
     The ultrasonic transducer  22  is controlled by a control circuit  31 , which is preferably provided with an actuator, which can be controlled by a user to turn the dispensing device on and off and to control the amount of liquid being dispensed. 
     Referring to  FIGS. 3 and 4  of the drawings, there is shown a cleaning head  111  for fitting to the elongate wand  113  of a conventional vacuum cleaner. The head  111  comprises a front wall  120 , opposite side walls  121 , a rear wall  122 , a top wall  123  and a bottom wall  124 . A suction inlet  114  extends transverse the bottom wall  124 , the inlet  114  being connected via an internal duct (not shown) to a port  125  extending rearwardly from the rear wall  122  and arranged for coupling with the distal end of the elongate wand  113 . 
     A plurality of downwardly-directed dispensing outlets  128  are arranged in line across the front wall  120 . A reservoir  118  of the kind shown in  FIG. 2  is disposed inside the head  111  and like parts are given like reference numerals. In this embodiment the closure  131  is positioned above the top wall  123  of the head  111  for easy filling of the reservoir  118 . The closure  131  is provided with a series of small apertures  129  which take the place of the air inlet port  24  in  FIG. 2 , although it will be appreciated that an air inlet could be provided in the upper side wall of the compartment  29 . The air outlet port  25  is connected via a pipe  116  directly to the dispensing outlets  128 . 
     The ultrasonic transducer  22  is controlled by the control circuit  31 , which is connected to an actuator  119  on the top wall  123  that is arranged to be controlled by a user to turn the dispensing device on and off and to control the amount of liquid being dispensed. The control circuit  31  is powered by a battery  117 . 
     In use, when the device  111  is fitted to a vacuum cleaner and the cleaner is energised, the reduced pressure created by the suction applied to the suction inlet  114  adjacent the dispensing outlet  28  creates an airflow through the reservoir  118 . The atomized liquid are drawn from the reservoir  118  along the pipe  116  to the dispensing outlet  128 , which directs jets  109  of the atomized liquid onto the surface being cleaned. 
     It will be appreciated that the vacuum cleaner in accordance with the first aspect of the present invention can thus be provided by fitting a device in accordance with the second aspect of the present invention to a conventional vacuum cleaner. The present invention thus provides a simple and inexpensive way to reliably dispense controlled amounts of atomized liquid onto the surface being cleaned by a vacuum cleaner. 
     While the preferred embodiment of the invention has been shown and described, it will be understood by those skilled in the art that changes of modifications may be made thereto without departing from the true spirit and scope of the invention.