Patent Publication Number: US-2007101536-A1

Title: Twin-motor independent vacuum cleaner

Description:
The invention relates to a cordless vacuum cleaner that cleans very effectively.  
      More precisely, the invention relates to a cordless vacuum cleaner comprising a structure mounted on transport members, a turbine carried by the structure for creating suction in a particle collector via a filter membrane, a beater brush secured to the structure and connected to said collector via a first duct, a suction device suitable for being connected to said collector via a flexible second duct, means for selectively putting said first duct or the coupling for said second duct into communication with said collector, a first motor (M 1 ) for driving said turbine, a second motor (M 2 ) for driving the beater brush, an electrical circuit for powering said motors from a battery carried by said structure, and a three-position control member serving in a first position to stop the motors, in a second position to cause the first motor (M 1 ) to operate, and in a third position to cause both motors (M 1 , M 2 ) to operate simultaneously.  
      Such a vacuum cleaner having two direct current (DC) motors is described in WO 03/003896. In that type of vacuum cleaner, the two motors are connected in parallel to the terminals of the battery and each of them is controlled by a two-position switch. The performance of the turbine depends on the extent to which the filter membrane is clogged. When the collector is filled with particles, cleaning effectiveness is greatly decreased. To remedy that, the motors driving the turbine and the beater brush are fitted with electronic circuits that are complex and expensive.  
      One of the objects of the invention is to propose a cordless vacuum cleaner of the type mentioned in the introduction of the present specification, in which the voltage applied to the terminals of the two motors adapts automatically when operating in beater mode, as a function of the degree to which the filter membrane is clogged, without the presence of electronic circuits.  
      The invention achieves this object by the fact that the motors are electrically powered in such a manner that when the control member is in the third position, the two motors are powered in series.  
      Surprisingly, it is found that when the collector becomes clogged, the voltage across the turbine drive motor increases and the voltage across the beater brush decreases.  
      Advantageously, the control member comprises a knob mounted to turn on the structure, said knob presenting two cam paths, each suitable for causing a respective switch to open or close, namely a first switch S 1  which, when in the closed position, powers both motors, and a second switch S 2  which, when in the closed position, short-circuits the second motor.  
      Another object of the invention is to provide a cordless two-motor vacuum cleaner in which the three-position control member also actuates the means for selectively putting the first duct or the coupling of the second duct into communication with the collector.  
      This other object is achieved according to the invention by the fact that the control member comprises a knob mounted to turn on the structure, said knob presenting the means for selectively putting the first duct or the coupling for the second duct into communication with the collector, and further presenting two cam paths each suitable for controlling the opening and the closing of a respective switch, namely a first switch which, when in the closed position, powers at least the first motor, and a second switch controlling the operation of the second motor.  
      Under such circumstances, the electrical circuit for powering the motors is made in such a manner that in the third position of the control member, both motors are powered in parallel, the second switch controlling a microprocessor which manages the power delivered by the two motors.  
      According to another advantageous characteristic of the invention, the knob further presents the means for selectively putting the first duct or the coupling for the second duct into communication with the collector.  
      Preferably, the knob comprises a cylindrical body having a bent channel formed therein opening out firstly in the rear face of said knob and secondly to one side of its periphery, said body being received in a cylindrical cavity formed in the structure, the bottom of said cavity including an orifice communicating with the collector, and the periphery of said cavity presenting two diametrically opposite orifices into which there open out respectively the first duct and the coupling for the flexible duct.  
      The following dispositions are preferably also adopted. The cam paths are formed at the periphery of the body and are disposed in parallel planes perpendicular to the axis of the knob.  
      The first cam path which controls opening and closing of the first switch (S 1 ) presents two diametrically opposite protuberances, and the second cam path which controls opening and closing of the second switch (S 2 ) presents only one protuberance.  
      The protuberance of the second cam path and the protuberances of the first cam path are disposed in a plane that contains the axis of rotation of the knob.  
      The two switches (S 1 , S 2 ) are in radially opposite regions of the cavity in which the knob is received.  
      The protuberances are disposed in the plane of symmetry of the bent channel. 
    
    
      Other advantages and characteristics of the invention appear on reading the following description made by way of example and with reference to the accompanying drawings, in which:  
       FIG. 1  is a profile view in section of a vacuum cleaner in accordance with the invention;  
       FIG. 2  shows the electrical circuit diagram of the prior art;  
       FIG. 3  shows the electrical circuit diagram of the invention;  
       FIG. 4  is a section on a plane of symmetry through the knob which allows changeover from beater mode to suction mode, and enables the motors received in a cavity of the frame to be stopped; and  
       FIG. 5  is a section on line V,V of  FIG. 4 . 
    
    
      The vacuum cleaner shown in  FIG. 1  comprises a structure  1  mounted on transport members R, and carrying a turbine T driven by a first electric motor M 1  and serving to create suction in a particle collector by acting through a filter membrane M. The turbine T and the first motor M 1  are received in a chamber k, and under such circumstances the collector is constituted by a flexible bag S having an air-permeable wall that is enclosed in a compartment K whose top and sides are defined by a leakproof rigid wall and whose bottom is defined by the membrane M that provides separation relative to the suction chamber k. The membrane M may form part of the bag S. The turbine T applies suction to the compartment K and evacuates the air it sucks in via a volute  11  which leads into a chamber  12  communicating with the outside through orifices.  
      At its bottom end, the structure  1  is provided with a beater brush B in the form of a rotary brush driven by a second motor M 2 .  
      Reference E designates a rechargeable battery housed in a case A disposed under the turbine T and serving to feed direct current to the two motors M 1  and M 2 .  
      The bag S is held inside the compartment K by means of projections D secured to the inside wall of said compartment K and it includes an opening  20  that fits on an outlet  21  of a device  30  enabling the inside of the bag S to be put selectively into communication either with a duct C connected to the beater brush B, or else with a coupling  40  suitable for coupling to one end of a flexible duct  41  which is fitted at its other end with a suction nozzle  42 .  
      Reference N designates a handle of the vacuum cleaner that is in the form of an upside-down U shape, and it may be slidably mounted on the structure.  
       FIG. 2  shows the electric power supply circuits for the two motors M 1  and M 2  in the prior art.  
      The two motors M 1  and M 2  are connected in parallel. A general first switch S 1  serves to feed electricity to the first motor M 1  for driving the turbine T, both in the beater mode of operation and in the suction mode of operation. A second switch S 2 , when in its closed position, serves to feed electricity to the second motor M 2  for driving the beater brush B, providing the first switch S 1  is also in its closed position.  
       FIG. 3  shows the electrical wiring of the vacuum cleaner  1  in a first aspect of the invention, as described in detail below.  
      The two motors M 1  and M 2  are connected in series and the first switch S 1 , when in the closed position, enables electricity to be fed to both motors M 1  and M 2 . The second switch S 2  is mounted in the circuit in such a manner that when in its closed position it shunts the motor M 2  for driving the beater brush B.  
      When the vacuum cleaner is used in beater mode, the first switch S 1  is in the closed position and the second switch S 2  is in the open position. The sum of the voltages across the motors M 1  and M 2  is thus equal to the voltage across the battery E.  
      When the vacuum cleaner is used in suction mode, the first switch S 1  is in the closed position and the second switch S 2  is also in the closed position. The second motor M 2  is then shunted or short-circuited. The voltage applied to the first motor M 1  is equal to the voltage of the battery E.  
      When the vacuum cleaner is at rest, the first switch S 1  is in the open position. The member for controlling the two switches S 1  and S 2  ensures that in the rest or stop position, the second switch S 2  is likewise in the open position.  
      Tables 1 and 2 below show examples of the voltages U applied to the motors M 1  and M 2 , together with the corresponding current I (amps), power P (watts), suction DP (mm of water), and turbine speed N (in revolutions per minute (rpm)), both when the bag S is clean (Table 1) and clogged (Table 2) for operation in beater mode.  
                                       TABLE 1                                   U (V)   I (A)   P (W)   DP (mm H 2 O)   N (rpm)                                                                    M1   6.0   9.0   54   150   10,000           M2   6.0   9.0   54           E   12.0   9.0   108                      
 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
               
               
                   
                 U (V) 
                 I (A) 
                 P (W) 
                 DP (mm H 2 O) 
                 N (rpm) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 M1 
                 8.0 
                 8.0 
                 64 
                 300 
                 14,000 
               
               
                   
                 M2 
                 4.0 
                 8.0 
                 32 
               
               
                   
                 E 
                 12.0 
                 8.0 
                 96 
               
               
                   
                   
               
            
           
         
       
     
      It can be seen that when the bag S is clogged, the voltage applied to the motor M 1  increases while the voltage applied to the motor M 2  decreases. Thus, the proposed wiring makes it possible automatically to increase the power of the first motor M 1  driving the turbine T as a function of the extent to which the bag S is filled.  
      Table 3 below shows the same values, but when operating in suction mode, when the motor M 1  is the only motor being powered electrically, both for a clean bag S and a clogged bag.  
                                       TABLE 3                                   U (V)   I (A)   P (W)   DP (mm H 2 O)   N (rpm)                                                                Clean bag   M1   12.0   20.0   240   250   15,000       Clogged   M1   12.0   10.0   120   550   19,000       bag                  
 
      It can be seen that in this mode of operation, the suction created by the turbine increases greatly when the bag is full.  
       FIGS. 4 and 5  show the device  30  that enables the inside of the bag S to be put selectively into communication either with the duct C or with the coupling  40  for the flexible duct  41 . This device  30  is in the form of a knob  31  mounted to turn about an axis of rotation  32  that is coaxial with the outlet  21  onto which the opening  20  of the bag S is mounted. The bottom  32  comprises a cylindrical body  33  of axis  32  which is received in a cylindrical cavity  34  formed in the structure  1 . The coupling  35  for the duct C and the coupling  40  for the flexible duct  41  of the suction device  42  open out into the cylindrical cavity  34  in opposite directions perpendicular to the axis X. The cylindrical body  33  has a bent channel  36  with one end opening out into the outlet  21  and with its other end opening out to the periphery of the cylindrical body  33  and capable of being put into register with one or other of the couplings  35  and  40  by turning the knob  31  about the axis  32 .  
      On its outside face, the knob  31  also presents handle means  37  in the form of a lug for enabling said knob  31  to be turned manually about the axis  32 .  
      Close to its inside end pressing against the bottom of the cavity  34 , the cylindrical body  33  presents a zone  38  of diameter that is smaller than that of the other portion of the body  33 , and that presents at its periphery two cam paths  39   a  and  39   b  lying in parallel planes perpendicular to the axis  32 , with the first path  39   a  serving to control the first switch S 1 , and the second path  39   b  serving to control the second switch S 2 , these two switches S 1  and S 2  being mounted in housings provided at the periphery of the cylindrical cavity  34  and being substantially diametrically opposite.  
      The first cam path  39   a  is formed by the cylindrical periphery of the zone  38  and by two protuberances  44  and  45  that are diametrically opposite, while the second cam path  39   b  is formed by the cylindrical periphery of the zone  38  and by a single protuberance  46  disposed in the immediate vicinity of the protuberance  45 . The protuberances  44 ,  45 , and  46  are preferably situated in the plane of symmetry of the knob  31  that contains the mid-line of the bent channel  36 .  
      In the position of the knob  31  that is shown in  FIGS. 4 and 5 , the switch S 1  is closed, the switch S 2  is closed, and the flexible duct  41  is in communication with the inside of the bag S via the coupling  40 , the bent channel  36 , and the outlet  21 . In this configuration, the first motor M 1  is fed with electricity, the second motor M 2  is shunted, and the vacuum cleaner operates in suction mode.  
      If the knob  31  is turned through 180°, in either direction about the axis  32 , the switch S 1  is closed, the switch S 2  is open, and the duct C is in communication with the inside of the bag S via the coupling  35 , the bent channel  36 , and the outlet  21 . The two motors M 1  and M 2  are thus connected in series and powered by the battery E. The vacuum cleaner then operates in beater mode.  
      When on turning the knob  31  about the axis  32 , the protuberances  44 ,  45 , and  46  move away from the vertical position, both switches S 1  and S 2  open and the motors M 1  and M 2  stop since they are no longer fed with electricity. The vacuum cleaner is then in stop or rest mode.  
      It should be observed that the knob  31  can easily be withdrawn from its housing, thereby necessarily opening the switches S 1  and S 2  and stopping the motors M 1  and M 2 . This disposition makes it easy to clean the bent channel  36  in the event of it becoming jammed.  
      When both motors M 1  and M 2  are powered in parallel, as shown in  FIG. 2 , the device  30  enabling the inside of the bag S to be put selectively into communication either with the duct C or with the coupling  40  for the flexible duct  41  is identical to that shown in  FIGS. 4 and 5  and described above.  
      The switch S 1  in the closed position then causes electricity to be fed to an electronic power circuit including a microprocessor that manages the amount of electrical power delivered to the motors M 1  and M 2  as a function of whether the switch S 2  is open or closed.