Abstract:
A vacuum cleaner canister includes a mechanism cooperable with the canister inlet duct to divide the canister into an upper zone of high velocity vortex air flow and a lower zone of reduced velocity air flow so as to reduce the likelihood of recycling particles through the vacuum cleaner filters. The inlet duct is positioned below the filters. The duct redirects air flow downwardly from the inlet port into the canister and a baffle redirects the downward flow to a circumferential flow.

Description:
This application is a continuation of application Ser. No. 10/623,356, filed Jul. 18, 2003. 
    
    
     BACKGROUND OF THE INVENTION: 
     This invention relates generally to vacuum cleaning equipment and more particularly concerns a vacuum cleaner having filters backflushed with ambient air. 
     Cleaning filtered vacuums is presently accomplished by shaker, percussion, forced air or compressed air systems. Such systems periodically apply mechanical or pneumatic forces to dislodge particles collected on the intake surfaces of the filters. To accomplish this, a force system other than the primary vacuum system is required, such as a second blower motor, a compressor or a shaker or percussion system motor. These added components make backflushed vacuums considerably more expensive and more readily subject to malfunction. 
     Except for very expensive complex 240 volt systems, these systems are mechanically controlled. Therefore, they have limited flexibility in their operating parameters. While their cycle time can be varied, perhaps by changing the rotational speed of a cam, the fractional relationship of the backflush time to full cycle time can only be changed by an exchange of mechanical components, such as the cam drive motor. The efficiency of the backflush cycle, however, is dependent on the proper coordination of the cycle and backflush times to the characteristics of the particular medium being vacuumed. For example, a short burst of backflushed air will clean dust collected on a filter, but a longer burst is necessary to dislodge particles of plastic or fibers. 
     These problems are exacerbated because these systems generally exhibit considerable turbulence within the collecting canister, and as a result the same particles are often continuously recycled, unnecessarily overloading the backflush system. 
     It is, therefore, an object of this invention to provide a backflushed filter vacuum which uses ambient air to backflush the filters. Another object of this invention is to provide a backflushed filter vacuum which does not require use of a secondary shaker, percussion, forced air or compressed air system. A further object of this invention is to provide a backflushed filter vacuum which can be controlled by an electronic system economically compatible with a relatively inexpensive 120 volt machine. Yet another object of this invention is to provide a backflushed filter vacuum which permits independent control of both cycle and backflush time. It is also an object of this invention to provide a backflushed filter vacuum which permits cycle and backflush times to be varied relative to each other without interchanging mechanical components. Still another object of this invention is to provide a backflushed filter vacuum which permits the user to adjust cycle and backflush times to suit the medium being vacuumed. An additional object of this invention is to provide a backflushed filter vacuum which reduces the likelihood of recycling particles through the filters. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a vacuum cleaning machine has a canister with an inlet port and at least two outlet ports. At least two filters are disposed inside of the canister, one in pneumatic communication through a corresponding one of each of the outlet ports. At least two valves are disposed outside of the canister. Each valve is in pneumatic communication between a vacuum source and a corresponding outlet port so as to permit air to be drawn by the vacuum source from the inlet port simultaneously through the filters. A controller operates the valves to switch the filters from connection to the vacuum source to connection to ambient air so as to permit ambient air to be sequentially intermittently drawn through corresponding valves and filters into the canister. Preferably, the controller includes a timing mechanism for setting the delay time between cycles of the sequential valve operation and a timing mechanism for setting the intermittent time of connection of each filter to ambient air. 
     The preferred valve has a housing with a continuously opened port and two reciprocally opened and closed ports. A piston disposed between the two ports is biased to a first position in which one of the two ports is closed and the other of the two ports is opened. A mechanism for overcoming the bias moves the piston to a second position in which the closed port is opened and the opened port is closed. The preferred bias overcoming mechanism is a solenoid with a switch. The continuously opened port is in pneumatic communication with the filter. One of the two reciprocal ports is in pneumatic communication with the vacuum source and the other with ambient air. When the solenoid is energized, the valve connects its filter to ambient air. When the solenoid is de-energized, the valve connects its filter to the vacuum source. 
     In a specially preferred embodiment, the vacuum cleaning machine has a canister with an opening in its top and an inlet port. A plate closes the opening. The plate has three outlet ports. Three filters are mounted on the plate and disposed inside of the canister one in pneumatic communication through a corresponding one of each of the outlet ports. A vacuum source and three valves are also mounted on the plate outside of the canister. Each valve has a first port in continuously opened pneumatic communication with a corresponding outlet port, a second port in pneumatic communication with the vacuum source and a third port in pneumatic communication with a source of ambient air. A piston reciprocally disposed between the second and third ports is biased by a coil spring to simultaneously close the third port and open the second port in a vacuum mode. A solenoid overcoming the bias reciprocates the piston to simultaneously close the second port and open the third port in a backflush mode. The controller causes the valves to sequentially switch the filters from communication with the vacuum source to communication with ambient air for a preset time. The controller is preferably configured to allow the operator to set the cycle time of the sequential valve operation and also to set the intermittent time of connection of the filters to ambient air. 
     Preferably, the canister also contains a mechanism cooperable with the inlet port to divide the canister into an upper zone of high velocity vortex air flow and a lower zone of reduced velocity air flow so as to reduce the likelihood of recycling particles through the filters. This can be achieved by positioning the inlet port below the filters and above the bottom of the canister using a duct to redirect air flow downwardly in the canister from the inlet port and using a baffle to redirect the downward flow to a circumferential flow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a block diagram of the ambient air backflushed filter vacuum; 
         FIG. 2  is a side elevation of the ambient air backflushed filter vacuum; 
         FIG. 3  is a top plan view of the backflushed filter vacuum pneumatics; 
         FIG. 4  is a top plan view of a typical valve of the backflushed filter vacuum; 
         FIG. 5  is a side elevation view of the valve of  FIG. 4 ; 
         FIG. 6  is a plan view of an electromechanical control system for the backflushed filter vacuum valves; 
         FIG. 7  is a schematic electrical diagram of the electromechanical system of  FIG. 6 ; 
         FIG. 8  is a block diagram of an electronic control system for the backflushed filter vacuum valves; and 
         FIG. 9  is a schematic diagram of the electronic control system of  FIG. 8 . 
     
    
    
     While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Turning first to  FIG. 1 , the ambient air backflushed filter vacuum generally includes a canister  10  with three, outlet ports  11 ,  12  and  13  and an inlet port  14 . Three filters  21 ,  22  and  23  are disposed within the canister  10  and three valves  31 ,  32  and  33  are disposed outside of the canister  10 . Each of the valves  31 ,  32  and  33  has a continuously opened port  31   c ,  32   c  or  33   c  which is in constant communication through a respective outlet port  11 ,  12  or  13  with a respective filter  21 ,  22  or  23 . Each valve  31 ,  32  and  33  also has two reciprocally opened and closed ports  31   a  and  31   b ,  32   a  and  32   b  and  33   a  and  33   b , respectively, and an operating mechanism  31   d ,  32   d  and  33   d , respectively, for switching the valves  31 ,  32  and  33  between their reciprocal ports “a” and “b”. One reciprocal port “a” of each of the valves  31 ,  32  and  33  is connected to a vacuum source  15  and the other reciprocal port “b” of each of the valves  31 ,  32  and  33  is in pneumatic communication with a source of ambient air  16 . A controller  17  causes the operating mechanisms  31   d ,  32   d  and  33   d  to sequentially operate to switch the filters  21 ,  22  and  23  from pneumatic communication with the vacuum source  15  to pneumatic communication with ambient air  16 . Each of the valves  31 ,  32  and  33  is normally connected so that the vacuum source  15  draws ambient air  16  through the canister inlet port  14  into the canister  10  and through the walls of the filters  21 ,  22  and  23 . The controller  17  then sequentially causes the valves  31 ,  32  and  33  to switch to the ambient air port “b”. When, for example, one valve  31  is in this backflushed mode through its ambient air port “b”, the other valves  32  and  33  continue in the vacuum mode through their respective vacuum ports “a”. The suction through the filters  22  and  23  draws ambient air  16  through the valve port  31  “b” and into the filter  21 , reversing the flow of air through the filter  21  and causing particles that have collected on the outer wall of filter  21  to be dislodged to drop to the bottom of the canister  10 . After a brief, predetermined backflush time, the controller  17  will cause the first valve  31  to return to its vacuum port “a” so as to resume the vacuum mode through all three filters  21 ,  22  and  23 . After another predetermined time lapse, the controller  17  will sequentially perform the same operation on a second valve  32 , so that the other valves  31  and  33  cause the second filter  22  to be backflushed. When the second filter  22  has been backflushed for the predetermined time period and the delay time has elapsed, the controller  17  will then cause the same operation to occur with respect to the third filter  23 . The cycle continues for as long as the vacuum source  15  is in operation. When the third filter  23  has been backflushed, the controller  17  will delay for a predetermined time period before reinitiating the cycle. Preferably, and as hereinafter explained, the controller  17  is configured so as to allow the user to select both the delay time and the backflush time for the system. 
     Turning now to  FIG. 2 , the structural configuration of the canister  10  is illustrated. The canister  10  is a cylindrical container having side walls  18 , a bottom  24  and an open top. The open top is covered by a circular plate  19 . The filters  21 ,  22  and  23  are mounted to the bottom of the plate  19  and pneumatically communicate through the outlet ports  11 ,  12  and  13  in the plate  19 . The inlet port  14  to the canister  10  extends through its side wall  18 , as shown at a point below the bottom of the filters  21 ,  22  and  23  and above the bottom  24  of the canister. The valves  31 ,  32  and  33 , the operating mechanisms  31   d ,  32   d  and  33   d , the controller  17  and the vacuum source  15  are mounted above the plate  19  and are protected by a cover  25  which is seated on the plate  19 . An opening  26  is provided in the cover  25  to exhaust air discharged from the vacuum source  15 . A handle  27  is provided proximate the bottom of the canister  10  to facilitate lifting and handling of the unit. Casters  28  at the bottom  24  of the canister  10  allow the canister  10  to be freely rolled in any direction. Latches  29  permit removal of the cover  25  and the plate  19  from the canister  10  to allow access to the interior of the canister  10  and the filters  21 ,  22  and  23 . 
     Continuing to look at  FIG. 2 , an assembly for maximizing the efficiency of airflow within the canister  10  during use is also seen. A duct  41  is provided inside the canister  10  to redirect air flow through the inlet port  14  downwardly and proximate the side wall  18  of the canister  10 . The inlet port  14  can be above the bottom level of the filters  21 ,  22  and  23  as long as the duct  41  extends below the filters  21 ,  22  and  23 . A baffle  42  is positioned within the canister  10  slightly below the outlet end of the duct  41 . The baffle  42  is sized to provide a barrier to the path of air flow from the duct  41 . As shown, the baffle  42  is secured to the canister wall  18  by an external bolt  43  which can be loosened to permit changing the angle of inclination of the baffle  42  from horizontal. The baffle  42  redirects the air flow into a circular vortex above the baffle  42 . Below the baffle  42 , air flow velocities are considerably reduced and there is little turbulence. As a result, when particles filtered by the filters  21 ,  22  and  23  are backflushed from the filters  21 ,  22  and  23 , the particles settle to the bottom  24  of the canister  10  and are far less likely to be recycled through the filters  21 ,  22  and  23 . It has been found that a baffle angle of 10 degrees from horizontal works effectively, though this angle may be varied considerably. 
     Turning now to  FIG. 3 , a preferred embodiment of the valves  31 ,  32  and  33  and their operating mechanisms is illustrated. A central housing  44  is preferably concentrically located on top of the circular plate  19  covering the canister  10 . The central housing  44  may be fixed to the plate  19  by screws  45  and a plate  46  covering the central housing  44  is also fastened to the housing  44  by screws  47 . A concentric motor mount spacer  48  is fastened to the top of the central housing cover plate  46  and extends upwardly to and supports the mount  49  for the vacuum source  15 . The valves  31 ,  32  and  33  are concentrically disposed about the central housing  44 , preferably displaced at equal angles. Thus, as shown, for the three valve configuration, the valves  31 ,  32  and  33  are at 120 degree intervals about the center of the central housing  44 . 
     The configuration of each of the valves  31 ,  32  and  33  is shown in  FIGS. 4 and 5  and is explained in relation to one of the valves  31 . The other valves  32  and  33  are in all respects identical to the valve  31  now described. A mounting plate  51  is fixed to the canister plate  19  at an elevation determined by standoffs  52 . The valve  31  is formed by a cylindrical housing  34  also fastened to the canister plate  19  by screws. The central housing  44  is connected to the valve housing  34  by a radial duct  35 . The ambient air port  31   b  is radially aligned with the duct  35  which forms the vacuum port  31   a  for the valve  31 . The ambient air duct  36  extends from the ambient air port  31   b  into the source of ambient air  16 . The valve housing  34  is completed by a cover  37  fastened to the top of the housing  34  by screws  38 . 
     The operating mechanism  31   d  for the valve  31 , shown generally in  FIG. 1 , is also shown in greater detail in  FIGS. 4 and 5 . A solenoid  61  is mounted on the plate  51  with the solenoid shaft  62  aligned on the radius extending through the central axis of the ducts  35  and  36 . The remainder of the operating mechanism  31   d  is best understood in relation to the manner in which it is assembled. The solenoid shaft  62  has a threaded portion on which is threaded a bolt  63 . A gasket  64  and a valve plate  65  slide over the shaft  62  with the plate  65  against the bolt  63  and the bolt  63  seated in a hole in the gasket  64 . The gasket  64  and plate  65  are configured to cover the vacuum port  31   a  of the valve  31 . A sleeve  66  slides over the shaft  62  against the valve plate  65 . An integral bushing  67  and bracket  68  slide over the sleeve  66  and a spring  69  slides over the sleeve  66  and against the bushing  67 . A second valve plate  71  and gasket  72  slide onto the shaft  62  and against the sleeve  66 . A nut  73  is tightened onto the threaded end of the shaft  62  and seats in a hole in the gasket  72  against the second plate  71 . The second valve plate  71  and gasket  72  are configured so as to cover the ambient air port  31   b  of the valve  31 . The valve plates  65  and  71  taken together form a piston of a length determined by the length of the sleeve  66 . The bracket  68  is fastened to the valve cover  37  by screws  74 . The travel of the piston is therefore determined by the spacing of the vacuum port  31   a  and the ambient air port  31   b . The solenoid  61  and the spring  69  are coordinated so the spring  69  exerts 2.3 psi against the second valve plate  71  in its preloaded condition and can be fully compressed at 4 psi. The spring  69  normally holds the ambient air port  31   b  closed and the vacuum air port  31   a  opened. When the solenoid  61  is energized, its pull overcomes the spring  69  to shift the piston to close the vacuum port  31   a  and open the ambient air port  31   b  of the valve  31 . 
     As seen in  FIG. 4 , additional solenoids can be mounted at 120 degree intervals on the solenoid mounting plate  51  to serve the remaining valves illustrated in  FIG. 3 . Coordinated selection of the solenoid  61 , the spring  69 , the diameter of the valve housing  34  and the length of the piston defined by the valve plates  65  and  71  and the sleeve  66  in the above described assembly procedure automatically establishes the piston travel distances and preloads the appropriate spring compression. Upon energizing the solenoid  61 , the bias of the spring  69  is overcome and the solenoid  61  quickly pulls the piston to close the vacuum port  31   a  and open the ambient air port  31   b  of the valve  31 . A central opening  54  in the cover plate  46  in the central housing  44  allows pneumatic communication through the cylindrical spacer  48  to the vacuum source  15 . All of the housing and duct components are sealed at their connections to assure the pneumatic integrity of the system. 
     Turning now to  FIGS. 6 and 7 , an electro-mechanical embodiment of the controller  17  is illustrated. In this embodiment solenoids  61 ,  62  and  63  are controlled by switches  81 ,  82  and  83 , respectively, which are operated by a cam  84  driven by a geared cam motor  85  connected to the cam  84  by a drive shaft  86 . The cycle time for operation of the switches  81 ,  82  and  83  by the cam  84  is not adjustable without a change of structural components, such as selection of a motor with a different rpm. The components of the controller  17  are connected as illustrated through a terminal block  88 . The vacuum source  15  and main power on/off switch  89  are also connected via the terminal block  88 . The vacuum motor  15  is grounded  91  and the cam motor  85  is provided with a capacitor  92  to assist in operation of the motor  85 . When the machine main power switch  89  is turned on, the vacuum motor  15  and cam motor  85  are both energized. As long as the switches  81 ,  82  and  83  remain open, the solenoids  61 ,  62  and  63  remain de-energized and all of the filters  21 ,  22  and  23  are connected to the vacuum source  15  through the valve vacuum ports  31 a,  32 a and  33 a. As the cam  84  rotates to engage the next of the switches  81 ,  82  or  83  in its path, the solenoids  61 ,  62  and  63  are sequentially energized to close their respective vacuum ports  31   a ,  32   a  and  33   a  and to open their ambient air ports  31   b ,  32   b  or  33   b , respectively, so as to connect their respective filters  21 ,  22  or  23  to ambient air  16 . The filter  21 ,  22  or  23  will be backflushed for as long as their associated solenoids  61 ,  62  or  63  remain energized, a period determined by the relation of the cam  64  to the contact elements of the switches  81 ,  82  or  83 . As shown in  FIG. 6 , the controller  17  and its components are mounted on the canister plate  19 . 
     Turning now to  FIGS. 8 and 9 , an electronic embodiment of the controller  17  is illustrated. In this embodiment, when the system main power switch is turned on, the controller power switch  101  is also turned on. The controller consists essentially of two timers  102  and  103 . The first timer  102  establishes the delay time between activation of the solenoids  61 ,  62  and  63 . The second timer  103  establishes the “on” time for each of the solenoids  61 ,  62  and  63  and an “off” time before the next solenoid  61 ,  62  or  63  is energized. The use of this embodiment has the added advantage of allowing the user by means of the first timer  102  to select the delay time between sequential operations of the solenoids  61 ,  62  and  63 . The user is also permitted through the second timer  103  to select the “on” time, as shown from 0.5 to 5.0 seconds, for each of the solenoids  61 ,  62  and  63  so that each filter  21 ,  22  and  23  will receive one burst of backflushing ambient air for the selected backflush time interval. The time between solenoid operations is also set by the backflush timer  103  and may be, but as shown is not, variable by the user. As shown, an “off” time of 5 seconds is selected. This can be set at any value by the manufacturer. Assuming for example, an “off” time of 0.5 seconds, the delay timer  102  being set for 3 minutes and the backflush timer  103  being set for 10 seconds, the total cycle time will be 3 minutes 45 seconds. That is, every 3 minutes and 45 seconds, each filter  21 ,  22  and  23  will be backflushed once. 
     As seen in  FIG. 9 , when power is applied, the delay timer  102  starts. The delay time can be set from 1.5 to 5 minutes by the operator with a screw driver adjusted potentiometer  131  or some other type device. When the delay timer  102  times out, it starts the backflush timer  103 . The second timer  103  operates the control relays  121 ,  122  and  123  which actuate the switches  81 ,  82  and  83  to pick up the solenoids  61 ,  62  and  63 . Each solenoid  61 ,  62  and  63  is energized sequentially during the cycle. The duration “on” time for each solenoid  61 ,  62  and  63  is adjustable from 0.5 seconds to 5 seconds with an operator controlled screw driver adjusted potentiometer  132  or some other device. Duration “on” time is the same for all solenoids  61 ,  62  and  63  once set. At the end of the cycle, the delay timer  102  is reinitiated. This cycling continues until power is turned off. Preferably, the delay timer  102  employs a single dual pressure monostable multi-vibrator  104  with a variable resistor  131  to permit delay time adjustment by the user. An LED  106  is provided as confirmation of operation of the delay timer  102 . The backflush timer  103  employs three such multi-vibrator chips  107 ,  108  and  109  in a cascaded configuration with LED&#39;s  111 ,  112  and  113  and  114 ,  115  and  116 , respectively, to indicate the ON/OFF condition of each of the control relays  121 ,  122  and  123  which, in turn, pick up the switches  81 ,  82  and  83  for their respective solenoids  61 ,  62  and  63 . 
     A prototype of the ambient air backflushed filter vacuum was satisfactorily tested with the following components: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Element 
                 Component 
                 Description 
               
               
                   
               
             
             
               
                 10 
                 canister 
                 18¼″ I.D. × 22″ H 16 gauge carbonate steel 
               
               
                 15 
                 vacuum 
                 2-stage 110 volt AC 115 cfm vacuum motor 
               
               
                   
                 source 
                   
               
               
                 19 
                 plate 
                 19¼″ diameter 10-gauge galvanized cold 
               
               
                   
                   
                 rolled sheet metal 
               
               
                 21, 22, 23 
                 filters 
                 99.8% at 0.2 micron cartridge filters 
               
               
                 25 
                 cover 
                 20″ diameter × 11″ H ABS plastic 
               
               
                 34 
                 valve 
                 3″ diameter schedule 40 PVC plastic 
               
               
                   
                 housings 
                   
               
               
                 35 
                 ducts 
                 2″ diameter schedule 40 PVC plastic 
               
               
                 36 
                 ducts 
                 1½″ diameter schedule 40 PVC plastic 
               
               
                 44 
                 central 
                 6″ diameter schedule 40 PVC plastic 
               
               
                   
                 housing 
                   
               
               
                 48 
                 spacer 
                 4″ diameter schedule 40 PVC plastic 
               
               
                 61, 62, 63 
                 solenoids 
                 110 volt AC/pull rate of 4# at 0.5″ stroke 
               
               
                 64 
                 gaskets 
                 closed cell PVC foam 
               
               
                 65 
                 valve 
                 16 gauge cold rolled sheet metal 
               
               
                   
                 plates 
                   
               
               
                 66 
                 sleeves 
                 ¼″ diameter × 1¼″ aluminum spacers 
               
               
                 67/68 
                 bushing/ 
                 HMHD polypropylene/high impact plastic 
               
               
                   
                 bracket 
                   
               
               
                 69 
                 spring 
                 conical compression spring/1¾″ compressed 
               
               
                   
                   
                 to ¾″ at 2.3 psi and fully compressed at 4 psi 
               
               
                 85 
                 cam motor 
                 4 rpm geared AC motor 
               
               
                 104 
                 multi- 
                 555/4541 
               
               
                   
                 vibrator 
                   
               
               
                 107, 108, 
                 multi- 
                 4538 
               
               
                 109 
                 vibrator 
               
               
                   
               
             
          
         
       
     
     While the machine has been described in relation to a three filter system, the machine could employ any number of filters and associated valve, solenoid and switch combinations provided that at least two such combinations are employed so that at least one combination will always provide suction from the vacuum source  15 . The valves  31 ,  32  and  33  may employ hinged covers or other mechanisms than pistons. The valve operating mechanisms  31   d ,  32   d  and  33   d  may be structurally different as long as the vacuum ports “a” and ambient air ports “b” are closed at pressures not defeated by the suction of the vacuum source  15  but within the bias overcoming force of the solenoids  61 ,  62  and  63 . 
     Thus, it is apparent that there has been provided, in accordance with the invention, an ambient air backflushed filter vacuum that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.