Abstract:
A battery operated spray pump includes a piston pump having a double wave cam which is pushed by a pair of rotating cam pushers coupled to the electric motor via a gear transmission. The double wave cam has an unequal duty cycle, i.e. takes more time to expel fluid from the piston cylinder than it takes to fill the cylinder. The cam pushers rotate at a speed which, in conjunction with the duty cycle of the cam, produces a low pressure nearly constant stream.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates broadly to battery operated fluid pumps. More particularly, this invention relates to a battery operated fluid pump contained in a spray head which fits onto existing pump spray containers and which exhibits substantially continuous spray.  
         [0003]     2. State of the Art  
         [0004]     Many household and industrial products are sold in containers that include a sprayer. These products include cleansers, insecticides, polishes, waxes, etc. There are several kinds of sprayers used with these products. Perhaps the most common is the manual push button or trigger operated pump which is seen most frequently on liquid cleansers. It has the advantage of being environmentally friendly (i.e. it does not require a propellant) but the disadvantage of delivering fluid in a series of pulses rather than in a continuous spray. Another well known sprayer is the aerosol can which is sealed and charged with a gas propellant. This sprayer has the advantage that it dispenses fluid in a continuous spray, but has several disadvantages. One disadvantage is that the can cannot be refilled. Another disadvantage is that depending on the gas used to charge the container, the propellant can be environmentally unfriendly. While environmentally friendly propellants do exist, generally, they do not charge as well as the unfriendly gases. Still another popular sprayer is the air pump sprayer seen most frequently with insecticides and liquid garden products. The pump sprayer includes a hand operated air pump which is used to charge the container with compressed air. After it is charged, it operates much like an aerosol can. The pump sprayer is environmentally friendly but requires considerable effort to keep charged because air is not as efficient a propellant as environmentally unfriendly gases such as FREON or hydrocarbon gasses.  
         [0005]     In recent years there has been some experimentation with battery powered pump sprayers. Most of these devices include a spray mechanism which is similar to the ubiquitous push button (or trigger) pump sprayer but which is coupled to a battery powered electric motor by some type of linkage which converts the rotary action of the motor into an oscillatory motion to drive the pump piston. Many of these battery operated pump sprayers are designed to work only with a specially constructed bottle, i.e. they are not retrofittable to existing pump spray bottles. Many also have weight distribution problems, i.e. they are top heavy and cause the bottle to which they are attached to tip over. Many of these battery powered pumps have large priming volumes, thus causing a delay between the time the pump is activated and the time liquid begins to be dispensed. Significantly, these pumps do not really provide a constant spray. They provide a continuous pulsed spray like that obtained by repeatedly squeezing the trigger of pushing the button on a hand operated spray pump.  
       SUMMARY OF THE INVENTION  
       [0006]     It is therefore an object of the invention to provide a battery operated spray pump.  
         [0007]     It is another object of the invention to provide a battery operated spray pump that is retrofittable to an existing spray bottle.  
         [0008]     It is an additional object of the invention to provide a battery operated spray pump which produces a substantially continuous spray rather than a pulsed spray.  
         [0009]     In accord with these objects, which will be discussed in detail below, a battery operated spray pump according to the invention includes a piston pump having a double wave cam which is pushed by a pair of rotating cam pushers coupled to the electric motor via a gear transmission. The double wave cam has an unequal duty cycle, i.e. it uses more time to expel fluid from the piston cylinder than it uses in filling the cylinder. The cam pushers rotate at a speed which, in conjunction with the duty cycle of the cam, produces a low pressure relatively constant stream. According to the presently preferred embodiment, the duty cycle of the cam is approximately 270° and the speed of the cam pushers is approximately three rotations per second.  
         [0010]     Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a partially transparent side elevation view of a sprayer according to the invention;  
         [0012]      FIG. 2  is a partially disassembled perspective view of the sprayer of  FIG. 1 ;  
         [0013]      FIG. 3  is a further disassembled perspective view of the sprayer of  FIGS. 1 and 2 ;  
         [0014]      FIG. 4  is an exploded perspective view of the motor drive components;  
         [0015]      FIG. 5  is an enlarged side elevation view of the double wave cam;  
         [0016]      FIG. 6  is an enlarged top plan view of the double wave cam;  
         [0017]      FIG. 7  is an enlarged side elevation view of the cam pusher;  
         [0018]      FIG. 8  is an enlarged top plan view of the cam pusher;  
         [0019]      FIG. 9  is an exploded perspective view of the piston pump components; and  
         [0020]      FIG. 10  is a view similar to  FIG. 5  but of a presently preferred double wave cam. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     Turning now to  FIGS. 1-3 , a battery operated spray head  10  according to the invention includes an ergonomic housing  12  coupled to a threaded bottle coupling  14  and including an adjustable nozzle  16  and a trigger  18 . The rear of the housing  12  includes a battery compartment  20  and extends rearward a sufficient amount to rest comfortably on the hand of the user when the user squeezes the trigger. Inside the housing  12 , there are several subsystems, including the power source (batteries)  22 , an electric motor  24 , a transmission  26 , and a piston pump  28 . The trigger  18  is arranged so that when it is squeezed, it operates a double valve  30  and an electrical switch  32 . One part of the double valve  30  fluidly couples the pump  28  to a tube (not shown) which extends from the valve  30  into the bottle  1  to which the bottle coupling  14  is attached. The other part of the double valve, opens an air path from the atmosphere to the interior of the bottle  1  via a tube  34  which extends from an opening (not shown) in the housing  12  to the valve  30 . The double valve  30  and the electrical switch  32  are described in co-owned U.S. Pat. No. 6,752,330 to DiMaggio et al., the complete disclosure of which is hereby incorporated by reference herein.  
         [0022]      FIG. 4  illustrates parts of the motor drive and transmission subsystems. These pieces include a front mounting bracket  40 , a rear mounting bracket  42 , a pinion gear  44 , a reduction gear  46  with associated axle  48 , a cam pusher drive gear  50  with associated axle  52  and rear spacer  54 , and a double wave cam  56 .  
         [0023]     The motor  24  is coupled to the front mounting bracket  40  with its-drive shaft  24 a extending rearward (see  FIG. 3  as well). The pinion gear  44  is coupled to the motor drive shaft  24   a . The reduction gear  46  is mounted between the front bracket  40  and the rear bracket  42  on its axle  48 . The large diameter portion  46   a  of the reduction gear  46  engages the pinion gear  44 . The small diameter portion  46   b  of the reduction gear  46  is engaged by the pusher drive gear  50 . More particularly, the pusher drive gear  50  is mounted between the reduction gear  46  and the rear bracket  42  on the axle  52  which engages both the spacer  54  and the double wave cam  56  which is mounted in the front bracket  40 . Before proceeding with the operation of the motor drive and transmission subsystems, it is advantageous to first consider details of the pusher drive gear  50  and the double wave cam  56 .  
         [0024]     Turning now to  FIGS. 5 and 6 , the double wave cam  56  includes an inner cylinder  56   a  and an outer cylinder  56   b , each being formed to present a cam surface  56   c ,  56   d , respectively, at one end thereof. The cam surfaces  56   c ,  56   d  are preferably identical in cam action (though having different diameters) and are offset from each other by 180 degrees. At the other end of the double wave cam  56 , a reduced diameter cylinder  56   e  extends axially therefrom and a pair of arms  56   f ,  56   g  extend radially outward.  
         [0025]     The cammed end of the double wave cam  56  is designed to interact with the pusher drive gear  50  which is illustrated in detail in  FIGS. 7 and 8 . The pusher drive gear  50  is generally disk shaped having a central mounting hole  50   a  and an outer plurality of gear teeth  50   b  arranged along its perimeter. A pair of cam pusher surfaces  50   c ,  50   d  are arranged on one side of the drive gear  50 . These surfaces follow a circular path having the same center as the gear  50  but have unequal radii. The radii are chosen to match the diameters of the inner and outer cylinders  56   a ,  56   b  of the double wave cam  56 . As illustrated, the pusher surface  50   c  is dimensioned to interact with the cam surface  56   c  of the inner cylinder  56   a  of the double wave cam  56 . The pusher surface  50   d  is dimensioned to interact with the cam surface  56   d  of the outer cylinder  56   b  of the double wave cam  56 .  
         [0026]     Turning now to  FIG. 9 , the piston pump assembly  28  includes a generally T-shaped valve body  60  having three openings  60   a - 60   c . Piston components  62 - 68  are fitted into the back opening  60   a  of the valve body  60 . Inlet ball valve components and tube connector  70 - 78  are fitted in the bottom opening  60   b  of the valve body  60 . Spray nozzle components  80 - 84  and  16  are fitted to the front opening  60   c  of the valve body  60 .  
         [0027]     The piston components include a spring  62 , a piston  64 , a piston rod  66 , and a retainer cap  68 . The spring  62  is inserted into the rear opening  60   a  of the valve body  60  and abuts an interior annulus (not shown). The piston  64  is inserted into the valve body  60  behind the spring which biases the piston backwards. The piston rod  66  is inserted behind the piston  64  and the retainer cap  68  is attached by force fitting to the valve body  60 . The retainer cap  68  has a central opening through which the piston rod  66  extends. The piston, piston rod, and the interior of the valve body wherein the piston moves are preferably coated with a silicone lubricant (not shown).  
         [0028]     The inlet ball valve components include a ball cage  70  having interior vanes (not shown), a valve ball  72 , a retainer tube  74 , a tube connector  76 , and an inlet elbow  78 . The retainer tube  74 , adapter tube  76 , and inlet elbow  78  are coupled to each other by epoxy and the retainer tube  74  is force fit into the bottom opening  60   b  of the valve body  60  capturing the ball  72  and the ball cage  70 . It will be appreciated however that some or all of the retainer tube  74 , adapter tube  76 , and inlet elbow  78  may be integrally formed.  
         [0029]     The spray nozzle components include a discharge valve  80 , a volume reducer  82 , spin mechanics  84 , and an adjustable nozzle  16 . The discharge valve is a circular flapper valve having a post  80   a  which extends forward into the volume reducer  82 . The volume reducer occupies a cylindrical space having a diameter smaller than the diameter of the valve  80 . The volume reducer  82  has a forwardly extending post  82   a  upon which the spin mechanics  84  is mounted. All of those components are inserted into the forward end  60   c  of the valve body  60  and the nozzle  16  is snap fit over the forward end of the valve body  60  where it retains the other components but is free to rotate.  
         [0030]     Referring back to  FIGS. 1-4 , and  9 , it will be appreciated that the transmission assembly  26  is mounted behind the piston pump assembly  28  with the double wave cam  56  mounted in the front bracket  40  by the arms  56   f ,  56   g  engaging slots  40   a ,  40   b  in the forward extending arms  40   c ,  40   d  of the bracket  40 . The cam  56  is arranged so that its cam surfaces  56   c ,  56   d  face and engage the pusher surfaces  50   c ,  50   d  of the gear  50 . The pump assembly  28  is mounted between the arms  40   c ,  40   d  of the bracket  40  with the piston rod  66  abutting the cylinder  56   e  of the double cam  56 .  
         [0031]     From the foregoing, those skilled in the art will appreciate that rotation of the motor drive shaft  24   a  causes rotation of the pinion gear  44  which rotates the reduction gear  48  at a slower rate. The reduction gear  48  causes rotation of the drive gear  50 . As the drive gear  50  rotates, the pusher surfaces  50   c ,  50   d  engage the cam surfaces  56   c ,  56   d  and cause the double wave cam  56  to reciprocate back and forth against the piston rod  66 . This causes the piston  64  to move back and forth in the valve body  60 . When the piston moves backwards, the ball  72  is lifted by negative pressure in the valve body  60 , allowing liquid to enter the valve body from the container  1  ( FIGS. 1 and 2 ). At the same time, the flapper valve  80  is closed, preventing air from entering the valve body through the nozzle  16 . When the piston moves forward, the ball  72  drops, sealing the ball valve and preventing liquid from reentering the container  1 . At the same time, liquid is pushed forward against the flapper valve  80  causing it to open. The fluid then enters the reduced volume annular chamber defined by the volume reducer  82  and the front of the valve body  60 . The liquid passes through this chamber and out of the nozzle  16 .  
         [0032]     According to the presently preferred embodiment, the forward moving duty cycle (the spray duty cycle) of the piston and the rearward moving duty cycle (the fill duty cycle) of the piston are unequal. In particular, this allows the piston to move more quickly during the fill duty cycle than during the spray duty cycle. In other words, the piston spends more time expelling fluid through the nozzle than it spends drawing fluid from the container into the valve body. This helps overcome the “pulsing” nature of certain prior art pumps and results in what appears to be a more continuous spray. According to the presently preferred cam arrangement, a 270° spray duty cycle and a 90° fill duty cycle is utilized. This arrangement is illustrated schematically in  FIG. 10  which is similar to  FIG. 5  with similar reference numerals (increased by 100) referring to similar parts. It can be seen in  FIG. 10  that the cam surface  156   d  has a downward sloped portion  156   d - 1  of approximately 90° and an upward sloped portion  156   d - 2  of approximately 270°. Though not shown in  FIG. 10 , it will be appreciated that the cam surface  156   c  has the same configuration as surface  156   d , but offset by 180°. Although the presently preferred embodiment uses a 270°/90° duty cycle, those skilled in the art will appreciate, however, that other unequal duty cycles could be used to obtain similar results. In particular, the duty cycle can be optimized for different kinds of fluids, optimizing the spray characteristics vs. the perceived pulsation of the spray. For example, if the fill duty cycle is longer than the spray duty cycle, this allows for a higher pressure spray resulting in finer atomization and/or greater spray distance at the cost of perceived pulsation.  
         [0033]     Further, according to the presently preferred embodiment, the transmission  26  is arranged so that the piston  64  cycles between two and ten cycles per second, and most preferably between 2.5 and 4 times per second. This, together with the spray duty cycle discussed above, results in an apparently constant stream at a relatively low pressure (5-200 psi).  
         [0034]     The spray head of the invention is well balanced, small, and is retrofittable to many existing fluid containers taking the place of a manual spray pump.  
         [0035]     There have been described and illustrated herein several embodiments of a battery operated spray head retrofittable to existing pump spray containers. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.