Abstract:
A multi-container manual-pump-operated backpack sprayer including an open-topped backpack enclosure, a plurality (preferably three) modular liquid containers removably seated in the enclosure, a hand-lever-operated pump/accumulator combination, and a user-controllable manifold for selecting a particular chemical from the containers for administration through a spray wand. Chemical is carried to the pressure chamber by manually pumping. The pump draws liquid from a manifold-selected supply container outward through tubes to the manifold, which has a console of valves. Separate return tubes are provided for each chemical from the manifold back to the containers of origin, and the manifold allows convenient flushing of each chemical back to its container of origin. This ensures that chemicals are not mixed or cross-contaminated and avoids waste since all residual is returned back to its respective container. The manifold is conveniently carried at the hip for ease of access.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present invention derives priority from U.S. provisional application No. 61/589,622 filed Jan. 23, 2012. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to portable commercial-grade agricultural sprayers and, more particularly, to a portable backpack-style manual-pump-operated agricultural sprayer for spraying through a hand-carried spray wand any of a variety of different chemicals from modular containers seated in a backpack housing. 
     2. Description of the Background 
     There are a wide variety of sprayers available for application of liquid fertilizers and pest control solutions, including backpack sprayers, hand sprayers, and truck-mounted spray tank systems. The simplest sprayers are designed for consumer use and typically comprise a single container with a piston pump and hand-carried wand. However, these sprayers are typically one or two gallons in size and are meant for simply maintaining a lawn or garden. The lawn and landscape industry demand more efficient commercial-grade sprayers for multiple and larger jobs, and backpack sprayers have become standard equipment in most commercial operations. Backpack sprayers afford great mobility for larger jobs on terrain where stationery equipment can&#39;t go. Backpack sprayers typically use a polyethylene plastic chemical-holding tank with a capacity of up to four gallons, with an attached shoulder harness and hand-carried spray wand. 
     Although motorized-pump backpack sprayers or gas cartridge (CO 2 ) powered sprayers exist, the most popular commercial-grade sprayers are manually powered backpack-style sprayers in which the chemical-holding tank is equipped with a pump and pumping lever. The chemical-holding tank itself is not typically pressurized by the pump, but rather each tank has a smaller, pressurizing chamber. Liquid is carried from the chemical-holding tank to the pressurizing chamber by the pump, where the chemical remains until the operator squeezes a trigger-valve on the spray wand. Several pump types are available, but the two most common are piston and diaphragm pumps. 
     Relatively high pressures can be reached with manual backpack sprayers, although most operate at 15 to 95 psi. However, since pressure gradually decreases as the tank empties and spray is applied, the operator must periodically pump the device to make sure that pressure remains constant and that enough flow reaches the nozzle at the desired pressure. 
     Such backpack sprayers are not new. They date back at least to 1888 (as per U.S. Pat. No. 383,261). However, more recently backpack sprayers have grown in popularity and a number of patents have issued for design improvements. 
     For example, U.S. Pat. No. 2,162,057 to Brandt issued Jun. 13, 1939 shows a backpack sprayer having a tank with internal accumulator. A hand-operated piston pump pumps liquid from the container tank to the pressure vessel. As liquid is pumped in from the bottom, the air inside is compressed at the top and this provides a pressure source for discharging the liquid out from the spray nozzle. 
     U.S. Pat. No. 5,335,853 to Wirz issued Aug. 9, 1994 shows a backpack sprayer similar to the &#39;057 patent to Brandt but incorporating a double-acting piston pump. Upon reciprocation of the piston either direction there is pumping of liquid from the container tank to the pressure vessel. 
     U.S. Pat. No. 5,284,300 to Gries et al. issued Feb. 8, 1994 shows a portable spray system with backpack carriage containing two water storage containers. 
     U.S. Pat. No. 5,636,791 to Leer (Gilmour, Inc.) issued Jun. 10, 1997 shows a backpack sprayer with an adjustable valve  43  that allows the operator to adjust the pressure release valve  42  of the container to a specific pressure. 
     U.S. Pat. Nos. 5,755,361 and 5,857,618 both to Restive et al. (D.B. Smith, Inc.) issued May 26, 1998 and Jan. 12, 1999, respectively shows a backpack pump sprayer with an expanding accumulator pump (internal balloon-like bladder) that elastically ejects liquid. 
     U.S. Pat. No. 7,793,804 by McGiveron (Chapin Manufacturing, Inc.) issued Sep. 14, 2010 shows a dual-action pump assembly for sprayers that overcomes a “hydrolock” problem caused by residual chemical by a one-way valve that lets in additional air during the suction part of the cycle. 
     U.S. Pat. No. 7,556,210 to Mandell et al. issued Jul. 7, 2009 shows a portable mixing sprayer in a wheeled or motorized unit. 
     R&amp;D Sprayers produces its Model 315FG (Flash Gordon Model) which is a backpack sprayer designed to dispense from multiple bottles using CO 2  cylinder pressurization. 
     While these prior art devices are useful to a degree, they still suffer from certain drawbacks in that they do not provide sufficient durability and reliability without materially adding to the cost or weight of the device. The primary design goals of any manual pump-operated backpack sprayer are performance, reliability, durability, ease of use, light weight, low cost, and ease of manufacture. In addition, one notable problem with conventional manual pump-operated backpack sprayers has been the difficulty in changing chemicals. A typical lawn care treatment may require application of several different chemicals successively, and upon each changeover of chemical the sprayer tank must be drained and refilled. This is cumbersome and if not done thoroughly there is a high propensity for cross-contamination. Some chemicals, notably broad-leaf herbicides, can be difficult to fully rinse from spray tanks due to their affinity for the plastic. Moreover, residual chemicals typically remain in the compression chamber, sprayer wand and/or hose. Operators are forced to fully wash the inside of the sprayer tank and flush all internal components between applications, and this is very tedious. Still, if any residual remains serious problems can result. Upon the next successive application of fertilizer after a herbicide, any residual herbicide will have the opposite intended effect of the fertilizer. Many operators keep separate sprayers for separate chemicals for this very reason. Thus, of course, is redundant and expensive, and so what is needed is an improved portable backpack-style manual-pump-operated agricultural sprayer for spraying a variety of different and/or mixed chemicals from modular containers all seated in a backpack housing, through a hand-carried spray wand. It would be even more advantageous to provide such a sprayer with back-flush capability to clear the sprayer wand and hose upon changeover, thereby reducing or eliminating risk of cross-contamination. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a portable backpack-style manual-pump-operated agricultural sprayer with multiple modular chemical containers all removably seated in a backpack housing and a manifold assembly for spraying a variety of different (and/or mixed) chemicals from the container, without the need for draining and changing chemicals between applications or washing their interior to avoid cross-contamination. 
     It is another object to provide the foregoing in a compact backpack-style sprayer footprint with manual pump lever and hand-carried spray wand. 
     It is another object to provide an operator-controlled manifold assembly for selection of any one (or a mixture) of the chemicals from the containers, and to provide said manifold assembly with back-flush capability to clear the sprayer wand, pump, pressure chamber and hose, emptying residual chemical back into the appropriate container upon changeover, thereby reducing or eliminating any risk of mixing chemicals and cross-contamination. 
     It is yet another object to provide a portable backpack-style manual-pump-operated agricultural sprayer as described above in which all operator-controls are easily accessible to permit control/changeover or adjustment during spraying without the need to take the sprayer off the operator&#39;s back. 
     In accordance with the above-described objects, an improved multi-container manual-pump-operated backpack sprayer is provided including an open-topped aluminum backpack enclosure, a plurality (preferably three) modular liquid containers removably seated in the enclosure, a hand-lever-operated piston pump and pressure chamber (or “accumulator”), a user-controllable manifold for selecting a particular chemical from the containers (or alternatively, for mixing), and a spray wand. Chemical is carried to the pressure chamber by manually pumping the pump. The pump draws liquid from a manifold-selected supply container outward through tubes to the manifold, which has a console of valves. Separate return tubes are provided for each chemical from the manifold back to the containers of origin, and the manifold allows convenient flushing of each chemical back to its container of origin. This ensures that chemicals from the containers are not mixed or cross-contaminated, and avoids wasting chemicals as all residual is returned back to its respective container. The manifold valves are carried on a waist belt at the hip for ease of control during spraying, without need to take off the backpack sprayer. 
     The above and other objects, features and advantages of the present invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment and certain modifications thereof, in which: 
         FIGS. 1-2  show a right-side perspective view and left-side perspective view, respectively, of the manual pump-operated sprayer  1  according to the present invention. 
         FIG. 3  is an enlarged view of enclosure  4  with three removable containers  6  arranged side-to-side. 
         FIGS. 4 and 5  are left-side perspective view and right-side perspective view of the piston-based pump  10  and integral pressure chamber  12  mounted to the rear of enclosure  4 . 
         FIG. 6  is a side close-up view of the manifold assembly  50  and sprayer wand  40 . 
         FIG. 7  is a side cross-section of the manifold assembly  50 . 
         FIG. 8  is a top cross-section of the manifold assembly  50 . 
         FIG. 9  is an end view of the manifold assembly  50 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is a portable backpack-style manual-pump-operated agricultural sprayer for spraying a variety of different and/or mixed chemicals from modular containers seated in a backpack-style enclosure, out through a hand-carried spray wand. The present sprayer employs a dispensing system with an operator-controlled manifold having convenient controls for selecting a desired chemical to be sprayed, plus back-flush capabilities to clear the sprayer wand, hose, pressure chamber and manifold upon changeover, thereby eliminating risk of mixing and cross-contamination. 
       FIGS. 1-2  show a right-side perspective view and left-side perspective view, respectively, of the manual pump-operated sprayer  1  of the present invention. Sprayer  1  generally comprises a five-wall open topped rectangular enclosure  4  with three removable polyethylene chemical containers  6  seated side-to-side inside. The sprayer  1  may be scaled as desired to accommodate more or fewer containers  6 , as few as two and as many as desired subject to weight constraints, as a matter of design choice. Each container  6  may be a conventional 5 liter (L) to 10 L leak-proof polyethylene (e.g., HDPE) tank, preferably rectangular for efficient containment in rectangular enclosure  4 . Enclosure  4  is equipped on one side with a backpack-style belt and shoulder harness  8  that is padded to rest comfortably against the operator&#39;s back, with straps that slip over the operator&#39;s shoulders and a waist strap for correctly positioning and securing the device snuggly to the operator. Harness  8  may be any suitable commercial backpack harness including the shoulder straps and the waist strap with means for securing the harness to the back of the enclosure  4 . The containers  6  are equipped with an upper opening capped by a removable screw-on closure through which the desired chemicals can be added to the containers  6 . 
     Mounted to the rear of the enclosure  4  is a piston-based pump  10  and integral pressure chamber  12 . An angled handle bar  14  is formed with a lever section typically 18-to-24 inches in length and extending to a distal hand grip suspended at the operator&#39;s hip. The handle bar  14  runs to a corner of enclosure  4  where it is formed with a 90-degree angled bend, continuing along a rotational section that is as long as necessary to traverse the enclosure  4  from side-to-side, extending about an inch on each side. The rotational section of the handle bar  14  is pivotally mounted to the bottom of the enclosure  4  by insertion through opposing holes having bearings inserted therein to facilitate rotation. The rotational section of the handle bar  14  is connected by an internal linkage-assembly to the bottom of piston-pump  10 . Thus, the operator can manually reciprocate the lever section of handle bar  14  in an up-and-down motion to cause the rotational section to rotate, causing the linkage assembly to reciprocate the piston in piston pump  10 . This pressurizes pressure chamber  12  and pumps chemical out of a selected one of the containers  6 . The chemical is pumped through a manifold assembly  50  (as will be described) and into pressure chamber  12 . A length of flexible hose  22  connects the pressure chamber  12  outlet to a hand-carried trigger-operated spray wand  40  through which the pressurized chemical is sprayed. The wand  40  is equipped with a conventional hand-operated trigger-valve  42  and distal spray jet nozzle by which the operator directs and controls the spray as desired. Once the containers  6  of backpack sprayer  1  are filled with the desired chemicals, the operator can select the chemical to be sprayed via the manifold assembly  50 , move the handle bar  14  up to pull chemical from a selected container  6  into the piston pump  10 , and down to pressurize the chemical into the pressure chamber  12 . The operator&#39;s other hand is used to hold the wand  40 , and to activate and direct the valve  42  and nozzle to control and direct the spray. 
       FIG. 3  is an enlarged view of enclosure  4  with three modular-removable containers  6  arranged side-to-side inside. Containers  6  are preferably 5 L-to-10 L high density plastic clear/frosted containers to allow viewing of the chemical contents. These flattened rectangular chemical containers, typically formed of HDPE, are commercially available from multiple sources. The containers  6  are equipped with an upper opening capped by a removable cap  16  through which the chemicals can be added to the containers  6 . The cap  16  is equipped with a pass-through hose coupling  30  which feeds a hose to the bottom of the container  6  for supply of chemical therefrom. The hose couplings  30  preferably include a quick-disconnect elbow  31  (see inset) to allow easy detachment from cap  16  for removal of the hoses  35 , in this case elbow  31  being held captive to cap  16  by a detent-yoke  32  that unclips to allow removal of the elbow  31  and hose  35 . Three chemical supply hoses  35  lead from each hose coupling  30  all the way to manifold assembly  50 , and each supply hose  35  or cap  16  is preferably color-coded at both ends with a colored label  33  for easy visual correlation of hose  35  to chemical. 
     Since containers  6  are flat and uniformly-sized, they are stackable and fit snugly side-to-side within the enclosure  4 . The enclosure  4  is itself preferably formed of aluminum sheet, e.g., 24 gauge smooth finish, formed and welded as needed into an open-topped rectangular enclosure adapted for slidable top-load insertion of the three containers  6 . The enclosure also includes a raised floor  41  beneath which the handle bar  14  and a linkage-assembly to piston-pump  10  are mounted. The handle bar  14  passes through the sides of the enclosure  4  beneath the raised floor  41  and is pivotally-mounted therein by two panel-mounted bearing collars  62  attached in holes in the enclosure  4  side-panels beneath floor  41 . The handle bar  14  extends outward from the left-side of enclosure  4  (obscured in  FIG. 3 ) for operator-actuation. The piston-based pump  10  and integral pressure chamber  12  are mounted by yoke-brackets to the rear of enclosure  4  as shown. 
       FIGS. 4 and 5  are left-side perspective view and right-side perspective view of the piston-based pump  10  and integral pressure chamber  12  mounted to the rear of enclosure  4 . Both piston-based pump  10  and integral pressure chamber  12  may be any suitable commercially-available components such as, for example, Birchmeier™ six (6) bar pressure, high flow rate, externally mounted piston and accumulator assembly. In this case the piston pump  10  is integral to the pressure chamber  12 . Down-stoke on the piston (that is, pulling up on the handle bar  14 ) inducts chemical from the large containers  6  into the piston pump  10  cylinder chamber through hose  36  and a one-way valve  17  (see  FIG. 4 ). Up-stroke of the piston (that is, pushing down on the handle bar  14 ) pushes and pressurizes the chemical into the pressure chamber  12 . Additional up and down strokes can be utilized to both push more chemical into and increase the pressure within the pressure chamber up to the rated (6 bar) pressure. Accordingly, the operator has the option of more or less continuous pumping of the handle bar  14  to create a more or less steady stream of chemical at constant pressure. Chemical in the pressure chamber  12  is ejected through outlet  13 . 
     As seen in  FIG. 5 , a grease port  54  is provided for lubrication of the piston pump  10 . 
       FIG. 6  is a side close-up view of the manifold assembly  50  and sprayer wand  40 . The manifold assembly  50  comprises a matrix of manually-operated valves  52 - 58  having thumb-twist-knobs for ease of operation. Certain valves are pass-through ON/OFF valves and some are diverter valves capable of diverting a chemical to one of two outputs. Valve  58  is a plastic ON/OFF pass-through valve with a finger twist-knob for ease of operation, and it is connected to an external port through a one-way check valve  63  to provide air intake during the backwash process. The check valve  63  (see  FIGS. 7 ,  9 ) allows air intake but not air/chemical escape. At least the six diverter valves  52 - 57  are required to manifold three chemical containers  6 . The input of three diverter valves  52 ,  54 ,  56  is connected to the input of three respective diverter valves  53 ,  55 ,  57 , each at an input junction. Each of the three hoses  35  from each of the three containers  6  is connected a corresponding chemical input junction  67 ,  45 ,  23  between the paired diverter valves  52 / 53 ,  54 / 55 ,  56 / 57 . The outputs of diverter valves  52 ,  54 ,  56  are connected in series as shown, and through the pass-through valve  58  to the port/check valve  63 . Similarly, the outputs of diverter valves  53 ,  55 ,  57  are connected in series as shown, and (as seen in  FIG. 3 ) on through a short length of hose  37  that runs to a junction at a T-connector  38  interrupting the hose  22  to spray wand  4 . Preferably, the T-connector  38  is located as close as possible to spray wand  4 . Thus, the operator may selectively open any one of the spray valves  52 ,  54 ,  56  in order to divert chemical from a respective selected container  6  back to the piston pump  10 . Upon pumping, the chemical exits pump  10  through main output hose  22  and travels to the spray wand  40  for release by trigger  42 . To conveniently changeover to another chemical, the opened spray (diverter) valve  52 ,  54  or  56  is closed, the corresponding backflush (diverter) valve  53 ,  55 ,  57  is opened along with the ported one-way valve  58 , and the handle bar  14  is pumped in order to backflush (by air suction) all existing chemical still in the main output hose  22 , pump  10 , and manifold  50  back into the proper container  6 . After backflushing the corresponding backflush valve  53 ,  55 ,  57  may be closed and a different spray valve  52 ,  54  or  56  opened to spray a different chemical from containers  6 , thereby minimizing any risk of chemical mixing. 
     Importantly, the manifold assembly  50  is located remotely from enclosure  4 , connected thereto by tubes  33 ,  36 ,  22  a few feet in length. This provides a significant advantage, allowing the manifold  50  to be conveniently suspended from the shoulder/waist harness  8  by a strap  82 , thereby positioning the manifold assembly  50  and its controls  52 - 58  at the operator&#39;s hip for convenient access. The hip-height handle bar  14  on one side in combination with the inline manifold  50  and sprayer wand  40  on the other side results in a comfortable two-handed carrying of the sprayer  1 , and the operator can release the wand  40  to adjust the manifold  50  and easily regain the wand  40 . 
     Additionally, the remote location of manifold  50  in conjunction with the location of junction  38  and T-connector  39  (as close as possible to spray wand  4 ) maximizes the effectiveness of the backflush, essentially draining residual chemical as far up as the spray wand  4  back into its appropriate container  6 . Again, operation of the manifold control panel  52 - 58  is color-coded by labels  33 . 
     The spray wand  40  may be any conventional trigger  42 -operated wand with distal spray nozzle. 
       FIGS. 7-9  are a side cross-section, top cross-section, and end view of the manifold assembly  50  illustrating the matrix of manually-operated valves  52 - 58 . Six valves  52 - 57  are plastic angle hose diverter valves with thumb-twist-knobs as shown. Each of the three hoses  35  from each of the three containers  6  is connected to a T-junction  67 ,  45 ,  23 , respectively, between the paired diverter valves  52 / 53 ,  54 / 55 ,  56 / 57 . The outputs of diverter valves  52 ,  54 ,  56  are connected in series as shown, and through the pass-through valve  58 . Diverter valves  52 ,  54 ,  56  apply suction from pump  10  and hose  36  into the appropriate hoses  35  of the three containers  6 . Thus, any of the three spray valves  52 ,  54 ,  56  may be opened to spray chemical from the selected container  6 . Down-stoke on the piston (that is, pulling up on the handle bar  14 ) inducts chemical from the large containers  6  through a select hose  35 , up through select junction  67 ,  45 ,  23 , through the open spray valve  52 ,  54 ,  56 , back through hose  36  into the pump  10  for spraying out through hose  22  and wand  40 . 
     Similarly, the outputs of diverter valves  53 ,  55 ,  57  are connected in series as shown to hose  37 . Diverter valves  57 ,  55 ,  53  divert/backflush chemical returning from spray wand  40  through T-connector  39 , junction  38  and hose  37  into the appropriate hose  35  for return to the proper one of the three containers  6 . To changeover to another chemical, the opened spray valve  52 ,  54  or  56  is closed, the corresponding backflush valve  53 ,  55 ,  57  is opened along with the ported one-way valve  58 , and the handle bar  14  is pumped in order to backflush (by air suction) all existing chemical still in the main output hose  22 , pump  10 , and manifold  50  back into the proper container  6 . After backflushing the corresponding backflush valve  53 ,  55 ,  57  may be closed and a different spray valve  52 ,  54  or  56  opened to spray a different chemical from containers  6 , thereby minimizing any risk of chemical mixing. 
     One skilled in the art should understand that the above-described sprayer  1  is designed to reduce or eliminate inadvertent mixing of chemicals that should not be mixed. If, on occasion, an application of chemicals calls for onsite mixing of two or three chemicals this can be accomplished simply by making the spray valves  52 ,  54 ,  56  adjustable-variable-flow valves, thereby allowing the operator to open any one, two or all three in varying degrees to mix the chemicals in containers  6 . 
     It should now be apparent that the manual pump-operated backpack sprayer  1  of the present invention allows selective spraying of different chemicals from any of a plurality of containers  6  in successive applications without ever taking off the sprayer. Moreover, it provides full and convenient control over the selected chemical, as well as full backflush capabilities so that operators do not need to wash the inside of the sprayer tank and flush all internal components between applications. Backpack sprayer  1  reduces the risk of cross-contamination and avoids the need to keep separate sprayers for separate chemicals. 
     Having now fully set forth the preferred embodiments and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is to be understood, therefore, that the invention may be practiced otherwise than as specifically set forth in the appended claims.