Abstract:
A spraying assembly is provided for delivering a coating material to a surface. The assembly of an embodiment comprises a mobile support structure, a mixing tank coupled to the support structure and a mixing device connected to the mixing tank. A mixture dispensing assembly has a conduit coupled to the mixing tank and a dispenser through which a flowable mixture is dispensed. The assembly has an hydraulic system having at least one closed hydraulic loop, a hydraulically-driven air compressor coupled to the hydraulic system, and a hydraulic pump assembly coupled to the closed loop of the hydraulic system. The hydraulic pump assembly is configured to pump the mixture at a selected flow rate from the mixing tank to the mixture dispensing assembly, and a remotely-actuated flow control assembly configured to control the flow rate of the mixture to the mixture dispensing assembly. The flow control assembly having a control unit adjustable by a user remote from the hydraulic pump to change the flow rate of the mixture to the dispenser.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This patent application is a non-provisional patent application claiming priority to U.S. Patent Application No. 60/799,463 and entitled Drywall Spraying Assembly, filed May 11, 2006, and it which is hereby incorporated in its entirety by reference thereto. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention is directed to equipment and methods for applying coating material to drywall or other surfaces.  
       BACKGROUND  
       [0003]     Drywall spraying equipment is typically designed to stir and mix drywall mud or other spray-on coatings that can be pumped through a hose and dispensed through a spray-gun or other spraying mechanism. The hoses are fairly long, so a user can work remotely from the tank. The pump is connected to the tank and the hose to move the mud through the hose to the dispensing gun. Prior art systems have experienced drawbacks; for example, the tanks with hoppers are typically relatively tall. Bags of drywall mud mix are typically 60-80 pound bags, which can be difficult to lift and pour into the hopper, particularly if the hopper is tall. Other systems have mixing paddles within the tank that often splash the mix as the mixer blades rotate within the tank. Other systems include hinged doors welded to the tanks to cover the top of the tank and these hinged doors are susceptible to damage. Other systems include motors and pumps that stick out from the tank&#39;s sidewall, thereby increasing the overall width of the unit.  
         [0004]     Other prior art systems have experienced drawbacks because the controls for the motors and pump system are provided on the trailer adjacent to the tank. If a worker is operating the spray-gun and dispensing the mud at a location remote from the tank and the worker needs to adjust the flow of the mud, the operator must stop spraying and walk back to the trailer so as to adjust the pump controls. This adjustment process is very inefficient and increases the time required to complete a job. Accordingly, there is a need for an improved drywall spraying system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a schematic isometric view of a drywall spraying assembly in accordance with an embodiment of the invention.  
         [0006]      FIG. 2  is a schematic cross-sectional view of a hopper, tank and frame of the assembly of  FIG. 1 .  
         [0007]      FIG. 3  is a side elevation view of a tank assembly of the drywall spraying assembly of  FIG. 1 , wherein the tank assembly is shown removed from the mobile support structure.  
         [0008]      FIG. 4  is an enlarged side elevation view of a locking door-hinge of the tank assembly of  FIG. 3 .  
         [0009]      FIG. 5  is an enlarged side elevation view of a lift handle on the door of the tank assembly of  FIG. 3 , wherein the door is shown in a closed position covering a grate on a hopper portion of the tank assembly.  
         [0010]      FIG. 6  is an exploded isometric view of the tank assembly of  FIG. 3 .  
         [0011]      FIG. 7  is an enlarged side elevation view of a tank support plate and a pump housing of the tank assembly of  FIG. 3 .  
         [0012]      FIG. 8  is a top plan view of the tank support plate of  FIG. 5  shown removed from the tank, the support plate having a plurality of mounting apertures forming a universal motor of mounting system.  
         [0013]      FIG. 9  is a schematic illustration of a hydraulic system of an embodiment of the assembly of  FIG. 1 .  
         [0014]      FIG. 10  is a schematic view of the drywall spraying assembly of  FIG. 1  and the hose and gun system with a remote controller in accordance with an embodiment of the invention.  
         [0015]     Appendix A—Photos of portions of an embodiment of a drywall spraying assembly. 
     
    
     DETAILED DESCRIPTION  
       [0016]     Embodiments of the present invention include an operator friendly drywall spraying assembly. Several specific details of the invention are set forth in the following description and in  FIGS. 1-10  to provide a thorough understanding of embodiments of the invention. One skilled in the art, however, will understand that the present invention will have additional embodiments, and that other embodiments of the invention may be practiced without one or more of the specific features described below. In other instances, well known structures, materials, or operations are not shown or described in order to avoid obscuring aspects of the invention.  
         [0017]      FIG. 1  is a schematic isometric view of a drywall spraying assembly  10  in accordance with an embodiment of the invention. The assembly includes a mobile support structure, such trailer  12  with an adjustable tow hitch  14 . The trailer  12  supports a tank assembly  15  that includes a tank  16  and a hopper  18 . The trailer  12  also supports a hydraulic system  20 , and an electrical system  22  coupled to the tank  16  and the hopper  18 . An elongated hose  24  is coupled to the tank  16  and to a pump  26  that drives mud from the tank to a distal end  28  of the hose  24 . A mud-disposing device, such as a handheld or pole gun  30 , is attached to the distal end  28  of the hose  24 .  
         [0018]     The hopper  18  is configured to receive dry mud mix. The hopper  18  has a grate  32  over the top  34  to prevent unwanted items from entering the hopper  18  in the illustrated embodiment, a tank assembly  15  has a door  36  positioned to cover the grate  32  and close out the hopper  18  when the door is in a closed position. The hopper  18  is connected to the tank  16  so the dry mix can be metered into the tank and mixed with water.  
         [0019]     As best seen in  FIGS. 3 and 4 , the door  36  of the illustrated embodiment is pivotally connected to the tank assembly  15  and is moveable between open and closed positions. The door  36  is connected to a locking hinge  31  with releasable lock portions  33  configured to releasably lock and door  36  in the open position. Accordingly, the door  36  will remain in the open position until a user actively moves the door to overcome the locking feature so that door can be closed. This locking hinge  31  provides an operator-friendly configuration that helps prevent the door  36  from inadvertently or prematurely move to the closed position. The door  36  also includes a lift handle  35  opposite the locking hinge  31 . The lift handle  35  is configured to allow a user to grasp and lift the door  36  toward the open position. The door  36  can also be balanced so the door can move easily and smoothly between the open and closed positions.  
         [0020]     The tank  16  of the illustrated embodiment is a stainless steel 200- or 300-gallon tank, although other size tanks can be used. For example, one embodiment of the assembly  10  can be provided with a 150-, 200-, 300-, 350-, 450- or 500-gallon tank. In one embodiment, the 150-, 200-, 300-, and 350-gallon tanks  16  all have the same size footprint, so any one of these tanks can be interchangeably mounted onto the same trailer  12 . This interchangeability of tanks having the same footprints during manufacturing or retrofit allows a single style of a trailer or other mobile support structure to be used, thereby reducing the cost of the assembly  10  and increasing manufacturing efficiency. Accordingly, fewer parts are needed for the systems in various configurations, so that the manufacturing costs of the unit are reduced. In one embodiment, the tank  16 , such as the larger 450- or 500-gallon tank, can be mounted on a skid configured to be installed on a vehicle. In another embodiment, the drywall spraying assembly  10  can include other mobile support structures onto which the tank  16  and the other components of the assembly are assembled, so as to provide a mobile unit that can be easily transported as a self-contained unit to different work sites.  
         [0021]     As best seen in  FIG. 2 , the tank assembly  15  includes the plurality of mixing paddles  42  rotatably disposed within the tank  16  and coupled to a mixing motor  44  mounted to the sidewall  43  of the tank  16 . In the illustrated embodiment, the tank  16  is a stainless steel J-tank. The mixing paddles  42  are mounted on a shaft  48  that extends across the interior  50  of the tank  16  and is coupled to the mixing motor  44 . The mixing paddles  42  are oriented at a selected angle relative to the shaft  48  and are configured actively to stir, fold, or otherwise mix a mud mixture (which is formed by dry mixture components combined with water). In one embodiment, the mixing paddles  42  have a connection rod  37  securely fastened generally perpendicular to the shaft  48  and blade portions  38  attached to the connection rod. The blade portions  38  are oriented at an angle in the range of 46-degrees to 50-degrees, inclusive, relative to the shaft  48 . In another embodiment, the blade portions  38  are oriented at approximately a 47-degree angle relative to the shaft  48 . The angular orientation and the shape of the mixing paddles  42  are such that the paddles minimize splashing of the mud during the mixing process, such that mud does not splash out of the open top  34  of the tank  16  in the event that the hinged door  36  is open.  
         [0022]     In the illustrated embodiment, the tank assembly  15  includes four mixing paddles  42 , although a greater or less number of paddles can be used in other embodiments. The four paddles  42  are arranged with two left paddles  42   a  on a left side of the tank&#39;s interior area, and two right paddles  42   b  on a right side of the interior area  50 . The two left paddles  42   a  are laterally offset from each other (i.e., not axially aligned) and radially offset from each other (i.e., they extend from the shaft radially away from each other). Similarly, the two right paddles  42   b  are laterally and radially offset from each other. The blade portions  38  on the two left paddles  42   a  are oriented so that when the blade portions move through the mud, the blade portions push and direct the mud in generally opposite directions during the mixing process. For example, one of the blade portions  38  on one of the left paddles  42   a  push the mud toward the right side of the interior area, and the paddle portions  38  on the other of the left paddles  42   a  push the mud the other direction toward the left side of the interior area  50 . The two right paddles  42   b  are similarly oriented to direct the mud in generally opposite directions during the mixing process. As a result, the mixing paddles  42  are able to mix the mud to a ready condition for spraying in a substantially shorter time period than achieved in conventional systems.  
         [0023]     The tank assembly  15  is configured so the tank  16  and hopper  18  arrangement have a low profile and are attached to the bottom portion of the trailers frame. The low profile tank  16  and hopper  18  have an uppermost edge that is substantially lower relative to the trailer  12  than experienced in a prior art. As a result, it is much easier for a user to lift heavy bags of mix and empty them into the hopper  18 . The grate  32  over the hopper  18  helps protect from the user putting their hands or arms into the hopper  18  during the mixing process. It also prevents a bag of mix or other items from inadvertently falling into the hopper  18 .  
         [0024]     The top  34  of the tank  16  is closed by the hinged door  36 . in one embodiment, the hinge  31  is configured to be a repairable and/or replaceable hinge such that in the event the door  36  or the hinge is damaged. The hinge  31  and/or the door  36  can be removed and replaced with a new hinge and door configuration. The door  36  is also a self-latching unit that provides for easy closure of the top  34  of the tank  16 .  
         [0025]     In the illustrated embodiment of  FIG. 1 , the tow hitch  14  on the trailer  12  is an adjustable six-point hitch configured to allow the connection member that attaches to a ball of a vehicle to be positionable at different heights relative to the frame of the trailer  12 . Accordingly, the tow hitch  14  allows the unit to be fitted to a wide range of makes and models of cars and trucks that have tow-ball configurations while allowing the trailer  12  to remain substantially level. The frame  39  of the trailer  12  has a hollow and sealed tubular portion  40  that defines a pressurized air chamber  41 . During construction, the tubular portion  40  of the frame  39  is built and sealed to provide a sealed chamber. Then, a sealing and anti-corrosion coating, such as paint, is sprayed into the tubular portion  40 . In one embodiment, an elongated applicator tube with a spray nozzle at the end is inserted all the way into the tubular portion  40  and the paint or other coating material is sprayed through that tube out of the nozzle in a substantially 360-degree spray pattern, thereby coating the inner surface of the frame&#39;s tubular portion  40 . As the material continues to spray out of the nozzle, the applicator tube is slowly drawn back out of the frame tubular portion  40 . As a result, the entire inside of the air chamber  41  is fully coated and sealed and protected. In one embodiment, the air chamber  41  in the trailer  12  frame is lined with a specially formulated paint for rust protection. The extra air storage provided inside the frame&#39;s air chamber  41  acts to hold consistent cool air pressure.  
         [0026]     The trailer  12  also includes a front grate  32  bolted in front of the tank  16  and provides a continuous surface up to the edge of the tank  16  and allows a user to stand on the grate  32  during operation. The grate  32  can be bolted onto the frame  39  and can be removed as needed for service on the lower portion of the stater tubes or other portions of the drywall spraying assembly  10  under the frame and  39 . This arrangement provides a user-friendly configuration data allows for easy and fast access to the various components of the assembly for general maintenance, repair, or replacement.  
         [0027]     The assembly of the illustrated embodiment has a hose rack  45  with three hooks  46  that provide for support of the elongated hose  24  when coiled up and in a stored position. The hose  24  can be a long hose, such as 100-200 feet, although other lengths of hoses could be used. The assembly  10  can be configured for providing two hoses that can be operated simultaneously. The assembly  10 , however, has a single hydraulic system  20  that operates to provide the mud to one or both of the hoses on demand.  
         [0028]     The hydraulic system  20  includes a hydraulic pump  26  coupled to the hose  24  and to the tank  16 . The hydraulic pump  26  of the illustrated embodiment is a progressive cavity pump configured to received a flow of the mud from and outlet  69  in the bottom of the tank  16  and to pump the mixed mud through the hose  24  to the gun  30  on the distal end  28  of the hose. As best seen in  FIG. 10 , the hydraulic pump  26  is coupled to a controller  52  that can be controlled by a user remote from the trailer  12 . In the illustrated embodiment, the controller  52  is a remotely controlled, wireless linear actuator controller configured to adjust the speed of the hydraulic fluid driving the pump  26  upon receiving signals from a remote signaling device, referred to as a control unit  54 . Other embodiments can use other remotely controlled controllers.  
         [0029]     The remote control unit  54  of the illustrated embodiment is a “wireless” control unit that communicates wirelessly with the controller  52  to control and/or adjust the speed of the hydraulic pump  26 , thereby adjusting the flow rate of the mud through the hose  24  and the gun  30 . In another embodiment, the control unit  54  can be hard wired to the controller  52  such as by a control line that extends along the hose  24 . In another embodiment, the control line can be an integral part of the hose. This remote control unit  54  allows the user to adjust the flow of mud without having to walk all the way back to the trailer  12  and adjust the pump  26  manually, thereby reducing the time it takes to complete a spraying job. In one embodiment, the remote control unit  54  is attached to the gun  30 . In another embodiment, the remote control unit  54  is attached to the distal end  28  of the hose  24  adjacent to the gun  30 . In another embodiment, the remote control unit  54  can be removably connected to the hose  24  such that a person can remove the remote control unit from the hose  24  and/or the gun  30 . In another embodiment, the remote control unit  54  is a handheld device carried by the user while still being able to remotely control the hydraulic pump  26  and the speed of the mud delivery to the gun  30 .  
         [0030]     As best seen in  FIGS. 6 and 7 , the tank assembly  15  includes a support plate  60  connected to the bottom of the tank  16  the support plate is configured to mount onto the trailer and  12  ( FIG. 1 ) or other mobile support device to securely fixed the tank in place. The support plate  60  of the illustrated embodiment is welded or otherwise securely fixed to the bottom of the tank  16 . The hydraulic pump  26  is mounted to the bottom of the support plate  60 . The support plate  60  is configured to provide additional rigidity to the tank  16  and to absorb and shield the tank from a torque generated by the hydraulic pump  26  during operation. Accordingly, the tank  16  is not exposed to these torsional forces and stresses, thereby resulting in a longer operational life of the tank.  
         [0031]      FIG. 8  is an enlarged top plan view of the support plate  60  removed from the tank. The support plate  60  of the illustrated embodiment includes a plurality of mounting holes  62  disposed about an enlarged central opening  64  through the support plate. The mounting holes  62  are arranged to form a universal mounting pattern that will allow anyone of a plurality of pumps can be mounted onto the support plate to pump the mud from the tank  16  through the hose  24  ( FIG. 1 ). The mounting holes  62  are spaced around the central opening  64  which is configured to allow the mud from the tank to pass their through into the hydraulic motor for pumping through the hose. Although the illustrated embodiment shows a series of five mounting holes  62  on each side of the central opening  64 , other embodiments can use other mounting hole configurations and arrangements to accommodate the selected mounting configurations for other pumps.  
         [0032]     Referring again to  FIG. 6 , the tank assembly  15  has a pump housing  66  sealably connected to the bottom of the support plate  60  in alignment with the central opening  64 . The pump housing  66  of the illustrated embodiment includes a seal or gasket  65  that engages the bottom of the support plate to form a seal therebetween. Accordingly, mud from the tank  16  exits the outlet  69  and enters the pump housing  66  through an inlet  68  to the pump  26  in the housing. In the illustrated embodiment, the pump housing  66  has apertures  67  at the ends through which portions of the pump extend (such as a drive shaft and stator tube). The pump housing  66  of the illustrated embodiment also includes a drain plug that provides access into the pump housing to drain mud therefrom. The pump housing  66  is easily excessive bull from under the trailer  12 , such that the pump housing can be easily and quickly removed to access the pump  26 , such as for routine cleaning and/or maintenance.  
         [0033]     In the illustrated embodiment of  FIG. 1 , an engine mounting plate and  74  is provided with a one-half inch plate having universal mounting templates configured to quickly and easily receive engines made by multiple different manufacturers. Accordingly, different engines can be easily and quickly mounted to the mounting plate  74  depending upon an engine selected by a potential customer.  
         [0034]      FIG. 9  is a schematic illustration of the hydraulic system  20  of an embodiment of the assembly of  FIG. 1 . The hydraulic system  20  of the illustrated embodiment is a single-stage, high pressure hydraulic system with approximately 2,000 PSI. The hydraulic system  20  includes a hydrostatic pump assembly  82 , which is driven by a power plant, such as a diesel or gas-powered motor  75  ( FIG. 1 ). The hydrostatic pump assembly  82  is configured to drive the hydraulic pump  26  attached to the bottom of the tank assembly  15  ( FIG. 1 ), as discussed above to provide the selected flow rate of the mud delivered to the gun. The hydrostatic pump assembly  82  also drives the mixer motor  44  to mix the mud within the tank, and also with the hydraulically powered air compressor  86  that provides the pressurized air provided to the gun for spraying of the mud.  
         [0035]     In the hydraulic system of  80  in the illustrated embodiment includes a first closed loop  88  connected to a hydrostatic pump device  90  and to the pump  26 , discussed above. The hydrostatic pump device  90  is adjustable to provide hydraulic fluid at a selected flow rate to the pump  26 , thereby controlling pump&#39;s operating speed and the associated mud flow rate. The first closed loop  88  also includes an on-off valve switch  92 . The switch  92  can be activated to direct hydraulic fluid to the pump  26  when the valve switch is in the “on” position. The switch and  92  is also configured to allow a hydraulic fluid to bypass the pump  26  when the switch is in the “off” position.  
         [0036]     In one embodiment, an electric bypass device  94  connected to the switch  90 . The bypass device  94  has a pressure sensor connected to the hydraulic fluid line and is configured to automatically move the switch  92  to the “off” position when the pressure sensor detects the pressure within the first closed loop exceeds a maximum allowable level. When the switch  92  is moved to the “off” position, the hydraulic fluid is allowed to substantially really circulate back to the hydrostatic pump  82  through the closed loop system. This bypassing of the hydraulic fluid prevents over pressurization of the first closed loop  88 , which could result in damage to the hydraulic lines or components therein. This bypassing of the hydraulic fluid also allows the hydraulic fluid to remain within a cool operating temperature, particularly during extended use of the assembly  10 .  
         [0037]     The hydraulic system  20  has a second closed loop  94  connected to a second hydrostatic pump assembly  98 . The second closed loop  94  is connected to the mixer motor  44  that drives the mixing paddles  42  ( FIG. 2 ), as discussed above. The second hydrostatic pump device  98  can be adjustable to control the speed of the mixing paddles.  
         [0038]     When the first or second hydrostatic pump devices  90  or  98  is turned off, the hydraulic fluid does not flow through the respective loop  88  or  94 , thereby allowing the hydraulic fluid to dissipate accumulated heat. Accordingly, additional cooling systems are not needed to coolly the hydraulic fluid in the closed loops.  
         [0039]     The hydraulic system  20  has a third loop  100  connected to another hydrostatic pump assembly  102 . This third loop  100  is an open loop that draws hydraulic fluid from a reservoir  104 , directs the hydraulic fluid through a pressure relief valve  106  to the air compressor  86 . The air compressor  86  is configured to provide pressurized air to the air chamber  41  ( FIG. 1 ) for use in spraying the mud from the gun  30  ( FIG. 1 ), as discussed above. The third loop  100  also has a filter assembly  108  down stream of the air compressor to filter the hydraulic fluid before it returns to the reservoir  104 .  
         [0040]     In the illustrated embodiment, the hydraulically-driven air compressor is coupled directly to the motor  75  ( FIG. 1 ) via a modified flexible lovejoy connection, such that the compressor does require belts, which have a tendency to loosen or wear out over time. In addition, the hydraulically-driven air compressor  86  is configured to operate at a constant speed (i.e., rpm) and to provide consistent air pressure. Accordingly, the hydraulic system  20  is such that an operator can not over-speed the system, thereby protecting against excessive or accelerated wear of the equipment.  
         [0041]     The machine is balanced for use with one or more hoses simultaneously. In one embodiment, a slider valve is provided at the pump  26  housing between the tank  16  and the pump  26 . The slider valve can be activated to stop  34  the flow of drywall mud or other material to be sprayed to allow for easy servicing of the pump  26 . An easy, clean, and deluxe texture filter can be provided that is coupled to the pump  26 .  
         [0042]     Additional features of the system include Teflon bushings provided between the tanks and the drive shaft  48  coupled to the paddles  42 . No additional bearing assemblies are needed for double action or dual-independent mixing tank  16 s or independent mixing paddles  42 .  
         [0043]     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited, except by the appended claims.