Patent Grant
9016599
The present invention is related to liquid dispensing systems. In particular, the present invention relates to pumping mechanisms for paint sprayers.
Sprayers are well known and popular for use in painting of surfaces, such as on architectural structures, furniture and the like. Airless paint sprayers provide the highest quality finish amongst common sprayer systems due to their ability to finely atomize liquid paint. In particular, airless paint sprayers pressurize liquid paint to upwards of 3,000 psi [pounds per square inch] (˜20.7 MPa) and discharge the paint through small, shaped orifices. Typical airless sprayer systems, however, require a large stationary power unit, such as an electric motor, a gasoline motor or an air compressor, and a large stationary pumping unit to generate such large pressures. The power unit is connected to a stationary paint source, such as a 5 gallon (˜18.9 liter) bucket, and a spray gun. These stand units, as they are commonly referred to, are expensive due to heavy duty construction, numerous components and manufacturing costs, but are well suited for painting large areas that require high quality finishes.
It is also desirable to paint smaller areas for which it is not desirable or feasible to set up a stationary stand unit system. For example, it is desirable to provide touch-up and trim areas having finishes that match areas originally painted with a stand unit. Various types of handheld sprayer systems and units have been developed to address such situations. For example, buzz guns or cup guns, as they are commonly referred to, comprise small handheld devices electrically powered by connection to a power outlet. For example, some handheld units use piston pumps that are actuated using crank and rod assemblies or bevel gear assemblies, as described in U.S. Pat. No. 2,488,789 to Williams and U.S. Pat. No. 2,629,539 to Drewes, Jr., respectively. These pumping mechanisms, however, have many intricate parts that increase the cost and size of manufacturing handheld units beyond feasibility.
There is, therefore, a need for a pumping mechanism that, among other things, reduces the expense of manufacturing airless sprayers.
The present invention is directed to a fluid dispensing device comprising a housing body, a reciprocating piston fluid pump, a primary drive element, a wobble assembly and a spray tip. The reciprocating piston fluid pump has a piston disposed within a pumping chamber inside the housing body. The primary drive element is coupled to the housing body to provide a rotary input. The wobble assembly connects the primary drive element to the reciprocating piston fluid pump to convert the rotary input into reciprocating input to the piston. The spray tip connects to an outlet of the pumping chamber.
Fluid container 16 is provided with a fluid that is to be sprayed from spray gun 10. For example, fluid container 16 is filled with a paint or varnish that is fed to spray tip assembly 14 through coupling with lid 36. Battery 26 is plugged into battery port 38 to provide power to drive element 20 within housing 12. Trigger 24 is electrically connected to battery 26 and drive element 20 such that upon actuation of trigger 24 a power input is provided to pumping mechanism 18. Trigger 24 is disposed in handle 34, which comprises a pistol grip-type handle. Pumping mechanism 18 draws fluid from container 16 and provides pressurized fluid to spray tip assembly 14. Connector 32 couples spray tip assembly 14 to pump 18 at an outlet port of housing 12. Tip guard 28 is connected to connector 32 to prevent objects from contacting high velocity fluid output from spray tip 30. Spray tip 30 is inserted through bores within tip guard 28 and connector 32 and includes a spray orifice that receives pressurized fluid from pumping mechanism 18, which is powered by drive element through wobble assembly 22. Spray tip assembly 14 provides a highly atomized flow of fluid to produce a high quality finish. Pressure relief valve 23 is connected to pumping mechanism 18 to open the mechanism to atmospheric pressure.
Pumping mechanism 18, drive element 20, wobble assembly 22, gearing 56 and valve 52 are mounted within housing 12 and supported by various brackets. For example, gearing 56 and wobble assembly 22 include bracket 60 which connects to bracket 62 of pumping mechanism 18 using fasteners 64. Valve 52 is threaded into bracket 62, and connector 32 of spray tip 30 is threaded onto valve 52. Spray tip 30, valve 52, pumping mechanism 18 and drive element 54 are supported within housing 12 by ribs 66. In other embodiments of spray gun 10, housing 12 includes ribs or other features for directly supporting gearing 56 and wobble assembly 22 without the use of bracket 60, as shown in
To operate gun 10, fluid container 16 is filled with a liquid to be sprayed from spray tip 30. Trigger 24 is actuated by an operator to activate drive element 20. Drive element 20 draws power from battery 26 and causes rotation of a shaft connected to gearing 56. Gearing 56 causes wobble assembly 22 to provide an actuation motion to pumping mechanism 18. In particular, wobble assembly 22 converts rotational power of drive element 20 into reciprocating power for pumping mechanism 18.
Pumping mechanism 18 draws liquid from container 16 using suction tube 48. Excess fluid not able to be processed by pumping mechanism 18 is returned to container 16 through priming valve 23 and return line 50. Pressurized liquid from pumping mechanism 18 is provided to valve 52. Once a threshold pressure level is achieved, valve 52 opens to allow pressurized liquid into barrel 46 of spray tip 30. Barrel 46 includes a spray orifice that atomizes the pressurized liquid as the liquid leaves spray tip 30 and gun 10. Barrel 46 may comprise either a removable spray tip that can be removed from tip guard 28, or a reversible spray tip that rotates within tip guard 28.
Drive shaft 76 is inserted into bushing 80 such that gear 78 rotates when drive element 20 is activated. In various embodiments of the invention, bushing 80 and gear 78 are integrally formed as one component. Bushings 86 and 88 are inserted into a receiving bore within bracket 60, and shaft 84 is inserted into bushings 86 and 88. Gear 82 is connected to a first end of shaft 84 to mesh with gear 78, and gear 90 is connected with a second end of shaft 84 to mesh with gear 94. In various embodiments of the invention, gear 82, shaft 84, gear 90 and bushing 92 are integrally formed as one component. Sleeve 102 is inserted into a receiving bore within bracket 62, and pin 100 is inserted into sleeve 102 to support wobble assembly 22. Wobble assembly 22 uses a few easily manufactured and assembled components to complete power transmission between drive element 20 and pumping mechanism 18.
Bearing assembly 98 connects pin 100 to connecting rod 96. Connecting rod 96 couples with first piston 72. First piston 72 and second piston 74 are inserted into piston sleeves 102 and 108, respectively, which are mounted within pumping chambers within bracket 62. Valve seal 106 and sleeve 108 seal the pumping chambers. Fasteners 64 are inserted through bores in bracket 62 and bushings 130 and threaded into bracket 60. First valve cartridge 112 is inserted into a receiving bore in bracket 62. First spring 120 biases valve stem 128 against cartridge 112. Similarly, second valve cartridge 122 is inserted into a receiving bore in bracket 62 such that second spring 128 biases valve stem 126 against bracket 62. Valve cartridges 112 and 122 are removable from bracket 62 such that valve stems 118 and 126 can be easily replaced. Seals 114 and 116 prevent fluid from leaking out of valve 68, and seat 124 prevents fluid from leaking out of valve 70. Valve 23 is inserted into a receiving bore in bracket 62 to intersect fluid flow from pistons 72 and 74.
Bearing assembly 98 includes outer race 98A, inner race 98B and bearing set 98C. Outer race 98A adjoins an inner surface of yoke 139. Inner race 98B adjoins an outer surface of wobble seat 136. Outer race 98A and inner race 98B include troughs, such as hemispherical or v-shaped troughs, in which bearing set 98C is disposed. Bearing set 98C comprises a plurality of ball bearings configured to roll between outer and inner races 98A and 98C. Outer race 98A, inner race 98B and bearing set 98C comprise an assembled unit such that bearing assembly 98 is preassembled. Bearing assembly 98 can then be press fit around wobble seat 136 and yoke 139 can be press fit around bearing assembly 98. In other embodiments, a bearing can be integrated into connecting rod 96 and land 132, similar to what is shown in
Gear 94 rotates land 132 and pin 100, which rotates within sleeve 102 and bushing 134. Wobble seat 136 comprises a cylindrical-like structure having a surface revolved about an axis that is offset or tilted at an angle from the axis about which hub 101 and pin 100 rotate. As hub 101 revolves, the axis of land 132 orbits the axis of pin 100, making a cone-like sweep. Bearing assembly 98 is disposed in a plane transverse to the axis of wobble seat 136. As such, bearing assembly 98 undulates, or wobbles, with respect to a plane transverse to pin 100. Connecting rod 96 is connected to the outer diameter end of bearing assembly 98, but is prevented from rotating about pin 100 by ball 138. Ball 138 is connected to piston 72, which is disposed within a piston seat in bracket 62 such that rotation is prevented. Ball 138 is, however, permitted to move in the axial direction as bearing 138 wobbles. Thus, rotational motion of wobble seat 136 produces linear motion of ball 138 to drive pumping mechanism 18.
First gear 78 meshes with second gear 82, which is connected to shaft 84. Shaft 84 is supported in bracket 62 by bushings 86 and 88. Gear 90 is disposed on a reduced diameter portion of shaft 84 and secured in place using bushing 92. Bushing 92 is secured to shaft 84 using a setscrew or another suitable means. Gear 90 meshes with gear 94 to rotate pin 100. Pin 100 is supported by sleeve 102 and bushing 134 in brackets 62 and 60, respectively. Gears 78, 82, 90 and 94 provide a gear reduction means that slows the input to pin 100 from the input provided by drive element 20. Depending on the type of pumping mechanism used and the type of drive element used, various sizes of gears and gear reductions can be provided as is needed to produce the desired operation of pumping mechanism 18.
As is described with respect to
Fluid pressurized in chamber 144 is pushed into pressure chamber 150 around valve stem 126 of valve 70. Valve stem 126 is biased against bracket 62 by spring 128. Seat 124 prevents fluid from passing between stem 126 and bracket 62 when stem 126 is closed. Valve stem 126 is forced away from bracket 62 as piston 72 moves toward the advanced position, as spring 120 and the pressure generated by piston 72 closes valve 68. Pressurized fluid from pumping chamber 144 fills pressure chamber 150, comprising the space between cartridge 122 and bracket 62, and pumping chamber 152. The pressurized fluid also forces piston 74 to the retracted position. Cartridge 122 reduces the volume of pressure chamber 150 such that less fluid is stored within pumping mechanism 18 and the velocity of fluid being passed through mechanism 18 is increased, which assists in clean up. The volume of pumping chamber 144 and the displacement of piston 72 is larger than the displacement of piston 74 and the volume of pumping chamber 152. As such, a single stroke of piston 72 provides enough fluid to fill pumping chamber 152 and maintain pressure chamber 150 filled with pressurized fluid. Additionally, piston 72 has a large enough volume to push pressurized fluid through outlet 154 of bracket 62. Providing suction from only a single, larger piston provides improved suction capabilities over providing suction by two smaller pistons. In other embodiments, each of pistons 72 and 74 directly draws fluid from fluid container 16 for pressurizing pressure chamber 150.
As piston 72 retreats to draw additional fluid into pumping chamber 144, piston 74 is pushed forward by an upper portion of the front surface of yoke 139 of connecting rod 96. Piston 74 is disposed within piston sleeve 108 in bracket 62, and piston seal 110 prevents pressurized fluid from escaping pumping chamber 152. Piston 74 advances to evacuate fluid pushed into pumping chamber 152 by piston 72. The fluid is pushed back into pressure chamber 150 and through outlet 154 of bracket 62. Subsequently, piston 74 retreats within pumping chamber 152 by the force of piston 72 forcing pressurized fluid back into pumping chamber 152, avoiding the need for spring return mechanisms. Piston 72 and piston 74 operate out of phase with each other. For the specific embodiment shown, piston 74 is one-hundred eighty degrees out of phase with piston 74 such that when piston 74 is at its most advanced position, piston 72 is at its most retracted position. Operating out of phase, pistons 72 and 74 operate in synch to provide a continuous flow of pressurized liquid to pressure chamber 150 while also reducing vibration in sprayer 10. Pressure chamber 150 acts as an accumulator to provide a constant flow of pressurized fluid to outlet 154 such that a continuous flow of liquid can be provided to valve 52 and spray tip assembly 14 (
Cylinder 156 of valve 52 is threaded into a socket within bracket 62 of pumping mechanism 18. Seal 168 prevents fluid from leaking between bracket 62 and cylinder 156. Spring damper 172, spring 166 and spring damper 170 are positioned around needle 164, and filter 182 is positioned around needle 164 and spring 166. Stopper 178 is inserted into axial bore 188 within cylinder 156. Needle 164 and filter 182 are inserted into cylinder 156 and needle 164 extends into axial bore 188 within cylinder 156. Seal 176 prevents fluid from leaking into the axial bore within cylinder 156. Filter 182 connects cap 158 with cylinder 156 to extend fluid passage 180 in an annular flow path toward cap 158. Cap 158 is inserted into fluid passage 180 of cylinder 156. Seal 174 prevents fluid from leaking between cylinder 156 and cap 158. Seal 162 is inserted into cap 158 to surround integrated ball tip 160 of needle 164. Connector 32 is threaded onto cylinder 156 to maintain seal 162 engaged with cap 158 and needle 164 disposed within cylinder 156.
Spray orifice 186 is inserted into bore 190 within barrel 46 of spray tip 30 and abuts shoulder 192. Seat 184 is inserted into bore 190 and maintains orifice 186 against shoulder 192. Spray tip 30 is inserted into transverse bore 194 in cap 158 such that seat 184 aligns with needle 164. Ball tip 160 is biased against seat 184 by spring 166. Seat 184 includes a contoured surface for engaging ball tip 160 such that flow of pressurized fluid is prevented from entering spray tip 30. Guard 28 is positioned around cap 158.
Upon activation of pumping mechanism 18, such as by operation of trigger 24, pressurized fluid is provided to outlet 154. Fluid from pumping mechanism 18 is pushed into valve 52 through outlet 154. The fluid travels through fluid passage 180, around filter 182, to engage cap 158. At cap 158, the pressurized fluid is able to pass between cap 158 and needle 164 at passage 196 (as shown in
In other embodiments of the invention, valve 52 may comprise an assembly in which seat 184 is integrated into cylinder 156, as is shown and discussed in the above-referenced PCT Application No. PCT/US2009/005740. For example, a pressure actuated shutoff valve may be used, such as a Cleanshot™ shutoff valve available from Graco Minnesota Inc., Minneapolis, Minn. Such valves are described in U.S. Pat. No. 7,025,087 to Weinberger et al., which is assigned to Graco Minnesota Inc. Spray tips suitable for use with the present invention include conventional spray tip designs, such as are described in U.S. Pat. No. 3,955,763 to Pyle et al., which is assigned to Graco Minnesota Inc.
Outlet stem 220 connects to sprayer 208 through spray tube 214 (
In the embodiment of
Connecting rod assembly 290 includes yoke 307, ball 308 and ball 310. Yoke 307 comprises a ring-like structure having an outer diameter surface from which balls 308 and 310 extend. Balls 308 and 310 are diametrically opposed such that they are one-hundred-eighty degrees apart on the circumference of yoke 307. Balls 308 and 310 connect to sockets 312 and 314, respectively, to couple to pistons 300 and 302. Pistons 300 and 302 are disposed within pumping chambers inside a cylinder block (not shown) along axes A2 and A3, respectively. Yoke 307 also includes an inner diameter surface in which bearing raceways for bearing sets 304 and 306 are formed. The raceways comprise shaped troughs in which ball bearings of bearing sets 304 and 306 can role.
Shaft 288 is inserted into bearing sets 304 and 306 to support connecting rod assembly 290. Hub 296 includes inner raceway troughs for ball bearings of bearing sets 304 and 306. The inner raceways are disposed on land 298 of hub 296. Land 298 is oriented along axis A4, which extends through yoke 307. Axis A4 is tilted with respect to axis A1 of shaft 288 at angle α to produce wobble effect when shaft 288 is rotated. Drive shaft 232 extends through drive block 236 along axis A5 to engage gear 228. As hub 296 rotates along axis A1, axis A4 of land 298 orbits axis A1 to cause yoke 307 to wobble. Thus, pistons 300 and 302 are reciprocated out of phase along axes A2 and A3, respectively.
Axis A1 of shaft 288, axis A2 of piston 300, axis A3 of piston 302 and axis A5 of drive shaft 232 are co-planar and parallel. In other embodiments the axes of pistons attached to yoke 307 are not co-planar with axis A1 and axis A5. For example, three pistons spaced one-hundred-twenty degrees apart along the circumference of yoke 307 may be used. Likewise, axis A5 of shaft 232 need not be in the same plane as axes A1-A3. For example, shaft 232 may be offset from shaft 288 to accommodate gear reducing mechanisms. However, for packaging, alignment, balance and vibration advantages, it is desirable to have axes A1, A2, A3 and A5 co-planar and parallel. Axis A4 of land 298 is, however, oblique and out-of-plane to the other axes in order to achieve the wobbling effect.
The wobble assemblies of the present invention transfer power from a drive element to a pumping mechanism in a compact manner to facilitate packaging in portable airless spray systems. The wobble assembly also produces efficient power transfer such that high pressures can be generated to produce highly atomized sprays. The wobble assemblies can be produced in a variety of ways utilizing a minimal number of components. Each of the components can be produced using inexpensive manufacturing processes. The components are also easily assembled. Thus, the wobble assemblies can be produced with minimal cost and time such that large-scale production of portable airless sprayers is feasible.
While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
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| PCT/US2010/001360 | 5/6/2010 | WO | 00 | 9/9/2011 |
| Publishing Document | Publishing Date | Country | Kind |
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| WO2010/129064 | 11/11/2010 | WO | A |
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| Number | Date | Country | |
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| 20120037726 A1 | Feb 2012 | US |
| Number | Date | Country | |
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| 61176194 | May 2009 | US | |
| 61107374 | Oct 2008 | US | |
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| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2009/005740 | Oct 2009 | US |
| Child | 13255768 | US |
