WO2004094070A1

WO2004094070A1 - Liquid spray gun

Info

Publication number: WO2004094070A1
Application number: PCT/US2004/005976
Authority: WO
Inventors: Joseph C. Waryu
Original assignee: Nordson Corporation
Priority date: 2003-04-15
Filing date: 2004-02-27
Publication date: 2004-11-04

Abstract

A liquid spray gun in which all wear parts, namely the armature, spring, valve needle or ball, valve seat and spray nozzle can be quickly and easily replaced with minimal interruption of a production line. A replacement parts module contains all these wear parts. The module can be quickly removed from the gun as a unit and easily replaced with a new module. The invention can be applied to an electric spray gun, in which grooves and O-rings are provided on the exterior of the module housing to provide a fluid seal between the module housing and the coil housing to which the module housing is secured. All fluid and electric lines associated with the gun are attached to the coil housing so that no lines need to be disconnected when the module is removed and replaced. Further, no individual parts, such as springs, are loose during this operation.

Description

LIQUID SPRAY GUN

Related Application

The present application claims the benefit of United States Provisional patent application serial no. 60/320,111 filed on April 15, 2003 for LIQUID SPRAY GUN, the entire disclosure of which is fully incorporated herein by reference.

Background of the Invention

The present invention relates generally to solenoid operated spray guns. In particular, the present invention relates to a spray gun for directing liquid coating material, for example, in continuous can manufacturing operations.

Liquid spray guns contain pressurized fluid and a valve which controls the spraying of the fluid from a nozzle. The valve is generally operated either pneumatically or electrically. With both types of guns, a spring normally biases the valve to the closed position. With pneumatic guns, the spring engages the backside of the piston and pressurized air acts on the front side of the piston to open the valve. With electric guns, the valve shaft includes or is attached to an armature contained within a coil. A spring normally biases the armature and valve shaft to the closed position for the valve. When the coil is energized, the armature moves against the spring to open the valve.

The principal wear parts in liquid spray guns are the valve needle or ball, the valve seat, the spring and the spray nozzle. The valve needle or ball, and the valve seat, wear out due to repeated opening and closing which can eventually cause the gun to leak. The spring wears against the chamber in which is housed causing it to abrade away and weaken over time. This changes its spring rate any thereby the speed of operation of the gun. In addition, if the spring is not periodically replaced, it will break. The spray nozzle wears out because of the spraying of fluid through it. This affects the flow rate and spray pattern from the nozzle and thereby directly affects the quality of production. Consequently, all these wear parts need to be replaced periodically.

Spray guns, particularly automatic spray guns which are fixed in position to a gun mount, as opposed to manual, or hand held, spray guns, are operated at high cycle rates with the valve opening and closing, and the spring expanding and compressing, at a high rate of speed. This produces accelerated wear of these parts. Moreover, when spray guns are used to spray cans being produced on an assembly line, for example, it is important that any maintenance be done on the guns quickly so as not to interrupt production any more than is absolutely necessary. Thus, there is always a need for spray guns on which maintenance can be done quickly and easily, with minimal interruption of the production line.

Description of the Prior Art

U.S. Patents Nos. 4,886,013; 5,296,035 and 5,941,463 all show coating systems wherein the entire spray gun is removable from a manifold to which is mounted. The fluid lines and any electric lines supplying the gun are connected to the manifold so that they do not have to be disconnected when the gun is removed. When the gun is attached to the manifold, it forms a fluid tight connection between the fluid passages in the manifold and the gun. One disadvantage of these prior art gun designs is that they require the entire gun to be replaced to change the wear parts, which means that the customer must stock entire spare spray guns as replacement parts.

U.S. Patent No. 5,078,325 shows a spray gun wherein just the ball and seat, and spray nozzle, can be easily removed and replaced. The remainder of the valve shaft, as well as the armature and spring remain in the gun. Thus, a separate operation is required to replace the spring. Replacing these separate parts is time consuming, and the production line must be shut down until the gun is fully reassembled.

U.S. Patent No. 6,182,098 shows a spray gun wherein the fluid extension, valve seat and nozzle can be removed, and thereafter the valve shaft and armature, and the spring can be separately removed. After removal, these separate parts can then be reassembled back into the gun so that the production line can be restarted. Again, maintenance of this gun is a relatively time consuming process.

Summary of the Invention

Consequently, there is a need for a liquid spray gun in which all of the wear parts, namely the spring, valve needle or ball, valve seat and spray nozzle can be quickly and easily replaced with minimal interruption of the production line. The present invention satisfies that need by providing a replacement parts module which contains all these wear parts. The replacement parts module can be quickly removed from the gun as a unit and easily replaced with a new replacement parts module, significantly reducing any production down time compared to the prior art gun designs.

In the presently preferred embodiment, the invention is applied to an electric spray gun. In an electric gun, the replacement parts module includes the spray nozzle, valve seat, valve needle or ball, valve shaft, armature and spring, with all of these elements contained within, or attached to, a module housing. In addition, in the preferred embodiment, grooves and O-rings are provided on the exterior of the housing to provide a fluid seal between the module housing and the coil housing which the replacement parts module housing is secured to.

The coil housing contains the coil as well as any fluid passages which provide for the supply of fluid to the gun or return of fluid from the gun. All fluid lines, and electric lines, associated with the gun are attached to the coil housing so that no fluid lines or electric lines need to be manually disconnected when the replacement part module is removed from the coil housing and replaced with a new replacement parts module. Further, no individual parts, such as springs, are loose during this operation.

Brief Description of the Drawings

Fig. 1 is a schematic side elevational view of a spray gun including a replacement parts module in accordance with the invention;

Fig. 2 is an enlarged schematic side elevational view of a coil housing that forms part of the spray gun of Fig. 1; and

Fig. 3 is an enlarged schematic side elevational view of a replacement parts module that forms part of the spray gun of Fig. 1.

Detailed Description of the Invention

The present invention relates generally to solenoid operated spray guns. In particular, the present invention relates to a spray gun for directing liquid coating material, for example, in continuous can manufacturing operations. The invention is applicable to spray guns of differing constructions. As representative of the invention, Fig. 1 illustrates a spray gun 10 constructed in accordance with a first embodiment of the invention. The spray gun 10 includes a first housing, or coil housing, 12. A replacement parts module 90 is removably attached to the first housing 12 and, as described below, includes the wear parts of the spray gun 10.

The coil housing 12 is attached to a gun mount 22 by one or more fasteners shown schematically at 23, which may be mounting screws, for example. The gun mount 22 is operable in a known manner to position the spray gun 10 relative to workpieces to be sprayed, for example, cans or can ends moving along a can manufacturing line for spraying the cans or can ends.

The coil housing 12 has a cup-like configuration centered on a longitudinal axis 24 of the gun 10. The coil housing 12 includes a cylindrical side wall 26 centered on the axis 24 and an annular, radially extending end wall 28. The side wall 26 and the end wall 28 define a chamber 30 in the coil housing 12. The end wall 28 has a central opening 32 that communicates with the chamber 30. The end wall 28 closes one end of the chamber -30; the opposite end of the coil housing 12 is open.

The end wall 28 of the coil housing 12 includes a plurality of fluid flow passages and ports located radially outward of the central opening 32. Specifically, the end wall 28 has an axially extending fluid inlet port 40 and an axially extending fluid outlet port 42 diametrically opposite each other. Because the inlet and outlet ports 40 and 42 are located on the coil housing 12, they are secured to the gun mount 22 by the fasteners 23. A fluid inlet line 44 is connected with the fluid inlet port 40, by a fitting such as a slip nut (not shown). A fluid outlet line 48 is connected with the fluid outlet port 42, by a fitting such as a slip nut (not shown).

A fluid inlet passage 52 in the coil housing 12 extends from the fluid inlet port 40. The fluid inlet passage 52 has an L-shaped configuration including a first section 54 that extends axially inward from the fluid inlet port 40 and a second section 56 that extends radially inward from the first section 54. The second section 56 terminates at the central opening 32 of the end wall 28.

A fluid outlet passage 60 in the coil housing 12 extends from the fluid outlet port 42. The fluid outlet passage 60 has an L-shaped configuration including a first section 62 that extends axially inward from the fluid outlet port 42 and a second section 64 that extends radially inward from the first section 62. The second section 64 of the fluid outlet passage 60 terminates at the central opening 32 of the end wall 28, diametrically opposite the second section 56 of the fluid inlet passage 52, for enabling recirculation of non-sprayed fluid, in a known manner.

The end wall 28 of the coil housing 12 also has an electrical line port 66 and a third fluid port 68. An electrical line passage 70 extends axially inward from the electrical line port 66 and terminates in the chamber 30. A sensor passage 72 extends between the third fluid port 68 and the central opening of the end wall 28. The sensor passage 72 is adapted to communicate the fluid pressure in the central opening 32 with the third fluid port 68, for pressure sensing purposes, in a known manner.

The gun 10 includes a solenoid 80. The solenoid 80 includes a coil 82. The coil 82 is located in the chamber 30 in the coil housing 12. An electrical line 84 extends from the coil 82, through the electrical passage 70 in the coil housing end wall 28, to the exterior of the coil housing. The coil 82 is supplied with electric current over the electrical line 84.

The coil 82 has a cylindrical configuration including annular, radially extending opposite end surfaces 86 and 88. The outer end surface 86 of the coil 82 is in abutting engagement with the end wall 28 of the coil housing 12. The inner end surface 88 of the coil 82 faces toward the open end of the coil housing 12. The coil 82 has a central opening 89 that aligns with the central opening 32 in the end wall 28 of the coil housing 12.

The gun includes a replacement parts module 90. The replacement parts module includes the wear parts of the spray gun 10 and is secured as one piece in the coil housing 12, for easy removal and replacement as described below. The replacement parts module 90 that is shown and described herein has one particular configuration and includes one particular set of parts, including wear parts. Replacement parts modules in accordance with the invention, used with different guns, could have different configurations and different sets of parts, including wear parts.

The replacement parts module 90 includes a main body, or module housing, 92. The module housing 92 has three portions: a main body portion 94, a fluid inlet portion 96 that extends in one direction from the main body portion, and a fluid outlet portion 98 that extends in the opposite direction from the main body portion.

The fluid inlet portion 96 of the module housing 92 has a narrow cylindrical configuration adapted to fit through the central opening 89 in the coil 82 and through the central opening 32 in the end wall 28 of the coil housing 12. The fluid inlet portion 96 of the module housing 92 has a central fluid passageway 100 that extends also into the main body portion 93 and the outlet portion 98 of the module housing 92.

Several grooves are provided on the exterior of the inlet portion 96 and communicate with the central passageway 100 in the module housing 90. A groove 102 aligns with and communicates with the fluid inlet passage 52 and the fluid outlet passage 60 in the coil housing 12, for directing fluid into the central passageway 100 of the module housing 92, when the module 90 is in the coil housing 12. As a result, fluid flowing into the gun 10 from the fluid inlet port 40 can pass into the central passageway 100 of the module housing 90. Another groove 104 aligns with and communicates with the pressure sensor passage 72 in the coil housing 12. Three O-rings 106 on the fluid inlet portion 96 of the module housing 92 provide a fluid seal between the replacement parts module 90 and the coil housing 12.

An armature 110 is located in the fluid passageway 100 of the module housing 90. The armature 110 is supported in the fluid passageway 100 for reciprocating movement under the influence of magnetic fields generated by the coil 82. A compression spring 112 is also located in the fluid passageway 100 of the module housing 90. The spring 112 acts between the armature 110 and the module housing 90 to bias the armature in a direction away from the end wall 28 of the coil housing 12, that is, downward as viewed in Figs. 1-3. A valve shaft or needle 114 is also located in the fluid passageway 100. The needle 114 is reciprocable in the fluid passageway 100 in response to movement of the armature 110 by the coil 82. The needle 114 may be formed as one piece with the armature 110, or may be a separate piece that is movable in response to movement of the armature. The needle 114 extends through the main body portion 92 of the module housing 90 and through the outlet portion 96 of the module housing. A ball or other type of movable valve member 116 is fixed on the end of the needle 114.

The outlet portion of the module housing supports a valve 118 and a spray nozzle 120. The valve 118 includes, in addition to the ball 116, a valve seat 122. The valve seat 122 is engageable by the ball 116 when the needle 114 is in the closed position. When the coil 82 of the solenoid 80 is electrically actuated, the armature 110 moves in the module housing 90, and moves the needle 114 in a direction to move the ball 116 off the seat 122 (upward as viewed in Fig. 3), against the bias of the spring 112, allowing fluid to flow out of the gun 10 through the valve 118 and the spray nozzle 120. When the coil 82 is de-energized, the spring 112 moves the armature 110 and the needle 114 back to the starting position, and the ball 116 engages the seat 122, to block fluid flow out of the valve 118 and the nozzle 120.

Thus, the replacement parts module 90 includes all the wear parts of the spray gun 10— the ball 116 and seat 122, the armature 110, the needle 114, and the spring 112. All these parts are fixed in or on the module housing 90, and are movable with the module housing, as one unit, when the module housing is moved relative to the coil housing 12~that is, connected to or disconnected from the coil housing, as described below.

The replacement parts module 90 is secured as one unit to the coil housing 12, for easy removal and replacement. The gun 10 includes two module lock screws 130. The screws 130 are preferably socket head screws. When the replacement parts module 90 is connected with the coil housing 12, as shown in Fig. 1, the main body portion 93 of the module housing 92 is located in the chamber 30 of the coil housing 12. The side wall 26 of the coil housing 12 extends around the main body portion 93 of the module housing 92. The module lock screws 130 extend through radially extending clearance holes 132 in the coil housing side wall 26, adjacent the open end of the coil housing 12. The module lock screws 132 are screwed into tapped holes 134 in the main body portion 93 of the module housing 92.

To remove the module housing 92 from the coil housing 12, the valve 118 is first closed, by controlling the flow of electric current to the coil 82 of the solenoid 80, thereby moving the valve ball 116 against the valve seat 122. Fluid pressure is then removed from the spray gun 10 by closing a valve or other fitting, shown schematically at 136, that controls fluid flow through the fluid inlet line 44.

The module lock screws 130 are loosened (unscrewed) sufficiently that they come out of the tapped openings 134 in the module housing 92. When this occurs, the module housing 90 including its attached and enclosed parts can be removed from the coil housing 12, without any tools, simply by pulling it out axially.

When the replacement parts module 90 is thus removed from the coil housing 12, no fluid or electrical lines need to be disconnected. The fluid inlet line 44 and the fluid outlet line 48 remain attached to the coil housing end wall 28. The electrical line 84 remains attached to the coil 82, which remains in the chamber in the coil housing 12. The fluid inlet valve 136 to the gun 12 needs to be closed, but the fluid inlet line 44 does not need to be disconnected. The spring 112 of the module 90 remains enclosed within the module housing 92 and is loose.

To reinstall or attach the replacement parts module 90, or to install another replacement parts module, the inlet portion 94 of the module housing 92 is inserted through the central opening 89 in the coil 82 and into the central opening 32 in the end wall 28 of the coil housing 12. The main body portion 93 of the module housing 90 engages the outer end surface 88 of the coil 82. When this engagement occurs, the through holes 132 in the coil housing side wall 26 are aligned with the tapped openings 134 in the main body portion 93 of the module housing 92. The module lock screws 130 can then be inserted through the through holes 132 in the coil housing side wall 26, and screwed into the tapped openings 134 in the main body portion 93 of the module housing 92. The replacement parts module 90 is thus secured in the coil housing 12.

Fluid pressure to the gun 10 can then be applied by opening the valve 136 in fluid inlet line 44 and, when the gun is to be operated, the valve 118 is opened to enable fluid to be sprayed from the nozzle 120.

From the above description of a preferred embodiment of the invention those of ordinary skill in the art will appreciate that the teachings of the invention can be applied to other spray guns of differing constructions, and that the spray gun described above is only an example used to demonstrate the teachings of the invention. For example, the replacement parts module can be secured to the coil housing using only one module lock screw rather than two, or with a type of fastener other than a screw. The module lock screw or other fastener can be tethered or otherwise connected with the coil housing so that it does not come completely loose when the module is being replaced. Accordingly, while various modifications to the invention will be apparent to those of ordinary skill in the art, such modifications are intended to be included within the scope of the appended claims.

Claims

Having described the invention, I claim:

1. A spray gun comprising a first housing and a second housing, the second housing comprising a replacement parts module, the second housing being removably attached to the first housing.

2. The spray gun of claim 1 wherein fluid lines are connected to fluid passages in the first housing, and wherein the replacement parts module includes fluid passages, the fluid passages in the first housing being connected to the fluid passages in the replacement parts module when the replacement parts module is attached to the first housing.

3. The spray gun of claim 1 wherein the replacement parts module includes a spring.

4. The spray gun of claim 3 wherein the first housing includes a coil, and wherein the replacement parts module includes an armature.

5. The spray gun of claim 4 wherein the replacement parts module includes a valve shaft comiected to the armature.

6. The spray gun of claim 5 wherein the valve shaft has a valve end which engages a valve seat.

7. The spray gun of claim 1 wherein the valve seat is part of the replacement parts module.

8. The spray gun of claim 6 wherein the valve seat is part of the replacement parts module.

9. The spray gun of claim 1 wherein the replacement parts module includes a spray nozzle.

10. The spray gun of claim 8 wherein the replacement parts module includes a spray nozzle.

11. The spray gun of claim 2 wherem O-rings are provided on the replacement parts module to provide a fluid seal between the replacement parts module and the first housing.

12. The spray gun of claim 1 wherein fasteners are used to attach the replacement parts module to the first housing.

13. The spray gun of claim 5 wherein the replacement parts module has a fluid passageway and wherein the spring, armature and valve shaft are contained within the fluid passageway.

14. A method for maintaining a liquid spray gun that includes a first housing and a second housing, wherein the first housing is secured to a fixed mount and wherein the second housing comprises a first replacement parts module which includes a spring and a valve, the valve including a valve end and a valve seat, the method comprising the steps of: a. closing the valve end against the valve seat; b. removing fluid pressure from the liquid spray gun; c. removing the first replacement parts module from the first housing; d. attaching a second replacement parts module to the first housing; e. applying fluid pressure to the liquid spray gun; and f. opening the valve of the second replacement parts module.

15. A method as set forth in claim 14 wherein said step of removing the first replacement parts module from the first housing comprises removing a module containing a spring and an armature.

16. A method as set forth in claim 15 wherein said step of removing the first replacement parts module from the first housing comprises removing a module containing a valve shaft and a valve seat.

17. A method as set forth in claim 16 wherein said step of removing the first replacement parts module from the first housing comprises removing a module containing a spray nozzle.

18. A method as set forth in claim 14 wherein said step of attaching a second replacement parts module comprises providing a fluid seal between the second replacement pars module and the first housing with O-rings on the second replacement parts module.

19. A method as set forth in claim 14 wherein said step of removing fluid pressure from the liquid spray gun is preformed without disconnecting any fluid lines from the liquid spray gun.

20. A spray gun for a fluid coating system and for spraying fluid, said spray gun comprising: a housing for supporting said spray gun, said housing having a fluid inlet port to which a fluid inlet line can be connected and disconnected, said housing also having a portion for receiving an electrical line; said housing defining a chamber in said housing, said chamber having a longitudinal axis; a coil in said housing that is electrically energizable by an electric current over the electrical line; and a module that can be selectively connected with said housing, said module including a core, an armature slidable in said core, a spring biasing said armature, a nozzle, a fixed valve member, and a movable valve member movable in response to movement of said armature.

21. A spray gun as set forth in claim 20 wherein said module is removable from said housing without disconnection of the fluid inlet line from said fluid inlet port of said housing.

22. A spray gun as set forth in claim 21 wherein said housing further includes a fluid outlet port, a first fluid flow passage in said housing communicating between said fluid inlet port and said chamber, and a second fluid flow passage in said housing communicating between said chamber and said fluid outlet port.

23. A spray gun as set forth in claim 22 wherein said one of said first and second fluid flow passages in said housing has an L-shaped configuration including a portion extending generally parallel to said longitudinal axis and a portion extending generally perpendicular to said longitudinal axis, and wherein said module includes a fluid inlet opening and a fluid outlet opening both extending generally perpendicular to said longitudinal axis.

24. A spray gun as set forth in claim 20 including at least one module lock screw that is extensible through a clearance openings in said housing into a tapped hole in said module to secure said module in said housing.

25. A spray gun as set forth in claim 24 wherein said module lock screw is rotatable in said tapped hole about a screw axis that extends generally perpendicular to said longitudinal axis of said chamber.

26. A spray gun as set forth in claim 20 wherein said module is supplied with fluid to be sprayed through one or more fluid inlet openings in said module that extend radially to said longitudinal axis and that communicate with one or more fluid passages in said housing.

27. A replaceable module for connection with a housing of a liquid spray gun, comprising: a module housing; fluid passages in the module housing; a spring in the module housing; and an armature in the module housing.

28. A replaceable module as set forth in claim 27 further including a valve shaft connected to the armature.

29. A replaceable module as set forth in claim 28 wherein the valve shaft has a valve end which engages a valve seat.

30. A replaceable module as set forth in claim 29 wherein the valve seat is part of the replacement parts module.

31. A replaceable module as set forth in claim 27 wherein the replacement parts module includes a spray nozzle.

32. A replaceable module as set forth in claim 27 wherein a valve shaft and a valve seat are part of the replacement parts module.

33. A replaceable module as set forth in claim 32 wherein the replacement parts module includes a spray nozzle.

34. A replaceable module as set forth in claim 27 wherein O-rings are provided on the module to provide a fluid seal between the module and the housing of the spray gun.

35. A replaceable module as set forth in claim 27 wherein at least one fastener is used to attach the module to the spray gun housing.

36. A replaceable module as set forth in claim 27 having a fluid passageway and wherein the spring, the armature and a valve shaft are contained within the fluid passageway.