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Publication numberUS3450092 A
Publication typeGrant
Publication dateJun 17, 1969
Filing dateJul 8, 1965
Priority dateJul 8, 1965
Also published asDE1577696A1, DE1577696B2, DE1577696C3
Publication numberUS 3450092 A, US 3450092A, US-A-3450092, US3450092 A, US3450092A
InventorsKock Erhard
Original AssigneeVilbiss Co The De
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Color change apparatus
US 3450092 A
Abstract  available in
Images(3)
Previous page
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Claims  available in
Description  (OCR text may contain errors)

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E R was SQN %N 553 )QQWQ WSQIL I NI I I I! IIIIIIIIIIII I I. I I II w A m m K D m H R E ilnited States Patent C) 3,450,092 COLOR CHANGE APPARATUS Erhard Keck, Toledo, Ohio, assignor to The De Vilbiss Company, Toledo, Ohio, a corporation of Ohio Filed July 8, 1965, Ser. No. 470,497 Int. Cl. B05c 11/00 U.S. Cl. 118-2 15 Claims ABSTRACT OF THE DISCLOSURE An apparatus including a spray gun for selectively depositing one of a plurality of fluid coating materials upon objects to be coated. The apparatus includes a pneumatically controlled pressure regulator elfective to provide a relatively low fluid pressure for the coating materials and pneumatic control means to override the pressure regulator to cause a relatively high fluid pressure when a solvent is used to purge the system prior to change from one of said materials to another.

This invention relates to an apparatus for controlling a spray device to facilitate deposition of coating materials of varying kind. More particularly, the invention is concerned with an apparatus that will enable a spraying device to sequentially discharge differently colored liquid coating materials. However, the invention is equally appli cable to instances in which the difference between successively sprayed coating materials is one of another nature such as a diflerence in viscosity. The invention is also useful where it is desired momentarily to increase the pain discharge as, for example, to clear a partially clogged spray gun.

At the present time the spraying of various colors of paints or the like is done largely with separate spray guns, one for each color, or with one gun that is adapted for rapid connection and disconnection to hoses carrying separate colors of paint. Attempts have been made to pro vide a remotely controlled apparatus which will feed separate colors to a single spray gun and which will also permit the operator to clean the spray gun by passing a solvent through it as a part of the color change cycle. The patents to Fleming, 2,257,004, and Herklotz et al., 3,145,930, show apparatus of this general class.

It is desirable that a color change apparatus be fast enough to complete a color change in the interval between the passage of successive articles to be sprayed which are hung on a conveyor traveling at a normal speed. This time interval may amount to only a few seconds. Further, the apparatus must require a minimum of judgment and dexterity on the part of the operator so that mistakes can be avoided, as far as possible, to eliminate improperly sprayed parts. Not only must the color change apparatus operate rapidly, but it must also be flexible enough to take into account the various problems that arise by reason of the change in characteristics of successively sprayed materials.

An apparatus which uses a single gun for spraying a plurality of colors or kinds of liquids usually requires a flushing period during which the remaining residue of the terminated liquid is purged from the common gun by a solvent prior to initiation of spraying the second liquid. However, it has been found that under many conditions this quantity of terminated liquid is so small that only a very short purge is required.

The change of color, even when including a solvent purge, can be made more rapidly if provision is made for increasing the pressure on the sprayed liquid during the time in which the conduit to the spray gun is being flushed and filled with the new color. This is accomplished in the apparatus disclosed in the Herklotz et al. patent referred to above by increasing the speed of rotation of a centrifugal paint supply pump during the color change and dropping the speed back to normal when the change is complete. In most installations in this country, the use a mechanically driven metering type paint supply pump is avoided, and paint is fed to the spray gun from a pressure pot in which the paint or liquid coating material is held under a predetermined pressure imposed by pressurizing the air in the paint container or from a paint circulating system in which a constant pressure is held on the paint. The present invention is adapted to a substantially constant pressure paint supply system.

In the following description and discussion the word fluid is used to designate a liquid coating or flushing material, and the word air is used whenever a gaseous medium is referred to.

In accordance with the present invention, the pressure at which fluid passes to and out of the spray gun is controlled by an easily controllable air pressure. As the air pressure is increased, the fluid pressure is likewise increased automatically.

While spraying proceeds normally with the fluid coating material supplied to the spray gun at a predetermined low pressure of, for example, 5 to 7 p.s.i., a fluid pressure regulator valve at the spray gun receives control air at this pressure from a control regulator. When the color change is to be made, or the system is to be flushed, the present invention includes a fluid pressure control override by which the control air is caused to pass to the fluid regulator at the spray gun under a substantially increased pressure of, for example, 25 to 30 p.s.i. The increase in pressure on the fluid regulator valve permits fluid at a correspondingly increased pressure to pass through the fluid conduits and out of the spray gun from the pressurized sources above mentioned..It will be seen that so long as the source pressure is maintained above any pressure that might be desirably used at the spray gun, pressure fluctuation at this point will not afl ect the system in any way since reguation takes place at the regulator valve which is normally very close to the spray gun itself.

If the spraying system is to be used with the customary volatile and flammable solvents, it becomes desirable to eliminate from the spray zone or spray booth, so far as possible, all electrical relays, switches and other devices in which sparking may occur. To comply with safety requirements any such devices located in the spray Zone must be of an approved explosive-proof construction and requires special installation. To avoid this significant increase in the expense of an installation, the present invention utilizes pneumatically actuated valves and controls throughout the spray zone and is thus economical. In some installations, remotely located electrical devices may be tolerated so long as they are not in or near the spray booth or spray zone where a mist of flammable liquid may be found.

As previously noted, it is desirable that the system be so arranged that the flow of solvent or flushing fluid be started promptly after the termination of the flow of the existing color at the commencement of a color change cycle. It is, of course, imperative that there be no possibility of intermingling colors inadvertently.

The present invention provides a related group of color and solvent control air valves in series and so disposed that when, and only when, all of the color valves are closed, air will be supplied to the solvent control valve, causing solvent to enter the feed line to the spray gun. When the opertor determines that the feed line has been completely flushed, as by visual observation or by the lapse of suflicient time, he then opens the control air valve for the selected new color. This manipulation by itself will cut off the supply of air to the solvent control air valve because of the serial relation between the valves, and the flow of solvent to the gun will stop and will be replaced by the flow of coating material fluid of the new color. The present invention provides, as an option, that the high pressure under which flushing takes place will persist for a few seconds after the flow of the new color fluid commences so that the fluid conduits to the spray gun will be filled rapidly with the new color fluid.

In one modification of the invention the cleaning and refilling of the system up to the spray gun is accomplished with the spray gun closed, and the cleaning fluid passes out to a waste tank. In this arrangement the small fluid passage in the gun itself will retain some fluid of the color to be replaced. This fluid is flushed out very quickly by the solvent remaining in the lines and by the new color when the gun is reopened. The capacity of the gun fluid passage may amount to only 1 cc. or 2 cc. and if the normal discharge rate of the spray gun is 150 cc. per minute, it can be seen that replacement of the old color by the new will not cause a significant time delay. This puff of fluid at the end of the color change cycle in most cases can be directed between successive parts on a conveyor line without depositing on the conveyed articles on either side.

The principal object of the invention is to provide an apparatus having the functional features discussed above.

Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment thereof, reference being made to the accompanying drawings, in which:

FIGURE 1 shows a color change spray apparatus of this invention adapted for spraying three separate fluids, such as paints A and B and a solvent, through a single common spray gun, with the air, fluid and electrical control systems schematically illustrated. In this modification the spray gun is held open during a color change;

FIG. 2 shows diagrammatically an apparatus similar to FIG. 1, but in which the spray gun is held closed during a color change; and

FIGURE 3 shows diagrammatically an apparatus similar to FIG. 2, but embodying additional operating devices to improve performance under certain conditions.

The diagrammatic representation of on-off air valves used in the drawings is such that the normal connections through the valve body are indicated by full lines, while the alternate connections that are established by movement of the valve to its opposite position are indicated by dotted lines. Where a valve is normally operated manually, a push-pull button is indicated as connected to the movable valve elements. Where a valve is normally operated by a solenoid, the armature of the solenoid is indicated as being directly connected to the movable valve parts. In those instances in which the valve is shifted by a separate pneumatic cylinder the associated piston and movable valve parts are shown as connected directly. These diagrammatic notations are used solely for simplification and are not intended to indicate the actual valve structures, or the structures of the activating means, which may be quite complex.

In the drawing a typical automatic spray gun is shown at 10 and includes a pneumatic cylinder 11 at the rear of the gun body having a piston 12 the-rein which is directly connected to a fluid needle 13 of the spray gun. The needle 13 operates as a valve to open or close a central fluid discharge passage 14 through which coating material is emitted for atomization. In the spray gun 10 atomizing air enters the gun body from a passage 15 and discharges from an annular orifice 15a immediately around the fluid orifice in the cap portion of the spray gun. The atomizing air is cont-rolled by an air valve 16 that is diagrammatically indicated as being carried by the fluid needle 13 and thus moved off its seat by the piston 12 when the gun is turned on.

Fluid is supplied to the central fluid passage 14 of the spray gun through a conduit 17 and is held at a regulated pressure by a fluid regulating valve 18. During normal spraying, the fluid pressure is maintained at a relatively low pressure, for example, 5 to 7 p.s.i. by control air pressure from another control regulator valve 19. The regulator valve 18 is such that its discharge pressure is a direct function of the control air pressure imposed on its internal diaphragm by control regulator 19. Regulator 19 is manually adjustable so that the operator can vary the normal fluid pressure at will.

The present invention is applicable to electrostatic or non-electrostatic spray guns, but the invention is shown in connection with an electrostatic spray gun 10 supplied with high voltage from a high voltage power supply 20 connected to a suitable electrical source 21. As is the usual practice, one side of the high voltage power supply is grounded and the other side is taken to the gun through a high voltage line 22. A high voltage switch 23 is interposed in the line 22 and is normally held closed but may be opened when the holding air pressure is released.

In the diagrammatic system shown in the drawings the high voltage switch 23 may be opened by movement of an air actuated cylinder 24 having its plunger connected to a valve 25 such that movement of the plunger of the air cylinder 24 to the right, as shown, will cause the valve 25 to vent the air cylinder of the high voltage switch 23, causing this switch 23 to open by its spring pressure. The air cylinder 24 is in turn controlled by a solenoid operated valve 26 which is normally in the upper or vented position as shown. When the circuit to the winding 27 of the solenoid operated valve 26 is energized, through closure of a normally open switch 28 controlled by an air cylinder 28a, the force of the solenoid 27 will pull the valve 26 closed, thus admitting air at high pressure from a supply line 29 which will open the switch 23 and break the circuit to the high voltage line 22 and to the gun 10.

Air for the various control functions hereinafter described is taken from a regulated source 30. The regulation may be such as to cause air to enter the system at 60 p.s.i., in line 29, for example. From line 29, one branch line for the atomizing air connects, through a reducing valve 31, to the atomizing air valve 16 within the gun 10 through line 15. The reducing valve 31 is effective to reduce the air pressure from the line 29 to a low value for atomization, such as 7-10 p.s.i.

The spray gun is supplied with fluid from several sources, A, B, C, by any suitable means. In the diagrammatic disclosure, the contents of the containers A, B, C, are placed under air pressure from source 30 through a branch line of the air supply line 29. The discharge from each of the several fluid containers A, B, C, goes respectively to a pneumatically controlled valve 32A, 32B, 32C and thence into a common manifold 33 to the fluid pressure regulator 18 adjacent the spray gun 10. This fluid regulator 18 normally permits fluid to flow to the spray gun 10 at a reduced pressure of, for example, 5 to 7 p.s.i. because of the normal, low pressure air imposed thereon by the adjustable air regulator valve 19.

Each of the pneumatically actuated valves 32A, 32B and 32C has a respective power cylinder 34, 35 and 36 to which air is admitted or exhausted from a respective connector line 37, 38, 39. Air to these connector lines 3739 is controlled by manually operated color control valves 40, 41, 42 respectively.

It will be seen that in the on or full line position (FIG. 1), the valve 40 is connected such that air will flow from supply line 29, through a branch line 43, the valve 40, the connecting line 37, and the power cylinder 34 for the respective needle valve 32A, which is then opened. Fluid from container A will thus be pushed by air pressure from line 29 through a feed line 44 through the open valve 32A into the paint manifold 33 to the fluid regulator valve 18 adjacent the spray gun 10, through the passage 17 between the regulator valve 18 and the paint discharge passage 14 within the gun.

It will be seen that when the paint A valve 40 is in its open position, no air can pass beyond this valve to either valve 41 or 42 above it in the series. Further, it will be seen that the valve 41 or 42 can receive air only when all valves beneath them in the series are in the closed position. Thus it becomes impossible to charge two colors simultaneously into the manifold 33 because only one of the power cylinders 34-36 can be actuated to open the corresponding valve 32A-32C at one time.

In normal operation when the apparatus is spraying a single fluid upon objects 45 sequentially presented to the spray gun on a moving conveyor, a control circuit including a photoelectric cell circuit 46, a solenoid operated air valve 47, and an air valve 48 are operably connected to the piston 12 and fluid needle 13 of the spray gun 10 to periodically block the flow of fluid and air from the gun 10 when no object 45 is before the gun pattern. The photoelectric cell circuit 46 is electrically connected to the electrical source 21 by leads 49 and 50 and is positioned in the vicinity of the conveyor such that it is energized by the presence of an object 45 (schematically shown in the drawings), when the object 45 or another such object is in the proper position on the conveyor, within the pattern of the spray gun 10. The output from the energized photoelectric cell circuit 46 is connected to the winding 51 of the solenoid operated air valve 47. When energized, the winding 51 closes the air valve 47 to its lower, dotted line position whereby air at 60 p.s.i. flows from the supply line 29, through a branch line 52, the valve 47 and into the cylinder of the air valve 48, causing its piston and plunger to close this valve to its upper, dotted line position. When the valve 48 is so closed, air at 60 p.s.i. flows through the valve 48, a branch line 53 to the air cylinder 11 in the gun 10, causing the piston 12 to withdraw and admit atomizing air to the gun and to open the discharge passage 14 thereof. As soon as the object 45 has passed the photoelectric cell, the revenue sequence takes place and the gun 10 ceases to spray until another such object 45 is in the range of the pattern of the gun 10.

A bypass circuit, which may be operated manually or automatically, is provided, which may be used to keep the operating piston 12 of the gun 10 retracted, if desired, regardless of the condition of the photoelectric cell circuit 46 and the pressure or absence of an article 45 to be sprayed. As indicated diagrammatically in the drawings, a manually operated air valve 54 is connected through line 55 to the lower port of the air valve 48 as shown. When the valve 54 is manually opened to its lower, dotted line position, air at 60 p.s.i. bypasses the solenoid operated valve 47 and flows through the line 55, valve 48, and line 53 to the air cylinder 11 of the gun 10.

An important feature of the color change apparatus of this invention is the system including the air operated switch 28, solenoid operated air valve 26, the air operated voltage control valve 25 and an air operated override air valve 56. The system including these components comprises a means for overcoming the normal adjustment of regulator valves 18 and 19 whereby fluid such as the solvent fluid from container C may be pushed through the control valve 32C, the manifold 33, the regulator 18, the line 17 and into the gun 10 at an increased pressure and velocity, thus reducing the time necessary for purging these lines of the terminated fluid, paint A for example, prior to the initiation of spraying a second fluid, paint B for example.

The air cylinder portion 28a of the air operated switch 28 is connected to the outlet side of the manual color control valve 42 by a line 58 whereby air pressure in the line 58 will push the piston of the air cylinder 28a to its upper, dotted line position and will close a pair of normally open contacts 59 to complete an electrical circuit from the power source 21 to the solenoid winding 27. As previously explained, no air can flow to the manual solvent control valve 42 controlling the flow of solvent until both manual paint control valves 40 and 41 are closed. To terminate flow of a fluid such as paints A or B and to initiate the accelerated purge cycle, the operator closes valve 40 or 41 and thus permits air to flow through the valve 42, thus admitting air at 60 p.s.i. to the line 58 and closing the electrical circuit to the winding 27. The air valve 26, after the winding 27 is energized, is pulled to its lower (dotted line) position so that air flows through the valve 26 to lines 60 and 61 and to the air cylinder 24 of valve 25. The following steps then occur simultaneously:

(1) Air in the line 61 forces the piston of an air cylinder 62 downwardly, thus closing a normally open switch 63 to complete an electrical circuit to the winding 51. This circuit, which is in parallel with the circuit of the photoelectric cell 46, acts as a bypass to the photoelectric cell circuit 46 and, in the manner previously explained, causes the gun 10 to remain on, or to be turned on regardless of the presence or absence of an object 45 sensed by the photoelectric cell circuit 46. The elfective disabling of the photoelectric cell circuit 46 is necessary because, in this modification of the invention, it is desirable to complete the solvent purge from the gun 10 when no objects 45 are in front of the gun and with the gun 10 open.

(2) Movement of the piston of the air valve 24 to its right, dotted line position by air pressure from the valve 26 will move the valve 25 to the right to vent the air cylinder controlling the high voltage switch 23, causing the switch 23 to open and to break the high voltage charging circuit to the gun 10. This is desirable during the solvent purge period to prevent the charged particles from leaving the spray path and being deposited on the grounded workpiece or grounded portions of spraying apparatus. If desired a conventional grounded back contact can be placed on switch 23 to ground the gun during the time switch 23 is open.

(3) Air pressure in the line 60 operates the fluid override by moving the piston in the air cylinder of the override valve 56 to the right, thus connecting the valve 56 to a line 64 with air at an intermediate pressure (30 p.s.i.), maintained by a regulator valve 65 from the line 29. This air, passing under intermediate pressure to a line 66 through a manually operated two-way bypass valve 57 which is normally in its solid line, right hand position, enters the regulator valve 19 and opens the regulator valve 19, thus allowing control air at increased pressure to flow from the line 29, through a branch line 67, through the regulator valve 19 and a line 68 to the fluid pressure regulator valve 18 at or near the gun 10. The regulator valve 18 is in turn opened, whereby the fluid from the container C will flow through the control valve 32C, the manifold 33, the regulator valve 18, the line 17 into the gun 10 at increased pressure. By overriding the regulator valve 18, the solvent purge takes place at increased pressure and thus a much shorter time is required to purge the manifold 33 and subsequent lines of the terminated fluid.

From the foregoing it will be seen that the flow of solvent through the manifold 33 and to the spray gun -10 will continue until such time as the operator initiates the flow of the new color paint by pulling an appropriate paint control valve 40 or 41.

When purging of the system is completed, it is usually desirable to delay the inactivation of the override system for a short time after the initiation of a new color cycle in order to permit the system to be filled at high pressure and to clear the system of the purging liquid. This delay is provided by any suitable device such as an electric time delay switch 72 connected in parallel across the contacts 59 of the air operated switch 28. When the operator initiates the flow of the new fluid by closing the manual change valve 41, for example, the simultaneous venting of the line 58 causes the solvent control valve 32C to close and also opens the contacts 59 of the air operated switch 28. The time delay device 72, however, will keep the circuit to the solenoid 27 closed for a predetermined time after the switch contacts 59 are opened. Therefore, the override system will continue to operate and paint from the control valve 32B will be forced through the manifold 33 and subsequent lines at high pressure until the time delay device 72 opens the circuit to the solenoid 27. Thus, in addition to the accelerated purging cycle described, the system also includes an accelerated refill cycle to reduce the time necessary for changing from one color to another. Also, the spray gun 10 remains open and the voltage remains off due to the continued presence of pressurized air in line 60.

From the foregoing, it will be understood that the flow of solvent through the system will continue for an indefinite period of time and that its termination is, in the form shown, manually controlled. It is, of course, desirable that the operator not terminate the flow of solvent and the initiation of the new paint color too quickly. Therefore, the present invention provides an indicator that will alert the operator to the passage of a minimum time during which the flow of solvent should persist. In the form shown, the indicator is designated by the numeral 70 and an interval timer 71 is actuated pneumatically by a branch connection to line 58. The time interval begins to time out with the entry of air into line 58 at the beginning of the purge cycle. At the end of the timed interval, a valve 73 is shifted from vent position to a connected position in which air enters from the main source line 29 to a cylinder 74. A piston 76 is actuated thereby and in turn actuates the indicator 70 which may be either in the form of a flag, a light, or any other alerting device. The interval timer 71 is automatically reset when line 58 is vented at the end of the solvent cycle.

When the time delay device 72 times out, and the circuit around contacts 59 is finally opened, the system will be'filled with paint of the new color and will be ready to spray under normal pressure. The solenoid controlled valve 26 will have returned to its normal, or vented position shown in dotted lines in FIG. 1 and the air pressure will have been removed from the air cylinder 24, allowing the voltage control valve 25 to move to its open position in which air passes from line 29 to the air operated high voltage switch 23. As switch 23 closes, the voltage is restored to the spray gun, and normal electrostatic spraying will proceed thereafter. At the same time, the air actuated automatic override valve 56 will move to its normal or vent position and the override pressure will be removed from line 66, allowing the air pressure control regulator 19 to return to its pre-set pressure. The normal regulator pressure will then be restored in the fluid regulator 18, and the fluid pressure in line 17 leading to the spray gun will be within the normal range for satisfactory spraying. Thereafter the on-oif control of the spray gun will revert to the automatic system including, for example, the photoelectric control circuit 46.

As it has been so far described, the present invention provides for the introduction of air into the fluid override line 66 automatically, and only during a color change cycle. However, the present invention is equally useful at any other time when it is only necessary to temporarily increase the pressure at which fluid is passed to the spray gun 10. In some instances, after prolonged operation, a spray gun 10 will exhibit a tendency to clog or emit its spray in a pattern that is not perfectly distributed. Under these circumstances, operation of the gun 10 even momentarily at a greatly increased pressure will frequently clear the system and cause it to return to normal operation. The present invention provides, for this purpose, the manually operated bypass valve 57 for the fluid override air. The valve 57 in its normal position is in series with the automatic override valve 56. When the valve 57 is manually pulled from its full line to its dotted line position as shown in FIGURE 1, the series relationship to valve 56 is broken and a connection is established by which air will pass from line 64 to the override air line 66. This will increase the control air pressure on regulator 19 and thus 0n the fluid pressure regulator valve 18, causing the system to be filled with fluid of the same type as is then being sprayed, but at much higher pressure. This will permit the operator to clear the gun or guns. The same manual control of the override air provided by valve 57 also makes it possible to change from one color to another directly at any time without going through the solvent purging of the system by allowing a new color paint to displace a previous one at high pressure.

The modification of the invention shown in FIGURE 2 of the drawings differs from the modification previously described in that the color change or purging takes place with the spray gun 10 closed, rather than open. In reference to this modification, the same numerals have been used to indicate parts of the system that are identical to the parts previously described and shown in FIGURE 1. The modification may, if desired, eliminate the bypass for the photoelectric control circuit 46 comprising air line 61 and the air operated switch 63. Thus, when the spray gun 10 is shut off in response to operation of the photoelectric control circuit 46, it will remain off until this circuit 46 causes it to reopen.

A T-connection 76 is made to fluid line 17 at the point where it enters the body of the spray gun 10 to connect into the interior fluid passage 14. In the most simple form of this modification a fluid dump valve in the form of a check valve 77 is inserted in the line leading from the T-connection 76 and the outlet from the check valve 77 is taken to any suitable container, which is indicated as a waste drum W.

The check valve 77 is pre-set to open at a pressure in excess of the normal pressure existing in line 17 during normal spraying. For example, if the upper range of the normal fluid pressure in line 17 is 7 pounds, then check valve 77 can be set to open in the direction of the waste container at a pressure of 9 to 12 pounds. During the override cycle, while a color change is being made, fluid flows through line 17 at an increased pressure and will thus pass out through the check valve 77 since the spray gun 10 is now closed. All of the lines between line 17 and the manifold 33, including the regulator valve 18, will be purged and cleaned and the purging and cleaning fluid will pass out past check valve 77 to the container W. This will leave only the small quantity of fluid trapped in the fluid passage 14 of the color that is being displaced. The capacity of this interior passage 14 in the gun will usually amount to only 1 cc. or 2 cc. This small quantity of retained fluid is readily displaced by any solvent remaining in line 17 and displaced by the next successive color.

If desired, provision can be made for opening the spray gun 10 in advance of the time when the next part will be presented to the spray gun 10, or the automatic control comprising the photoelectric circuit 46 may simply be relied upon to cause the gun 10 to reopen. The small puff of paint of the previous color can frequently be accepted on the new part presented to the spray gun 10 without deteriorating the finish of the new part in any way. However, if it is felt that no paint whatever of the old color should be sprayed on the new part, then the spray gun 10 should be opened in advance of the time when it would be normally opened by the photoelectric control circuit 46 and the puff of paint dispersed in the space between parts on the conveyor.

In the sequence of operations of the apparatus shown in FIG. 2, let it be assumed that the spray gun 10 is spraying paint on a part 45 from the container containing paint A at normal spraying pressures, through valve 32a as controlled by air valve 40. Under these circumstances,

9 the fluid pressure in line 17 will be from S to 7 p.s.i. and the air pressure in control line 68 will be the normal pressure required to maintain the above-mentioned fluid pressure to the gun 10. When a color change cycle is to be initiated, the gun 10 will be turned off manually or automatically by the photoelectric control circuit 46 as the last part 45- of the paint A color passes out of the spray region of the spray gun 10. Thereupon, the operator will close air valve 40, causing the paint A valve 32a to move to its seat. The several valves and switches will then stand in the position shown in the drawings.

With paint A shut off, air will pass from lines 29 and 43 through valve 40, through valve 41 and through valve 42 to line 58, as in the modification shown in FIG. 1. At the same time, air will pass through branch line 39 to valve 36 thus causing the solvent valve 320 to open and permit the flow of solvent or cleaner from container C into the manifold 33 and thence through regulator 18 into the fluid line 17 leading to the spray gun. As soon as air appears in line 58, however, the air operated switch 28 is closed, closing the circuit to winding 27 and causing electrically operated valve 26 to move to its open position and impose an air pressure on the voltage control valve cylinder 24 and thus move valve 25 to vent position, opening switch 23 to shut 011 the voltage on an electrostatic system and also to admit air pressure to line 60 which operates the automatic fluid override valve 56. When the valve 56 moves to its open position, air flows from the line 64, at the intermediate pressure determined by regulator 65, through the valve 57 and into the fluid pressure override line 66 to the regulator 19. The regulator 19 thence imposes control air through line 68 on the fluid pressure regulator 18 at a higher pressure, raising the pressure of fluid in line 17 leading to the spray gun.

The spray gun, meanwhile, remains closed since the photoelectric control circuit 46 has become inactive and has permitted valve 47 to move from its open to its closed or vented position. This has taken the air pressure off the air operated valve 48 so that no air appears in the pneumatic cylinder 11 which controls the opening of the gun 10.

The higher pressure fluid in line 17, since it cannot pass the closed fluid valve 14 in the spray gun 10, passes out past check valve 77 and into the waste container W. The flow of solvent continues until the manifold 33, the fluid chamber of the regulator 18 and the line 17 have all been flushed at high pressure.

As in the form shown in FIG. 1, the operator will receive a signal from indicator 70 at the end of a time period suflicient to completely purge the paint-containing portions of the system ahead of the spray gun 10. When indicator 70 is actuated, the operator can change paint by opening valve 41 controlling paint B, thus imposing an air pressure on line 38 into cylinder 35 and opening valve 32!). When valve 41 controlling paint B has moved from its full line to its dotted line position to permit air to flow through the valve 41 to the control cylinder 35 for valve 32!), the air circuit to line 58 is broken, and air pressure from this line is vented through valve 41 to atmosphere. However, because of the time delay imposed by the time delay element 72, the override pressure on regulator 19 will persist until the time delay device 72 times out. This causes paint B to fill the system including the manifold 33, regulator valve 18 and line 17 at high pressure. There may be some spillage of paint out of line 17 onto the waste container but this need not persist for any great length of time.

Assuming that no new part has yet come within the range of the spray gun and actuated the photoelectric control circuit 46, the operator can purge the last one or two ccs. of paint from the spray gun 10 by operating the manual control valve 54 and causing control air to flow through the branch line 52, the valve 54, the valve 48 and into the line 53 running to the gun air cylinder 11.

This moves the gun piston 12 back and opens the gun 10. A small puff of paint of the paint A color will be forced out of the system ahead of the new color. If valve 54 is then manually returned to its closed, upper position shown in full lines in the drawings, the gun 10 will not again operate until such time as a part 45 is within the operating range of the gun. Thereafter, the system will spray paint of the new color from container B through valve 32b into the manifold 33, through the regulator 18 and the line 17 at the normal spraying pressure, since the override pressure in line 66 will have returned to normal. The normal pressure appearing in line 17 is insufficient to open check valve 77 so that paint from line 17 will pass through the normal fiuid passage 14 in the gun 10 whenever the fluid passage is opened.

FIGURE 3 shows a system embodying two important features that are applicable to the embodiments of the invention disclosed in FIGS. 1 and 2. The system there shown makes provision for spraying coating materials of widely varying viscosity by the inclusion of individual pressure regulators 100, 101 and 102 in series with the main regulator control valve 19 which governs the pressure applied to the fluid regulator valve 18.

Each of the pressure regulator valves 100, 101 and 102 is connected in an identical air circuit so that a description of one will suflice for the others. In FIG. 3, it will be seen that whenever air is applied to the paint valve operating cylinder 35 through line 38, to open paint valve 32b, air also enters a branch connection 104 to the pressure regulator valve 101. The pressure of this air is the same as the pressure in the main supply line 29 (less small losses in the valves). Regulator 101 drops this pressure to a smaller pressure determined by its setting and applies the smaller pressure to a line 105 leading past an outwardly opening check valve 106 to an air manifold 107 and thence by line 108 to the control chamber of the main regulator valve 19. The setting OLf the main regulator valve 19 is thus changed and, as a consequence, the pressure on the fluid regulator valve 18 is adjusted. if, for example, fluid has been sprayed at relatively high pressure due to a high viscosity, valve 18 will have been adjusted by valve 19 to cause the passage of high pressure fluid to the spray gun 10. Upon the introduction of a lower viscosity paint by the opening of valve 32a, for example, it will be desirable to lower the fluid pressure. This is accomplished automatically by preselecting the setting of regulator valve 102 in series with the control cylinder for valve 32a to cause a lower pressure to be imposed on the main regulator valve 19, and thus a lower control pressure on the fluid pressure regulator valve 18. Upon a closure of valve 32a and a reopening of valve 3212 the pressure conditions to the main regulator will revert to those determined by the setting of regulator 101.

This modification of the invention shown in FIG. 3 also adds an air actuated dump valve 110 in the passage to the Waste container W, replacing check valve 77 shown in FIG. 2. The dump valve is opened during a color change operation by an air cylinder 111 that receives air whenever a color change operation starts and air is introduced into line 60 leading to the fluid pressure override valve 56. The connection between line 60 and cylinder 111 is designated 112. Thus, the dump valve 110 will be held open during that part of the color change cycle in which flushing material or solvent is introduced and also during filling of the new color paint by reason of the operation of the time delay device 72.

As in the (form shown in 'FIG. 2, the spray gun 10 is closed during the time the system is flushed, but in this instance the spray gun is deliberately opened during the last portion of the color change operation. To accomplish this, an air operated spray gun control valve 115 is provided, the position of which changes when the override system is operating only under the influence of the time delay device 72. In its dotted line position, the valve 115 will admit air under pressure from line 60 (whenever present) to the spray gun cylinder 12 to open the gun. In its second or vent position, shown in full lines, the spray gun cylinder 11 will be vented through line 53, valve 48, valve 54 and valve 115.

The valve 115 is actuated to the vent position whenever high pressure air apears in line 58 at the start of the color change operation when the operator has turned all of the paint valve control devices 40 and 41 off and opened the solvent control device 42. Thus the spray gun will immediately turn oflf. When the operator pulls one of the paint control devices to open position, the pressure in line 58 is dissipated so that valve 115 moves to its dotted line position and connects line 60, in which there is still pressurized air, to the gun control cylinder 11. The spray gun then opens and will remain open so long as line 60 contains air under pressure. This period is established by the time delay device 72. It will thus be seen that valve 115 operates to hold the spray gun closed during a first part of the color change operation and to open the gun during the second part of the operation.

Under these conditions at the second part of the color change operation, the spray gun and the dump valve 110 are both open and the lines 33, the body of the fluid regulator 18 and line 17 are being filled with paint of the selected new color. Since these lines have been filled with solvent, the solvent is displaced rapidly at override pressure, with part passing out of the spray gun 10 and part passing through the dump valve 110. That portion of the solvent passing through the spray gun displaces the paint of the initial color trapped in the gun body. This flow persists until the time delay device 72 times out, opening the circuit to solenoid 27 and shifting valve 26 to dissipate the pressure from line 60. Thereupon both the pump valve 110 and the spray gun cylinder 11 will be vented through valve 26 and the gun will close. The time established by the time delay device 72 is selected to assure filling the system with paint of the new color.

:Once the automatic air actuated valve 115 moves to vent position, control of the opening and closing of the spray gun by its cylinder 11 reverts to the air operated valve 48 previously described.

While the invention has been described in conjunction with a specific form and disposition of parts using a single spray gun, it is to be understood that the control appara tus may be used to control a plurality of individual guns connected in parallel and positioned to simultaneously spray all surfaces of large and complex objects. In such a multiple installation, each gun may be provided with its own separate regulator valve 18 and control regulator 19, with pneumatic and coating fluid supply lines from a common control apparatus. Various other modifications and changes may be made without departing from the scope of the invention as defined in the appended claims.

What I claim is:

1. In a control for a spray apparatus in which fluid material is fed to and discharged from a spray gun, said spray gun having a fluid supply passage, and having a pneumatic means to turn said spray gun on and ofl, first control means to actuate said pneumatic means to the on position, a fluid pressure regulator valve interposed in said supply passage, the discharge pressure of said regulator valve being responsive to a control air pressure, means to maintain a relatively low control air pressure on said regulator valve and thus a relatively low fluid pressure in said supply passage during normal spraying, override means to impose a relatively high control air pressure on said regulator valve and thus a relatively high fluid pressure in said supply passage during other operation of said spray gun, and common means to actuate said override means and said first control means to the on position, whereby material in said fluid supply passage may be rapidly replaced irrespective of said first control means.

2. In a control for a spray apparatus in which fluid material is fed to and discharged from a spray gun, said spray gun having a fluid supply passage, and having a pneumatic means to turn said spray gun on and off, first control means responsive to the presence of an article to be sprayed to actuate said pneumatic means to the on position and to actuate said pneumatic means to the off position in the absence of an article to be sprayed, a fluid pressure regulator valve interposed in said supply passage, the discharge pressure of said regulator valve being responsive to a control air pressure, means to maintain a relatively low control air pressure on said regulator valve and thus a relatively low fluid pressure in said supply passage during normal spraying, override means to impose a relatively high control air pressure on said regulator valve and thus a relatively high fluid pressure in said supply passage during other operation of said spray gun, and common means to actuate said override means and said first control means to the on position regardless of the presence or absence of an article to be sprayed, whereby material in said fluid supply passage may be rapidly replaced irrespective of said first control means.

3. In a control for a spray apparatus in which fluid is fed to and discharged from a spray gun, said spray gun having a fluid supply passage, a fluid pressure regulator valve interposed in said supply passage, the discharge pressure of said regulator valve being responsive to a control air pressure, means to maintain a relatively low control air pressure on said regulator valve and thus a relatively low fluid pressure in said passage during normal spraying, a fluid manifold having a discharge port connected to said supply passage, said manifold having an inlet port for each of a plurality of fluids, a separate valve means interposed between each fluid source and a respective inlet port of said fluid manifold and having open and closed positions, a separate operator for each of said valve means to move said separate valve means to open or closed positions, interlocking means to prevent actuation to the open position of more than one of said separate valve means at any one time, an override means to impose a relatively high control air pressure on said regu lator valve and thus a relatively high pressure in said fluid supply passage during other operation of said spray gun, and an interconnection between said separate valve operators and said override means so arranged that said override means is operable only when a predetermined one of said separate valve means is in open position.

4. The control for a spray apparatus as defined in claim 3 and a second override means operable irrespective of the positions of said separate valve means whereby a relatively high control air pressure can be imposed at any time on said regulator valve to cause a relatively high pressure in said fluid supply passage during other operation of said spray gun.

5. The control for a spray apparatus defined in claim 3, and means including a time delay means to maintain said relatively high pressure in said fluid supply passage for a predetermined time after said separate operators have been positioned to close said predetermined one of said separate valve means.

6. The control for a spray apparatus defined in claim 3 in which said override means is pneumatically actuated and in which said separate operators include pneumatic valves connected in series in a pneumatic circuit between said override means and a source of air pressure whereby operating air can pass to said override means only when said separate operators are positioned to open said predetermined one of said separate valve means.

7. In a spraying apparatus in which a plurality of fluids are selectively fed to and discharged from a comman spray gun, the combination of a fluid pressure regulator valve adjacent the spray gun and discharging fluid thereinto at a relatively low pressure during normally continuous spraying operation, a fluid manifold having a discharge port connected to said fluid pressure regulator valve and an inlet port for each of said plurality of fluids, a separate valve means interposed between each fluid source and a respective inlet port of said manifold and having open and closed positions, interlocking means to prevent actuation to the open position of more than one separate valve means at any one time, one of said separate valve means being operable to control the flow of a cleaning fluid to said manifold, said interlocking means being constructed and arranged to cause cleaning fluid to flow to said manifold when all of the remainder of said valve means are closed, and override means to increase the discharge pressure of said regulator valve and of said fluid at least whenever said cleaning fluid valve is open.

8. In a spraying apparatus as defined in claim 7 and means to indicate duration of the time of opening of said cleaning fluid valve.

9. In a control for a spray apparatus in which fluid material is fed to and discharged from a spray gun, pneumatic means to turn said spray gun on and off, said spray gun having a fluid supply passage, a fluid pressure regulator valve interposed in said supply passage, the discharge pressure of said regulator valve being responsive to a control air pressure, means to maintain a relatively low control air pressure on said regulator valve and thus a relatively low fluid pressure in said supply passage during normal spraying, override means to impose a relatively high control air pressure on said regulator valve and thus a relatively high fluid pressure in said supply passage during other operation of said spray gun, and a by-pass means connected to said supply passage and opened when said relatively high fluid pressure is imposed on said supply passage and when said pneumatic means has turned said spray gun off.

10. The control defined in claim 9 in which said bypass means includes a valve-controlled passage connected immediately adjacent said spray gun.

11. In a control for a spray apparatus in which fluid is fed to and discharged from a spray gun, said spray gun having a fluid supply passage, a fluid pressure regulator valve interposed in said supply passage, the discharge pressure of said regulator valve being responsive to a control air pressure, means to maintain a relatively low control air pressure on said regulator valve and thus a relatively low fluid pressure in said passage during normal spraying, a fluid manifold having a discharge port connected to said supply passage, said manifold having an inlet port for each of a plurality of fluids, a separate valve means interposed between each fluid source and a respective inlet port of said fluid manifold and having open and closed positions, a separate operator for each of said sep arate valve means to move said separate valve means to open or closed positions, interlocking means to prevent actuation to the open position of more than one of said separate valve means at anyone time, pneumatic means to open and close said spray gun, an override means to impose a relatively high control air pressure on said regulator valve and thus a relatively high pressure in said fluid supply passage, a series interconnection between said separate valve and said override means to introduce air under pressure in a control line for said override means when only a predetermined one of said separate valve means is in open position, and a dump valve in said fluid supply passage having an open and closed position, and a control for said dump valve operable to open said dump valve whenever air under pressure is introduced into said control line for said override means.

12. The control for a spray gun as defined in claim 11, and means including a time delay means to maintain said override means in operation and said relatively high pressure in said fluid supply passage for a predetermined time after said separate operators have been positioned to close said predetermined one of said separate valve means and the air under pressure in said control line has been dissipated.

13. The control for a spray gun as defined in claim 12, and a control for said pneumatic gun opening means including a valve operating to close said spray gun when air under pressure is introduced into said control line for said override means.

14. The control for a spray gun as defined in claim 12, and a control for said pneumatic gun opening means including a valve operating to close said spray gun when air under pressure is introduced into said control line for said override means and to open said spray gun when the air under pressure is said control line has been dissipated.

15. In a control for a spray apparatus in which fluid is fed to and discharged from a spray gun, said spray gun having a fluid supply passage, a fluid pressure regulator valve interposed in said supply passage, the discharge pressure of said regulator valve being responsive to control air pressures to maintain relatively low fluid pressures in said passage during normal spraying a plurality of airregulator valves associated with a plurality of separate fluid valves whereby actuation of each of said separate fluid valves causes its respective air-regulator valve to control said fluid regulator valve to etfect a different spray pressure for said spray gun, a fluid manifold having a discharge port connected to said supply passage, said manifold having an inlet port for each of a plurality of fluids, said separate valve means being interposed between each fluid source and a respective inlet port of said fluid manifold and having open and closed positions, a separate operator for each of said separate valve means to move said separate valve means to open or closed positions, interlocking means to prevent actuation to the open position of more than one of said separate valve means at any one time, an override means to impose a relatively high control air pressure on said fluid regulator valve and thus a relatively high pressure in said fluid supply passage during other operation of said spray gun, and an interconnection between said separate valve operators and said override means so arranged that said override means is operable only when a predetermined one of said separate valve means is in open position.

References Cited UNITED STATES PATENTS 3,121,024 2/1964 Wampler et al. 118-2 3,145,930 8/1964 Herklotz 23915 WALTER A. SCHEEL, Primary Examiner.

J. P. MCINTOSH, Assistant Examiner.

US. Cl. X.R. 1l89, 302; 239-70 g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION v Patent No. },50 ,O92 Dated June 17, 1969 Inventor (s) Erhard KOCk It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 12, line 39, after "said" insert separate SIGNED ANU SEALED OCT 2 l 1969 wmxm E. suaunm, m. Amflfi g Offioer Gomissioner or Yatanta

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Classifications
U.S. Classification118/703, 118/302, 159/4.1, 118/707, 239/112, 239/70
International ClassificationB05B12/00, B05B5/00, B05B12/14, B05B5/16
Cooperative ClassificationB05B12/14, B05B5/16
European ClassificationB05B5/16, B05B12/14