US3913844A

US3913844A - Safety spray gun trigger

Info

Publication number: US3913844A
Application number: US450927A
Authority: US
Inventors: John E Petrovic
Original assignee: Graco Inc
Current assignee: Graco Inc
Priority date: 1974-03-13
Filing date: 1974-03-13
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21
Also published as: USB450927I5

Abstract

Apparatus disclosed for disabling a paint spray gun triggering mechanism when the spray tip is removed, as for cleaning or replacement. The apparatus disables the spray gun trigger by shifting the trigger pivot point to an inactive position.

Description

United States Patent Petrovic Oct. 21, 1975 SAFETY SPRAY GUN TRIGGER [56] References Cited [75] Inventor: John E. Petrovic, Coon Rapids, UNITED STATES PATENTS 3,410,491 11/1968 Malec 239/526 [73] Assignee: Graco Inc., Minneapolis, Minn 3,780,953 12/1973 Malec 239/526 [22] Filed: 1974 Primary ExaminerM. Henson Wood, Jr. 2 APPL 450 927 Assistant Examiner.lohn J. Love- Attorney, Agent, or Firm-Paul L. Sjoquist [44] Published under the Trial Voluntary Protest Program on January 28, 1975 as document no. B 450,921 [57] ABSTRACT Apparatus disclosed for disabling a paint spray gun [52] US. Cl. 239/526; 239/600; 251/89; triggering mechanism when the spray tip is removed, 251/1 1 1 as for cleaning or replacement. The apparatus disables [51] Int. Cl. B05B 11/00 the spray gun trigger by shifting the trigger pivot point [58] Field of Search 239/526-528, to an inactive position.

12 Claims, 2 Drawing Figures US. Patent Oct. 21, 1975 3,913,844

SAFETY SPRAY GUN TRIGGER This invention relates to a spray gun apparatus, and more particularly to a safety trigger for insuring that high pressure fluid cannot be sprayed when the proper spray gun tip is not attached.

The two basic techniques of paint spraying are air spraying and airless spraying, both of which are accomplished using spray guns usually having very small spray orifices through which the paint mixture is ejected. According to the air spray technique, the paint is intermixed with pressurized air within the spray gun and the composite mixture is sprayed through an orifice under pressure. In this case, the air pressure required is typically on the order of 10-50 pounds per square inch. In airless spraying, the paint itself is maintained under high hydraulic pressures, typically SOD-3,000 pounds per square inch, and this highly pressurized paint is forced through the spray orifice to create the necessary atomization. Because of the relatively small size of the orifice opening in both cases, it is frequently necessary to remove the orifice for cleaning and/or unplugging. When the orifice in an airless spray gun is removed there exists a potential hazard to the operator because of the presence of paint in the spray gun under high hydraulic pressure. If the trigger on the spray gun should accidentally be actuated, this high pressure paint could be ejected from the gun in a high velocity stream which, under certain circumstances, may have sufficient force to penetrate the body of a person. It has therefore been necessary to provide safety trigger features on airless spray guns to lock the trigger against activation whenever the spray gun is not actually being used for spraying. A trigger-locking feature is described in U.S. Pat. No. 3,633,828, issued Jan. 11, 1972 to the common assignee of this invention, which trigger safety feature can be activated by the operator to prevent accidental triggering of the spray gun.

The present invention provides yet another improvement in trigger safety devices, and provides an improvement which may be used in conjunction with the feature described in the above-named patent. This invention disengages the trigger actuating mechanism whenever the spray tip, including the spray orifice, is removed from the gun. Because the trigger disabling mechanism comes into play whenever the spray tip is removed, it requires no other operator manipulation. As such, it provides a completely safe trigger disabling mechanism which does not depend upon operator actions such as are required with other trigger safety devices.

Briefly, the invention comprises a slidable rod positioned within the body of the spray gun, and having its first end abutting the threaded nut which holds the spray tip on the spray gun. The second end of the slidable rod abuts against the gun trigger pivot pin and serves to hold the pivot pin in an operable position when the spray tip nut is tightened. When the spray tip nut is loosened, such as for the purpose of removing the spray tip from the gun, the rod slides forward and relieves the force on the trigger pivot pin, allowing the pin to move freely within a constrained area. When the pin is freely movable it can provide no pivot point from where a force can be leveraged to cause the trigger to activate the spray gun valving mechanism. The trigger effectively hangs loosely in its mounting and becomes totally disengaged from triggering operation.

Accordingly, it is an object of this invention to provide a trigger safety apparatus for disabling a paint spray gun whenever the spray tip is removed.

It is a further object of this invention to disconnect the trigger mechanism from operable linkage with the paint spray valve in an airless spray gun whenever the airless spray tip is removed for cleaning or maintenance.

It is another object of this invention to provide a trigger safety shut-off mechanism which will automatically become activated upon disconnecting the gun spray tip, and without further operator activity.

These and other objects and advantages of this invention will become apparent with reference to the following description and claims, and from the drawings, in which:

FIG. 1 illustrates a spray gun having the inventive improvement incorporated therein; and

FIG. 2 illustrates the spray gun in a disabled configuration.

Referring to the drawings, FIG. 1 illustrates a spray gun having the inventive improvement incorporated therein. Portions of the spray gun are shown in crosssection to facilitate the understanding of the working components associated with this invention. Trigger 10 actuates the spraying mechanism of the spray gun by pulling it backward toward handle 12. Trigger l pivots about a pin 15 which protrudes through the body of the spray gun and through holes near the upper end of trigger which are sized to accept pin 15. Pin has appropriate flanges or other locking means at each of its ends to prevent it from falling out of the gun. The pin 15 passage 18 through the gun body is constructed as an elongated slot for purposes hereinafter to be described in conjunction with the operation of the invention.

The spray gun is actuated by means of withdrawing valve rod 17 from its seat near the front of the spray gun. Valve rod 17 is withdrawn when trigger 10 is squeezed, there being a suitable connection between trigger 10 and the valve rod 17 retracting mechanism. For purposes of explanation, this is illustrated as contact point 19, it being assumed that a suitable trigger edge bears against a shoulder on the valve rod retracting mechanism at contact point 19. The precise trigger retracting mechanism is not critical to this invention, it being required only that a trigger-valve rod mechanism contact point be established for actuating the valve rod mechanism. When valve rod 17 is retracted, paint or other spray medium is admitted into the front passages of the spray gun and is sprayed through spray tip 20. The paint spray is typically finely atomized and, in the case of an airless spray gun, is forced through the small spray tip 20 orifice under a high hydraulic pressure. This high hydraulic pressure exists at all points rearward of spray tip 20 within the spray gun, and in particular exists within spray passage A spray tip retainer nut is threaded on to the spray gun and tightly clamps spray tip 20 against the gun. Retainer nut 25 also bears against the end of slidable rod 23 and holds rod 23 in the position shown. The other end of rod 23 bears against pin 15 to force pin 15 against the rearward edge of slotted passage 18. Thus, the pivot point of trigger 10, as determined by the position of pin 15 is located at the rearward portion of slotted passage 18.

It frequently becomes necessary to remove spray tip 20 for cleaning. This can readily be accomplished by unscrewing retainer nut 25 from the end of the spray gun. However, when the spray tip 20 is removed, as illustrated in FIG. 2, the paint passage 21 becomes directly exposed. Thus, under these conditions, if trigger 10 is inadvertently squeezed high pressure paint will be ejected through paint passage 21 out of the spray gun without benefit of the atomizing characteristics of the spray tip. The result is that a high pressure stream of 10 paint is ejected, which stream may be injurious to and may penetrate objects against which it is directed. Since this high pressure stream has sufficient force and has been known to penetrate the skin ofa person, it becomes necessary to provide safety features to avoid this probability. One safety feature known in the prior art is trigger safety 27, which is a safety latch for preventing trigger movement. When trigger safety 27 is rotated 90 from the position shown it bears against the rear surface of trigger l and prevents it from being squeezed toward handle 12. However, the effectiveness of trigger safety 27 depends upon the operator remembering to rotate it 90.

FIG. 2 illustrates the additional safety feature of the present invention. When tip retainer nut 25 is removed to enable replacement or cleaning of spray tip 20 it is no longer available to hold slidable rod 23 against pin 15. Therefore, if trigger is squeezed under these conditions, pin will slide forwardly in slotted passage 18 until it reaches the forward edge of slotted passage 18. In this position the pivot arm created between pin 15 and contact point 19 is insufficient to actuate the valve mechanism. Movement of pin 15 in slot 18 to the most forward position also allows trigger 10 to contact safety 27, thus preventing further movement of the trigger 10. Therefore, the valve 17 cannot be retracted to allow the escape of high pressure paint through paint passage 21. Trigger 10 is effectively disabled and the spray gun becomes inoperative until tip retainer nut is again replaced on the spray gun. The invention thereby provides a completely safe disabling mechanism for the spray gun.

Variations in the embodiment shown in the drawings may be made within the spirit of this invention. For example, rod 23 may be spring-loaded within the spray gun housing to force it away from contact with pin 15 under all circumstances except when tip retainer nut 25 is securely attached. Likewise, the end of rod 23 may be recessed within the spray gun housing to prevent the accumulation of paint thereon. Of course, rod 23 may be provided with a suitable shoulder at any convenient point to hold it within the spray gun housing and to insure that it does not fall out when the spray gun is moved without the tip retainer nut 25 being properly positioned. All of these variations and others are contemplated within the spirit of this invention, the inventive embodiment being directed essentially to an apparatus for controlling the spray gun trigger pivot in a manner to allow disabling of the trigger actuating mechanism when the spray tip is removed.

I claim:

1. A spray gun trigger disabling apparatus effective on removal of the spray gun spray tip retainer, comprismg means for pivoting said trigger about a pivot point for providing a spray gun trigger actuating leverage force;

means for moving said pivot point to a position of disabling said spray gun trigger actuating leverage force;

a slidable rod connected between said means for moving the pivot point and the spray tip retainer, whereby the removal of the spray tip retainer causes the pivot point to move to the disabling position.

2. Apparatus as claimed in claim 1 wherein the means for pivoting said trigger further comprises a pin extending between said trigger and said spray gun.

3. Apparatus as claimed in claim 2 wherein said means for moving said pivot point further comprises a slotted passage in said spray gun and within which said pin resides.

4. Apparatus as claimed in claim 3 wherein said slidable rod extends between said slotted passage and the edge of said spray tip retainer.

5. Apparatus as claimed in claim 4, wherein the length of said slidable rod is selected to hold said pin in an actuating position when said tip retainer is secured on said spray gun.

6. A spray gun safety apparatus for disabling the spray gun trigger on removal of the spray tip retainer from the spray gun housing, comprising:

a threaded portion on the spray gun for accepting and securing said spray tip and spray tip retainer;

a pivot pin contacting said trigger with the spray gun housing;

a slotted passage in said spray gun housing for accepting said pivot pin; and

a slidable rod extending between said slotted passage and said spray tip retainer to hold said pivot pin in an actuating position when said tip retainer is se cured.

7. Apparatus as claimed in claim 6, further comprising a passage in said gun housing of diameter slightly greater than said slidable rod, said passage extending between said slotted passage and a spray gun surface adjacent the edge of said secured tip retainer, wherein said slidable rod resides.

8. Apparatus as claimed in claim 7 wherein said pivot pin contacts the trigger near the end of said trigger.

9. A spray gun trigger disabling apparatus effective on removal of the spray tip and retainer to prevent actuation of the spray gun fluid valve, comprising:

a pivot pin passing through the spray gun body and through the trigger;

an oversized passage in said spray gun body for passage therethrough of said pivot pin, whereby said pivot pin has freedom of movement therein to at least two positions;

a movable member extending between said retainer and said pivot pin, whereby said member holds said pivot pin in a first position when said retainer retains said spray tip and releases said pivot pin to a second position when said retainer is removed.

10. The apparatus of claim 9, further comprising a rotatable safety latch means in said spray gun and extending into the path of movement of said trigger, said latch means having a first position restraining trigger movement when said pivot pin is in its first position and having a second position restraining trigger movement when said pivot pin is in a second position.

11. The apparatus of claim 10, wherein said movable member further comprises a rod slidable within a passage in said spray gun.

12. Apparatus as claimed in claim 11, wherein said oversized passage in said spray gun body further comprises a slot elongated in the direction of said retainer.

Claims

1. A spray gun trigger disabling apparatus effective on removal of the spray gun spray tip retainer, comprising means for pivoting said trigger about a pivot point for providing a spray gun trigger actuating leverage force; means for moving said pivot point to a position of disabling said spray gun trigger actuating leverage force; a slidable rod connected between said means for moving the pivot point and the spray tip retainer, whereby the removal of the spray tip retainer causes the pivot point to move to the disabling position.

3. Apparatus as claimed in claim 2 wherein said means for moving said pivot point further comprises a slotted passage in said spray gun and within said pin resides.

6. A spray gun safety apparatus for diabling the spray gun trigger on removal of the spray tip retainer from the spray gun housing. comprising: a threaded portion on the spray gun for accepting and securing said spray tip and spray tip retainer; a pivot pin contacting said trigger with the spray gun housing; a slotted passage in said spray gun housing for accepting said pivot pin; and a slidable rod extending between said slotted passage and said spray tip retainer to hold said pivot pin in an actuating position when said tip retainer is secured.

9. A spray gun trigger disabling apparatus effective on removal of the spray tip and retainer to prevent actuation of the spray gun fluid valve, comprising: a pivot pin passing through the spray gun body and through the trigger; an oversized passage in said spray gun body for passage therethrough of said pivot pin, whereby said pivot pin has freedom of movement therein to at least two positions; a movable member extending between said retainer and said pivot pin, whereby said member holds said pivot pin in a first position when said retainer retains said spray tip and releases said pivot pin to a second position when said retainer is removed.