U.S. patent number 3,913,844 [Application Number 05/450,927] was granted by the patent office on 1975-10-21 for safety spray gun trigger.
This patent grant is currently assigned to Graco Inc.. Invention is credited to John E. Petrovic.
United States Patent |
3,913,844 |
Petrovic |
October 21, 1975 |
SAFETY SPRAY GUN TRIGGER
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.
Inventors: |
Petrovic; John E. (Coon Rapids,
MN) |
Assignee: |
Graco Inc. (Minneapolis,
MN)
|
Family
ID: |
23790091 |
Appl.
No.: |
05/450,927 |
Filed: |
March 13, 1974 |
Current U.S.
Class: |
239/526; 251/89;
239/600; 251/111 |
Current CPC
Class: |
B05B
9/01 (20130101); B05B 15/00 (20130101); B05B
12/0022 (20180801) |
Current International
Class: |
B05B
15/00 (20060101); B05B 9/01 (20060101); B05B
9/00 (20060101); B05B 011/00 () |
Field of
Search: |
;239/526-528,583,600
;251/89,90,98,111,113 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wood, Jr.; M. Henson
Assistant Examiner: Love; John J.
Attorney, Agent or Firm: Sjoquist; Paul L.
Claims
I claim:
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.
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 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 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.
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.
Description
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 500-3,000
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 cross-section 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 10 pivots
about a pin 15 which protrudes through the body of the spray gun
and through holes near the upper end of trigger 10 which are sized
to accept pin 15. Pin 15 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 21.
A spray tip retainer nut 25 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 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 of a 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.degree. from the position shown it bears
against the rear surface of trigger 10 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.degree..
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 10 is
squeezed under these conditions, pin 15 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 25 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.
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