Note: Descriptions are shown in the official language in which they were submitted.
zo34z'~~
.'.:. TSM0116PUS -1-
BPRAY GDN 811VING A ROTATABLB BPRAY HElID
This invention relates to spray guns and, in
particular to spray guns including spray heads with at
least one shaping air orifice to provide fanning air.
In conventional paint spray guns, a stream of
paint under pressure is discharged from a relatively
small orifice in a nozzle while air under pressure is
discharged into the stream from an annular opening
surrounding the nozzle to atomize the stream of paint ,
into a spray of fine particles. As it moves away from
the gun, the spray defines a conical pattern whose apex
is at the nozzle.
It is often desired to modify the circular
cross-section of the normal conical spray pattern. This
process is called fanning. This is typically
accomplished by providing at the front end of the gun
a spray head including an air cap having a pair of
diametrically opposed ports which direct air j ets toward
opposite sides of the spray pattern to flatten the sides
of the conical pattern.
In many prior art paint spray guns, adjustment
of the fanning of the air is made by rotatably adjusting
the air cap. This adjustment exerts a valuing action
which establishes a maximum airflow when the
diametrically opposed valve ports lie in either a
vertical plane containing the nozzle access or a
horizontal plane containing the nozzle access.
2034273
TSM0116PUS -2-
Numerous prior art patents disclose paint spray
guns in which fanning is adjustably controlled
independently of the rotative orientation of the air cap
by a valve member which is received within a spray gun
housing for movement between fully open and fully closed
positions. A manual operable mechanism adjusts the
position of the valve member in the housing. The
atomizing and fanning air are discharged from a single
chamber formed in the air cap forward of the valve
member prior to discharge into atomizing and fanning
ports. Examples of such prior art patents include U.S.
Patent Nos. 1,849,300, 2,740,670 and 4,744,518.
U.S. Patent Nos. 4,531,675 to Muck discloses
a paint spray gun including a nozzle assembly which can
be adjusted by a rotation plate to change air flow
patterns and thereby the paint pattern.
U.S. Patent No. 4,798,335 to Tachi et al
discloses a paint spray device with a rotating head and
air outlet ports for jetting out a stream of air in
order to vary the paint pattern.
U.S. Patent Nos. 4,214,708, 4,337,895 and
4,405,086 all show rotating atomizers.
one problem with such prior art paint spray
guns is that the air discharged from the fanning ports
3 o fail to uniformly flatten the sides of the conical spray
pattern against which they are directed and,
consequently, do not properly control the shape of the
20 3~ 273
spray pattern. This is caused by turbulence of the fanning
air. One result is that when multiple coats of spray paint
are to be applied to an article, the coats are not evenly
applied and excess paint is used. This is especially
troublesome in paint spray systems where the atomizing air has
a flow rate in excess of 5 CFH (cubic feet per minute) at the
spray head and a delivery pressure of less than 15 psi over
atmospheric pressure at the spray head.
Another problem with such guns is that the atomizing
air may not properly atomize the paint spray.
Still another problem is that with such guns the
spray pattern does not effectively reach the sides of a
article having multiple parallel sides such as a grill without
multiple reciprocating spray gun passes.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a
spray gun including a rotatable spray head for rotating
fanning air wherein the fanning air is derived from
pressurized air having a flow rate in excess of 5 CFM at the
spray head of the gun and a delivery pressure of less than 15
psi over atmospheric pressure at the spray head.
Still another object of the present invention is to
provide a spray gun including a rotatable spray head for
rotating the fanning air to more effectively control the
shaping and delivery of a conical spray pattern wherein at
least one spiral flow of fanning air
- 3 -
71087-269
p.
203273
is created by the rotating spray head and wherein the spray
head is rotatable in opposite directions depending on the
direction of movement of the spray gun.
According to a first broad aspect, the invention
provides in a spray gun including a housing assembly; an
annular spray head mounted at the forward end of said housing
assembly; said spray head having a central air discharge
orifice extending coaxially therethrough and at least one
shaping air orifice; a nozzle mounted on said housing assembly
coaxially of said cental air discharge orifice; said nozzle
having a liquid discharge orifice at its forward end for
discharging liquid under pressure in a forwardly directed
stream coaxially of said central air discharge orifice; first
passage means in said housing assembly for supplying liquid
under pressure to said liquid discharge orifice; chamber means
in the housing assembly; means for communicating pressurized
air having a flow rate in excess of 5 CFM (cubic feet per
minute) and a delivery pressure of less than 15 psi over
atmospheric pressure to the
chamber means; second passage means in said housing assembly
for communicating air from the chamber means to said central
air discharge orifice to atomize liquid discharge from said
liquid discharge orifice into a spray; third passage means in
said spray head for communicating air from the chamber means
to said at least one shaping air orifice in said spray head to
control fanning of the spray; the improvement comprising:
means for rotatably mounting the spray head on the housing
assembly; drive means for rotatably driving the spray head
- 4 -
71087-269
2034273
relative to the housing assembly to create at least one spiral
flow of shaping air; wherein said drive means includes a
reversible motor to drive the spray head and automatic control
means for automatically controlling the reversible motor and
for automatically controlling movement of the spray gun
wherein the at least one spiral flow of shaping air is capable
of automatically flowing in apposite directions dependent on
the direction of movement of the spray gun.
According to a second broad aspect, the invention
provides in a spray gun including a housing assembly; an
annular spray head mounted at the forward end of said housing
assembly; said spray head having a central air discharge
orifice extending coaxially therethrough and a pair of
diametrically opposed shaping air orifices, a nozzle mounted
on said housing assembly coaxially of said central air
discharge orifice; said nozzle having a liquid discharge
orifice at its forward end for discharging liquid under
pressure in a forwardly directed stream coaxially of said
central air discharge orifice; first passage means in said
housing assembly for supplying liquid under pressure to said
liquid discharge orifice; chamber means in the housing
assembly; means for communicating pressurized air having a
flow rate in excess of 5 CFM (cubic feet per minute) and a
delivery pressure of less than 15 psi over atmospheric
pressure to the chamber means; second passage means in said
housing assembly for communicating air from the chamber means
to said central air discharge orifice to atomize liquid
discharged from said liquid discharge orifice into a spray;
- 5 -
71087-269
203~2~3
third passage means in said spray head for communicating air
from the chamber means to said shaping air orifices in said
spray head to control fanning of the spray; the improvement
comprisings means for rotatably mounting the spray head on the
housing assembly; drive means for rotatably driving the spray
head relative to the housing assembly to create two spiral
flows of shaping air; wherein said drive means includes a
reversible air motor mounted on the housing assembly and
adapted to receive air under pressure to drive the spray head;
and control means for automatically controlling the reversible
air motor and for automatically controlling movement of the
spray gun; whereby the two spiral flows of shaping air are
capable of automatically flowing in opposite directions
dependent on the direction of movement of the spray gun.
The advantages accruing to a spray gun constructed
in accordance with the above are numerous. For example,
because the fanning air is created in a spiral flow, more
effective control of the spray pattern is provided since
turbulence is greatly reduced in the fanning air. Also, the
ZO liquid is more fully atomized. Hultiple coats of the liquid
spray are more evenly applied with less liquid spray wastage
and without dripping. Finally, because the sprayhead of the
spray gun can rotate in opposite directions, the spray gun can
more effectively apply the liquid spray to articles having
multiple sides such as grills.
Other advantages of the present invention will be
readily understood as the same becomes better understood by
- 5a -
,.., .
71087-269
203,273
reference to the following detailed description when
considered in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a view, partially broken away and in
cross-section, of a spray gun of the present
- Sb -
71087-269
20342'3
TSM0116PUS -6-
invention connected to a compressed air source:
FIGURE 2 is an enlarged view of the spray gun,
partially broken away and in cross-section, taken along
lines 2-2 of FIGURE 1; and
FIGURE 3 is a view, partially broken away and
in cross-section, of the spray gun taken along lines 3-
3 of FIGURE 2.
BEST MODB FOR CARRYING OtJT THE INVENTION
Referring to FIGURES 1, 2 and 3, there is
illustrated a spray gun constructed in accordance with
the present invention, and generally indicated at 10.
The gun 10 includes a housing assembly, generally
indicated at 12, which has an air inlet tube 14 and a
fluid inlet tube (not shown) which define input air and
input liquid coating passages 18 and 20, respectively.
The housing assembly 12 also has a compressed air inlet
tubes 22 and 23 which define air passages 24 and 25,
respectively, for the supply of compressed air.
The compressed air is provided by a compressed
air source 26 and is fluidly communicated to the air
inlet tubes 22 and 23 by a hose 28 under control of an
air solenoid 27. In turn, the solenoid 27 is controlled
by a controller 29 which may comprise any type of
automatic controller which may also control the movement
of the spray gun 10 in an automatic system.
The air source 26 may be a conventional factory
compressed air source. The compressed air operates a
reversible air motor supported on the spray gun 10 as
~,,, 2034273
TSM0116PUS
is described in detail below.
The gun 10 also includes an annular spray head,
generally indicated at 32, mounted at the forward end
of the housing assembly 12. In turn, the spray head 32
includes an air cap assembly, generally indicated at 34.
The air cap assembly 34 includes a housing 36 and an
internally threaded air cap fitting or nut 38 for
securing the air cap assembly 34 to a cylindrical
portion 40 of the spray head 32.
Referring specifically to FIGURE 3, the gun 10
further includes a nozzle or tip, generally indicated
at 42, having radially projecting wings 44. The nozzle
42 has an internal, tapered bore or liquid discharge
orifice 46 at its forward end 48 and is threadedly
secured within an internally threaded spool or barrel
50 at its rearward end 52. The nozzle 32 is preferably
sealed by a tip gasket (not shown).
The input air passage 18 is in fluid
communication with an annular air chamber 54 located
about the barrel 50 within an internal cylindrical
portion 51 of the housing assembly 12. In turn, the air
chamber 54 is in fluid communication with a circular air
discharge orifice 56 and first and second pairs of
diametrically opposed shaping air orifices 58 and 53
formed in the housing 36 of the air cap assembly 34.
The assembly 34 is threadedly connected to the rest of
the gun 10 by the fitting 38 so that the liquid
3o discharge orifice 46 formed in the nozzle 42 is
centrally disposed within the air discharge orifice 56.
2a~~~'~3
TSM0116PUS -g-
The gun 10 includes a turbine means or
mechanism, generally indicated at 55, having a forward
end 57 and a rearward end 59. The turbine mechanism 55
is located in the chamber 54 coaxially of the air
discharge orifice 56 for receiving pressurized air from
the chamber 54 at its rearward end 59 and creating a
spiral flow of air at its forward end 57. A turbine
mechanism having a similar structure and function is
illustrated in U.S.P.N. 4,911,365 having the same
Assignee as the present application.
The pair of diametrically opposed shaping air
orifices 58 and 53 are directed towards the coating
material sprayed from the nozzle 42 to partially atomize
the coating material and to shape the resulting pattern
of atomized liquid coating material.
The liquid coating passage 46 is in fluid
communication with a first passage or bore 60 formed in
the barrel 50. In turn, the first passage ~60
communicates with the liquid discharge orifice 46.
The gun 10 preferably includes a mounting rod
(not shown) for mounting the gun l0~to a spray fixture
for automatic operation under control of air control
signals at a control air passage 62. However, it is to
be understood that the gun 10 may be modified for manual
operation.
The flow of liquid coating material through the
barrel 50 and the nozzle 42 is controlled by a control
~~~~~'~3
TSM0116PUS _g_
pin or valve, generally indicated at 64. The pin 64 has
a tapered forward end portion 66 which selectively opens
or closes the liquid discharge orifice 46 in the nozzle
42 upon axial movement thereof.
The air control signals in the passage 62
control the position of a piston member 68
concentrically mounted rearward on a rear end portion
70 of the pin 64 within the passage 62. The piston 68
is fixedly secured to the rear end portion 70 of the pin
64 so that the pin 64 moves axially when the piston
member 68 moves within the passage 62. In other words,
the pin 64 moves axially between its open and closed
positions when the piston member 68 receives control
signals on one end surface thereof.
A packing nut and bolt assembly 72 fluidly
seals the pin 64 within the barrel 50. A locking nut
74 secures the barrel 50 within the housing assembly 12:
Preferably, an adjustment screw (not shown) adjusts the
position of the pin 64 within the barrel 50 and a check
nut (not shown) secures the desired position.
The spray head 32 is rotatably mounted on the
housing assembly 12 and, in particular, on the
cylindrical portion 51 by bearings 76. The bearings 76
are held spaced apart on the portion 51 by snap rings
78.
The cylindrical portion 40 is preferably
integrally formed with a driven gear 80 of a gear
mechanism, generally indicated at 82. The driven gear
TSM0116PUS -10-
80 is coupled to a drive or pinion gear 84 which is
mounted on a rotary drive shaft 86 of a reversible air
motor, generally indicated at 88. The drive shaft 86
is mounted for rotation within the housing assembly 12
by supports 90 and 92 at opposite ends thereof.
Various apertured, annular plates or blades 94
are mounted on the shaft 86 to rotate the shaft 86 when
compressed air flows through the air inlet tube 22 and
across the blades 94. After flowing across the blades
94 the compressed air exits the air motor 88 at vents
at the rear of the motor.
Alternatively, the gear mechanism 82 may be
driven by a cable which is coupled to the drive gear 92
at one end thereof and at its opposite end to an air
motor. obviously, many other arrangements can be
provided for rotatably driving the spray head 32. For
example, gear mechanism 82 may be eliminated by
attaching air fins to the cylindrical portion 40 in the
space defined by the cylindrical portions 40 and 51.
Pressurized air passing over the fins would cause the
cylindrical portion 40 and, consequently, spray head 32
to rotate.
The spiral flows of air caused by rotating the
spray head and, consequently, the air cap assembly 34,
control fanning of the spray by minimizing turbulence
within the spray. Also, such fanning air assists in the
liquid atomization process. Such turbulence is
particularly troublesome when the air flow rate at the
air cap assembly 34 is in excess of 5 CFM and has a
~'~~~2'~3
TSM0116PUS -11-
delivery pressure of less than 15 psi. over atmospheric
pressure, as provided in U.S.P.N. 4,761,299 having the
same Assignee as the present application.
As can be readily appreciated by one of
ordinary skill in the art, the invention of FIGURES 1
through 3 can be conveniently employed with a manually
operable gun body, which may be either metallic or
plastic in construction.
The spray gun 10 of the present invention
provides numerous advantages. For example, rotation'of
the spray head 32 at a relatively constant speed of,
for example, 60 rpm, creates spiral flows of fanning air
at the shaping air orifices 58 to provide an effective
mechanism to control fanning of the liquid atomized
spray discharged from the nozzle 42. This is
particularly advantageous when applying multiple coats
of the liquid spray to more uniformly apply the coats
without using an excess of liquid. Also, the spray gun
10 provides air which effectively atomizes the liquid
spray. Finally, because the motor 88 is reversible, the
direction of rotation of the spray head 32 can be varied
depending on the direction of movement of the gun 10 to
more effectively spray the sides of multi-sided
articles, such as grills.
While the best mode for carrying out the
invention has been described in detail, those familiar
with the art to which this invention relates will
recognize various alternative ways of practicing the
invention as defined by the following claims.
