U.S. patent number 3,680,789 [Application Number 05/134,634] was granted by the patent office on 1972-08-01 for spray gun.
Invention is credited to Josef Wagner.
United States Patent |
3,680,789 |
Wagner |
August 1, 1972 |
SPRAY GUN
Abstract
A spray gun, particularly useful for spraying paints, having an
electric vibrator during a piston pump submerged in an oil bath
which hydraulically drives a diaphragm pumping the medium to be
sprayed to a spray nozzle and separating the medium from the piston
pump. The quantity of the medium to be sprayed is adjusted by
controlling the stroke of the piston.
Inventors: |
Wagner; Josef
(Friedrichshafen-Fischbach, DT) |
Family
ID: |
5768502 |
Appl.
No.: |
05/134,634 |
Filed: |
April 16, 1971 |
Foreign Application Priority Data
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Apr 18, 1970 [DT] |
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P 20 18 789.7 |
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Current U.S.
Class: |
239/332; 222/333;
239/350; 239/351 |
Current CPC
Class: |
B05B
9/0861 (20130101) |
Current International
Class: |
B05B
9/08 (20060101); B05b 009/04 () |
Field of
Search: |
;239/332,351,412
;222/333 ;184/24 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: King; Lloyd L.
Claims
I claim as my invention:
1. A spray gun which comprises a housing defining an oil sump, a
hydraulic piston pump in said housing adapted to be immersed in and
receive oil from said sump, an electric motor in said housing
driving said pump, a diaphragm pump driven hydraulically from said
piston pump, said diaphragm pump having an oil receiving chamber
communicating with the piston pump and a pumping chamber
communicating with the fluid medium to be sprayed, and said
diaphragm separating said two areas to isolate the piston pump and
oil sump from the pumping chamber media, and means for adjusting
the stroke of the piston to control the quantity of the medium
being sprayed.
2. A spray gun which comprises a head defining an oil sump, an
electric oscillating motor in said head, a piston pump in said sump
driven by said motor and adapted to be submerged in oil in the
sump, a lid on said head, an adjusting screw carried by said lid
controlling the stroke of said motor, a handle suspended from said
head, a control switch carried by said handle for energizing said
motor, a diaphragm pump suspended from said head having an inlet
adapted to communicate with the medium to be sprayed, a spray
nozzle receiving spray medium from said diaphragm pump, said
diaphragm pump having an oil chamber communicating with oil from
the piston pump and a pumping chamber communicating with the spray
medium and with the outlet nozzle, an inlet valve controlling
inflow to the pumping chamber, an outlet valve controlling outflow
from the pumping chamber, said diaphragm isolating the oil from the
spray medium, and ports in the piston pump replenishing oil from
the sump to the oil chamber of the diaphragm pump.
3. A portable electric spray gun especially adapted for spraying
paints, which comprises a hollow head defining an oil sump, an
electric motor mounted in said head, a piston pump receiving oil
from said oil sump driven by said electric motor, a handle
depending from said head, a control switch carried by said handle
controlling current flow to said electric motor in said head, a
diaphragm pump suspended from said head having an oil chamber
receiving oil from said piston pump and a pumping chamber, a
container for spray media suspended from said head communicating
with said pumping chamber of said diaphragm pump, an inlet valve
controlling flow from said container to said pumping chamber, a
spray nozzle communicating with said pumping chamber, an outlet
valve controlling flow from the pumping chamber to the spray
nozzle, means for adjusting the stroke of said piston pump to
control the quantity of spray medial pumped by said diaphragm pump,
and means bleeding oil from said sump between the piston pump and
diaphragm pump for replenishing oil leakage and for bleeding oil
back to the sump to accommodate a change in stroke of the
piston.
4. The spray gun of claim 1 including at least one oil intake port
opening to the interior of the cylinder at the upper dead center
position of the piston and converging toward the interior of the
cylinder to restrict backflow from the cylinder to the sump.
5. The spray gun of claim 1 wherein the piston pump has an upright
cylinder in the oil sump having converging ports accommodating flow
of oil from the sump into the cylinder head of the piston and to
accommodate flow of oil from the cylinder back to the sump at a
higher attenuation rate than the inflow to the cylinder.
6. The spray gun of claim 1 wherein the piston pump has a spring
biased piston engaging the oscillating armature of a vibrator motor
in the housing.
7. The spray gun of claim 2 wherein the diaphragm pump body is
composed of plastic and detachably secured to the bottom of the
head by fastener screws.
8. The spray gun of claim 2 wherein the diaphragm of the diaphragm
pump is clamped between a plastic pump body and a bushing
supporting the cylinder of the piston pump.
9. The spray gun of claim 3 wherein the cylinder of the piston pump
is supported by a bushing with a flange bottomed on the bottom of
the head and held against said bottom by the body of the diaphragm
pump whereby the pump bodies of both pumps are removable as a unit
from the head.
10. The spray gun of claim 3 wherein the electric motor in the head
is a vibrator with an oscillating armature, and a manual adjustment
means engages said armature to control the stroke thereof.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a portable spray gun for spraying
liquids, such as paints, which has a hydraulic piston pump driven
by an electric vibrator and in turn driving a diaphragm pump for
the liquid to be sprayed and isolating the liquid from the piston
pump. Specifically the invention deals with an electric vibrator
driven paint spray gun having an oil sump defining head housing an
electric vibrator and a piston pump that hydraulically drives a
diaphragm pump receiving paint from a container suspended from the
head and discharging to a spray nozzle with the spray rate
controlled by adjusting the stroke of the vibrator with an
adjusting screw carried by the head.
2. Description of the Prior Art
Electric spray guns generally have a piston pump directly
propelling the spray medium and exposed to this medium so that on
the compression stroke the fluid to be sprayed tends to penetrate
the gap between the piston and cylinder wall. Highly fluid spray
liquids will tend to escape through the cylinder past the piston to
the interior of the gun where they may possibly endanger the
operational safety as, for example, when penetrating the electric
motor. Thicker liquids to be sprayed, such as paints and varnishes,
will deposit abrasive pigments on the piston and cylinder wall
causing rapid wear and deterioration. To date no satisfactory
sealing between the piston and cylinder wall is available that is
capable of withstanding chemical and mechanical attack of the
liquids being sprayed, particularly paints and varnishes. The
leakage and wear problem is particularly acute in lightweight
portable spray guns where in the piston pumps must be quite small
and particularly sensitive to leakage and clogging.
SUMMARY OF THE INVENTION
According to the present invention, the sealing and wear problems
of prior known piston pump spray guns is eliminated by completely
isolating the piston pump from the spray media. This is
accomplished by pumping the spray media with a diaphragm exposed on
one side to the spray media and on the opposite side to a hydraulic
piston pump submerged in an oil sump and driven by an electric
vibrator. On the suction stroke the diaphragm draws the spray media
into a valved chamber on one side thereof. At the end of the
suction stroke the chamber is closed to trap the spray medium
therein. On the compression stroke the diaphragm propells the
trapped medium to the spray nozzle. The opposite side of the
diaphragm is propelled by oil from the sump trapped ahead of the
piston. The piston is driven by the oscillating head of an electric
vibrator and its stroke is adjusted by controlling the stroke of
the vibrator head.
Since the diaphragm completely isolates the spray medium from the
piston pump and since it has no wearable parts sliding on each
other the desired operating safety and long life of the spray gun
is assured even though the spray medium may contain highly abrasive
material.
Since the delivery capacity of the diaphragm is a function of the
stroke of the piston as well as the amount of oil trapped between
the piston and the diaphragm on the pressure stroke of the piston,
leadage of such trapped oil is replenished through ports which,
however, accommodate restricted backflow so that a reduced volume
of trapped liquid can be established to permit a reduced stroke of
the piston. The piston drives the diaphragm through the oil trapped
between the piston and diaphragm, but uncovers the ports at its top
dead center position so that leakage may be replenished to maintain
a full oil charge ahead of the piston on its pressure stroke when
the stroke is maintained constant. When the stroke is lessened,
however, the excess trapped oil may be relieved through these
ports. The port passages converge toward the interior of the
cylinder in a manner to accommodate flow into the cylinder while
restricting flow out of the cylinder.
A feature of the invention includes the provision of an oil sump in
the head of the spray gun which houses the electric vibrator motor
and the piston pump. Since the diaphragm pump is relatively free
from wearable parts, its body may be made of plastic and secured to
the bottom of the head with the diaphragm clamped in position and
the entire assembly secured to the head by screws. The body of the
piston pump is preferably held by a flange clamped between the
bottom of the head and the body of the diaphragm pump so that both
pump bodies are removable as a unit from the pump head. The
diaphragm body carries an inlet valve receiving the pumping media
from a container suspended from the head and also mounts the outlet
nozzle carrying an outlet valve.
It is then an object of this invention to provide an inexpensive
lightweight portable spray gun having a head defining an oil sump
and mounting an electric vibrator motor and a hydraulic piston pump
driven by the motor which in turn drives a diaphragm pump suspended
from the head and isolating the pumping media from the piston pump
and oil sump.
Another object of this invention is to provide a lightweight
portable paint spray gun with a piston pump which hydraulically
drives a diaphragm pump separating the pumping media from the
piston pump.
A further object of this invention is to provide an electric spray
gun with a piston pump hydraulically driving a diaphragm pump for
the spray media.
A specific object of the invention is to provide an electric spray
gun having a hydraulic piston pump driven by an electric vibrator
and in turn driving the diaphragm communicating on one side with
the piston pump and on the other side with the spray media and
having ports in the piston pump accommodating flow of hydraulic
fluid ahead of the piston so that the stroke of the piston may be
changed to vary the pumping rate of the diaphragm pump.
A specific object of this invention is to provide a lightweight
inexpensive electric spray gun with a hollow head providing an oil
sump and housing an electric vibrator motor and a piston pump
driven thereby and suspending a diaphragm pump driven by the piston
pump which effects the pumping of the spray media and having a
cover closing the head carrying a screw control for regulating the
stroke of the vibrating motor to thereby control the stroke of the
piston pump.
Other and further objects of this invention will become apparent to
those skilled in this art from the following detailed description
of the annexed sheet of drawings which by way of a preferred
example illustrates one embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWING
The single FIG. 1 of the drawing is a vertical cross-sectional
view, with parts in elevation, of the head portion of a spray gun
of this invention and partially illustrating the handle of the gun
and the container for the spray medial suspended from the head.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The spray gun shown in the drawing includes a housing head 1 closed
by a lid 2 and mounting an electric vibrator motor having a stator
3 with magnetic coils 4 and a pivot 5 for a vibrating head or
oscillating armature 6. The armature 6 drives a piston pump with a
piston 7 slidable in an upright cylinder 8 and biased against the
armature 6 by a spring 9.
A diaphragm pump is suspended from the head 1 and includes a
diaphragm 10 clamped between a bushing 11 and the pump body 12. The
diaphragm 10 separates the chamber provided by the bushing 11 and
the pump body 12 into an oil area or sump 13 and an underlying
pumping chamber or area 14 for the spray media to be pumped.
A spring 15 in the pump body 12 biases a plate 16 against the
underface of the diaphragm 10 to spring-load the diaphragm against
the oil in the sump 13.
An inlet valve 17 biased to a closed position by a valve spring 18
is mounted under the diaphragm 10 and spring plate 16 being
supported in the housing 12 by a threaded nipple 19 with a
depending stud receiving the inlet tube 20 for the spray media. The
tube 20 may communicate either with a separate paint container or,
as shown, to a container 21 suspended under the housing head 1.
An outlet channel 23 communicates with the diaphragm or pumping
area 14 and discharges through a valve 24 to the spray nozzle
25.
Channels or ports 26 are provided in the cylinder 8 of the piston
pump to replenish oil which might leak out of the pump as well as
to regulate the quantity of oil trapped ahead of the piston 7 when
the stroke of the piston is changed. The cross-sectional area of
the channels 26 is gradually tapered toward the interior of the
cylinder 8 to provide for relatively free flow through the channels
into the cylinder but to restrict or attenuate flow from this
cylinder. The channels 26 are located at a level in the cylinder 8
so as to be uncovered at the upper dead center position OT of the
piston 7.
The stroke of the piston 7 is adjusted by a set screw 27 threaded
in the lid 2 and engaging a leaf spring 28 having one end anchored
to the lid and the other end bottomed on the free end of the
oscillating armature 6 above the piston. Threading of the screw 27
into the lid will load the leaf spring 28 more tightly against the
oscillating head 6, thereby restricting its travel.
A handle 30 is suspended from the head 1 by means of screws or the
like and carries a push-button 31 controlling current flow through
electric conduits energizing the coil 4.
The entire interior area 32 of the housing 1 is filled with oil so
that the cylinder 8 of the piston pump is completely immersed in
oil.
The cylinder 8 of the piston pump is held in upright position in
the housing 1 by the bushing 11 which has a flange 33 with one side
bottomed on the floor 34 of the housing head and the other side
bottomed on the pump body 12. Screws indicated at S secure the pump
body to the floor 34 of the head 1 and clamp the diaphragm 10
between the pump body and the bushing flange 33. The bushing 11 in
turn carries the cylinder 8. Thus, both the piston pump and the
diaphragm pump form, together with the inlet valve 17, a unit
secured to the bottom of the head 1 by the screws S which can be
assembled or disassembled for service or replacement of parts. The
pump body 12 may be composed of plastic.
OPERATION
During the downward movement of the piston 7 caused by the
oscillating armature 6, the ports 26 of the sleeve 8 are first
closed so that the oil ahead of the piston will act on the
diaphragm 10 to drive the diaphragm downwardly against the spring
biased plate 16. This downward movement of the diaphragm decreases
the area 14 and propells the spray media therein to the nozzle 25
through the channel 23 and the valve 24.
During the subsequent upward movement of the piston 7 which is
accomplished by the bias of the spring 9, the diaphragm 10 is urged
upwardly by the spring biased plate 16 enlarging the pumping area
14 and creating a reduced pressure therein sufficient to open the
inlet valve 17 against the spring load 18 and aspirating the
spraying media into the pumping chamber 14 via the inlet tube
20.
If the upward stroke of the piston 7 is sufficient to uncover the
ports 26 in the cylinder 8, oil will flow from the sump 32 to
replenish any oil lost by leadage, for example, through the gap
between the piston and cylinder during the preceding downward or
pressure stroke so that with an unchained setting of the adjustment
screw 27 a uniform delivery of the diaphragm pump is
maintained.
If the delivery of the diaphragm pump is to be changed, for example
increased, the set screw 27 is turned upwardly so that the upper
dead center OT of the piston 7 will be at a higher level in the
cylinder 8. This increases the area ahead of the piston so that
during the upward movement of the piston oil is aspirated through
the ports 26 from the oil sump 32. Due to the tapered design of the
ports 26, the amount of oil flowing back to the sump during the
subsequent pressure stroke of the piston 7 prior to the piston
covering the ports 26 will be much smaller than the amount of oil
previously aspirated into the cylinder. Thus, a greater volume of
oil will be trapped ahead of the piston to fill the increased area
provided by the increased stroke of the piston. This in turn
increases the stroke of the diaphragm 10 and in turn increases the
pumping rate of the diaphragm pump.
It will be understood from the above descriptions that this
invention now provides an improved spray gun which completely
separates the spraying media from the pumping mechanism and
conveniently houses an electric motor driven piston pump in an oil
sump provided by the head of the gun while suspending a diaphragm
pump for the pumping media from this head.
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