U.S. patent number 3,797,534 [Application Number 05/111,720] was granted by the patent office on 1974-03-19 for power operated means for filling aerosol cans.
This patent grant is currently assigned to Sprayon Products Inc.. Invention is credited to Richard H. Skidmore.
United States Patent |
3,797,534 |
Skidmore |
March 19, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
POWER OPERATED MEANS FOR FILLING AEROSOL CANS
Abstract
An apparatus and method for filling aerosol cans containing a
liquid propellent with a material to be dispensed in which a power
operated piston is employed to force the material into the aerosol
can through a discharge valve of the can. A substantially uniform
force is applied to the piston to insure that essentially uniform
quantities of material are injected into the can with each stroke
of the piston.
Inventors: |
Skidmore; Richard H.
(Lyndhurst, OH) |
Assignee: |
Sprayon Products Inc. (Bedford
Heights, OH)
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Family
ID: |
22340095 |
Appl.
No.: |
05/111,720 |
Filed: |
February 1, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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803665 |
Mar 3, 1969 |
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Current U.S.
Class: |
141/3; 91/26;
91/396; 141/20; 141/261 |
Current CPC
Class: |
B65B
31/003 (20130101) |
Current International
Class: |
B65B
31/00 (20060101); B65b 003/12 () |
Field of
Search: |
;141/3,20,258,259,260,261,262 ;91/26,396 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bell, Jr.; Houston S.
Attorney, Agent or Firm: Bosworth, Sessions & McCoy
Parent Case Text
REFERENCE TO RELATED APPLICATION
This is a continuation of application Ser. No. 803,665, filed Mar.
3, 1969, now abandoned.
Claims
What is claimed is:
1. Apparatus for charging material to be sprayed into a pressurized
aerosol can having a valve and containing a liquified propellant
gas, comprising a reservoir having a sufficient capacity for said
material to charge a plurality of said aerosol cans, said reservoir
having an operating bore provided with a connecting portion adapted
to make a sealed communicating connection with the valve of said
aerosol can, a piston member mounted for reciprocation in a working
direction and a return direction in said operating bore and
effective upon reciprocation in the working direction to force said
material through said connecting portion and aerosol valve into
said can against the pressure of the liquified gas, fluid
pressure-actuated means for reciprocating said piston member in
strokes of substantially equal length, and means for supplying
fluid under a substantially constant pressure to said
pressure-actuated means, whereby said fluid pressure-actuated means
applies a substantially uniform force to said piston member during
the reciprocation thereof in the working direction, and whereby the
amount of material injected during each working stroke of the
piston is substantially the same and each of said plurality of cans
is substantially equally filled by substantially the same number of
strokes of said piston member, regardless of the viscosity of said
material.
2. The apparatus of claim 1 wherein said fluid pressure-actuated
means is a double-acting, pneumatic cylinder and piston
combination.
3. The apparatus of claim 1 wherein said operating bore has a
cross-sectional configuration substantially matching that of the
piston member to provide a working fit, and said fluid
pressure-actuated means provides a length of stroke for the piston
member sufficient to clear the operating bore on its return stroke
to permit the reservoir to fill the bore.
4. The apparatus of claim 3 including means to decelerate the
reciprocation of the piston member during a back stroke after
clearing said operating bore to allow proper fill of the bore from
the reservoir prior to a succeeding forward stroke of the piston
member.
5. The apparatus of claim 3 wherein said operating bore and piston
member are free of any seal therebetween.
6. The apparatus of claim 3 including an aerosol can and wherein,
in effecting said sealed communicating connection between said
connecting portion and can, one of the sealing parts is resilient
plastic and the other is metal.
7. The apparatus of claim 1 including counter means, and means
responsive to the reciprocation of the piston member to actuate the
counter means, said counter means being adapted to stop said
reciprocation of the piston member upon reaching a predetermined
count.
8. The apparatus of claim 1 wherein said operating bore has a
cross-sectional configuration substantially matching that of the
piston member to provide a working fit, said connecting portion has
check valve means normally preventing release of said material
therethrough but adapted to be opened in effecting said sealed
communicating connection with the can.
9. The apparatus of claim 1 wherein the length of the stroke of
said piston member is substantially constant.
10. Apparatus for charging material to be sprayed into a
pressurized aerosol can having a valve and containing a liquified
propellant gas, comprising a reservoir having a sufficient capacity
for said material to charge a plurality of said aerosol cans, said
reservoir having an operating bore provided with a connecting
portion adapted to make a sealed communicating connection with the
valve of said aerosol can, a piston member mounted for
reciprocation in said operating bore and effective upon
reciprocation to force said material through said connecting
portion and aerosol valve into said can against the pressure of the
liquified gas, said piston member and bore having a clearance
therebetween to avoid a complete sealing action while providing a
working fit, fluid pressure-actuated means for reciprocating said
piston member repeatedly through working and return strokes of
substantially the same length to fill one of said plurality of
cans, and means for maintaining a substantially constant fluid
pressure on said pressure-actuated means, whereby a substantially
constant force is exerted on said piston member, and whereby each
of said plurality of cans is substantially equally filled by
substantially the same number of strokes of said piston member,
regardless of the viscosity of said material.
11. A process for charging material to be sprayed into a
pressurized aerosol can having a valve and containing a liquified
propellant gas, comprising:
a. disposing a reservoir of said material having a reciprocable
piston member in communicating connection with said can,
b. reciprocating said piston member by fluid pressure-actuated
means through a working stroke and a return stroke to force said
material from the reservoir into said connection and through the
aerosol valve into said can against the pressure of said liquified
gas,
c. maintaining a substantially constant fluid pressure on said
fluid pressure-actuated means during its reciprocation of the
piston member to apply a substantially constant force on said
piston during its working stroke and fill substantially equally a
plurality of said cans by substantially the same number of strokes
of the piston member regardless of the viscosity of said material,
and
d. continuing to reciprocate said piston member until the can is
filled to a desired extent.
12. The process of claim 11 wherein said reciprocation of the
piston member is decelerated during a backward stroke away from
said communicating connection to allow proper fill thereof for a
succeeding downward stroke of the piston member.
13. The process of claim 11 wherein said piston member is
reciprocated through strokes of substantially the same length.
Description
BACKGROUND OF THE INVENTION
This invention relates to an apparatus and method for injecting
material to be sprayed into aerosol cans and, more particularly, to
an apparatus and method for injecting material such as paints,
enamels, lacquers and the like into Aerosol cans that contain
liquified propellent gas, such as dichlorodifluoromethane under
pressure, and a solvent for the material to be sprayed.
In U.S. Pat. No. 3,335,765, issued Aug. 15, 1967, and in
application, Ser. No. 640,765, filed Mar. 29, 1967, in the name of
William Moonan, now U.S. Pat. No. 3,430,819 both of which are owned
by the assignee of the present invention, a method and apparatus
and article for packaging of aerosol products are disclosed and
claimed. According to the disclosure of said patent and
application, it is possible economically and efficiently to fill
small numbers of aerosol cans with specially blended or formulated
materials, such as paints and the like, that are blended to match a
customer's requirements as to color. This is accomplished by
providing aerosol cans of conventional type having an aerosol
discharge valve at the top. These cans are filled at the factory
with sufficient liquified propellent gas to discharge the contents
of the can and with a solvent for the material to be sprayed
sufficient to reduce the material to proper spraying viscosity or
consistency. The cans are completed by or for the ultimate user by
placing the can in an apparatus of the type disclosed, for example,
in U.S. Pat. No. 3,335,765, and by hand pumping the required
quantity of the material to be sprayed into the can against the
pressure of the propellent gas within the can and through the
aerosol discharge valve.
The article, method and apparatus of the aforesaid application and
patent have been extremely successful and are widely used. It has
been found, however, that many users of the inventions of
theaforesaid patent and application find it desirable to fill not
just one or two aerosol cans with a particularly custom blended
color of paint, for example, but sometimes as many as 25 or even 50
cans with the same kind of paint. Also, some users fill
comparatively large numbers of cans with either the same or
different kinds of paint in a given day. The hand operated pump or
apparatus of U.S. Pat. No. 3,335,765 then becomes tiring to use and
too slow in operation for economical use.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an
improved power operated apparatus and method for injecting material
to be sprayed into aerosol cans that contain the liquified
propellent gas required to discharge the contents of the can.
Another object is to provide an apparatus and method whereby the
quantity of material injected into the cans can be accurately
controlled so that reproducible results can be obtained for a
series of cans. Another object is to provide an apparatus that is
compact, reliable, easy to operate without requiring skill on the
part of the operator and reasonably economical to manufacture. A
further object is to provide a method and apparatus that operate to
inject substantially constant quantities of material into a can for
each stroke of the piston, regardless of substantial variations in
the viscosity of such material.
Briefly, according to preferred forms of the invention, these and
other objects and advantages of the invention are obtained by
providing an apparatus having means for supporting a can to be
filled in vertical position and a reservoir and cylinder member
also supported in the apparatus adapted to be positioned directly
above the can to be filled. The reservoir and cylinder member has a
reservoir portion of enlarged volume, a working bore in which a
piston reciprocates, and a reduced bore that is adapted to make
sealing engagement with the body of the discharge valve of the can
to be filled. A piston is reciprocated in the cylinder to force
material from the reservoir into the can. Preferably, the piston is
reciprocated by a fluid pressure cylinder that is arranged to exert
a substantially constant force on the piston during its working
stroke. As a result, the amount of material injected into an
aerosol can for each stroke of the piston is substantially
constant, regardless of the viscosity of the material being
injected into the cans. The piston simply moves more slowly for
materials of relatively high viscosity and more rapidly for
materials of relatively low viscosity.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings:
FIG. 1 is a side elevational view of a preferred form of apparatus
embodying the invention with parts broken away;
FIG. 2 is a vertical section to an enlarged scale illustrating a
preferred form of fluid pressure piston for operating the plunger
or piston of the apparatus;
FIG. 3 is a plan view partially in section to the same scale as
FIG. 1 and taken as indicated by line 3--3 of FIG. 1;
FIG. 4 is a view to a greatly enlarged scale, taken at right angles
to the corresponding part of FIG. 1, showing the engagement between
the lower part of the apparatus and the aerosol valve of a can
being filled;
FIG. 5 is a sectional detail showing the apparatus for holding the
aerosol can in position to be filled;
FIG. 6 is a front elevational view of an apparatus similar to that
of FIG. 1 but showing use of an automatic counter and modification
of the apparatus to fill a can of smaller size;
FIG. 7 is a diagram illustrating the fluid pressure control and
actuating components of one form of the invention; and
FIG. 8 is a similar diagram illustrating a modified form of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The apparatus of the present invention is particularly adapted to
inject materials into aerosol cans of conventional types, for
example, cans such as illustrated at 10 in FIG. 1 in place in the
apparatus for filling. Can 10 has a cylindrical body 11 that is
closed by a conventional bottom member and reduced in diameter at
the top as indicated at 12, leaving an opening closed by a closure
cap 13 that is crimped and sealed to the upper edge of the can body
(FIG. 4).
Cap 13 supports a discharge valve 14 that may take any convenient
form, a preferred form of valve being illustrated on an enlarged
scale in FIG. 4 and described in detail and claimed in U.S. Pat.
No. 3,182,864, issued Nov. 21, 1961, and owned by the assignee of
the present application. For the purposes of the present
application, it will suffice to say that the valve is composed of a
valve body 16 that is crimped to the closure cap 13 as shown at 17
and which has an internal bore 18 that communicates at its lower
end with a dip tube 19 extending to the bottom of the can. A valve
member 20 is disposed in the bore and is urged upwardly by a spring
21 into sealing engagement with a valve seat 22 that is formed into
the bore. The valve member is urged into sealing engagement with
the valve seat 22 not only by the spring 21 but also by the
pressure of the propellent gas within the spring. The valve is thus
in the nature of a check valve that is normally closed to prevent
discharge of the contents of the can, but which can be opened by
external fluid pressure in excess of the pressure within the can,
thereby permitting material to be injected into the can.
In FIG. 4 the valve member is shown as being displaced downwardly
away from the seat 22. This occurs when material is being forced
into the can. In practice a pressure of several hundred pounds per
square inch is required to open the valve and displace the valve
member 20 downwardly to the position shown in FIG. 4 against the
fluid pressure and the force exerted by the spring. The reason for
this, of course, is that the area of the valve member 20 exposed to
pressure of the material being forced into the can is relatively
small so that even though the spring pressure is not excessive, the
fluid pressure required to open the valve against the action of the
spring and the fluid pressure within the can is substantial.
It is to be noted that the exterior of the valve body 16 is
provided with an upper portion 25 of reduced diameter that is
connected to the lower portion of the valve body by a shoulder 26.
As explained below, this shoulder is utilized to provide a seal
between the filling apparatus and the valve. As supplied to the
user of the apparatus of the present invention, the cans 10 contain
sufficient propellent, ordinarily in the form of liquified
dichlorodifluoromethane, to discharge the complete contents of the
can and, in addition, contain a solvent that is compatible with the
liquified propellent gas and with the material, such as a paint or
the like, that is subsequently to be injected into the cans. After
the cans have been filled they are provided with actuating caps and
pins (not shown), so that the user by a finger pressure can move
the valve 20 out of contact with its seat, opening the valve and
permitting the contents of the can to be discharged in the form of
an aerosol spray. This is all as explained in the aforesaid patent
and application.
A typical 12 ounce aerosol can that is adapted to have a paint or
the like injected into it contains about 170 grams of
dichlorodifluoromethane and about 85 grams of solvent. To complete
the can as an aerosol package, about 85 grams of paint or the like
(this amount varies with the different materials) are injected into
the can through the valve 14. Since substantial pressures are
involved, it becomes a time-consuming and tiring task to fill a
series of cans or a substantial number of cans with the hand
operated apparatus of the aforesaid Moonan U.S. Pat. No. 3,335,765.
The present invention, therefore, is directed to a relatively
simple and economical power apparatus whereby accurately controlled
amounts of materials can be injected into pressurized aerosol cans,
preferably through the discharge valves thereof.
GENERAL ARRANGEMENT
Referring now to FIG. 1 of the drawings, a preferred form of
apparatus according to my invention comprises a base member 30 that
carries a can supporting platform 31 to be described below. The
base is hollow as shown and preferably takes the form of a casting.
The injecting apparatus is supported above the base, there being
two lower rear supporting posts 32 and two lower front supporting
posts 33. These posts support an intermediate plate 34 that carries
a reservoir and cylinder member, indicated in general at 35,
comprising a reservoir portion 36, a main operating bore 37, and a
connecting portion 38 that makes sealing engagement with the body
of the valve 14 of the aerosol can 10.
In order to removably support the reservoir and cylinder member 35
on the intermediate plate 34, the plate is provided with a key-hole
slot 39, and the connecting portion 38 of the member 35 is provided
with a groove 40 having flat portions 41 (FIGS. 1 and 3). The
cylinder member can thus be inserted into the key-hole slot 39 and
given a quarter turn, whereupon it is firmly secured in position.
Yet the cylinder member can be readily removed by turning it so
that the slots 41 are parallel to walls 42 of the key-hole slot
39.
The actuating mechanism for the apparatus is supported by a top
plate 43 that is carried by two rear upper posts 44 and two front
upper posts 45. The actuating mechanism comprises a fluid pressure
cylinder and piston combination, indicated in general at 46, having
a downwardly projecting piston rod 47 to which an injection piston
48 is secured. The cylinder and piston combination 46 reciprocates
the piston 48 from an upper position as shown in FIG. 1, where the
lower end 49 of the piston is substantially above the upper end 50
of the working bore 37 of the reservoir and cylinder member 35, to
a position as shown in dotted lines in FIG. 4, in which the end 49
of the piston is near the bottom of the working bore 37. As
explained more fully below, the cylinder is arranged so that it
always stops with the piston 48 in the upper most position.
The top plate 43 also supports a four-way pilot control valve 52, a
counter 53, and counter actuating cylinder 54 (FIG. 1). Actuating
fluid, which in the present instance may be air, is supplied by a
suitable air compressor C (FIG. 6) through a filter 55, pressure
regulator 56 having a gage 57, and a lubricator 58, to the four-way
pilot valve 52 through an appropriate control valve. The
components, which are of well known types and may be purchased on
the open market, are diagrammatically illustrated in FIGS. 7 and 8
and the functioning of the apparatus is described in conjunction
with these figures.
CAN SUPPORT
In order to support cans 10 in proper position for filling, the can
supporting platform 31 is provided with a circular flange 60 of
proper diameter to fit the bottom of the can 10 so that, when a can
is placed on the platform 31, it is properly centered with respect
to the reservoir and cylinder member 35. This member is accurately
located on the intermediate support 34 by the key-hole slot 39, so
that the working bore 37 is in alignment with the piston 48. In
order to provide for raising and lowering the platform and a can
mounted thereon, the platform is provided with a downwardly
extending plunger 61 that is slidably mounted for vertical movement
in a bore 62 formed in a boss 63 that is preferably cast integrally
with the base member 30.
The platform is raised and lowered by means of a toggle mechanism
of known type, indicated in general at 64, and having an actuating
handle 67 and an actuated lever 68. The handle 67 is shown in full
lines in the position it takes when the can is raised into
engagement with the reservoir and cylinder member 35; and in broken
lines in the position it takes when the platform and can are
lowered. It will be noted that pushing down on the handle 67 raises
the actuated lever 68. The end of the actuated lever 68 engages a
plunger 70 that is mounted for slidable movement in a bore 71 of
the downwardly extending plunger 61. The end of the plunger 71
engages a spring 72 within a reduced portion of the bore in the
plunger 61. The plunger 70 is retained within the bore 71 by a pin
70a that extends through the walls of downwardly extending plunger
61, there being clearance as shown in the plunger 70 around the pin
70a to permit spring 72 to urge the platform 60 resiliently. Thus
when the handle 67 is in its lower position, the force of the
spring 72 urges the can upwardly into engagement with the reservoir
and cylinder member 35. This insures proper engagement between the
valve members of the cans and the reservoir and cylinder member,
regardless of slight variations in the dimensions of the cans.
The toggle mechanism 64 is such that the handle remains in its
lower position shown in full lines against the force exerted on it
by the plunger 70, so that an operator needs only to push the
handle 67 downwardly to raise the can into engagement with the
connecting portion 38 of the reservoir and cylinder member 35,
where the can stays until the toggle mechanisms is released by
raising handle 67. Obviously, other mechanisms for raising and
lowering the platform may be employed, but it is desirable that a
resilient and locking mechanism of some type be used in order to
insure proper sealing engagement between the valve member of the
can and the connecting portion of the member 35, and to make it
unnecessary for the operator to hold the platform raising mechanism
in position during the operation.
The engagement between the valve member 14 of a can and the bottom
end of the reservoir and cylinder member 35 is shown particularly
in FIG. 4. As there indicated, the connecting portion 38 of the
reservoir and cylinder member is provided with an opening 73 having
a flared end that surrounds the larger diameter of the valve body
16. This portion terminates in an upwardly and inwardly extending
shoulder 74, that corresponds to shoulder 26 on the valve body, and
finally in a bore of reduced diameter 75 that receives the upper
portion 25 of the valve body. From the reduced diameter 75, the
bore is flared outwardly as at 76 to the diameter of the working
bore 37.
The valve body 16 consists of a resilient plastic, for example
polyethylene, so that in seating against the connecting portion 38,
there is an effective seal between the plastic shoulder 26 and the
metallic shoulder 74.
In order to prevent leakage of paint or the like from the reservoir
and cylinder member 35 when no can is present, a ball check valve
79 is provided. When a can is present in the apparatus, as shown in
FIG. 4, the ball is lifted above the bore 75 by the upper end 25 of
the valve of the can. In this position ball 79 does not impede flow
of material into the bore of the valve and thence into the can.
However, when the can is removed from the apparatus, and at any
time that there is no can in position in the apparatus, the ball 79
drops to the bottom of the portion defined by the enlarged wall 76
and seats at the top of the bore 75. This effectively prevents
leakage of paint during the time that one can is being removed from
the apparatus and another can inserted in it.
INJECTION MECHANISM
As noted above, the injection piston 48 operates in the working
bore 37 of the reservoir and cylinder member 35. The reservoir and
cylinder member must be accurately constructed in order that the
working bore 37 will be properly aligned with the piston 48, and so
that the connecting portion 38 and bore 73 will be properly aligned
with the valve 14 of a can positioned on platform 31. To this end,
the lower portion of the member 35 preferably consists of a lower
member 85 and an annular member 38 that is secured to the lower
member as by copper brazing of the contact surfaces at 87.
The lower member 85 is accurately machined from steel, and the
groove 40 and slots 41 (FIG. 3) are formed to fit accurately the
Arcuate portions of the key-hole slot 39 when the cylinder member
is in position in the intermediate supporting plate 34. The working
bore 37 and the connecting portion 38 and its bores are also
accurately machined, so that when the reservoir is in position in
the intermediate plate 34 correct alignment is assured.
In order to provide an accurate and long-wearing working bore for
cooperation with the injection piston 48, the working bore is
carefully machined and the bore is provided with a hard chrome
plating that is finally finish-ground to very close tolerances. The
reservoir portion 36 of the member 35 preferably is constituted by
a section of tubing that removably engages the cylindrical portion
or surface 89 of the upper member 86, an O-ring seal 90 being
provided to prevent leakage between the cylinder 36 and the member
86.
Since paints and the like that are injected into the can by the
apparatus frequently contain pigments of an abrasive character, no
attempt has been made to provide a completely leak-proof seal
between the piston 48 and the bore 37 in which it reciprocates.
Instead, piston 48 and its connection to the piston rod 47 of the
cylinder 46 are accurately machined so that, with the cylinder 46
accurately positioned on the top plate 43 and the reservoir and
cylinder member 35 accurately located by the intermediate plate 34,
the axes of the piston and the working bore 37 will be
substantially coincident. Also, the piston is accurately machined
and the working portion of its hard chrome-plated and ground to
tolerances, such that the clearance between the piston and the bore
37 does not exceed about 0.0005 inch. With this clearance there can
be a small amount of leakage between the piston and cylinder, the
leakage does not appreciably affect the consistency of the amount
of material injected into the cans for each stroke of the piston,
even with materials of widely varying viscosity characteristics and
under different temperature conditions. As explained in greater
detail below, this is probably because the actuating cylinder and
piston 46 exert a substantially constant force on the piston 46 in
the working direction. Also, large numbers of cans can be filled
with paints and the like without substantial wear or sufficient
wear on either the piston 48 or the working bore 37 to affect the
accuracy of the operation.
The embodiment of FIG. 6 is similar to that of FIG. 1, and similar
parts have been given like reference numerals. The apparatus of
FIG. 6 differs from that of FIG. 1 in basically two respects. For
one, the top plate 43 supports an automatic counter 59 instead of
the counter 53 and counter actuating cylinder 54. Counter 59 is of
the type arranged to open a valve upon a pressure pulse and is
described more fully in conjunction with the description of the
schematic flow diagram of FIG. 8 which is adapted for use with
apparatus of the type illustrated in FIG. 6. FIG. 6 also
illustrates the adaption of the apparatus for filling cans of
smaller size than that illustrated by FIG. 1. A cylindrical spacer
15 has a small annular projection 23 at its bottom to seat upon the
platform 31, the circular flange 60 of the platform engaging and
resisting lateral movement of the projection 23. At its upper end,
spacer 15 has a flange 24, so that this end matches in
configuration the upper surface of platform 31 and can similarly,
securely support a can 11a which, as indicated, is of smaller size
than can 11 of FIG. 1.
FLUID PRESSURE SYSTEM
As mentioned above, the injection piston 48 is reciprocated by a
fluid pressure cylinder and piston combination 46 from the full
line position shown in FIG. 1 to a point where the end 49 of the
piston is near the lower end of the working bore 37 and slightly
clears the ball check valve 79 as shown in broken lines in FIG. 4.
Preferably, cylinder 46 is an air cylinder and of a known type
controlled by pilot valves at each end of the cylinder in
conjunction with the four-way pilot operated valve 52. Cylinders
and valves of this type are well known, suitable components of this
type being available from Mead Specialities Co., Inc. of Chicago,
Ill., and illustrated in that company's Bulletin DM-1. The cylinder
46 is arranged to reciprocate its piston rod 47 and piston 48
continuously, so long as air under pressure is supplied to the
system, and to stop only when the piston 48 is at the uppermost
position of its stroke, as indicated in FIG. 1.
The diagram constituting FIG. 7 illustrates a suitable arrangement
consisting of well known components. As there illustrated, air
supplied by a compressor C first passes through filter 55 to
regulating valve 56, the output pressure in the line leaving the
regulating valve being indicated by gage 57. The air passes through
a lubricator 58 where a spray of lubricant is added to the air to
furnish lubrication for cylinder 46. From the lubricator 58, a main
supply conduit 111 leads to the four-way pilot operated vlave 52
and to the pilot valves at the opposite ends 91 and 92 of the
cylinder 46. Operation of the system is controlled by a normally
closed foot pedal operated valve 93. When this valve is opened, air
under pressure at the upper end 92 of the cylinder 46 is permitted
to flow through the internal pilot valve at the end of the cylinder
to the pilot operated valve 52. From the valve 52 in this position,
air under pressure flows through conduit 95 to the upper end 92 of
cylinder 46. At the same time air is admitted through conduit 120
to the counter actuating cylinder 54 which is actuated against a
force of an internal spring 104. This in turn actuates the counter
53. The piston 46a of cylinder and piston combination 46 then moves
downwardly for the working stroke of the piston 48, until the
piston 46a reaches the lower end 91 of the cylinder.
When this occurs, the air connections to the cylinder 46 are
reversed. This is accomplished by an internal pilot valve at the
lower end of the cylinder that is actuated to permit control air to
flow through a conduit 98 to an actuating cylinder schematically
represented at 99 of the four-way valve 52. The cylinder reverses
the position of the valve 52, so that operating air under pressure
is now admitted through a conduit 101 to the lower end 91 of the
cylinder, while air is exhausted through conduit 95 and the quick
exhaust valve 102 at the upper end 92 of the cylinder.
If the operator takes his foot from the foot-controlled valve 93,
the piston 48 still completes its cycle but stops at the upper end
of its stroke. However, as long as the valve 93 is maintained open,
the piston continues to reciprocate in the cylinder 46, reversing
the connections when the piston reaches the top of its stroke, so
that air is admitted to the upper end of the cylinder 99 through
conduit 106 and 107 and the valve 93, reversing the position of the
pilot valve 52 and causing operating air under pressure to be
admitted through conduit 95, while the air beneath the piston 46a
(FIG. 2) exhausts through conduit 101 and valve 52 and its exhaust
port 108. When the operator removes his foot from valve 93, as at
any point during a cycle when the required number of strokes, as
determined by the counter 53, have been initiated, valve 93 opens
to the atmosphere through an exhaust port 94, and the piston
completes its entire cycle and stops at the upper end of its
stroke.
A slightly modified circuit is illustrated in FIG. 8 in which an
automatic counter is provided. Parts similar to those in FIG. 6
have been indicated by like reference numerals. The automatic
counter indicated at 59 is of a known type and arranged to open a
valve upon a pressure pulse and then to shut the valve after it has
received a predetermined number of pressure pulses. In this
arrangement, the operator momentarily depresses a push button
control valve 112, starting automatic counting control valve 58.
This closes the valve, depressurizing line 113 and the normally
open pilot operated, three-way valve 114 then opens. This valve 114
corresponds in function to the foot operated valve 93 of the
schematic flow diagram shown in FIG. 7 and, when depressurized
permits control air to flow through the conduit 115 to the upper
end of cylinder 99. This initiates the sequence of events that
causes the piston automatically to reciprocate as described for the
flow diagram of FIG. 7. When piston 46a (FIG. 2) reaches the bottom
of its stroke and the operating air under pressure is admitted
through conduit 101, air under pressure then is supplied through
conduit 116 to valve 112, thereby furnishing a pulse of air to the
counting control valve 59. Thus, each time that the piston 48
reverses its direction at the bottom of its stroke, a pulse is
furnished to the counter and valve control 59. The pulses are
automatically counted, and when a predetermined number of pulses
has been reached, the three-way valve 114 is pressurized, closing
the supply of air to cylinder 99, whereupon piston 46a completes
its cycle and stops at its uppermost position.
In a typical apparatus, the diameter of the cylinder 46 is 3.25
inches and its stroke is 2 inches. The diameter of the piston 48 is
0.75 inch. The area of the cylinder, therefore, is about 18.2 times
the area of the piston 48. Thus, the pressure developed by piston
48 in the material being injected into a can is about 18.2 times
the air pressure within the air cylinder 46. In a typical
installation, the pressure regulator valve 56 is set for 60 pounds
per square inch gage, and the air leaving the regulator is
maintained substantially constant at this pressure. There is, of
course, a drop in pressure as the air flows through the conduits
and valves into the cylinder 46. The actual operating pressures
within the cylinder are estimated to vary between 50 and 55 pounds
per square inch with the pressure regulator set for 60 pounds per
square inch. Variations of this character are considered to be
within the meaning of the term "substantially constant" as the
expression is sued in this specification and the claims.
Because viscous materials offer more resistance to flow than
materials of less viscosity, the piston operates more slowly on its
downward stroke with materials of great viscosity and, for this
reason, the flow of air in the conduits is slower, the pressure
drop is less, and the pressure within the cylinder is greater by a
relatively small amount with materials of greater viscosity than
with materials of lesser viscosities. For example, in a typical
apparatus with the range of pressures specified, the pressure
applied to the material being injected may vary from about 910 psi.
for relatively thin materials to as much as 1010 psi. for very
viscous materials. This automatic application of a slightly greater
pressure with more viscous materials is advantageous in reducing
the cycling time and presents no difficulties in the operation of
the apparatus. Even though the piston always moves in the upward
direction at the same velocity, since this is not affected by the
viscosity, the more viscous materials may require as much as five
times as many seconds per cycle as the thinner, less viscous
materials. The automatic slowing down of the piston with more
viscous materials is advantageous, because it prevents undue strain
from being placed on the apparatus and results in uniformity and
consistency in the amount of material injected for each stroke of
the apparatus.
It is to be noted that after the bottom end of the piston 49 clears
the top of the working bore 37 and goes beyond the orifice 50, the
material to be sprayed must flow into and fill the bore 37 before
the piston enters the bore on its next stroke. In order to give the
material, which may be quite viscous, time to do this without
slowing down the entire return stroke, the cylinder 46 and piston
46a are preferably constructed as shown in FIG. 2 with a cushion
arrangement of a well-known type that slows down the movement of
the piston as it approaches the upper part of its stroke. This is
accomplished by providing the upper part of the piston with a
projecting collar 120 that enters a recess 121 in a cylinder head
122 as the piston approaches the top end of its stroke, thus
closing a main exhaust port 124 and permitting the air ahead of the
piston to exhaust only through a restricted passageway 125 that is
controlled by a needle valve 126.
Thus, the retracting movement of the piston is slowed after the
lower end of the piston clears the top of the working bore 36 to
provide time for material to flow into the working bore. A check
valve 127 permits air to flow into the main part of the cylinder on
the succeeding down stroke of the piston, so that the down stroke
is not slowed by the presence of the cushion. This cushion
arrangement is well-known construction that, per se, forms no part
of the present invention. However, it is particularly useful in the
present apparatus, since it enables the piston to be slowed
sufficiently give time for the paint to run into the main operating
bore without affecting the rate of speed of the advance of the
piston or of the major portion of the withdrawal stroke of the
piston. Thus, the time required for a complete cycle of the piston
is substantially less than it would be if the entire return stroke
of the piston has to be slowed sufficiently to give time for the
material to run into the operating bore 37.
SUMMARY OF OPERATION
In operation, assuming the compressor C to be delivering the
required air under pressure, an operator has only to pour the
estimated amount of specially blended paint or the like into the
reservoir and cylinder member 35. The ball check valve 79 prevents
any of the material from flowing out of the bottom of the reservoir
and cylinder member whenever there is no can in position to be
filled.
The operator then places a pre-charged can containing propellant
and solvent upon the platform 31, if he is filling 16 ounce cans.
If he is planning to fill 12 or 6 ounce cans, he uses the
appropriate spacer 15 (FIG. 6) to raise the can to proper position.
The can is automatically centered by the flange 60 or 24 on the
edge of the platform or spacer, as the case may be. The operator
then depresses the handle 67, raising the can firmly into
engagement with the connecting portion 38 of the reservoir member,
the toggle mechanism retaining the can in position. If he is
operating a manually controlled machine, with a system as shown in
FIG. 7, the operator simply checks to see that the counter is in
the zero position, then steps on the pedal actuated valve 93 and
retains the valve in open position until the required number of
strokes have been made.
The operator knows the number of strokes required on the basis of
past experience or on the basis of data furnished by the
manufacturer. In a typical apparatus and with a paint or the like
of ordinary specific gravity, each stroke of the piston 48 injects
approximately eight grams of paint or the like into the can. From
the information furnished by the paint manufacturer or the
manufacturer of the precharged aerosol cans, the operator can
determine the number of grams of paint that should be injected into
a can of a given size and from this determine the number of strokes
of the piston that are required.
After the given number of strokes have been made, the operator
removes his foot from the pedal operated valve 93, raises the
handle 67 to lower the platform 31, and removes the can from the
apparatus. It is advisable to check to see that the correct amount
of paint has been injected by shaking the can, placing an actuating
cap and pin on the aerosol valve, discharging the paint that may be
in the dip tube 19, and then test spraying a small area. From the
behavior of the paint, the operator can readily determine whether
more or less paint should be injected into the can or whether the
amount initially employed was correct. After a little experience
the operator can determine readily whether one or two or a few
strokes more or less should be used. He then fills another can,
checks it in a like manner if deemed necessary, and then proceeds
to complete the order, replenishing the reservoir as required and
simply inserting precharged cans and removing filled cans after the
required amount of paint or the like has been injected into them.
Ultimately the cans are completed by installing actuating caps and
pins on the valves.
With the automatic counter 59 shown in FIG. 8, the operator
performs all of the steps outlined above except that instead of
utilizing a foot pedal and a counter, he simply sets the automatic
counter and momentarily depresses the button control valve 112. The
machine then proceeds to make the required number of strokes and
turn itself off. The operator can be doing something else while the
paint or the like is being pumped into the cans; it being necessary
for him only to remove the filled can and insert a new can at the
appropriate time. This is advantageous where fairly large numbers
of cans are to be filled and it is also advantageous where viscous
materials are employed because, while a cycle of reciprocation of
the pump for fairly thin paints and the like may take only two
seconds, a cycle for some very thick materials may require as much
as ten seconds. Thus, with some materials several minutes will be
required to inject the required amount of material into each can.
It becomes tedious and expensive for the operator to be required to
attend the machine during all the time that it is operating.
As noted above, the accuracy and consistency of amounts of material
injected by the machine is remarkable. This is probably because of
the fact that while the working pressure increases somewhat with
more viscous materials, the reduction in speed of the piston 48 on
its working stroke still gives the viscous materials time to flow
through the valve and tip tube into the can without building up the
pressure sufficiently to cause substantial leakage between the
piston 48 and the working bore 37. While there is more time for the
viscous materials to leak past the piston during working strokes,
the leakage apparently is approximately constant, because the
viscous materials do not have as great a tendency to leak as the
thinner materials. Whatever the reason, the volume of material
injected for each stroke of the piston remains remarkably
consistent, enabling the operator to obtain predictable and
repeatable results with the apparatus and resulting in the
production of aerosol cans of paint or the like having proper
consistency for spraying.
For instance, in one series of ten cans of 12 ounce capacity, ten
strokes of the apparatus were made to fill each can. Each fill
required about 28 to 30 seconds. Of the 10 cans, eight had a net
weight of 82 grams of paint, and the other two had a net weight of
81 grams.
While the foregoing describes several embodiments, it is understood
that the invention may be practiced in still other forms.
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