US3797534A

US3797534A - Power operated means for filling aerosol cans

Info

Publication number: US3797534A
Application number: US00111720A
Authority: US
Inventors: R Skidmore
Original assignee: Sprayon Products Inc
Current assignee: Sprayon Products Inc
Priority date: 1971-02-01
Filing date: 1971-02-01
Publication date: 1974-03-19
Anticipated expiration: 1991-03-19

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.

Description

United States Patent 1 Skidmore [4 1 Mar. 19,1974

[541 POWER OPERATED MEANS FOR FILLING 3.273.606 9/1966 O'Neill 141/20 AEROSOL CANS 3,338,022 8/1967 Moonan et a1 141/20 [75] lnventor: Richard H. Skidmore, Lyndhurst,

Ohm Primary Examiner-Houston S. Bell, Jr. [73] Assignee:- Sprayon Products Inc., Bedford Attorney, g Firm|30SW0r1h, SeSSiOIIS &

Heights, Ohio McCoy [22] Filed: Feb. 1, 1971 [21] Appl. No.: 111,720 [57] ABSTRACT Related U.S. Application Data a [63] Continuation of Ser NO 803 665 March 3 1969 An apparatus and method for filling aerosol cans conabandoned taining a liquid propellent with a material to be dis- I pensed in which a power operated piston is employed [52] us CL I U 144/3 91/26 91/396 to force the material into the aerosol can through a 4 l 1 {41/20 discharge valve of the can. A substantially uniform [511' Cl B65b 7 force is applied to the piston to insure that essentially ['58] Fie'ld 5 260 uniform quantities of material are injected into the 141/261 1 can with each stroke of the piston.

[56] References Cited 13 Claims, 8 Drawing Figures UNITED-STATES PATENTS 2.989.993 6/1961 Osmond et al 141/20 zzz-c PATENTEDMAR 19 1914 3.797; 534

sum 1 or 5 f7 INVENTOR.

Ema/0 Im /W025 gym! 45%,

ATTORNEYS.

memmm 1 9 m4 3791.534

SHEET 3 OF 5 A TTOEA/[KS POWER OPERA-TED MEANS FOR FILLING AEROSOL CANS REFERENCE TO RELATED APPLICATION This is a continuation of application Ser. No. 803,665, filed Mar. 3, 1969, now abandoned.

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. l5, 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 customers 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 justone 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. I and taken as indicated by line 33 of FIG. 1;

FIG. 4 is a view to a greatly enlarged scale, taken at right angles to the corresponding part of FIG. I, 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. l 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 has a cylindrical body Ill 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 US. 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 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 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 US. 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 keyhole 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 5S, 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'7l 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 andlocking 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 is lifted above the bore 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 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 reser- ,voir 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 theapparatus for filling cans of smaller size than that illustrated by FIG. 1. A cylindrical spacer 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 companys Bulletin DM-l. 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 I 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. I

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 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 whenthe 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 threeway 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 placedon 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. I

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 reasonQthe 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 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.

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.

Dated v March 19, 4

Patent No. 7 3 79 7, 534

Inventofls) Richard H. Skidmore It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1', line 13, change "Aerosol" to aerosol-;

- line 22, change "disclosure" to disclosures. Column 3, line 11, change "into" to -in;

- line 46, change "cans" (1st occurrence) to --cann. Column 6, line 27, change "Arcuate" to --arcuate 7 Column 7, line 1, change "46" to --48+-.

Signed and sealed this 2nd clay of July 1974.v

(S AL) Attest:

EDWARD M. FLETCHER,JR. ,C.MARSH ALL DANN Attesting Officer Commissioner of Patents FORM PQ- 0-69) Y USCOMM-DC seam- 59 U45. GOVERNMENT PRINTING OFFICE I969 O366-33l

Claims

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.