EP0502026A1 - Dispenser with piston assembly for expelling product - Google Patents

Abstract

A non-aerosol dispenser is described. The problem associated with aerosol dispensers is that many of them contain hydrocarbons contributing to air pollution. The non-aerosol dispenser includes an inner cylinder (224) defining a material chamber (211), and having a flow valve (214) at one end. A set of pistons (220) intended to pressurize the contents, carries a cutting edge (288, 289) as well as guides (280, 281). An outer housing (240) receives the guides (280, 281), which advance the piston (220) by rotation of said housing (240) while forcing the cutting edge (288, 289) to pass through the inner cylinder (224). The piston (220) includes an energy amplifier element (252). An ejector (250) and a spring are disposed between the energy amplifier (252) and the valve (214). The spring stores energy from the advance of the piston (220) and transmits it to the ejector (250).

Description

DISPENSER WITH PISTON ASSEMBLY FOR EXPELLING PRODUCT

Background of the Invention

The present invention relates to a dispenser, especially a hand-held spray can in which a piston is advanced to eject a spray upon manual actuation of a valve.

Hand-held spray dispensers are conventional in which a piston is housed within a container below a product to be dispensed. By advancing the piston toward a valved end of the container, the product is forced through the valve.

The present invention constitutes an alternative to aerosol spray dispensers which use pressurized gas as a propellant, the gas being mixed with the product. Gases currently in use contain hydrocarbons which have increasingly come under attack as a serious contributor to air pollution. For example, hydrocarbons released in the atmosphere can react with nitrogen oxide and sunlight to form smog.

There have heretofore been proposed gasless spray dispensers which propel the product by mechanically generated propelling forces. For example, pump type dispensers have been proposed which require a mechanical displacement of a pump stem each time that a user dispenses a spray. Such dispensers are incapable of storing energy and thus eject the contents in the form of intermittent spray bursts rather than a prolonged spray. Other dispensers have been proposed which rely upon mechanical actuation, as exemplified by U.S. Patents No. 3,815,787; No. 3,195,168; No. 2,728,097; and No. 2,738,905. In U.S. Patent 3,815,787, a dispenser is disclosed wherein a piston is mounted within a helical groove formed on an inside surface of a cylindrical container. By rotating the container relative to a top discharge portion of the dispenser, the piston is caused to ascend within the container to discharge product located thereabove. However, since the helical groove faces the contents chamber, it is necessary to confine the liquid within a bag, or else the liquid would escape along the helical groove. The need for bags may increase the manufacturing costs and presents the risk that the bag can become ruptured as the result of being pinched between the piston and either the helical groove or vertical guide slots which receive radial tabs of the piston. In Patent No. 3,195,168, such an axially threaded rod is provided which extends axially within the container and carries a threaded follower. Disposed above the follower is a piston which seals against the inside surface of the contents chamber. The rod is rotated by means of a knob mounted at the bottom of the container. A spring between the follower and piston transmits motion from the follower to the piston to store energy. By rotating the rod, the follower and piston are raised to dispense the contents. To prevent the follower from rotating, the follower and the wall of the contents chamber are formed with complementary non-circular cross-sections. Such a non-circular cross-section reduces the inner volume of the container and thus reduces the amount of liquid product which can be held. Also, the need for a separate actuator rod and turning knob may increase the cost and complicate the assembly of the apparatus. While the spring effectively stores energy, it does not transmit the energy to the piston as uniformly across the area of the piston as would be desired, thereby resulting in a less-than-optimum spray pattern.

U.S. Patent No. 1,762,943 discloses a dispenser for viscous material, such as toothpaste. The dispenser includes a piston shell disposed within a cylinder. An outer shell is connected to the.piston shell for common rotation and longitudinal movement therewith. It is necessary to cut off the bottom of the cylinder as the inner and outer shells travel toward the discharge valve. Such an operation is inconvenient and creates cuttings that must be disposed of.

In Patents No. 2,728,097 and No. 2,738,905 dispensers are disclosed which involve the need for a threaded rod and which present the problem of leakage of product past a dispensing piston.

It would be desirable to provide a relatively low-cost, easily assembled, non-aerosol dispenser which does not require that the product be stored in a bag and which, if a bag is used, minimizes the risk of the bag being ruptured. It would also be desirable to provide such a dispenser which makes it possible to store propulsion energy so that a continuous discharge can be effected with a highly uniform spray pattern. Summary of the Invention

The present invention involves a non-aerosol dispenser which comprises an inner cylindrical wall- defining a contents chamber. A discharge valve is disposed at one longitudinal end of the chamber. A piston is disposed within the chamber in longitudinally spaced relationship from the discharge valve. The piston includes a cutting edge directed toward the cylindrical wall. An outer cylindrical wall is disposed around the inner wall. The outer wall is rotatable relative to the inner wall and cooperates with the piston, whereby rotation of the outer wall causes the piston to approach the discharge valve while forcing the cutting edge to cut through the inner wall, characterized in that the outer wall cooperates with the piston such that the piston travels longitudinally relative to the outer wall as the piston approaches the discharge valve.

The inner wall includes a helical groove which receives guide members of the piston. The piston is prevented from rotating, by means of longitudinal grooves formed in the inner wall.

The piston comprises an ejector member and an energizer member spaced below it to define a space between the ejector and energizer members. The space is filled with compressible gas, such as air, which acts like a spring to store energy. The compressible gas may be confined in the space by means of seals on the ejector and energizer members, or the gas may be contained in an enclosure, such as a flexible bellows, which extends between the ejector and energizer members.

The contents to be dispensed may be located directly in the contents chamber, or contained within a flexible bag located within the contents chamber. Brief Description of the Drawing The objects and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof in connection with the accompanying drawings in which like numerals designate like elements, and in which: FIGURE 1 is a longitudinal sectional view taken through a dispenser according to the present invention;

FIGURE 2 is a perspective exploded view of the dispenser depicted in FIG. 1;

FIGURE 3 is a longitudinal sectional view taken through an energizer member of a piston assembly according to the invention;

FIGURE 4 is a bottom plan view of the energizer member depicted in -FIG. 3;

FIGURE 5 is a fragmentary side view of the energizer member;

FIGURE 6 is a fragmentary longitudinal sectional view of the dispenser depicted in FIG. 1; FIGURE 7 is a view similar to FIG. 1 of a modified piston assembly according to the invention; and

FIGURE 8 is a view similar to FIG. 6 of the piston assembly depicted in FIG. 7.

Detailed Description of Preferred Embodiments o.f the Invention

A dispenser (200) according to the present invention includes a first housing body (212) having a cylindrical wall (224) and an upper end wall (226) . Formed in an outer surface (228) of the cylindrical wall (224) are a pair of longitudinal grooves (230) which extend partially through the cylindrical wall . from the outside to leave knock-out wall portions (232) (see FIG. 15) . An inside surface (234) of the cylindrical wall remains smooth and continuous.

An annular flange (236) projects radially outwardly from a lower end of the outer surface (228) . A cylindrical wall (240) of a second housing body (218) rests on the flange (236.) . That cylindrical wall (240) receives the cylindrical wall (224) in telescoping fashion, whereby the cylindrical walls (224, 240) constitute inner and outer cylindrical walls, respectively. The cylindrical wall (224) includes longitudinally extending, circumferentially spaced slots (241) at its lower end to enable the outer wall (240) to be inserted over.the inner wall (224). The outer wall (240) includes inner and outer surfaces (242, 244) . A disk (245) inserted into the inner surface (244) of the cylindrical wall (224) closes the bottom of the first housing body (212) . That disk (245) can be suitably bonded to the cylindrical wall (224) . The inner surface (242) includes a helical groove (243) which faces radially inwardly. That groove (243) serves to guide a piston assembly (220) , as will be explained. The helical groove (243) is situated radially outwardly of the longitudinal grooves (230) , whereby the helical groove (243) constitutes an outer groove and the longitudinal grooves (230) constitute inner grooves.

An upper end of the outer wall (240) is received within an annular channel defined between the inner wall (224) and an outer cylindrical skirt (247) which is joined to the inner wall (224) by an outwardly extending portion (248) of the end wall (226) .

The piston assembly (220) comprises an ejector member 250, and an energizer member (252) located below the ejector member (250) . The ejector member (250) includes a downwardly extending annular skirt portion (258) which carries an 0-ring (251) .

The energizer member (252) includes a seal carrier comprising a disk portion (266) and an annular skirt (268) extending upwardly therefrom. Disposed within the skirt (268) is an elastic sealing member (264) which bears sealingly against the inner surface (234) of the inner wall (224) . The seal carrier (266, 268) is preferably formed of a stiff plastic material, whereas the elastic sealing member (264) is preferably formed of rubber or a suitably resilient plastic. Alternatively, the seal carrier and the sealing member could be integrally molded of a suitably elastic material.

Formed between the sealing member (264) and the ejector member (250) is a sealed space (265) capable of retaining pressurized air. Pressurization of that space (265) can be achieved by the insertion of a needle through the sealing member (264) after the components of the dispenser have been assembled. Holes (267 and 269) formed in the disks (245) and (266) , respectively, accommodate the insertion of the needle. Pressurized air would be introduced through the needle and into the space (266) to pressurize the space to a suitable pressure,, e.g., 40 psi. When the needle is pulled back out of the sealing member, the latter is self-sealing to seal the puncture made by the needle. As will be subsequently explained, the air in the space (265) functions as an air spring to store and transmit the energy.

Projecting radially outwardly from the disk (266) are guide members (280, 281) which are received within the helical groove (243) . Carried by the disk (266) are a pair of cutting elements (288, 289) having cutting edges (291) facing longitudinally forwardly toward lower edges of the knock-out wall portions (232) of the inner wall (224) . The cutting elements (288, 289) , which could be formed of metal or a suitably hard plastic, are initially positioned to lie within diametrically opposed ones of the slots (241) . As a result, rotation of the energizer member (252) relative to the inner wall (224) is prevented.

It will be appreciated that the rotation of the outer wall (240) relative to the inner wall (224) in a selected direction produces forward longitudinal movement of the energizer member (252) toward a valve (214) mounted in the upper end wall (226) , due to the presence of the guide members (280, 281) within the helical groove (243) . As a result, the cutting elements are forced to cut through the knock-out wall portions (232) . Simultaneously, an upper force is transmitted from the energizer member (252) to the ejector member (250) through the pressurized air disposed within the space (265) . The ejector member (250) thus pressurizes the product located thereabove. When the pressure of the product exceeds the pressure of air in the space (265) , further forward movement of the energizer member (252) causes the air to be compressed, thereby storing energy. The air constitutes a gas spring which transmits forces to the ejector member (250) more uniformly than the spring 54 of the earlier described embodiment and thus achieves a more uniform spray through the valve (214) .

The pressurized air within the space (265) also forces the skirt (258) of the ejector member radially outwardly against the surface (234) to aid in the sealing action. Such sealing action may be sufficient to enable the 0-ring (251) to be omitted. The upper end wall (226) and the ejector member (250) are of similar inverted cup-shape, to ensure that all of the contents of the container have been dispensed when the energizer member (250) finally engages the end wall (226) .

In operation, the user rotates the outer wall (240) to raise the piston assembly and pressurize the contents of the chamber (211) as well as the air in space (265) . The energizer member (252) travels longitudinally without rotation as the piston assembly rises. It may be possible to eliminate the longitudinal grooves (230) (i.e., it may be unnecessary to form knock-out wall portions in the inner wall (244)) due to the ability of the energizer member (252) to travel longitudinally without such grooves. The longitudinal movement of the piston assembly (220) is induced by the helical groove (243) which acts on the guides (280, 281) . That longitudinal movement of the piston assembly is made possible by the cutting action of the cutting elements (288, 289) . The contents will be expelled under their own pressure as well as under the pressure of stored air energy within the space (265) , whereafter the piston assembly will be further raised to repressurize the contents and the air space (265) . The portion of the surface (234) which engages the contents can be made smooth and continuous , i.e., free of grooves, whereby leakage of the contents and/or rupturing of a bag which contains the contents can be prevented. It will be appreciated that the piston assembly could be raised and lowered by any suitable manually actuable mechanism.

It would be possible to make the seal carrier (266) longer than shown, in order to provide an additional pair of guide members (280, 281) located below he shown pair. That would serve to stabilize the seal carrier.

It would be possible to reverse the positions of the helical and longitudinal grooves, i.e., by locating the helical groove (243) on the inner cylinder (224) , and locating the longitudinal grooves (230) on the outer cylinder (240) . The piston would include guide members slidably disposed in those grooves. In such a case, the energizing member (252) would be rotated along with the outer cylinder and would cut through a helical knock-out portion of the inner cylinder formed by the helical groove. A single cutting edge (288) would be provided which would be oriented to face in the direction of rotation. As the piston is rotated, it would travel longitudinally relative to the outer cylinder, as permitted by the longitudinal grooves. A modified embodiment of the piston assembly is depicted in FIGS. 7 and 8. That modified piston assembly (220A) prevents the air situated between the ejector member (250A) and the energizer member (252A) from escaping past the energizer and/or ejector members or migrating through the housing wall(s) of the dispenser, as might occur over a period of time in connection with certain plastic materials from which the housing walls could be formed. Such migration of air would eventually destroy the air spring properties of the piston assembly.

In accordance with the present invention, however, the air is retained between the ejector member (250A) and the energizer member (252A) by means of a flexible enclosure (300) . The enclosure is preferably in the form of a bellows formed of a suitable plastic or rubber material which is connected in an air-tight manner at its upper nd to a cylindrical projection (302) of the ejector member (250A) and at its lower end to a cylindrical projection (304) of the energizer member (252A) .

The energizer member (252A) is of a more - simplified structure as compared with that of the earlier disclosed embodiment, because the confining of air within the bellows (300) makes it unnecessary for the energizer member to form a seal with the surface (234) of the cylindrical wall (224) . The energizer member (252A) includes a passage (306) for enabling an inner chamber (308) defined by the bellows to be filled with air by means of a syringe, for example. The syringe could be inserted through a self-sealing rubber plug (310) disposed at the lower end of the passage. The ejector member (250A) includes a sealing portion (312) which forms a seal against the surface (234) as the piston is raised to pressurize the contents of the dispenser. Since the compressible air of the piston assembly is contained within the bellows (300) , the air will not contact the wall of the dispenser and thus will not be able to migrate therethrough or escape past the energizer and/or ejector members. Hence, the piston assembly (220A) is useful with all dispensers, regardless of the materials from which the cylinder wall is formed.

In operation, as the outer valve (240) is rotated to raise the energizer member (252A) , the air within the bellows (300) is compressed, and the bellows itself collapses. As the product is dispensed, the ejector member (250A) rises, thereby relieving the air pressure within the bellows chamber (308) and causing the bellows to re-expand.

Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A dispenser comprising inner cylindrical wall means (224) defining a contents chamber (211) , discharge valve means (214) disposed at one longitudinal end of said chamber, piston means (220) disposed in said chamber in longitudinally spaced relationship from said discharge valve means, said piston means carrying cutting edge means (288, 289) directed toward said inner wall means, an outer cylindrical wall means (240) disposed around said inner wall means, said outer wall means being rotatable relative to said inner wall means and cooperating with said piston means whereby rotation of said outer wall means causes said piston means to approach said discharge valve means while forcing said cutting edge means to cut through said inner wall means, characterized in that said outer wall means cooperates with said piston means such that said piston means travels longitudinally relative to said outer wall means as said piston means approaches said discharge valve means.

2. A dispenser according to claim 1, characterized in that said outer wall means includes a groove (243) having longitudinally spaced ends, one of said longitudinally spaced ends being situated closer to said discharge valve than the other of said longitudinally spaced ends, said piston means carrying guide means (280, 281) received in said groove for sliding movement therein as said piston means approaches said discharge valve means.

3. A dispenser according to claim 2, characterized in that said groove is helical.

4. A dispenser according to claim 3, characterized in that said inner wall means includes an outer surface (228) , a pair of longitudinally extending grooves (230) extending partially radially through said outer surface to form knock-out wall portions (232) of said inner wall means, said cutting edge means facing longitudinally toward said knock-out wall portions.

5. A dispenser according to claim 2, characterized in that said inner wall means includes longitudinally extending, circumferentially spaced slots (241) formed completely radially therethrough in an end thereof opposite said discharge valve means, said cutting edge means initially disposed in respective ones of said slots.

6. A dispenser according to claim 5, characterized in that said outer cylindrical wall means includes a radially outwardly projecting flange (236) at an end thereof disposed opposite said discharge valve means, said inner cylindrical wall means being seated on said flange.

7. A dispenser according to claim 1, characterized in that said piston means comprises an energizer member (252) to which said cutting edge means is connected, an ejector member (250) disposed between said energizer member and said discharge valve means, and spring means disposed therebetween for storing . energy and for transmitting such energy to said ejector member.

8. A dispenser according to claim 7, characterized in that said spring means comprises a compressible gas contained in a space (265) between said ejector and energizer members.

9. A dispenser according to claim 8, characterized in that said ejector member includes an annular skirt (258) arranged to be pressed radially outwardly against said inner cylindrical wall means by said compressed air in said space.

10. A dispenser according to claim 8, characterized in that said energizer member includes a sealing element (264) facing said ejector member and creating a fluid seal with an inner surface of said inner cylindrical wall means.

11. A dispenser according to claim 8, characterized in that said energizer member includes a disk (266) which carries an elastic seal extending across the cross-section of said cylindrical wall means, said disk having a hole (269) therethrough to accommodate the insertion of a needle through said seal for pressurizing said space.

12. A dispenser according to claim 8 including a flexible enclosure extending between said ejector and energizer members and defining a chamber containing said compressible gas.

13. A dispenser according to claim 12, characterized in that said enclosure comprises' a bellows.

14. A dispenser according to claim 12, characterized in that said compressible gas is air.

15. A dispenser according to claim 1, characterized in that said contents are contained in a flexible gag -situated in said contents chamber.

16. A dispenser according to claim 1, characterized in that said outer wall means is fixed against longitudinal movement relative to said inner wall means during rotation of said outer wall means.

17. A dispenser according to claim 1, characterized in that said outer wall means includes a pair of longitudinally extending grooves, said inner wall means including a helical groove extending partially therethrough to form a helical knock-out in said inner wall means, said piston means including guides slidably disposed in said grooves, whereby said piston is rotated by said outer wall means, said cutting edge means facing in the direction of piston rotation to cut through said helical knock-out.