Valveless dispenser for fluent masses

Abstract

A container for toothpaste, cream or other relatively viscous material has a forward continually open outlet or discharge portion, a one-way piston or follower in the container being disposed at the rear of the viscous or fluent material and sealingly engaging the container wall, the one-way follower being moved automatically by ambient air pressure toward the outlet after each dispensing of the material through the outlet, but gripping the container wall to prevent its retrograde movement during dispensing of the material, such dispensing occurring as a result of squeezing or deflecting a forward head portion of the container. The size of the outlet is so proportioned with respect to the viscosity or resistance to change of the fluent mass that retrograde flow of the fluent mass back through the container outlet is restricted upon release of the squeezing or deflecting action on the head, which results in a partial vacuum being created within the container, causing the atmospheric pressure to shift the one-way follower in the forward direction by a distance corresponding to the volume of the fluent material dispensed through the outlet.

Description

The present invention relates to dispensers for fluent materials, and more particularly to a container from which the fluent material is dischargeable, and in which the effective volume of the container decreases in accordance with the volume of the material dispensed.

In U.S. Pat. Nos. 3,088,636 and 2,898,007, dispensers are illustrated in which squeezing of a pliant, elastic head at the forward portion of the container, or squeezing of the container itself at an appropriate region, forces a fluent mass through a discharge outlet, release of the squeezing force effecting automatic closing of an outlet valve and creation of a subatmospheric or partial vacuum in the container, which enables atmospheric pressure to shift a follower or piston, located rearwardly of the mass, in a forward direction within the container to compensate for the volume of material dispensed. The follower piston device is prevented from return movement in U.S. Pat. No. 3,088,636 by a one-way latch secured thereto that grips the wall of the container. In U.S. Pat. No. 2,898,007, the rearward movement of the piston device is resisted by entrapment of air in the container rearwardly of the piston. A rear one-way or check valve permits the atmospheric air to enter the container behind the piston, but such check valve closes to prevent outward flow of the air from the container region behind the piston.

By virtue of the present invention, a discharge valve is not required that closes automatically upon relieving of the deformation force on the container head or other container part, with resultant development of a partial vacuum in the container forwardly of the piston. In the present case, the discharge outlet or nozzle is open continuously. Advantage is taken of the viscosity of the material in the container, its tensile strength, or both, to cause the fluent material or mass to resist withdrawal back into the outlet or nozzle, the atmospheric pressure acting upon the follower or piston to shift it in a forward direction against the mass. The nozzle or outlet size and length are so proportioned with respect to the fluent mass in the container that there is very little tendency for the mass to withdraw into the outlet, such resistance to retrograde flow of the material through the outlet causing the atmospheric pressure to force the piston in the forward direction by an amount substantially corresponding to the volume of the mass dispensed from the container.

The resistance to withdrawal of the mass back through the discharge opening can be increased by providing one or more discontinuities in the path of the mass moving through the discharge outlet, such as steps, change in direction or change in cross-section through the opening. This produces greater resistance to rearward movement of the viscous mass back through the outlet, and greater assurance that the follower piston will move in the forward direction upon release of the deforming force on the head of the container, or other parts of the container, and the return of the head or other container part to its initial shape, which has the effect of producing the subatmospheric pressure within the container in advance of the follower or piston.

In view of the resistance to reverse movement of the viscous mass through the discharge opening, and the follow up of the piston or follower by atmospheric pressure differential imposed therein, it is unnecessary to provide discharge check valves, as in the prior art, such as represented by the above two patents, the discharge outlet remaining continuously in an open state. In fact, it is found that with certain viscous material, and particularly those that exhibit discernible tensible strength, the discharge opening can be made quite large without adversely affecting the operation of the apparatus, and more particularly the forward movement of the follower piston under the influence of atmospheric pressure.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense.

Referring to the drawings:

FIG. 1 is a longitudinal section through a dispensing container embodying the invention;

FIG. 2 is an enlarged fragmentary section through the rear portion of the container disclosed in FIG. 1; and

FIG. 3 is an enlarged cross-section taken along the line 3--3 on FIG. 1.

As illustrated in the drawings, the dispenser includes a container 10 of any suitable material that may have a main body 11 of cylindrical shape, and which is adapted to contain a fluent mass (not shown), such as toothpaste, cosmetic, syrup, molasses, honey, or similar material of relatively high viscosity. The container includes a rear closure or end wall 12 secured thereto by a circumferential rib 13 on the closure fitting within a companion circumferential groove 14 at the rear end of the container body, this rear wall has a vent hole or aperture 15 therethrough to permit entry of the ambient air into the container for action upon a one-way follower or piston device 16 slidably in the container. As described hereinbelow, the follower device is movable in a forward direction, after dispensing of a portion of the fluent mass or material from the container, being caused to shift in the container a distance corresponding to the volume of the fluent material discharged through a forward container outlet passage, nozzle or spout 17, which forms part of a hollow head or dome 18 of pliant, elastic material. The head is suitably secured to the forward end of the container body 11 by a circumferential rib 19 on the head received within the companion circumferential groove 20 of the container.

Although air at atmospheric pressure can shift the follower or piston device 16 in a forward direction, its return or retrograde movement in the container is prevented by a one-way gripper or latch 21 forming part of the follower piston. As disclosed, the piston includes a main body 22 having a central hub 23 and an outer rim 24, with intervening stiffener ribs 25 interconnecting the two parts for relative rigidity. The main body may be made of a suitable material, such as polyethylene, being provided with a forward lip seal 26 extending laterally outwardly of the rim 24, and a rearward lip seal 27 extending laterally outwardly from the rim. These lip seals having sufficient flexibility as to sealingly engage the inner wall 28 of the cylindrical container body 11. Thus, the forward lip seal 26 will be forced by the pressure of the fluent mass in the container against the container wall, to prevent leakage of the mass relatively rearwardly past the piston, whereas a rearward lip seal 27 sealingly engages the inner wall 28 of the container to prevent bypass of atmospheric air forwardly along the follower or piston 16.

Rearward movement of the follower or piston is prevented by the one-way gripper or latch device 21 suitably secured to the follower or piston. As disclosed, the one-way gripper or latch 21 includes a central portion 30 press fitted upon the periphery of the central portion or hub 23 of the follower piston body, this central portion being integral with flexible radial fingers 31 extending therefrom, the fingers deflecting about hinge lines 32 where they join the central portion 30 as the latch device is inserted into the container body 10 through its rear end prior to mounting of the rear closure 12 in the container body. The fingers 31 incline in a transverse and rearward direction, with their outer ends 33 engaging the container wall 28. The arrangement is such that the fingers 31 merely slide along the inner wall of the container when the follower device 16 moves in a forward direction within the container under the influence of atmospheric pressure, but any tendency of the follower device to move rearwardly in the container causes the outer ends 33 of the fingers to grip or latch against the inner wall of the container. In other words, the one-way follower or piston can move forwardly within the container, but it is prevented from moving rearwardly therewithin. The one-way latch device 21 is made of a suitable flexible material, such as steel, phospor bronze, acetal, and the like.

When the dispenser is not in use, a suitable cover 35 may be disposed over the nozzle or spout 17 and over the entire hollow head or dome 18, as illustrated in phantom lines in the drawings. This cover is frictionally retained on the head 18, but is readily removed when the dispenser is to be used.

The nozzle or spout 17 of the hollow head or dome may be used alone, without the L-shaped extension 17a illustrated in the drawings. If the latter is used, it is secured to the nozzle 17 by a circumferential rib 40 on the extension fitting into a circumferential nozzle groove 41.

Assuming a suitable viscous fluent mass is disposed in the container, filling its volume between the piston 16 and the head or dome 18, the cover 35 is removed and the elastomer dome is depressed or deflected inwardly to impose pressure upon the fluent mass, the follower being prevented from moving rearwardly by the engagement of its latch fingers 31 against the inner wall 28 of the container body. The result is a discharge of a portion of the mass through the nozzle 17 in a desired quantity. The deforming force on the head 18 is then released, which automatically reassumes its initial shape, creating a partial vacuum between the head 18 and the follower or piston 16. However, despite the existence of atmospheric pressure at the outer end of the nozzle or spout 17, the resistance of the viscous material to retrograde movement through the nozzle or opening is substantial, so that withdrawal of the material into the spout is negligible. However, air at atmospheric pressure still enters through the vent hole 15 and acts upon the rear portion of the piston, which has a much larger diameter than the passage 17b through the nozzle 17, shifting the piston forwardly within the container by an amount corresponding to the volume of material dispensed through the nozzle. The slight retrograde movement of the viscous fluent mass into the nozzle, as noted above, is insignificant with respect to substantially reducing the partial vacuum in the container, and cannot prevent the atmospheric pressure from moving the piston 16 in a forward direction within the container. However, the slight withdrawal of the mass into the nozzle 17 has the advantage of preventing such mass from remaining externally of the end of the nozzle.

The nozzle passage 17b is of such area and length as to permit outward flow of the viscous mass through the nozzle under the pressure imposed on the mass by deformation of the head 18. However, such area and length are so related to the physical characteristics of the fluent mass that resistance to retrograde flow of the mass is provided upon development of the vacuum condition resulting from reassumption of the head of its normal, initial shape.

In the event that greater resistance to flow of the fluent mass is desirable, the L-shaped extension 17a can be added to the nozzle 17. This causes the fluent mass to drastically change its direction of movement through the extension, introducing resistance to flow of the mass, particularly retrograde flow of the mass through the nozzle structure 17, 17a. Resistance to flow of the mass into and through the nozzle or spout structure 17, 17a, and its retrograde movement, can be further enhanced by changing the shape of the passage 17d through the outer portion of the nozzle, as, for example, by forming it of oval shape, as disclosed in FIG. 3.

It is apparent that the same results are achieved with applicant's dispenser as with the dispensers disclosed in U.S. Pat. Nos. 3,088,636 and 2,898,007, but without the necessity for using one-way discharge check valves. Accordingly, a dispenser has been provided of greater simplicity and economy of production, one which is less subject to malfunctioning.

Claims

I claim:

1. In a dispenser: a container; a viscous fluent mass in said container; said container having a forward continuously open elongate discharge outlet; piston means in said container movable in a forward direction toward the outlet and against the mass in the container; means for restricting movement of said piston means in a rearward direction away from said outlet at all axial positions of said piston means in said container while permitting movement of said piston means in the container in the forward direction; means for reducing the volume of the container forwardly of the piston means to dispense a portion of the mass through said open discharge outlet; means for then increasing the volume of the container forwardly of the piston means to produce a partial vacuum in said container forwardly of said piston means; the cross-sectional area of said outlet and the length of said open outlet being so related to the viscosity of said fluent mass that said partial vacuum is incapable of effecting significant withdrawal of said mass back into said outlet, whereby air at atmospheric pressure moves said piston means forwardly in said container toward said outlet.

2. In a dispenser as defined in claim 1; said restricting means comprising one-way latch means on said piston means engageable with the inner wall of said container to prevent substantially all movement of said piston means rearwardly in said container.

3. In a dispenser as defined in claim 1; said container including a forward pliant, elastic head portion containing said discharge outlet, deformation of said pliant, elastic head portion effecting said reduction in the volume of said container forwardly of the piston means.

4. In a dispenser as defined in claim 1; said restricting means comprising one-way latch means on said piston means engageable with the inner wall of said container to prevent substantially all movement of said piston means rearwardly in said container; said container including a forward pliant, elastic head portion containing said discharge outlet, deformation of said pliant, elastic head portion effecting said reduction in the volume of said container forwardly of the piston means.

5. In a dispenser as defined in claim 1; elongate nozzle means providing said discharge outlet.

6. In a dispenser as defined in claim 1; elongate nozzle means providing said discharge outlet, the outer portion of said nozzle means being disposed at a substantial angle to the inner portion of said nozzle means.

7. In a dispenser as defined in claim 1; said restricting means comprising one-way latch means on said piston means engageable with the inner wall of said container to prevent substantially all movement of said piston means rearwardly in said container; said container including a forward pliant, elastic head portion containing said discharge outlet, deformation of said pliant, elastic head portion effecting said reduction in the volume of said container forwardly of the piston means; elongate nozzle means providing said discharge outlet.

8. In a dispenser as defined in claim 1; said restricting means comprising one-way latch means on said piston means engageable with the inner wall of said container to prevent substantially all movement of said piston means rearwardly in said container; said container including a forward pliant, elastic head portion containing said discharge outlet, deformation of said pliant, elastic head portion effecting said reduction in the volume of said container forwardly of the piston means; elongate nozzle means providing said discharge outlet, the outer portion of said nozzle means being disposed at a substantial angle to the inner portion of said nozzle means.

9. In a dispenser as defined in claim 1; said container having an opening rearwardly of said piston means to allow air at atmospheric pressure to enter said container and act on said piston means.

10. In a dispenser as defined in claim 1; said container having an opening rearwardly of said piston means to allow air at atmospheric pressure to enter said container and act on said piston means; said container including a forward pliant, elastic head portion containing said discharge outlet, deformation of said pliant, elastic head portion effecting said reduction in the volume of said container forwardly of the piston means; elongate nozzle means providing said discharge outlet.

11. In a dispenser as defined in claim 1; said container having an opening rearwardly of said piston means to allow air at atmospheric pressure to enter said container and act on said piston means; said container including a forward pliant, elastic head portion containing said discharge outlet, deformation of said pliant, elastic head portion effecting said reduction in the volume of said container forwardly of the piston means; elongate nozzle means providing said discharge outlet, the outer portion of said nozzle means being disposed at a substantial angle to the inner portion of said nozzle means.