JPH0217650Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an applicator for products, and in particular,
having a driven piston slidably disposed within the applicator, the piston exhibiting minimal predetermined frictional resistance to axial movement within the applicator, and being forced downwardly by an axial force; It concerns an applicator designed to be easily moved upwards.

[Conventional technology and problems]

Much effort has been devoted to dispensing devices for liquids and other fluids. For example, Swedish patent no. A shaped flexible hollow head is attached having a groove opening therethrough. In one version of the container according to the above-mentioned patent, the transparent tube is provided with a plunger, which is provided with a number of ring-shaped flanges extending rearwardly from it relative to the hollow head. In use, a portion of the hollow head is manually crushed, thus reducing the volume within the head and ejecting material from the groove. When the crushing force is released, the groove closes as the hollow head returns to its original volume, thus creating a slight negative pressure within the container and thus moving the plunger in the direction of the hollow head. .

U.S. Patent No. 3,088,636 (inventor Walter B.
Spatz, May 7, 1963) describes a container for a semi-solid or fluid body having dispensing means for controlling the discharge of said body; The vessel has a flexible plastic head, a self-closing evacuation opening, and a one-way (one-way movement) follower means that can reduce the effective volume within the vessel. The inward deflection of the plastic head reduces the volume within the dispenser and opens the outlet, thus allowing fluid to exit therefrom. Attached to the central rear portion of the follower is a one-way latch mechanism having a number of circumferentially spaced latch fingers extending outwardly and rearwardly; It engages the inner wall of the container and thus prevents rearward movement of the follower within the container. When the pressure on the head is released, the lip of the discharge outlet is closed and the head elastically returns to its original shape, thus creating a partial vacuum in the container and forcing it all the way over the driven means. Atmospheric pressure is allowed to act, thus forcing the follower means forward within the container.

U.S. Patent No. 3,768,705 (inventor Walter B.
Spatz, October 30, 1973) also relates to a dispensing device for fluids, which is movably slidable in a flexible plastic container behind the fluid contained therein. A single-path follower is shown.
A butterfly check valve is placed at the outlet of the container, which opens in response to the container being pushed at any point to permit dispensing. When the force pushing on the container is removed, the outlet check valve closes, thus preventing air from entering the container as the flexible container wall returns to its original position, thus preventing air from entering the container. Negative pressure is generated. The follower has one-way latching means similar to that shown in the aforementioned U.S. Pat. has. As in the aforementioned US Pat. No. 3,088,636, the follower is moved forward in the container by atmospheric pressure as a result of the vacuum being created after the dispensing operation.

U.S. Patent No. 4301948 (Inventor Joachim Czech
and Hans Sieghart, November 24, 1981) describes a pump action dispenser for liquid and pasty products, the dispenser having a container with a lower end. is closed by a slidable piston and has a head at its upper end, said head having a variable volume pump chamber. The pump chamber itself is isolated from the product in the container by the first check valve.
The first check valve can be opened only towards the pump chamber, which is further isolated from the outlet passage by a second check valve, which can be opened only towards the outlet. Due to the pressure manually applied to the pump head piston from the outside, the volume of the pump chamber is reduced and the product is forced through the second check valve and the outlet, thus dispensing a portion of the product. When said pressure is removed, the pump chamber returns to its original volume, thus creating a partial vacuum in the pump chamber, the second check valve is closed, and the first check valve is opened, so that the product is From the container it is allowed to enter the pump chamber and the dispensed amount of product is changed.

As shown in the above-mentioned patents, despite many efforts made in this field, problems such as complexity of the applicator, assembly of parts, unreliability of function, excessive cost, etc. The problem still remains. Prior art applicators require complex valve structures or multi-piece follower means, thus requiring tedious assembly operations, and yet are not always reliable in operation. These shortcomings have led to messy, inconvenient, and expensive applicators.

[Purpose of invention]

The purpose of the present invention is to eliminate the above-mentioned problems.

It is an object of the present invention to provide an economical and reliable applicator that requires minimal parts and assembly operations.

Another object of the invention is to have an elevator-type piston for dispensing a product containing solids.
It is an object of the present invention to provide a hand-operated applicator (i.e., a adhesive or cream applicator).

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved applicator having a driven piston of integral construction, said piston which enhances the functionality and convenience of the applicator relative to other parts of the applicator. It can be designed to be optimal.

Still another object of the present invention is to provide a pump-type dispenser that is more convenient than conventional dispensers without increasing the cost.

[Summary of the idea and effects]

In the dispenser according to the present invention, the product is placed in the axially extending lumen of the tubular container body;
The body has an upper end onto which the product is applied and an open lower end. A driven piston is slidably disposed within the lower end of the tubular container body, the piston comprising:
Keep the product on it. The driven piston has a flat surface that contacts the product in the container body and a downwardly projecting side wall, the side wall having at least one peripheral contact band having the same cross-sectional shape as the lumen. Made in one piece. Said side wall is capable of elastically expanding and contracting longitudinally in response to an axial force exerted on said planar portion, such change in length causing an inversely proportional change in the lateral side of the contact band. Occurs during the directional dimension. The driven piston is hollow, the inner surfaces of the plane and side walls are exposed to atmospheric pressure, and the contact band is dimensioned for an interference fit within the lumen of the container body so that the piston remains stationary. At some point a predetermined normal force is applied to the side wall of the lumen.

[Example of idea]

The present invention will be explained below with reference to embodiments shown in the drawings.

1-3 show details of the pump-type dispenser 10, which includes a container body 50, a self-sealing dispensing nozzle 30, a resilient upper end 20, and a driven piston 70. The product to be dispensed (not shown) fills the dispenser 10 and can be any fluid or liquid.

The container body 50 is made of a substantially rigid material (e.g., metal, cardboard, plastic, or a composite material of two or more of these) and has a tubular portion 51 open at both ends. A snap engagement groove 54 is formed on the outer side 52 of the upper end. Tubular part 51
preferably has a circular axially extending lumen, the internal cross-section of said lumen may be of any desired shape (e.g., square, rectangular or oval), but preferably circular. . This is because it is difficult to seal around pistons that have different shapes.

Although absolute rigidity of the tubular portion 51 is not required,
Substantial rigidity is desired. This is because the amount of product dispensed during a dispensing operation is influenced by the volume changes allowed by the non-rigid structure, and in addition, due to the rigidity, the driven piston 70
This is because it helps to have the inner wall of the tubular section parallel to the piston to provide a proper seal between the piston and the piston. Preferred materials for the tubular section 51 are plastics, for example polypropylene, polyacrylonitrile or polyethylene terephthalate. This is because plastic is easy to manufacture.

An integral base 6 is provided on the outer periphery of the lower end of the container body 50.
0 is made, the base 60 extends downwardly and outwardly from the outer surface of the tubular section 51, and the tip of the base 60 is in the same plane as the lower end of the tubular section 51 and spaced outwardly therefrom.

The resilient upper end 20 is preferably made of a resilient material (eg, polypropylene, polyethylene terephthalate, polyacrylonitrile, elastomer or polymer) and has a rounded ceiling 21 with a smooth outer surface. The rounded ceiling section 21 is approximately 41.3 mm (1.625 inches)
When used for a container body having an outer diameter of
Preferably made to have a thickness within the range of approximately 0.43 to 0.51 mm (0.017 to 0.020 inches) with a radius of curvature of approximately 50 mm (2.0 inches), but the actual thickness will depend on the material used. , can vary widely depending on factors such as the diameter of the container. A skirt 22 extends downward from the outer periphery of the ceiling portion 21, and a snap engaging rib 25 is formed on the inner periphery of the lower end of the skirt 22. The skirt 22 and its snap engaging ribs 25 are
The upper end 20 is sized to permit locking engagement with the upper end 52 of the tubular section and its snap engagement groove 54. As will be appreciated, the seal along the connection between the top end 20 and the container body 50 must be liquid-tight at the application pressure for proper operation of the applicator. The illustrated snap/lock connection is provided by way of example only;
Such a seal may be obviated by making the container body 50 and the top end 20 integral or by connecting them by screws, spin welding, adhesives, or the like.

A dispensing passage 23 is created through the skirt 22 and extends radially outwardly through the tubular projection 28 . surrounding the protrusion 28;
An outwardly projecting circular retaining wall 26 is formed at a radial distance from the outer surface of the retaining wall 26 .
are placed concentrically around a common central axis perpendicular to the central axis of the main body 50. Protrusion 28 and retaining wall 26 are connected to outlet base ring 24 at their inner ends. A retaining rib 27 is formed on the inner periphery of the tip of the retaining wall 26, and the retaining rib 27 is attached to the protrusion 2.
Go inward towards the outer surface of 8.

The self-seal dispensing nozzle 30 may consist of any check valve that allows product to be extruded under pressure and provides a clean product shut-off and seal when the pressure is released. The check valve in the illustrated example is made of silicone rubber (e.g., "Silastic® MDX 4" available from Dow Corning, Midland, Mich.).
4526"), although a variety of other materials and molding methods may be used. Although the nozzle 30 shown in FIG. Other types of nozzles having a construction of
Inside the nozzle 30, a cylindrical open inlet end 32 and an outlet end are formed, said outlet end being connected to each pleat 31.
terminating in a closed groove 33 between. The nozzle 30 is approximately 0.76 mm at its cylindrical open end 32.
(0.03 inch) wall thickness and at pleat 31
It is desirable to have a wall thickness of 0.51 mm (0.02 inch). At the bottom end of the open end 32 is a mounting flange 3.
4 are made in one piece, and the mounting flange 34 projects outward in a plane perpendicular to the central axis of the nozzle 30. The nozzles 30 are preferably molded with the corrugations 31 closed at their tips, after which the grooves 33 are cut as desired, thereby ensuring that said grooves 33 can be completely closed. Ru. Thus, being able to close completely is important. This is because the nozzle 30 must be able to prevent fluid (air, etc.) from flowing into the applicator.

Nozzle 30 is attached to applicator 10 by fitting its open end 32 over projection 28 and is positively held in position by retaining ring 40 .
The ring 40 slides over the outer surface of the nozzle 30 and is snapped past a retaining rib 27 extending inwardly of the retaining wall 26. Retaining ring 40 is preferably made from polypropylene or polyethylene, but may be made from other relatively rigid materials. Dimensions of retaining ring 40 and said rib 27
is positioned such that when the nozzle 30 is installed, the ring 40 is pressed against the flange 34 to ensure that the flange 34 is tightly sealed against the outlet base ring 24. The manner in which the nozzle 30 is attached to the applicator is not critical and can be done in various known or conceivable ways, for example by gluing, spin welding or even by mechanical means. Alternatively, the nozzle 30 can be placed inside, close to the dispensing passageway (e.g., in an outwardly extending outlet groove).
There may be cases where it is desirable to install.

The integral follower piston 70 is preferably made of polypropylene or polyethylene, but may be made of other resilient materials, and is slidably mounted within the container body 51 of the dispenser 10, as shown in FIG. put in motion. In the illustrated example, the piston 70
has a convex surface 76, on the lower periphery of which is integrally attached a downwardly projecting side wall, said side wall having thin bellows-like depressions or folds 73. The convex surface 76 is about 38 mm when used in a container body 50 having an inner diameter of about 41.3 mm (1.625 inches).
(1.5 inches), but this curvature can be varied. Each recess (or corrugation) 73 consists of one upwardly facing frustoconical wall 74 and one downwardly facing frustoconically shaped wall 75, said walls being separated at their joining line 72. hinged. Each corrugation 73 is interconnected at their upper and lower ends by an integral contact band 78 , the uppermost corrugation 73 being connected to the outer periphery of the piston face 76 along another peripheral contact band 78 . As shown in FIG. 3, the piston 70 is hollow, and the piston surface 76 and the inner surfaces of the side walls and corrugations 73 are exposed to the outside air since the bottom of the piston 70 is open.

Here, the term "bellow-like" refers to an integral thin-walled corrugated structure, an accordion-like structure, as part of the continuous sidewall of the piston; forming a pleated periphery that allows the piston sidewall to expand and contract longitudinally in response to axial pressure applied to the piston face; such change in length creates a The lateral dimension of the at least one peripheral contact band produced is inversely varied. For example, the resilient corrugations 73 of the piston 70 allow the piston 70 to be compressed longitudinally in response to downward pressure applied on the piston surface 76; in the unconstrained condition, this compression causes An inversely proportional expansion of the outer diameter of contact band 78 occurs. The piston 70 is hollow and its open bottom prevents the longitudinal expansion and contraction of the piston side walls and the interference of air that would otherwise be trapped within the piston (i.e., the interference of axial forces acting on the piston surface 76). Forgive without receiving.

FIG. 4 shows a cross-sectional view of a bellows-shaped piston with only one peripheral contact band. This piston 170 has a substantially rigid piston surface 17
6. Side wall 183 protruding downward, friction ring 181,
and has a peripheral contact band 178 made in the side wall between surface 176 and friction ring 181. The convex shape of the sidewalls creates resilient pleats that allow the sidewalls 183 to expand and contract longitudinally in an unconstrained condition, and such changes in length cause the lateral dimensions of the contact band to change. changed inversely proportionally. Friction ring 181 provides a predetermined amount of frictional resistance to movement of piston 170 within the applicator lumen, allowing an axial force to be exerted on piston face 176, thereby causing piston sidewall 183 is longitudinally expanded and contracted (as described below). Any means for generating a predetermined normal force (ie, frictional resistance to the movement of the piston) against the inner surface of the tubular portion 51 may be used in place of the friction ring 181. This peripheral contact band of the piston does not need to be a separate structure from the sidewall itself. That is, contact band 1
78 may be formed by the largest radial dimension of sidewall 183. In some cases, it may be desirable to form the contact band 178 as an outwardly extending rib-like structure (not shown), thus increasing the sealing ability between it and the inner surface of the applicator lumen. obtain.

Referring again to FIGS. 1 to 3, the piston 7
0 peripheral contact band 78 is made conformal to the internal cross-sectional shape of tubular section 51 and dimensioned to provide an interference fit within tubular section 51 and thus has a profile perpendicular to the inner surface of the lumen. A force is exerted, thus creating a predetermined amount of frictional resistance to both upward and downward movement of the piston 70 within the container body 50. Actual lateral expansion of contact band 78 is prevented by the substantially plush inner surface of tubular portion 51, so that axial compressive forces (such as those caused by pressure applied to the upper surface of piston face 76) ) is transmitted to the bellows folds 73, thus increasing the normal force with which the contact band 78 presses against the inner surface of the tubular part 51, thus increasing the frictional resistance to the downward movement of the piston 70 within the container body 50. will be increased. On the other hand, the piston 70
The axial tensile force (force generated by the pressure acting on the underside of the piston face 76) applied to causes an inversely proportional decrease in the outer diameter of the contact band 78, thus
The normal force generated by the contact band 78 on the inner surface of the tubular part 51 is reduced, and therefore the frictional resistance to the upward movement of the piston 70 is reduced.

The bellows corrugations 73 of the piston 70 shown in FIGS. 2, 3, 7, and 8 have a serrated or squared shape, although other shapes may be used. For example, bellows pleats 73 may be shaped with rounded joints 72 and/or rounded contact bands 78, such shapes being
Rounded contact band 17 of piston 170 shown
This is shown as 8.

The function of piston 170 in FIG. 4 is similar to that described for piston 70 above. The friction ring 181 and contact band 178 of the piston 170 are made to have the same cross-sectional shape as the internal lumen of the applicator and are sized to provide an interference fit within the tubular portion 51 and thus A normal force is generated against the inner surface of the profile 51 and thus a predetermined amount of frictional resistance to the upward and downward movement of the piston 170 (i.e.
8). Piston surface 17
The outer periphery 180 of 6 is also dimensioned to provide a seal and a predetermined amount of frictional resistance to axial movement of the piston within tubular section 51 . The axial compressive force applied on the upper surface of the piston surface 176 is transmitted to the bellows-like folds (indentations) 173 made in the side wall 138, but the friction ring 181 resists downward movement due to friction. The transmitted force tends to collapse the thin sidewall 183 outwardly, thus increasing the radial dimension of the contact band 178. Since the tubular section 51 actually prevents its radial dimension from expanding, such a dimensional change does not actually occur, and in fact the contact band 17 against the inner surface of the tubular section 51
8 is increased, thus piston 170
The frictional resistance to the downward movement of is increased. In contrast, the axial stretching force applied to the piston 170 tends to stretch the side wall 183 in the longitudinal direction,
Thus, the radial dimension of contact band 178 is reduced, and thus the normal force is reduced, and thus:
Frictional resistance to upward movement of piston 170 is reduced.

The overall length of the driven piston of FIG. 3 is determined, at least in part, by the size and number of each corrugation 73. FIG. 3 shows the included angle 77 and pitch H of each pleat 73, and the included angle 77 has a downward angle α and an upward angle β. angle 77
is preferably within the range of approximately 30° to 120°,
The angles α and β are approximately equal. Pitch H is the distance measured between the centers of two successive contact bands 78, as shown in FIG. As will be described later, the frictional resistance against the movement of the driven piston 70 can be changed as required by changing some or all of the included angles 77 of each pleat 73, and the pitch H can also be changed as required.
Adjustments can be made to change the overall length of piston 70 as desired, but depending on the method of molding piston 70, it can be adjusted to change the overall length of piston 70 while still maintaining good structural shape of the corrugations.
There may also be limits to which the pitch H can be varied (for sidewalls having the required thickness).

As shown, piston 70 has four complete corrugations (indentations) 73, each corrugation 73 having an included angle of approximately 60 degrees, and angles α and β both approximately 30 degrees. If by extrusion blow molding, a pitch of at least about 3.2 mm (0.125 inch) is applied to each pleat.
It has been discovered that it is desirable for good molding of 3. Although smaller pitches H can be formed, pitches smaller than about 4.5 mm tend to negatively impact the lateral variation potential of the corrugations 73 and, therefore, the performance of the piston. Preferably, the pitch H is equal to at least 10% of the outer diameter of the piston 70. Moreover, the piston 70 is
It has been discovered that it must be of sufficient length to avoid misalignment within the container during its useful life. Sufficient length will, of course, vary with the diameter of the applicator. For example, if the inner diameter of the tubular portion 51 is approximately 41.3 mm (1.625 inches), the piston contact length L is measured between the uppermost band 78 and the lowermost band 78, as shown in FIG. It has been discovered that it is desirable for the vine length to be at least 12.7 mm (0.5 inch) to prevent the above-mentioned axial misalignment. has an included angle 77 of 60°;
A piston with angles α and β of 30° and a pitch of 4.5 mm (0.175 inch) is 12.7 mm
Approximately three bellows 73 are required to obtain the (0.5 inch) length. Similarly, the piston 170 shown in FIG. 4 must be of sufficient length to resist misalignment within the container. The total length L′ of the piston 170 is mainly due to the length of the convex side wall 1
83, the length L' is preferably at least 12.7 mm (0.5 inch) when used within a tubular lumen 51 having an inner diameter of about 41.3 mm (1.625 inch).

The pistons 70, 170 may be made of a wide variety of resilient materials having a strength that allows them to remain substantially stable under successive loading and unloading conditions over extended periods of time, such as
700 to 28,000 Kg/cm ² (10,000 to 400,000 psi). Thermoplastic materials are preferred because they are inexpensive and easy to mold.

To create a predetermined amount of frictional resistance to upward and downward movement of the piston 70 within the container body 50, the outer diameter of the contact band 78 of the piston 70 is
Approximately 0.25 mm (0.010 inch) from the inner diameter of the tubular portion 51
It is desirable to make it large. This deliberately oversized dimension provides an interference fit in the piston 70 which generates a force having a force component acting perpendicularly to the bore of the tubular portion 51 along the contact band 78; A predetermined frictional resistance to movement is thus created. The predetermined minimum frictional resistance to movement of the piston 70 may also be varied by other factors in addition to the degree of interference described above. For example, the material of the piston, the softness (hardness) of the material, the wall thickness, etc. also affect the frictional resistance to movement. The number of contact bands 78 is also a factor, since each contact band 78 increases the frictional resistance of the piston 70. The appropriate number of contact bands can vary widely based on the frictional resistance required for proper dispensing operation of the applicator (i.e., the piston can resist downward forces without substantial downward movement). (and must be able to move forward (upward) under atmospheric pressure after the dispensing operation, and must be able to seal the dispenser). Any applicator must have at least one contact band 78, but multiple (e.g., three) contact bands 78 may be used to create sufficient friction in the applicator and to provide an adequate seal. It is desirable to have contact bands 78 (or four).

Friction ring 181, contact band 178 and outer circumference 18 of piston surface 176 within tubular section 51
An interference engagement of zero similarly creates a predetermined amount of frictional resistance to axial movement of the piston 170 within the container body 50. In a preferred embodiment, the outer diameter of friction ring 181 and contact band 178 is
Approximately 0.38 mm (0.015 inch) from the inner diameter of the tubular portion 51
The diameter of the outer periphery 180 of the piston face 176 is made larger by about 0.13 mm (0.015 inch).

FIG. 5 shows yet another embodiment of the piston of the present invention. In this piston 270, the side walls of the piston expand and contract longitudinally in response to axial forces applied on the piston surface, and such changes in length cause the opposite lateral dimensions of the peripheral contact band. No bellows pleats are required to create a proportional change. The piston 270 has at least one integral periphery that is of the same cross-sectional shape as the lumen and that can exhibit changes in longitudinal and lateral dimensions as described above in response to the applied axial direction on the piston surface. It can be any structure with contact bands.

This driven piston 270 is the piston 7 described above.
0, a relatively thin but rigid flat surface 27 that can be made of any resilient material.
6. Side wall 283 protruding downward and friction ring 2
It has 81. Said side wall 283 consists of interlocking helical threads 278 which emerge from below the periphery of the piston face 276 and are mounted on the periphery of the friction ring 281 at the lower end. The piston 270 has two right-handed and two left-handed helical threads 278;
78 makes one complete turn from piston face 276 to friction ring 281. The helical strips 278 are arranged in a cross-section and are interconnected at intersections 285, thus forming a web-like or porous continuous structure that constitutes the sidewall 283. The helical ridge 278 also acts as a peripheral contact band that is conformal to the cross-sectional shape of the applicator lumen and, in the resting state, is used to generate a predetermined force perpendicular to the inner surface of the lumen. Preferably, it is dimensioned to provide an interference fit within the cavity. Friction ring 281 also provides a predetermined amount of frictional resistance to movement of piston 270 within the applicator lumen, such that axial forces acting on piston surface 276 cause piston sidewall 283 to It is dimensioned to allow for longitudinal expansion and contraction. The piston surface 276 is similarly sized to create a predetermined normal force against the inner surface of the applicator lumen and form a seal therewith to keep the product above the piston surface. It will be done.

The frictional resistance to movement created by friction ring 281 allows the axial force acting on piston face 276 to longitudinally expand and retract sidewall 283 . Each helical thread 278 tends to expand laterally when compressed longitudinally and inversely contracts laterally when stretched longitudinally. An opposed pair of helical strips 278 (i.e.
The intersection of the left-handed and right-handed pairs) is the "twist" of each strip (in the unrestrained state,
By preventing the "twisting" that the strips would do to escape such longitudinal stresses, a change in lateral dimension is ensured in response to the longitudinal stresses. Although it has been discovered that at least two oppositely placed helical strips 278 are desirable to prevent such twisting, any number of helical strips 278 may be used.
It has been discovered that 78 may also be used satisfactorily and that their intersecting shape, spacing, etc. may be varied as desired.

One method of making the sidewalls is to provide a cylindrical tubular sidewall with a number of shapes (e.g., to form the spiral/diamond shape shown in FIG. 5) that give the desired functional properties. This is a method of drilling holes.

The dispenser 10 is first partially assembled with the exception of the driven piston, and then the partially assembled dispenser 10 is turned upside down and inserted from the open end of the container body 50 into said open end. The product is filled leaving sufficient unfilled space for the piston 70 (or piston 170 or other piston made in accordance with the present invention), after which the piston can be inserted into the container body 50. desirable. After insertion of the piston 70, a bottom cover (not shown) may be placed over the open end of the container body for aesthetic purposes;
Such a cover must not prevent atmospheric pressure from being maintained within the hollow lower part of the piston. This is because if this is prevented, the operation of the applicator 10 will be hindered. The method of filling applicator 10 is not critical, and any suitable method may be used.

During the dispensing operation, the rounded portion 21 of the resilient upper end 20 is pressed down by hand, thus reducing the volume within the dispensing device and thus increasing the pressure of the product within it. . Although pressure changes within the applicator are exerted through the product placed therein onto the piston face 76 and then to the side walls of the piston, the piston 70 has some resistance to backward movement within the applicator. This force tends to "substantially" compress the pleats 73 beneath it, since the tape is designed to have a minimum frictional resistance. Here, "substantially" refers to portions 70 of piston 70.
is supposed to actually compress or expand when loaded or unloaded in an unrestrained state, but only shows extremely slight compression or expansion when restrained by the container body 50. It means that.
Therefore, the substantial expansion or contraction is actually the transmission of loads and forces by the structure of the piston 70.

The sidewall of the piston has structural elements (i.e., corrugations 73 or helical striations 278) that are not parallel to the longitudinal axis of the piston, and these elements extend longitudinally in response to an axial force applied thereon. such deflection tends to inversely change the lateral dimension of the sidewall. It has been discovered that the substantial axial compression of the pleats 73 tends to substantially expand the lateral dimension of the sidewall of the piston 70 at the contact band 78. Piston surface 7
6 is convex and thus tends to increase the effective lateral dimension of the piston by attempting to expand its effective diameter in response to increased product pressure. However, it is desirable that the piston surface 76 be substantially rigid. This is because the extent to which it changes during loading reduces the amount of product applied. One way to ensure substantial stiffness of the piston face 76 is to increase its thickness. In the preferred embodiment, the wall thickness of piston face 76 is approximately 1.65 mm (0.065 inch), while the wall thickness of sidewall and bellows 73 is approximately 0.64 mm.
(0.025 inch). The corresponding wall thicknesses are the surface 176 of the piston 170 and the side wall 183 of the piston 170.
It can also be used satisfactorily.

The tendency of the piston 70 to expand its lateral dimension in response to the increase in pressure within the applicator 10 causes the vertical movement of the piston against the inner surface of the tubular portion 51 along its contact band 78. The force is greatly increased and the resistance of piston 70 to backward movement within applicator 10 is increased proportionately. Due to this increased resistance to movement,
The pressure within the applicator is allowed to increase as the resilient upper end 20 is pushed down further. This internal pressure increases until it exceeds the critical pressure required to begin dispensing from the nozzle 30. In the illustrated example, such a critical pressure allows the liquid product contained within the container to pass through a relatively small passageway 23 (which in the preferred embodiment is approximately 6.4 mm, i.e.
having a diameter of 0.25 inch), the pressure required to open the pleats 31 of the nozzle 30, and the pressure required to force the product through the opened pleats 31. The dispensing pressure for the applicator can therefore be scheduled and controlled by varying the dimensions of the dispensing channel and the functionality of the nozzle, taking into account the viscosity of the product to be dispensed. In the illustrated example, the viscosity of the liquid product is approximately 0.11 Kg/cm ² (1.5 psig) when the viscosity is 300,000 cp (Bruckfield).

When the pressure within the applicator 10 reaches a critical dispensing pressure in the dispensing passage 23, product is dispensed, and such dispensing continues until the pressure within the applicator falls below said critical pressure. . When the force pushing down on the upper end 20 is released, the pressure within the applicator is reduced to the resilient upper end 2.
As 0 returns to its original position, it begins to fall. When the internal pressure approaches atmospheric pressure, the nozzle 30 tends to close elastically. As the resilient upper end 20 continues to move towards its original position, a partial vacuum is created within the applicator 10, and such negative pressure causes atmospheric pressure to act on the outer surface of the leaves 31 of the nozzle 30, The groove 33 is thus closed, and the nozzle is therefore closed in a liquid-tight manner. The partial vacuum within the applicator 10 does not escape from the nozzle 30 or the seal formed between the contact band 78 and the inner surface of the tubular section 51. This is because these can prevent outside air from entering the applicator 10. In the preferred embodiment, 0.25 mm between the piston 70 and the inner diameter of the tubular section 51.
(0.010 inch) interference fit ensures adequate sealing with five contact bands 78. Other methods for liquid-tightly sealing piston 70 within container body 50 may be used equally satisfactorily.

The imbalance of pressures acting on the piston surface 76 (i.e. vacuum acting on the top surface and atmospheric pressure acting on the bottom surface) causes an effective upward force to be exerted on said surface, thus stretching successive pleats 73 upwardly. (ie, the pitch H is increased), thus reducing the effective diameter of each individual corrugation 73 and piston 70. This tendency reduces the normal force generated by the pleats 73 against the inner surface of the tubular section 51 at the contact band 78, so that the resistance to the movement of the piston within the applicator is proportional. is reduced to facilitate its upward movement. The piston 70 is moved upwards by a distance corresponding to the amount of liquid product applied, and thus the resilient upper end 2
It serves to relieve (weaken) the partial vacuum created by the recovery of reach. The dispenser 10 is now ready for the next dispense operation.

Actuation of applicator 10 is accomplished by piston 170 or 2.
70 is substantially similar to that described with respect to the piston 70 above, with the piston surface 176
(or 276) is transmitted so that the axial pressure acting on contact band 178 (or helical strip 27
8), the frictional resistance generated by the friction ring 181 of the piston 170 (or similar ring 281 of the piston 270) is substantially reduced throughout operation of the applicator. remains constant.

6 and 7 show another preferred embodiment of the dispenser 100 according to the invention, which includes a container body 15 for containing the liquid product to be dispensed.
0, a resilient dispensing top 120, a self-sealing dispensing nozzle 30, a driven piston 70' and a cap 65. Similar to the dispenser 10 described above, this dispenser 100 also includes pistons 70, 17.
0 or 270 may be satisfactorily used in place of piston 70'. As shown, container body 150 is substantially similar to container body 50 described above. Tubular part 151, its upper end 152, snap engagement groove 1
54, and the base 160 are part 5 of the first embodiment.
1, 52, 54, and 60, respectively. A retaining wall 155 protrudes inward from above the inner surface of the tubular portion 151, and the retaining wall 155 partially closes the uppermost end of the container body 150. A large number of integrally formed piston stop bodies 161 are provided at intervals on the inner periphery of the lower end of the container body 150, and the piston stop bodies 16
1 consists of a rectangular protrusion that protrudes inward a relatively short distance toward the central axis of the container body 150. The stop 161 is shown only as an example of a means for keeping the piston 70' within the container body 150 during shipping and initial use; The following means may also be used. The cap 65 is cup-shaped and has a substantially flat circular ceiling 67, a side wall 68 extending downwardly therefrom, and a snap-engaging groove 66 formed in the inner periphery of the lower end of the side wall 68.

The elasticity imparting upper end portion 120 has a one-piece structure;
Rigid button ceiling 121, downwardly projecting cylindrical button wall 191, rounded base 191
a, concentric septum 192, substantially rigid shoulder 19;
3 and a rigid skirt 122. Application top 120 is preferably shoulder molded from a resilient material (e.g., polypropylene, polyethylene terephthalate, polyacrylonitrile, elastomer or polymer composite) and is
0.38~0.51mm (0.015~0.020 inch) in 92
, with the remainder having a slightly thicker thickness. The thickened area remains substantially rigid throughout the dispensing operation, and the thin septum 192 is deformed, thus changing the volume of the dispenser 100. As shown in FIG. 7, a snap engaging rib 125 is provided on the inner periphery of the lower end of the skirt 122.
is formed, and the ribs 125 snap into liquid-tight engagement with the upper end 152 and snap engagement groove 154 of the container body 150. This snap engagement means and means corresponding to what has been said for the first embodiment above are shown by way of example only; other coupling means may be used instead, and the application upper It is also possible to make the part 120 and the container body 150 integrally, thereby eliminating the need for a connecting means.

Application channel 12 through cylindrical button wall 191
3 is made, and the passage 123 is surrounded by a retaining wall 1
26, and a retaining rib 127 extending inwardly from the inner surface of the retaining wall 126. Such a structure is shown as one example of a structure for attaching dispensing nozzle 30 to applicator 100, and other attachment structures may be used or contemplated. This structure is shown as one example of a structure for attaching the applicator nozzle 30 to the applicator 100, and it is contemplated that other attachment structures may be used. The self-sealing nozzle 30 includes:
The nozzle 30 is the same as described for the previous embodiment.

Piston 70' is essentially the same as piston 70 previously described, but the face of piston 70' has been modified so that it can fit into the inner surface of the upper end of the dispenser. The circular disk portion 91 of the piston is
It has a frusto-conical upper surface 92 extending upwardly from the piston face 76' and is attached to the disk portion 91 at its outer periphery. A protrusion 93 projects upward from the center of the upper surface 92, and the protrusion 93 has a flat ceiling surface 94. The disk portion 91 is attached to the retaining wall 155
Piston 7
0' is allowed to move upwardly within the container body 150 until the piston face 76' reaches the lower surface of the retaining wall 155. The protrusion 93 moves telescopingly upwardly within the dispensing top end 120 to ensure that the majority of the content product is dispensed. Modifying the piston surface in this manner is one way to minimize the amount of product remaining in the dispenser.

Snap engagement ribs 129a extend outwardly from the periphery of skirt 122, and stop flange 129b also extends outwardly from the tip (lower end) of skirt 122, which provide a means for attaching cap 65 to applicator 100. This is shown as an example. The snap engagement groove 66 of the cap 65 is
5 is placed over the dispensing top end 120 and placed in the closed position, lockingly engages the rib 129a.

The operation of dispenser 100 is similar to that described for dispenser 10 above, but differs in the manner in which the volume of the dispenser is varied. The resilient top end 20 of the applicator 10 and the resilient top end 120 of the applicator 100 are shown only as examples of means for varying the volume of the applicator according to the present invention; Many other structures for effecting such volume changes may also be used or contemplated. Such volume change means may be designed to optimize the force and stroke (distance traveled) required to impart a predetermined amount of volume change within each applicator. for example,
Such means require a relatively large amount of axial movement (stroke length) over a relatively small area to provide the desired volume change, but a relatively small amount to generate the required applied pressure. It may be designed to require only axial force, which may facilitate use of the applicator by children. Volume varying means can therefore be a valuable tool for optimizing the functional characteristics of the dispenser in terms of familiarity and convenience of use.

This dispenser 100 is also desirably partially assembled except for the piston 70' (or 70, 170, 270, etc.) for product filling from the bottom as described for the dispenser 10 described above. After filling from the bottom, the piston 70' moves into the container body 150.
In this case, the lowermost contact band 7
8 (or friction ring 181 if piston 170 is used) is snapped past piston stop 161. When actuated, a downward force is applied by hand onto the button ceiling 121,
Therefore, the button ceiling part 121 and the button wall 19
1 is pushed down, so that the diaphragm 192
It is bent inward as shown by the broken line in the figure. Such axial movement of the resilient upper end 120 reduces the volume within the applicator 100 and increases the pressure within the applicator. As described for the first embodiment, the driven piston 70' resists rearward movement in response to such pressure increase, so that product is dispensed from the dispensing passage 123 when the internal pressure reaches the required pressure. . In some designs of volume change means, such as the resilient top end 120, irreversible deformation of the means can occur if excessive downward force is applied on the top end. For example, if an excessive downward force is applied on the button ceiling part 121 of this embodiment,
Excessive distortion or breakage can occur at the rounded base 191a of the wall 191 or near the peripheral shoulder 193, thus rendering the entire applicator inoperable. One way to prevent such failure is to provide a means in the applicator to actively limit axial movement of the volume change means. An example of such positive limiting means is shown in FIG. 7 and is a retaining wall 155. By placing such limiting means in place, they can also serve to quantify the amount of product dispensed in each single dispensing operation.

The piston may be designed to exhibit different resistance to axial movement upwardly and downwardly. In the embodiment described above, the piston 70 has an articulated construction with pleats (or bellows) 73 such that the resistance of the piston 70 increases against downward movement in response to increased pressure within the applicator. It decreases for upward movement in response to vacuum (or negative pressure) within the applicator. That is, the piston 70 can move upward more easily than downward. The degree of difference in ease of movement of such pistons can be adjusted in several ways. For example, it can be adjusted by changing the included angle 77 and the angles α and β. A preferred range for included angle 77 is 30° to 120°, but theoretically it could be 0° to 180°. However, the large angle
Each pleat exhibits only a slight lateral expansion upon axial compression and therefore exhibits little frictional resistance to movement. If the angles α and β are close to 0° (for example 15°), each pleat will exhibit very little lateral expansion due to the force of crushing the bellows, but will exert a large normal force against the inner wall of the container, causing a large This creates a piston that exhibits low variability in lateral dimensions but high frictional resistance to movement under load. Increasing the angle makes it easier to change the lateral dimension (i.e. more tolerant of interference between the piston and the inner surface of the container, despite differences in container inner diameter), but with less difference in frictional resistance to movement (i.e. , a piston is created in which, for a constant load applied to the piston, there is a small increase in the normal force exerted on the inner wall of the container). However, as the included angle 77 is increased above 120 degrees, both the tolerance and the frictional drag differential begin to decrease. The included angle of each pleat is thus adjusted to create a driven piston with the desired degree of interference within the container, optimum latitude, and optimum frictional resistance against the applicator. A piston with greater tolerance may be advantageous in compensating for manufacturing tolerances in container and piston dimensions common in constrained mass manufacturing. Therefore, sacrificing frictional drag differential for greater piston tolerance may be compensated in some cases. Although angles α and β are approximately equal in the illustrated example, this need not be the case. It has been discovered that to obtain a large resistance difference under load, only one of the angles α or β need be small (for example 15°), while the other can be large. Such a combination has a small pitch and a small angle α,
It may be useful to facilitate molding of pistons with β. This is because the molding operation is simplified.

In the illustrated example, the piston surface 76 is convex, with a desired radius of curvature of approximately 38 mm (1.50 inches), and is located near the uppermost corrugation 73. Meeting special application requirements can be accomplished by varying the shape and position of the piston surface 76. For example, with a flat piston face in the center of the piston and both ends of the piston left open,
Can be mounted horizontally. Such a piston is
Shows no difference in ease of movement within the applicator.
Slightly easier upward movement is achieved by placing the flat piston face closer to the upper end of the piston. If the piston surface 76
If it is concave upwards, as opposed to convex, then
Instead of the uppermost folds (bellows) having an increased tendency to expand radially in response to downward pressure, they tend to expand radially in response to upward pressure, and thus have an increased tendency to expand radially in response to downward pressure. The frictional resistance is slightly increased and the uppermost contact band 78
The seal will be enhanced. Such a concave shape would be desirable to ensure a tight seal for air-sensitive content products. Similarly, the piston faces of other pistons according to the present invention may have various shapes and thicknesses to accommodate desired functional characteristics. For example, upwardly convex surface 176 of piston 170
It is desirable to have a large thickness, so that
The surface 176 can readily expand radially in response to downward axial pressure, thus allowing the outer periphery 18
0 and the inner surface of the tubular section 51 is strengthened. The piston surface can be made convex, concave, or a combination of flat and convex or concave shapes to precisely control its performance characteristics. Also,
Substantially all of the content product has been administered and thus:
In order to reduce the amount of product remaining in the vessel, a specially shaped piston surface may be used that allows the piston to fit into the shape of the top of the dispenser (e.g., piston 70' in Figure 7). .

In addition, in order to achieve the desired predetermined value of the frictional resistance of the piston within the container, the variable capacity of the volume changing means, the shape of the piston surface, the required applied pressure, and the viscosity and lubricity of the liquid product to be applied are also important. must be taken into account. Viscosity has a substantial effect on the pressure effects in the dispensing passageway and determines the number and type of sealing means required for effective operation of the piston and for retaining the product within the dispenser. It can be a key (important factor). For example, an upwardly concave piston surface 76 may be desirable to ensure a fluid-tight seal for air-sensitive liquid products having a relatively low viscosity, whereas for a relatively high viscosity liquid product, it may be desirable to An upwardly convex piston surface may be sufficient. It has been discovered that high viscosity fluids increase the reliability of piston seals. Since the lubricity of the liquid content and the resistivity coefficient of the material of the driven piston and container body directly affect the friction value within the dispenser, these influences must be taken into account in the design of each dispenser. must be included.

The piston described above may be used as a follower in any product applicator in which the product is contained in an axially extending bore in which the piston can be slidably placed. For example, the piston 70 is
As shown in cross-section in FIG. 8, it may be used in a solid product applicator 1000 in which the piston 70 is slidably positioned within the lower end of the lumen of the applicator 1000. It is then manually pushed upwards within the lumen to dispense the product, keeping the solid product P above it. Although applicator 1000 is shown as cylindrical, the interior and exterior surfaces may be of various shapes. Dispenser 1000 also has a snap-on cap 1065, but cap 1065 is shown only as an example of a lid for a dispenser. This applicator is particularly advantageous for use with solid products such as sticky deodorants that are rubbed onto the axillary surface. This is because the piston 70 resists being moved rearwardly within the lumen in response to the axial compressive force generated by the rubbing during the dispensing operation.

The embodiments of the present invention will be summarized as follows.

1. In a dispenser for a product, the product is placed in an axially extending lumen of the tubular container body;
The container body has an upper end at which the product is applied and an open lower end, a driven piston is slidably disposed within the lower end, the piston retaining the product thereon, the piston comprising: made of a resilient material and having a surface in contact with the product and a peripherally attached side wall, the inner surfaces of the surface and the side wall being exposed to atmospheric pressure, and the side wall having at least one thin wall. bellows-like pleats are created, each of the uppermost and lowermost said pleats being connected to an integral peripheral contact band of the same shape as the cross-sectional shape of said lumen, said contact band interfering within said lumen. an applicator dimensioned to mate and configured to generate a predetermined normal force against the inner surface of the lumen in a static state;

2 A number of thin-walled bellows-like pleats are made in said side wall, said pleats being connected together one after another by peripheral contact bands at their upper and lower ends, thus forming a thin-walled accordion-shaped structure. wherein said sidewall is allowed to be substantially strained by an axial force, said substantial longitudinal strain causing an inversely proportional strain in a radial dimension of said peripheral contact band to be elastic. The applicator according to the above aspect, wherein the applicator is configured such that the applicator is configured to allow the application to occur.

3. The applicator according to aspect 1 or 2, wherein the side of the surface portion that contacts the product is a convex surface.

4. The applicator according to aspect 1 or 2, wherein the side of the surface portion that contacts the product is a concave surface.

5. The applicator according to aspect 1 or 2, wherein the side of the surface portion that contacts the product is flat.

6. An applicator according to any one of the above embodiments 3 to 5, wherein the outer periphery of the face is connected to the upper end of the uppermost bellows fold by an uppermost integral peripheral contact band.

7. The applicator of embodiment 2, wherein the bellows-like pleats have an included angle of about 30° to 120°.

8 The above bellows-like folds are at least approximately 3.2 mm.
(0.125 inch) pitch
Dispense device as described in section.

9. A pump-type dispenser for liquid products, wherein the product is placed in an axially extending lumen of a tubular container body, said container body having an upper end communicating with a discharge passage and an open lower end; A driven piston is slidably disposed within the lower end, the piston sealing the body against escape of the product from the lower end, the piston being made of a resilient material and contacting the product. a face and a peripherally attached side wall, the side wall having at least one integral peripheral contact band having a cross-sectional shape of the lumen, the side wall extending over the face; substantially elastically longitudinally expandable and retractable in response to an axial force applied thereto, such change in length resulting in a substantial inversely proportional change in the lateral dimension of said peripheral contact band; The piston is hollow, the inner surface of the face and the side wall are exposed to atmospheric pressure, and the contact band is
dimensioned to provide an interference fit within the lumen, thereby creating a predetermined normal force against the inner surface of the lumen in a static state, and increasing the normal force when pump pressure is applied to the product. hand,
Movement of the piston toward the open end of the lumen is prevented, and when the pressure within the product drops below atmospheric pressure, the vertical force is reduced so that external pressure causes the piston to move toward the upper end of the lumen. , an applicator configured to be allowed to move until equilibrium is achieved.

10. The applicator according to embodiment 9 above, wherein the side wall further comprises at least one thin-walled bellows-like pleat.

11 further comprising a friction ring that provides a predetermined frictional resistance to movement of the piston within the lumen in a static state, the bellows-like folds comprising:
comprising an outwardly convex, continuous, and downwardly projecting side wall, the side wall being attached to the face at its upper periphery and to the friction ring at its lower periphery, the side wall being attached to the friction ring at its lower periphery; Applicator according to embodiment 9 above, having a peripheral contact band formed therebetween.

12 further comprising a friction ring dimensioned for an interference fit within the lumen, the friction ring comprising:
exerting a predetermined normal force on the inner surface of the lumen in a static state, the side wall further having at least two opposite helical ridges extending downwardly from below the periphery of the face; The lower end of the friction ring is mounted on the periphery of the friction ring, and the striations are of the same cross-sectional shape as the lumen, thus forming at least two peripheral contact bands. dispenser.

13. A pump dispenser for liquid products, wherein the product is placed in an axially extending lumen of a tubular container body, the container body having an upper end communicating with a discharge passageway and an open lower end; A driven piston is slidably disposed within the lumen, the piston sealing the body to prevent product from escaping from the lower end, the piston being made of a resilient material and contacting the product. and a peripherally attached side wall, the piston being hollow, the inner surfaces of the face and side wall being exposed to atmospheric pressure, and the side wall having at least one thin-walled bellows corrugation. the upper and lower ends of the pleats are each connected to an integral peripheral contact band of the same shape as the cross-sectional shape of the lumen, the contact band being configured in an interference fit manner within the lumen; This creates a predetermined normal force against the inner surface of the lumen in a static state, and when pump pressure is applied to the product, the normal force is increased and the piston is directed towards the open end of the lumen. movement is prevented, and when the pressure within the product falls below atmospheric pressure, the normal force is reduced and external pressure is allowed to move the piston toward the top of the lumen until equilibrium is achieved. A dispenser configured as follows.

14 A number of thin-walled bellows-like pleats are made in the side wall, said pleats being interconnected together at their upper and lower ends by peripheral contact bands, thus forming a thin-walled accordion-shaped structure. , whereby said sidewall is allowed to be substantially longitudinally distorted by said pump pressure, said substantial longitudinal distortion causing an inversely proportional substantial lateral dimension of said peripheral contact band. The resulting strain and resulting lateral expansion of the contact band increases the normal force exerted by the contact band against the inner surface of the lumen, and the substantial lateral contraction of the contact band increases the 14. Applicator according to embodiment 13 above, configured such that normal forces are reduced.

15. The applicator according to aspect 14, wherein the side of the surface portion that contacts the product is a convex surface.

16. The applicator according to aspect 14, wherein the side of the surface portion that contacts the product is a concave surface.

17. The applicator according to aspect 14, wherein the side of the surface portion that contacts the product is flat.

18. An applicator according to embodiment 15, wherein the outer periphery of the face is connected to the upper end of the uppermost bellows fold by an uppermost integral peripheral contact band.

19. The applicator of embodiment 14, wherein the bellows-like pleats have an included angle of about 30° to 120°.

20 Each of the above bellows-like folds is at least about 3.2
Applicator according to embodiment 19 above, having a pitch of mm (0.125 inches).

[Brief explanation of the drawing]

1 is a partially exploded perspective view of a preferred embodiment of the applicator having a driven body according to the present invention; FIG. 2 is a vertical sectional view taken along line 2-2 of FIG. 1; and FIG. FIG. 4 is a vertical sectional view of another embodiment of the driven piston according to the present invention; FIG.
6 is a partially exploded perspective view of a second preferred embodiment of a dispenser having a driven body according to the present invention; FIG. FIG. 6 is an enlarged vertical cross-sectional view of the second preferred embodiment taken along line 7--7 in FIG. 6, and FIG. 8 is a vertical cross-sectional view of a third embodiment of the applicator having a follower according to the present invention. 10... Applicator, 20... Elastic upper end, 30
. . . Application nozzle, 50 . . . Container body, 70 . . . Driven piston, 73 .

Claims (1)

[Claims for Utility Model Registration] 1. In a dispenser for a product, the product is put into a lumen extending in the axial direction of a tubular container body,
The container body has an upper end at which the product is applied and an open lower end, a driven piston is slidably disposed within the lower end, the piston retaining the product thereon, the piston comprising: made of a resilient material and having a product-contacting surface and a peripherally attached side wall, said side wall having at least one integral peripheral contact band having the same cross-sectional shape as said lumen; , said sidewall is capable of substantially elastic longitudinal expansion and contraction in response to an axial force exerted on said face, such change in length causing a lateral dimension of said peripheral contact band to change. An inversely proportional substantial change occurs, the inner surfaces of the face and sidewalls are exposed to atmospheric pressure, and the contact band is dimensioned to be an interference fit within the lumen, thereby providing a static condition. an applicator configured to generate a predetermined normal force against an inner surface of the lumen at the lumen; 2. The applicator of claim 1, wherein the side wall further comprises at least one thin-walled bellows-like pleat. 3. further comprising a friction ring for creating a predetermined frictional resistance to movement of the piston within the lumen in a static state, the bellows-like folds comprising:
a generally convex, continuous, downwardly projecting side wall, said side wall being attached to said face part at its upper periphery and having a peripheral contact band created between said face part and said friction ring; A dispensing device according to claim 2 of the patent registration claim. 4. The applicator of claim 3, wherein the contact band is located at the greatest radial dimension of the side wall.