Patent Description:
Caulks, adhesives and sealants are commonly delivered by a dispensing gun from a cartridge. The dispensing guns often include a plunger on a piston rod to push the material out of the cartridge. Due to space between the outer edge of the plunger head and the inner wall of the cartridge, material may bypass conventional plunger heads and may lead to contamination of the piston rod. If the piston rod is contaminated, the dispensing gun may stop working properly.

<CIT> discloses an example of a known caulking gun with a radially expending pressure disk.

The present invention also provides a sealant cartridge assembly comprising: a sealant-containing cartridge including a front cartridge opening and a rear cartridge opening; a plunger slidably mounted inside the sealant-containing cartridge including a front plunger end structured and arranged to contact and apply force against the sealant contained in the cartridge, a rear plunger opening, and a plunger sidewall extending between the front plunger end and rear plunger opening; and a radially expandable plunger head assembly of claim <NUM>, mounted on a plunger rod and at least partially inserted through the rear plunger opening structured and arranged to apply outward radial force against the plunger sidewall when the plunger rod is advanced forward inside the sealant-containing cartridge and the plunger-head assembly presses against the plunger to apply the force against the sealant; wherein the radially expandable collet of the radially expandable plunger head assembly is structured and arranged to apply the outward radial force against the plunger sidewall.

The present invention further provides a radially expandable plunger head assembly for use in a sealant cartridge assembly including a sealant-containing cartridge and a plunger slidably mounted inside the sealant-containing cartridge. The plunger head assembly comprises: a ram head slidingly mounted on a front end of a plunger rod having a front face structured and arranged to contact a front plunger end, and a rear collet engagement surface; and a radially expandable collet mounted on the front end of the plunger rod having at least one radially expandable finger structured and arranged to contact the collet engagement surface of the ram head and move radially outward toward a sidewall of the plunger when the plunger rod is advanced forward inside the sealant-containing cartridge, wherein the plunger comprises a front wiper ring, and at least one radially expandable finger of the collet contacts the plunger at an axial location adjacent to the front wiper ring, and wherein the at least one radially expandable finger of the collet comprises a ram-engaging inner surface and an outer contact ring segment.

<FIG> illustrate features of a sealant dispensing cartridge assembly <NUM> of the present invention. The cartridge assembly <NUM> includes a cartridge holder <NUM> having an open front end <NUM> and a standard threaded rear end <NUM>. As shown in <FIG>, a sealant cartridge <NUM> is removably inserted inside the cartridge holder <NUM>. The sealant cartridge <NUM> has a cylindrical inner wall <NUM>, a rounded front shoulder <NUM>, and a front neck <NUM>. A front cartridge opening <NUM> is provided in the front neck <NUM> and has standard internal threads <NUM>. The front neck <NUM> of the sealant cartridge <NUM> extends through the open front end <NUM> of the cartridge holder <NUM>. The sealant cartridge <NUM> includes a collared rear cartridge opening <NUM>. The interior volume of the sealant cartridge <NUM> defines a sealant chamber that may be filled with various known types of sealants. As used herein, the term "sealants" includes known types of sealants as well as adhesives and caulks.

As shown most clearly in <FIG>, <FIG> and <FIG>, a plunger <NUM> is slidably inserted in the sealant cartridge <NUM> in contact with the cylindrical inner wall <NUM>. The plunger <NUM> includes a front plunger end <NUM> and plunger sidewall <NUM>. The sidewall <NUM> has an inner surface <NUM> and an outer surface <NUM>. The plunger sidewall <NUM> includes a front wiper ring <NUM> and a rear wiper ring <NUM>. A rear plunger opening <NUM> is provided in the plunger <NUM>.

As shown in <FIG> and <FIG>, the sealant dispensing cartridge assembly <NUM> includes a radially expandable plunger assembly <NUM>. The plunger assembly <NUM> includes a ram head <NUM> having a front face <NUM>, rear face <NUM> and conical collet engagement surface <NUM>. A circular front opening <NUM> is provided in the front face <NUM> of the ram head <NUM>, and a smaller rear opening <NUM> is provided through the rear face <NUM> of the ram head <NUM>. A ram bolt <NUM> is inserted through the front opening <NUM> of the ram head <NUM>. The ram bolt <NUM> has a front bolt head <NUM> and a threaded rear end <NUM>. The diameter of the front bolt head <NUM> is smaller than the diameter of the front opening <NUM>, but larger than the diameter of the rear opening <NUM>.

As shown in <FIG> and <FIG>, a plunger rod <NUM> extends into the sealant cartridge <NUM>. The plunger rod <NUM> includes an internally threaded front end <NUM> and a standard rear end <NUM> that extends rearwardly outward from the sealant cartridge <NUM> and cartridge holder <NUM>.

As shown most clearly in <FIG>, <FIG> and <FIG>, a radially expandable collet <NUM> is mounted on the ram bolt <NUM>. The collet <NUM> includes a rear base surface <NUM> with radially expandable fingers <NUM> extending forwardly therefrom. Each radially expandable finger <NUM> has a ram engaging inner surface <NUM> and a radially outermost contact ring segment <NUM>. A central hole <NUM> extends through the rear base surface <NUM> of the collet <NUM>. As shown most clearly in <FIG> and <FIG>, the ram bolt <NUM> is threaded on the plunger rod <NUM> through engagement of the threaded rear end <NUM> of the bolt and the internally threaded front end <NUM> of the plunger rod. Any other suitable type of mounting arrangement between the ram bolt <NUM> and plunger rod <NUM> may be used, such as pins, mechanical fasteners, press fits, adhesives and the like. A washer <NUM> surrounds the ram bolt <NUM> and contacts the front end <NUM> of the plunger rod <NUM>. The ram bolt <NUM>, plunger rod <NUM> and washer <NUM> are secured together for axial movement within the sealant cartridge <NUM>.

<FIG> illustrate the radially expandable plunger head assembly <NUM> in a retracted position, while <FIG> illustrate the plunger head assembly <NUM> in a radially expanded position. As shown in <FIG>, the ram head <NUM> is rearwardly spaced from the front end <NUM> of the plunger <NUM>. In this position, the radially expandable collet <NUM> is in its retracted position in which the bolt head <NUM> is fully inserted in the front opening <NUM> of the ram head <NUM>. As shown most clearly in <FIG>, the ram engaging surface <NUM> of each radially expandable finger <NUM> of the collet <NUM> does not contact the conical collet engagement surface <NUM> of the ram head <NUM> in the retracted position.

As shown in <FIG> and <FIG>, when the plunger rod <NUM> is pushed into the sealant cartridge <NUM> against the force of a sealant contained in the sealant chamber <NUM>, the washer <NUM> attached to the front end <NUM> of the plunger rod <NUM> presses against the rear base surface <NUM> of the collet <NUM>, which causes the ram engaging inner surfaces <NUM> of the radially expandable fingers <NUM> to contact the rear conical collet engagement surface <NUM> of the ram head <NUM>. As shown in <FIG> and <FIG>, opposing force provided by the sealant in the chamber <NUM> against the front end <NUM> of the plunger <NUM> resists the forward movement of the plunger <NUM> while the ram head <NUM> continues to move inside the plunger <NUM> until its front end <NUM> contacts the inner surface of the plunger <NUM>. Continued movement of the plunger rod <NUM> causes the ram bolt <NUM> to travel forward toward the front opening <NUM> of the ram head <NUM>. During such forward movement of the ram bolt <NUM>, the washer <NUM> pushes against the rear base surface <NUM> of the collet <NUM>, causing the ram engaging inner surface <NUM> of each finger <NUM> to contact the conical collet engagement surface <NUM> of the ram head <NUM>, thereby forcing the fingers <NUM> radially outward. The contact ring segment <NUM> of each finger <NUM> is forced radially outward to thereby contact the inner surface <NUM> of the sidewall <NUM> of the plunger <NUM>.

As shown most clearly in <FIG>, each contact ring segment <NUM> of the collet <NUM> presses the sidewall <NUM> of the plunger <NUM> radially outward. Such outward radial force may force the front wiper ring <NUM> and/or rear wipe ring <NUM> radially outward to provide an increased sealing force against the inner wall <NUM> of the sealant cartridge <NUM>. When the contact ring segments <NUM> are forced radially outward, they may contact the plunger sidewall <NUM> at any desired location(s) along the axial length of the plunger <NUM>. Such additional sealing force may reduce or eliminate unwanted leakage of the sealant contained in the cartridge around the outer periphery of the plunger <NUM>. Thus, outward expansion of the collet <NUM> creates a tighter seal between the plunger <NUM> and inner cartridge wall <NUM> to prevent sealant bypassing the plunger head assembly. The outward expansion during application of the sealant allows the plunger head assembly <NUM> to provide an optimal seal with different plunger designs and cartridges.

The collet <NUM> may expand to have a radially extended diameter greater than the inner diameter of the sidewall <NUM> of the plunger <NUM>, but less than or substantially equal to the inner diameter of the inner wall <NUM> of the cartridge <NUM>. The collet <NUM> may expand to a range of diameters to allow for the use of different sized/designed sealant plungers and apply necessary pressure between the plunger and the inner wall of the cartridge to prevent sealant bypass.

When the collet <NUM> is in its radially retracted position, it has a retracted outer diameter, and when the collet <NUM> is in its radially expanded position, it has an expanded outer diameter. The expanded outer diameter is typically at least <NUM> percent greater than the retracted outer diameter, for example, at least <NUM> percent greater, or at least <NUM> percent greater. The expanded outer diameter of the collet <NUM> is typically less than <NUM> percent greater than the retracted outer diameter, for example, less than <NUM> percent greater, or less than <NUM> percent greater. The expanded outer diameter of the collet <NUM> may typically range from <NUM> to <NUM> percent greater than the retracted outer diameter, for example, from <NUM> to <NUM> percent greater, or from <NUM> to <NUM> percent greater.

For certain sealant cartridge <NUM> and plunger <NUM> sizes, the expanded outer diameter of the collet <NUM> may range from <NUM> to <NUM> millimeters, for example, from <NUM> to <NUM> millimeters, or from <NUM> to <NUM> millimeters, or from <NUM> to <NUM> millimeters, or from <NUM> to <NUM> millimeters. However, the expanded outer diameter may be adjusted for other sizes of sealant cartridges and plungers.

In the figures, the collet <NUM> comprises ten contact ring segments <NUM>, but any other suitable number of segments may be used, e.g. four, six, eight, twelve or more segments. Alternatively, the collet <NUM> may comprise a single segment. The segments <NUM> may be equally sized and spaced, or any other suitable arrangement may be used. For example, adjacent segments may have different radial lengths and/or widths.

The expandable plunger head assembly <NUM> may be used with conventional powered sealant dispensing guns such as battery-powered, electrically powered and pneumatically powered dispensing guns (not shown) or may be used with conventional manual mechanical style sealant dispensing guns (not shown).

The components of the expandable plunger head assembly <NUM> may be made of any suitable materials such as plastics, metals and the like. For example, the ram head <NUM> may be made of a rigid material such as aluminum, stainless steel, polypropylene or the like, and the collet <NUM> may be made of a semi-rigid or flexible material such as nylon, polypropylene, polyethylene and the like.

For purposes of the detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be read as if prefaced by the word "about," even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open-ended numerical range is described herein, all numbers, values, amounts, percentages, subranges and fractions within or encompassed by the numerical range are to be considered as being specifically included in and belonging to the original disclosure of this application as if these numbers, values, amounts, percentages, subranges and fractions had been explicitly written out in their entirety.

As used herein, "including," "containing" and like terms are understood in the context of this application to be synonymous with "comprising" and are therefore open-ended and do not exclude the presence of additional undescribed or unrecited elements, materials, ingredients or method steps. As used herein, "consisting of" is understood in the context of this application to exclude the presence of any unspecified element, ingredient or method step. As used herein, "consisting essentially of" is understood in the context of this application to include the specified elements, materials, ingredients or method steps "and those that do not materially affect the basic and novel characteristic(s)" of what is being described.

As used herein, the terms "on," "onto," "applied on," "applied onto," "formed on," "deposited on," "deposited onto," mean formed, overlaid, deposited, or provided on but not necessarily in contact with the surface. For example, an electrodepositable coating composition "deposited onto" a substrate does not preclude the presence of one or more other intervening coating layers of the same or different composition located between the electrodepositable coating composition and the substrate.

Claim 1:
A radially expandable plunger head assembly (<NUM>) for use in a sealant cartridge assembly including a sealant-containing cartridge (<NUM>) and a plunger (<NUM>) slidably mounted inside the sealant-containing cartridge (<NUM>), the plunger head assembly (<NUM>) comprising:
a ram head (<NUM>) slidingly mounted on a front end (<NUM>) of a plunger rod (<NUM>) having a front face (<NUM>) structured and arranged to contact a front plunger end (<NUM>), and a rear collet engagement surface (<NUM>); and
a radially expandable collet (<NUM>) mounted on the front end (<NUM>) of the plunger rod (<NUM>) having at least one radially expandable finger (<NUM>) structured and arranged to contact the collet engagement surface (<NUM>) of the ram head (<NUM>) and move radially outward toward a sidewall (<NUM>) of the plunger (<NUM>) when the plunger rod (<NUM>) is advanced forward inside the sealant-containing cartridge (<NUM>);
characterized in that the plunger (<NUM>) comprises a front wiper ring (<NUM>), and the at least one radially expandable finger (<NUM>) of the collet (<NUM>) contacts the plunger at an axial location adjacent to the front wiper ring (<NUM>), and in that the at least one radially expandable finger (<NUM>) of the collet (<NUM>) comprises a ram-engaging inner surface (<NUM>) and an outer contact ring segment (<NUM>).