US2933221A - Dispensing gun structure - Google Patents

Description

H. ,L RAND ETAL Filed Feb, 28, 195? DISPENSING GUN STRUCTURE April 19, 1960 DISPENSING GUN STRUCTURE Henry J. Rand, Bratenahl, and Herman S. Lehner, Kirtland Township, Willoughby, Ohio, assignors to The Gibson-Humans Company, Cleveland, iiio, a corporation of Ohio Application February 28, 1957, Serial No. 643,000

Claims. (Cl. 222-391) The present invention relates to dispensers of the type generally known as calking guns or dispensing guns and is most particularly adapted to a dispensing gun structure designed to be used with interchangeable cartridges of the material to be dispensed. However, the invention is not necessarily limited to applications where interchangeable cartridges are employed.

The invention may be embodied in a dispensing cartridge in the form of a paper, metal or plas-tic tube having at one end an internal cap or piston adapted to -act as a plunger to express calking material or the like and at ,the other end a discharge opening through which expressing takes place. Frangible or removable sealing means may be provided at the cartridge o-r at both ends of the cartridge. The cartridge may form a convenient shipping container for the material to be dispensed.

The invention is not limited to devices for dispensing calking compound as such, but it is generally applicable to devices for dispensing g-reases, printing inks, confectionery mixes, plastic materials and the like. However, since the invention presently appears to have its most promising application in calking gun structure, it will be described with particular reference thereto.

A difiiculty encountered in the ruse of calking guns is"` that calking compound tends to continue to flow out the t discharge end of the gun after gun actuation is discon-4 tinued. This afterow is in part the result of the deformation ot the wall of the cartridge during gun actuation, due to the pressure to which the compound is subjected. The Wall, in returning to its funstressed conformation when actuation is discontinued, pumps an additional unwanted increment of compound through the discharge chamber. This action is augmented by whatever compressibility the calking compound itself may have. Aftertlow of the calking compound is wasteful and messy and, therefore, very undesirable.

Various attempts have been made to eliminate or minirnize this afterow. Devices have been made in which the internal cap or piston comprises a rigid annulus which surrounds and is fixed to a central lexible web which is readily capable of substantial deformation by expanding in arearward direction upon relief of expressing force. However, some of these devices require a special shape of head on the actuating rod which supplies the expressing force to the piston. They also involve close manufacturing tolerances and corresponding problems' of quality control in manufacture. All of the devices of the prior art which are of the ilexible web type have what may be referred to as a displacement-expansion ratio which is relatively high. This ratio is the ratio of l) the amount of linear displacement of the actuating rod which is necessary to accommodate the rearward expansion to (2) the amount by which the volume increases incident to the rearward expansion. The relatively high value of this ratio is due to the fact that such devices are incapable of backward expansion in the vicinity of their in the vicinity ot their center, and the cross-sectional area ICC in the vicinity of the periphery is, of course, far greater than the cross-sectional area in the vicinity of the center. This high displacement-expansion ratio exaggerates the undesirable eiects of iiictional resistance of the actuating rod to the rearward expansion of the exible wall of the piston, or, in those cases where the propelling pressure is relieved by positively moving the actuating rod backwards, the amount of positive backward movement which is necessary is relatively high. In this connection it should be understood that the piston structure contemplated by the invention may be employed with guns in which the exp-ressing force on the pusher lrod or actuating rod which drives the piston structure is merely relieved at the conclusion of gun actuation or with guns in which the pusher rod or actuating rod is positively shifted backwardly at the conclusion of gun actuation.

Devices have been provided in which the displacementexpansion ratio is relatively low. Such devices involve a piston having a rigid annulus which surrounds a rigid central wall which is axially slidable with respect to the annulus. However, this type of device involves as much or more frictional resistance to rearward expansion as do the prior art devices discussed in the preceding paragraphs. This is due to the fact that the friction between the central wall and `the annulus is as great or almost as great as the friction -between the periphery of the piston and the sides of the tube or cartridge in which the piston i An object of Ithe present invention is to minimize or f eliminate afterow by providing means which involve a relatively low displacement-expansion ratio and which at the same time involve only a relatively low frictional resistance to rearward expansion.

Another object of the invention is to provide such a device in which sealing engagement of the piston with the tube during the expressing operation is tighter and more positive than in those of the prior art even though frictional resistance to rearward expansion is less than that of prior art devices.

Another object of the invention is to provide anti-afterflow means which acts in such :a way that rearward expansion is aided by the release of stored energyother than and in addition to that stored-in the stressed walls of the tube or in the compressed calking compound.

These objects and advantages of the invention are achieved by the provision of a piston structure comprising a piston body having a reduced and tapered `shoulder on which is received an axially displaceable annular elastic member.

In a preferred form, the advantages of the invention are to the remainder of the piston structure as to accomplish a significant degree of elastic deformation and corresponding energy `storage without tending to snub on the tapered shoulder on which it is received..

The several objects, `advantages and features of the invention notedabove are all subservient to the general and obvious purpose of the invention which is to accomplish improvements in design and function of calking gun devices which will tend to stimulate sales of these device-s and their use by the consuming public. The following description of one particular embodiment of the inventionwill make it possible to better apprehend the subservient objects, advantages and features of the invention. The particular embodiment is illustrated in the drawings in which:

Figure l is a view, partially broken away, showing the o nomal operative position of a calking gun which embodies the invention.

Figure 2 is a cross-sectional view of an enlarged scale Patented Apr. 19, 1960 wise.

, showing such piston in the same attitude or condition which obtains in Figure 1.

Figure 3 is a View similar to Figure 2 but showing the piston in a different attitude or condition.

-ln the illustrated gun, a. calking compound Vcartridge l is inserted in lthe holder or bail il and is dischargedV out the end 12 through the discharge spout 13. The discharge end of the calking compound cartridge may contain a sealing diaphragm which is ruptured by insertion in the gun or by a separate puncturing tool or by the pressure which results when the gun is actuated. Alternatively, the discharge spout i3 may have a plug or cap which is removed when the gun is used. Other arrangements may be employed so that each cartridge 10 remains seated until it is actually used in the gun.

The calking compound cartridge is in the form of a paperboard,`metal or plastic sleeve and includes a sliding plunger or piston gener lly indicated at v1S and designed to be engaged by an endplate 16 xed to the gun actuating rod or ratchet bar 17 and, thus, to be displaced along the cartridge to express the compound from the discharge orifice.V Before and during use of the cartridge, the piston l may serve asa seal or closure for the end of the cartridge opposite tothe discharge end. Alternatively, a separate frangible or removable closure for such end may be employed.

The ratchet 'bar 17 is preferably circular in crosssection and may have a bent handle portion 18 at the rear end thereof. Ratchet teeth 19 are 'formed on one side of the bar 17. During gun actuation, the ratchet teeth 19 are engaged by a driving pawl 2t) and a holding pawl 2l.

The handle portion of the calking gun may comprise a handle body 25, to which the bail 11 is fixed, and a lever grip 26 which is pivoted tothe handle body at 27.

A large spring 28 urges the lever grip 26 to its open position. The driving pawl 20 is pivoted on the lever grip 26 at 29. The holding pawl 21 is pivoted on thc gun body at 3d. Both thesepawls are normally urged to ratchet engaging position in the conventional manner by suitably disposed wire springs (not shown for purposes of clarity).

It will be apparent that with the lratchet bar 17 in its illustrated position, actuation of the lever vgrip 26 will cause the driving pawl 2li to intermittently advance the ratchet bar 17, the ratchet bar being held in its advanced position by the holding pawl 21. However, when the ratchet bar is` rotated approximately a quarter of a turn or more by means of the handle 1S, it is released from engagement with either of the pawls, thereby relieving all expressing force and allowing the bm 17 to be shifted backwardly by the `back pressure on the piston 15 or allowing the bar 17 to be manually positively shifted backwardly by manipulation of the handle 18,V or other- It should be apparent that all or many of the above details are incidental to the present invention.

They are set forth so that one example ofthe present invention may be here disclosed in `association 'with the kinds of structural elements with which it may typically berassociated in actual practice.

The piston 15 comprises a piston body 3S which may be stamped from sheet metal or otherwise formed of metal or some other 'appropriate material. Extending radially inwardly Vfrom the circumference of the piston body 35 is `an annular shoulder 36. An annular surface 37 tapers from `a relatively great diameter adjacent the root ofthe annular shoulder 36 to a relatively reduced diameter. kAn annular elastic member 38 is received on the annular surface 37. The member 3S has in nondistended condition an inside diameter smaller than the great diameter ofV the annular surface 37. The member 38 projects radially outwardly sufficient-ly to sealingly engage the cylindrical inside wall of the cartridge it) i l 4 is the position of the .parts when expressing force is applied through the actuating means including the actuating rod 17 and its associated elements. Preferably, the parts are so dimensioned that sealing engagement obtains even when the member 38 is located over the smallest diameter of the annular surface 37, but in any event itwill be apparent that the tightest sealing engagement obtains when the member 38 is moved toward or to the shoulder 36. Y

The tapering annular surface 37 may have an extension 39 which may not be tapered in the same way or, as shown, may not be tapered at all. The ring 38 is retained by a radially projecting shoulder 40 land the piston body is completed in the illustrated example by a central Wall 41.

ln the particular example of theinvention which is illustrated in the drawings, the member 38 has the shape of a toroid of essentially square .small cross-section (taken on planes extending axially). This presently appears to be a preferable shape. As the torus is displaced, its outermost leading edge wipes the inside of the container, establishing a line seal. For example, theleading outer edge A of the ring 3S as shown in Figure 2 will establish line contact when the piston 1S is advanced Yto dispense material@ The Vdistendiug of the ring in this condition involves to a considerable extent stresses which are selfcontained within the ring itself or stresses which react through the annular shoulder 36 without reaction through the annular surface 37. To the'same considerable extent, any tendency toward snubbing engagement between the ring and the surface 37 is avoided. Thus, energy stored in distending the ring 38 during application of expressing force through the actuating rod 17 and other actuating elements is most effectively utilized to augment back pressure caused by stressing of the walls of the con-` tainer 10 and the compressibility of the material being dispensed.

The leading outer edge B will establish line Contact whenrearward expansion and rearward movement of theV piston occurs. However in this case, the distending of the ring yis much less. In fact, due to the taper Vof the surface 37, the ring moves backwardly Vonly a short distance during initial rearward Vexpansion of the piston, andthe balance of the rearward expansion'is accomplished essentially by the piston body alone. The final position of the parts after expansion has occurred is indicated in Figure 3.

It will now be fully apparent that the illustrated in-V vention involves a relatively low.displacement-expansion ratio and at the same time involves only a relatively low -friction between the periphery of the piston and the sides of the `tube or cartridge during rearward expansion.

It will be appreciated that forms of the invention which presently appear to beV kpreferable have been illust/rated and described in this specification. Obviously, 'modifications and alterations differing slightly or even radically kin 'appearance from those herein describedv'vill occur to Y,others on seeing this specification or other disclosures off' the invention, such as commercial embodiments thereof.

diameter adjacent the root of said vannular shoulder'to 'a relatively reduced diameter, an annular elastic member received on said annular tapered surface'and having in non-distended condition an inside diameter smaller than said great diameter, said annular elastic member projecting radially outwardly suiciently to sealingly engage the wall of said cylindrical chamber with the tightest sealing engagement obtaining when the annular elastic member is adjacent said shoulder, and radially projecting retaining means on the axially opposite side of said annular elastic member from said shoulder, said shoulder and said retaining means being spaced apart suiciently to accommodate relative axial translation of said piston body with respect to said annular elastic member, said annular elastic member annularly continuously sealingly engaging said annular surface throughout said relative axial translation.

2. A calking assembly comprising a cylindrical cartridge having, at its respective rear and front ends, a piston and a dispensing spout, said piston being received within the cartridge so as to seal the cartridge and so as to remain at progressively advanced positions toward said spout, a calking gun for supporting said cartridge, said gun being provided with an axially movable plunger to engage said piston whereby calking material in said cartridge is expressed under pressure through said spout responsive to axial movement of said piston toward said spout, said piston comprising a piston body, an annular shoulder extending radially inwardly from the circumference of said piston body, an annular surface tapered from a relatively great diameter adjacent the root of said annular shoulder to a relatively reduced diameter, au annular elastic member received on said annular tapered surface and having in non-distended condition an inside diameter smaller than said great diameter, said annular elastic member projecting radially outwardly suiciently to sealingly engage the wall of said cylindrical cartridge with the tightest sealing engagement obtaining when the annular elastic member is adjacent said shoulder, and retaining means projecting radially outwardly at an axial location which, with reference to said shoulder, is on the opposite side of said annular elastic member, said shoulder and said retaining means'being spaced apart sutliciently to accommodate axial translation of said annular elastic member relative to said piston body between said shoulder and said retaining means, said annular elastic member annularly continuously sealingly engaging said annular surface throughout said relative axial translation.

3. A calliing assembly comprising a cylindrical cartridge having, at its respective rear and front ends, a piston and a dispensing spout, said piston being received within the cartridge so as to seal the cartridge and so as to remain at progressively advanced positions toward said spout, a callting gun for supporting said cartridge, said gun being provided with an axially movable plunger to engage said piston whereby calking material in said cartridge is expressed under pressure through said spout responsive to axial movement of said piston toward said spout, said piston body having an annular shoulder, an annular surface tapered from a relatively great diameter adjacent the root of said annular shoulder to a relatively reduced diameter, an annular elastic member received on said annular tapered surface and having in non-distended condition an inside diameter. smaller than said great diameter, said annular elastic member projecting radially outwardly suiliciently to sealingly engage the wall of said cylindrical cartridge with the tightest sealing engagement obtaining when the annular elastic member is adjacent said shoulder, said annular surface being of sufficient length to accommodate axial translation of said elastic annular member relative thereto and said elastic annular member being axially translatable along said annular surface, said annular elastic member annularly continuously sealingly engaging said annular surface throughout said relative axial translation.

4. A callcing assembly comprising a cylindrical cartridge having, at its respective rear and front ends, a piston and a dispensing spout, said piston being received within the cartridge so as to seal the cartridge and so as to remain at progressively advanced positions toward said spout, a calking gun for supporting said cartridge, said gun being provided with an axially movable plunger to engage said piston whereby calking material in said cartridge is expressed under pressure through said spout responsive to axial movement of said piston toward said spout, said piston comprising a piston body, an annular shoulder extending radially inwardly from the circumference of said piston body, anannular surface tapered from a relatively great diameter adjacent. the root of said annular shoulder to a relatively reduced diameter, an annular toroidal elastic member of essentially square small cross-section received on said annular tapered surface and having in non-distended condition an inside diameter smaller than said great diameter, said annular elastic member projecting radially outwardly sufficiently tosealingly engage the wall of said cylindrical cartridge with the tightest sealing engagement obtaining when the annular elastic member is adjacent said shoulder, and radially projecting retaining means on the axially opposite side of said annular toroidal elastic member from said shoulder, said shoulder and retaining means being spaced apart suiciently to accommodate axial translation of said elastic member, relative to said piston body between said shoulder and said retaining means, said annular elastic member annularly continuously sealingly engaging said annular surface throughout said relative axial translation.

5. A dispensing device comprising a cylindrical chamber having a discharge orice at one end, a piston movable axially through said chamber toward said orifice, actuating means for advancing said piston, said piston comprising a piston body having an annular shoulder,

an annular surface tapered from a relatively great diameter adjacent the root of said annular shoulder to a relatively reduced diameter, an annular elastic member received on said annular tapered surface and having in non-distended condition an inside diameter smaller than said great diameter, said annular elastic member projecting radially outwardly sufficiently to sealingly engage the wall of said cylindrical chamber with the tightest sealing engagement obtaining when the annular elastic member is adjacent said shoulder, said annular surface being of suicient length to accommodate axial translation of said annular elastic member and said piston body relative to each other, said annular elastic member being axially translatable along said annular surface, said annular elastic member annularly continuously sealingly engaging said annular surface throughout said relative axial translation.

References Cited in the le of this: patent UNITED STATES PATENTS

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