US3059635A - Respirator collar - Google Patents

Description

Oct. 23V, 1.962 w. G. KUBICEK RESPIRATOR COLLAR Filed Nov. 7, 195e 3 Sheets-Sheet 1 INVENroR. h//LL/AM 6.Y KUB/@EK /lrroR/VEYS W. G. KUBICEK RESPIRATOR COLLAR Oct. 23, 1962 3 Sheets-Sheet 2 Filed Nov. 7. 1958 JNVENToR. l//LL/AM 6, KUB/@EK ATTORNEYS Oct. 23., 1962 w. G. KUBICEK RESPIRATOR COLLAR 3 Sheets-Sheet 3 Filed NOV. '7, 1958 INVENTOR.

WML/,4M 6, Ku/GEK ATTORNEYS United States Patent O 3,059,635 RESPERATR CLLAR William G. Kuhicek, Rosemount, Minn., assigner to l. Il.

Monaghan Company, Inc., Denver, Colo., a corporation of Colorado' Filed Nov. 7, 1955, Ser. No. 772,605 17 Claims. (Cl. lZ--Sm This invention relates to respiratory apparatus and, more specifically, to improved collars for use therewith.

Patients suffering from any one of a number of different diseases or other aillictions wherein breathing by normal muscular action becomes difficult or substantially impossible, are frequently confined within automatic respirators operative to effect cyclic inflation and deflation of the lungs at predetermined time intervals. These devices customarily include a nearly air-tight shell which encases at least the patients chest and within which alternating positive and negative pressures of the order of one-half pound per square inch or less above and below atmospheric pressure are applied to the outside of the body `for inflating and deflating the lungs. The patients head is usually located outside the unit which, of course, requires that a substantially air-tight seal be maintained at the point where the body emerges from the shell. Thus, a flexible collar is ordinarily provided encircling the neck in air-tight sealed relation thereto and to the front wall of the body or chest shell from which it depends.

The prior art collars for this purpose have, however, proven deficient in several respects. First of all, one of the widely used designs comprises a thick sheet or disk of sponge rubber having an opening therein sized to lit snugly around the patients neck but which requires that the material be stretched to the point where the opening is large enough to pass over the patients head. With an adult, this factor is not of critical importance although it causes considerable discomfort while the patients head is being forced through the small opening. When used for infants, on the other hand, a collar of this type actually becomes dangerous to apply because of the likelihood of damage to the soft cranial area as the head is forced therethrough, and because the size of an infants head is much larger in proportion to its neck than that of an adult which requires that material of the collar be stretched even more tightly in order to enlarge the opening suiciently.

Another serious disadvantage of the sponge rubber collar is its thickness and again, this problem becomes most acute in infant collar applications, especially premature infants. The face area of these collars is frequently as much as twenty square inches or more and they are seldom, if ever, less than ten square inches in area. This means, of course, that even at differential pressures which do not exceed one-half pound per square inch, the total pressure applied against the collar can easily be in excess of the weight of a premature infant which is oftentimes less than five pounds. Thus, an unreinforced flexible collar will act as a diaphragm under the alternating positive and negative pressures applied thereagainst from inside the shell causing the infant to move back and forth as it iiexes which results in severe abrasions to the childs tender skin. A degree of rigidity, or at least inilexibility, can be realised by making the collar thick enough to resist the differential pressures to which it is subjected without appreciable flexing; however, this does not solve the infant collar problem as the linear distance between the inside face of the front tank or shell wall and the outside surface of such a thickened sponge rubber disk becomes considerably greater than the total length of a babys neck which is frequently P lCC no longer than a half-inch or less. It is, therefore, important that infant respirator collars be designed to provide a thin relatively rigid wall adapted to encircle the neck without appreciable flexing under the influence of differential pressures applied thereto.

Still another limitation of sponge rubber collars is that they are likely `to cause severe skin abrasions on the neck of the wearer. Patients are usually confined to respirators of this type for extended periods of time and as the head and neck are turned within the collar, the skin rubs against the edge of ythe opening therethrough producing ulcers. Little can be done to relieve these conditions as the collar cannot -be relocated on another portion of the body nor can the patient be removed from the respirator for a sufficient length of time to allow the damaged areas to heal. The skin of a new born infant is especially tender and subject to considerable damage from even a slight amount of chang.

A problem also arises in connection with mounting an unreinforced sponge rubber collar on the front wall of the tank `or shell of the respirator in a manner to permit movement of the head and neck `from side-to-side and up and down. It is obviously impossible for a patient, infant or adult, to lay within the respirator without moving the neck toward the edges of the collar. When this happens, it is advisable to have the collar mounted on the v front wall of the tank so that it Will shift with the patient thus maintaining the neck nearly centered within the opening in the collar. Such a condition, however, is extremely difcult to achieve with a completely flexible sponge rubber collar.

The only other type of respirator collar in common use and which requires specific mention is the one that comprises a plurality of overlapping relatively rigid segments mounted for slidable movement over one another in much the same manner as an iris diaphragm to Vary the diameter of the neck-receiving opening. This collar is subject to many of the same objections as the sponge rubber one in that it also must be passed over the head of the wearer and can cause severe skin abrasions. The latter problem becomes especially serious as the rigid leaves or segments are in direct contact with the neck and provide little or no relief from chatting. Probably the most difficult problem, however, is maintaining an air-tight seal around the neck of the wearerwithout having to squeeze it so hard that the collar becomes eX- tremely uncomfortable.

It is, therefore, the principal object of the present invention to provide an improved collar for use with respiratory devices of the type in which a portion of the patients body is encased within an air-tight tank or shell.

A second object is the provision of a collar of the type described which is ideally suited for use around the necks of infants which must be confined within a respirator.

A third objective is the provision of a respirator collar that is thin-walled yet reinforced with a rigid skeletal element adapted to resist deflection under the influence of positive `and negative pressures applied against the face thereof.

A fourth object of the invention is the provision of a collar for use with a respiration unit that can be opened for insertion of Ithe wearers neck thus eliminating the problem of passing it over the patients head.

A fifth objective is to provide a neck-receiving seal which can be attached to the front wall of a respirator in a manner to permit relative slidable movement therebetween in a plane normal to the 4centerline of the neck opening so that a patient confined therein can move his or her head from side-to-side as well as up and down.

Another object of the invention is the provision of a` respirator collar that includes a segmented skeletal reinforcing ring which can be broken at one point and opened to admit the neck.

Still another object is the provision of a reinforcing ring having aplurality of pivotally interconnected segments adapted to have successive portions of their outside edges removed and additional segments added therebetween in order that the outside diameter thereof will remain substantially constant while the inside diameter increases to accommodate flexible sealing disks and annular envelopes having central openings of various sizes.

An additional object of the invention is to provide a respirator collar which includes an annular cuff of soft flexible material formed around the inside edge of the central opening in a sealing element reinforced with a rigid skeletal member.

Further objects are to provide a respirator collar which is simple to operate, inexpensive to manufacture, versatile, adaptable for both adult and infant use, one that is comfortable and soft against the neck of the wearer, and a device of the class described that maintains a substantially air-tight seal around the neck yet, which permits relatively free movement of the patient without the usual chaing of the skin.

Other objects will be in part apparent and in part pointed out specifically hereinafter in connection with the description of the drawings that follow, and in which:

FIGURE 1 is a perspective view showing the improved respirator collar of the present invention in place around the neck of an infant who is confined within the tank or shell of a respirator;

FIGURE 2 is a front elevation to an enlarged scale showing the respirator collar in detail, portions thereof having been broken away to better show the construction;

FIGURE 3 is a diametrical section taken along line 3-3 of FIGURE 2, the front wall of the respirator shell having been shown in dotted lines;

FIGURE 4 is a fragmentary section to a further enlarged scale taken along line 4-4 of FIGURE 2 showing the closure for the collar;

FIGURE 5 is a fragmentary section taken along line 5 5 of FIGURE 2 to an enlarged scale and showing the pivotal connection between the segments of the skeletal member that forms a part of the collar;

FIGURE 6 is a view similar to FIGURE 2 but showing the collar in open position to receive the patients neck;

FIGURE 7 is a fragmentary front elevation of the skeletal element with the coating thereon removed to expose the construction of the segments;

FIGURE 8 is a view similar to FIGURE 2, but to a slightly reduced scale, showing a modified form of the respirator collar of the present invention;

FIGURE 9 is a diametrical section similar to FIGURE 3 taken along line 9-9 of FIGURE 8;

FIGURE l0 is a view similar to FIGURE 6 showing the skeletal element of the FIGURE 8 modication in open position;

FIGURE 1l is an enlarged fragmentary section taken along line 11-11 of FIGURE 8 showing the closure of the modied form; and,

FIGURE l2 is a view similar to FIGURES 2 and 8 showing the skeletal member broken off around its peripheral edge and a segment added to provide an enlarged central opening therein.

Referring now to the drawing and in particular to FIG- URE l thereof, it will be seen that the respirator collar of the present invention, which has been identified broadly by the numeral 10, .encircles the neck of the patient 12 in substantially air-tight sealed engagement therewith and is also in sealed contact with the front wall 14 of the tank or body shell 16 of respirator IS. At this point it should be mentioned that although the collar has been illustrated in use on the neck of a baby confined within an infant respirator which is by far the most critical and diicult application of the device, its use is by no means limited to this specific environment and it is equally well-suited to adult patients and other types of respirators. The specific infant respirator shown will be seen to comprise a two-part body shell, the upper part 20 of which is removable so that the body of the infant may be laid on a bed (not shown) located in the lower part 22. A head rest 24 depends from the front wall of the lower part and provides means for supporting the patients head so that the neck will be centered within central opening 26 formed in the front of the tank and which can be best seen in FIGURE 3. Pressurizing means, which have not been illustrated, are provided for establishing alternating positive and negative pressure conditions inside the air-tight body shell cycled to the patients normal breathing rate and adapted to expand and contract the lungs in the well known manner.

`With reference to FIGURES 1 and 3, it will be seen that the central opening 26 in the front wall 14 of the body shell 16 is considerably larger than the patients neck and is encircled by a forwardly projecting annular rib 23 that cooperates with said opening to define a recessed and substantially planar annular sealing surface 3h against which the collar rests. A plurality of angularly spaced spring clips 32 have been shown located on the rib 28 in position to overlay the outside surface of the collar 10 and hold it in air-tight sealed contact with recessed surface 39. Note, however, that the outside diameter of the collar It), and especially of rigid skeletal element 34 thereof, is somewhat less than the inside diameter of annular rib Z8, and that spring clips 32 are each preferably provided with a spherical element 36 or some other low-friction contact which permits the collar to slide over the face of recessed surface 30 in any direction for a limited distance. This feature is quite important as it permits the patient to move his head and neck from side-to-side and up or down relative to the central opening 26 in the front wall of the tank without disturbing the neck-seal provided by the collar which merely slides across the face of the recessed surface until the rigid skeletal element contacts the annular rib.

`In FIGURES 2-6, inclusive, wherein the first of the specific embodiments of the respirator collar 10 has been illustrated, it will be seen to include rigid skeletal element 34 attached to the front face of a flexible, and preferably elastic, disk-like sealing element 38 with a suitable adhesive. This disk is substantially at, circular and provided with a centrally-located neck-receiving opening 40 surrounded by an integrally-formed annular cuff 42 sized to engage and seal against the neck of the patient. Element 38 is also split to provide free ends 44 and 46 which overlap one another in the normally closed position of FIG- URES 2, 3 and 4; yet, which can be separated as shown in FIGURE 6 to open the collar so that the patients neck can be passed therebetween into opening 40. In addition, free end 44 of sealing disk 38 is preferably formed to provide a loop 48 adapted to receive the other free end 46 which is passed beneath web 5t) that integrally interconnects cuff 42 with the outside peripheral edge.

The material from which the sealing disk is fabricated is not critical although, as aforementioned, it must be flexible so that the collar can be opened and is also preferably elastic. Certain types of rubber and plastic rr1aterials, especially those which can be impregnated with carbon and rendered conductive for use in an explosive atmosphere or environment, have been found quite satisfactory. The material selected should also be one that is soft, pliable, smooth, lightweight, moldable and which will not irritate the skin.

Before proceeding with a detailed description of the skeletal elment 34 of the collar, it will be well to mention a few other salient features of the sealing disk 38. First of all, the exible nature of the disk is such that a negative pressure inside the tank of the respirator will face 30 on the front wall 14. Under a condition of positive pressure inside the tank, spring clips 32, of course, bias the sealing disk into the same sealed relationship with surface 30.

The cuff 42 encircling the neck-receiving opening 40 extends forwardly and is rounded to place as smooth a surface in contact with the patients neck as possible. Elimination of the cuff, of course, would place the relatively thin edge of the disk against the patients neck which would likely cause severe and painful skin abrasions or at least considerable irritation. Note also, that the overall thickness of the assembly which includes the front wall 14 of the tank and the cuff 42 of the collar still remains relatively small and easily capable of fitting on even the short neck of a premature infant, especially when the fact that the cuff can be compressed and shortened is considered. -In addition, the construction which enables the ends 44 and 46 to be overlapped to a greater or less extent is of prime importance as this feature permits the size of the neck-receiving opening 40 to be varied wtihin certain limits thus insuring that a close but comfortable fit of the cuff around the patients neck can be achieved. Fnally, the cuff is formed sufficiently thin and pliable to conform readily with the patients neck and provide an air-tight seal therewith irrespective of any irregularities that may exist therein.

Now, it has already been mentioned briefly that a fully flexible membrane or diaphragm, such as sealing disk 38 considered alone, would present sufiicient surface area even at nominal pressures of one-half pound per square inch or less above or below atmospheric to shift an infant Within the respirator; therefore, if the thin, lightweight and pliable design of element 38 and cuff 42 which is so desirable is to be maintained, it is important that adequate reinforcement thereof be provided and this end is achieved through the use of rigid Skeletal element 34. This element comprises a plurality of generally trapezoidal-shaped segments 54 having ears 56 projecting from one side edge thereof that are offset slightly and overlap the adjacent segment to which they are pivotally attached by means of fasteners 58. The inner and outer edges 60 and 62, respectively, `of each segment or link 54 are preferably arcuate and shaped to conform generally to the cuff and peripheral edge of the sealing disk 38, but in spaced relation thereto as shown. The space left between the cuff 4Z and inner edge 60 of the several segments is especially important as it provides the soft pliable cushion which engages the patients neck and prevents it from coming in contact With the rigid skeletal element.

Each segment is formed from a relatively thin rigid material and is substantially flat except for the ear which is offset approximately its thickness so that when several are joined together in overlapping relation, the skeletal element thus formed will have a large planar surface adapted to lay against the outer face of the sealing disk. In the open-faced form of the respirator collar illustrated ing FIGURES 2-6, inclusive, of the drawing, the skeletal element is cemented or otherwise securely attached -to the front face of the sealing disk with the exception of the ears 56 of the several segments which may be spaced slightly therefrom due to their offset construction. A small space or gap such as that shown at 64 in FIGURE 5 between the ear and adjacent portion of the sealing disk is not harmful and, in fact, may have certain advantages in maintaining the rear face 38 of the collar fiat and permitting the flexible disk to fold between the segments when the ends are spread apart to pass the neck into the cuff.

The intermediate segments 54a of the skeletal element 34 are identical and can be considered as more or less permanently attached to one another as well as to end segments 54b and 54e. These last-mentioned end segments, on the other hand, are modified slightly to provide for a detachable connection therebetween. Segment 54b is located on the sealing disk adjacent free end 44 thereof; whereas, segment 54e is positioned at the other end 46. Ear 56b of segment 54b is provided With a pluralty of openings 66 spaced in the direction of the length thereof and each of which is adapted to receive pin `6ft that projects outwardly from the face of segment 54C. Thus, by selectively locating pin d within one of the openings 66 of segment 54h, minor adjustments in the size of neckreceiving opening 4f) can be made to provide the optimum fit while the degree of overlap between ends '44 and 46 is varied to conform thereto. Also, this same detachable connection between the end segments of the skeletal element make it possible to open the collar so that it can be placed around the neck as shown in FIGURE 6.

Now, before proceeding with the detailed description of certain other embodiments of the respirator collar of the present invention, it should be explained that while the skeletal element 34 of the open-faced design of FIG- URES 2-6 has been shown covered With a conductive coating 70, such as carbon-impregnated rubber, this Would only be required for use in certain highly explosive atmospheres as, for example, in a hospital operating room. For most general applications, on the other hand, a conductive coating would not be required although some type of finish that can easily be sterilized would certainly be preferred.

Referring now to FIGURES 7 and l2 of the drawing wherein a slightly modified embodiment of the openfaced collar has been illustrated and identified broadly by reference character 16m, it will be seen that the sealing disk 38m includes an enlarged neck-receiving opening y40m encircled by a correspondingly enlarged cuff 42m although the outside diameter thereof remains substantially the same. The reason for the modified sealing disk 38m is, of course, to accommodate patients with larger necks and it is obvious that no invention lies in making these elements in various sizes; however, the modified skeletal element 34m used with disks of different sizes is considerer unique. Skeletal element 34m, as modified, is fabricated from segments or links 54m, each of which includes at least one, and preferably several, generally arcutate fracture lines 72 spaced at various distances inside the outside edge 62 thereof. This design makes it possible to use one size segment to form several sizes of `collars differing from one another in the diameter of the neck-receiving opening 40. For example, removing piece 74 from each of the segments 54m in FIGURE 7 by breaking the rigid material along outer fracture line 72a, will produce the segment shown in FIGURE 12. Then, by pivotally interconnecting six, rather than five, of these segments together, a skeletal element 34m is formed which is sized to fit modified sealing disk 33m which includesV the enlarged central opening 40m. Itis important to note in this connection that the outside diameter of the skeletal element remains substantially the same while the inside diameter is increased due to the addition of one or more extra segments to the assembly. Thereafter, the skeletal element 34m is cemented to the disk 38m in the usual manner in either the coated form of FIGURE 7 or the uncoated form of FIGURE l2. Obviously, the open-faced respirator collar of FIGURE l2 is preferably factoryassembled because of the fact that it is necessary to cement the skeletal element to the sealing disk; however, in the closed-faced collar design which will be described shortly wherein the skeletal element may be loosely confined within the envelope-type sealing disk, the segments can -be altered in the field for use `in producing collars of various sizes.

Finally, referring to FIGURES 8 through l1 of the drawing, the last of the specific embodiments of the infant collar of the present invention illustrated herein will be described and denominated the closed-faced model 100. The flexible sealing disk 380 is modified to include double walls and is, therefore, generally tubular in cross section. The second wall is actually a continuation or extension of web 50 of disk 38 which interconnects the cuff 42 with peripheral edge 62 and, accordingly, has been identified by numeral 50m. This second wall 50m is integrally-formed and completely encircles cuff 42 and opening 40. The end i6 of this embodiment of the sealing disk 33% telescopes inside of end i4 as clearly shown in FIGURES 8 and ll, which, of course, means that the collar can be opened in the same manner as collar to receive the neck of the patient. 'Ille only other differences are the inclusion of a slot 76 and an opening 78 in the second wall 50m of the disk 38), the locations and purposes of which Will be described shortly.

Now, either skeletal element 34 or 34m which includes the fracture lines 72 in each segment, can be used inside sealing disk 380 and need not be cemented or otherwise attached thereto as was the case with the open-faced design as it is fully restrained by reason of the tubular construction. Note in this connection that the outside edge of the skeletal element cooperates with the outside edge of the disk to maintain the neck-receiving opening 4f) centered and spaced within the inside edge 6! of said skeletal element which is, therefore, prevented from contacting or pressing against the patients neck.

Another type of skeletal element designated by reference character 340 has, however, been shown used with sealing disk 38d. The segments 540 are modified to include a pair of ears 56d projecting outwardly from both sides thereof in opposite directions. Each of the intermediate segments Satta are pivotally connected to one another and to end segments 54011 and 54de by fasteners `58 which pass through the overlapping ears 560 thereof. One of the ears of each segment is offset slightly as before. Also, end segment 560e is provided with pin 68 which is positioned selectively within one of the openings 66 located in the other end segment 540i) to make slight adjustments in the size of neck opening 40. Slot 76 in the second wall 50m of desk element 380 is located to pass end segment Sb therethrough which prevents the skeletal element 340 from shifting rotarially therein. Opening 78 registers with the openings 66 in segment S/J to facilitate positioning the pin 68.

Now, it will be seen that even a collar used in an explosive atmosphere would not require that the entire skeletal element be protected with a conductive coating if it were encased within a sealing disk of the doublewalled tubular type 380 made from a conductive material. Only end segment 540b opens onto the outside of the sealing disk through slot 76; therefore, it is the only one which requires coating 70. Of course, the other segments may be coated if desired for sanitary purposes while, on the other hand, none of them require a coating if the unit is used in a non-explosive environment.

Last of all, it should be mentioned that skeletal element 340 can easily be modified to include fracture lines 72 of the earlier modification 34m. If this is done, the size of the skeletal element could be varied under eld conditions to adapt it for use with sealing disks 380 of different sizes as the skeletal element does not have to be cemented to the disk.

Having thus described the several useful and novel features of the present invention in connection with the accompanying drawings, it will be apparent that the several worthwhile objectives for which it was designed have been achieved. Although but a few Specific embodiments of the respirator collar have been shown and described herein, l realize that certain changes and modifications may occur to those skilled in the art within the broad teaching hereof; hence, it is my intention that the scope of protection afforded hereby shall be limited only insofar as said limitations are expressly set forth in the appended claims.

What is claimed is:

1. The collar which comprises, a flat-faced flexible ring element having a cuff surrounding the central opening therethrough, and a flat-faced rigid ring element having a plurality of pivotally interconnected segments arranged in annularly spaced relation around the cuff with the flat face thereof positioned to provide support for the flat face of the flexible element.

2. The collar as set forth in claim 1 in which both the rigid and flexible ring elements are split.

3. The collar as set forth in claim 1 in which the flexible ring element is formed from an elastic material.

4. The collar as set forth in claim 1 in which the flexible ring element is tubular and the rigid ring element fits inside thereof.

5. The collar as set forth in claim 2 in which the ends of the split-ring flexible element overlaps one another.

6. The collar as set forth in claim 2 in which the segments adjacent the split in the rigid ring element overlap and the pivotal connection therebetween is detachable.

7. The collar as set forth in claim 3 in which the rigid ring element is permanently attached to the face of the flexible elastic ring element.

8. A skeletal reinforcing element adapted for use as a support for a flexible sealing disk of a respirator collar or the like which comprises, a plurality of generally trapezoidal-shaped rigid plates having at least one ear projecting from a side edge thereof in offset parallel relation, each of ears overlapping an adjacent segment to which they are pivotally connected to form a substantially flat-faced ring.

9. The reinforcing element as set forth in claim 8 in which, each segment includes a pair of ears extending in opposite directions from opposite side edges thereof, one ear of each pair being offset to overlap the other ear of the adjacent segment to which it is pivotally connected.

10. The reinforcing element as set forth in claim 8 in which the pivotal connection between two of the adjacent segments is detachable to form a split ring.

11. The reinforcing element as set forth in claim 8 in which each of the segments includes a transverse fracture line in spaced substantially parallel relation to the peripheral edge thereof, said fracture line forming means for removing a portion of the segments to vary the diameter of the ring.

12. A collar of the type used in forming a' substantially air-tight seal between a patients neck and a pressurized tank of a respirator which comprises, a thinwalled flexible ring-like element having a flat face adapted for sealed engagement with a wall of a respirator tank and an outstanding cuff encircling the central opening ytherethrough sized `to receive a patients neck forming an annular seal therewith, and a skeletal ring-like reinforcing element formed from ia plurality of substantially flat rigid segments pivotally interconnected to one another and adapted to overlay the flexible element in annularly spaced relation around lthe outside of the cuff, said reinforcing element forming means operative to resist flexion of the flexible element in response to differential pressures applied to opposite faces thereof while permitting relatively free movement of the patients neck within the `cuff without contacting the rigid segments.

13. The collar as set forth in claim 12 in which the flexible ring-like element is split and two of the adjacent lsegments of the rigid ring-like element are detachably interconnected so that `the collar can be opened to receive the patients neck.

14. The collar as set forth in claim l2 in which the flexible ring-like element is formed from an elastic material.

15. The `collar as set forth in claim l2 in which the flexible ring-like element is single-walled and the rigid ring-like element is cemented or otherwise permanently attached thereto.

16. The collar as set forth in claim 12 in which the flexible ring-like element is tubular and the rigid ringlike element is freely supported inside thereof.

17. The collar which comprises, a flat-faced flexible ring element having 'a cul surrounding the central opening and a fiat-faced rigid ring element 'having ka plurality of interconnected segments arranged in annularly spaced relation around the cuff with the flat yface thereof positioned to provide support for the flat :face of the flexible ele-ment wherein the rigid ring element is constructed and arranged for selective circumferential 'adjustment relative to the central opening of the flexible element.

References Cited in the le of this patent UNITED STATES PATENTS Alamo Oct. 6,

Ti-scornia Dec. 5,

Arcand Feb. 26,

Plymale Mar. 7,

FOREIGN PATENTS Austria Apr. 11,

Images