Back Frame

This invention relates generally to life support breathing systems and the like, and more particularly, to a back frame therefor operable to support compressed breathing air tanks of various sizes. The back frame of the present invention provides a structure which is relatively simple to operate but which provides a high degree of safety and flexibility in use with respect to a predetermined range of various air tank sizes.

When a person must subsist in an atmosphere which is toxic, oxygen deficient or which for some other reason cannot support human life, he is equipped with a life support system comprising, for example, a breathing mask supplied with breathing air from a regulated source. His exhalation usually is exhausted to the ambient atmosphere. In particular, it is contemplated that the present invention be utilized by firefighters who are continually exposed to the aforesaid types of conditions.

Annually the number of materials which give off toxic products of combustion increases which in turn increases the hazards faced by firefighters. Accordingly, it is well recognized that firefighting is one of the most hazardous occupations in the United States. Even though the prior art provides apparatus for protection against such hazards however, it has been found that the level of respiratory injuries has been continuously rising.

Current breathing apparatus offers a level of protection from such hazards, but because such apparatus is heavy, bulky, and hard to don and wear, it is often not fully utilized by the working firefighter. It has been found that the discomfort and loss of mobility occasioned by firefighters using prior art apparatus is more significant than the protection which it provides in marginally dangerous situations.

In particular, a shortcoming of the prior art is to be found in not providing a lightweight, easy to operate and dependable back frame for supporting compressed breathing air tanks of varying diameters as are usually utilized in the life support systems considered herein. It is highly desirable that such air tanks, having limited supplies, may be quickly and securely exchanged when a life support system is in continuous, extended use. Necessarily, it is further desirable that these features exist for air tanks of different sizes all of which may be employed with the life support system.

Accordingly, one object of the present invention is to provide a new and improved back frame for supporting a tank of compressed breathing air in a life support system wherein the tank or a replacement therefor may be quickly mounted on the back frame with a high degree of assurance that the tank will remain in place during use.

Another object of the present invention is to provide the aforesaid improved back frame having a "fail-proof" latch for ensuring retention of a tank on the frame.

A further object of the present invention is to provide the aforesaid back frame with a retaining strap which is adjustable in regard to the degree of retention force applied to an air tank and in regard to its nominal length with respect to air tanks of different nominal sizes.

Still another object of the present invention is to provide the aforesaid improved back frame which is of lightweight and compact construction so as to minimize the discomfort and fatigue experienced by a user while maximizing his manueverability and efficiency, particularly with respect to firefighting applications.

In summary, the present invention provides a back frame for supporting a tank of compressed breathing air wherein the frame includes a pair of lateral edge rails spaced from the back of a user at the top portion thereof and being inclined so as to extend toward the back of the user at the bottom portion thereof. A retaining strap is mounted at each of its ends on the upper respective portions of the guide rails. The end connections of the retaining strap are slidable along the edge rails to vary the retention force applied to an air tank mounted thereunderneath, such variation in retention force resulting from the inclined nature of the edge rails. The retaining strap includes a one of its ends a stepped or multiple link connecting bracket whereby the effective length of the strap can be adjusted to accommodate tanks of various diameters. Furthermore, the other end of the strap includes a toggle latch for loosening and tightening the strap with respect to an air tank mounted on the frame. Accordingly, the relatively nominal and fine retention force adjustments provided respectively by the stepped bracket and inclined edge rails assures the firm engagement of an air tank against the frame while the toggle latch associated with the strap provides for ready exchange of the air tank. A U-shaped vertical support bracket is provided near the bottom of the back frame for vertical engagement with an apertured collar on the support tank.

The foregoing and other objects, advantages, and characterizing features of the present invention will become clearly apparent from the ensuing detailed description of an illustrative embodiment thereof, taken together with the accompanying drawings wherein like reference characters denote like parts throughout the various views.

FIG. 1 is a pictorial illustration representing a life support breathing system as utilized by a firefighter;

FIG. 2 is a front elevation view of the back frame of the present invention as seen when looking toward the back of a user;

FIG. 3 is a view similar to FIG. 2 showing a harness arrangement attached to the back frame for purposes of securing the same to the back of a user;

FIG. 4 is a side elevational view of the back frame as including a retaining strap at the upper portion thereof for retaining an air tank in a mounted disposition against the frame;

FIG. 5 is a transverse view partly in section through a neck portion of the air tank as taken about on line 5--5 of FIG. 4;

FIG. 6 is a view similar to FIG. 4 illustrating the opposite side of the assembly shown in FIG. 4;

FIG. 7 is an isolated, detailed view in fragmentary form of the stepped bracket connection of the retaining strap to one of the lateral edge rails of the back frame;

FIG. 8 is a transverse view partly in section of the air tank and retaining strap subassembly as taken about on line 8--8 of FIG. 6;

FIG. 9 is a view similar to FIG. 8 showing a transverse view in section of the air tank as taken about on line 9--9 of FIG. 6; and

FIG. 10 is an isolated view partly in section of the toggle latching means forming part of the retaining strap as taken about on line 10--10 of FIG. 4.

Referring now in detail to the illustrative embodiment depicted in the accompanying drawings, there is shown in FIG. 1 a life support breathing system as used in firefighting applications utilizing the back frame of the present invention for supporting a tank 20 of compressed breathing air. Air is supplied to a demand regulator 22 via a section of flexible hose 24 which passes beneath the user's left arm. The regulator 22 is connected to a face mask 26. The face mask or face piece 26 is a modified cone-shaped configuration made of a polycarbonate material with a rubber face seal for example. As stated, the present invention is related generally to the back frame 28 for supportably mounting air tank 20 and the pressure regulators associated therewith on a user's back.

Turning now to a consideration of FIG. 2, the back frame 28 includes upstanding metallic rail members 30 which are positioned adjacent to a user's back as are the crossover elements 32 and 34 which interconnect the upper portions of rails 30. The lower portions of rails 30 are connected by a U-shaped rail element 36 which extends outwardly from the plane of rails 30 as seen most clearly in FIGS. 4 and 6. In addition, a pair of inclined rails 38 form lateral edges of the body portion of frame 28. The inclined rails 38 as best viewed in FIGS. 4 and 6 are spaced from a user's back at their upper ends and extend or incline toward a user's back at their lower ends. An interconnecting rail element 40 is provided at the upper ends of rails 38 and is formed to curve outwardly from a user's back so as to receive tank 20 in a cradled manner.

A back plate 42 is shown in FIG. 2 for example has also interconnecting rails 30. Plate 42 is relatively flat so as to comfortably fit against a user's back and includes a turned edge 42a which provides for the mounting of hose end 24. The lower ends of rails 38 are in turn interconnected by a large U-shaped element 44 which as most clearly seen in FIGS. 2 through 4 provides for the attachment of the lower portion of the harness associated with the back frame. In a similar manner, the crossover bracket 34 provides for connection of the upper portion of the harness to the back frame. The back frame as including the lateral edge rails 38 and rails 30 is of an integral construction by the rigid engagement of correspondingly adjacent rails 30 and 38 together at the joints indicated as 46.

A retaining strap 48 is provided at the upper portions of rails 38. One end of the retaining strap is connected to a rail 38 by a stepped bracket 50. As viewed in FIGS. 6 and 7, the end of retaining strap 48, preferably being of a fire resistant material such as metal, includes a U-shaped end 48a for engagement over either of the steps or cross links 50a. As is to be further appreciated from a consideration of FIG. 8, the portion of bracket 50 connected to rail 38 includes apertured eye hook type configurations 50b which are received over rail 38 in a slidable manner.

The other end of retaining strap 48 is conncted to an edge rail 38 by toggle latching means 52. As best seen in FIGS. 4 and 8, the toggle is connected to strap 48 by the pinned U-shaped bracket 48a. As is apparent from the detailed illustration of FIG. 10, the wire bracket 52a forming part of the toggle may rotate with respect to its mounting in the strap bracket 48a. The other end of toggle element 52a is received within the pinned toggle clip element 52b. Clip 52b is of a closed loop construction as clearly shown in FIG. 10 and includes a pin 52c extending therethrough isolating the sliding connection of clip 52b on edge rail 38 at its left hand end as viewed in FIG. 10 from the sliding fit of toggle element 52a in the right hand end of clip 52b. In addition, a flexible tab 52d is attached to clip 52b for facilitating the opening and closing of the toggle.

Turning now to a consideration of the lower end of the back frame as seen in FIGS. 4 through 6, a vertical support bracket generally indicated as 54 is mounted on the crossover rail 36. The vertical support bracket 54 is provided to engage the apertured collar 56 affixed to the neck of tank 20. The support bracket 54 includes a crossover plate 54a which spans and is attached to crossover rail 36. An upwardly oriented, U-shaped bracket 54b depends from bracket 54a and is received through aperture 56a in the collar 56. In this manner, the collar 56 and necessarily tank 20 are vertically supported. In addition, bracket 54 includes a cantilevered leaf spring 54c which depends downwardly from bracket element 54a. The leaf spring as viewed in FIG. 4 is biased to the left to engage the adjacent side of the free end of the U-shaped bracket portion 54b. In this manner, the apertured collar 56 is vertically locked on the bracket portion 54b by the vertical restriction provided by the biased spring 54c. However, the extreme lower end of spring 54c is provided with a tab portion 54d which may be urged to the right in FIG. 4 for purposes of releasing the tank and associated collar 56 when for example the tank is to be replaced or exchanged.

In utilizing the apparatus forming and associated with the present invention, reference is made to FIGS. 4, 6 and 8 for example. Upon initially installing a tank 20 on the back frame, the toggle would be opened by revolving the same in a clockwise direction as viewed in FIG. 8 by grasping the toggle tab 52d -- as shown in FIG. 8 the toggle is closed. Thereafter, the top of the tank would be slid underneath strap 48 and raised vertically therethrough until the tank collar 56 was at a point above the U-shaped support bracket 54b. The tank would then be lowered so that aperture 56a would drop downwardly against leaf spring 54c to urge the latter to the right as viewed in FIG. 4 with the collar 56 bottoming out in bracket 54b. Necessarily, the biasing of spring 54c would return it to the position shown in FIG. 4 after passage of the collar thereby.

In tightening strap 48, the end 48a thereof would be engaged over one of the connecting links or step elements 50a to adjust the effective length of the strap to an appropriate degree corresponding to the diameter of the tank used. It is contemplated for example that air tanks on the order of five to seven inches in diameter will be utilized. Since it is preferred that strap 48 be made of fire resistant material such as metal, the strap will in and of itself not include any significant degree of elasticity. However, the bracket 50 and toggle 52 can be slid along the incline of edge rails 38 to provide precise adjustment to the retention force which will be applied to tank 20 when the toggle is closed. In addition, the rail elements 38 inherently include a certain degree of resiliency so that when the toggle is urged into a closed position as shown in FIG. 8, the adjustements provided by bracket 50 and the positioning of bracket 50 and toggle 52 on rails 38 and the resiliency of rails 38 in and of themselves provide for a firm retention of tank 20 against the cradling crossover element 40 of the frame. With the tank collar 56 securily locked in place and vertically supported by bracket 54b, it is ensured that the tank will remain properly mounted. Even if the toggle 52 should be accidentally opened during use of the system, the tank collar 56 would not become disengaged from bracket 54b and the tank would still be maintained in a proper orientation on the back of the user, although obviously be subject to shifting due to the relaxed condition of strap 48 under such circumstances.

From the foregoing, it is apparent that the objects of the present invention have been fully accomplished. As a result of this invention, an improved back frame is provided whereby air tanks may be changed quickly and in a manner involving minimum operational risk. The back frame is so formed to accommodate various sizes of air tanks and is contoured so that the center of gravity for a firefighter's breathing system for example is near the user body's natural center of gravity. In addition, the weight of the frame is carried on the hips in the area of crossover rail 44 and the harness portion attached thereto which results in better balance of the load. Necessarily, the user may move over hazardous terrain more safely and with much less fatigue. Furthermore, one of the most important aspects of the present invention is the fact that during extended use, air tanks may be exchanged or replaced quickly and safely without the user having to take off the back frame unit. Necessarily this latter aspect is important with respect to a firefighter's efficiency.

Having thus described and illustrated a preferred embodiment of our invention, it will be understood that such description and illustration is by way of example only and that such modifications and changes as may suggest themselves to those skilled in the art are intended to fall within the scope of the present invention as limited only by the appended claims.