Abstract:
An air barrier that prevents entrainment of surrounding air from the welding environment into the welding helmet is provided. The barrier for the welding helmet contains a flexible curtain, front and rear edges, and means for securing the front edge of the curtain adjacent to the rear edge of the helmet. The flexible curtain may be made of fire-resistant and flexible molded material. The air barrier may be permanently secured to or removable from the welding helmet. The invention may be used in conjunction with a variety of ventilation and cooling systems, including small units that mount on or in welding helmets, as well as more elaborate blowing systems partially carried by the welder.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Non-provisional patent application of U.S. Provisional Patent Application No. 61/031,415, entitled “Helmet Cooling and Air-Filtering System”, filed Feb. 26, 2008, which is herein incorporated by reference. 
     BACKGROUND 
     The invention relates generally to welding helmets, and more particularly to arrangements for controlling the influx of air into a welding helmet. 
     Welding can be a heat intensive process, especially during the summer months in outdoor locations or in plants without air conditioning or good air circulation. Furthermore, welding environments contribute fumes and particulates to the locations in which welding is performed. While some industrial standards exist that require powered air purifying respirator (PAPR) systems, such standards may not apply to all situations in which improved air circulation may be desirable for operator comfort, particularly over extended periods of work. Moreover, when not required, PAPR systems represent a relatively costly approach to ventilation and cooling. 
     Certain relatively lower cost, lightweight airflow systems have been proposed that can be mounted to the welding helmet, and that offer a promising solution to this problem. However, these systems are often less than satisfactory, in particular due to the potential for entrainment of surrounding air from the welding environment into the welding helmet. Therefore, there exists a need for improvements in such systems that prohibit outside air from degrading the air quality in the helmet. 
     BRIEF DESCRIPTION 
     The present invention provides methods and devices designed to respond to such needs. The invention may be used in conjunction with a variety of ventilation and cooling systems, including small units that mount on or in welding helmets, as well as more elaborate blowing systems partially carried by the welder. The invention provides an air barrier for a welding helmet that prevents or reduces the intrusion of surrounding air into the helmet from the welding environment. The barrier for the welding helmet contains a flexible curtain, front and rear edges, and means for securing the front edge of the curtain adjacent to the rear edge of the helmet. These means may include, inter alia, elastic bands, hook and loop fastener arrangements, and so forth. Certain embodiments may include minor alterations, such as apertures, designed to outfit the barrier for use with multiple airflow systems of various design. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a side view of a welder wearing a welding helmet with an air barrier and an airflow system in accordance with aspects of the present invention; 
         FIG. 2  is a front view of the barrier of  FIG. 1 , removed from the welding helmet of  FIG. 1 ; 
         FIG. 3  is a cross sectional view of the barrier of  FIG. 2  illustrating elastic cords in hems on either edge to facilitate placement of the barrier in use; 
         FIG. 4  is a front view of the barrier of  FIG. 1  illustrating the use of a hook and loop fastener system for attachment to the welding helmet; 
         FIG. 5  is a side view of a welder wearing a welding helmet with an air barrier of  FIG. 1  and a clip-on exterior ventilation unit; 
         FIG. 6  is a front view of the barrier of  FIG. 5  illustrating an aperture in the barrier to accommodate an air flow conduit of the clip-on unit; 
         FIG. 7  is a side view of a welder wearing a welding helmet with an air barrier of  FIG. 1  and an internal ventilation unit; 
         FIG. 8  is a side view of a welder wearing a welding helmet attached to an external ventilation system; 
         FIG. 9  is a side view of a welder wearing a welding helmet with an air barrier and the ventilation system of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a welding helmet  10  that is worn on the head  12  of a welder. The welding helmet  10  may be attached to a shield  14 , which covers the face of the welder during welding. The shield  14  contains a visor  16  with an embedded dark or autodarkening lens  18  through which the welder can view the welding process. The area between the shield  14  and the head of the welder  12  is a volume  20  where air can flow. In the various embodiments of the invention described below, a forced air system is provided that blows fresh filtered air across the face of the welder within the inner volume  20 . An air barrier  22  in the form of a flexible curtain prevents the entrainment of surrounding air from the welding environment. As described below, the barrier  22  may be removable from the helmet  10 , and may be designed as an add-on item that a welder can affix to the helmet for use with a ventilation system to prevent unfiltered outside air from being drawn into the inner volume of the helmet. 
     The front edge  24  of the barrier  22  can be formed either on or in the curtain  30  and urges the flexible curtain towards the welding helmet  10 . In certain embodiments, the front edge  24  may be elastic. As illustrated, when the curtain is in place on the helmet, the rear edge  26  of the helmet is disposed immediately adjacent to the front edge  24  of the curtain  30 . The rear edge  28  of the curtain  30  extends out above the head of the welder  12 . This curtain  30  may be constructed of fire resistant, flexible material, such as a 200 denier nylon with 1.5 ounce per square yard urethane coating that meets an industry standard fire test for flame propagation specification NFPA 701-89, although other materials may be used. The elastic front edge  24  includes a hem  32  with an elastic band disposed in it. In the illustrated embodiment, the elastic band terminates on either side with loops or hooks that can be wrapped around helmet head gear features, such as adjustment knobs  40  on either side of the helmet. Furthermore, this elastic edge  24  urges the flexible curtain  30  towards the helmet, preferably just forward of the rear edge thereof. Loops  36  serve to secure the entire structure to the helmet, yet allow it to be very easily removed when desired. This hook and loop system allows for the barrier  22 , secured to the head of the welder  12 , to prevent air flow  42  from the welding environment from entering the volume  20  inside the helmet  10  of the welder. 
       FIG. 2  illustrates the curtain  30  detached from the headgear with the aforementioned loops  34 . As mentioned above, the loops  34  (or other attachment structures), allow the curtain to be removably secured to an adjustment knob on either side of the head of the welder  12 . Other attachment mechanisms may be envisaged, and where desired the curtain may form a permanent part of the helmet or headgear assembly. In the illustrated embodiment, the first hem  32  and the second hem  36  meet at the corners  44  of the curtain  30 , where the elastic loops  34  extend outward on either side.  FIG. 3  is a cross sectional view along line  3 - 3  of  FIG. 2 . As can be seen in this view, the barrier  22  is comprised of the curtain  30  extending between the first hem  32  and the second hem  36 . The hems may be formed by rolling the fabric of the curtain and stitching to form an elongated opening. Each hem contains a respective elastic cord, as illustrated, including a first elastic cord  46  and a second elastic cord  48 , which extend out to form the loops that secure the curtain  30  to the helmet. 
     Other attachment arrangements for securing the curtain  30  to or near the rear edge of the helmet may include hook and loop fasteners, glue, rivets, snaps, buttons, and so forth. For example, as shown in  FIG. 4 , hook/loop fastener arrangements may include strips or tabs  50  made of either a hook or a loop component of such a system, with the complementary component (loop or hook) being secured to the helmet (not shown). As will be recognized by those skilled in the art, some welding helmets will not be conducive to retaining an air barrier by elastic biasing towards the helmet alone. As a further alternative to the securement arrangements discussed above, one or more clips may be used that would firmly grasp or capture a portion of the helmet, such as adjacent to the rear edge. 
     It should also be noted that the air barrier may terminate at various locations between the rear edge of the helmet and the head gear used to retain the helmet on the head of the welder. That is, as will be appreciated by those skilled in the art, such welding helmets generally include a band that surrounds the welder&#39;s head, the size of which may typically be adjusted by slides or a knob located along the rear of the band (see, e.g.,  FIG. 1 ). The rear of the air barrier may terminate in the vicinity of this head gear band, and may be secured to the band, where desired. Alternatively, as described above, the barrier may terminate at a location between the head gear and the rear edge of the helmet. In both cases, the barrier is considerably shorter and cooler than covers used with existing systems, such as conventional PAPR ventilating systems. 
     The air barrier  22  may be adapted for use with multiple types of airflow systems that circulate air into and through the inner volume  20  between the head of the welder  12  and the welding helmet  10 .  FIG. 5  illustrates an airflow system in which a clip-on unit  52  is added as an auxiliary system to the welding helmet  10 , and that draws in outside air and blows the air through the volume  20  to cool the welder. Because such systems will typically include one or more conduits that extend from the unit into the inner volume  20 , accommodation may be made in the air barrier for such conduits. In this embodiment, the barrier  22 , illustrated in  FIG. 6 , includes an aperture  54  to facilitate passage of such a conduit. The conduit may simply be positioned through the aperture when the clip-on unit and barrier are mounted to the helmet. The flexible material around the aperture provide a sufficient seal to reduce or eliminate the inflow of air into the helmet through the opening 
     The air barrier  22  can also be used with a similar system as shown in  FIG. 7 . In this embodiment, the helmet has been fitted with an interior blower unit  56  that draws in outside air, such as through one or more holes or openings formed in the shell of the helmet. The air may be directed to flow through the volume  20  to cool the welder, while the barrier, as before, prevents drawing unfiltered air through the opening between the helmet and the head of the welder. 
     The air barrier  22  can also be used to exclude outside air from contaminating the ventilation system  58  shown in  FIG. 8 . The system shown in  FIG. 8  includes a battery/blower unit  60  that draws outside air through a filter  62  from the back of the welder, which is typically cleaner than environmental air closer to the welding location. The battery/blower unit  62  may, as in the illustrated embodiment, be worn by the welder, such as on the welder&#39;s belt, or a dedicated belt. The unit is connected to a conduit  64 , which feeds filtered air into the welding helmet  10 .  FIG. 9  is a somewhat more detailed view of such a system when outfitted with the air barrier  22 . As in the previous embodiments, the front edge  24  of the barrier  22  fits snuggly to the rear edge of the welding helmet  10 , while the rear edge  28  is biased towards the back of the head of the welder  12 . 
     It should be noted that, depending upon the material used to form the air barrier, the barrier may collapse or bunch when the helmet is moved to a raised position, as generally shown in  FIG. 8 . This may generally be the case for various fabrics, and the foregoing arrangements illustrated in the other figures may perform similarly. It is believed that such barriers will prove to be lighter, cooler and more comfortable to wear. Alternatively, however, the air barrier may be made of a semi-rigid material that generally retains its shape and form when the helmet is moved. Still further, certain designs presently contemplated may include a number of louvers, interleaving elements, telescoping elements, or accordion-like elements that collapse when the helmet is raised, and that expand or move with respect to one another when the helmet is lowered to a working position. 
     While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.