Beds – Sleeping bag – Including inflatable portion or attachment
Reexamination Certificate
2000-04-04
2001-04-17
Grosz, Alexander (Department: 3628)
Beds
Sleeping bag
Including inflatable portion or attachment
C002S069500, C112S475080
Reexamination Certificate
active
06216290
ABSTRACT:
BACKGROUND OF THE INVENTION
Since the first patents issued for sleeping bags in the 1930's, many improvements in sleeping bag design have been developed. Today, sleeping bags are made of extremely lightweight materials and provide substantially improved thermal insulation. In order to maximize the bag's thermal insulation capacity, mummy shaped bags have been developed to reduce the volume of air inside the bag, which enhances thermal efficiency because the user's body heat will be able to more efficiently warm a smaller volume of air. Another important improvement in sleeping bag design has been the development of the draft tube. A draft tube is a longitudinal insulation filled tube, which is attached to the inner lining of a sleeping bag and adjacent to the access zipper which is normally located on the side of the sleeping bag. The function of the draft tube is to overlay the inside surface of the zipper when the zipper is closed, so as to partially block the flow of warm air from the inside of the sleeping bag out through the zipper. The primary problem associated with mummy style sleeping bags is that while they are warmer than wider bags, they are relatively confining and uncomfortable. Wide bags, while more comfortable in warmer conditions, are by nature not as warm when the temperature drops such that the user may be uncomfortably cold. As a result, there is a need for a sleeping bag which essentially retains the thermal insulating benefits of a mummy style sleeping bag and draft tube, but is also comfortable and less confining during more moderate temperatures. The present invention satisfies that need.
SUMMARY OF THE INVENTION
The present invention recognizes that the general design and location of prior art draft tubes provide an ideal combination for realizing the goal of increasing the comfort of a mummy style sleeping bag when it is used during moderate temperatures, and without any loss of thermal efficiency when it is used during more severe conditions. The design of prior art draft tubes is used, with a new and unique modification, to provide the additional fabric needed to expand the sleeping bag, and the draft tube's location is utilized to ensure that the expanded bag is comfortable.
In prior art sleeping bags the draft tube is made from an elongated and generally rectangular shaped piece of fabric, having two opposite longitudinal draft tube edges. In general, as shown in
FIG. 1
, the fabric is used to form a draft tube by sewing one draft tube edge to the sleeping bag's inner lining, and the other draft tube edge is sewn to the fabric strip of an access zipper, which are in turn sewn to the longitudinal edges of the sleeping bag's inner lining and outer shell. Thermal insulation is placed inside the draft tube and its two ends are sewn closed. The draft tube extends a predetermined distance into the inner portion of the sleeping bag so that it overlays the access zipper.
The present invention modifies the prior art draft tube design by incorporating two additional features into the draft tube and sleeping bag, which are utilized when the draft tube is attached to the inner lining and outer shell of the sleeping bag. One feature is an elongated expansion zipper and the other is an elongated expansion segment. One of the draft tube's longitudinal edges is attached in the usual manner to the sleeping bag's inner lining, but after the other longitudinal draft tube edge is attached to the access zipper's fabric strip, those two components are not then sewn to the longitudinal edges of the sleeping bag's inner lining and outer shell edges. Rather, the other longitudinal draft tube edge and its associated access zipper's fabric strip are also sewn to the longitudinal edge of the expansion segment and the fabric strip of the expansion zipper. Next, the other longitudinal edge of the expansion segment and the other access zipper's fabric strip are sewn together, which are also sewn to the longitudinal edges of the sleeping bag's inner lining and outer shell. Before thermal insulation is placed inside the modified draft tube, one of its two ends are sewn closed, and after filling the draft tube with insulation material, the other end is sewn closed. Further, as in the prior art design, the modified draft tube extends a predetermined distance into the inner portion of the sleeping bag so that it overlays the access zipper. When the expansion zipper is unzipped, the circumferential dimension of the sleeping bag's inner lining and outer shell both increase the same proportional amount. Although the distance that the modified draft tube extends across the access zipper is reduced when the sleeping bag is expanded, the draft tube still overlays the access zipper, because the distance the modified draft tube extends across the access zipper when the sleeping bag is not expanded, is increased a predetermined amount, which is proportional to the increase in the sleeping bag's circumference when it is expanded. Thus, the present invention's modified draft tube continues to provide the important insulating function of a prior art draft tube, and the additional function of permitting the sleeping bag's user to expand the bag without adding any significant modification to the bag's inner lining, which would otherwise make the sleeping bag less comfortable.
REFERENCES:
patent: 4090269 (1978-05-01), Hunt
patent: 5386602 (1995-02-01), Krenzler
patent: 5490294 (1996-02-01), Kramer
Scott Phillip Bayerd
Zemitis Martin Steven
Grosz Alexander
Hendrickson Jay P.
Mountain Hardwear, Inc.
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