Frame work for soft-sided luggage
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to the frame work for soft-sided luggage. In particular, this invention relates to the frame work for soft-sided luggage that is soft and flexible for easy manufacturing and assembly, and is also light in weight and strong in resistance to structural distortion. More particularly, this invention relates to the frame work for soft-sided luggage with standardized structural component that allows constructions of luggage with different structural configurations. 
     2. Technical Background 
     The main body of conventional luggage is comprised of metal frame work paneled by polyvinyl chloride (PVC) plastic cloth or plywood plates paneled by polyvinyl chloride (PVC) plastic cloth. Edges of the luggage body are generally reinforced by steel wires, and rivets are required to secure the various components of the entire luggage body. Such a conventional luggage construction, although enjoys the advantages of being strong in resistance to structural distortion, however, metal frame work, the plywood planes, rivets and steel wires increase considerably the weight of the luggage. On the other hand, the complicated construction also renders the production cost relatively high and is difficult to be manufactured. 
     SUMMARY OF THE INVENTION 
     The object of the present invention, therefore, is to provide a frame work for soft-sided luggage that is light in weight and can provide strong structural strength against distortion. 
     It is another object of the present invention to provide a frame work for soft-sided luggage that is easy and inexpensive to be manufactured. 
     It is still another object of the present invention to provide a frame work for soft-sided luggage that is flexible in assembling and allows constructions of luggage in different configurations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The present invention, together with its features and advantages are described in the following paragraphs in accordance with preferred embodiments and the accompanied drawings, in which: 
     FIG. 1A is a perspective view of a U-shaped base structure in accordance with an embodiment of the present invention as viewed from inside the luggage; 
     FIG. 1B is a cross-sectional view taken along line I--I of FIG. 1A; 
     FIG. 1C is a cross-sectional view taken along line II--II of FIG. 1A; 
     FIG. 2 is a perspective view of the U-shaped base structure of FIG. 1A as viewed from outside the luggage; 
     FIG. 3A is a perspective view of a U-shaped upper structure as viewed from inside the luggage; 
     FIG. 3B is a cross-sectional view taken along line III--III of FIG. 3A; 
     FIG. 4 is a perspective view of the U-shaped upper structure of FIG. 3A as view from outside the luggage; 
     FIG. 5 a perspective view showing the engagement of the U-shaped base structure and the U-shaped upper structure; 
     FIG. 6 is a perspective view showing a luggage frame work obtained by engaging the U-shaped base structure with the U-shaped upper structure; 
     FIG. 7 is a perspective view showing the luggage frame work of the present invention combined with an exterior panel while the luggage is opened; 
     FIG. 8A is a perspective view showing the luggage frame work with disassembled U-shaped base structure and the metal frame; 
     FIG. 8B is a perspective view showing the luggage frame work obtained by assembling the U-shaped base structure and the metal frame; 
     FIG. 9 is a perspective view showing the luggage frame work with the disassembled U-shaped base structure, the U-shaped upper structure and metal frame; and 
     FIG. 10 is a perspective view showing the luggage frame work obtained by assembling the U-shaped base structure, the U-shaped upper structure and the metal frame. 
    
    
     DETAILED DESCRIPTION 
     The present invention is best exemplified by a wheeled luggage embodiment in accordance with the present invention that is capable of configurational conversion. 
     Please refer to FIGS. 1A and 1B. The U-shaped base structure 2 is provided with one reinforcing rib 4 on each of the two side edges of its interior surface, and one reinforcing band 5 between and parallel to these two reinforcing ribs 4. Each of the reinforcing ribs 4 and reinforcing band 5 has a convex surface protruding toward the luggage interior, and has arc-shaped cross section, and serves as the primary measure for strengthening the rigidity of U-shaped base structure 2. One wheel base 6 is provided on each of the reinforcing ribs 4 at one corner of the U-shaped base structure 2 for receiving a wheel for trailing the luggage. Engaging holes 7 are provided at both ends of the two reinforcing ribs 4 for engagement with engaging latch rods 9 provided on U-shaped upper structure 3. One connecting lock tab 8 protruding at the center of each end of the U-shaped base structure 2 is further provided for engagement with the engaging notches 10 provided on U-shaped upper structure 3, and each of the connecting lock tabs 8 may be optionally provided with a rivet hole for rivet-engagement with each of the engaging notches 10. Two guide grooves 13 extending parallel to each other and also parallel to the reinforcing ribs 4 are provided to form one guide band 14 in the inner surface of the U-shaped base structure 2 at both ends of the reinforcing band 5. 
     Please refer now to FIG. 2, in which the U-shaped base structure 2 of FIG. 1A is shown as seen from the outside. Small rib plates 4a and 5a are provided at the back of the convex surface of reinforcing ribs 4 and reinforcing band 5 respectively for reinforcing purpose and can increase the rigidity of the U-shaped base structure 2. 
     As can be seen in FIGS. 3A, 3B and 4, a U-shaped upper structure 3 is provided to cooperate with the U-shaped base structure 2 to comprise the luggage frame work 1. Similar to the U-shaped base structure 2, the U-shaped upper structure 3 is also provided with one reinforcing rib 4 on each of the two side edges of its interior surface, and each of the reinforcing ribs 4 has a convex surface protruding toward the luggage interior, and has arc-shaped cross section, and serves as the primary measure for strengthening the rigidity of U-shaped upper structure 3. Small rib plates 4a are also provided at the back of the convex surface of reinforcing ribs 4 for reinforcing purpose and can increase the rigidity of the U-shaped upper structure 3. Engaging latch rods 9 are provided at both ends of the two reinforcing ribs 4 of the U-shaped upper structure 3 for engagement with the engaging holes 7 provided on U-shaped base structure 2. One engaging notch 10 is provided at the center of each end of the U-shaped upper structure 3 for engagement with the connecting lock tabs 8 provided on U-shaped base structure 2, and each of the engaging notches 10 may be optionally provided with a rivet hole that is exactly aligned with each of the rivet holes of the connecting lock tabs 8 for rivet-engagement therewith. 
     As shown in FIGS. 5 and 6, when the U-shaped base structure 2 and U-shaped upper structure 3 are assembled and engaged to constitute the first embodiment of the luggage frame work 1, the engaging holes 7 and connecting lock tabs 8 of the U-shaped base structure 2 can match exactly with the engaging latch rods 9 and engaging notches 10 of the U-shaped upper structure 3, respectively. The assembled luggage frame work 1 can be further enclosed by the panel 11, as shown in FIG. 7, wherein the luggage is opened. 
     A second preferred embodiment of the luggage frame work 1&#39; comprising the U-shaped base structure 2 and the metal frame 12 is shown in FIGS. 8A and 8B. In comparison with the first embodiment of the luggage frame work 1, the luggage frame work 1&#39; employed a metal frame 12 instead of the U-shaped upper structure 3. The metal frame 12 is inserted into the guide bands 14 provided on the U-shaped base structure 2, and the two ends of metal frame 12 are received in the two ends of reinforcing band 5 of the U-shaped base structure 2 so as to form the luggage frame work 1&#39;. The luggage frame work 1&#39; is suitable for occasions when the rigidity requirement of the upper portion of a luggage is not severe, and/or the edges of the panel 11 need to be reinforced or supported by steel wires. 
     A third embodiment of the luggage frame work 1&#34; comprising the U-shaped base structure 2, the U-shaped upper structure 3 and the metal frame 12 is shown in FIGS. 9 and 10. The luggage frame work 1&#34; is formed by connecting and assembling the U-shaped base structure 2 and the U-shaped upper structure 3 as described in the first embodiment of the luggage frame work 1, and further connecting and assembling the U-shaped base structure 2 and the metal frame 12 as described in the second embodiment of the luggage frame work 1&#39; to obtain an even stronger luggage. Such a luggage frame work 1&#34; is especially suitable for large luggage designs. 
     The U-shaped base structure 2 and U-shaped upper structure 3 can be made from, for example, engineering plastic by injection molding. The reinforcing ribs 4, reinforcing band 5, small rib plates 4a and 5a and other components are all injection molded on the U-shaped base structure 2 and U-shaped upper structure 3 to obtain increased integral rigidity. 
     The frame works 1, 1&#39; and 1&#34; of the present invention can be made from standardized structural components as described above. The standardized components can be combined to form different frame works 1, 1&#39; and 1&#34; based on different requirements. Persons skilled in the art can make modifications to the disclosed content of the present invention, such as the number, location and shape of the reinforcing ribs, without departing the disclosed scope of the present invention.