Bellows
FIELD OF THE INVENTION 
     The present invention relates to an accordion type bellows, including an flexible member which is formed by bending a sheet of flexible material in zig-zag fashion. 
     BACKGROUND OF THE INVENTION 
     A typical example of a conventional accordion type bellows is shown in FIGS. 1 and 2. 
     FIG. 1 is an enlarged drawing of a part of the bellows shown in FIG. 2. The conventional bellows, as shown in FIG. 3, includes flexible members 3, each of which is formed so as to be flexible by bending a sheet member such as a cloth or a plastic sheet in a zig-zag fashion. Both ends of the cloth or sheet are fixed to opposing mounting plates 2 and reinforcement wires 4 are provided with the sheet member wound around them. 
     In the conventional bellows 1, when an external force is applied to the flexible member 3 from a direction as shown by the arrow A, the reinforcement wires 4 are bent backward and the flexible member 3 is irregularly bent. In order to overcome that drawback of the conventional bellows in FIG. 3, there has been proposed a bellows having plastic plates 5 attached to planar portions of the flexible member 3, as shown in FIG. 4. The plastic plates 5, however, cause the thickness of the bellows to be greatly increased when it is collapsed. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved bellows which is not easily deformed by an external force applied thereto. 
     Another object of the present invention is a bellows which has a small thickness when collapsed. 
     A further object of the present invention is a bellows which is capable of long-lasting use. 
     These and other objects of the present invention are accomplished by a bellows comprising a pleated bellows body collapsible and extendable along a predetermined bellows axis and including an interior, an exterior, and a plurality of sides, and a reinforcement member attached to the bellows body, the reinforcement member having a plurality of edges attached to the interior of corresponding sides of the bellows body at the location of a pleat thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the sidewall of a conventional bellows; 
     FIG. 2 is another perspective view of a conventional bellows; 
     FIG. 3 is a cross-sectional view of FIGS. 1 and 2 taken along the line III--III in each and showing one sidewall of the conventional bellows; 
     FIG. 4 is a cross-sectional view of another embodiment of a conventional bellows; 
     FIG. 5 is a cross-sectional view of the sidewall of one embodiment of the bellows of the present invention; 
     FIG. 6 is a cross-sectional view of the sidewall of another embodiment of the present invention; and 
     FIG. 7 is a perspective view of a frame element used in the embodiments of FIGS. 5 and 6. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 5 and 6 show embodiments of the present invention, wherein like reference numerals designate like components in FIGS. 1 to 4. 
     FIG. 5 shows a side view of one sidewall, also termed a &#34;side&#34; or &#34;side member&#34;, of one embodiment of the bellows of the present invention, wherein both ends of a flexible member 3, e.g., a cloth sheet, are attached to opposing mounting plates 2. Flexible member 3 is formed into a series of pleats 12 series-connected along bellows axis 14 and having outwardly (with respect to bellows axis 14) converging creases 16 and inwardly converging creases 18. Reinforcement plates 7 are provided in the sidewalls of the bellows. The reinforcement plates 7 are constructed in a window frame fashion and each is formed by a rectangular frame 71 of thin steel plate with sides 71a-71d. Each side 71a-71d has a holding cloth 72 wound around it. 
     One side or edge of the holding cloth 72 wound around the side 71a of the rectangular frame 71 is stitched together with the bent portion, i.e., a crease, of the flexible member 3. The holding cloths 72 covering the other three sides 71b-71d of the reinforcement plate 7 are also stitched to bent portions or creases of the other three flexible members of the sidewalls of the bellows. A plurality of the reinforcement plates 7 are fixedly mounted to the flexible members 3 at intervals along the expansion and contraction axis of the bellows, namely along bellows axis 14. In the embodiment shown in FIG. 5, two reinforcement plates 7 are provided along the lengths of the flexible member 3 such that they divide the longitudinal length of the flexible member into three equal parts. 
     In a bellows constructed in this manner, even if an external force is applied in the direction shown by the arrow A in FIG. 5, the external force is absorbed by the rigid reinforcement plates 7 to prevent the deformation of the flexible member 3. Further, the thickness of the fully collapsed bellows along the expansion/contraction axis thereof is not as large as the one shown in FIG. 3 because only a small number of reinforcement plates 7 need be mounted to the flexible members 3 in order to provide adequate reinforcement. 
     FIG. 6 is a sideview showing a part of an elastic member used in another embodiment of the present invention which differs from the embodiment of FIG. 5 in that the reinforcement plate 7 is formed by winding the side 71a of the rectangular frame 71 not by a holding cloth but by the cloth sheet constituting the flexible members 3. The function and advantages of this embodiment are substantially the same as the embodiment of FIG. 5. 
     While the salient features of the present invention have been described with reference to the drawings, it should be understood that the preferred embodiments described herein are susceptible of modifications and alterations without departing from the spirit and scope of the following claims.