Abstract:
A corrugated tube has a slit ( 13 ) and first closing walls ( 14 A) of circumferentially extending annular projections ( 12 ) are formed along the slit ( 13 ). Lock projections ( 16 ) dimensioned to be fitted inside the annular projections ( 12 ) are provided between the first closing walls ( 14 A) and second closing walls ( 15 A). The lock projections ( 16 ) are tapered toward the projecting ends thereof and clearances, into which the first closing walls ( 14 A) are insertable are defined between the lock projections ( 16 ) and the second closing walls ( 15 A). Out of the opposite ends ( 14, 15 ) of the annular projections ( 12 ), the ends corresponding to the first closing walls ( 14 A) are fitted on the lock projections ( 16 ) to engage the first closing walls ( 14 A) and the lock projections ( 16 ), thereby locking the slit ( 13 ) in a closed state.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a corrugated tube provided with a locking structure. 
         [0003]    2. Description of the Related Art 
         [0004]    A corrugated tube formed with a longitudinal slit is known conventionally for mounting on a specified position of a wire group. This corrugated tube can be fit sideways on the specified position of the wire group by opening the slit. However, the slit of the corrugated tube is opened when the wire group is bent. Therefore taping or the like needs to be applied. 
         [0005]    U.S. Pat. No. 6,078,009 relates to a corrugated tube with a locking structure for locking the slit in a closed state so that taping is unnecessary This corrugated tube is constructed to lock the slit by forming mutually engageable locking recesses at the opposite ends of the annular projections (opposite ends facing at the opposite sides of the slit) and engaging these locking recesses. 
         [0006]    However, the above construction has a problem when using the corrugated tube with a mounting member, such as a protector, thereon because the mounting member easily gets caught by the locking recesses of the annular projections if an attempt is made to rotate the mounting member in a circumferential direction of the corrugated tube. 
         [0007]    The present invention was developed in view of the above situation and an object thereof is to preventing a mounting member from getting caught in a circumferential direction even if having a locking structure. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention relates to a corrugated tube with circumferentially extending projections at specified intervals in a longitudinal direction and a slit formed substantially in the longitudinal direction. Opposite ends of projections at opposite sides of the slit are closed substantially by closing walls. A first of the substantially opposite closing walls is formed substantially along the slit. One or more lock projections are provided between the first closing walls and the second closing walls and are dimensioned to fit at least partly inside the projections. Clearances are defined between the lock projections and the second closing walls for receiving the first closing wall. The first closing walls and the lock projections are engaged to lock the slit in a closed state when ends near the first closing walls are fit on or to the lock projections. The outer shape of the corrugated tube with the slit locked is approximate to that of a normal corrugated tube. Accordingly, the corrugated tube will not get caught by a mounting member in a circumferential direction even though the locking structure is provided. 
         [0009]    The lock projections preferably are tapered towards the projecting ends thereof. Thus, the corrugated tube can be produced by a blow molding method similar to the normal corrugated tube. 
         [0010]    Guide surfaces are formed on the lock projections facing the slit and are inclined to increase a projecting distance gradually towards the second closing walls of the annular projections. Thus, the first closing walls are guided by the guiding surfaces of the lock projections to pass the lock projections over merely by closing the slit. Therefore the ends of the annular projections need not be lifted up and a locking operation can be performed easily. 
         [0011]    Ribs may be formed between the lock projections and the second closing walls to increases the rigidity of parts between the second closing walls and the lock projections and to prevent the lock projections from being inclined. Therefore, the slit can be held locked with an increased force. 
         [0012]    The ribs may be provided at positions substantially corresponding to the widthwise centers of the lock projections. 
         [0013]    The lock projections may be provided in a one-to-one correspondence with all of the preferably annular projections. Thus, the slit reliably is held closed. 
         [0014]    The ribs may be provided in a one-to-one correspondence with all of the lock projections. Thus, the inclination of all of the lock projections is prevented and the slit is held closed with even a larger force. 
         [0015]    The lock projections may have a substantially trapezoidal shape when viewed in directions along the circumferential and longitudinal directions of the corrugated tube. 
         [0016]    The corrugated tube may be produced by blow molding or vacuum molding. 
         [0017]    These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments. 
     
    
     
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
         [0018]      FIG. 1  is a side view partly in section showing a corrugated tube of one embodiment. 
           [0019]      FIG. 2  is a section along A-A of  FIG. 1 . 
           [0020]      FIG. 3  is a section along B-B of  FIG. 1 . 
           [0021]      FIG. 4  is a section showing a state before a slit is locked in a closed state. 
           [0022]      FIG. 5  is a side view showing a state where the slit is locked closed. 
           [0023]      FIG. 6  is a section showing the state where the slit is locked closed. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    A corrugated tube in accordance with the invention is identified by the numeral  10  in  FIGS. 1 to 10 . The corrugate tube  10  is to be mounted on a specified position on an unillustrated wire group for substantially surrounding and protecting the wire group. The corrugated tube  10  is made e.g. of synthetic resin and has a bellows or wave-like shape with annular projections  12  that project at specified intervals from a substantially cylindrical inner wall  11 . Additionally, the corrugate tube  10  has sufficient flexibility to follow a layout path of the wire group. A substantially straight slit  13  is formed over the entire length of the corrugate tube  10  longitudinal direction. 
         [0025]    Each annular projection  12  has a first end  14  at the slit  13  and a second end  15  spaced from the slit  13 . The first and second ends  14  and  15  of each annular projection  12  substantially face one another at the opposite sides of the slit  13 . 
         [0026]    Each annular projection  12  has a projecting end surface  12 A that is substantially parallel to the inner wall  11  of the corrugated tube  10  and opposite side surfaces  12 B that converge towards the projecting end surface  12 A. Thus, each annular projection narrows towards the projecting end surface  12 A and the distance between adjacent annular projections increases at positions closer to the projecting end surfaces  12 A. The respective annular projections  12  have substantially isosceles trapezoidal cross sections when viewed in a direction along the circumferential direction of the corrugated tube  10 . 
         [0027]    The first and second ends  14  and  15  of each annular projection  12  are closed respectively by first and second closing walls  14 A and  15 A. The first and second closing walls  14 A,  15 A have substantially trapezoidal shapes and close the ends of the annular projection  12  by having peripheral edges continuous with the side surfaces  12 B of the annular projection  12 , the projecting end surface  12 A of the annular projection  12  and the inner wall  11 . The first closing walls  14 A are formed along the slit  13  so that the slit  13  extends substantially straight in the longitudinal direction along the first closing walls  14 A. 
         [0028]    Lock projections  16  project from the inner wall  11  at positions between the second closing walls  15 A and the slit  13  and between the first and second closing walls  14 A,  15 A at positions aligned with the annular projections  12 . One lock projection  16  is provided for each annular projection  12  and is at a position slightly distanced from the slit  13  towards the corresponding closing wall  15 A (see  FIG. 1 ). 
         [0029]    Each lock projection  16  has a projecting end surface  16 A that is substantially parallel to the inner wall  11  and opposite side surfaces  16 B that converge towards the projecting end surface  16 A. Thus, the spacing between the side surfaces  16 B on adjacent lock projections  16  increases at positions closer to the projecting end surfaces  16 A (see  FIG. 2 ). A guiding surface  16 C is formed on each lock projection  16  facing the slit  13  and is inclined to gradually increase a distance to the second closing wall  15 A, as shown in  FIG. 4 . A locking surface  16 D is formed on a portion of each lock projection  16  facing the second closing wall  15 A and is aligned substantially perpendicular to the inner wall  11  of the corrugated tube  10 . The locking surface  16 D and the second closing wall  15 A are substantially parallel, and a clearance of two or more times the thickness of the first closing wall  14 A is defined therebetween. An insertion portion  17  is defined between the locking surface  16 D and the second closing wall  15 A for receiving the first closing wall  14 A. 
         [0030]    All of the lock projections  16  have a substantially trapezoidal shape when viewed in directions along the circumferential and longitudinal directions of the corrugated tube  10 . The respective lock projections  16  are dimensioned to fit closely into the corresponding annular projections  12 . More specifically, with the respective lock projections  16  fit in the first ends  14  of the corresponding annular projections  12 , the substantially opposite side surfaces  16 B of the lock projections  16  have substantially the same inclinations as the opposite side surfaces  12 B of the annular projections  12  and are arranged proximate to these side surfaces  12 B. 
         [0031]    Ribs  18  are formed on the inner wall  11  of the corrugated tube  10  between the locking surfaces  16 D of the locking projections  16  and the second closing walls  15 A. The ribs  18  are provided in a one-to-one correspondence with the locking projections  16  and are arranged at positions corresponding to the widthwise centers of the respective locking projections  16  along the longitudinal direction of the corrugated tube  10  and project unitarily from the inner wall  11  while spanning between the locking surfaces  16 D and the second closing walls  15 A. In this way, parts of the inner wall  11  between the locking projections  16  and the second closing walls  15 A where the ribs  18  are provided have a larger wall thickness in inward and outward directions due to the thickness of the ribs  18  as compared with other parts. 
         [0032]    The slit  13  of the corrugated tube  10  is opened and the corrugated tube  10  is fit sideways or substantially radially on the wire group or any other element to be protected. The first closing walls  14 A are guided by the respective inclined guiding surfaces  16 C of the locking projections  16  and move onto the projecting end surfaces  16 A as the slit  13  is closed. The first closing walls  14 A pass the projecting end surfaces  16 A of the locking projections  16  as the slit  13  is closed further and enter into the inserting portions  17 . The inserting portions  17  are slightly larger than the thickness of the first closing walls  14 A. Thus, the first closing walls  14 A enter the inserting portions  17  in inclined postures. 
         [0033]    The locking surfaces  16 D of the locking projections  16  face the first closing walls  14 A when first closing walls  14 A are inserted into the inserting portions  17  to lock the slit  13  in a closed state. More particularly, the first ends  14  of the annular projections  12  are fit on the locking projections  16  and only tiny clearances are left between the first closing walls  14 A in the inserting portions  17  and the second closing walls  15 A. Therefore the annular projections  12  are substantially continuous without any projections or recesses over the entire circumference. In other words, with the slit  13  locked in the closed state, the projecting end surfaces  12 A and side surfaces  12 B of the annular projections  12  of the corrugated tube  10  and the inner wall  11  have smooth substantially cylindrical shapes free from projections and recesses over substantially the entire circumference, and the corrugated tube  10  approximates the outer shape of a normal corrugated tube (i.e. a slit-free corrugated tube or a corrugated tube having no locking structure even if formed with a slit) (see  FIGS. 5 and 6 ). Accordingly, a mounting member, such as a protector, can be mounted on the corrugated tube  10  and can be rotated smoothly without getting caught by the mounting member in the circumferential direction. 
         [0034]    The lock projections  16  are tapered toward their projecting ends. Thus, the corrugated tube  10  can be produced by a blow molding method similar to the conventional corrugate tube. 
         [0035]    The first closing walls  14 A are guided by the guiding surfaces  16 C of the lock projections  16  to move over the lock projections  16  while locking the slit  13  in the closed state. Thus, the first ends  14  need not be lifted up to fit on the lock projections  16  so that the locking operation can be performed easily. 
         [0036]    The lock projections  16  are provided for all of the annular projections  12  and the slit  13  is locked at all of the annular projections  12 . Thus, the slit  13  is held reliably closed over substantially the entire length of the corrugated tube  10 . 
         [0037]    The opposite side surfaces  16 B of the lock projections  16  are substantially parallel to the opposite side surfaces  12 B of the annular projections  12  when the first ends  14  fit on the lock projections  16 . Thus, the side surfaces  16 B of the lock projections  16  the contact side surfaces  12 B of the annular projections  12  to prevent relative displacements of the respective lock projections  16  and first ends  14  in the longitudinal direction if the corrugated tube  10  is bent. Therefore, relative displacements of the opposite ends  14 ,  15  of the annular projections  12  in the longitudinal direction are restricted and the annular projections  12  are kept substantially continuous in the circumferential direction. 
         [0038]    The ribs  18  between the lock projections  16  and the second closed walls  15  increase rigidity so that these parts are difficult to bend even upon the action of contact forces of the lock projections  16  and the first closing walls  14 A. Specifically, the ribs  18  provide rigidity against bending deformation in a direction that would displace the lock projections  16  inwardly of the corrugated tube  10  and prevent the lock projections  16  from being inclined. Accordingly, the lock projections  16  and the first closing walls  14 A are unlikely to disengage from each other even if relatively large forces act on the lock projections  16  while bending the corrugated tube  10 . Hence, the slit  13  remains closed. Further, the ribs  18  are at positions substantially corresponding to the widthwise centers of the lock projections  16 . Thus, the ribs  18  provide well balanced resistance to bending deformations that could incline the lock projections  16 . The ribs  18  are provided for all of the lock projections  16 . Thus, the inclination of all of the lock projections  16  are prevented and the slit  13  is held closed with an increased force. 
         [0039]    As described above, the outer shape of the corrugated tube  10  in the locked state of the slit  13  is approximate to the outer shape of a normal corrugated tube. Thus, the corrugated tube  10  will not get caught by a mounting member in the circumferential direction despite the existence of the locking structure. 
         [0040]    The invention is not limited to the above described embodiment. For example, the following embodiments also are embraced by the scope of the invention as defined by the claims. 
         [0041]    Although the invention is applied to the corrugated tube  10  having the slit  13  formed over the entire length in the above embodiment, it is also applicable to a corrugated tube having a slit partly formed. Moreover, the corrugate tube may have a cross-sectional shape different from a substantially circular one such as a polygonal, squared, rectangular, elliptical or the like shape. 
         [0042]    Although the lock projections  16  are substantially trapezoidal when viewed in both the circumferential direction and the longitudinal direction in the above embodiment, the lock projections may have any shape provided that they are dimensioned to be fit inside the annular projections and are tapered towards the projecting ends. For example, the lock projections may have a triangular pyramidal shape. Moreover, the projections of the corrugated tube need not to be annular, but may have different shapes such as a substantially spiral shape so that one end of one projection may oppose an end of another projection. 
         [0043]    The inserting portions  17  are slightly larger than the wall thickness of the first closing walls  14 A in the above embodiment, but they may not be larger. 
         [0044]    Surfaces of the lock projections  16  facing the slits  13  are inclined in the above embodiment, but these surfaces may not necessarily be inclined surfaces. 
         [0045]    The ribs  18  are formed between the lock projections  16  and the second closing walls  15 A in the above embodiment. However, they may not be formed. 
         [0046]    The ribs  18  are at the widthwise centers of the lock projections  16  in the above embodiment. However, they may be displaced from the center positions. 
         [0047]    The lock projections  16  are provided for all the annular projections  12  in the above embodiment. However, the lock projections may be provided for fewer than all annular projections, e.g. every other annular projection. 
         [0048]    The ribs  18  are provided for all the lock projections  16  in the above embodiment. However, ribs may be provided only for some lock projections. 
         [0049]    The corrugated tube  10  is produced by the blow molding in the above embodiment, but it may be produced by other methods (e.g. vacuum molding).