Abstract:
The present invention relates to a length-expandable linear guideway, which main includes a slide way that can change the distance. The main characteristic of it is the slideway of the linear guideway has the function of the expanded and contracted. Thereby this model can cut down the install space of the linear guideway, and can enlarge the application scope of the linear guideway.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a length-expandable linear guideway, which main includes a slide way that can change the distance. The main characteristic of it is the slideway of the linear guideway has the function of the expanded and contracted. Thereby this model can cut down the install space of the linear guideway, and can enlarge the application scope of the linear guideway.  
           [0003]    2. Description of the Prior Arts  
           [0004]    A conventional linear guideway as shown in FIG. 6, which includes a fixed guide track  50  disposed on a datum level, also includes a object (not shown) disposed on the sliding block  40 , the sliding block  40  is slidably mounted on the fixed guide track  50  so that the object to be born is permitted to linearly move along the fixed guide track  50 . The maximum travel of the linear track is exactly same as the movable distance of the sliding block  40  on the fixed guide track  50 , which equals, the length L of the fixed guide track  50  minus that N of the sliding block  40 , thereby, the longer the moving distance is, the longer of the rail length L to be required. Vice versa, in case that the required moving distance is fixed, the longer the length N of the sliding block  40  is, the longer the rail length L to be required. However, the length of the fixed guide track  50  is normally fixed, so the longer the length of the fixed guide track  50  is, the larger installation space should be required. Nowadays, the linear guideway has been commonly applied in precision and normal machinery, so the install space of the linear guideway demands to be saved; otherwise the application scope of it will be restricted.  
           [0005]    The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional linear guideway.  
         SUMMARY OF THE INVENTION  
         [0006]    Due to the linear guideway has been applied to the general mechanical transmissions in a wide range, such as feeder of a manufactory, automatic-doors used in all kinds of surroundings (train, shop, public places and so on), however, the stall space is one of the common problems of them should be overcome.  
           [0007]    The length-expandable linear guideway of the present invention changes the guideway structure from length-fixed structure into a length-expandable one which having a function of expanded and contracted. By utilizing the theory of tandem and telescopic, the slideway of the present invention is designed as a structure that can change the distance, viz. the slideway of the present invention can expand to a maximum extent based on the tandem structure, while the same can be contracted to a minimum extent based on the telescopic design. Thereby the linear guideway of the present invention has a function of contracted and expanded such that can cut down the stall space of it and expand the distance of the linear slideway to a moderate degree as needed.  
           [0008]    The linear guideway of the present invention has been changed from the conventional type of consisting of a length-fixed guideway structure for fitting into the bearing rail (carriage) into a length-expandable guideway for fitting the bearing rail (carriage), which including a fixed and a slidable portion. Thus, the linear guideway structure of the present invention, in a telescopic manner without adding extra spaces, is able to expand the length of it sector by sector by virtue of a tandem manner. In other words, which can be tandem linked in different sectors as needed to extend the length. By such an arrangement, the maximum extent of the expandable linear guideway of the present invention can be achieved and expanded without extra spaces being required, thus the install space of such the expandable linear guideway of the present invention is relatively cut down and overcome the problem of install space. Furthermore, which can expand the length to a moderate extent so as to enlarge the application scope of the linear guideway as well as improve the competitive power of the same.  
           [0009]    The primary objective of the present invention is to provide an expandable linear guideway of one-way directional or bi-directional expandable for purpose of saving space of installation.  
           [0010]    The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which shows, for purpose of illustrations only, the preferred embodiments in accordance with the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is an exploded view of a length-expandable linear guideway in accordance with a first embodiment of the present invention;  
         [0012]    [0012]FIG. 2 is a perspective view of the length-expandable linear guideway in accordance with the first embodiment of the present invention, showing an expanded status;  
         [0013]    [0013]FIG. 3 is a perspective view corresponding to FIG. 2 of showing a contracted status of the length-expandable linear guideway of the present invention;  
         [0014]    [0014]FIG. 4 is a perspective view of the length-expandable linear guideway in accordance with a second embodiment of the present invention, showing an expanded status;  
         [0015]    [0015]FIG. 5 is an exploded view of the length-expandable linear guideway in accordance with the present invention;  
         [0016]    [0016]FIG. 6 is a plan view of a conventional length-expandable linear guideway. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    [0017]FIG. 1 is an exploded view of a length-expandable guideway in accordance with a first embodiment of the present invention, wherein a length-expandable linear guideway of the present invention consists of a base guide track  10 , a U-shaped guide track  20  and a slide base  30 . The base guide track  10  includes a plurality of apertures  11  formed at the bottom so as to be fixed on a datum level by virtue of the apertures, and includes two ball grooves  12  formed at both inner lateral sides respectively, the two ball grooves  12  corresponding to two ball grooves  21  are formed at both outer lateral sides of the U-shaped guide track  20  respectively. Two connecting members  13  are respectively disposed between the ball grooves  12 , 21  for confining the slide of the balls  16  therebetween. A cover plate  14  and stop plate  15  are disposed at both ends of the base guide track  10  respectively for preventing the connecting members  13  sliding out therefrom, such that the slide of the connecting members  13  are confined within the base guide track  10 . Similarly, two ball grooves  22  are formed at both inner lateral sides of the U-shaped guide track  20  respectively, the two ball grooves  22  are corresponding to two ball grooves  31  formed at both outer lateral sides of the slide base  30 . Two connecting members  23  are disposed between the ball grooves  22  and  31  for confining the balls  26  and sliding therebetween. A cover plate  24  and a stop plate  25  are disposed at both ends of the U-shaped guide track  20  respectively for preventing the connecting members  23  sliding out therefrom, such that the slide of the connecting members  23  is confined within the U-shaped guide track  20 . Therefore, the U-shaped guide track  20  is movable relative to the base guide track  10  and the slide base  30  respectively, and the object is fixed in the fixed holes  32  of the slide base  30  and permitted to move along the U-shaped guide track  20 .  
         [0018]    Referring to FIGS. 2-3, FIG. 2 is a perspective view of the length-expandable linear guideway in accordance with the first embodiment of the present invention, showing an expanded status. FIG. 3 is a perspective view corresponding to FIG. 2 of showing a contracted status of the length-expandable linear guideway of the present invention. The U-shaped guide track  20  is movable within the base guide track  10  and the slide base  30  is also movable within the U-shaped guide track  20 , thereby the guiding travel of the length-expandable linear guideway in accordance with the present invention equals the moving travel of the U-shaped guide track  20  within the base guide track  10  plus that of the slide base  30  within the U-shaped guide track  20 , viz. the moving travel of the expandable linear guideway of the present invention is two times longer comparing with the original one. When the U-shaped guide track  20  moves back into the base guide track  10  and so does the slide base  30  move back into the U-shaped guide track  20  simultaneously, so that the base guide track  10 , U-shaped guide track  20  and slide base  30  may be superposed one another. Thereby, the length of the length-expandable linear guideway in accordance with the present invention is shortened. That is to say, the install space is saved. On the other hand, in order to allow the slide base  30  and the U-shaped guide track  20  to expand from the U-shaped guide track  20  and the base guide track  10  respectively, the stop plates  15 , 25  are open-slot formed respectively at an end of the base guide track  10  and the U-shaped guide track  20  so that the slide base  30  and the U-shaped guide track  20  are permitted to expand from the end of the U-shaped guide track  20  and the base guide track  10  respectively where the stop plates  25 , 15  are correspondingly disposed and the moving travel of the length-expandable linear guideway is lengthened.  
         [0019]    [0019]FIG. 4 is a perspective view of the length-expandable linear guideway in accordance with a second embodiment of the present invention, showing an expanded status. In which, the length-expandable linear guideway of the present invention is permitted to expand bi-directionally. Thereby both ends of the U-shaped guide track  20  and the base guide track  10  are provided with an open-slot shaped stop plates  25  and  15  so that the slide base  30  and the U-shaped guide track  20  are permitted to extend from both ends of the U-shaped guide track  20  and the base guide track  10  respectively where the stop plates  25 ,  15  are correspondingly disposed, such that the moving travel of the length-expandable linear guideway is lengthened.  
         [0020]    Referring further to FIG. 5, which shows another limiting device on the moving travel of the length-expandable linear guideway for purpose of preventing the slide base  30  and the U-shaped guide track  20  from sliding out therefrom. Wherein a locating slot  17  is formed at the bottom of the base guide track  10 , and alike, a plurality of locating apertures  27  are formed at the bottom of the U-shaped guide track  20 , a locating bolt  28  is engaged with one of the locating apertures  27  at a predetermined position then the moving travel of the U-shaped guide track  20  can be restricted by the cooperation between the locating bolt  28  and the locating apertures  27 . The expanding direction of the length-expandable linear guideway can be changed by the change of the locating bolt&#39;s  28  engaging position with the locating apertures  27 . In case that the locating bolt  28  on the U-shaped guide track  20  engages with the locating aperture  27  on the left, the U-shaped guide track  20  is permitted to expand out from the right end of the base guide track  10 . The U-shaped guide track  20  is permitted to expand out from both ends of the base guide track  10  in case that the locating bolt  28  engages with the locating aperture  27  in the middle. The rest is deduced by this analogy. And alike, this limiting device on the moving travel is also applicable to the slide base  30  so as to restrict the moving travel of it by cooperating with the U-shaped guide track  20 .  
         [0021]    It should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.