Abstract:
A slider assembly configured to move on a slide rail along an axial direction without limitation in distance is provided to solve the problems of the middle retaining members of a conventional circulation maintaining device, e.g., insufficient connection rigidity and inconvenience in manufacture and assembly. The positioning portion of a middle retaining member and the positioning portion of the protrusion of a slider are connected in a direction perpendicular to both the axial direction and a transverse direction in which the protrusion projects, thereby connecting the middle retaining member and the protrusion securely and evenly along their entire lengths. The middle retaining member and the protrusion also feature ease of manufacture and assembly.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a slider assembly and more particularly to a slider assembly in which a protrusion is provided between two rail surfaces of a slider and in which the protrusion is connected with a middle retaining member in a direction perpendicular to an axial direction and to a transverse direction in which the protrusion projects so as to provide sufficient connecting strength and facilitate production and assembly. 
       BACKGROUND OF THE INVENTION 
       [0002]    When a slider assembly including a circulation maintaining device and a slider is mounted astride a slide rail, a plurality of closed circulation channels are formed jointly by the circulation maintaining device, the slider, and the slide rail. The circulation channels include a load channel formed between the slider and the slide rail, two turning channels respectively formed at two end surfaces of the slider, and return channels in the slider. Rows of rolling elements are received in the circulation channels and can roll in the circulation channels in a circulating manner without limitation in distance, thereby enabling the slider assembly to move smoothly along the slide rail. 
         [0003]    More specifically, the load channel in the circulation channels is formed jointly by retaining members provided by the circulation maintaining device, rail surfaces of the slider, and rail surfaces of the slide rail. The retaining members have generally the same length as the rail surfaces of the slider, are shaped as long, narrow pieces, and generally include upper retaining members, middle retaining members, and lower retaining members. The upper and lower retaining members, which are located above and below the rolling elements respectively, can be fixed or connected in their middle sections, from above and below respectively, for enhanced rigidity. The middle retaining members, however, which are located at half-height of the slide rail and therefore subject to limitation of space between the slide rail and the slider, are connected and secured at the end portions, as is typical of the conventional circulation maintaining devices (see U.S. Pat. No. 6,729,760 “Motion guide device” and US Patent Application Publication No. 20030035600A1 “Rolling element interference preventer and a guide device” for example). As the rolling elements tend to push one another and push against the retaining members while rolling in the load channel, it is likely that the rolling elements will fall out somewhere between the two ends of each middle retaining member, causing damage to the slider assembly. 
         [0004]    To increase the rigidity of a middle retaining member in its middle section, U.S. Pat. No. 7,204,036B2 “Linear guide apparatus” and U.S. Pat. No. 8,123,408B2 “Linear motion guide unit” disclose supporting, and thus enhancing the rigidity of, a middle retaining member by means of an elongated component made of a high-rigidity material such as steel. However, as the high-rigidity component can be fixed only at its two ends too, the improvement is limited, and this solution does not respond well to the trend of having increasingly longer slider rigid bodies. To overcome this shortcoming, U.S. Pat. No. 5,129,736 “Indefinite linear motion guide unit having four endless circulating paths” proposes passing a bolt transversely through each of the two solid feet of a slider from outside so as to fasten each middle retaining member to the slider at a position between two rail surfaces. However, not only is it difficult to make threaded through holes in the two feet of a solid rigid body, but also the number of components and the complexity of assembly will be increased. All of these contribute to a rise in production cost. 
       SUMMARY OF THE INVENTION 
       [0005]    In view of the above, the present invention puts forward a slider assembly which can adapt to the increasing lengths of slider rigid bodies, which allows the middle retaining members of a circulation maintaining device to be connected to a slider in such a way that sufficient connecting strength exists along the entire length of each middle retaining member, and which advantageously features easy manufacture and assembly without incurring additional costs. 
         [0006]    The slider assembly of the present invention is configured to move in a linear and reciprocating manner on a slide rail along an axial direction by means of circulating rolling movement of rows of rolling elements. 
         [0007]    The slider assembly includes a slider and a middle retaining member. The slider is provided with at least one foot. The foot has at least two rail surfaces and a protrusion between the two rail surfaces. The protrusion projects in a transverse direction, extends along the axial direction, and is provided with a first positioning portion. The middle retaining member extends along the axial direction and is provided with a second positioning portion. By connecting the second positioning portion with the first positioning portion, the middle retaining member is fixed to the protrusion. More specifically, the first positioning portion and the second positioning portion are connected along the axial direction and in a direction (hereinafter referred to as the connecting direction) perpendicular to both the axial direction and the transverse direction. Preferably, the middle retaining member and the protrusion are connected along their entire lengths in the axial direction. 
         [0008]    In one embodiment of the present invention, there are a plurality of first positioning portions arranged at intervals along the axial direction and a plurality of second positioning portions arranged at intervals along the axial direction. If the middle retaining member is equally divided along the axial direction into two end portions and a middle portion between the two end portions, it is preferable that the two end portions and the middle portion are at least each provided with one second positioning portion. 
         [0009]    In one embodiment of the present invention, the middle retaining member is provided with a groove along the axial direction. The groove, to be mounted on the protrusion of the slider, has an inner surface including two opposite lateral surfaces configured to connect with the protrusion in a precise manner. The inner surface of the groove further includes a bottom surface connecting the two opposite lateral surfaces. In addition, the first positioning portion is a positioning hole extending through the protrusion in a direction perpendicular to both the axial direction and the transverse direction. The positioning hole can be made by a processing process carried out directly from below the slider without being interfered by other components. The second positioning portion, on the other hand, is a positioning block. The positioning block is aligned with the first positioning portion, is located on either of the two opposite lateral surfaces of the groove, and extends toward the bottom surface of the groove. When there are a plurality of such positioning blocks located on the two opposite lateral surfaces of the groove, the positioning blocks on one of the two opposite lateral surfaces of the groove may correspond to the positioning blocks on the other of the two opposite lateral surfaces respectively along the axial direction. Or, the positioning blocks on one of the two opposite lateral surfaces of the groove may be alternately arranged with respect to the positioning blocks on the other of the two opposite lateral surfaces along the axial direction. 
         [0010]    In one embodiment of the present invention, the middle retaining member is made of an elastic material such as plastic or metal, the second positioning portion is a positioning block which increases in size toward the bottom surface of the groove, and the middle retaining member is mounted on the protrusion along the opposite direction of the transverse direction. 
         [0011]    In one embodiment of the present invention, the positioning block of the middle retaining member has an end portion which is adjacent to the bottom surface of the groove and provided with a recess, making it easier for the positioning block to engage in the positioning hole of the protrusion. 
         [0012]    In one embodiment of the present invention, both the first positioning portion and the second positioning portion are through holes, and a pin is inserted through the through holes to connect the middle retaining member and the protrusion. Preferably, the middle retaining member is provided with a groove along the axial direction, the groove of the middle retaining member is mounted on the protrusion of the slider, the groove has an inner surface including two opposite lateral surfaces, and the pin extends through the two opposite lateral surfaces to connect the middle retaining member and the protrusion. 
         [0013]    In one embodiment of the present invention, the middle retaining member has two retaining surfaces for retaining rolling elements, and each of the retaining surfaces has a guide groove for guiding a retaining chain. 
         [0014]    The present invention has the following advantageous effects:
   1. The first positioning portion of the protrusion—be it a positioning hole for engaging with a positioning block or a through hole through which a pin can extend—can be manufactured directly from below the slider without interference by other components, thus featuring easy manufacture and assembly and low production cost.   2. Once the middle retaining member and the protrusion of the slider are connected by connection of the first and second positioning portions in the connecting direction, the middle retaining member and the protrusion are restricted to the same extent anywhere along their entire lengths in the axial direction. As a result, the connecting strength of the middle retaining member and the protrusion is enhanced, allowing the two parts to withstand greater stress as a whole. Further, as the middle retaining member is effectively prevented from sliding and deformation, the smoothness of motion of the rolling elements will be increased.   3. Since the middle retaining member of the present invention is made of an elastic material, the groove of the middle retaining member can be forced open to facilitate the engagement of the positioning block in the groove and the positioning hole in the protrusion of the slider, thereby increasing the convenience of installation of the middle retaining member.   
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The invention as well as a preferred mode of use and the advantages thereof will be best understood by referring to the following detailed description of some illustrative embodiments in conjunction with the accompanying drawings, in which: 
           [0019]      FIG. 1  is a perspective view of the middle retaining member in the first embodiment of the present invention; 
           [0020]      FIG. 2  is a side view of the middle retaining member shown in  FIG. 1 ; 
           [0021]      FIG. 3  is a perspective view showing how the middle retaining member and the slider in the first embodiment of the present invention are put together; 
           [0022]      FIG. 4  is an assembled perspective view of the middle retaining member and the slider in the first embodiment of the present invention; 
           [0023]      FIG. 5  is a partially sectional view of the slider in the first embodiment of the present invention, in which the right-hand side of the drawing schematically shows a middle retaining member connected to a protrusion, while the left-hand side of the drawing schematically shows the configuration of a positioning hole in the opposite protrusion, to which no middle retaining member is connected; 
           [0024]      FIG. 6  schematically shows an assembly step of the first embodiment of the present invention, in which a groove of the middle retaining member is forced open so that the positioning blocks in the groove can easily engage in the positioning holes in the protrusion of the slider; 
           [0025]      FIG. 7  schematically shows how the positioning blocks in the groove of the middle retaining member are engaged in the positioning holes in the protrusion of the slider in the first embodiment of the present invention; 
           [0026]      FIG. 8  schematically shows how the slider in the first embodiment of the present invention is further connected with an upper retaining member and a lower retaining member, sits astride a slide rail, and has rolling elements put in place; 
           [0027]      FIG. 9  schematically shows the recess provided in each positioning block in the groove of the middle retaining member in the second embodiment of the present invention, wherein the recesses enable deformation of the positioning blocks so that the positioning blocks can engage in the positioning holes in the protrusion of the slider; 
           [0028]      FIG. 10  schematically shows how the positioning blocks in the groove of the middle retaining member in the second embodiment of the present invention are engaged in the positioning holes in the protrusion of the slider; 
           [0029]      FIG. 11  schematically shows how the positioning blocks in the third embodiment of the present invention are alternately arranged in the groove of the middle retaining member along the axial direction; and 
           [0030]      FIG. 12  schematically shows how the middle retaining member is connected to the protrusion of the slider by a pin in the fourth embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The technical features and major effects of the slider assembly of the present invention will be clearly shown via the following embodiments. 
         [0032]    The slider assembly of the present invention can move on a slide rail E along an axial direction S in a linear and reciprocating manner thanks to the circulating rolling movement of rows of rolling elements R, as explained in more detail below with reference to the drawings, particularly  FIG. 8 , in which the direction perpendicular to the page is defined as the axial direction S. 
         [0033]    Referring to  FIG. 1  and  FIG. 2  for the first embodiment of the present invention, a middle retaining member  1  extends along the axial direction S and is provided with a groove  11  along the axial direction S. The groove  11  has an opening  111 . The inner surface of the groove  11  includes two opposite lateral surfaces  112  and  113  and a bottom surface  114  connecting the two lateral surfaces  112  and  113 . A plurality of positioning blocks  12  are evenly arranged on each of the two lateral surfaces  112  and  113 , wherein the positioning blocks  12  on the lateral surface  112  correspond in position to the positioning blocks  12  on the lateral surface  113  respectively. The middle retaining member  1  is made of an elastic material such as plastic or metal. The positioning blocks  12  on the two lateral surfaces  112  and  113  increase in size toward the bottom surface  114 . The middle retaining member  1  is further provided with two retaining surfaces  13  for retaining the rolling elements R. Each of the two retaining surfaces  13  has a guide groove  131  for guiding a retaining chain Z (see  FIG. 8 ). 
         [0034]    Referring to  FIG. 3 ,  FIG. 4 , and  FIG. 5 , the middle retaining member  1  is installed on a slider  2 . The slider  2  has an inverted square U-shaped cross-section with two feet  21 . A mounting portion  22  is formed between the two feet  21  so that the slider  2  can sit astride the slide rail E. The two feet  21  each has an inner side that is provided with two rail surfaces  211  and  212 . Between each pair of the rail surfaces  211  and  212  is a protrusion  23  which projects in a transverse direction Y, extends along the axial direction S, and is formed with a plurality of positioning holes  231  evenly arranged along the axial direction S and corresponding to the positioning blocks  12  of the middle retaining member  1 . The positioning holes  231  penetrate the protrusions  23  in a direction defined as a connecting direction C, which is perpendicular to both the axial direction S and the transverse direction Y. The positioning holes  231  can be made from below the slider  2  without interference by any other parts and therefore feature ease of production. 
         [0035]    Reference is now made to  FIG. 6  and  FIG. 7 . To install the middle retaining member  1  to the slider  2 , an external force F is applied to open the opening  111  of the groove  11  of the middle retaining member  1 , and then a pushing force P is applied to fit the groove  11  of the middle retaining member  1  onto the protrusion  23  of the slider  2 , thus bringing the positioning blocks  12  to the positioning holes  231 . After that, the middle retaining member  1  is released, allowing the positioning blocks  12  to engage in the positioning holes  231  completely, and thereby fixing the middle retaining member  1  to the protrusion  23 . The connection between the positioning blocks  12  and the positioning holes  231  in the connecting direction C is advantageous in that not only is the manufacturing process made easy, as mentioned above, but also production cost can be lowered due to the reduced number of components and ease of assembly. It should be pointed out that, referring again to  FIG. 1 , the correspondingly connected positioning holes  231  and positioning blocks  12  in this embodiment are evenly arranged in the axial direction S along the protrusion  23  of the slider  2  and the middle retaining member  1  respectively. If the middle retaining member  1  in this embodiment is equally divided along the axial direction S into two end portions  14  and a middle portion  15  between the two end portions  14 , the positioning blocks  12  are evenly distributed in each of the two end portions  14  and the middle portion  15 . In  FIG. 1 , the middle retaining member  1  has a length L, and the positioning blocks  12  are provided on the middle retaining member  1  at a fixed interval D and are therefore evenly distributed in the end portions  14  and the middle portion  15 . As such, connection between the middle retaining member  1  and the protrusion  23  takes place along their entire lengths, and all the connected positions are equally restrictive. The strength of connection between the middle retaining member  1  and the protrusion  23  is therefore increased, allowing the two components to withstand greater stress in the connected state. 
         [0036]    Referring to  FIG. 8 , the assembly process of the slider assembly of the present invention further includes connecting an upper retaining member  3  and a lower retaining member  4  to the slider  2  and placing rows of rolling elements R in place, wherein each row of the rolling elements R is retained in the retaining chain Z. The two ends of the slider  2  are then covered with end caps respectively. (The end caps, which are not shown in the drawing, are well known in the art and therefore will not be described in detail herein.) Once the slider assembly is fitted astride the slide rail E, a linear guide rail is completed and ready to be used. In order for the rolling elements R to drive the slider assembly along the slide rail E, referring to the right-hand side of  FIG. 8 , an upper load channel and a lower load channel are formed jointly by the retaining surfaces  13  of the middle retaining member  1 , the rail surfaces  211  and  212  of the slider  2 , retaining surfaces  31  and  41  respectively provided by the upper retaining member  3  and the lower retaining member  4 , and rail surfaces E 1  and E 2  provided by the slide rail E. The retaining chains Z are guided by the guide grooves  131  of the middle retaining member  1  and guide grooves  311  and  411  respectively provided by the retaining surfaces  31  and  41  of the upper retaining member  3  and the lower retaining member  4 . 
         [0037]      FIG. 9  and  FIG. 10  show the second embodiment of the present invention. In this embodiment, the middle retaining member  5  has generally the same configuration as the middle retaining member  1  in the first embodiment. The differences between the two embodiments are shown in the drawings and detailed as follows. The middle retaining member  5  has a groove  51  whose inner surface is provided with a plurality of evenly arranged and corresponding positioning blocks  52 . Each of the positioning blocks  52  of the middle retaining member  5  is provided with a recess  53 . When it is desired to install the middle retaining member  5  to the protrusion  23  of the slider  2 , there is no need to apply the force F (see  FIG. 6 ) for opening the groove  51 ; only the pushing force P is required to press the positioning blocks  52  against the protrusion  23 . This is because the positioning blocks  52  can readily engage in the positioning holes  231  of the protrusion  23  through elastic deformation and restoration caused by the pushing force P and enabled by the recesses  53 , which provide the positioning blocks  52  with room for deformation. 
         [0038]    The third embodiment of the present invention is shown in  FIG. 11 , in which the middle retaining member  6  has generally the same configuration as the middle retaining member  1  in the first embodiment except that the positioning blocks  62  in the groove  61  of the middle retaining member  6  are alternately arranged. This embodiment has the same effects as the first embodiment. 
         [0039]      FIG. 12  shows the fourth embodiment of the present invention and more particularly a middle retaining member  7  and a slider  8 . The middle retaining member  7  extends along the aforesaid axial direction S. (The extending of the middle retaining member  7  can be readily known from the previous embodiments and therefore is not shown in  FIG. 12 .) The middle retaining member  7  has a groove  71  whose inner surface includes two opposite lateral surfaces  711  and  712 . In addition, the middle retaining member  7  has a plurality of through holes  72  extending through the two lateral surfaces  711  and  712 . The through holes  72  are distributed in the same manner as the positioning blocks  12  in the first embodiment. Like the slider  2  in the first embodiment, the slider  8  has two opposite protrusions  81 . Each protrusion  81  has a plurality of through holes  811  corresponding respectively to the through holes  72 . To assemble, the groove  71  of the middle retaining member  7  is mounted on the corresponding protrusion  81  of the slider  8 , before a pin  9  is inserted through each pair of the corresponding through hole  72  and through hole  811  to connect the middle retaining member  7  and the protrusion  81 . This embodiment can achieve the same effects as the first embodiment. 
         [0040]    While the operation, use, and effects of the present invention have been fully disclosed through the foregoing embodiments, it is understood that the embodiments are not intended to restrict the scope of the present invention, which encompasses all simple, equivalent changes and modifications based on the claims and specification of the present invention.