Abstract:
A distortable rolling element retainer belt and a linear motion guide apparatus include a flat belt with holes defined therein and a separating portion is located between the adjacent holes. An upper spacer and a lower spacer are connected to each separating portion and a recess is defined between each separating portion and the upper spacer as well as between each separating portion and the lower spacer. The two recesses are located at different sides of the upper and the lower spacers so that the spacers on the rolling element retainer belt can be distorted to overcome the resistance from bending when the rolling elements traveling in a circulating passage which is not perpendicular to the surface of the rolling element retainer belt.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a distortable rolling element retainer belt and a linear motion guide apparatus composed of the rolling element retainer belt, and more particularly, to a retainer belt having multiple rolling elements separated between the separators and the retainer belt is distorted to overcome resistance when the rolling elements move in a circulating passage that is not perpendicular to the surface of the retainer. 
     BACKGROUND OF THE INVENTION 
     A conventional linear motion mechanism includes a motion member and an axial rail member, wherein each of the motion member and the rail member provides at least one rail and the two respective rails are located corresponding to each other. A series of rolling elements are movable between and in contact with the rails. The motion elements provide a return passage and two direction changing passages to each of the rails corresponding thereto. The direction changing passages are connected to the straight return passages, the entry of the rail and the exit of the rail to form the circulating passage so that the rolling elements enter the return passage via the direction changing passage and then enter the other rail via the return passage and the direction changing passage. The rolling elements are movable within the circulating passage, and the movable member is movable along the rails by the rolling elements. 
     In order to avoid from impact between the rolling elements, U.S. Pat. No. 5,927,858 discloses separators between the rolling elements. However, there is clearance between the separators and the rolling elements so that the separators tend to be tilted and shifted, such that the separators interfere with the circulating passage and affect the motion of the rolling elements. 
     U.S. Pat. No. 5,947,605 and U.S. Pat. No. 6,155,718 disclose a rolling element retainer belt which has two axial and thin strips and the separators are connected to the strips, and the rolling elements are located and retained between the separators. The belt is an elongate, flat and flexible, so that the belt can be deformed in the direction perpendicular to the plane composed of the two strips and the plane is named the plane of the belt. However, the belt has higher stiffness in the perpendicular direction so that resistance is generated when deformed in the perpendicular direction. Accordingly, the rolling element retainer belt is suitable for being operated on the plane that is perpendicular to the plane of the belt and suitable for being deformed on a two-dimension plane. When the circulating passage is not located on the plane, the belt has to deform toward the direction that is inclined to the belt, and has to overcome the resistance in the perpendicular direction. In other words, the belt has to overcome the resistance when deforming toward the perpendicular direction. Thus, the rolling element retainer belt cannot move smoothly. 
     Taiwan Patent No. 1273185 discloses a rolling element retainer belt which improves the inherent problems of the above-mentioned conventional rolling element retainer belt, and comprises multiple rolling elements and a belt which provides multiple holes in which the rolling elements are accommodated. The retainer belt includes multiple separators which separate the adjacent rolling elements. At least two thin and elongate resilient strips are connected to two ends of transverse resilient belts. The transverse resilient belts are connected to the separators at the mediate portions thereof. The transverse resilient belts are ensured to have the longest length and sufficient flexibility and can be deformed toward two opposite directions. The separators can be rotated and tilted in different directions relative to the transverse resilient belts. The rolling element retainer belt has sufficient degrees of freedom to change direction in the three-dimensional circulating passage so as to be smoothly operated with less resistance. 
     However, the two ends of the transverse resilient belts connected to the resilient strips, and the separators connected to the transverse resilient belts provide the retainer belt with higher degrees of freedom when deforming. However, because the connection area between the separators and the resilient belts are limited, the structural strength may not be sufficient when the retainer belt continuously turns. Furthermore, the clearance between the rolling elements and the resilient belts makes the rolling elements shift and the resilient belts cannot position the rolling elements. 
     The present invention intends to provide a rolling element retainer belt which has a mounting surface for mounting the rolling elements so that when the rolling element retainer belt turns continuously, the rolling elements are well positioned and the retainer belt deforms properly to overcome the resistance when the turning. 
     SUMMARY OF TILE INVENTION 
     The present invention relates to a rolling element retainer belt and comprises an elongate and flat belt and multiple separators. The retainer belt has multiple holes defined axially therein and separation portions are located between the holes. Each separator has an upper spacer and a lower spacer, and the upper and lower spacers are located on two sides of the separation portion. Two recesses are respectively defined between the upper spacer and the separation portion and between the lower spacer and the separation portion. The two respective recesses are located at different sides of the upper and the lower spacers. 
     Preferably, each hole defines an inner surface between the upper and lower spacers and located in a direction perpendicular to the belt. The upper and lower spacers each have a smooth surface adjacent to the hole. The smooth surfaces each partially have a rolling element mounting surface which is smoothly connected with the inner surface of the belt. The inner surface is connected with the rolling element mounting surface of the adjacent upper spacer or the adjacent lower spacer to form a top mounting surface or a lower mounting surface. The rolling element mounting surface has an opening and a part of the smooth surface extends from the opening in tangent direction and forms a curved surface. The direction of the opening of the top mounting surface/lower mounting surface is located at an angle between the vertical direction and the horizontal direction of the belt. The rolling element mounting surfaces of the upper spacer, lower spacer are located on opposite sides. The directions of the openings are opposite to each other. The recesses are located in the curved surfaces of the smooth surfaces. 
     Preferably, the rolling element mounting surfaces are spherical mounting surfaces or cylindrical mounting surfaces. 
     Preferably, the curved surfaces are cylindrical surfaces or cone-shaped surfaces. 
     The present invention relates to a linear motion guide apparatus and comprises a rail having a first passage in a side thereof and a block is mounted to the rail and has a second passage which is located corresponding to the first passage. Two direction changing passages are located on two ends of the second passage. The two direction changing passages are connected with a straight return passage. A circulating passage is formed by the second passage, the direction changing passages and the return passage. The circulating passage has at least one enclosed guide slot defined therein. The rolling element retainer belt has at least one of two sides thereof located in the guide slot. The rolling element retainer belt has holes defined therein and each hole has a rolling element received therein. The rolling element retainer belt moves along the circulating passage by moving the rolling elements within the circulating passage such that the rolling element retainer belt is ensured to move along the correct path. 
     The advantage of the present invention is that a notch is formed during the injection molding and located between the curved surface on the smooth surface of the upper spacer and the lower spacer and the separation portion so that when the rolling element retainer belt is moving in the circulating passage along the plane that is not perpendicular to the retainer belt surface, the upper and lower spacers are deformed to overcome the resistance. Besides, the structural strength between the upper and lower spacers and the separation portion is strong enough and the rolling element mounting surfaces retain the rolling elements in position. 
     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view to show the rolling element retainer belt of the present invention; 
         FIG. 2  is another perspective view to show the rolling element retainer belt and the rolling elements of the present invention; 
         FIG. 3  is a cross sectional view, taken along line A-A of  FIG. 1 ; 
         FIG. 4  is a cross sectional view, taken along line B-B of  FIG. 1 ; 
         FIG. 5  is a cross sectional view, taken along line C-C of  FIG. 1 ; 
         FIG. 6  shows that the rolling element retainer belt and the rolling elements of the present invention are located in the circulating passage of the linear motion guide apparatus; 
         FIG. 7  shows that the return passage is not located on the perpendicular plane T 1  of the guide plane H 1 , and 
         FIG. 8  shows that the rolling element retainer belt is deformed due to the resistance when moving in the direction changing passage. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , the rolling element retainer belt  1  of the present invention (the rolling element can be rolling cylinder) comprises an elongate and flat belt  2  and multiple separators  3 , wherein the belt  2  has multiple holes  21  defined axially therein and separation portions  22  are located between the holes  21 . Each separator  22  has a separator  3  mounted thereto and each separator  3  has an upper spacer  31  and a lower spacer  32 . The upper and lower spacers  31 ,  32  are located on two sides of the separation portion  22 . Each hole  21  defines an inner surface  35  between the upper and lower spacers  31 ,  32  and located in a direction perpendicular to the belt  2 . As shown in  FIG. 2 , multiple rolling members  5  are engaged with the holes  21  and separated by the separators  3 . When the linear motion guide apparatus moves along the circulating passage as shown in  FIG. 6 , the rolling elements  5  in the rolling element retainer belt  1  do not interfere with each other and move smoothly. 
     The upper and lower spacers  31 ,  32  each have a smooth surface  33 / 34  located adjacent to the hole  21  and a part of the smooth surface  33 / 34  is slightly larger than the spherical mounting surface  33   a / 34   a  of the rolling element  5 . If the rolling elements are rolling cylinders, the mounting surface is cylindrical mounting surface. The smooth surface  33 / 34  is smoothly connected to the inner surface  35  of the belt  2 , and the smooth surface  33 / 34  is connected with the spherical mounting surface  33   a / 34   a  of the adjacent upper spacer  31  or the adjacent lower spacer  32  via the inner surface  35  to form the top mounting surface  37  or the lower mounting surface  38 . As shown in  FIGS. 4 and 5 , the end that the top/lower mounting surface  37 / 38  does not connect to the inner surface  35  defines an opening  39  in the smooth surface  33 / 34 . The spherical mounting surfaces  33   a ,  34   a  are located on two opposite sides. The directions N 1 , N 2  of the openings  39  of the spherical mounting surfaces  33   a ,  34   a  are opposite to each other, and the directions N 1 , N 2  of the openings  39  of the spherical mounting surfaces  33   a ,  34   a  are located between the vertical direction “V” and the horizontal direction “H” of the cross section of the belt  2 , as shown in  FIG. 3 . 
     As shown in  FIGS. 4 and 5 , the diameter e 1 /e 2  of the opening of the spherical mounting surfaces  33   a / 34   a  on the upper spacer  31 /lower spacer  32  and the inner surface  35  of the belt  2  is smaller than the diameter φd of the rolling elements  5 , so that the rolling elements  5  are retained in the holes  21  of the belt  2  and do not tilt and shift. The rolling elements  5  do not interfere with the circulating passage. When the directions N 1 , N 2  of the openings  39  of the spherical mounting surfaces  33   a ,  34   a  are tilted relative to the horizontal direction “H” of the belt  2  by larger angle, the areas of the spherical mounting surfaces  33   a ,  34   a  are larger, and more retaining force to the rolling elements  5  in the vertical direction “V” of the belt  2  as shown in  FIG. 3 . 
     As shown in  FIG. 3 , the direction N 1 /N 2  of the opening  39  of the top mounting surface  37 /lower mounting surface  38  is located between the vertical direction “V” and the horizontal direction “H” of the belt  2 , so that when the retainer belt  1  is manufactured by way of injection molding, the rolling element retainer belt  1  is separated from the molds at an angle and the rolling element retainer belt  1  can be obtained in one time. As shown in  FIGS. 1 and 2 , a part of the smooth surface  33 / 34  of the upper/lower spacer  31 / 32  extends from the opening  39  in tangent direction and forms a curved surface  33   b / 34   b  which can be a cylindrical or cone-shaped surface. Two recesses  4  are respectively defined between curved surfaces  33   b ,  34   b  of the smooth surfaces  33 ,  34  of the upper spacer  31  and the lower spacer  32  and the separation portion  22 . The space between the rolling element  5  and the upper pacer  31  and the cylindrical or cone-shaped curved surfaces  33   b ,  34   b  of the lower spacer  32  is used to receive lubricant or grease. 
     As shown in  FIG. 6 , when the rolling element retainer belt  1  mentioned above is used for a linear motion mechanism, such as a linear rail which has a rail  9  and a first passage  91  located on one side of the rail  9 . A block  10  is mounted to the rail  9  and has a second passage  101  which is located corresponding to the first passage  91 . Two end pieces  11  are on two ends of the block  10  and each end piece  11  has at least one direction changing passage  130 . One end of each of the direction changing passages  130  is connected to the second passage  101 , and the other end of each of the direction changing passages  130  is connected to the straight return passage  120 . A circulating passage  100  is formed by the second passage  101 , the direction changing passages  130  and the return passage  120 . The circulating passage  100  has an enclosed guide slot  110  defined therein. When the rolling element retainer belt  1  and the rolling elements  5  in the holes  21  move in the circulating passage  100 , the two sides of the rolling element retainer belt  1  are guided in the guide slot  110  so as to ensure that the rolling element retainer belt  1  moves on the correct position. By the movement of the rolling elements  5  in the first passage  91  and the second passage  101 , the block  10  continuously moves along the first passage  91  of the rail  9 . 
     As shown in  FIG. 7 , the guide slot  110  defines a guide plane H 1  in the first and second passages  91 ,  101 , and a guide plane H 2  in the return passage  120 . The return passage  120  is not necessarily located on the perpendicular plane T 1  of the guide plane H 1 . The plane C 1  composed of the center of the rolling elements  5  in the return passage  120  and the center of the rolling elements  5  in the first and second passages  91 ,  101  has an angle φ 1  relative to the perpendicular plane T 1  of the guide plane H 1 . Therefore, the perpendicular plane T 1  of the guide plane H 1  and the perpendicular plane T 3  of the guide plane H 2  has a displacement Δ. When the rolling element retainer belt  1  enters into the direction changing passage  130  from the first and second passages  91 ,  101 , the rolling element retainer belt  1  deforms to generate resistance. 
     As shown in  FIG. 8 , for dealing with the resistance, the recesses  4  are respectively defined the upper spacer  31 , the lower spacer  32  and the separation portion  22 . When the rolling element retainer belt  1  enters into the direction changing passage  130 , the curved surfaces  33   b ,  34   b  of the upper and lower spacers  31 ,  32  partially deform toward the separation portion  22  of the belt  2  to reduce the resistance resulted from the displacement Δ of the direction changing passage  130 , and to provide sufficient force to retain the rolling elements  5  to move smoothly in the circulating passage  100 . Furthermore, the structural strength of the connection portions between the upper and lower spacers  31 ,  32  and the separation portion  22  is strong enough to bear the continuous deformation. 
     While we have shown and described the embodiment in accordance with the present invention, 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.