Abstract:
A linear motion apparatus has a linear track, a slider and two sliding-assistant units for a linear motion apparatus. The sliding-assistant units for a linear motion apparatus is mounted between the track and the slider to enhance ease of movement between the track and the slider, and each sliding-assistant unit has two roller rings to receive rollers. The roller rings are elongated rectangular rings, are selectively mounted oppositely crossly around each other. Each roller ring is designed with reduced components to make manufacturing and assembling the sliding-assistant unit easier. Moreover, the roller ring is designed as one unity so no seam will be formed due to assembling two different pieces, such that ensures contact between the rollers and the roller ring smooth.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention relates to a sliding-assistant unit, and more particularly to a sliding-assistant unit for a linear motion apparatus. 
   2. Description of the Related Art 
   A sliding-assistant unit is applied between a slider and a linear track of a linear motion apparatus to help the slider sliding along the linear track for transferring things and reducing noise and friction during the linear motion apparatus being operated. 
   A conventional sliding-assistant unit as shown in FIG. 1 of U.S. Pat. No. 6,729,760B2 is applied on a slider ( 2 ) to help the slider to move along a track ( 1 ). However, components of the conventional sliding-assistant unit are complicated. Additionally, each component of the conventional sliding-assistant unit is different to others, such that the assembling and manufacturing of the conventional sliding-assistant unit are difficult and complicated. 
   Another conventional sliding-assistant unit disclosed in US publication 2006/0072862 is mounted on a slider ( 20 ) and includes four U-shaped roller rings ( 30 ) to receive multiple rollers ( 51 ) inside with each roller ( 51 ) being partially exposed out to contact a track ( 10 ). Although components of the conventional sliding-assistant unit are much simplified, but each U-shaped roller ring ( 30 ) is assembled by two half shells as shown in  FIGS. 3 to 5 . Thus, a seam will be formed between the two half shells and then causes non-smoothness of an inner surface of the roller ring ( 30 ). Consequently, friction between the roller ring ( 30 ) and the rollers ( 51 ) will be further increased due to non-smoothness of the inner surface of the roller ring ( 30 ). 
   To overcome the shortcomings, the present invention provides a sliding-assistant unit for a linear motion apparatus to mitigate or obviate the aforementioned problems. 
   SUMMARY OF THE INVENTION 
   The primary objective of the present invention is to provide a sliding-assistant unit for a linear motion apparatus, which has simplified structures and is formed as one unity. 
   A linear motion apparatus has a linear track, a slider and two sliding-assistant units for a linear motion apparatus. The sliding-assistant units for a linear motion apparatus are mounted between the track and the slider to enhance ease of movement between the track and the slider, and each sliding-assistant unit has two roller rings. The roller rings are elongated rectangular rings, are selectively mounted oppositely crossly around each other. Each roller ring is designed with reduced components to make manufacturing and assembling the sliding-assistant unit easier. Moreover, the roller ring is designed as one unity so no seam will be formed due to assembling two different pieces, such that ensures contact between the rollers and the roller ring smooth. 
   Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a linear motion apparatus; 
       FIG. 2  is an exploded perspective view of the linear motion apparatus in  FIG. 1 ; 
       FIG. 3  is a perspective view in partial section of the linear motion apparatus in  FIG. 1  with a sliding-assistant unit for a linear motion apparatus in accordance with the present invention; 
       FIG. 4  is a perspective view in partial section of the linear motion apparatus in  FIG. 1 ; 
       FIG. 5  is a front view in partial section of the linear motion apparatus in  FIG. 1 ; 
       FIG. 6  is a perspective view of a sliding-assistant unit for a linear motion apparatus in  FIG. 3 ; 
       FIG. 7A  is an exploded perspective view of the sliding-assistant unit for a linear motion apparatus in  FIG. 3 ; 
       FIG. 7B  is a partial enlarged perspective view of the sliding-assistant unit for a linear motion apparatus in  FIG. 3 ; 
       FIG. 8  is an enlarged partial front view in partial section of the linear motion apparatus in  FIG. 1 ; and 
       FIG. 9  is another enlarged partial front view in partial section of the linear motion apparatus in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 1 to 3 , a linear motion apparatus comprises a linear track ( 50 ), a slider ( 1 ) and two sliding-assistant units ( 4 ) in accordance with the present invention. 
   With further reference to  FIGS. 4 and 5 , the track ( 50 ) is elongated and has two ends, an inner segment, a middle segment, an outer segment, an inner track protrusion, an outer track protrusion, two inner guiding paths ( 51 ) and two outer guiding paths ( 52 ). 
   The inner track protrusion is formed on and protrudes oppositely away from the inner segment of the track ( 50 ) and forms two opposite inclined edges between the inner segment and the middle segment. 
   The outer track protrusion is formed on and protrudes oppositely away from the outer segment of the track ( 50 ) and forms two opposite inclined edges between the outer segment and the middle segment. 
   The inner guiding paths ( 51 ) are straight and are respectively formed on the inclined edges of the inner track protrusion between the ends of the track ( 50 ). 
   The outer guiding paths ( 52 ) are straight and are respectively formed on the inclined edges of the outer track protrusion between the ends of the track ( 50 ). 
   The slider ( 1 ) is mounted slidably on the track ( 50 ) and has a sliding body ( 10 ) and two end caps ( 20 ). 
   The sliding body ( 10 ) is mounted slidably around the inner track protrusion of the track ( 50 ) and has an inner surface, two ends, two sides and two clamping walls ( 11 ). 
   The inner surface of the sliding body ( 10 ) corresponds to the inner segment of the track ( 50 ). 
   The clamping walls ( 11 ) are respectively formed on and protrudes from the inner surface of the sliding body ( 10 ) at the sides between the ends, are parallel to each other and together clamp the track ( 50 ). Each clamping wall ( 11 ) has an inner surface, a path protrusion, a first mounting hole ( 14 ) and a second mounting hole ( 15 ). 
   The path protrusion of each clamping wall ( 11 ) is formed on and protrudes from the inner surface of the clamping wall ( 11 ) between the ends of the sliding body ( 10 ), correspondingly face towards the middle segment of the track ( 50 ), is inclined symmetrically in transverse cross-section to form an inner path ( 12 ) and an outer path ( 13 ) and may have a hooking groove ( 16 ). 
   The inner path ( 12 ) of the path protrusion of each clamping wall ( 11 ) corresponds to and is parallel with the corresponding inner guiding path ( 51 ). 
   The outer path ( 13 ) of the path protrusion of each clamping wall ( 11 ) corresponds to and is parallel with the corresponding outer guiding path ( 52 ). 
   The hooking groove ( 16 ) is formed in the path protrusion between to the inner path ( 12 ) and the outer path ( 13 ). 
   The first mounting hole ( 14 ) of each clamping wall ( 11 ) is round in cross-section, is formed longitudinally through the clamping wall ( 11 ) and corresponds to and is parallel with the outer path ( 13 ) and the corresponding outer guiding path ( 52 ). 
   The second mounting hole ( 15 ) of each clamping wall ( 11 ) is round in cross-section, is formed longitudinally through the clamping wall ( 11 ) and corresponds to and is parallel with the inner path ( 12 ) and the corresponding inner guiding path ( 51 ). 
   The end caps ( 20 ) are mounted respectively on the ends of the sliding body ( 10 ) and each end cap ( 20 ) has two mounting recesses ( 21 ). 
   Each mounting recess ( 21 ) is formed in the end cap ( 20 ), may be formed as two elongated slots that cross each other and corresponds to and aligns with the inner path ( 12 ), the outer path ( 13 ), the first mounting hole ( 14 ) and the second mounting hole ( 15 ) of the corresponding clamping wall ( 11 ) and the corresponding inner guiding path ( 51 ) and outer guiding path ( 52 ). 
   With further reference to  FIGS. 6 ,  7 A and  7 B, the sliding-assistant units ( 4 ) for a linear motion apparatus in accordance with the present invention is mounted between the track ( 50 ) and the slider ( 1 ) and each sliding-assistant unit ( 4 ) comprises two roller rings ( 40 ). 
   The roller rings ( 40 ) are selectively mounted oppositely crossly around each other and each roller ring ( 40 ) has a frame ( 41 ), a roller assembly ( 45 ), a head cover ( 42 ) and a side cover ( 43 ). 
   The frame ( 41 ) of each roller ring ( 40 ) is an elongated rectangular ring, is resilient and has an elongated hole, a sliding-assistance bar ( 410 ), a mounting bar ( 411 ), an exposing bridge ( 412 ), a mounting head ( 413 ), a roller groove ( 400 ), a gap ( 4130 ) and two limiting protrusions ( 4102 ). 
   The elongated hole is formed through the frame ( 41 ). 
   With further reference to  FIG. 8 , the sliding-assistance bar ( 410 ) of one of the roller rings ( 40 ) corresponds to and is selectively mounted between the corresponding inner guiding path ( 51 ) and the corresponding inner path ( 12 ). The sliding-assistance bar ( 410 ) of the other roller ring ( 40 ) corresponds to and is selectively mounted between the corresponding outer guiding path ( 52 ) and the corresponding outer path ( 13 ). The sliding-assistance bar ( 410 ) has an inner side, an elongated opening ( 4100 ) and an optional hook protrusion ( 4101 ). The elongated opening ( 4100 ) is formed through the sliding-assistance bar ( 410 ). The hook protrusion ( 4101 ) is formed on and protrudes inwardly from the inner side of the sliding-assistance bar ( 410 ) and corresponds to and selectively engages the hooking groove ( 16 ) to further hold the sliding-assistance bar ( 410 ) in position. 
   The mounting bar ( 411 ) is parallel with the sliding-assistance bar ( 410 ) and corresponds to and is selectively mounted through one first mounting hole ( 14 ) or one second mounting hole ( 15 ). 
   The exposing bridge ( 412 ) connects between the sliding-assistance bar ( 410 ) and the mounting bar ( 411 ) and cooperates with the sliding-assistance bar ( 410 ) and the mounting bar ( 411 ) to form a U-shaped mount. The U-shaped mount has a width. The width corresponding to a thickness of the frame ( 41 ). 
   The mounting head ( 413 ) is parallel with the exposing bridge ( 412 ), protrudes from the sliding-assistance bar ( 410 ) and corresponds to the mounting bar ( 411 ) and has two opposite outside surfaces, a proximal end, a heading edge, two mounting recesses ( 4133 ) and a mounting slot ( 4131 ). 
   The mounting recesses ( 4133 ) are respectively formed in the opposite outside surfaces of the mounting head ( 413 ) adjacent to the heading edge. 
   The mounting slot ( 4131 ) is formed in the proximal end of the mounting head ( 413 ) from the heading edge. 
   The gap ( 4130 ) is formed between the mounting head ( 413 ) and the mounting bar ( 411 ). Therefore, an user can bend the mounting bar ( 411 ) outward to enlarge the gap ( 4130 ) first then mount the mounting bar ( 411 ) through the first hole ( 14 ) or the second hole ( 15 ) while assembling, also two frames ( 41 ) are able to be mounted around each other due to the gap ( 4130 ). 
   With further reference to  FIG. 9 , the roller groove ( 400 ) is formed in and around the frame ( 41 ) and has an opening. 
   The limiting protrusions ( 4102 ) are oppositely formed in the sliding-assistance bar ( 410 ) to prevent the rollers ( 451 ) from falling off. 
   The roller assemblies ( 45 ) of the sliding-assistant unit ( 4 ) are respectively mounted in the roller grooves ( 400 ) of the frames ( 41 ) of the sliding-assistant unit ( 4 ) and each has a resilient belt ( 450 ) and multiple rollers ( 451 ). 
   The rollers ( 451 ) are cylinders, are parallelly mounted rollably in a column along the resilient belt ( 450 ), are mounted rollably in the roller groove ( 400 ) of the frame ( 41 ) and are partially exposed out from the roller groove ( 400 ) and the elongated opening in the sliding-assistance bar ( 410 ) to touch and roll between the inner guiding path ( 51 ) and the inner path ( 12 ) or the outer guiding path ( 52 ) and outer path ( 13 ) to reduce friction of movement between the slider ( 1 ) and the track ( 50 ). 
   The head cover ( 42 ) is mounted detachably on the mounting head ( 413 ) to prevent the roller assembly ( 45 ) from falling off, corresponds to and is selectively mounted in the U-shaped mount of the frame ( 41 ) and has an end, two tabs ( 420 ) and an engager ( 421 ). 
   The two tabs ( 420 ) are formed on and protrude from the head cover ( 42 ) and correspond to and selectively engage the mounting recesses ( 4133 ) to hold the head cover ( 42 ) on the mounting head ( 413 ). 
   The engager ( 421 ) is formed on and protrudes from the head cover ( 42 ) and corresponds to and selectively engages the mounting slot ( 4131 ) to hold the head cover ( 42 ) on the mounting head ( 413 ). 
   The side cover ( 43 ) is elongated, is mounted detachably on the mounting bar ( 411 ) to prevent the roller assembly ( 45 ) from falling off and has an inner surface, an outer surface, two outer side-edges, a receiving groove ( 430 ), an oil groove ( 431 ) and multiple oil holes ( 432 ). 
   The outer surface is flat and distances from an inner surface of one first mounting hole ( 14 ) or one second mounting hole ( 15 ) when the mounting bar ( 411 ) is mounted in the first mounting hole ( 14 ) or the second mounting hole ( 15 ) such that allows lubricant to be added into the first mounting hole ( 14 ) or the second mounting hole ( 15 ). 
   The outer side-edges are oppositely adjacent to the outer surface, are curved and selectively abut to and fit the inner surface of one first mounting hole ( 14 ) or one second mounting hole ( 15 ) so presses the side cover ( 43 ) securely on the mounting bar ( 411 ). 
   The receiving groove ( 430 ) is formed in the inner surface of the side cover ( 43 ) to receive the roller assembly ( 45 ) and has a bottom. 
   The oil groove ( 431 ) is formed in the bottom of the receiving groove ( 430 ). 
   The oil holes ( 432 ) are formed through the side cover ( 43 ) and communicate with the oil groove ( 431 ) to allow lubricant to be added on the roller assembly ( 45 ) when the mounting bar ( 411 ) is mounted in the first mounting hole ( 14 ) or the second mounting hole ( 15 ). 
   Consequently, components of the sliding-assistant unit ( 4 ) are much simplified such that manufacturing and assembling of the sliding-assistant unit ( 4 ) becomes much easier. In addition, because there is no seam that will be formed on surface of the roller groove ( 400 ), so contact between the roller groove ( 400 ) and the rollers ( 451 ) will be smooth. Even though the gap ( 4130 ) is formed on the frame ( 41 ) for assembling the sliding-assistant unit ( 4 ), but continuing surface of the roller groove ( 400 ) at the gap ( 4130 ) is kept flat after assembling so will not generate negative influence to the smoothness of the contact. 
   Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.