Abstract:
A motion transmission module with a cooling device is aimed at solving the disadvantage of the conventional motion transmission module that the cooling structure of the conventional motion transmission module would increase the length or outer diameter of the nut. The nut is formed with a flat surface for mounting the cooling device, so that the length of the nut won&#39;t be increased. Furthermore, the cooling device also serves as a positioning block to fix the return member, it doesn&#39;t increase the outer diameter of the nut.

Description:
This application is a continuation in part of U.S. patent application Ser. No. 13/251,244, which claims the benefit of the earlier filing date of Oct. 1, 2011. Claims 1-2 of this application are revised from claim 1 of the U.S. patent application Ser. No. 13/251,244. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a motion transmission module, and more particularly to a motion transmission module with a cooling device. 
     2. Description of the Prior Art 
     When a motion transmission module (such as ball or roller screw) is used in heaving load conditions, with the increase in axial load, the temperature of the nut will also increase, which will affect the running accuracy. Hence, the existing nuts are normally provided with a cooling system. 
     Referring to  FIG. 1 , a conventional technique for cooling the nut of a ball screw is shown, wherein the nut  11  is formed with a plurality of straight holes  111  and arc-shaped grooves  112 , and at the front end and flange end of the nut  11  are disposed anti-leak cushions  113  and an end cap  114 , so as to form a cooling system. 
     Since it has to arrange the end cap  114  at the end surface of this cooling nut, the length of the nut  11  must be increased (as compared to the nut without cooling system), which will result in the reduction of the travel length of the ball screw or roller screw equipped with such cooling nut. 
     As shown in  FIG. 2 , another conventional nut cooling structure is shown, wherein the nut  12  is formed with an inlet  121  and an outlet  122  for inputting and discharging of cooling liquid, and an outer cover  13  is mounted on the nut  12  to form a cooling groove  14 , and then two O-rings  15 ,  16  are used to prevent the cooling liquid leakage. 
     The outer cover  13  increases the outer diameter of the nut  12  as compared to the nut without cooling system, so that it is inconvenient to the user who uses the ball or roller screw which was originally equipped with a non-cooling-system nut, since it has to redesign the nut mounting seat when the non-cooling-system nut is replaced with a cooling nut of the same size. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide a motion transmission module with a cooling device, wherein the temperature of the nut can be cooled down without changing the length of the nut and redesigning the nut mounting seat. 
     Another object of the present invention is to provide a motion transmission module with a cooling device, wherein the temperature of the nut can be cooled down without changing the outer diameter of the nut and without redesigning the nut mounting seat of the machine. 
     To achieve the above object, a motion transmission module with a cooling device in accordance with the present invention comprises a screw, a nut, a return member, a plurality of rolling elements, and a cooling device. 
     The screw a screw formed with an outer helical groove. The nut includes a body, a penetrating hole penetrating through the body and provided for insertion of the screw, an inner helical groove formed in an inner surface of the hole to define a load path by cooperating with the outer helical groove, a flat surface formed on an outer surface of the body, and two through holes defined in the flat surface and in communication with the inner helical grooves. The return member includes two legs inserted in the two through holes and a return path running through the two legs. The plurality of rolling elements is movably received in the load path and the return path. The cooling device is fixed on the body of the nut and has a mounting surface to be abutted against the flat surface, a cooling circulation system, and a positioning groove formed in the mounting surface. At a front end of the cooling circulation system is formed an inlet which is located on a peripheral surface of the cooling device, and at a rear end of the cooling circulation system is formed an outlet which is located on a peripheral surface of the cooling device, the positioning groove is formed with a bottom to be abutted against the return member. The cooling circulation system is formed by machining process, the cooling circulation system includes a plurality of transverse passages, and longitudinal passages, the inlet is located in a last one of the transverse passages, and the outlet is located in a first one of the transverse passages. The transverse passages, the longitudinal passages, the outlet and the inlet are in communication with one another to form a single route, and then the transverse and longitudinal passages are sealed with sealing members to prevent leakage of cooling liquid, so as to form the cooling circulation system with the inlet and outlet. 
     To achieve the above object, another motion transmission module with a cooling device in accordance with the present invention comprises a screw, a nut, a return member, a plurality of rolling elements, and a cooling device. The screw is formed with an outer helical groove. The nut includes a body, a penetrating hole penetrating through the body and provided for insertion of the screw, an inner helical groove formed in an inner surface of the hole to define a load path by cooperating with the outer helical groove, a flat surface formed on an outer surface of the body, and two through holes defined in the flat surface and in communication with the inner helical grooves. The return member includes two legs inserted in the two through holes and a return path running through the two legs. The plurality of rolling elements is movably received in the load path and the return path. The cooling device is fixed on the body of the nut and has a mounting surface to be abutted against the flat surface, a cooling circulation system, and a positioning groove formed in the mounting surface. At a front end of the cooling circulation system is formed an inlet which is located on a peripheral surface of the cooling device, and at a rear end of the cooling circulation system is formed an outlet which is located on a peripheral surface of the cooling device, the positioning groove is formed with a bottom to be abutted against the return member. The cooling circulation system of the cooling device is an integrally formed U-shaped passage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustrative view of a conventional nut cooling structure; 
         FIG. 2  shows another conventional nut cooling structure; 
         FIG. 3  is an exploded view of a motion transmission module with a cooling device in accordance with the present invention; 
         FIG. 4  is an assembly view of the motion transmission module with a cooling device in accordance with the present invention; 
         FIG. 5  is a cross sectional view taken along the line  4 - 4  of  FIG. 4 ; 
         FIG. 6  is a perspective view of the cooling device in accordance with a first embodiment of the present invention; 
         FIG. 7  is a perspective view of the cooling device in accordance with a second embodiment of the present invention; 
         FIG. 8  is an exploded view of a motion transmission module with a cooling device in accordance with another embodiment of the present invention; 
         FIG. 9  is an assembly view of the motion transmission module with a cooling device in accordance with another embodiment of the present invention; and 
         FIG. 10  is a cross sectional view taken along the line  10 - 10  of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
     Referring to  FIGS. 3-6 , a motion transmission module with a cooling device in accordance with a first preferred embodiment of the present invention comprises: a screw  20 , a nut  30 , a return member  40 , a plurality of rolling elements  50 , and a cooling device  60 . 
     The screw  20  is formed with an outer helical groove  21 . 
     The nut  30  includes a body  31 , a head  32  (namely the flange), a penetrating hole  33  which penetrates through the head  32  and the body  31  and is provided for insertion of the screw  20 , an inner helical groove  331  formed in the inner surface of the hole  33  to define a load path  71  by cooperating with the outer helical groove  21 , a flat surface  311  formed on the outer surface of the body  31 , and two through holes  312  defined in the flat surface  311  and in communication with the inner helical grooves  331 . 
     The return member  40  includes two legs  41  inserted in the two through holes  312  and a return path  42  running through the legs  41 . 
     The rolling elements  50  are movably received in the load path  71  and the return path  42 . 
     The cooling device  60  is in the form a block to be fixed on the flat surface  311  of the body  31  of the nut  30  by screws  72  (or by any other possible means, such as pins, locking, or rings) and includes a mounting surface  61  to be abutted against the flat surface  311 , a cooling circulation system  62  in the form of a single route, and a positioning groove  63  formed in the mounting surface  61 . The positioning groove  63  is formed with a bottom  631  to be abutted against the return member  40 . 
     When the cooling circulation system  62  of the cooling device  60  is formed by machining process and includes a plurality of transverse passages  621 , a longitudinal passages  622  in the form of a single route for connecting the transverse passages  621  with one another, an outlet  623  connected to a cooling machine (not shown) and an inlet  624  for inputting and discharging of the cooling liquid, respectively. The transverse and longitudinal passages  621 ,  622 , namely at the surface of the cooling device  60 , are sealed with sealing members  73  (headless screws or copper plugs or by other sealing means) to prevent leakage of cooling liquid so as to form the cooling circulation system  62  with the outlet  623  and the inlet  624 . 
     It is to be noted that the inlet  624  is the front end of the cooling circulation system  62  and located on the peripheral surface of the cooling device  60 , in other words, the inlet  624  is located in the last one of the transverse passages  621 . The outlet  623  is the rear end of the cooling circulation system  62  and located on the peripheral surface of the cooling device  60 , in other words, the outlet  623  is located in the first one of the transverse passages  621 . 
     The transverse passages  621 , the longitudinal passages  622 , the outlet  623  and the inlet  624  are in communication with one another to form a single route. 
     As shown in  FIG. 7 , which shows another embodiment of the present invention, wherein a cooling circulation system  81  of the cooling device  80  is integrally formed (by lost wax casting), and the cooling circulation system  81  is a U-shaped single passage including an outlet  811  and an inlet  812 . 
     When the motion transmission module is running, the cooling device  60  which is in contact with the flat surface  311  of the nut  30  can cools down the nut  30 , so as to prevent the running accuracy of the motion transmission module from being affected. Hence, the nut  30  can be cooled down without changing the length of the nut  30 , namely, the cooling device  60  doesn&#39;t increase the length of the nut  30 . 
     It is to be noted that since the outlet  623  and the inlet  624  of the cooling device  60  are connected to a cooling machine, cooling liquid can be outputted from the cooling machine and flows into the cooling circulation system  62  through the inlet  624  to absorb the heat energy transmitted to the cooling device  60  from the nut  30 , and finally the cooling liquid flow out of the outlet  623  to take the heat energy away from the cooling device  60 , thus cooling down the nut and maintaining the running accuracy of the motion transmission module. 
     Furthermore, since the cooling device  60  also serves as a positioning block to fix the return member  40 , it doesn&#39;t increase the outer diameter of the nut  30 . 
     The cooling device  60  is further formed with the positioning groove  63  to fix the return member  40 , and the bottom  631  of the positioning groove  63  is pressed against the return member  40 , so that the cooling device  60  can also cool down the return member  40 . 
     It is to be noted that, as shown in  FIG. 6 , when the cooling circulation system  62  of the cooling device  60  takes the form of a single route formed by the plurality of transverse passages  621  and longitudinal passages  622 , and it can be made by machining process, and as shown  FIG. 7 , when the cooling circulation system  81  of the cooling device  80  is integrally formed, it can be made by lost wax casting. The cooling circulation system is normally fixed to the nut by screws no matter it is made by machining process or lost wax casting. As shown in  FIGS. 8-10 , a cooling circulation system  90  in accordance with another embodiment of the present invention is integrally provided with an elastic engaging portion  91  to be engaged with the body  31  of the nut  30  and also has a mounting surface  92  abutted against the flat surface  311  of the nut  30  and a bottom  93  abutted against the return member  40 . In this embodiment, the body  31  of the nut  30  is formed with an engaging groove  313  for engaging with the engaging portion  91  of the cooling circulation system  90 . 
     While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.