Patent Publication Number: US-2005133305-A1

Title: Lubricant draining device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a lubricant draining device.  
      2. Description of the Related Art  
      In a machine structure, such as a robot, a machine tool or an injection molding machine, a mechanical section including relatively movable mechanical parts is usually supplied with a lubricant, such as grease or oil. Especially, in a mechanical section formed in a closed space, such as a reduction mechanism, a wall defining the mechanical section is provided with a pouring port for pouring a new lubricant into the interior space of the mechanical section and a drain port for draining an old degraded lubricant from the interior space of the mechanical section.  
      In the closed mechanical section as described above, at the time when a lubricant is exchanged or replenished, a grease gun or other tool is used to pour a new lubricant into the interior space of the mechanical section through the pouring port under pressure. An old degraded lubricant in the mechanical section is ejected through the drain port in such a manner as to be pushed out by the new lubricant poured into the mechanical section. Whether or not the mechanical section is fully filled with the new lubricant can be judged by observing a change in the color of the lubricant discharged through the drain port. In other words, at an instant when the color of the discharged lubricant is changed from a degraded color to a fresh color, an operator can judge that the lubricant has been completely exchanged to new one, and thereby can stop pouring the new lubricant into the mechanical section and close the drain port with a plug.  
      In the lubricant exchanging operation as described above, the old lubricant pushed out through the drain port flows down or flows out. The flowing-down lubricant may soil the machine structure or a floor surface on which the machine structure is placed. Therefore, after the lubricant exchanging operation is completed, it is generally required to wipe off the old lubricant drained from the mechanical section by a hand work. If the wiping off of the drained lubricant is omitted, several disadvantages may be caused such that an object to be handled by the machine structure, such as a workpiece or a product, is soiled by the lubricant, or that the floor surface on which the machine structure is placed becomes slippery and thereby the safety of the environment is impaired. Indeed, various peripheral devices, jigs, wires, pipes, and so on, are often disposed around the machine structure and, therefore, it is generally difficult for the operator to wipe off the drained lubricant by hand work.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a lubricant draining device in which, when a lubricant supplied to the mechanical section of a machine structure is exchanged or replenished, it is possible to simplify or eliminate a subsequent work, such as a cleaning, which would normally be conducted after a lubricant exchanging operation.  
      To accomplish the above object, the present invention provides a lubricant draining device for draining a lubricant from a closed mechanical section provided in a machine structure such as a robot, a machine tool and an injection molding machine, comprising a wall defining the mechanical section, the wall including a drain port communicated with an interior space of the mechanical section while permitting a lubricant to flow therethrough; a tube connected at a proximal end thereof to the drain port and permitting a lubricant to flow therethrough; a blocking member blocking a flow of a lubricant through the tube in a releasable manner; and a retaining section retaining the tube at a location adjacent to the wall with the tube being kept connecting with the drain port.  
      In the above lubricant draining device, the retaining section may comprise a chamber, provided on the wall, for accommodating the tube in its entirety with the tube being removable from the chamber.  
      In this arrangement, the chamber may be provided with a detachable cover.  
      Alternatively, the chamber may be provided with a cover including an aperture for locally opening the chamber, and the tube may be provided at a distal end thereof with a flange capable of being fitted in the aperture of the cover.  
      The retaining section may also comprise a member, provided on the wall, for anchoring the tube with the tube being removable from the member.  
      The blocking member may comprise a plug detachably attached to a distal end of the tube.  
      Alternatively, the blocking member may comprise a squeezing member for restorably deforming a distal end of the tube.  
      Alternatively, the blocking member may comprise a valve arranged at a distal end of the tube.  
      The tube may is flexible. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects, features and advantages of the present invention will become more apparent from the following description of preferred embodiments in connection with the accompanying drawings, wherein:  
       FIG. 1  is a perspective view schematically showing a joint section of a robot, to which a lubricant draining device according to the first embodiment of the present invention is applied;  
       FIG. 2  is a perspective view schematically showing the lubricant draining device of  FIG. 1  with a cover removed;  
       FIG. 3  is a sectional view schematically showing the robot joint section of  FIG. 1 ;  
       FIG. 4  is a perspective view schematically illustrating a lubricant exchanging operation performed in the lubricant draining device of  FIG. 1 ;  
       FIG. 5  is a sectional view schematically showing the robot joint section during the lubricant exchanging operation of  FIG. 4 ;  
       FIG. 6  is a perspective view schematically showing a joint section of a robot, to which a lubricant draining device according to the second embodiment of the present invention is applied;  
       FIG. 7  is a sectional view schematically showing the robot joint section of in  FIG. 6 ;  
       FIG. 8  is a perspective view schematically illustrating a lubricant exchanging operation performed using the lubricant draining device of  FIG. 6 ;  
       FIG. 9  is a perspective view schematically showing a joint section of a robot, to which a lubricant draining device according to the third embodiment of the present invention is applied;  
       FIG. 10  is a view showing the lubricant draining device of  FIG. 9 , with a tube therein omitted to simplify an explanation;  
       FIG. 11  is a perspective view schematically showing a joint section of a robot, to which a lubricant draining device according to the fourth embodiment of the present invention is applied;  
       FIG. 12  is a view showing the lubricant draining device of  FIG. 11 , with a tube therein omitted to simplify an explanation;  
       FIG. 13  is a perspective view schematically showing an example of a tube blocking member;  
       FIG. 14  is a perspective view schematically showing another example of a tube blocking member; and  
       FIG. 15  is a perspective view schematically showing a further example of a tube blocking member. 
    
    
     DETAILED DESCRIPTION  
      The embodiments of the present invention are described below in detail, with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by common reference numerals.  
      In each of the illustrated embodiments, a lubricant draining device according to the present invention is provided for a reduction mechanism incorporated in a joint section of a robot. The present invention exhibits a significant utility in various mechanical structures, especially in a robot, a machine tool and an injection molding machine, for the purpose of exchanging or replenishing a lubricant in connection with a closed mechanical section including relatively movable mechanical parts.  
      Referring to the drawings, FIGS.  1  to  3  respectively show a lubricant draining device  10 , according to the first embodiment of the present invention, and a robot joint section  12  in which the lubricant draining device  10  is arranged.  
      In the robot joint section  12  as illustrated, a robot base  14  is provided with an electric motor  18  and a reduction mechanism  20 , used for driving an arm  16 . An output shaft of the electric motor  18  is connected to an input shaft of the reduction mechanism  20 . The arm  16  is attached to an output shaft of the reduction mechanism  20 , and thus is driven by a rotary power of the electric motor  18  with its speed reduced through the reduction mechanism  20 .  
      The reduction mechanism  20  includes mechanical parts built therein, such as an internal gear, an external gear, a cam, and so on, and these mechanical parts are mutually engaged with each other to be relatively movable. The mechanical parts of the reduction mechanism  20  are received in a space defined by the robot base  14 , the arm  16 , the electric motor  18  and a casing  22 , so that the reduction mechanism  20  constitutes a closed mechanical section.  
      The lubricant draining device  10 , according to the first embodiment of the present invention, is configured to drain a lubricant from the reduction mechanism  20 , and includes a wall  24  defining the reduction mechanism  20  and including a drain port  26  communicated with an interior space of the reduction mechanism  20  while permitting a lubricant to flow therethrough, a tube  28  connected at a proximal end thereof to the drain port  26  and permitting a lubricant to flow therethrough, a blocking member  30  blocking a flow of a lubricant through the tube  28  in a releasable manner, and a retaining section  32  retaining the tube  28  at a location adjacent to the wall  24  with the tube  28  being kept connecting with the drain port  26 .  
      The wall  24  defining the reduction mechanism  20  is provided at one end of the arm  16 , and the drain port  26  for draining the lubricant from the reduction mechanism  20  is formed above the center axis  20   a  of the reduction mechanism  20  so as to penetrate through the wall  24 . On the other hand, an end wall  34  of the robot base  14 , which is another wall defining the reduction mechanism  20 , is provided with a pouring port  36  for supplying the lubricant to the reduction mechanism  20 , the pouring port  36  being formed under the center axis  20   a  of the reduction mechanism  20  (or just beneath the electric motor  18 ) so as to penetrate through the end wall  34 . A nipple  38  is attached to the pouring port  36 .  
      The tube  28  is preferably flexible in its entirety, and is provided with a lubricant passage  40  communicated with the interior space of the reduction mechanism  20  through the pouring port  36 . The tube  28  is connected at one end (or a proximal end) thereof to the drain port  26  through a joint  42 . At another end (or a distal end) of the tube  28 , a stopper or plug (as described later), constituting the blocking member  30 , is detachably attached thereto through a joint  44 , so as to close the lubricant passage  40  in an openable manner.  
      The retaining section  32  includes a chamber  46 , provided on the wall  24 , for accommodating the tube  28  in its entirety in such a manner as to allow the tube  28  to be taken out of or removed from the chamber  46 . The chamber  46  is formed inside an annular wall portion  48  protruding from the outer surface of the wall  24  at a side opposite to the reduction mechanism  20 . The chamber  46  is provided with a detachable cover  50 . The cover  50  is usually secured to the outer end face  48   a  of the annular wall portion  48  by bolts or magnets (not shown) to close the chamber  46  and, when the lubricant should be exchanged or replenished as described later, is detached from the annular wall portion  48  to open the chamber  46 . The tube  28  is usually bent or folded in an appropriate fashion to be accommodated in the chamber  46  ( FIG. 2 ), and is hidden by the cover  50  attached to the annular wall portion  48  so as not to be visible from the outside thereof ( FIGS. 1 and 3 ).  
      In the above configuration, at the time when the lubricant is to be exchanged or replenished, for the reduction mechanism  20 , a collecting container  52  is provided, as shown in  FIGS. 4 and 5 , and the cover  50  is detached so as to permit the tube  28  to be drawn out of the chamber  46 . Then, the distal end (i.e., the joint  44 ) of the tube  28  extending outside the chamber  46  is introduced into the collecting container  52 , and in this state, the blocking member  30  ( FIG. 2 ) is detached from the joint  44 . After that, a grease gun  54  is connected to the grease nipple  38 , and is operated to supply a new lubricant into the interior space of the reduction mechanism  20  through the pouring port  36 .  
      When the new lubricant is poured into the reduction mechanism  20  under pressure by the grease gun  54 , an old degraded lubricant in the reduction mechanism  20  is ejected from the end opening of the tube  28  through the drain port  26  and the passage  40 , in such a manner as to be pushed out by the new lubricant, and is stored in the collecting container  52 . At this time, a change in the color of the lubricant discharged from the end opening of the tube  28  is observed. Then, at an instant when the color of the discharged lubricant is changed from a degraded color to a fresh color, an operator judges that the lubricant has been completely exchanged to new one, and thereby stops pouring the new lubricant and closes the end opening of the tube  29  again by the blocking member  30 . After that, the tube  28  is accommodated in the chamber  46 , the cover  50  is attached, and thereby the exchanging operation of the lubricant is completed.  
      As described above, in the lubricant draining device  10 , it is possible to readily and surely collect or store the lubricant drained from the reduction mechanism  20  in the collecting container  52  by using the tube  28 . Accordingly, it is possible to prevent the robot, or the floor on which the robot is placed, from being soiled, and thus to significantly simplify or eliminate subsequent work, such as cleaning, which would, otherwise, be conducted after the lubricant exchanging operation.  
       FIGS. 6 and 7  show a lubricant draining device  60 , according to the second embodiment of the present invention, and a robot joint section  12  in which the lubricant draining device  60  is arranged. The configuration of the lubricant draining device  60  of the second embodiment is substantially the same as that of the lubricant draining device  10  of the first embodiment described above, except for the constitutions of a joint  44  attached to the distal end of a tube  28  as well as of a cover  50  in a retaining section  32 . Accordingly, corresponding components are denoted by common reference numerals, and the descriptions thereof are not repeated.  
      In the lubricant draining device  60 , the joint  44  attached to the distal end of the tube  28  includes a flat-plate like rectangular flange  62 . The cover  50  of the chamber  46  includes an aperture  64 , formed at a desired position to penetrate through the cover  50 , into which the flange  62  is detachably fitted ( FIG. 7 ). In a state where the flange  62  of the joint  44  is not fitted in the aperture  64  or the cover  50 , the aperture  64  locally opens the chamber  46  ( FIG. 8 ).  
      At the time when the lubricant is to be exchanged or replenished for the reduction mechanism  20 , in the second embodiment, the joint  44  is detached from the cover  50 , as shown in  FIG. 8 , and the tube  28  is drawn cut from the chamber  46  through the aperture  64 . Then, the distal end (i.e., the joint  44 ) of the tube  28  is introduced into the collecting container  52 , and in this state, the blocking member  30  ( FIG. 7 ) is detached. After that, a new lubricant is poured into the interior space of the reduction mechanism  20  by using a grease gun  54  in the same manner as the first embodiment. Thus, an old degraded lubricant is drained from the end opening of the tube  28 , and is stored in the collecting container  52 . At an instant when the color of the drained lubricant is changed from a degraded color to a fresh color, an operator stops pouring the new lubricant and closes the end opening of the tube  28  again by the blocking member  30 . After that, the tube  28  is accommodated in the chamber  46 , the flange  62  of the joint  44  is fitted into the aperture  64  of the cover  50 , and thereby the exchanging operation of the lubricant is completed.  
      As will be understood from the above, the lubricant draining device  60  can also possess remarkable effects equivalent to those in the lubricant draining device  10  described above. Especially, in the lubricant draining device  60 , there is no need to attach or detach the cover  50  in the retaining section  32  when the lubricant is exchanged or replenished, so that the operation becomes easy in comparison with the lubricant draining device  10 .  
       FIGS. 9 and 10  show a lubricant draining device  70 , according to the third embodiment of the present invention, and a robot joint section  12  in which the lubricant draining device  70  is arranged. The configuration of the lubricant draining device  70  of the third embodiment is substantially the same as that of the lubricant draining device  10  of the first embodiment described above, except for the constitution of a retaining section  32  for retaining a tube  28 . Accordingly, corresponding components are denoted by common reference numerals, and the descriptions thereof are not repeated.  
      In the lubricant draining device  70 , the retaining section  32  includes an anchoring member  72 , provided on the wall  24  of an arm  16 , for anchoring the tube  28  in such a manner as to allow the tube  28  to be detached or removed from the anchoring member  72 . The anchoring member  72  is composed of a hook-shaped member fixed to the outer surface of the wall  24  at a side opposite to a reduction mechanism  20 . More specifically, as shown in  FIG. 10 , the anchoring member  72  includes a hook  74  arranged in close proximity to a joint  42  (or a drain port  26  shown in  FIG. 3 ). The tube  28  is usually bent or folded in an appropriate fashion to be bundled preferably by a band  76 , and is anchored in this condition on the hook  74  of the anchoring member  72  by using, e.g., the band  76  ( FIG. 9 ). In this embodiment, the tube  28  is always exposed.  
      At the time when the lubricant is to be exchanged or replenished for the reduction mechanism  20 , in the third embodiment, the band  76  is removed as occasion demands, and the tube  28  is detached from the anchoring member  72  to permit the tube  28  to be drawn out of the arm  16 . Ther., the distal end (i.e., the joint  44 ) of the tube  28  extending outward of the arm  16  is introduced into the collecting container  52  ( FIG. 4 ), and in this state, the blocking member  30  is detached. Then, in the same manner as the first embodiment, the lubricant is exchanged or replenished. At an instant when the color of the lubricant drained from the tube  28  is changed from a degraded color to a fresh color, an operator stops pouring the new lubricant and closes the end opening of the tube  28  again by the blocking member  30 . After that, the tube  28  is bundled and anchored onto the anchoring member  72  by optionally using the band  76 , and thereby the exchanging operation of the lubricant is completed.  
      As will be understood from the above, the lubricant draining device  70  can also possess remarkable effects equivalent to those in the lubricant draining device  10  described above. Especially, in the lubricant draining device  70 , there is no need to attach or detach the cover  50  ( FIG. 1 ) in the retaining section  32  when the lubricant is exchanged or replenished, so that the operation becomes easy in comparison with the lubricant draining device  10 .  
       FIGS. 11 and 12  show a lubricant draining device  30 , according to the fourth embodiment of the present invention, and a robot joint section  12  in which the lubricant draining device  80  is arranged. The configuration of the lubricant draining device  80  of the forth embodiment is substantially the same as that of the lubricant draining device  70  of the third embodiment described above, except for the constitution of an anchoring member in a retaining section  32 . Accordingly, corresponding components are denoted by common reference numerals, and the descriptions thereof are not repeated.  
      The anchoring member  82  of the lubricant draining device  80  is composed of a holder-shaped member fixed to the outer surface of a wall  24  at a side opposite to a reduction mechanism  20 . More specifically, as shown in  FIG. 12 , the anchoring member  82  includes a holder  34  arranged in close proximity to a joint  42  (or a drain port  26  shown in  FIG. 3 ). The holder  84  is engaged due to a spring function thereof with a joint  44  attached to the distal end of the tub  28  to hold the joint  44 . The tube  28  is usually held in a tight condition by, e.g., winding it around the anchoring member  82 , and is anchored in this condition on she anchoring member  82  by engaging the joint  44  at the distal end of the tube  28  with the holder  84 .  
      At the time when the lubricant is to be exchanged or replenished for the reduction mechanism  20 , in the fourth embodiment, the joint  44  is detached from the holder  84  and thus the tube  28  is separated from the anchoring member  82  to permit the tube  28  to be drawn out of the arm  16 . The operation subsequent thereto is the same as that of the third embodiment. In the lubricant draining device  80 , remarkable effects equivalent to those in the lubricant draining device  70  described above can also be obtained.  
       FIG. 13  shows, in an enlarged manner, the configuration of the distal end of the tube  28  in each of the embodiments described above. The joint  44  is attached to the distal end of the tube  28 , and the blocking member  30  formed from a stopper or plug is detachably attached to the end of the joint  44 .  
      The other blocking member may be used in each embodiment. For example, as shown in  FIG. 14 , in the case where the tube  28  is made of a sufficiently elastic material at, at least, the distal end length thereof, a squeezing member  90 , such as a clip, may be used for restorably deforming the distal end of the tube  28 , so as to close the passage  40  of the tube  28 . Alternatively, as shown in  FIG. 15 , a valve  92  may be arranged at the distal end of the tube  28 , so as to permit the passage of the tube  28  to be opened or closed by operating the valve  92 .  
      While the invention has been described with reference to specific preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made thereto without departing from the spirit and scope of the following claims.