Abstract:
The present invention provides a robot that can use an inexpensive connector and keep the connector assembly dust-free and safe. A base of a robot mechanical unit has a hollow structure. An opening is provided on a lateral surface of the base, a through-hole is provided on a closing member that covers the opening, and a cable mounting member provided with a through-hole is fixed on the closing member. A connecting cable from a control unit passes through the through-holes and is connected to robot mechanical unit-internal cables by a cable connector inside the base. The robot mechanical unit-internal cables are fixed by a cable clamp inside the base and a swivel body. The connector is installed inside the base and suspended in space, providing superior dust-proofing. No external force is applied, and so an inexpensive configuration can be achieved that does not require an especially strong connector. Moreover, the connector can be connected and disconnected easily.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a robot, and more particularly to an industrial robot having features in cable connection.  
           [0003]    2. Description of Related Art  
           [0004]    In industrial and other robots, typically, a robot mechanical unit and a control unit that controls the robot mechanical unit are arranged separately, with the robot mechanical unit-internal cables and the control unit electrically connected to each other by a connecting cable. The robot mechanical unit-internal cables electrically connect the connecting cable to the individual servomotors that drive the joints of the robot mechanical unit. By transmitting operating commands from the control unit through the connecting cable to the individual servomotors, the robot mechanical unit can be made to perform a desired operation.  
           [0005]    For example, JP 8-1574A describes a robot in which a connecting cable extending from an interior of the control unit is connected to an internal cable of the robot mechanical unit by a connector at a lateral surface of a base of the robot mechanical unit. Further, JP 8-1574A also discloses, with respect to the installation and connection of the robot mechanical unit and the control unit, for the purpose of reducing an installation space required for the robot, that the control unit is contained in a support frame on which the robot mechanical unit is placed, a hole for inserting the connecting cable is provided in a bottom surface of the base of the robot mechanical unit, and the connecting cable is passed through the hole so as to electrically connect the internal cables of the mechanical unit with the control unit via a connector arranged inside the base.  
           [0006]    Coupling using a connector on the side of the base arose out of transportation and maintenance considerations. During transportation, the connector at the side of the base is disconnected and the connecting cable is coiled with the control unit so that the robot mechanical unit and the control unit can be transported separately, thus providing ease of transportation. During maintenance as well, by performing the same operation, the control unit can be easily replaced if some malfunction occurs therewith, thus providing ease of maintenance.  
           [0007]    Since robots are usually installed in harsh operating conditions such as factories, the above-described connector for electrically connecting the robot mechanical unit and the control unit must also be highly waterproof so as to be able to withstand such difficult operating environments. In addition, because the connector is exposed, it must be strong enough to not break easily when subjected to external force. Further, it is preferable that the connecting construction of the connecting cable allow easy connection and disconnection. As a result, the connector has become costly and its assembly has come to involve a great number of steps, such as mounting a seal member. Moreover, in order to use the robot installation space efficiently, it is preferable that the connector not take up space unnecessarily by being extended from a rear of the robot base.  
           [0008]    In addition, although installing the control unit inside the support frame of the robot mechanical unit and providing the connector that connects the control unit connecting cable to the internal cables as described in the aforementioned JP 8-1574A eliminates the problem of the connector protruding from the base, the connector still remains as costly as before, and moreover, it is not easy to disconnect the connecting cable from the base of the robot mechanical unit.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides a robot capable of easily connecting and disconnecting a robot mechanical unit and a control unit using an inexpensive connector without being exposed to exterior of the robot mechanical unit.  
           [0010]    A robot of the present invention comprises: a hollow base provided in the robot mechanical unit and having an opening on a lateral surface thereof; a closing member attached to the base so as to cover the opening and having a through-hole or a cutout through which a connecting cable passes; and a connector arranged inside the base for connecting the connecting cable passed through the through-hole or the cutout of the closing member with an internal cable of the robot mechanical unit.  
           [0011]    The connecting cable and the internal cable at opposite sides of the connector may be fixed inside the base.  
           [0012]    Further, the robot may comprise sealing means for sealing a portion of the connecting cable passing through the through-hole or the cutout of the closing member, and may comprise a protective cover for covering the connecter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a diagram showing an overall view of a robot according to one embodiment of the present invention;  
         [0014]    [0014]FIG. 2 a  and  2   b  are diagrams showing a connecting portion between connecting cables and robot mechanical unit-internal cables of one embodiment;  
         [0015]    [0015]FIG. 3 a  and  3   b  are diagrams illustrating mountings and seals, respectively, for the connecting cables of one embodiment;  
         [0016]    [0016]FIG. 4 a  and FIG. 4 b  are diagrams illustrating mountings and seals for the connecting cables according to another embodiment; and  
         [0017]    [0017]FIG. 5 is a diagram showing the structure of a connector assembly that connects the robot mechanical unit-internal cables and the connecting cables in the embodiment shown in FIG. 2 a  and  2   b.   
     
    
     DETAILED DESCRIPTION  
       [0018]    Preferred embodiments of the present invention are now described in detail referring to the accompanying drawings.  
         [0019]    [0019]FIG. 1 is a diagram showing an overall structure of a robot system according to one embodiment of the present invention. A connecting cable  3  extending from inside a control unit  1  is connected through a connector to an internal cable  5  of a robot mechanical unit  2  inside a hollow base  4  of the robot mechanical unit  2 . The internal cable  5  of the robot mechanical unit  2  electrically connects the connecting cable  3  with the individual servomotors for driving joints of the robot mechanical unit  2 , to allow the robot mechanical unit to perform a desired operation by providing operation commands from the control unit  1  to the individual servomotors.  
         [0020]    [0020]FIG. 2 a  and  2   b  are diagrams showing the structure of the connection between connecting cables  3  and the internal cables  5  of the robot mechanical unit. FIG. 2 a  shows a partially sectioned front view of the base  4  and FIG. 2 b  is a side view. A swivel body  7  is mounted in the hollow base  4  of the robot mechanical unit  2  via a speed reducer  6  for revolution. The speed reducer  6  is of hollow construction, and contains the internal cables  5  that electrically connect servomotors M that drive the joints of the robot mechanical unit  2  with the connecting cables  3 , and which are connected to the connecting cables  3  through cable connectors  15  inside the base  4 .  
         [0021]    The internal cables  5  pass through the interior of the robot mechanical unit  2 , that is, the interior of the base  4 , and the interior of the speed reducer  6 , an interior of the swivel body  7  and an interior of a swing arm  10 , and are connected to the servomotors. In addition, the internal cables  5  are fixed in place by a cable clamp  8  inside the base  4  and by a cable clamp  14  inside the swivel body  7  so as to be able to smoothly absorb twisting of the cables as the swivel body  7  revolves, with the inner cable absorbing the twist. An aperture  4   a  is provided in one lateral surface (hereinafter “side”) of the base  4 , with a closing member  11  fixed in place by a bolt or the like so as to cover the aperture  4   a.  Of course, the aperture  4   a  is not a round a hole but rather a staple-shaped opening, one part of which may be an open portion. Further, a cable through-hole  11   a  is also provide on the closing member  11  as well, with a cable mounting member  12  fixedly mounted by stop screws  17  or the like so as to cover the cable through-hole  11   a.  It should be noted that, in FIG. 2 a  and  2   b,  reference numeral  9  designates a speed reducer for the swing arm and reference numeral  16  designates a protective cover that protects the connector  15 .  
         [0022]    The connecting cables  3  connected with the control unit  1  are fed to the base of the robot mechanical unit  2  and through the cable mounting member  12  and the closing member  11  provided with the mounted cable through-hole  11   a  so as to fill the aperture  4   a  in the side of the hollow base  4  from outside the base  4  via the cable through-hole  11   a,  led into the interior of the base  4  and connected to the internal cables  5  by the cable connector.  
         [0023]    The internal cables  5  and the connecting cables  3  that are connected together by the cable connectors  15  are disposed so that the connecting cables  3  are fixed in place by the mounting member  12  fixedly mounted on the closing member  1  via a seal member  13  and the internal cables  5  are fixed in place by the cable clamp  14  inside the base  4 , so that external forces such as a pulling force do not act on the contact of the cable connector  15 . In addition, the cable connector  15 , because it is disposed within the base  4 , is not subjected to unnecessary force from objects other than the robot.  
         [0024]    [0024]FIG. 3 a  and  3   b  are diagrams illustrating the seal member  13  that fixes the connecting cables  3  in place on the mounting member  12  and seals the mounting. FIG. 3 a  is a side view and FIG. 3 b  shows a front view of the mounting member  12 . The connecting cable  3  may be mounted via the seal member  13  on the closing member  11  that is mounted so as to cover the through-hole aperture  4   a  on the side of the base  4 . In the present embodiment, however, the through-hole aperture  4   a  in the side of the base  4  is made large enough to accommodate hands and enable a person to work easily inside the base  4 , and therefore the closing member  11  is also large, and further, the mounting member  12  is provided so that the mounting member  12  can be fixedly mounted on the closing member  11 . The seal member  13  used in the present embodiment is comprised of a rubber mounting  13   a  as an elastic member that clamps the connecting cable  3 , a tube  13   b  that tightens the rubber mounting  13   a,  a nut  13   c  that fixes the tube  13   b  in place on the mounting member  12 , and a tightening member  13   d  that tightens the tube  13   b.  The rubber mounting  13   a  is disposed on the inside of the tube  13   b,  and a screw (not shown) that engages the nut  13   c  and the tightening member  13   d  is disposed on the outside of the tube  13   b.    
         [0025]    The connecting cable  3  is passed through the tube  13   b  with the rubber mounting  13   a  disposed inside, the nut  13   c  and the tightening member  13   d,  and further passed through the through-hole of the mounting member  12 . The tube  13   b,  inside of which is disposed the rubber mounting  13   a,  is then passed through the through-hole of the mounting member  12 , and tightened and fixed in place on the mounting member  12  by the tube  13   b  nut  13   c  from both sides of the mounting member  12 . Further, the tightening member  13   d  is made to engage and compress the tube  13   b  so as to fix the connecting cable  3  in place via the rubber mounting  13   a.  The rubber mounting  13   a  acts as packing between the rubber mounting  13   a  and the connecting cable  3  as well as between the rubber mounting  13   a  and the tube  13   b,  and thus a seal is obtained. In addition, by inserting a gasket at an end face of the nut  13   c,  a seal is obtained between the tube  13   b  and the mounting member  12  as well.  
         [0026]    It should be noted that the above-described seal member is an ordinary one. Provided that the connecting cable  3  can be fixed in place on the mounting member  12  in a sealed state, any commercially available and inexpensive seal material may be used. The foregoing construction enables the operation of connecting the cable connector during installation of the robot to be completed simply by installing the connecting cable mounting as is, thus easing the task of coupling as well as similarly simplifying the task of decoupling.  
         [0027]    [0027]FIG. 4 a  and  4   b  are diagrams showing another embodiment of the mounting of the connecting cables  3  on the mounting member  12 , and of the sealing of the connecting cable mounting. FIG. 4 a  shows a side elevation and FIG. 4 b  shows a front view of the mounting member  12 . Cutouts  12   a  are provided in the mounting member  12  and rubber mountings (elastic bodies)  23   a,  through which the connecting cables  3  have been passed, are inserted into the cutouts  12   a  and fixed in place by wrapping nylon bands  23   b  around the periphery of the rubber mountings  23   a  on both sides of the mounting member  12 , thus fixing the connecting cables  3  and the rubber mountings  23   a  in place on the mounting member  12 . In this case, as the seal member, sponge rubber mountings  23   c  are provided in the cutouts  12   a  in the mounting member  12  to seal the connecting cables  3  and the cutouts  12   a.    
         [0028]    [0028]FIG. 5 is a diagram showing the structure of a connector assembly that connects the connecting cables  3  shown in FIG. 2 a  and  2   b  and the internal cables  5  of the robot mechanical unit  2 . The connector assembly in the present embodiment is comprised of a cable connector  15 . The connecting cables  3  and the internal cables  5  on both ends of the cable connector  15  are fixed in place by the closing member  11  and the cable clamp  14 , respectively, so as to be disposed within the base  4 . The cable connector  15  is enclosed by the base  4 , so external forces do not act directly on the cable connector  15  and thus the arrangement presents no problems in terms of strength, and moreover is safe. As a result, it is not necessary for the connector  15  to be constructed particularly strongly. Moreover, the base  4 , depending on the circumstances of its manufacture, in some cases also has casting holes. Even in these cases, however, because the cable connector  15  is suspended in mid air the cable connector  15  is not directly exposed to dust and water from external sources. Further, when contemplating usage in harsh operating conditions, the protective cover  16  may cover the cable connector  15 . In addition, as another method, a panel mount may be used as the cable connector  15  and the cable connector  15  fixed to a connector mount member  18  fixedly mounted on the base  4 , so as to be able to suspend the cable connector  15  safely in mid air.  
         [0029]    The above-described construction makes it possible to provide high dust resistance without the need for special reinforcement and without the use of an expensive connector. In addition, if the closing member  11  is removed from the base  4 , the connector can be connected and disconnected with ease, providing ease of maintenance of the robot and ease of replacement of the control unit. Moreover, the cable connector  15  is disposed within the base  4 , and thus the connector does not protrude from the rear of the base during connector coupling as in the conventional arrangement, and the amount of space required for installation of the robot can be held to a minimum.  
         [0030]    The present invention enables the coupling of the connecting cables from the control unit and the robot mechanical unit-internal cables to be carried out using an inexpensive construction. Further, the connector assembly is highly dust-proof and coupling and decoupling at the connector assembly is easy, and thus coupling and decoupling of the robot mechanical unit  2  and the control unit can be carried out with ease.