Patent Publication Number: US-2021178611-A1

Title: Housing and joint mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the Japanese Patent Application No. 2019-223358, filed Dec. 11, 2019 the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a housing and a joint mechanism. 
     BACKGROUND 
     An articulated robot apparatus is known as one of industrial machines for performing various assembling and cooperating works. Such an articulated robot apparatus includes a plurality of links and a plurality of joint mechanisms coupling the plurality of links Each joint mechanism is composed of a joint constituting member that pivotably supports a link, a motor for pivoting the link, and a housing that contains components such as a control unit for controlling the motor. The housing of the joint mechanism includes a housing body that has an opening, and a cover to be put over the housing body to close the opening. The cover can be removed to reveal the opening of the housing body and replacement or maintenance can be performed for the motor or the control unit inside the housing body. A gasket is provided to seal between the housing body and the cover to protect the motor, the control unit and the like against dust and moisture. 
     In the joint mechanism of the articulated robot apparatus described above, a cover attachment portion is arranged in one plane and the housing body has a deep box shape. For replacement of parts or maintenance, it is necessary to remove the cover and insert a tool or a hand of an operator into the housing body. Due to the cover attachment portion being in one plane, however, workability is not necessarily satisfactory because the housing body is deep and the opening is small. 
     SUMMARY OF INVENTION 
     Technical Problem 
     There is a need for enlargement of the opening in the housing and the joint mechanism to improve workability for maintenance. 
     Solution to Problem 
     A housing according to one aspect of the disclosure includes: a housing body that contains at least one electromechanical or mechanical component, the housing body including a front plate and a pair of side plates, the plates being connected to a bottom plate in such a manner that the housing body includes an opening; a cover for closing the opening; and a gasket interposed between edge portions of the bottom plate, the front plate, and the pair of side plates of the housing body and an edge portion of the cover to tightly close an inside of the housing body. An edge portion of each of the side plates of the housing body is cut away toward the bottom plate to have a curved shape. 
     According to the aspect, it is possible to enlarge the opening to improve workability for maintenance. 
    
    
     
       BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWING 
         FIG. 1  is a perspective view illustrating a joint mechanism according to a first embodiment. 
         FIG. 2  is an exploded view of a housing in  FIG. 1 . 
         FIG. 3  is a side view of the housing in  FIG. 2 . 
         FIG. 4A  is a partial cutaway view of a sealing structure of the housing in  FIG. 1 . 
         FIG. 4B  is an arrow sectional view of  FIG. 4A . 
         FIG. 5  is a perspective view illustrating a joint mechanism according to the first embodiment. 
         FIG. 6  is an exploded view of the housing in  FIG. 5 . 
         FIG. 7  is a side view of the housing in  FIG. 6 . 
         FIG. 8A  is a partial cutaway view of the sealing structure of the housing in  FIG. 5 . 
         FIG. 8B  is an arrow sectional view of  FIG. 8A . 
         FIG. 9  is a perspective view illustrating a joint mechanism according to a second embodiment. 
         FIG. 10  is an exploded view of a housing in  FIG. 9 . 
         FIG. 11  is a side view of the housing in  FIG. 10 . 
         FIG. 12A  is a perspective view of a joint mechanism according to a third embodiment. 
         FIG. 12B  is an arrow view of  FIG. 12A . 
         FIG. 13  is an exploded view of a housing in  FIG. 12A . 
         FIG. 14A  is a right side view of the housing in  FIG. 13 . 
         FIG. 14B  is a left side view of the housing in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION 
     A joint mechanism and a housing thereof according to an embodiment will now be described with reference to drawings. In the description below, components that have substantially like functions and configurations will have like reference characters and the description will be repeated only as necessary. 
     A housing according to the embodiment contains at least one electromechanical or mechanical component and is applied in various uses. Description will now be made here as to an instance in which the housing is applied to a joint mechanism coupling links of an articulated robot. 
     First Embodiment 
     As illustrated in  FIGS. 1 to 3 , a joint mechanism  100  according to a first embodiment includes joint constituting members  130 ,  140  such as bearings, each of which is a mechanical component, a motor  150  as an electromechanical component, and a housing  101 . The housing  101  consists of a housing body  110 , part of which is open and which is made of metal, and a cover  120  that is made of metal or resin and put over the housing body  110  to close an opening K. 
     The housing body  110  typically includes a rectangular bottom plate (also referred to as a base plate)  111 . A front plate  115  and a pair of side plates  112 ,  113  are connected to the bottom plate  111 . The pair of side plates  112 ,  113  each have a shape similar to a trapezoid, one of interior angles of which is a right angle or a near right angle. Here, edge portions Ka of the side plates  112 ,  113  each corresponding to an oblique line of the trapezoid is not linear and is formed in a curved shape, or preferably an arcuate shape, which is cut away toward the bottom plate  111  in a large concave shape. In this way, when the cover  120  is removed, the motor  150 , which is an electromechanical component, and joint constituting members  130 ,  140 , which are mechanical components, are exposed largely from the opening K of the housing body  110 , so that access to the components is facilitated. 
     A narrow strip-shaped top plate  114  is connected to the pair of side plates  112 ,  113  and the front plate  115 . In this way, the housing body  110  has a rectangular-parallelepiped shape (a box shape), one face of which is open, and which thus consists of five faces. Since the front plate  115  and the pair of side plates  112 ,  113  are connected to three sides of the bottom plate  111  and the front plate  115 , and the pair of side plates  112 ,  113  are connected together by the top plate  114 , more rigidity of the housing body  110  as a boxy body can be secured than the case in which no top plate  114  is provided. Further, the opening K can be made larger than an opening in the case in which the pair of side plates are rectangular or the case in which edge portions Ka of the side plates are linear. 
     The joint constituting member  140  such as a bearing, which is a mechanical component and rotatably supports a link, is attached to the front plate  115 . The joint constituting member  130  such as a bearing that rotatably supports another link, and the motor  150  as an electromechanical component is attached to the bottom plate  111 . 
     The cover  120  has a shape that matches with the opening K of the housing body  110  and the edge portions Ka. A rear end plate  121 , a pair of side plates  122 ,  123 , and a top plate  124  are connected to a rectangular and planar oblique plate  125 . Edge portions Kb of the pair of side plates  122 ,  123  each have a curved convex shape that matches with the respective edge portions Ka of the pair of side plates  112 ,  113  of the housing body  110 . 
     An endless gasket  160  is interposed between the edge portions Ka of the bottom plate  111 , the top plate  114 , and the pair of side plates  112 ,  113  of the housing body  110  and the edge portions Kb of the rear end plate  121 , the pair of side plates  122 ,  123 , and the top plate  124  of the cover  120  to secure air tightness inside the housing  101 . The gasket  160  is typically cut out from a planar sheet and formed into a flat endless shape that has a fixed thickness. 
       FIG. 4A  illustrates a partial cutaway view of the housing  101  and  FIG. 4B  illustrates an arrow sectional view of  FIG. 4A . Steps are provided in the edge portions Ka of the housing body  110  and the edge portions Kb of the cover  120  along the thickness direction so as to face outward in such a manner that a gap that has a predetermined width is created while the edge portions Ka of the housing body  110  are in contact with the edge portions Kb of the cover  120 . With the steps, endless grooves  112   a ,  112   b  are created in the edge portions Ka of the housing body  110  and the edge portions Kb of the cover  120 , respectively, along the edge direction on the outside from a screw  127 . Note that a groove may be provided only in one of the edge portion Ka of the housing body  110  and the edge portion Kb of the cover  120 , and the other may be flat. 
     A gasket  160  is fit into the grooves  112   a ,  112   b  as an endless elastic member (rubber member). In a steady state in which the gasket  160  is not subjected to an external pressure, the thickness of the gasket  160  is slightly larger than the total of the depth of the groove  112   a  and the depth of the groove  112   b . When the cover  120  is brought into close contact with the housing body  110 , the gasket  160  is compressed in the thickness direction and press fit between the grooves  112   a  and  112   b , so that sealability is secured by its restoring force. 
     Linear grooves  128  through which a screw driver (not illustrated) or a screw  127  is passed along its plane direction is formed in, for example, 6 locations: where the rear end plate  121  of the cover  120  and the pair of side plates  122 ,  123  are joined; where the top plate  124  and the pair of side plates  122 ,  123  are joined; the midpoint of the rear end plate  121 ; and the midpoint of the top plate  124 , and a flange  122   c  provided with a screw through hole  112   c  is provided in the bottom of the linear groove  128 . A threaded screw hole  112   d  is formed in the edge portion Ka of the housing body  110  opposite to the screw through hole  112   c . Fastening the screw  127  into the screw hole  112   d  brings the edge portions Ka and Kb into close contact with each other and compresses the gasket  160 . In this way, the housing body  110  and the cover  120  are joined air-tight on their outside via the gasket  160 , and the edge portions Ka and Kb are in direct contact with each other on the inside from the screw  127 . 
     When the housing body  110  and the cover  120  are both formed of metal, metal touch is achieved inside and air tightness is secured outside by the gasket  160 . In this structure, a side surface of the gasket  160  is exposed to the external environment to avoid metal-touch part connection, which is unacceptable for food manufacturing lines, as much as possible, so that it is possible to prevent bacteria or the like from propagating in the gap. More preferably, the screw  127  is inserted in a rubber bush. In this way, metal-touch part connection between the screw  127  and the flange  122   c  is also avoided. Accordingly, the articulated robot can be used for food manufacturing lines. 
     As described above, by cutting away edge portions Ka of the pair of side plates  112 ,  113  in a curved concave shape, it is possible to enlarge the opening K in the housing body  110 . When the cover  120  is removed, the electromechanical or mechanical component contained in or attached to the housing body  110  can be largely exposed. In this way, during replacement of parts or maintenance, a tool or a hand of an operator can easily be inserted and thus working efficiency can be improved. 
     Since the edge portions Ka of the housing body  110  and the edge portions Kb of the cover  120  are curved in such a manner that the edge portions match with each other, the housing body  110  and the cover  120  can easily be aligned, and misalignment or a gap is less likely to occur. Working efficiency for fastening screws or the like is also improved. 
     In the case in which the articulated robot apparatus is not used for food manufacturing lines, the material of the cover  120  is relatively arbitrary. For example, the weight of the joint mechanism  100  can be reduced when the housing body  110  is made of metal to maintain the strength and the cover  120  is made of resin material. The weight reduction of the joint mechanism  100  allows reduction in strength of portions of the articulated robot or output power of motors, which contributes to downsizing and energy saving. 
     Since the front plate  115  and the pair of side plates  112 ,  113  are connected to three sides of the bottom plate  111 , and the front plate  115  and the pair of side plates  112 ,  113  are connected with the top plate  114 , it is possible to secure rigidity of the housing body  110  as a boxy body. 
     In the above described structure, the screw  127  is arranged inside and the gasket  160  is arranged outside. However, as illustrated in  FIGS. 5 to 8B , the screw  127  may be arranged outside and the gasket  160  may be arranged inside in another structure. In such a structure, the edge portions Ka of the housing body  110  and the edge portions Kb of the cover  120  constitute metal touch with respect to the external environment, which is however sealed by the gasket  160  at the innermost. Depending on uses of the articulated robot, such a structure may be preferable. 
     Second Embodiment 
       FIGS. 9 to 11  illustrate a joint mechanism according to a second embodiment. In the structure in the first embodiment, the edge portions Ka of the side plates  112 ,  113  of the housing body  110  are cut away toward the bottom plate  111  in a large arcuate shape. In the embodiment, since a joint constituting member  230  is attached to a side plate  212  of a housing body  210 , such a structure, in which an edge portion Ka of the side plate  212  is cut away toward a bottom plate  211  in a large arcuate shape, cannot be adopted. However, to enlarge the opening K of a housing body  210  when a cover  220  of the housing body  210  is removed, a structure as described below is provided. A detailed description will be as follows. 
     A housing  201  of a joint mechanism  200  consists of a housing body  210  and a cover  220 , and the housing body  210  includes a rectangular bottom plate  211 . A front plate  215  and a pair of side plates  212 ,  213  are connected to three sides of the bottom plate  211 . A joint constituting member  270  such as a bearing, which is a mechanical component, and a motor  250  as an electromechanical component are attached to the bottom plate  211 . A joint constituting member  240  is attached to the front plate  215 , and additionally a joint constituting member  230  is attached to the side plate  212 . 
     The edge portion Ka of the side plate  212  is not linear and has a curved, and not acute, shape along the outline of the joint constituting member  230  attached to the side plate  212  in such a manner that the joint constituting member is surrounded. 
     The cover  220  has a shape that matches with the opening K of the housing body  210  and the edge portions Ka. A rear end plate  221 , a pair of side plates  222 ,  223 , and a top plate  224  are connected to a rectangular and planar oblique plate  225 . Edge portions Kb of the pair of side plates  222 ,  223  has a curved concave shape that matches with the edge portions Ka of the pair of side plates  212 ,  213  of the housing body  210 . 
     An endless gasket  260  is interposed between the edge portions Ka of the bottom plate  211 , the top plate  214 , and the pair of side plates  212 ,  213  of the housing body  210  and the edge portions Kb of the rear end plate  221 , the pair of side plates  222 ,  223 , and the top plate  224  of the cover  220  to secure air tightness inside the housing  201 . 
     The sealing structure by means of a gasket  260  and the connecting structure are similar to those of the first embodiment. Grooves are endlessly formed in the edge portions Ka of the housing body  210  and the edge portions Kb of the cover  220 , respectively, along the edge direction on the inside or outside from the screw  227  in such a manner that a gap that has a predetermined width is created while the edge portions Ka of the housing body  210  are in contact with the edge portions Kb of cover  220 . The gasket  260  that is an endless elastic member (made of rubber) is fit between the grooves. In an unloaded steady state, the thickness of the gasket  260  is slightly larger than the total depth of the grooves. When the housing body  210  is in close contact with the cover  220 , the gasket  260  is compressed in the thickness direction and press fit between the grooves, so that sealability is secured by its restoring force. 
     Linear grooves  228  through which a screw driver (not illustrated) or a screw  227  is passed along its plane direction is formed on opposite sides and in the center of both the rear end plate  221  and the top plate  224  of the cover  220 . The screw  227  is inserted through a screw through hole in a flange in the bottom of the linear groove  228  and fastened in a screw hole in the edge portions Ka of the opposing housing body  210 . In this way, the edge portions Ka and Kb are brought into close contact with each other and the gasket  260  is compressed. The housing body  210  and the cover  220  are joined air-tight via the gasket  260 , and the edge portions Ka and Kb are in direct contact with each other on the inside or outside from the screw  227 . 
     In the embodiment, as with the first embodiment, the opening K of the housing body  210  can be enlarged to largely expose the electromechanical or mechanical component, so that workability can be improved for replacement of parts or maintenance. The housing body  210  and the cover  220  can easily be aligned, and misalignment or a gap is less likely to occur. Working efficiency for fastening screws or the like is also improved. Other similar effects to the first embodiment may be produced. 
     Third Embodiment 
       FIGS. 12A to 14B  illustrate a joint mechanism according to a third embodiment. In the structure in the first embodiment, the edge portions Ka of the side plates  112 ,  113  of the housing body  110  are cut away toward the bottom plate  111  in a large arcuate shape. In the embodiment, since a joint constituting member  330  is attached to a side plate  312  of a housing body  310 , such a structure, in which an edge portion Ka of the side plate  312  is cut away toward a bottom plate  311  in a large arcuate shape, cannot be adopted. However, to enlarge the opening K of a housing body  310  when a cover  320  of the housing body  310  is removed, a structure as described below is provided. A detailed description will be as follows. 
     A housing  301  of a joint mechanism  300  consists of a housing body  310  and a cover  320 , and the housing body  310  includes a rectangular bottom plate  311 . A front plate  315  and a pair of side plates  312 ,  313  are connected to three sides of the bottom plate  311 . A narrow strip-shaped top plate  314  is connected to the top sides of the pair of side plates  312 ,  313 . A joint constituting member  370  such as a bearing, which is a mechanical component, and a motor  350  as an electromechanical component are attached to the bottom plate  311 . A joint constituting member  340  is attached to the front plate  315 , and additionally a joint constituting member  330  is attached to the side plate  312 . No joint constituting member, electrical component such as a motor, nor mechanical component is attached to the other side plate  313 . An edge portion Ka′ of the side plate  313  is cut away toward the bottom plate  311  in a large arcuate shape, as with the side plate  113  in the first embodiment. 
     An edge portion Ka of the side plate  312  is not linear and is shaped such that a curved convex-shaped portion Ka 1  protruding along the outline of the joint constituting member  330  attached to the side plate  312  in such a manner that the joint constituting member is surrounded is continuously connected to cut-away curved concave-shaped portions Ka 2 , Ka 3  on opposite sides of the portion Ka 1 . 
     The cover  320  has a shape that matches with the opening K of the housing body  310  and the entire edge portions. A rear end plate  321 , a pair of side plates  322 ,  323 , and a top plate  324  are connected to a rectangular and planar oblique plate  325 . Edge portions Kb, Kb′ of the pair of side plates  322 ,  323  have the respective curved shapes that match with the edge portions Ka, Ka′ of the pair of side plates  312 ,  313  of the housing body  310 . 
     An endless gasket  360  is interposed between the entire edge portions of the bottom plate  311 , the top plate  314 , and the pair of side plates  312 ,  313  of the housing body  310  and the entire edge portions of the rear end plate  321 , the pair of side plates  322 ,  323 , and the top plate  324  of the cover  320  to secure air tightness inside the housing  301 . 
     The sealing structure by means of a gasket  360  and the connecting structure are similar to those of the first embodiment. Grooves are endlessly formed in the edge portions Ka of the housing body  310  and the edge portions Kb of the cover  320 , respectively, along the edge direction on the inside or outside from the screw  327  in such a manner that a gap that has a predetermined width is created while the edge portions of the housing body  310  are in contact with the edge portions of cover  320 . The gasket  360  that is an endless elastic member (made of rubber) is fit between the grooves. In an unloaded steady state, the thickness of the gasket  360  is slightly larger than the total depth of the grooves. When the housing body  310  is in close contact with the cover  320 , the gasket  360  is compressed in the thickness direction and press fit between the grooves, so that sealability is secured by its restoring force. 
     Linear grooves  328  through which a screw driver (not illustrated) or a screw  327  is passed along its plane direction is formed on opposite sides and in the center of both the rear end plate  321  and the top plate  324  of the cover  320 . The screw  327  is inserted through a screw through hole in a flange in the bottom of the linear groove  328  and fastened in a screw hole in the edge portions Ka of the opposing housing body  310 . In this way, the edge portions Ka and Kb are brought into close contact with each other and the gasket  360  is compressed. The housing body  310  and the cover  320  are joined air-tight via the gasket  360 , and the edge portions Ka and Kb are in direct contact with each other on the inside or outside from the screw  327 . The lengths of Ka and Ka′ may be the same as each other to allow the gasket  360  to lie flat. 
     In the embodiment, as with the first embodiment, the opening K of the housing body  310  can be enlarged to largely expose the electromechanical or mechanical component, so that workability can be improved for replacement of parts or maintenance. The housing body  310  and the cover  320  can easily be aligned, and misalignment or a gap is less likely to occur. Working efficiency for fastening screws or the like is also improved. In addition, similar effects to the first embodiment may be produced, such as an ability to secure rigidity of the housing body  310  as a boxy body. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.