Patent Publication Number: US-2023138172-A1

Title: Electric chain block

Description:
TECHNICAL FIELD 
     The present invention relates to an electric chain block. 
     BACKGROUND ART 
     In an electric chain block which lifts and lowers a load using the driving force of a motor, the load can be lifted and lowered by making a load chain get in/out though an inlet/outlet (hereinafter, referred to as a chain inlet/outlet) at a bottom surface of a body part. The chain inlet/outlet is provided in a cross shape when the chain inlet/outlet is viewed in plan view by a longitudinal groove and a lateral groove orthogonal to each other. 
     Incidentally, when the load chain is pulled into the inside of the body part  20  through the cross-shaped chain inlet/outlet, the direction of a link is adjusted at a stage before the link reaches the chain inlet/outlet in a state where the tension to the load chain acts in a vertical direction (for example, when the body part is suspended). Thus, the load chain can smoothly get in/out without jamming (getting stuck) near the chain inlet/outlet. However, in a state where no tension is applied to the load chain, especially, as in the case where the body part is placed on the floor, each of links constituting the load chain reaches the chain inlet/outlet in a state where each link is irregular in orientation. For this reason, the load chain may get stuck near the chain inlet/outlet. 
     Examples of the technique for preventing the load chain from getting stuck near the chain inlet/outlet as explained above include those disclosed in Patent Literature 1 to Patent Literature 3. In Patent Literature 1, a prismatic body (d) projecting from a bottom surface part is provided, and the prismatic body (d) separates a third link ( 3 ) which has already entered a cross groove, from the bottom surface. This prevents a head portion of the third link ( 3 ) from running into the groove, so that when a first link ( 1 ; a link entered the cross groove) is pulled in, a second link ( 2 ) is slightly rotated and, accompanying the rotation, the third link ( 3 ) can also be rotated to prevent the load chain from getting stuck. 
     Further, in the configuration disclosed in Patent Literature 2, an arc surface ( 9 ) is provided at an opening end portion of a chain inlet/outlet in a manner to cope with a case where a load chain is pulled into a cross-shaped groove from an oblique direction, so as to untangle links. In addition to this, depths on one side and the other side of a lateral link through hole ( 8 ) are varied. 
     In the configuration disclosed in Patent Literature 2, a certain type of being stuck can be released. More specifically, a longitudinal groove and a lateral groove of the chain inlet/outlet correspond to a length in a short side direction of an oval-shaped link. Accordingly, when the link becomes, in a long side direction, a bridging state of blocking the longitudinal groove or the lateral groove at a normal chain inlet/outlet, the load chain easily gets stuck, whereas the link enters, in an inclining state, the longitudinal groove or the lateral groove because of the presence of a depth B and a depth C in the configuration disclosed in Patent Literature 1. For this reason, when the link is pulled in, the link easily rotates to be able to release the load chain from being stuck. 
     Further, in a configuration disclosed in Patent Literature 3, an area near a chain inlet/outlet bulges more than the other bottom surface, and an inclined portion which becomes wider as going toward an opening is formed in a longitudinal groove and a lateral groove. This enables a link located on a top portion side of the bulging portion to rotate when pulling in the load chain, thereby preventing the load chain from getting stuck. 
     CITATION LIST 
     Patent Literature 
     
         
         {PTL 1} JP S45-36625 A 
         {PTL 2} JP S49-41780 A 
         {PTL 3} EP 2931650 B1 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     Incidentally, when the motor continues to drive in a state where a lower hook collides with the bottom surface, the body part, the motor or the like may be damaged. Accordingly, it is necessary to detect that the lower hook collides with the bottom surface of the body part and, as one of means for detection, a press-type limit switch may be provided. 
     However, in the configurations disclosed in Patent Literature 1 to Patent Literature 3, the area near the chain inlet/outlet projects more than the bottom surface of the body part. For this reason, the limit switch cannot be pressed, or a need to add a separate member for the press arises. 
     Further, in the configuration disclosed in Patent Literature 2, when the link, in a rising state, enters the lateral groove or the longitudinal groove, it is possible to release the load chain from being stuck as explained above. However, the longitudinal groove and the lateral groove of the chain inlet/outlet have only a groove width corresponding to the diameter of the link. For this reason, the link does not completely rise but gets into a state of inclining sideways or tilting, and cannot release the load chain from being stuck depending on the position of a subsequent link. 
     The present invention has been made in consideration of the above circumstances, and has an object to provide an electric chain block in which it can be solved at least one of that a limit switch can be pressed by a lower hook colliding with a body part and that even if a link falls sideways or inclines, the link can easily enter a chain inlet/outlet. 
     Solution to Problem 
     To solve the above problem, according to a first aspect of the present invention, an electric chain block for hoisting or lowering a load chain coupled to a lower hook by rotating a load sheave by driving of a motor, the electric chain block includes: a body part including the motor and the load sheave; and a chain inlet/outlet which is provided at a bottom surface of the body part and through which the load chain on a load side gets in/out, wherein the chain inlet/outlet includes: a first guide groove which is provided on an opening side of the chain inlet/outlet, and includes a first longitudinal groove and a first lateral groove which have a groove length corresponding to a length in a long side direction of each link of the load chain, the first longitudinal groove and the first lateral groove orthogonally crossing each other; and a second guide groove which is provided on a side deeper in the body part than the first guide groove is, and includes a second longitudinal groove and a second lateral groove which have a groove length corresponding to a length in a short side direction of each link of the load chain, the second longitudinal groove and the second lateral groove orthogonally crossing each other, the first guide groove including: narrowed parts which face each other across a groove width corresponding to a wire diameter of the link of the load chain in a width direction of the first longitudinal groove and face each other across the groove width in a width direction of the first lateral groove to determine into which of the first longitudinal groove and the first lateral groove each link of the load chain is introduced when the link is pulled in; and expanded groove parts which are provided on an outside further away from a center of the chain inlet/outlet than the narrowed parts are, and have a width larger than the groove width. 
     Further, in the above embodiment, it is preferable that the first longitudinal groove and the first lateral groove are formed at a depth where the link to be pulled into the first longitudinal groove or the first lateral groove reaches an inside of the second guide groove and is rotatable in a manner to fall down using the link in contact with the bottom surface as a fulcrum. 
     Further, in the above embodiment, it is preferable that the narrowed parts are provided in a manner to be flush with the bottom surface and to continue into the bottom surface. 
     Further, in the above embodiment, it is preferable that at least a part of a pressed part of a limit switch is arranged to project in a space located in a range where a base part of the lower hook collides with the bottom surface near the chain inlet/outlet; and the pressed part is pressed to stop the driving of the motor. 
     Advantageous Effects of Invention 
     According to the present invention, an electric chain block can be provided in which a limit switch can be pressed by a lower hook colliding with a body part, and even if a link falls sideways or inclines, the link can easily enter a chain inlet/outlet. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view illustrating a configuration of an electric chain block according to a first embodiment of the present invention. 
         FIG.  2    is a perspective view illustrating a state of an inverted suspension in the electric chain block illustrated in  FIG.  1   . 
         FIG.  3    is a cross-sectional view illustrating a configuration near a load sheave of the electric chain block illustrated in  FIG.  1   . 
         FIG.  4    is a perspective view illustrating configurations of the load sheave, an arc-shaped covering member, and a limit switch around a guide member of a body of the electric chain block illustrated in  FIG.  1   . 
         FIG.  5    is a partial perspective view illustrating a configuration near a chain inlet/outlet of the body part of the electric chain block illustrated in  FIG.  1   . 
         FIG.  6    is a plan view illustrating the configuration near the chain inlet/outlet of the body part of the electric chain block illustrated in  FIG.  1   . 
         FIG.  7    is a cross-sectional view illustrating the configuration near the chain inlet/outlet of the body part of the electric chain block illustrated in  FIG.  1   , and a view illustrating a state cut along a first lateral groove. 
         FIG.  8    is a plan view illustrating a link used in the electric chain block in  FIG.  1   . 
         FIG.  9    is a view illustrating an example in which a load chain gets stuck around a current chain inlet/outlet. 
         FIG.  10    is a view illustrating an image where the load chain is released from being stuck around the chain inlet/outlet owing to the presence of an expanded groove part in the electric chain block illustrated in  FIG.  1   . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an electric chain block  10  according to an embodiment of the present invention will be explained with reference to the drawings. Note that in the following explanation, a Z-direction represents a direction in which a load chain C 1  is suspended, and a Z 1  side represents a side where an upper hook  70  is located and a Z 2  side represents a side opposite thereto where a lower hook  80  is located. Accordingly, the Z 1  side represents the upper side and the Z 2  side represents the lower side in a normal suspension, whereas the Z 1  side represents the lower side and the Z 2  side represents the upper side in an inverted suspension. However, in this description, the Z 1  side represents the upper side and the Z 2  side represents the lower side unless otherwise stated. 
     Further, an X-direction represents a long side direction of a body part  20 , and an X 1  side represents an upper right side in  FIG.  1    and an X 2  side represents a lower left side opposite thereto. Further, a Y-direction represents a direction orthogonal to the Z-direction and to the X-direction, and a Y 1  side represents a right side in  FIG.  1    and a Y 2  side represents a left side opposite thereto. 
     &lt;Regarding the Overall Configuration of the Chain Block&gt; 
       FIG.  1    is a perspective view illustrating a configuration of the electric chain block  10  according to an embodiment of the present invention.  FIG.  2    is a perspective view illustrating a state of the inverted suspension in the electric chain block  10  illustrated in  FIG.  1   .  FIG.  3    is a cross-sectional view illustrating the configuration near a load sheave  22  of the electric chain block  10  illustrated in  FIG.  1   . As illustrated in  FIG.  1   , the electric chain block  10  includes the body part  20 , the upper hook  70 , the lower hook  80 , a chain bucket  90 , and a bucket attachment bracket  100 . Further, as illustrated in  FIG.  1    and  FIG.  2   , the electric chain block  10  in this embodiment is a type capable of realizing both the normal suspension and the inverted suspension. 
     &lt;Regarding the Body Part  20 &gt; 
     The body part  20  has a body  30 , a motor  40 , a load sheave  50 , and a guide member  60  as primary components. Among them, the body  30  and the guide member  60  are integrally fixed by bolts or the like to constitute one housing. 
     &lt;Regarding the Body  30 &gt; 
     The body  30  is formed of, for example, an aluminum-based metal or an iron-based metal as a material. As illustrated in  FIG.  3   , the body  30  has a portion which forms an outer surface such as a side surface  31  and a top surface  32 , and a structure portion present inside the outer surface. Further, though the body  30  is dented from the outer surface at a section to which the later-explained guide member  60  is to be attached, the body part  20  is configured in a state almost without dent when the guide member  60  is attached to the body  30 . 
     Inside the body  30 , the motor  40  and the load sheave  50  are provided in a state of not being exposed to the outside. Further, to the body  30 , the guide member  60  for guiding feed of the load chain C 1  is also attached. The guide member  60  is a separate component from the body  21  in the configuration illustrated in  FIG.  3   , but the guide member  60  may be integrated with the body  30  (may be the same component as the body  30 ). Note that the details of the configuration of the guide member  60  will be explained later. 
     &lt;Regarding the Motor  40  and the Load Sheave  50 &gt; 
     Further, inside the body  30 , the driving force from the motor  40  is transmitted to the load sheave  50 . The load sheave  50  includes a plurality of chain pockets  51 , and a metal ring of the load chain C 1  can fit into the chain pockets  51 . Accordingly, driving of the motor  40  enables hoisting or lowering of the load chain C 1 . 
     &lt;Regarding the Upper Hook  70  and a Link Shaft S 1 &gt; 
     Further, to the body  30 , the upper hook  70  is attached via a link shaft S 1  inserted into a shaft hole  34  of the body  30 . The upper hook  70  includes a hook part  71  and a hook receiving part  72 . The hook part  71  is a portion on which a baggage, a ceiling or the like is hung. Further, the hook receiving part  72  is a portion which rotatably supports the hook part  71 . The hook receiving part  72  is provided with an attachment hole  72   a  which penetrates the hook receiving part  72  in the Y-direction. Into the attachment hole  72   a , the link shaft S 1  is inserted. Thus, the upper hook  70  is supported by the body part  20  (body  30 ) via the link shaft S 1 . 
     &lt;Regarding the Lower Hook  80 &gt; 
     The lower hook  80  includes a base part  81 , and the base part  81  is coupled to a lower end side (Z 2  side) of the load chain C 1  fed from a chain inlet/outlet  611  (later explained) of a first guide passage  610  of the guide member  60 . Further, the lower hook  80  includes a hook part  82  on which a baggage is hung, and the hook part  82  is attached, in a rotatable manner, to the base part  81 . The lower hook  80  collides with a bottom surface  33  of the body  30  and, at that time, presses a later-explained limit switch  120 . This can stop the driving of the motor  40  and thereby stop the hoisting of the lower hook  80 . 
     &lt;Regarding the Chain Bucket  90 &gt; 
     As illustrated in  FIG.  1   , the chain bucket  90  is a bucket-shaped portion for housing the load chain C 1  discharged from a later-explained side surface chain inlet/outlet  651 . The chain bucket  90  is formed of resin or cloth, as a material, which has flexibility while sufficiently bearing the weight of the load chain C 1 . The chain bucket  90  is attached to the bucket attachment bracket  100  via a coupling tool  110  such as a carabiner, a wire, or another. Therefore, the chain bucket  90  is in a state of being attached to the body part  20  (the body  30  and the guide member  60 ) via the coupling tool  110  and the bucket attachment bracket  100 . 
     &lt;Regarding the Bucket Attachment Bracket  100 &gt; 
     As illustrated in  FIG.  1    to  FIG.  3   , the bucket attachment bracket  100  has a bucket attachment part  105 . The bucket attachment part  105  is a portion to which the chain bucket  90  is attached via the coupling tool  110 . In this embodiment, the bucket attachment part  105  includes an attachment arm  105   a  in an almost U-shape projecting from the side surface  31  side, and an insertion section of the coupling tool  110  can be inserted into an attachment hole  105   b  surrounded by the attachment arm  105   a.    
     Note that the attachment hole  105   b  has a predetermined length along the Z-direction (namely, being in a long-hole shape along the Z-direction). Further, in the normal suspension, the coupling tool  110  is located on the Z 2  side (lower side) of the attachment hole  105   b  and the chain bucket  90  can be attached via the coupling tool  110 . On the other hand, in the inverted suspension, the coupling tool  110  is located on the Z 1  side (upper side in the normal suspension) of the attachment hole  105   b  and the chain bucket  90  can be attached via the coupling tool  110 . Accordingly, in both cases of the normal suspension and the inverted suspension, the load chain C 1  hanging down due to the self weight can be well housed in the chain bucket  90 . 
     &lt;Regarding the Guide Member  60  and the Limit Switch  120 &gt; 
     The guide member  60  constitutes, together with the above-explained body  30 , a structure portion of the body part  20 . As illustrated in  FIG.  3   , the guide member  60  is provided in a manner to be close to the load sheave  50  at predetermined positions (a first position and a second position). Thus, the load chain C 1  is fed out while well fitting into the chain pocket  51  located in a prescribed angle range in the body  30 . Note that the guide member  60  is composed of a block body of metal having abrasion resistance and having strength, such as carbon steel, alloy steel, or the like. 
       FIG.  4    is a perspective view illustrating configurations of the load sheave  50 , an arc-shaped covering member  67 , and the limit switch  120  around the guide member  60 . As illustrated in  FIG.  3    and  FIG.  4   , the guide member  60  is provided with the first guide passage  610  and a second guide passage  650 . The first guide passage  610  is a portion which well guides the movement of the load chain C 1  extending toward the lower hook  80  side (Z 2  side). Note that a side of the first guide passage  610  where the load chain C 1  gets in/out is called the chain inlet/outlet  611 , and a side of the second guide passage  650  where the load chain C 1  gets in/out is called the side surface chain inlet/outlet  651 . 
       FIG.  5    is a partial perspective view illustrating a configuration near the chain inlet/outlet  611  of the body part  20 .  FIG.  6    is a plan view illustrating the configuration near the chain inlet/outlet  611  of the body part  20 .  FIG.  7    is a cross-sectional view illustrating the configuration near the chain inlet/outlet  611  of the body part  20 , and a view illustrating the state cut along a first lateral groove. 
     As illustrated in  FIG.  5    to  FIG.  7   , the chain inlet/outlet  611  is provided with a first guide groove  620  and a second guide groove  630 . More specifically, the first guide groove  620  is a portion which is provided on a side closer to an opening of the chain inlet/outlet  611  than the second guide groove  630  is. In other words, the first guide groove  620  and the second guide groove  630  are continuous, and the first guide groove  620  of them is present on the opening side of the chain inlet/outlet  611  and the second guide groove  630  is present on a side deeper in the body part  20  than the first guide groove  620  is. 
     The first guide groove  620  is provided with a first longitudinal groove  621  and a first lateral groove  622  which orthogonally cross each other (namely, the first longitudinal groove  621  and the first lateral groove  622  are provided in a cross-shape). A length L1 of the first longitudinal groove  621  and the first lateral groove  622  is made to correspond to a length in a long side direction of each link C 1   a  of the load chain C 1 .  FIG.  8    is a plan view illustrating the link C 1   a . As illustrated in  FIG.  8   , when the length in the long side direction of the link C 1   a  is M 1 , the first longitudinal groove  621  and the first lateral groove  622  are provided to have the length L1 which is larger than the length M 1 . 
     Note that when it is assumed that a dimension in the long side direction of an inner hole of the link C 1   a  is P, a groove width of the first longitudinal groove  621  and the first lateral groove  622  is L2, and a diameter of the link C 1   a  is d, it is preferable that the length L1 of the first longitudinal groove  621  and the first lateral groove  622  is set to the following (Expression 1). 
         L 1=( P−d+L 2/2)×2  (Expression 1)
 
     Note that when it is assumed that the first longitudinal groove  621  is along an axial direction (X-direction) of the load sheave  50 , it is preferable that the groove width L2 of the first longitudinal groove  621  (referred to as a groove width L21) is larger than the groove width L2 of the first lateral groove  622  (referred to as a groove width L22). This is because a line linking the chain pockets  51  of the load sheave  50  is a polygon and the link C 1   a  therefore slightly swings (vibrates) in the Y-direction with the rotation of the load sheave  50 . 
     Further, the first longitudinal groove  621  and the first lateral groove  622  are provided with a narrowed part  623 . The narrowed part  623  is a portion which faces the first longitudinal groove  621  and the first lateral groove  622 , and four narrowed parts  623  are provided as illustrated in  FIG.  6   . The narrowed part  623  is provided with a tip part  623   a  and a plane part  623   b . The tip part  623   a  of them is provided to be smaller in curvature radius than a corner portion of a later-explained expanded groove part  624  in order to limit the orientation of the link C 1   a . The curvature radius is preferably provided to be a curvature radius at the same level as that of the narrowed part at a current chain inlet/outlet. 
     Setting the curvature radius of the tip part  623   a  not to be larger than that of the expanded groove part  624  but to be the same level as the curvature radius of the narrowed part at the current chain inlet/outlet as explained above, makes it possible to adjust the direction of the link C 1   a  entered the first longitudinal groove  621  or the first lateral groove  622  so as to be along either the first longitudinal groove  621  or the first lateral groove  622 . This prevents the link C 1   a  from entering the inside of the first longitudinal groove  621  or the first lateral groove  622 , in a state of not being adjusted in the direction of either the first longitudinal groove  621  or the first lateral groove  622 , thereby preventing failure of hoisting with the load sheave  50 . 
     Further, the plane part  623   b  is a portion which is provided in parallel with the long side direction of the first longitudinal groove  621  or the first lateral groove  622 . Two plane parts  623   b  at each narrowed part  623  are provided to orthogonally cross each other. The plane part  623   b  has a predetermined length and thereby prevents the tip part  623   a  from being abraded in a short time. Further, the interval between the plane parts  623   b  facing each other corresponds to the groove width L2 of the first longitudinal groove  621  or the first lateral groove  622 . 
     Note that in this embodiment, the narrowed parts  623  are provided to be flush with the bottom surface  33 . This improves the abrasion resistance of the narrowed parts  623 . 
     Further, the first longitudinal groove  621  and the first lateral groove  622  are also provided with the expanded groove parts  624 . The expanded groove parts  624  are portions of the first longitudinal groove  621  and the first lateral groove  622  which are expanded in groove width so as to have an interval larger than that of the groove width L2 at sections on sides closer to ends in the groove direction than the narrowed parts  623 . Further, because of the presence of the expanded groove parts  624 , the groove length of the first longitudinal groove  621  and the first lateral groove  622  is elongated to the groove length L1. In other words, because of the presence of the expanded groove parts  624  in the first longitudinal groove  621  and the first lateral groove  622 , the groove length L1 of the first longitudinal groove  621  and the first lateral groove  622  is larger than the groove length of the second longitudinal groove  631  and the second lateral groove  632  of the later-explained second guide groove  630 . 
     The expanded groove part  624  is a portion for allowing a leading portion of the link C 1   a  in a state of slightly inclining with respect to the groove direction of the first longitudinal groove  621  or the first lateral groove  622  and slightly tilting from an upstanding state to enter. 
     The leading portion of the link C 1   a  in the state of slightly tilting from the upstanding state enters the expanded groove part  624  to give a trigger for later-explained rotation of the link C 1   a . This can release the load chain C 1  from being stuck. 
     Note that the expanded groove part  624  larger in size is more preferable. 
     However, if the expanded groove part  624  is too large, a space where the limit switch  120  is to be installed in a range where the lower hook  80  collides around the chain inlet/outlet  611  is no longer present. Hence, between the adjacent expanded groove parts  624 , a space SP for installing a pressed part  121  of the limit switch  120  is provided. This space SP is preferably present in a circular range having a radius from the center of the chain inlet/outlet  611  to an end portion most apart from the expanded groove part  624 . 
     Further, as illustrated in  FIG.  7   , a stepped bottom surface part  625  is provided on the deep side (Z 1  side) of the body part  20  in the first guide groove  620 . The stepped bottom surface part  625  is a portion which is a boundary with the second guide groove  630 . In other words, since the first guide groove  620  and the second guide groove  630  are different in groove length by the presence of the expanded groove parts  624 , the stepped bottom surface part  625  as illustrated in  FIG.  7    is formed. 
     Here, when it is assumed that a depth from the bottom surface  33  to the stepped bottom surface part  625  is a depth H 1 , the depth H 1  is set so that when a link C 1   a  (abutting link) is present at one of the narrowed parts  623  of the bottom surface  33  and a link C 1   a  adjacent thereto (adjacent link) rotates using the abutting link C 1   a  as a fulcrum, the link C 1   a  (adjacent link) does not collide with the stepped bottom surface part  625 . This prevents the rotation of the link C 1   a  entered the first guide groove  620  from being obstructed by the stepped bottom surface part  625 , thus making it possible to release the load chain C 1  from being stuck. 
     Note that a portion of the stepped bottom surface part  625  closer to the center of the chain inlet/outlet  611  is provided with an arc-shaped part  625   a . Therefore, even if the link C 1   a  collides with the stepped bottom surface part  625 , the link C 1   a  is smoothly guided to the second guide groove  630  side owing to the presence of the arc-shaped part  625   a . Note that instead of providing the stepped bottom surface part  625 , a boundary portion between the first guide groove  620  and the second guide groove  630  may be provided in a curved shape as a whole. 
     Further, the second longitudinal groove  631  present in the second guide groove  630  is made to correspond to a length M 2  in a short side direction of the link C 1   a , and the width M 2  is necessary and sufficient for guiding the link C 1   a . Further, the second lateral groove  632  present in the second guide groove  630  is also made to correspond to the length M 2  in the short side direction of the link C 1   a , and the width M 2  is necessary and sufficient for guiding the link C 1   a . When the link C 1   a  enters the second longitudinal groove  631  or the second lateral groove  632 , the orientation of the link C 1   a  is further adjusted. 
     Further, the limit switch  120  is a mechanical switch which the lower hook  80  can press. The pressed part  121  of the limit switch  120  projects from the bottom surface  33 , and the pressed part  121  is provided in a range where the lower hook  80  collides. Note that at least a part of the pressed part  121  preferably reaches the above-explained space SP. 
     Note that as illustrated in  FIG.  4   , a protective cover  130  is attached to an arrangement section of the limit switch  120  of the guide member  60  in order to protect the limit switch  120  from the external part. 
     &lt;Regarding the Action&gt; 
     The action of the electric chain block  10  having the above configuration will be explained below. In the electric chain block  10 , in the case where the load chain C 1  sags because no tension is applied thereto when the load chain C 1  is hoisted and the links C 1   a  sequentially enter the chain inlet/outlet  611 , the orientations of the links C 1   a  are not adjusted at the stage before the links C 1   a  enter the chain inlet/outlet  611 . 
     When the load chain C 1  is hoisted in a state where the links C 1   a  are not aligned, the load chain C 1  may get stuck. An example of such getting stuck is illustrated in  FIG.  9   .  FIG.  9    is a view illustrating an example in which the load chain C 1  gets stuck around a current chain inlet/outlet  611 B. Note that the chain inlet/outlet  611 B illustrated in  FIG.  9    has a longitudinal groove  641 B and a lateral groove  642 B constant in groove width. 
     In the state illustrated in  FIG.  9   , it is assumed that a link C 1   a  which has already entered the chain inlet/outlet  611 B (the lateral groove  642 B in  FIG.  9   ) is a first link C 11   a , a link C 1   a  coupled to the first link C 11   a  is a second link C 12   a , and another link C 1   a  coupled to the second link C 12   a  is a third link C 13   a.    
     Here, in the case where the second link C 12   a  collides with the point P near the chain inlet/outlet  611  of the bottom surface  33  and the third link C 13   a  collides with the periphery of the chain inlet/outlet  611 , when the first link C 11   a  is pulled in with the rotation of the load sheave  50 , the second link C 12   a  tries to rotate to the side where it presses the bottom surface  33  (an arrow F side in  FIG.  9   ). 
     In this case, since the third link C 13   a  collides with the bottom surface  33  near the chain inlet/outlet  611  as indicated with a circular shape of a two-dotted chain line in  FIG.  7   , the second link C 12   a  inclines in a manner to be away from the bottom surface  33  on its third link C 13   a  side and to be in contact with the bottom surface  33  at the point P on its side away from the third link C 13   a  in contrast thereto. Therefore, when the second link C 12   a  is pulled in by the first link C 11   a , the first link C 11   a  tries to rotate the second link C 12   a  in a manner to further press the point P into the bottom surface  33  (namely, around the arrow F). 
     However, the collision of the second link C 12   a  with the point P hinders the second link C 12   a  from further rotating, causing the load chain C 1  to get stuck. 
       FIG.  10    is a view illustrating an image where the load chain C 1  is released from being stuck around the chain inlet/outlet  611  owing to the presence of the expanded groove part  624 . As illustrated in  FIG.  10   , the electric chain block  10  in this embodiment is brought into a state where the aforementioned point P is not present at the bottom surface  33  but is present at the expanded groove part  624  because of the provision of the expanded groove part  624 . This brings the second link C 12   a  into a state where its pull-in leading side enters the first longitudinal groove  621  or the first lateral groove  622 . Accordingly, in the case where the second link C 12   a  is pulled in by the first link C 11   a , the second link C 12   a  can change its orientation without causing jamming being the hindrance to the rotation as in the case where the point P is present at the bottom surface  33 . 
     Note that since the orientation of the second link C 12   a  can be changed as explained above, each link C 1   a  can be smoothly pulled into the chain inlet/outlet  611  thereafter. 
     &lt;Regarding the Effects&gt; 
     The electric chain block  10  having the above configuration includes the body part  20  which includes the motor  40  and the load sheave  50 , and the chain inlet/outlet  611  which is provided at the bottom surface  33  of the body part  20  and through which the load chain C 1  on the load side gets in/out, and the chain inlet/outlet  611  has the first guide groove  620 . The first guide groove  620  is provided on the opening side of the chain inlet/outlet  611 , and includes the first longitudinal groove  621  and the first lateral groove  622  which have the groove length corresponding to the length in the long side direction of each link C 1   a  of the load chain C 1 , and the first longitudinal groove  621  and the first lateral groove  622  orthogonally cross each other. Further, the chain inlet/outlet  611  has the second guide groove  630 , and the second guide groove  630  is provided on the side deeper in the body part  20  than the first guide groove  620  is, and includes the second longitudinal groove  631  and the second lateral groove  632  which have the groove length corresponding to the length in the short side direction of each link C 1   a  of the load chain C 1 , and the second longitudinal groove  631  and the second lateral groove  632  orthogonally cross each other. 
     Further, the first guide groove  620  has the narrowed parts  623  which face each other across the groove width L2 corresponding to the wire diameter of the link C 1   a  of the load chain C 1  in the width direction of the first longitudinal groove  621  and face each other across the groove width L2 in the width direction of the first lateral groove  622  to determine into which of the first longitudinal groove  621  and the first lateral groove  622  each link C 1   a  of the load chain C 1  is introduced when the link C 1   a  is pulled in. Further, the first guide groove  620  has the expanded groove parts  624  which are provided on the outside further away from the center of the chain inlet/outlet  611  than the narrowed parts  623  are and have the width larger than the groove width L2. 
     As explained above based on  FIG.  10   , the presence of the expanded groove part  624  enables the leading side of the second link C 12   a  to enter the expanded groove part  624 . Therefore, it is possible to prevent the second link C 12   a  from colliding with the bottom surface  33  at the point P as illustrated in  FIG.  9    and to make the pull-in leading side of the second link C 12   a  enter the first longitudinal groove  621  or the first lateral groove  622 . Thus, in the case where the second link C 12   a  is pulled in by the first link C 11   a , the second link C 12   a  can change its orientation without causing jamming being the hindrance to the rotation as in the case where the point P is present at the bottom surface  33 . Therefore, after the change of the orientation of the second link C 12   a , each link C 1   a  can be smoothly pulled into the chain inlet/outlet  611 . Therefore, even if the link C 1   a  falls sideways or inclines, the link C 1   a  can be made to easily enter the chain inlet/outlet  611 . 
     Further, the first guide groove  620  is provided with the narrowed parts  623 , so that the narrowed parts  623  can limit the orientation of the link C 1   a . In other words, it is possible to adjust the direction of the link C 1   a  entered the first longitudinal groove  621  or the first lateral groove  622  so as to be along either the first longitudinal groove  621  or the first lateral groove  622 . This can prevent the link C 1   a , in a state of not being adjusted in the direction of either the first longitudinal groove  621  or the first lateral groove  622 , from entering the inside of the first longitudinal groove  621  or the first lateral groove  622 , thereby preventing failure of hoisting with the load sheave  50 . 
     Further, the chain inlet/outlet  611  has the narrowed parts  623  and the expanded groove parts  624  as explained above, thus eliminating the need to form a projecting portion with respect to the bottom surface  33 . Therefore, when the lower hook  80  collides with the bottom surface  33  near the chain inlet/outlet  611 , the pressed part  121  of the limit switch  120  can be easily pressed. 
     Further, in this embodiment, the first longitudinal groove  621  and the first lateral groove  622  are formed at a depth where the link C 1   a  to be pulled into the first longitudinal groove  621  or the first lateral groove  622  reaches the inside of the second guide groove  630  and is rotatable in a manner to fall down using the link C 1   a  (the second link C 12   a ) in contact with the bottom surface  33  as a fulcrum. 
     This configuration ensures that using the link C 1   a  in collision with the bottom surface  33  near the chain inlet/outlet  611  as a fulcrum as indicated with the circular shape of the two-dotted chain line in  FIG.  7   , the link C 1   a  (adjacent link) coupled to the colliding link C 1   a  reaches the inside of the second guide groove  630  and rotates in a manner to fall down in a state of having entered the first guide groove  620 . This prevents the rotation of the link C 1   a  entered the first guide groove  620  from being obstructed, thus making it possible to release the load chain C 1  from being stuck. 
     Further, in this embodiment, the narrowed parts  623  are provided in a manner to be flush with the bottom surface  33  and to continue into the bottom surface  33 . Therefore, it is possible to apply sufficient strength to the narrowed parts  623  and to improve the abrasion resistance of the narrowed parts  623 . 
     Further, in this embodiment, at least a part of the pressed part  121  of the limit switch  120  is arranged in the space SP located in the range where the base part  81  of the lower hook  80  collides with the bottom surface  33  near the chain inlet/outlet  611 . Then, the pressed part  121  is pressed to stop the driving of the motor  40 . 
     Since at least a part of the pressed part  121  is arranged in the space SP as explained above, it becomes possible to surely press the pressed part  121  when the lower hook  80  is lifted up to the upper limit position where it collides with the bottom surface  33 . Thus, it is possible to surely stop the driving of the motor  40 . Therefore, it is possible to prevent damage to the body part  20  by continuing to drive the motor  40 . 
     Modified Example 
     One embodiment of the present invention has been explained above, and the present invention is modifiable other than that. Hereinafter, the modifiable one will be explained. 
     In the above embodiment, the chain inlet/outlet  611  on the lower hook  80  side is explained. However, the side surface chain inlet/outlet  651  may also be made to include a first guide groove similar to the above-explained first guide groove  620  having the narrowed parts and the expanded groove parts and a second guide groove similar to the second guide groove  630  located on the deep side of the first guide groove. 
     Further, in the above embodiment, the narrowed parts  623  are provided to be flush with the bottom surface  33 . However, the narrowed parts  623  are not flush with the bottom surface  33 , but may slightly project or slightly dent to an extent not obstructing the press of the pressed part  121 . 
     REFERENCE SIGNS LIST 
       10  . . . electric chain block,  20  . . . body part,  30  . . . body,  31  . . . side surface,  32  . . . top surface,  33  . . . bottom surface,  34  . . . shaft hole,  40  . . . motor,  50  . . . load sheave,  51  . . . chain pocket,  60  . . . guide member,  67  . . . arc-shaped covering member,  70  . . . upper hook,  71  . . . hook part,  72  . . . hook receiving part,  72   a  . . . attachment hole,  80  . . . lower hook,  81  . . . base part,  82  . . . hook part,  90  . . . chain bucket,  100  . . . bucket attachment bracket,  105  . . . bucket attachment part,  105   a  . . . attachment arm,  105   b  . . . attachment hole,  110  . . . coupling tool,  120  . . . limit switch,  121  . . . pressed part,  130  . . . protective cover,  610  . . . first guide passage,  611  . . . chain inlet/outlet,  611 B . . . chain inlet/outlet,  620  . . . first guide groove,  621  . . . first longitudinal groove,  622  . . . first lateral groove,  623  . . . narrowed part,  623   a  . . . tip part,  623   b  . . . plane part,  624  . . . expanded groove part,  625  . . . stepped bottom surface part,  625   a  . . . arc-shaped part,  630  . . . second guide groove,  631  . . . second longitudinal groove,  632  . . . second lateral groove,  641 B . . . longitudinal groove,  642 B . . . lateral groove,  650  . . . second guide passage,  651  . . . side surface chain inlet/outlet, B . . . depth, C . . . depth, C 1  . . . load chain, C 11   a  . . . first link, C 12   a  . . . second link, C 13   a  . . . third link, C 1   a  . . . link, S 1  . . . link shaft, SP . . . space