Abstract:
A damper apparatus possible to suppress abnormal sounds immediately after the locking of gears has been released is provided. In a first lock mechanism of the damper apparatus, a first arcuate outer-peripheral part peripherally adjacent to a teeth-missing gear in a drive gear enters a portion of a plurality of teeth in which some teeth are narrowed in the axial direction to restrain a sector gear, the teeth being meshed with the drive gear in the sector gear. In the tooth nearest to the first arcuate outer-peripheral part in the teeth-missing gear, the curvature of a first tooth flank on the side opposite the first arcuate outer-peripheral part is less than the curvature of a second tooth flank on the first arcuate outer peripheral part side, and the tooth has a curved surface continuous from the first tooth flank to the second tooth flank.

Description:
TECHNICAL FIELD 
       [0001]    The disclosure relates to a damper device which is used in a cold air passage of a refrigerator or the like. 
       BACKGROUND ART 
       [0002]    In a damper device which is used in a cold air passage of a refrigerator or the like, a structure has been proposed in which a baffle is turnably driven by, for example, a drive mechanism including a stepping motor and a gear train to open and close an opening part formed in a frame (see Patent Literature 1). Further, in the damper device described in Patent Literature 1, a lock mechanism for maintaining a posture of the baffle is provided between a drive gear and a sector gear used in the gear train. In the lock mechanism, a circular arc-shaped outer peripheral part of the drive gear is entered to portions whose dimensions in an axial line direction are narrowed of a second and a third teeth from one end in a circumferential direction in a plurality of the teeth of the sector gear and thereby the sector gear is restricted. 
       CITATION LIST 
     Patent Literature 
       [0003]    [Patent Literature 1] Japanese Patent Laid-Open No. 2003-240102 
       SUMMARY OF THE DISCLOSURE 
     Technical Problem 
       [0004]    However, for example, in a case that a baffle is started to drive in an open direction from a state that the baffle is held in a closing posture by the lock mechanism described in Patent Literature 1, when an urging force is acted on the baffle in the open direction, the teeth of the sector gear having been pressure-contacted and restricted by the circular arc-shaped outer peripheral part of the drive gear are rapidly released. Therefore, the sector gear is turned rapidly and the members are strongly contacted with each other and, as a result, an abnormal noise is occurred. 
         [0005]    In view of the problem described above, the disclosure provides a damper device which is capable of restraining occurrence of an abnormal noise just after a locking state of the gears is released. 
       Means to Solve the Problems 
       [0006]    To solve the above mentioned problem, the disclosure provides a damper device including a frame in which an opening part is formed, a baffle configured to open and close the opening part, a drive mechanism structured to drive the baffle, and a case which accommodates the drive mechanism. The drive mechanism includes a stepping motor and a gear train structured to transmit rotation of the stepping motor, and the gear train includes a drive gear and a sector gear engaged with the drive gear and driven by the drive gear. A first lock mechanism is structured between the drive gear and the sector gear at a movement restricted position in one of a closing direction and an open direction of the baffle, and the first lock mechanism prevents turning of the sector gear to the other of the closing direction and the open direction of the baffle. The first lock mechanism is structured so that a first circular arc-shaped outer peripheral part of the drive gear concentrically formed so as to have the same or larger diameter than a tooth tip circle of a partially toothless gear engaged with the sector gear and disposed at a position adjacent in a circumferential direction to the partially toothless gear is entered into a portion of a tooth whose dimension in an axial line direction is narrowed of a plurality of teeth of the sector gear engaged with the drive gear and thereby the sector gear is restricted. In addition, a tooth on the most first circular arc-shaped outer peripheral part side of the partially toothless gear is formed so that a curvature of a first tooth face on an opposite side to the first circular arc-shaped outer peripheral part side is smaller than a curvature of a second tooth face on the first circular arc-shaped outer peripheral part side. 
         [0007]    In the disclosure, a first lock mechanism is structured at a movement restricted position in one of a closing direction and an open direction of the baffle for preventing turning of the sector gear and thus the baffle is hard to be displaced from a stopped state. Further, in the disclosure, the first lock mechanism is structured so that the first circular arc-shaped outer peripheral part of the drive gear adjacent to the partially toothless gear is entered to the portion of a tooth whose dimension in the axial line direction is narrowed of the sector gear and thereby the sector gear is restricted. In the disclosure, a tooth on the most first circular arc-shaped outer peripheral part side of the partially toothless gear is formed so that a curvature of a first tooth face on an opposite side to the first circular arc-shaped outer peripheral part side is smaller than a curvature of a second tooth face on the first circular arc-shaped outer peripheral part side. Therefore, a tooth of the sector gear which is pressure-contacted and restricted by the first circular arc-shaped outer peripheral part of the drive gear is gradually released from the drive gear when the baffle is started to drive to the other direction. Accordingly, even when an urging force is acted on the baffle in the other direction, the sector gear is turned gradually and thus occurrence of an abnormal noise caused by a collision between the members or the like can be restrained. 
         [0008]    In the disclosure, it is preferable that a tooth face of the tooth on the most first circular arc-shaped outer peripheral part side of the partially toothless gear is formed in a continuously curved face from a side of the first tooth face to the second tooth face. According to this structure, the tooth of the sector gear which is pressure-contacted and restricted by the first circular arc-shaped outer peripheral part of the drive gear is gradually released from the drive gear. Therefore, even when an urging force is acted on the baffle in the other direction, the sector gear is turned gradually. 
         [0009]    In the disclosure, it is preferable that the tooth face of the tooth on the most first circular arc-shaped outer peripheral part side of the partially toothless gear is formed in a continuously curved face from the side of the first tooth face to the first circular arc-shaped outer peripheral part. According to this structure, the tooth of the sector gear which is pressure-contacted and restricted by the first circular arc-shaped outer peripheral part of the drive gear is gradually released from the drive gear. Therefore, even when an urging force is acted on the baffle in the other direction, the sector gear is turned gradually. 
         [0010]    In the disclosure, it may be structured that the first lock mechanism prevents turning of the sector gear at the movement restricted position in the closing direction of the baffle. 
         [0011]    The disclosure is especially effective in the structure that a portion of the baffle contacting with the frame when the baffle sets the opening part in a closed state is made of an elastic member, and the elastic member is elastically deformed by contacting with the frame in a state that the opening part is closed by the baffle. In a case that the portion of the baffle contacted with the frame is made of an elastic member, an urging force in an open direction is applied to the baffle in a state that the opening part of the frame is closed by the baffle and thus, when the baffle is started to drive in an open direction, the sector gear is going to turn rapidly. However, according to the disclosure, the tooth face of the partially toothless gear is structured as described above and thus rapid turning of the sector gear can be restrained. 
         [0012]    In the disclosure, it is preferable that a first stopper mechanism is structured between the drive gear and the case and the first stopper mechanism restricts a movable range in a first turning direction of the drive gear when the baffle is turned in the closing direction and, in the first lock mechanism, a dimension in an axial line direction of a tooth at the most end position in a circumferential direction of a plurality of teeth of the sector gear engaged with the drive gear is narrowed. According to this structure, the position where the first stopper mechanism is operated is set as a starting point and, when the baffle is driven in either direction of an open direction and a closing direction, a drive signal having the same number of steps is supplied to the stepping motor. Therefore, in a case that the opening part of the frame is to be set in a closed state by the baffle, even when the baffle is further driven in a closing direction from a state that the baffle is abutted with the frame, step-out of the stepping motor is hard to be occurred because the number of steps is set with the time point when the first stopper mechanism is operated as the starting point. Accordingly, a situation that the gears of the gear train are momentarily reversed is hard to be occurred due to step-out and thus an abnormal noise caused by a collision between the teeth can be restrained. Further, since the first stopper mechanism is provided, it is sufficient that the first lock mechanism prevents turning to one side direction of the sector gear. Therefore, it is sufficient that a dimension in the axial line direction of the tooth located on the most end position in a circumferential direction of the sector gear is narrowed and thus the portion for structuring the first lock mechanism in the sector gear can be narrowed. Accordingly, the size of the sector gear can be reduced. 
         [0013]    In the disclosure, it is preferable that a second stopper mechanism which restricts a movable range in a second turning direction of the drive gear when the baffle is turned in the open direction, and the movable range of the baffle set in a range from a position where the first stopper mechanism is operated to a front position before the second stopper mechanism is operated. According to this structure, even in a case that the baffle is running out of control in an open direction, the run-away of the baffle can be prevented by the second stopper mechanism. Further, normally, the number of steps of the stepping motor is set at a front position before the second stopper mechanism is operated and thus a situation is hard to be occurred that the second stopper mechanism is operated to cause step-out of the stepping motor. 
         [0014]    In the disclosure, it is preferable that a second lock mechanism is structured between the drive gear and the sector gears for holding the sector gear in a stopped state at the front position and the second lock mechanism is structured so that a second circular arc-shaped outer peripheral part of the drive gear concentrically formed so as to have the same or larger diameter than the tooth tip circle of the partially toothless gear engaged with the sector gear and disposed at a position adjacent in the circumferential direction to the partially toothless gear is entered into a portion of a tooth whose dimension in an axial line direction is narrowed of a plurality of teeth of the sector gear engaged with the drive gear and thereby the sector gear is restricted. Therefore, the baffle in the open posture can be restrained from flapping due to fluid pressure. 
         [0015]    In the disclosure, it is preferable that the drive gear is formed with a circular arc-shaped protruded part on an opposite side to a side having teeth of the partially toothless gear, the circular arc-shaped protruded part is connected from the first circular arc-shaped outer peripheral part to the second circular arc-shaped outer peripheral part, and an outer peripheral face of the circular arc-shaped protruded part is provided with the same or larger diameter than the tooth tip circle of the partially toothless gear and formed concentrically with the tooth tip circle. 
         [0016]    In the disclosure, the sector gear is, for example, an output gear connected with the baffle. 
         [0017]    In the disclosure, it is preferable that an imaginary line which connects a turning center position of the drive gear and a turning center position of the sector gear is obliquely extended for all of four side plate parts of the case which surround the drive mechanism. According to this structure, the drive gear can be disposed corresponding to the shape of the sector gear and thus a space required to provide the drive mechanism can be narrowed. Therefore, the size of the case can be reduced. 
         [0018]    In the disclosure, it is preferable that a pitch circle radius of a large diameter gear of a first gear engaged with a motor pinion of the stepping motor is set so that a length obtained by adding a pitch circle radius of the motor pinion to the pitch circle radius of the large diameter gear of the first gear is larger than a length obtained by adding a radius of the stepping motor and a pitch circle radius of a small diameter gear of the first gear. According to this structure, when viewed in turning center axial line directions of the stepping motor and the first gear, the rotation center shaft of the first gear is not overlapped with the stepping motor. Therefore, a rotation shaft of the first gear and a support shaft rotatably supporting the first gear can be easily disposed. 
       Effects of the Disclosure 
       [0019]    In the disclosure, a first lock mechanism is structured at a movement restricted position in one of a closing direction and an open direction of the baffle for preventing turning of the sector gear and thus the baffle is hard to be displaced from a stopped state. Further, in the disclosure, in the first lock mechanism, the first circular arc-shaped outer peripheral part of the drive gear adjacent to the partially toothless gear is entered to a portion of a tooth whose dimension in the axial line direction is narrowed of the sector gear and thereby the sector gear is restricted. In this case, a tooth on the most first circular arc-shaped outer peripheral part side of the partially toothless gear is formed so that a curvature of a first tooth face on an opposite side to the first circular arc-shaped outer peripheral part side is smaller than a curvature of a second tooth face on the first circular arc-shaped outer peripheral part side. Therefore, a tooth of the sector gear which is pressure-contacted and restricted by the first circular arc-shaped outer peripheral part of the drive gear is gradually released from the drive gear when the baffle is started to drive in the other direction. Accordingly, even when an urging force is acted on the baffle in the other direction, the sector gear is turned gradually and thus occurrence of an abnormal noise caused by a collision between the members or the like can be restrained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIGS. 1( a ) and 1( b )  are explanatory views showing a damper device to which the disclosure is applied. 
           [0021]      FIG. 2  is an exploded perspective view showing a baffle and the like used in a damper device to which the disclosure is applied. 
           [0022]      FIG. 3  is an explanatory view showing a drive mechanism of a damper device to which the disclosure is applied. 
           [0023]      FIGS. 4( a ), 4( b ) and 4( c )  are explanatory views showing structures of a drive gear, a sector gear and the like which are used in a drive mechanism of a damper device to which the disclosure is applied. 
           [0024]      FIG. 5  is an explanatory view showing a first stopper mechanism structured in a drive mechanism of a damper device to which the disclosure is applied. 
           [0025]      FIGS. 6( a ) and 6( b )  are explanatory views showing a tooth face of a tooth on the most first circular arc-shaped outer peripheral part side in a partially toothless gear of a drive gear in a damper device. 
           [0026]      FIG. 7  is a graph showing an angular variation of a common normal line of a tooth of a drive gear and a tooth of a sector gear accompanied with turning of the drive gear in a damper device. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0027]    A damper device for a refrigerator to which the disclosure is applied will be described below with reference to the accompanying drawings. In the following descriptions, a turning center axial line of a baffle  4  is referred to as an “L”, a direction along the turning center axial line “L” is referred to as an “X” direction, a direction in which an opening part faces is referred to as a “Z” direction, and a direction perpendicular to the “X” direction and the “Z” direction is referred to as a “Y” direction. Further, one side in the “X” direction is referred to as “X 1 ”, the other side in the “X” direction is referred to as “X 2 ”, one side in the “Y” direction is “Y 1 ”, the other side in the “Y” direction is “Y 2 ”, one side in the “Z” direction is “Z 1 ”, and the other side in the “Z” direction is “Z 2 ”. Further, in the following descriptions, the turning center axial line “L” is set in a horizontal direction, one side “Y 1 ” in the “Y” direction is a lower side in a gravity direction, and the other side “Y 2 ” in the “Y” direction is an upper side in the gravity direction. 
       (Entire Structure) 
       [0028]      FIGS. 1( a ) and 1( b )  are explanatory views showing a damper device  1  to which the disclosure is applied.  FIG. 1( a )  is a perspective view which is viewed from a side where a baffle  4  is disposed with respect to an opening part  210 , and  FIG. 1( b )  is its exploded perspective view.  FIG. 2  is an exploded perspective view showing a baffle  4  and the like used in the damper device  1  to which the disclosure is applied.  FIGS. 1( a ) and 1( b )  and  FIG. 2  show a state that the opening part  210  is set in a closed state by the baffle  4 . 
         [0029]    As shown in  FIGS. 1( a ) and 1( b )  and  FIG. 2 , a damper device  1  in this embodiment includes a frame  2  in which a rectangular opening part  210  (see  FIG. 2 ) is formed, a case  3  which accommodates a drive mechanism  6  in its inside, and a baffle  4  for opening and closing the opening part  210  of the frame  2 . The case  3  and the frame  2  are connected with each other by a hook mechanism  11  or the like. 
         [0030]    The frame  2  is provided with a rectangular end plate part  21  in which the opening part  210  is formed, and a body part  22  in a rectangular tube shape which is protruded to the other side “Z 2 ” in the “Z” direction from an outer side edge of the end plate part  21 . The body part  22  is provided with a side plate part  221  on an opposite side to the case  3 , a connecting plate part  25  facing the side plate part  221  on the case  3  side, and side plate parts  222  and  223  which connect the side plate part  221  with the connecting plate part  25 . The connecting plate part  25  is protruded to the other side “Z 2 ” in the “Z” direction with respect to the side plate parts  221 ,  222  and  223  and is connected with the case  3 . 
         [0031]    A seal plate part  26  in a rectangular tube shape is formed in the end plate part  21  so as to protrude from an edge of the opening part  210  toward a side where the baffle  4  is located. The baffle  4  is abutted with the seal plate part  26  and thereby the opening part  210  is set in a closed state. Further, a sheet-shaped heater  9  is attached to a face of the end plate part  21  on the side where the baffle  4  is located so as to surround the opening part  210  (surrounding the seal plate part  26 ). 
         [0032]    In this embodiment, a drive mechanism  6  turns the baffle  4  around the turning center axial line “L” extended in the “X” direction (horizontal direction) to open and close the opening part  210 . The drive mechanism  6  changes a posture of the baffle  4  between a closing posture, which is obtained by turning the baffle  4  in a closing direction as shown by the arrow “A” with the turning center axial line “L” as a turning center to close the opening part  210  by the baffle  4 , and an open posture which is obtained by turning the baffle  4  in an open direction as shown by the arrow “B” with the turning center axial line “L” as a turning center to open the opening part  210 . 
         [0033]    The damper device  1  is disposed on an inner side of a duct structuring a cold air passage. Cold air is flowed through the opening part  210  from a side opposite to a side where the baffle  4  is disposed with respect to the opening part  210 . Alternatively, cold air may be flowed through the opening part  210  from a side where the baffle  4  is disposed with respect to the opening part  210 . In this embodiment, cold air is flowed through the opening part  210  from a side opposite to a side where the baffle  4  is disposed with respect to the opening part  210 . 
       (Structure of Baffle  4 ) 
       [0034]    The baffle  4  includes an opening/closing (opening and closing) plate  40  having a flat plate part  41  whose size is larger than the opening part  210 , and a sheet-shaped elastic member  49  which is stuck on a face on an opening part  210  side of the opening/closing plate  40  and is made of foamed polyurethane or the like. The elastic member  49  is abutted with the periphery of the opening part  210  (seal plate part  26 ) and closes the opening part  210 . A face of the opening/closing plate  40  on an opposite side to the opening part  210  of the flat plate part  41  is formed with ribs  42 ,  43 ,  44  and  45  extended along an outer side edge of the baffle  4 . 
         [0035]    The baffle  4  is provided with a shaft part  46  protruded toward one side “X 1 ” in the “X” direction on a side where the rib  44  is located in the flat plate part  41 . The shaft part  46  is coaxially formed with the turning center axial line “L”. The shaft part  46  is turnably supported by a hole  250  formed in the connecting plate part  25  of the frame  2  and is connected with the drive mechanism  6  in this state. Further, the baffle  4  is provided with a shaft part  48  protruded toward the other side “X 2 ” in the “X” direction on a side where the rib  44  is located in the flat plate part  41 . A protruded part  480  which is turnably supported by the frame  2  is protruded from the shaft part  48  toward the other side “X 2 ” in the “X” direction (outer side). 
       (Structure of Drive Mechanism  6 ) 
       [0036]      FIG. 3  is an explanatory view showing the drive mechanism  6  of the damper device  1  to which the disclosure is applied.  FIG. 3  shows a closed state that the opening part  210  is set in a closed state by the baffle  4 . 
         [0037]    As shown in  FIG. 3 , the drive mechanism  6  includes a stepping motor  60  which is disposed on an inner side of the case  3  and a gear train  65  for transmitting rotation of the stepping motor  60  to the baffle  4  on an inner side of the case  3 . The case  3  is provided with a bottom plate part  31  and a body part  32  in a rectangular tube shape which is protruded to a side of the frame  2  from the bottom plate part  31 . The body part  32  is provided with side plate parts  321  and  322  facing in the “Z” direction and side plate parts  323  and  324  facing in the “Y” direction. The bottom plate part  31  and the body part  32  are formed in a quadrangular shape whose long side is extended in the “Y” direction and its short side is extended in the “Z” direction when viewed in the “X” direction. The stepping motor  60  is held by the case  3  between the frame  2  and the case  3 . 
         [0038]    The gear train  65  includes a first gear  66  provided with a large diameter gear  661  engaged with a motor pinion  601 , a second gear  67  provided with a large diameter gear  671  engaged with a small diameter gear (not shown) of the first gear  66 , and a drive gear  68  provided with a large diameter gear  681  engage with a small diameter gear  672  of the second gear  67 . Therefore, in the gear train  65 , the first gear  66 , the second gear  67  and the drive gear  68  structure a reduction gear train. Further, the gear train  65  includes a sector gear  69  which is engaged with the drive gear  68  and is driven by the drive gear  68 . The sector gear  69  is a final gear (output gear) located in the last stage of the gear train  65  and is connected with the baffle  4 . In this embodiment, the second gear  67 , the drive gear  68  and the sector gear  69  are turnably supported by the bottom plate part  31  of the case  3 . 
         [0039]    In this embodiment, a pitch circle radius of the large diameter gear  661  of the first gear  66  is set so that a length obtained by adding the pitch circle radius of the large diameter gear  661  to a pitch circle radius of the motor pinion  601  is larger than a length obtained by adding a radius of the stepping motor  60  and a pitch circle radius of the small diameter gear (not shown) of the first gear. Therefore, when viewed in the turning center axial line directions of the stepping motor  60  and the first gear  66 , the small diameter gear (not shown) of the first gear  66  is not overlapped with an outer diameter of the stepping motor  60 . Accordingly, for example, a rotation shaft of the first gear  66  and its support shaft are not required to be supported by a main body part  605  or the like of the stepping motor  60  and thus a structure for rotatably disposing the first gear  66  can be simplified. Further, since an outer diameter of the first gear  66  is large, the number of gears for structuring the deceleration mechanism in the gear train  65  can be reduced. In this embodiment, both ends of a rotation shaft  660  of the first gear  66  are supported by the bottom plate part  31  of the case  3  and the connecting plate part  25  of the frame  2  on one side in the “Y” direction with respect to the main body part  605  of the stepping motor  60 . 
       (Detailed Structure of Drive Gear  68  and the Like) 
       [0040]      FIGS. 4( a ), 4( b ) and 4( c )  are explanatory views showing structures of the drive gear  68 , the sector gear  69  and the like which are used in the drive mechanism  6  of the damper device  1  to which the disclosure is applied.  FIG. 4( a )  is a perspective view showing a state that the drive gear  68  and the sector gear  69  are supported in the case  3  which is viewed from the other side “X 2 ” in the “X” direction (from a side where the frame  2  is disposed).  FIG. 4( b )  is an exploded perspective view showing a state that the drive gear  68  and the sector gear  69  are detached from the case  3  which is viewed from the other side “X 2 ” in the “X” direction (from a side where the frame  2  is disposed).  FIG. 4( c )  is a perspective view showing the drive gear  68  and the sector gear  69  viewed from one side “X 1 ” in the “X” direction (from an opposite side to the frame  2 ).  FIG. 5  is an explanatory view showing a first stopper mechanism  71  structured in the drive mechanism  6  of the damper device  1  to which the disclosure is applied and  FIG. 5  is a “YZ” cross-sectional view in which the drive gear  68  and the like is cut at a position where a stopper protruded part  39  is formed. 
         [0041]      FIGS. 4( a ), 4( b ) and 4( c )  and  FIG. 5  show a state that the baffle  4  sets the opening part  210  in a closed state. Further, in the following descriptions, a turning direction of the drive gear  68  when the baffle  4  is driven in a closing direction is referred to as a first direction (direction as shown by the arrow “B 1 ”), and a turning direction of the drive gear  68  when the baffle  4  is driven in an open direction is referred to as a second direction (direction as shown by the arrow “A 1 ”). Further, a turning direction of the sector gear  69  when the baffle  4  is driven in a closing direction is indicated by the arrow “B 2 ”, and a turning direction of the drive gear  68  when the baffle  4  is driven in an open direction is indicated by the arrow “A 2 ”. 
         [0042]    As shown in  FIGS. 4( a ) and 4( b ) , the bottom plate part  31  of the case  3  is formed with a tube part  37 , which turnably supports the sector gear  69  near a corner of the side plate parts  322  and  323 , and a stepped support shaft  36  which turnably supports the drive gear  68  at a position obliquely separated in the “Y” direction and the “Z” direction from the tube part  37 . Therefore, an imaginary line which connects the turning center position of the drive gear  68  with the turning center position of the sector gear  69  is obliquely extended for all of four side plate parts  321 ,  322 ,  323  and  324  which surround the drive mechanism  6  in the case  3 . In other words, the drive gear is provided at a preferable position corresponding to a shape of the sector gear  69 . Therefore, a space required to provide the drive mechanism  6  is narrow and thus the size of the case  3  can be reduced. 
         [0043]    In this embodiment, a stopper protruded part  39  extended in a circular arc shape with the support shaft  36  as a center is formed on a side with respect to the support shaft  36  in the bottom plate part  31  of the case  3 . The stopper protruded part  39  structures a first stopper mechanism  71  and a second stopper mechanism  72  described below by contacting with the drive gear  68 . 
         [0044]    In other words, the stopper protruded part  39  is provided in the bottom plate part  31  of the case  3  and the drive gear  68  is provided with a protruded part  688  and a protruded part  689 . The first stopper mechanism  71  is structured of the stopper protruded part  39  and the protruded part  689 , and the second stopper mechanism  72  is structured of the stopper protruded part  39  and the protruded part  688 . 
         [0045]    As shown in  FIG. 3  and  FIGS. 4( a ) and 4( b ) , the drive gear  68  is provided with a large diameter gear  681  formed of a spur gear around a shaft hole  680  to which the support shaft  36  formed in the case  3  is fitted, and a partially toothless gear  682  formed concentrically with the large diameter gear  681  on the other side “X 2 ” in the “X” direction of the large diameter gear  681 . In this embodiment, the partially toothless gear  682  is provided with a plurality of teeth  682   a  over an angular range of about 120°. Further, the drive gear  68  is formed with a circular arc-shaped protruded part  683  which is protruded from the large diameter gear  681  on the other side “X 2 ” in the “X” direction of the large diameter gear  681  so as to be lower than a dimension in an axial line direction (tooth width) of the partially toothless gear  682 . An outer peripheral face of the arc-shaped protruded part  683  is provided with the same as or larger diameter than a tooth tip circle of the partially toothless gear  682  and is formed concentric with the tooth tip circle. Alternatively, it may be structured that the outer peripheral face of the circular arc-shaped protruded part  683  is extended in a radial direction to a position where turning of the sector gear  69  is not disturbed. Further, the circular arc-shaped protruded part  683  is formed with slits  683   a  and  683   b  which are opened at an end face on the other side “X 2 ” in the “X” direction. 
         [0046]    In the outer peripheral face of the circular arc-shaped protruded part  683  structured as described above, an end part in the first direction shown by the arrow “B 1 ” is a first circular arc-shaped outer peripheral part  686  which structures a first lock mechanism  81  described below together with the case  3 , and an end part in the second direction shown by the arrow “A 1 ” is a second circular arc-shaped outer peripheral part  687  which structures a second lock mechanism  82  described below together with the case  3 . 
         [0047]    As shown in  FIG. 4( c )  and  FIG. 5 , in the drive gear  68 , a circular ring-shaped protruded part  684   a  is formed along an outer peripheral edge on one side “X 1 ” in the “X” direction of the large diameter gear  681 , and an circular ring-shaped protruded part  684   b  is formed along an inner peripheral edge so as to be concentric with the protruded part  684   a.    
         [0048]    A protruded part  688  extended in a radial direction so as to connect the protruded parts  684   a  and  684   b  with each other is formed between the protruded part  684   a  and the protruded part  684   b , and a protruded part  689  extended in the radial direction so as to connect the protruded parts  684   a  and  684   b  with each other is formed at a position separated in a circumferential direction from the protruded part  688 . In this embodiment, the protruded part  689  is formed at an angular position of about 150° from the protruded part  688  toward the first direction shown by the arrow “B 1 ” and, as a result, the protruded part  688  is formed at an angular position of about 210° from the protruded part  689  toward the first direction shown by the arrow “B 1 ”. 
         [0049]    In this embodiment, a recessed part  685  surrounded by the protruded parts  684   a ,  684   b ,  688  and  689  is utilized as a stopper arrangement space which is provided in a wider angular range between the protruded part  688  and the protruded part  689  in the circumferential direction (angular range of about 210° toward the first direction shown by the arrow “A 1 ” from the protruded part  688 ). In other words, when the support shaft  36  of the case  3  is fitted into the shaft hole  680  of the drive gear  68 , the stopper protruded part  39  formed in the bottom plate part  31  of the case  3  is located in an inside of the recessed part  685 . 
         [0050]    Therefore, when the drive gear  68  is turned toward the first direction shown by the arrow “B 1 ”, the protruded part  689  is abutted with the stopper protruded part  39  and the first stopper mechanism  71  which prevents further turning of the drive gear  68  is operated. On the other hand, when the drive gear  68  is turned toward the second direction shown by the arrow “A 1 ”, the protruded part  688  is abutted with the stopper protruded part  39  and the second stopper mechanism  72  which prevents further turning of the drive gear  68  is operated. 
       (Detailed Structure of Sector Gear  69 ) 
       [0051]    As shown in  FIG. 3  and  FIGS. 4( a ), 4( b ) and 4( c ) , the sector gear  69  is provided with a shaft part  690  which is fitted into the tube part  37  formed in the case  3  and an output shaft  691  formed on the other side in the “X” direction with respect to the shaft part  690 . The output shaft  691  is formed with flat face parts at positions facing each other and, on the other hand, a recessed part (not shown) having an opening part corresponding to a cross-sectional shape of the output shaft  691  is formed on a case  3  side of the shaft part  46  of the baffle  4  as described with reference to  FIGS. 1( a ) and 1( b )  and  FIG. 2 . Therefore, when the output shaft  691  is fitted into the recessed part formed in the shaft part  46  of the baffle  4 , turning of the output shaft  691  is transmitted to the baffle  4 . 
         [0052]    In the sector gear  69 , a column part  692  whose outer diameter is larger than the shaft part  690  and the output shaft  691  is formed between the shaft part  690  and the output shaft  691 . A plurality of teeth  694  is formed along an outer peripheral face of a circular arc part  693  which is formed on an outer peripheral side of the column part  692 . In this embodiment, reinforcing plates  695  are formed between both ends of the circular arc part  693  and the column part  692 . 
         [0053]    In a plurality of the teeth  694  arranged in a circumferential direction of the sector gear  69 , the tooth  694   a  located on the most end position in the direction shown by the arrow “A 2 ” is formed narrower in a dimension in an axial line direction (tooth width) than the adjacent teeth  694 . Further, in the plurality of the teeth  694  arranged in the circumferential direction of the sector gear  69 , the second and the third teeth  694   b  from the most end tooth in a direction shown by the arrow “B 2 ” are formed narrower in a dimension in the axial line direction (tooth width) than the adjacent teeth  694 . 
         [0054]    In the teeth  694   a  and  694   b , a space formed by making a tooth width of the tooth  694   a  narrow is a space into which the first circular arc-shaped outer peripheral part  686  of the drive gear  68  is entered to structure the first lock mechanism  81  together with the drive gear  68  as described below. Further, a space formed by making a tooth width of the tooth  694   b  narrow is a space into which the second circular arc-shaped outer peripheral part  687  of the drive gear  68  is entered to structure the second lock mechanism  82  together with the drive gear  68  as described below. 
       (Structures of First Stopper Mechanism  71  and First Lock Mechanism  81 ) 
       [0055]    In the damper device  1  in this embodiment, when the drive gear  68  is turned in the first direction shown by the arrow “B 1 ”, the sector gear  69  is turned in the direction shown by the arrow “B 2 ” and the baffle  4  is turned in a closing direction. On the other hand, when the drive gear  68  is turned in the second direction shown by the arrow “A 1 ”, the sector gear  69  is turned in the direction shown by the arrow “A 2 ” and the baffle  4  is turned in an open direction. 
         [0056]    In this embodiment, the first stopper mechanism  71  which restricts a movable range in the first turning direction (direction shown by the arrow “B 1 ”) of the drive gear  68  when the baffle  4  is turned in a closing direction is structured between the drive gear  68  and the case  3 . Further, the first lock mechanism  81  is structured between the drive gear  68  and the sector gear  69  by which, in a state that the first stopper mechanism  71  is operated, turning of the sector gear  69  in a direction that the baffle  4  is going to turn in an open direction (turning in a direction shown by the arrow “A 2 ”) is prevented. 
         [0057]    Specifically, as shown in  FIG. 3 ,  FIGS. 4( a ), 4( b ) and 4( c )  and  FIG. 5 , when the drive gear  68  is turned in the first direction shown by the arrow “B 1 ”, the protruded part  689  of the drive gear  68  is abutted with the stopper protruded part  39  of the case  3  and further turning of the drive gear  68  is prevented. In this manner, the first stopper mechanism  71  is structured. 
         [0058]    In this embodiment, in a plurality of the teeth  694  of the sector gear  69 , a portion of the tooth  694   a  which is located at the most end position in the direction shown by the arrow “A 2 ” is formed such that a dimension of the portion of the tooth  694   a  in the axial line direction is narrowed. Therefore, the first circular arc-shaped outer peripheral part  686  which is formed at an adjacent position in the second direction (arrow “A 1 ” direction) with respect to the partially toothless gear  682  of the drive gear  68  and is formed so as to have the same diameter and concentrically with a tooth tip circle of the partially toothless gear  682  is entered into the narrowed portion of the tooth  694   a  and the sector gear  69  is restricted and thus turning in the direction shown by the arrow “A 2 ” of the sector gear  69  is prevented. In this manner, the first lock mechanism  81  is structured. In this case, it may be structured that the first circular arc-shaped outer peripheral part  686  is extended in a radial direction to a position where turning of the sector gear  69  is not disturbed. 
       (Structures of Second Stopper Mechanism  72  and Second Lock Mechanism  82 ) 
       [0059]    In this embodiment, the second stopper mechanism  72  which restricts a movable range in the second turning direction (direction shown by the arrow “A 1 ”) of the drive gear  68  when the baffle  4  is turned in an open direction is structured between the drive gear  68  and the case  3 . Further, the second lock mechanism  82  is structured between the drive gear  68  and the sector gear  69  by which the baffle  4  is restricted in a stopped state at a front position before the second stopper mechanism  72  is operated. 
         [0060]    Specifically, in a state shown in  FIG. 3 ,  FIGS. 4( a ), 4( b ) and 4( c )  and  FIG. 5 , when the drive gear  68  is turned in the second direction shown by the arrow “A 1 ”, the protruded part  688  of the drive gear  68  is abutted with the stopper protruded part  39  of the case  3  and further turning of the drive gear  68  is prevented. In this manner, the second stopper mechanism  72  is structured. 
         [0061]    In this embodiment, in a plurality of the teeth  694  of the sector gear  69 , portions of the second and the third teeth  694   b  from the most end tooth in a direction shown by the arrow “B 2 ” are narrowed in a dimension in the axial line direction. Therefore, the second circular arc-shaped outer peripheral part  687  which is formed at an adjacent position in the first direction (arrow “B 1 ” direction) with respect to the partially toothless gear  682  of the drive gear  68  and is formed so as to have the same diameter and concentrically with the tooth tip circle of the partially toothless gear  682  is entered into the narrowed portions of the second and the third teeth  694   b  and the sector gear  69  is restricted and thus turning in the direction shown by the arrow “A 2 ” and the direction shown by the arrow “B 2 ” of the sector gear  69  is prevented. In this manner, the second lock mechanism  82  which restricts the baffle  4  in a stopped state is structured at a front position before the second stopper mechanism  72  is operated. In this case, it may be structured that the second circular arc-shaped outer peripheral part  687  is extended in a radial direction to a position where turning of the sector gear  69  is not disturbed. 
       (Detailed Structure of Partially Toothless Gear of Drive Gear) 
       [0062]      FIGS. 6( a ) and 6( b )  are explanatory views showing a tooth face of the tooth  682   c  on the most first circular arc-shaped outer peripheral part  686  side in the partially toothless gear  682  of the drive gear  68  in the damper device  1 .  FIG. 6( a )  is an explanatory enlarged view showing the tooth  682   c  on the most first circular arc-shaped outer peripheral part  686  side of the drive gear  68  and the like in the damper device  1  to which the disclosure is applied.  FIG. 6( b )  is an explanatory enlarged view showing a tooth  682   c  of the most first circular arc-shaped outer peripheral part  686  side of the drive gear  68  and the like in a damper device in accordance with a reference example.  FIGS. 6( a ) and 6( b )  show states that the baffle  4  is located in an open state and the sector gear  69  is restricted by the first circular arc-shaped outer peripheral part  686  of the drive gear  68 , i.e., by the first lock mechanism  81 . 
         [0063]      FIG. 7  is a graph showing an angular variation of a common normal line of the tooth  682   c  of the drive gear  68  and the tooth  694   c  of the sector gear  69  accompanied with turning of the drive gear  68  in the damper device  1 .  FIG. 6  shows variations of angles of common normal lines of the teeth  682   c  and  682   f  on the most first circular arc-shaped outer peripheral part  686  sides of the drive gears  68  and the teeth  694   c  and  694   f  of the sector gears  69  having been pressure-contacted and restricted by the first circular arc-shaped outer peripheral parts accompanied with turning of the drive gear  68 . Further, in  FIG. 7 , the position of a common normal line in a state “P 0 ” that the sector gear  69  is restricted is determined as 0° (reference), and an angular variation of the common normal line is shown during the drive gear  68  is turned to the state “P 7 ” from the state “P 0 ” that the sector gear  69  is restricted. Further, in  FIG. 7 , the solid line “G 1 ” indicates a case that the disclosure is applied and the solid line “G 2 ” indicates a case of the reference example. 
         [0064]    In the first lock mechanism  81  described with reference to  FIG. 3  and the like, in this embodiment, as shown in  FIG. 6( a ) , in a plurality of the teeth  682   a  structuring the partially toothless gear  682  of the drive gear  68 , the tooth  682   c  on the most first circular arc-shaped outer peripheral part  686  side is formed so that a curvature of a first tooth face  682   c   1  on an opposite side to the first circular arc-shaped outer peripheral part  686  side is set to be smaller than a curvature of a second tooth face  682   c   2  on the first circular arc-shaped outer peripheral part  686  side. Further, in a tooth face of the tooth  682   c , an outer peripheral portion  682   c   3  located on the most outer peripheral side structures a curved face which is continuously connected with the first tooth face  682   c   1  and an inflection part exists only between the outer peripheral portion  682   c   3  and the second tooth face  682   c   2 . Therefore, a continuous curved face is formed from a side of the first tooth face  682   c   1  to the second tooth face  682   c   2 . Therefore, as described below while comparing with the reference example shown in  FIG. 6( b ) , in a case that the drive gear  68  is turned in a direction shown by the arrow “A 1 ” from a state that the sector gear  69  is restricted by the first lock mechanism  81  and the baffle  4  is driven in an open direction, even when the baffle  4  is subjected to an urging force caused by repulsion of the elastic member  49 , the sector gear  69  is not turned rapidly. 
         [0065]    Further, in the tooth face of the tooth  682   c , the outer peripheral portion  682   c   3  which is located on the most outer peripheral side structures a continuous curved face with the first circular arc-shaped outer peripheral part  686 . Therefore, a continuous curved face is formed from a side of the first tooth face  682   c   1  to the first circular arc-shaped outer peripheral part  686  through the second tooth face  682   c   2 . Therefore, as described below while comparing with the reference example shown in  FIG. 6( b ) , in a case that the drive gear  68  is turned in a direction shown by the arrow “A 1 ” from a state that the sector gear  69  is restricted by the first lock mechanism  81  and the baffle  4  is driven in an open direction, even when the baffle  4  is subjected to an urging force caused by repulsion of the elastic member  49 , the sector gear  69  is not turned rapidly. 
         [0066]    On the other hand, in the reference example, as shown in  FIG. 6( b ) , in a plurality of teeth  682   a  structuring the partially toothless gear  682  of the drive gear  68 , the tooth  682   f  on the most first circular arc-shaped outer peripheral part  686  side is formed so that a curvature of a first tooth face  682   f   1  on an opposite side to the first circular arc-shaped outer peripheral part  686  side and a curvature of a second tooth face  682   f   2  on the first circular arc-shaped outer peripheral part  686  side are equal to each other. Therefore, inflection parts are existed between an outer peripheral portion  682   f   3  located on the most outer peripheral side and the first tooth face  682   f   1  and between the outer peripheral portion  682   f   3  and the second tooth face  682   f   2 . 
         [0067]    According to this structure, in a state that the sector gear  69  is restricted by the first lock mechanism  81 , when the drive gear  68  is turned in a direction shown by the arrow “A 1 ” and the baffle  4  is driven in an open direction, the sector gear  69  is turned rapidly. In other words, when the baffle  4  is driven in an open direction, the tooth  682   f  of the drive gear  68  rides over the second tooth  694   f  of the sector gear  69 . In this case, the baffle  4  is subjected to repulsive force of the elastic member  49  and thus the sector gear  69  is urged in an open direction shown by the arrow “A 2 ”. Therefore, the tooth  682   f  of the drive gear  68  intermittently collides with the second tooth  694   f  of the sector gear  69  and the sector gear  69  is turned rapidly. Meanwhile, as shown by the solid line “G 2 ” in  FIG. 7 , a direction of the common normal line of the tooth  682   f  and the tooth  694   f  is largely varied. Therefore, an abnormal noise is occurred due to a collision of the tooth  682   f  with the tooth  694   f  and/or a collision between other members. 
         [0068]    Also in this embodiment, in a state that the sector gear  69  is restricted by the first lock mechanism  81 , when the drive gear  68  is turned in a direction shown by the arrow “A 1 ” and the baffle  4  is driven in an open direction, the tooth  682   c  of the drive gear  68  rides over the second tooth  694   c  of the sector gear  69 . However, in this embodiment, a curvature of the first tooth face  682   c   1  of the tooth  682   c  on an opposite side to the first circular arc-shaped outer peripheral part  686  side is set to be smaller than a curvature of the second tooth face  682   c   2  on the first circular arc-shaped outer peripheral part  686  side and a continuous curved face is formed from the side of the first tooth face  682   c   1  to the second tooth face  682   c   2 . Therefore, even when the baffle  4  is subjected to repulsive force of the elastic member  49  and the sector gear  69  is urged in an open direction shown by the arrow “A 2 ”, the tooth  682   c  of the drive gear  68  is continuously contacted with the second tooth  694   c  of the sector gear  69  in substantially the same state and thus the sector gear  69  is turned gradually. Meanwhile, as shown by the solid line “G 1 ” in  FIG. 7 , a direction of the common normal line of the tooth  694   c  and the tooth  682   c  is not varied largely. Therefore, an abnormal noise is restrained from being occurred due to a collision of the tooth  682   c  with the tooth  694   c  and/or a collision between other members. 
         [0000]    (Operation and Principal Effects in this Embodiment) 
         [0069]    As described above, in the damper device  1  in this embodiment, the first stopper mechanism  71  which restricts a movable range of the drive gear  68  in a first turning direction (direction shown by the arrow “B 1 ”) when the baffle  4  is turned in a closing direction is structured between the drive gear  68  and the case  3 . Therefore, according to this embodiment, the position where the first stopper mechanism  71  is operated is set as a starting point and, when the baffle is driven in either direction of an open direction and a closing direction, a drive signal having the same number of steps is supplied to the stepping motor  60 . Therefore, in a case that the opening part  210  of the frame  2  is set in a closed state by the baffle  4 , even when the baffle  4  is further driven in a closing direction from a state that the baffle  4  is abutted with the frame  2 , step-out of the stepping motor  60  is hard to be occurred because the number of steps is set at the time point when the first stopper mechanism  71  is operated as the starting point. Accordingly, a situation that gears of the gear train  65  are momentarily reversed is hard to be occurred due to step-out and thus an abnormal noise caused by a collision between the teeth can be restrained. 
         [0070]    Further, in this embodiment, in a case that the baffle  4  sets the opening part  210  in a closed state, a portion of the baffle  4  which contacts with frame  2  is made of the elastic member  49 , and the elastic member  49  is elastically deformed by contacting with the frame  2  in a state that the opening part  210  is closed by the baffle  4 . Therefore, the opening part  210  can be surely set in a closed state. In this case, when the opening part  210  of the frame  2  is to be set in a closed state by the baffle  4 , the seal plate part  26  is pressed and entered into the elastic member  49  and thus, the baffle  4  is further driven in a closing direction from a state that the baffle  4  is abutted with the frame  2 . Even in this structure, according to this embodiment, the number of steps is set with the time point when the first stopper mechanism  71  is operated as the starting point and thus an entering degree of the seal plate part  26  into the elastic member  49  is restricted by the first stopper mechanism  71 . Therefore, the step-out of the stepping motor  60  is hard to be occurred. 
         [0071]    Further, the first lock mechanism  81  which prevents turning of the sector gear  69  in a direction that the baffle  4  is going to turn in an open direction in a state that the first stopper mechanism  71  is operated is structured between the drive gear  68  and the sector gear  69 . Therefore, even when force for turning the baffle  4  in an open direction is acted by fluid pressure of cold air in a state that the baffle  4  is located in a closing posture, turning of the sector gear  69  is prevented by the first lock mechanism  81 . Therefore, the baffle  4  is hard to be displaced from the state in the closing posture. Further, even when the baffle  4  is going to be turned in a closing direction, turning of the sector gear  69  is prevented by the first stopper mechanism  71  through the drive gear  68 . Therefore, it is sufficient that the first lock mechanism  81  prevents turning of the sector gear  69  toward one side. Accordingly, in the sector gear  69 , it is sufficient that a dimension in an axial line direction of the tooth  694   a  located on the most end side in a circumferential direction is narrowed and thus a portion of the sector gear required to structure the first lock mechanism  81  can be made narrow. As a result, the size of the sector gear  69  can be reduced. 
         [0072]    In this embodiment, in order to structure the first lock mechanism  81 , in a plurality of the teeth  682   a  structuring the partially toothless gear  682  of the drive gear  68 , the tooth  682   c  on the most first circular arc-shaped outer peripheral part  686  side is formed so that a curvature of the first tooth face  682   c   1  on an opposite side to the first circular arc-shaped outer peripheral part  686  side is set to be smaller than a curvature of the second tooth face  682   c   2  on the first circular arc-shaped outer peripheral part  686  side and a continuously curved face is formed from the side of the first tooth face  682   c   1  to the second tooth face  682   c   2 . Therefore, in a state that the sector gear  69  is restricted by the first lock mechanism  81 , when the drive gear  68  is turned in a direction shown by the arrow “A 1 ” and the baffle  4  is driven in an open direction, even when the baffle  4  is subjected to an urging force due to repulsion of the elastic member  49 , the tooth  682   c  of the drive gear  68  is continuously contacted with the second tooth  694   c  of the sector gear  69  in substantially the same state and thus the sector gear  69  is turned gradually. Accordingly, an abnormal noise is restrained from occurring due to a collision of the tooth  682   c  with the tooth  694   c  and/or a collision between other members. 
         [0073]    Further, the second stopper mechanism  72  is structured which restricts a movable range of the drive gear  68  in the second turning direction when the baffle  4  is turned in an open direction. The movable range of the baffle  4  is set from the position where the first stopper mechanism  71  is operated to the front position before the second stopper mechanism  72  is operated by the number of steps of the stepping motor  60  with the first stopper mechanism  71  as the starting point. Therefore, even in a case that the baffle  4  is running out of control in an open direction, the run-away of the baffle  4  can be prevented by the second stopper mechanism  72 . Further, normally, the movable range of the drive gear  68  is set at the front position before the second stopper mechanism  72  is operated and thus a situation that the second stopper mechanism  72  is operated to cause step-out of the stepping motor  60  is hard to be occurred. 
         [0074]    Further, the second lock mechanism  82  which holds the sector gear  69  in a stopped state at the front position before the second stopper mechanism  72  is operated is structured between the drive gear  68  and the sector gear  69 . Therefore, the baffle  4  in the open posture can be restrained from flapping due to fluid pressure. 
       Other Embodiments 
       [0075]    Although the disclosure has been shown and described with reference to a specific embodiment, various changes and modifications will be apparent to those skilled in the art from the teachings herein. For example, in the embodiment described above, the disclosure is applied to the lock mechanism which holds the baffle  4  in a closed position, but the disclosure may be applied to a lock mechanism which holds the baffle  4  in an open position. Further, for example, a structure may be adopted that the baffle  4  is urged by a tension coil spring or the like as the lock mechanism which holds the baffle  4  in an open posture. Further, the damper device  1  in the embodiment described above is used in a refrigerator but the disclosure is not limited to a damper device used in a refrigerator. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               1  damper device 
               2  frame 
               210  opening part 
               3  case 
               32  body part 
               321 - 324  side plate part 
               39  stopper protruded part 
               4  baffle 
               49  elastic member 
               6  drive mechanism 
               60  stepping motor 
               601  motor pinion 
               605  main body part of stepping motor 
               65  gear train 
               66  first gear 
               660  rotation shaft of first gear 
               67  second gear 
               68  drive gear 
               682  partially toothless gear 
               682   c  tooth on the most first circular arc-shaped outer peripheral part side 
               682   c   1  first tooth face 
               682   c   2  second tooth face 
               686  first circular arc-shaped outer peripheral part 
               687  second circular arc-shaped outer peripheral part 
               688 ,  689  protruded part 
               69  sector gear 
               691  output shaft 
               694 ,  694   a ,  694   b  tooth 
               71  first stopper mechanism 
               72  second stopper mechanism 
               81  first lock mechanism 
               82  second lock mechanism 
             “A”, “A 1 ”, “A 2 ” turning in open direction 
             “B”, “B 1 ”, “B 2 ” turning in closing direction