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CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     The present invention claims priority under 35 U.S.C. §119 to Japanese Application No. 2004-242758 filed Aug. 23, 2004 and Japanese Application No. 2005-33624 filed Feb. 9, 2005, which are incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     An embodiment of the present invention may relate to a door opening and closing assisting device for assisting closing of a door in a refrigerator or the like.  
       BACKGROUND OF THE INVENTION  
       [0003]     A conventional door opening and closing assisting device for performing opening and closing of a door in a refrigerator or the like surely is provided with a coil spring which is arranged so as to be laid across the main body of the refrigerator and the door, and the door is urged in the closing direction by the coil spring (see, for example, Japanese Patent Laid-Open No. Sho 57-73384).  
         [0004]     In the conventional door opening and closing assisting device, when the urging force of the coil spring is always applied to the door, foods are not be easily put in or taken out from the refrigerator. Therefore, a lever member is required to be utilized to detect and adjust the position of the door and the timing for when the urging force is applied to the door. However, in the case that the coil spring and a timing adjusting mechanism are dividedly disposed in the main body of the refrigerator and the door, the positional relationship between a member disposed on the main body of the refrigerator and a member disposed on the door are required to be arranged with a high degree of accuracy. Therefore, time and effort are required for their assembly and the timing for when the urging force is applied to the door is easily varied.  
       SUMMARY OF THE INVENTION  
       [0005]     In view of the problems described above, an embodiment of the present invention may advantageously provide a door opening and closing assisting device whose assembly is easily performed and in which a timing for when an urging force is applied to a door is easily set.  
         [0006]     Thus, according to an embodiment of the present invention, there may be provided a door opening and closing assisting device for assisting a closing operation of a door which is connected to a main body of an apparatus through a hinge mechanism to open or close an aperture part formed in the main body of the apparatus. The door opening and closing assisting device includes a lever member which swings in cooperation with an opening and closing operation of the door, a first spring member for generating an urging force which is elastically deformed by a swing motion of the lever member when the door is swung in an open direction and which urges the door by an elastic return force of the first spring member in a closing direction through the lever member, and a switching mechanism which mechanically connects the lever member to the first spring member while the door is located between a completely closed position of the door and a half-opened position where the door is swung by a prescribed angle in an open direction from the completely closed position and which disconnects the mechanical connection between the lever member and the first spring member while the first spring member is maintained in a state where the first spring member is forcibly urged and elastically deformed when the door is located at a further opened position from the half-opened position. All of the lever member, the first spring member and the switching mechanism are arranged on one of the door and the main body of the apparatus.  
         [0007]     In accordance with an embodiment of the present invention, when the door is opened, the first spring member for generating an urging force is forcibly urged and elastically deformed in a region where the door is swung from the completely closed position to the half-opened position. In addition, when the door is further opened, the switching mechanism disconnects the mechanical connection between the lever member and the first spring member while the first spring member is maintained in a state where the first spring member is forcibly urged and elastically deformed. Therefore, in the state where the door is widely opened, foods can be easily put in and taken out because an urging force is not applied to the door. Further, in the case that the door is closing, when the door reaches to the half-opened position, the switching mechanism connects the lever member and the first spring member in a mechanical manner and thus the urging force of the first spring member is applied to the door. Therefore, the door can be easily and surely closed. In addition, in an embodiment of the present invention, all of the lever member, the first spring member and the switching mechanism are mounted on one of the door and the main body of the apparatus. Therefore, the switching mechanism that adjusts the timing when the position of the door is detected to apply the urging force to the door is constructed on only one side of the door and the main body of the apparatus, and thus assembly can be performed easily and the timing at which the urging force is applied to the door is easily set.  
         [0008]     In accordance with an embodiment of the present invention, the lever member, the first spring member for generating an urging force and the switching mechanism are arranged on the main body of the apparatus. According to the construction described above, increase of the size and weight of the door is avoided.  
         [0009]     In accordance with an embodiment of the present invention, the switching mechanism includes a first cam part for transmitting an opening and closing operation which is formed in the lever member, a relay member which is displaced by the first cam part to cause the first spring member to be deformed elastically while the door is located between the completely closed position and the half-opened position and which is capable of transmitting an elastic return force generated by the elastically deformed first spring member to the lever member through the first cam part to the door. The switching mechanism also includes a stopper mechanism which permits the disconnection of the mechanical connection between the first cam part and the relay member when the door is located at a further opened position from the half-opened position. The stopper mechanism keeps the first spring member in a state where the first spring member is forcibly urged and elastically deformed by restricting the relay member while the door is located at a further opened position from the half-opened position.  
         [0010]     In accordance with an embodiment of the present invention, the stopper mechanism includes a stopper member which keeps the first spring member from generating an urging force on the lever member in the state where the first spring member is forcibly urged and elastically deformed by restricting the relay member when the door is located at a further opened position from the half-opened position, and a second spring member for pressing the stopper member for displacing the stopper member to a position where the relay member is restricted.  
         [0011]     In accordance with an embodiment of the present invention, the stopper member is swung around a common rotation center axis to the lever member and is displaced to the position where the relay member is restricted.  
         [0012]     In accordance with an embodiment of the present invention, the lever member is provided with a second cam part for pressing the relay member which presses the relay member back to a position to enable a closing operation of the door when the stopper member restricting the relay member is displaced by an external force and releases the restriction of the relay member and the relay member moves to a position obstructing the closing operation of the door.  
         [0013]     In this case, the second cam part for pressing the relay member is preferably formed so as to press the relay member back to a position where the relay member is restricted by the stopper member and the stopper member is returned to a state which is capable of restricting the relay member by the second spring member for pressing the stopper member being pressed.  
         [0014]     In accordance with an embodiment of the present invention, a damper device is preferably provided, which is mechanically connected to the relay member for generating a load when the door is swung in a closing direction. According to the construction described above, the door can be prevented from closing rapidly.  
         [0015]     In accordance with an embodiment of the present invention, it is preferable that the lever member causes the relay member to swing in a direction in which the damper device generates a load when the door is swung in the closing direction. According to the construction described above, even when the door is closed with a large force, since the lever member causes the relay member to swing directly, the door can be prevented from closing rapidly by the operation of the damper device.  
         [0016]     In accordance with an embodiment of the present invention, a shutter member is provided which is moved to cover a portion between the door and the main body of the apparatus in cooperation with the lever member when the door is swung in an open direction.  
         [0017]     In accordance with an embodiment of the present invention, a transmission mechanism for interlocking the door with the lever member includes a roller and a guide part that guides the roller. According to the construction described above, the swing motion of the door can be smoothly transmitted to the lever member.  
         [0018]     As described above, in accordance with an embodiment of the present invention, the first spring member for generating an urging force is forcibly urged and elastically deformed in a region where the door is swung from the completely closed position to the half-opened position when the door is opened and, when the door is further opened, the switching mechanism disconnects the mechanical connection between the lever member and the first spring member while the first spring member is maintained in a state where the first spring member is forcibly urged and elastically deformed. Therefore, in the state where the door is widely opened, foods can be easily put in and taken out because an urging force is not applied to the door. Further, in the case that the door is closing, when the door reaches to the half-opened position, the switching mechanism causes the lever member and the first spring member to connect in a mechanical manner and thus the urging force of the first spring member is applied to the door. Therefore, the door can be easily and surely closed. In addition, in an embodiment of the present invention, all of the lever member, the first spring member and the switching mechanism are mounted on one of the door and the main body of the apparatus. Therefore, since the switching mechanism for adjusting the timing when the position of the door is detected to apply the urging force to the door is constructed only on one side of the door and the main body of the apparatus, assembly can be performed easily and the timing at which the urging force is applied to the door is easily set. As a result, a door can be surely closed in a double swinging doors type of refrigerator or the like.  
         [0019]     Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrate, by way of example, various features of embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which:  
         [0021]      FIG. 1  is an explanatory view showing a refrigerator in which a door opening and closing assisting device in accordance with an embodiment of the present invention is mounted.  
         [0022]      FIG. 2 (A) is an explanatory plan view showing the structure of a door opening and closing assisting device in accordance with an embodiment of the present invention,  FIG. 2 (B) is its longitudinal sectional view,  FIG. 2 (C) is a sectional view showing a lever member, FIG.  2 (D) is a sectional view showing a first spring member for generating an urging force, and  FIG. 2 (E) is an explanatory view showing an urging force adjustment part.  
         [0023]      FIG. 3 (A) is a plan view showing a lever member which is used in a door opening and closing assisting device in accordance with an embodiment of the present invention,  FIG. 3 (B) is a plan view showing the first spring member for generating an urging force and the like,  FIG. 3 (C) is an explanatory view showing a stopper mechanism, and  FIG. 3 (D) is an explanatory view showing a shutter plate.  
         [0024]      FIG. 4  is a plan view showing the state where the door is at a half-opened position in a door opening and closing assisting device in accordance with an embodiment of the present invention.  
         [0025]      FIG. 5  is a plan view showing the state where the door is at a full-opened position in a door opening and closing assisting device in accordance with an embodiment of the present invention.  
         [0026]      FIG. 6  is an explanatory view showing the state where the restriction of a relay member is released by a stopper member in a door opening and closing assisting device in accordance with an embodiment of the present invention.  
         [0027]     FIGS.  7 (A) and  7 (B) are explanatory plan views showing the effect of the door opening and closing assisting device shown in  FIG. 6 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     Embodiments of the present invention will be described below with reference to the accompanying drawings.  
         [0029]      FIG. 1  is an explanatory view showing a refrigerator in which a door opening and closing assisting device in accordance with an embodiment of the present invention is mounted.  FIG. 2 (A) is an explanatory plan view showing the structure of a door opening and closing assisting device in accordance with an embodiment of the present invention,  FIG. 2 (B) is its longitudinal sectional view,  FIG. 2 (C) is a sectional view showing a lever member,  FIG. 2 (D) is a sectional view showing a first spring member for generating an urging force, and  FIG. 2 (E) is an explanatory view showing an urging force adjustment part.  FIG. 3 (A) is a plan view showing a lever member which is used in a door opening and closing assisting device in accordance with an embodiment of the present invention,  FIG. 3 (B) is a plan view showing the first spring member for generating an urging force and the like,  FIG. 3 (C) is an explanatory view showing a stopper mechanism, and  FIG. 3 (D) is an explanatory view showing a shutter plate. In the description below, the position of a door shown in  FIG. 2 (A) is a completely closed position, the position shown in  FIG. 4  when the door is swung from the completely closed position by a specified angle in an open direction (counterclockwise direction) is a half-opened position, and the position shown in  FIG. 5  when the door is further swung from the half-opened position in the open direction (counterclockwise direction) is a full opened position.  
         [0030]     A refrigerator  1  shown in  FIG. 1  is provided with a refrigerator main body  3  and a pair of double swing doors  2  for opening or closing its opening part  9 . The pair of doors  2  is connected to the refrigerator main body  3  through respective hinge mechanisms  5  so as to be capable of opening or closing the opening part  9  of the refrigerator main body  3 . In the refrigerator  1  in accordance with an embodiment of the present invention, door opening and closing assisting devices  10  are respectively constructed on its upper face to assist closing operation of the pair of doors  2 .  
         [0031]     In an embodiment of the present invention, as shown in  FIG. 2 (A), a door support plate  4  is fixed on the upper face of the refrigerator main body  3  and the door  2  is supported at its tip end part through the hinge mechanism  5 . The door opening and closing assisting device  10  includes, as shown in FIGS.  2 (A) and  2 (B), a base plate  11  fixed to the upper face of the refrigerator  1  and a base plate  12  disposed oppositely to the base plate  11 . The base plates  11 ,  12  are fixed to each other with connecting shafts  25 ,  35 ,  48 ,  100  and the like.  
         [0032]     In FIGS.  2 (A) and  2 (B) and FIGS.  3 (A) through  3 (D), the door opening and closing assisting device  10  includes a lever member  20  which swings in cooperation with the opening and closing operation of the door  2 , a first spring member  40  for generating an urging force to apply the urging force to the door  2  in a closing direction, and a stopper mechanism  80  which changes to the state where the first spring member  40  and the lever member  20  are mechanically connected to each other and to the state where their connection is released. In an embodiment of the present invention, the lever member  20  and the first spring member  40  are mechanically connected through a relay member  30 . In this embodiment, a switching mechanism performing a function described later is constructed by the relay member  30  and the stopper mechanism  80 .  
         [0033]     The structure of respective members which are used in the door opening and closing assisting device  10  will be successively described below. First, as shown in FIGS.  2 (A),  2 (B) and  2 (C) and  FIG. 3 (A), the lever member  20  is constructed by a pair of plate members  201 ,  202  which are oppositely faced via a prescribed space with a plurality of connecting shafts  22 ,  23 . The lever member  20  is rotatably supported in a clockwise direction CW and in a counterclockwise direction CCW around a rotation center shaft  25  which is fixed between the base plates  11 ,  12 . The rotation center shaft  25  is disposed at a side portion of the rotation center shaft of the hinge mechanism  5  which is the rotation center of the door  2  and both the positions of the rotation center shaft  25  and the hinge mechanism  5  are displaced.  
         [0034]     The lever member  20  is provided with a base part  24  disposed on a rotation center shaft  25  side and an extended part  28  extended from the base part  24 . A support shaft  211  protrudes downward from the under face of the extended part  28 . A roller  21  is supported at a lower end portion of the support shaft  211  so as to be rotatable around the axial line of the support shaft  211 . A guide groove  8  (guide part) is formed on the upper face of the door  2  and the roller  21  of the lever member  20  is disposed in the guide groove  8  in a movable manner. Therefore, in an embodiment of the present invention, a transmission mechanism  7  for interlocking the lever member  20  with the door  2  is constructed by the guide groove  8  and the roller  21 . The base part  24  of the lever member  20  is provided with a first cam part  26  for transmitting opening and closing operation which is curved so that its radius is gradually increased and another first cam part  29  for transmitting opening and closing operation which is formed so as to be gradually increased to be a maximum radius portion from the first cam part  26 . The first cam part  26  and the other first cam part  29  are formed on the outer peripheral edge part of a portion which is apart from the rotation center shaft  25 .  
         [0035]     As shown in FIGS.  2 (A) and  2 (B) and  FIG. 3 (B), a relay member  30  constructing a switching mechanism is constructed by a pair of roughly rectangular plate members  301 ,  302  which are oppositely faced via a prescribed space with a connecting shaft. The relay member  30  is rotatably supported in the clockwise direction CW and the counterclockwise direction CCW on the rotation center shaft  35  that is fixed between the base plate  11  and the base plate  12 . A roller  31  is supported by a support shaft at one of four corner portions of the relay member  30 . The roller  31  abuts with the first cam part  26  for transmitting opening and closing operation of the lever member  20 . Further, a connecting shaft  39  of the relay member  30  which is located on the opposite side of the roller  31  with respect to the rotation center shaft  35  is formed as an operation part to the first spring member  40  described later.  
         [0036]     As shown in FIGS.  2 (A) and  2 (B) and  FIG. 3 (B), a roughly fan shaped gear  36  is fixed between the pair of plate members  301 ,  302  of the relay member  30 . An oil type of damper device  50  is disposed at a side portion of the relay member  30 . The outer teeth constructed on the outer peripheral portion of the damper device  50  engages with the teeth part  37  of the gear  36 . The damper device  50  is constructed such that a square shaft part disposed on its center side is prevented from being rotated by the base plates  11 ,  12  and its outer peripheral side is formed as a rotating part and a damper mechanism is assembled between the square shaft part and the rotating part. The damper mechanism is constructed such that a load is not applied when the rotating part on its outer peripheral side is rotated in the counterclockwise direction CCW and a load is applied when the rotating part is rotated in the clockwise direction CW. Further, in an embodiment of the present invention, a load by the damper is set to be changed in accordance with its rotation angle.  
         [0037]     As shown in  FIG. 2 (D) and  FIG. 3 (B), the first spring member  40  composed of a coil spring is disposed at a side portion of the relay member  30 . The first spring member  40  is engaged with a spring positioning shaft  48  disposed on its inner side, an urging force adjusting part  45  with which one side edge part  42  is engaged, and the connecting shaft  39  of the relay member  30  with which the other edge part  41  is abutted.  
         [0038]     As shown in  FIG. 2 (E) and  FIG. 3 (B), the urging force adjusting part  45  is constructed of an L-shaped plate and two grooves  46 ,  47  are formed on the upper face of the rising part of the urging force adjusting part  45 . Therefore, in the urging force adjusting part  45 , the urging force of the first spring member  40  can be adjusted by changing the position where the one side end part  42  of the first spring member  40  is engaged with either of two grooves  46 ,  47 .  
         [0039]     As shown in FIGS.  2 (A) and  2 (B) and  FIG. 3 (C), the stopper mechanism  80  is composed of a plate shaped stopper member  70  disposed between the pair of plate members  201 ,  202  constructing the lever member  20  and a second spring member  60  for pressing the stopper member which is constructed to press the stopper member  70  in the counterclockwise direction CCW. The stopper member  70  is rotatably supported by the rotation center shaft  25  in the clockwise direction CW and the counterclockwise direction CCW like the lever member  20 . The second spring member  60  is a leaf spring whose central portion in its longitudinal direction is supported by the connecting shaft  32  of the relay member  30  and is rotatable around the connecting shaft  32  in the clockwise direction CW and the counterclockwise direction CCW. The base end portion  61  of the second spring member  60  abuts with the center portion of the gear  36  disposed on the relay member  30  and, when the relay member  30  is rotated in the clockwise direction CW, the tip end portion  62  of the second spring member  60  presses the edge part on the clockwise direction CW side of the stopper member  70 .  
         [0040]     In an embodiment of the present invention, when the radius of the other first cam part  29  which is adjacent to the first cam part  26  of the lever member  20  in the clockwise direction CW is set to be R 3  (see  FIG. 3 (A)), the radius of a shallow recessed part  71  which is formed on the outer peripheral portion of the stopper member  70  is set to be R 1  (see  FIG. 3 (C)), and the radius of a circular arc part  73  which is adjacent to the recessed part  71  in the counterclockwise direction CCW is set to be R 2  (see  FIG. 3 (C)), the relationship between the R 1 , R 2  and R 3  is set to be R 1 &lt;R 2 &lt;R 3 . Further, a protruded part  72  is formed on the portion which is adjacent to the recessed part  71  in the clockwise direction CW.  
         [0041]     As shown in FIGS.  2 (A) and  2 (B) and  FIG. 3 (D), in the door opening and closing assisting device  10  in accordance with an embodiment of the present invention, a fan-shaped shutter plate  90  is disposed between the lever member  20  and the base plate  12 . The shutter plate  90  is rotatably supported around the rotation center shaft  25  in the clockwise direction CW and in the counterclockwise direction CCW like the stopper member  70  and the lever member  20 . The shutter plate  90  is provided with a protruded part  92  formed near its rotation center and a protruded part  93  formed on its outer peripheral circular arc portion. The height dimensions of the protruded parts  92 ,  93  are set to be capable of abutting with the lever member  20 . Therefore, when the lever member  20  is swung in the counterclockwise direction CCW, the base part  24  of the lever member  20  abuts with the protruded part  92  and the shutter plate  90  is swung in the counterclockwise direction CCW. On the contrary, when the lever member  20  is swung in the clockwise direction CW, the center side portion of the extended part  28  of the lever member  20  abuts with the protruded part  93  and the shutter plate  90  is swung in the clockwise direction CW. The width in the rotational direction between the protruded parts  92 ,  93  of the shutter plate  90  is set to be larger than the width in the rotational direction of the lever member  20  and thus the shutter plate  90  interlocks with the lever member  20  later than the operation of the lever member  20 .  
         [0042]      FIG. 4  is a plan view showing the state where the door is at a half-opened position and  FIG. 5  is a plan view showing the state where the door is at a full-opened position in the door opening and closing assisting device in accordance with an embodiment of the present invention.  
         [0043]     In the door opening and closing assisting device  10  and the refrigerator  1  in accordance with an embodiment of the present invention, when the door  2  is swung from the state shown in  FIG. 2 (A) to the half-opened position shown in  FIG. 4  in the counterclockwise direction CCW, the lever member  20  is swung around the rotation center shaft  25  in the counterclockwise direction CCW while the roller  21  moves in the guide groove  8 . At this time, the lever member  20  and the relay member  30  are mechanically connected to each other through the first cam part  26  and the roller  31 . Therefore, when the lever member  20  swings, the roller  31  moves along the first cam part  26  and the relay member  30  swings around the rotation center shaft  35  in the clockwise direction CW. As a result, the other edge part  41  of the first spring member  40  is pressed by the connecting shaft  39  of the relay member  30  and the first spring member  40  is forcibly urged and elastically deformed. At the same time, the outer peripheral portion of the damper device  50  is rotated by the gear  36  in the counterclockwise direction CCW but the damper device  50  does not generate a load during the rotation in this counterclockwise direction.  
         [0044]     The base end portion of the second spring member  60  for pressing the stopper member is pressed by the gear  36  and is swung around the connecting shaft  32  in the clockwise direction CW. Therefore, the tip end portion  62  of the second spring member  60  presses the edge portion on the clockwise direction CW side of the stopper member  70 . As a result, the stopper member  70  is swung around the rotation center shaft  25  in the counterclockwise direction CCW so as to follow the lever member  20 . In this state, since the stopper member  70  abuts with the connecting shaft  23  of the lever member  20 , the stopper member  70  does not go ahead of the lever member  20  in the counterclockwise direction CCW.  
         [0045]     When the door is at the half-opened position shown in  FIG. 4 , the roller  31  of the relay member  30  is fitted into the recessed part  71  formed on the outer peripheral portion of the stopper member  70  by the other first cam part  29  of the lever member  20 . The shutter member  90  has not abutted with the lever member  20  until this state and thus the shutter member  90  does not move as shown in  FIG. 2 (A) and  FIG. 4 .  
         [0046]     Next, when the door  2  is further swung from the half-opened position shown in  FIG. 4  to the full-opened position shown in  FIG. 5  in the counterclockwise direction CCW, the lever member  20  is further swung in the counterclockwise direction CCW around the rotation center shaft  25  while the roller  21  moves in the guide groove  8 . In this case, the other first cam part  29  of the lever member  20  moves away from the roller  31  of the relay member  30  and the roller  31  is fitted into the recessed part  71  and abuts with the protrusion part  72  which are formed on the outer peripheral portion of the stopper member  70 . In the state where the roller  31  of the relay member  30  is fitted into the recessed part  71  of the stopper member  70 , the forces applied to the relay member  30  and the stopper member  70  are in an equilibrium state. Therefore, even when the lever member  20  is further swung in the counterclockwise direction CCW around the rotation center shaft  25 , the stopper member  70  remains to be stopped at the position shown in  FIG. 4 . Accordingly, even when the lever member  20  is further swung in the counterclockwise direction CCW around the rotation center shaft  25 , the relay member  30  is restricted by the stopper member  70  to keep its stopped state and the mechanical connection between the lever member  20  and the relay member  30  is disconnected. Consequently, the first spring member  40  is maintained in the state where the first spring member  40  is forcibly urged and elastically deformed.  
         [0047]     At this time, the outer peripheral portion of the damper device  50  is rotated in the counterclockwise direction CCW by the gear  36  but, during the rotation in this direction, the damper device  50  does not apply a load. Further, since the protruded part  92  of the shutter member  90  is pressed by the lever member  20  in the counterclockwise direction CCW, the shutter member  90  is swung in the counterclockwise direction CCW around the rotation center shaft  25  to cover a space formed between the refrigerator main body  3  and the door  2  as shown in  FIG. 5 .  
         [0048]     As described above, in an embodiment of the present invention, the stopper mechanism  80  composed of the stopper member  70  and the second spring member  60  permits the mechanical connection between the first cam part  26  and the relay member  30  while the door  2  is located between the completely closed position and the half-opened position. In addition, when the door  2  is further swung in the open direction from the half-opened position, the stopper mechanism  80  restricts the relay member  30  to keep the first spring member  40  in the forcibly urged and elastically deformed state. Accordingly, the switching mechanism which is constructed of the stopper mechanism  80  and the relay member  30  causes the lever member  20  and the first spring member  40  to connect mechanically to each other while the door  2  is located between the completely closed position and the half-opened position. Further, when the door  2  is further swung in the open direction from the half-opened position, the switching mechanism disconnects the mechanical connection between the lever member  20  and the first spring member  40  while the first spring member  40  is maintained to be forcibly urged and elastically deformed.  
         [0049]     Next, when the door  2  is swung in the clockwise direction CW from the full-opened position shown in  FIG. 5  toward the half-opened position shown in  FIG. 4 , the lever member  20  is swung in the clockwise direction CW around the rotation center shaft  25  while the roller  21  moves in the guide groove  8 . At this time, the stopper member  70  remains to be stopped at the position shown in  FIG. 5  and the relay member  30  remains to be restricted by the stopper member  70 , and thus the mechanical disconnection between the lever member  20  and the relay member  30  is maintained. Therefore, the first spring member  40  is maintained to be forcibly urged and elastically deformed.  
         [0050]     Also, when the lever member  20  is swung in the clockwise direction CW around the rotation center shaft  25 , the lever member  20  abuts with the protruded part  93  of the shutter member  90  on the way. Therefore, the shutter member  90  is swung in the clockwise direction CW together with the lever member  20  from the halfway.  
         [0051]     Next, when the door  2  is further swung in the clockwise direction CW from the half-opened position shown in  FIG. 4  to the completely closed position shown in  FIG. 2 (B), the lever member  20  is swung in the clockwise direction CW around the rotation center shaft  25  while the roller  21  moves in the guide groove  8 . In this case, the other first cam part  29  of the lever member  20  abuts with the roller  31 . In an embodiment of the present invention, the radius “R 3 ” of the other first cam part  29  is set to be R 3 &gt;R 1  as described above, and thus the other first cam part  29  receives the elastic force urged by the first spring member  40  instead of the stopper member  70 . Immediately after that, the return force of the first spring member  40  is applied through the roller  31  from the cam part  29  to the first cam part  26 . In this case, since the connecting shaft  23  of the lever member  20  presses the stopper member  70 , the stopper member  70  is swung in the clockwise direction CW together with the lever member  20 . In this manner, the roller  31  of the relay member  30  abuts with the first cam part  26  of the lever member  20  and thus the relay member  30  and the lever member  20  are mechanically connected.  
         [0052]     Therefore, after that, since the restriction of the relay member  30  is released, the first spring member  40  applies a force to swing the relay member  30  in the counterclockwise direction CCW by its elastic return force. This force is transmitted to the lever member  20  through the roller  31  and the first cam part  26 . Therefore, the elastic return force through the relay member  30  urges the door  2  in its closing direction. The urging force of the first spring member  40  is sufficiently larger than that of the second spring member  60  which apply a force to swing the lever member  20  in the counterclockwise direction CCW through the stopper member  70 . Consequently, a user is capable of closing the door  2  only by applying a little force to the door  2 . Further, the lever member  20  is capable of further turning on an inner side from the completely closed position and thus the return force of the first spring member  40  remains to apply the lever member  20 . As a result, the door  2  can be surely closed.  
         [0053]     Further, the force which swings the relay member  30  in the counterclockwise direction CCW rotates the outer peripheral portion of the damper device  50  through the gear  36  in the clockwise direction CW. During the rotation in this direction, since the damper device  50  generates a load, the door  2  is closed slowly.  
         [0054]     In addition, when the door  2  is going to be closed rapidly, the edge part  27  (see  FIG. 3 (A)) of the lever member  20  presses the connecting shaft  32  of the relay member  30  to turn the relay member  30  in the counterclockwise direction CCW. Therefore, when the door  2  is going to be closed with a large force, the lever member  20  causes the relay member  30  to swing directly and thus the transmission of a turning force of the lever member  20  and the switching mechanism (stopper mechanism  70  and relay member  30 ) is surely performed. Further, since the damper device  50  is operated, the door  2  can be prevented from closing rapidly.  
         [0055]     As described above, in the door opening and closing assisting device  10  in this embodiment of the present invention, the first spring member  40  for generating an urging force is forcibly urged and elastically deformed in a region where the door  2  is swung from the completely closed position to the half-opened position. In addition, when the door  2  is further opened, the switching mechanism (stopper mechanism  80  and relay member  30 ) disconnects the mechanical connection between the lever member  20  and the first spring member  40  while the first spring member  40  is maintained in a state to be forcibly urged and elastically deformed. Therefore, in the state where the door  2  is widely opened, foods can be easily put in and taken out because an urging force is not applied to the door  2 . Further, in the case that the door  2  is closing, when the door  2  reaches to the half-opened position, the switching mechanism causes the lever member  20  and the first spring member  40  to connect in a mechanical manner and thus the urging force of the first spring member  40  is applied to the door  2 . Therefore, the door  2  can be easily and surely closed. In addition, in this embodiment of the present invention, all the lever member  20 , the first spring member  40  and the switching mechanism are mounted on the refrigerator main body  3  side. Therefore, the timing when the urging force is applied to the door  2  can be easily adjusted with a relatively simple structure, which is different from the case in which these members are separated so as to be disposed on both the refrigerator main body  3  side and the door  2  side. Consequently, according to the door opening and closing assisting device  10  in this embodiment of the present invention, its assembly is easy and the door  2  can be easily and surely closed with a secure or preferable feeling.  
         [0056]      FIG. 6  is an explanatory view showing the state where the restriction of a relay member is released by a stopper member in a door opening and closing assisting device in accordance with another embodiment of the present invention. FIGS.  7 (A) and  7 (B) are explanatory views showing the effect of the door opening and closing assisting device shown in  FIG. 6 .  
         [0057]     In an embodiment of the present invention described above, the stopper member  70  and the second spring member  60  for pressing the stopper member are used as the stopper mechanism  80  as shown in FIGS.  2 (A) and  2 (B) and  FIG. 3 (C). However, as shown in  FIG. 6 , a stopper member  70  and another second spring member  65  for pressing the stopper member which is composed of a torsion coiled spring and urges the stopper member  70  in the counterclockwise direction CCW around the connecting part  25  may be used in an embodiment of the present invention.  
         [0058]     Further, the lever member  20  is provided with a second cam part  240  for pressing the relay member  30 , which presses back the relay member  30  to the position where the door  2  is capable of performing a closing operation when the closing operation of the door  2  is performed. According to the construction described above, as shown in  FIG. 6 , when the stopper member  70  restricting the relay member  30  is displaced by an external force to release the restriction of the relay member  30  and the relay member  30  is moved to the position where the closing operation of the door  2  is obstructed, the second cam part  240  presses back the relay member  30  to the position where the door  2  is capable of performing a closing operation. In this embodiment of the present invention, the shape of the relay member  30  and the position of the roller  31  is changed from the above-mentioned embodiment.  
         [0059]     As a comparison example, in the door opening and closing operation assisting device  1  described in  FIGS. 1 through 5 , when the door  2  is opened as shown in  FIG. 7 (A), the roller  31  of the relay member  30  is restricted by the stopper member  70  so that the door  2  is not urged in the closing direction. In this state, when the stopper member  70  is swung in the clockwise direction CW by an external force applied to the stopper member  70  in the direction as shown by the arrow “A”, the restriction of the roller  31  of the relay member  30  by the stopper member  70  is released. As a result, the relay member  30  is swung in the counterclockwise direction CCW around the connecting shaft  35  and the roller  31  is displaced in the direction as shown by the arrow “B” to reach to the state as shown in  FIG. 7 (B). In this state, when the door  2  is closed, the edge part  27  of the lever member  20  interferes with the roller  31  and the closing operation of the door  2  is obstructed. However, in this embodiment of the present embodiment, as shown in  FIG. 6 , the second cam part  240  for pressing the relay member is formed in the lever member  20 . Therefore, even when the roller  31  of the relay member  30  is displaced to the position where the closing operation of the door  2  is obstructed, the second cam part  240  pushes the roller  31  to make the relay member  30  swing in the direction shown by the arrow “C” with a relatively stronger force which is applied to the door  2  in the closing direction. As a result, the roller  31  of the relay member  30  is moved to the position where the closing operation of the door  2  is not obstructed. Further, the stopper member  70  is pressed by the other second spring member  65  to be swung in the counterclockwise direction CCW around the connecting shaft  25 . Therefore, the roller  31  of the relay member  30  fits into the recessed part  71  and the state where the roller  31  of the relay member  30  is restricted is returned. Accordingly, after that, the closing operation of the door  2  can be performed without a problem and, at this time, the urging force of the first spring member  40  is applied to the door  2  through the relay member  30  in the closing direction.  
         [0060]     In the embodiment of the present invention described above, the first spring member  40  for generating an urging force is constructed of a torsion coiled spring. However, a spiral spring or a compression spring may be used. Further, the second spring member  60  for pressing the stopper member is composed of a leaf spring but a torsion coil spring or a tension coil spring may be used. An air damper device may be used as the damper device.  
         [0061]     In the embodiment of the present invention described above, the lever member  20 , the first spring member  40  and the switching mechanism (stopper mechanism  80  and relay member  30 ) are unitized and constructed on the refrigerator main body  3  side. However, these members may be disposed on the door  2  side. Further, in the embodiment of the present invention described above, the door opening and closing assisting device  10  is applied to a double swinging doors type of refrigerator. However, the present invention may be applied to a refrigerator with a single swing door or other apparatuses.  
         [0062]     While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.  
         [0063]     The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Summary:
An embodiment of the apparatus relates to a door opening and closing assisting device comprising: a spring force to urge the door in a closed direction when the door is half-opened or less and supplies no closing force when the door is more than half-opened. The assisting device is housed either in the door or the main body. The method relates to assisting in opening and closing a door comprising: elastically deforming a spring in response to the door being opened to a half-opened position; disconnecting the spring force if the door is more than half-opened and reconnecting the spring force to the door when the door is half-opened or less.