Patent Publication Number: US-2009236863-A1

Title: Electric door latch apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2008-074990, filed on Mar. 24, 2008, the entire contents of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an electric door latch apparatus. 
     BACKGROUND 
     According to a known electric door latch apparatus, for example, disclosed in JP2001-311337A, an operational knob for operating a manual operation portion is exposed on a vehicle interior wall surface (door trim) of a door (See paragraph [0026], FIGS. 1-2). With the construction of the known electric door latch apparatus disclosed in JP2001-311337A) because the operational knob is provided at a position to which a passenger&#39;s hand can relatively readily reach and the operational knob is always in an operable state, a state is unintentionally switched to a door openable state by an inappropriate operation of the operational knob, for example, by a child&#39;s mischief even in a normally operated state in which the state can be switched by an electric activation. In order to countermeasure the forgoing problem, according to a known electric door latch apparatus disclosed in JP2006-45893A (see paragraph [0023], FIG. 1), an operational lever connected to a manual operation portion is arranged under a seat, and further, the operational lever is covered by a cover member when a seat is not occupied. 
     Notwithstanding the construction of the known electric door latch apparatus disclosed in JP2006-45893A, because the operational lever is exposed to the vehicle compartment under the seat when the seat is occupied, inappropriate operations of the operational lever can still not be prevented securely. On the contrary, in a case where the operational lever actually needs to be operated because the electric door latch apparatus becomes electrically inoperable, an operator has to look under the seat or has to grope for the operational lever under the seat. Thus, the construction of the known electric door latch apparatus disclosed in JP2006-45893A is inferior to the known electric door latch apparatus disclosed in JP2001-311337A in terms of a level of visibility. 
     A need thus exists for an electric door latch apparatus which is not susceptible to the drawback mentioned above. 
     SUMMARY OF THE INVENTION 
     In light of the foregoing, the present invention provides an electric door latch apparatus, which includes a manual operation portion adapted to be mounted on a vehicle door and configured to be switched between a closed door retaining state in which the vehicle door is retained at a closed position and a door openable state in which the vehicle door is openable by an electric actuation, the manual operation portion being switched from the closed door retaining state to the door openable state by a manual operation in an electrically inoperable condition, and the manual operation portion positioned within the vehicle door and including a tool fitting hole on a surface thereof facing a vehicle compartment side wall portion of the vehicle door. The manual operation portion is configured to be rotated by fitting a predetermined tool into the tool fitting hole via an operation hole formed penetrating through the vehicle compartment side wall portion of the vehicle door. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein: 
         FIG. 1  is a plane view of an electric door latch apparatus according to a first embodiment of the present invention; 
         FIG. 2  is a perspective view of the electric door latch apparatus according to the first embodiment of the present invention; 
         FIG. 3  is a side view of the electric door latch apparatus according to the first embodiment of the present invention; 
         FIG. 4  is a front view of a striker engagement mechanism portion in a closed door retaining state; 
         FIG. 5  is a front view of the striker engagement mechanism portion in a door openable state; 
         FIG. 6  is a cross-sectional view taken on line VI-VI in  FIG. 4 ; 
         FIG. 7  is a front view of an actuating mechanism portion in the closed door retaining state; 
         FIG. 8  is a front view of the actuating mechanism portion in a process of switching between the closed door retaining state and the door openable state; 
         FIG. 9  is a front view of the actuating mechanism portion in the door openable state; 
         FIG. 10  is a cross-sectional view taken on line X-X in  FIG. 3 ; 
         FIG. 11  is a plane view of a manual operation member and a ratchet driving plate; 
         FIG. 12  is a lateral cross-sectional view of the manual operation member and an operational hole attachment; 
         FIG. 13  is an exploded perspective view of the operational hole attachment viewed from its backside; 
         FIG. 14  is a plane view of a manual operation member and a ratchet driving plate according to a modified example of the first embodiment of the present invention; 
         FIG. 15  is a plane view of a manual gear member and a ratchet driving plate according to a second embodiment of the present invention; and 
         FIG. 16  is an exploded perspective view of an operational hole attachment according to a modified example of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention will be explained with reference to illustrations of drawing figures as follows. A first embodiment of the present invention will be explained referring to  FIGS. 1-14 . As shown in  FIG. 1 , a vehicle door  10  includes an outer panel  11  made from a pressed metal sheet. A door trim (lining)  19  is attached on an outer panel side portion wall  11 B serving as an interior surface of the outer panel  11 . An electric door latch apparatus  20  is mounted on the vehicle door  10  at an opposite side from a rotational center of the vehicle door  10 . The electric door latch apparatus  20  includes a main body unit  21  housed within the vehicle door  10  and an operational hole attachment  69  provided at the door trim (i.e., serving as the vehicle compartment side wall portion)  19 . The main body unit  21  has a cross section formed approximately in an L-shape when viewed from upward, and is fixed to the vehicle door  10  in a state where a corner portion of the main body unit  21  is fitted to a corner portion of the vehicle door  10  at an end of vehicle&#39;s interior side. 
     A striker  13  is provided on an inner surface of a doorframe  12  of the vehicle. The striker  13  is, for example, formed by bending a wire rod having a circular cross section into an approximately I-shape, and is arranged to project in an approximately horizontal direction. Further, the striker  13  is arranged so that leg portions thereof are positioned in parallel to each other in an open-close direction of the vehicle door  10  (i.e., right-left direction in  FIG. 1 ). One of the leg portions is engaged with the main body unit  21  of the electric door latch apparatus  20 . A cross-sectional view of a portion of the striker  13 , which is engaged with the main body unit  21 , is shown in  FIGS. 4-5 . A striker receiving portion which is configured to receive the striker  13  is formed as a cutout at a corner portion where a outer panel end portion wall  11 A serving as an end surface of the outer panel  11  of the vehicle door  10  and the outer panel side portion wall  11 B are positioned perpendicular to each other. 
     The main body unit  21  includes a striker engagement mechanism portion  29  provided at a portion facing the outer panel end portion wall  11 A of the vehicle door  10  and configured to engage with the striker  13 . The main body unit  21  further includes an actuating mechanism portion  39  provided at a portion facing the outer panel side portion wall  11 B of the vehicle door  10  and is configured to electrically actuate the striker engagement mechanism portion  29 . A housing  50  made of resin covers an approximately entire portion of the main body unit  21 . The resin-made housing  50 , as shown in  FIG. 1 , includes a mechanism cover portion  51  facing the outer panel end portion wall  11 A and a case main body portion  55  facing the outer panel side portion wall  11 B. A mechanism case  22  is fitted to the mechanism cover portion  51  and a side portion opening of the case main body portion  55  is covered by a cover body  57  (see  FIGS. 2-3 ). 
     The striker engagement mechanism portion  29  includes a latch  23  and a ratchet  24  (see  FIG. 4 ) housed in the mechanism case  22 . The mechanism case  22  is formed by assembling an approximately flat container shaped member  22 A made of resin to a metal sheet member  22 B. The metal sheet member  22 B is applied to the outer panel end portion wall  11 A of the vehicle door  10 . A rear portion, an upper portion, and a side portion of the mechanism case  22  are covered by the cover portion  51  ( FIG. 1 ) of the resin-made housing  50 . 
     As shown in  FIG. 2 , the mechanism case  22  includes bolt fixing portions  22 C (e.g., three portions in  FIG. 2 ). The main body unit  21  is fixed to the vehicle door  10  by applying the mechanism case  22  to an inner surface of the outer panel end portion wall  11 A and by screwing a bolt, which penetrates the outer panel end portion wall  11 A from outside, to the bolt fixing portion  22 C. Further, a striker groove  22 M is formed on the mechanism case  22  in accordance with the striker receiving portion formed on the outer panel  11  (see  FIGS. 2-3 ). In response to an opening or closing operation of the vehicle door  10 , the striker  13  ingresses to or egresses from the striker groove  22 M (see  FIGS. 4-5 ). 
     As shown in  FIG. 4 , the ratchet  24  of the striker engagement mechanism portion  29  is rotatably positioned at a lower level than the striker groove  22 M. The ratchet  24  integrally includes a ratchet support shaft  24 J and is rotatably supported relative to the metal sheet member  22 B and a sub-base  22 D of the mechanism case  22  by means of the ratchet support shaft  24 J. The ratchet  24  further includes a latch contact piece  24 A and a stopper contact piece  24 B which are arranged extending in directions being away from the ratchet support shaft  24 J. A torsion spring  25  (see  FIGS. 6-7 ) is provided between the ratchet  24  and the mechanism case  22 . The ratchet  24  is biased in a counterclockwise direction in  FIG. 4  by means of the torsion spring  25 . A positioning of the ratchet  24  is defined by the stopper contact piece  24 B contacting a ratchet stopper  26  which is made of rubber and provided at the mechanism case  22 . The position of the ratchet  24  in this state serves as a latch engagement position according to the embodiment of the present invention. 
     A latch support shaft  23 J of the striker engagement mechanism portion  29  is positioned at a higher level than the striker groove  22 M and the latch  23  is rotatably supported by means of the latch support shaft  23 J. The latch  23  is configured to soundproof by covering a metal plate with resin. The latch  23  includes a pair of engagement pawls  23 A,  23 B which are arranged approximately in parallel to each other. The void between the engagement pawls  23 A,  23 B serves as a striker receiving portion  23 G. A stopper contact portion  23 S is formed on the latch  23  to project therefrom at a portion opposite from an extending direction of the engagement pawl  23 A. In the event that the latch  23  rotates in a clockwise direction from a latched position shown in  FIG. 4 , the stopper contact portion  23 S comes in contact with a latch stopper  27  formed on the mechanism case  22  to position the latch  23  in an unlatched position shown in  FIG. 5 . 
     The latch  23  is biased towards an unlatched position side by means of a torsion spring  28  (see  FIG. 6 ) provided between the mechanism case  22  and the latch  23 . In a state where the vehicle door  10  is open, the latch  23  is positioned at the unlatched position shown in  FIG. 5 . In the unlatched position, one of the engagement pawls  23 A (hereinafter referred to as a front side engagement pawl  23 A) is retracted to the position higher than the striker groove  22 M and the other engagement pawl  23 B (hereinafter referred to as a rear side engagement pawl  23 B) is positioned on the striker groove  22 M, and an opening end of the striker receiving portion  23 G faces a striker entrance  22 S of the striker groove  22 M. 
     When closing the vehicle door  10  in the foregoing state, the striker  13  which enters, or ingresses the striker groove  22 M is received within the striker receiving portion  23 G, and the striker  13  pushes the rear side engagement pawl  23 B to rotate the latch  23  in the counterclockwise direction in  FIG. 5 . In those circumstances, the latch contact piece  24 A of the ratchet  24  is pushed by the front side engagement pawl  23 A and the rear side engagement pawl  23 B so that the ratchet  24  rotates against a biasing force of the torsion spring  25 . When closing the vehicle door  10 , as shown in  FIG. 4 , a portion of the striker groove  22 M closer to the striker entrance  22 S relative to the striker  13  is blocked by the front side engagement pawl  23 A so that the latch  23  and the striker  13  are engaged with each other. In the meantime, the latch contact piece  24 A of the ratchet  24  comes to engage a front side of the front side engagement pawl  23 A to restrict the rotation of the latch  23  towards the unlatched side (in the clockwise direction in  FIG. 4 ). Thus, the vehicle door  10  is retained at the closed state. This state is defined as a closed door retaining state. 
     In case of opening the vehicle door  10  in the foregoing state, the ratchet  24  is rotated to retract the latch contact piece  24 A from a contacting position with the front side engagement pawl  23 A. In order to rotate the ratchet  24 , an inside door lever  17  is provided at an interior side of the vehicle door  10  and an outside door lever  18  is provided at an outside of the vehicle door  10  as shown in  FIG. 10 . The door levers  17 ,  18  are connected to switches which are configured to turn on and off in response to the operation of the door levers  17 ,  18 , respectively. The switches and a motor  36  provided at the actuating mechanism portion  39  are electrically connected. 
     As shown in  FIG. 7 , the actuating mechanism portion  39  includes plural members including the motor  36  and is housed within the case main body portion  55  of the resin-made housing  50 . A connector portion  38  is provided on the case main body portion  55  at a top corner portion of an attachment wall  56  which faces the cover body  57 . The motor  36  is assembled within the case main body portion  55  at a lower level relative to the connector portion  38 . The connector portion  38  and the motor  36  are connected by a wire. 
     A worm wheel rotational shaft  30 J is provided on the attachment wall  56  to project towards the cover body  57  at a lower level relative to the motor  36 . A worm wheel  30  is rotatably supported on the worm wheel rotational shaft  30 J. The worm wheel  30  is geared with a worm gear  37  provided at an output rotation portion of the motor  36 . 
     A spur gear  31  is pivotally supported in a state being overlapped on the worm wheel  30  in a thickness direction. The spur gear  31  has a smaller diameter than that of the worm wheel  30  and is configured to always integrally rotate with the worm wheel  30 . 
     A driving plate rotational shaft (i.e., serving as a rotational shaft of the sector gear)  32 J is provided on the attachment wall  56  at a position between the worm wheel  30  and the mechanism case  22  in a manner projecting to be in parallel to the worm wheel rotational shaft  30 J. A ratchet driving plate  32  is rotatably supported on the driving plate rotational shaft  32 J. 
     The ratchet driving plate  32  includes a sector gear plate (i.e., serving as a the sector gear)  33  and a release lever  34 . The sector gear plate  33  and the release lever  34  are arranged to extend in opposite directions relative to the driving plate rotational shaft  32 J. The sector gear plate  33  includes a sector configuration having a rotation center of the ratchet driving plate  32  as a center. Further, the sector gear plate  33  is arranged to overlap a portion of the worm wheel  30  and a peripheral portion of the sector gear plate  33  is geared with the spur gear  31 . On the other hand, the release lever  34  is positioned at a lower level relative to a lift lever (i.e., serving as a rotational projection portion)  35  which is provided on a rear side of the mechanism case  22  and always integrally rotates with the ratchet  24 . 
     In the event that either the inside door lever  17  or the outside door lever  18  are operated in order to open the vehicle door  10 , the worm wheel  30  is rotated by an actuation of the motor  36  in the clockwise direction in  FIG. 7 , the ratchet driving plate  32  is rotated in the counterclockwise direction in  FIG. 7  in response to the clockwise rotation of the worm wheel  30 , and the release lever  34  lifts a lift lever (i.e., serving as a rotational projection portion)  35  from the bottom in an upward direction. In consequence, the ratchet  24  rotates in the clockwise direction in  FIG. 4  while slidably contacting the front side engagement pawl  23 A of the latch  23  so as to be retracted from a moving region of the latch  23  as shown in  FIG. 5 . That is, the ratchet  24  in this state serves as a latch engagement release position where the latch  23  is rotatable towards the unlatched position. Accordingly, a door openable state in which the vehicle door  10  is allowed to open is established. In the event that an opening operation for the vehicle door  10  is preformed (either pushing a door from a vehicle compartment side or pulling a door from the outside of the vehicle), the striker  13  moves towards the striker entrance  22 S of the striker groove  22 M and the latch  23  rotates towards the unlatched position (i.e., in the clockwise direction in  FIG. 4 ) by means of a biasing force of the torsion spring  28 . 
     A return spring  30 S (see  FIG. 6 ) biasing the worm wheel  30  in the counterclockwise direction in  FIG. 7  is provided between the worm wheel  30  and the attachment wall  56 . In a case where the motor  36  is not energized, the ratchet driving plate  32  is configured to return to an initial position shown in  FIG. 7  by means of the return spring  30 S. 
     More particularly, when the inside door lever  17  or the outside door lever  18  is in operation, the motor  36  is actuated to rotate the ratchet  24  towards the unlatched position, or latch disengagement position by the ratchet driving plate  32 . However, in those circumstances, in a case where the operation of the inside door lever  17  or the outside door lever  18  is stopped or in a case where a predetermined time elapses after a start of the operation of the inside door lever  17  or the outside door lever  18 , the motor  36  is de-energized so that the ratchet driving plate  32  returns to the initial position by the biasing force of the return spring  30 S. 
     The electric door latch apparatus  20  of the embodiment includes a manual rotation member (i.e., serving as a manual operation portion)  40  which allows to switch from the closed door retaining state to the door openable state by a manual operation at the inside of the vehicle compartment. The manual rotation member (i.e., serving as the manual operation portion)  40  is provided as a countermeasure for a case where the electric actuation is inoperable because of a trouble caused by/of the motor  36  or other electric systems in the closed door retaining state shown in  FIG. 4 . 
     According to this embodiment, the manual rotation member  40  is connected to the ratchet driving plate  32  among plural motor torque transmitting members (e.g., the worm wheel  30 , the spur gear  31 , the ratchet driving plate  32 ) for transmitting a torque of the motor  36  to the ratchet  24 . 
     As shown in  FIG. 7 , the manual rotation member  40  is positioned overlapping the sector gear plate  33  of the ratchet driving plate  32  in the plate thickness direction. The manual rotation member  40  is formed in a column configuration which is arranged in parallel to the worm wheel rotational shaft  30 J and the driving plate rotational shaft  32 J. As shown in  FIG. 12 , the manual rotation member  40  is positioned penetrating through a penetration hole  57 A formed on the cover body  57 . A base end portion of the manual rotation member  40  is rotatably fitted into the penetration hole  57 A. 
     A connection plate  41  is provided at a portion of the base end portion of the manual rotation member  40 . As shown in  FIG. 11 , the connection plate  41  extends in a radially outward direction of the manual rotation member  40  and has a half-circle like configuration. The connection plate  41  retains the manual rotation member  40  to the penetration hole  57 A. 
     A connection mechanism including a projection portion  33 A and a guide slot  41 A which engage with each other via a projection and a recess is formed on opposing surfaces of the manual rotation member  40  and the sector gear plate  33 . That is, the projection portion  33 A is formed on a surface of the sector gear plate  33  which faces the manual rotation member  40  and the guide slot  41 A is formed on a surface of the manual rotation member  40  facing the sector gear plate  33 . The projection portion  33 A and the guide slot  41 A are engaged with each other via the projection and the recess, thus forming a connection mechanism More particularly, the projection portion  33 A having a column shape projecting towards the manual rotation member  40  is provided on the sector gear plate  33  at a middle position thereof in a circumferential direction. The guide slot  41 A which extends in a radial direction and opens outward in the radial direction is formed on the connection plate  41  of the manual rotation member  40 . 
     As shown in  FIG. 11 , a rotational axis  40 J of the manual rotation member  40  is arranged to be in parallel to and to be offset from the driving plate rotational shaft  32 J. Further, as shown in  FIG. 8 , the rotational axis  40 J of the manual rotation member  40  is arranged to be positioned at a middle position on a line connecting the driving plate rotational shaft  32 J and the projection portion  33 A when the worm wheel rotational shaft  30 J, the driving plate rotational shaft  32 J and the projection portion  33 A are arranged in a straight line. 
     As shown in  FIG. 12 , the manual rotation member  40  includes a base end piece  42  which integrally includes the connection plate  41  and a top end piece  43  having a cylindrical structure. The base end piece  42  and the top end piece  43  are fixedly connected each other. An inner wall  43 A is provided at an axially middle portion of the top end piece  43 . A connection hole  43 C to which a top end portion of the base end piece  42  is fitted is formed at a portion of the manual rotation member  40  closer to the base end side relative to the inner wall  43 A. A tool fitting hole  43 B having a non-circular cross section is formed at a portion of the manual rotation member  40  closer to a top end side relative to the inner wall  43 A. As shown in  FIG. 7 , the tool fitting hole  43 B is configured to have, for example, a rectangular cross section to which a key plate (i.e., serving as a predetermined tool)  90  for starting a vehicle engine can be fitted. Edge portions of an opening rim of the tool fitting hole  43 B (i.e., edge portions formed by an inner surface of the tool fitting hole  43 B and a top end surface of the top end piece  43 ) are chamfered to have a tapered configuration. The top end piece  43  and the base end piece  42  are connected by means of a screw which penetrates the inner wall  43 A from the tool fitting hole  43 B side of the top end piece  43 . The manual rotation member  40  is formed accordingly. By structuring the connection hole  43 C of the top end piece  43  and the top end portion of the base end piece  42  to have the non-circular cross section, a relative rotation between the top end piece and the base end piece  42  can be securely restricted. 
     As shown in  FIG. 12 , a first operation hole (i.e., serving as an operation hole)  15  and a second operation hole  16  are formed penetrating through the door trim  19  and the outer panel side portion wall  11 B which form a side surface of an interior of the vehicle door  10 , respectively. The first operation hole  15  and the second operation hole  16  are formed at portions of the door trim  19  and the outer panel side portion wall  11 B facing the manual rotation member  40  (i.e., on an extension line of the rotational axis  40 J of the manual rotation member  40 ). The manual rotation member  40  penetrating through the cover body  57  and projecting from the resin-made housing  50  penetrates the second operation hole  16  which is formed on the outer panel side portion wall  11 B. A top end portion of the manual rotation member  40  is positioned in the void of the vehicle door  10  formed between the outer panel side portion wall  11 B and the door trim  19 . Namely, the top end portion of the manual rotation member  40  does not project from the door trim  19  and is positioned inside of the first operation hole  15  facing the first operation hole  15 . 
     The operational hole attachment  69  which serves as a portion of the electric door latch apparatus  20  is mounted on the first operation hole  15  formed on the door trim  19 . The operational hole attachment  69  includes a secure ring  60  which is fixed to a rim portion of the first operation hole  15  and a movable plate  63  rotatably assembled within the secure ring  60 . 
     The secure ring  60  includes a substantially cylindrical shape having an axial dimension smaller relative to a diameter. A top end portion of a ring main body  61  of the secure ring  60 , which is configured to be inserted into the first operation hole  15  has a flange configuration. Thus, the top end portion of the ring main body  61  is configured to be engaged with an opening rim of the first operation hole  15  facing the vehicle interior. The ring main body  61  includes a cylindrical inner surface and an engagement stepped portion  61 A at which an inner diameter is expanded stepwise is formed at an opening rim of the top end portion. The secure ring  60  is fixed by sandwiching the door trim  19  (circumferential rim portion of the first operation hole  15 ) between the secure ring  60  and a retaining ring  62  which is retained to the ring main body  16  by means of screws from a backside of the door trim  19  in a plate thickness direction in a state where the ring main body  61  is inserted in the first operation hole  15 . The first operation hole  15  and a portion fitting into the first operation hole  15  of the ring main body  61  is configured to have a non-circular cross section so that the secure ring  60  does not rotate relative to the first operation hole  15 . 
     The movable plate  63  is formed in a column shape having an axial dimension smaller relative to a diameter. A flange  64 A of the movable plate  63  is integrally formed on a top end portion of a plate main body  64  which is fitted into the secure ring  60 . The flange  64 A is engaged with the engagement stepped portion  61 A of the secure ring  60 . Further, as shown in  FIG. 13 , a flange plate  65  is secured to a base end portion of the plate main body  64  by means of screws so that the movable plate  63  is retained to the secure ring  60 . The movable plate  63  is retained to the secure ring  60  by the flange  64 A of the plate main body  64  and the flange plate  65 . 
     A key insertion hole  63 A is formed penetrating through the movable plate  63 . The key insertion hole  63 A penetrates through the movable plate  63  (plate main body  64  and the flange plate  65 ) in an axial direction and includes a rectangular cross section to which the key plate  90  for starting the vehicle engine can be inserted. The configuration of the key insertion hole  63 A and cross-sectional configuration of the tool fitting hole  43 B formed on the manual rotation member  40  is approximately the same. The key insertion hole  63 A and the tool fitting hole  43 B coincide with each other in an aligning direction of the movable plate  63  and the manual rotation member  40  as shown in  FIG. 3 . The electric door latch apparatus  20  is structured accordingly. 
     Next, an operation for switching door states from the closed door retaining state to the door openable state by manually operating the manual rotation member  40  in the event that the electric door latch apparatus  20  becomes electrically inoperable in the closed door retaining state (i.e., shown in  FIG. 4 ) will be explained hereinafter. 
     In order to rotate the manual rotation member  40 , first, the key plate  90  is inserted into the first operation hole  15  of the door trim  19  and is fitted to the tool fitting hole  43 B of the manual rotation member  40  provided at the inner side of the door trim  19  (shown in  FIG. 10 ). When rotating the key plate  90  in the counterclockwise direction viewed from the vehicle interior side in the state where the key plate  90  is fitted to the tool fitting hole  43 B shown in  FIG. 10 , the manual rotation member  40  rotates in the same direction to the rotating direction of the key plate  90 , and the ratchet driving plate  32  connected to the manual rotation member by means of the connection mechanism (projection portion  33 A and the guide slot  41 A) rotates in the counterclockwise direction in  FIG. 7 . Accordingly, the release lever  34  of the ratchet driving plate  32  comes in contact with a bottom surface of the lift lever  35  to lift the lift lever  35  in the upward direction. 
     In response to the movement of the lift lever  35  in the upward direction, the ratchet  24  rotates integrally with the lift lever  35  in the clockwise direction in  FIG. 4  while slidably contacting the front side engagement pawl  23 A of the latch  23  to be retracted from the moving range of the latch  23 . Accordingly, the latch  23  becomes rotatable to the unlatched position side and the door state is switched to the door openable state. In the door openable state, the vehicle door  10  can be opened if the vehicle door  10  is pushed from the vehicle compartment side. That is, even when the electric door latch apparatus  20  becomes electrically inoperable in the closed door retaining state, the door state is manually switched to the door openable state, and thus, occupants are able to egress from the vehicle. 
     In the event that the rotation of the motor  36  deteriorates in the door openable state of the electric door latch apparatus  20  (shown in  FIG. 9 ) or that the return spring does not work, the door state may not be switched to the closed door retaining state. Because of this drawback, even if the vehicle is operable, it cannot be actually operated. With the construction of the electric door latch apparatus  20  according to the embodiment, because the manual rotation member  40  is connected to one of the plural motor torque transmitting members for transmitting the torque of the motor  36  to the ratchet  24 , that is, the ratchet driving plate  32 , in the event that the electric door latch apparatus  20  becomes electrically inoperable in the door openable state, for example, shown in  FIG. 9 , the door state can be manually switched to the closed door retaining state. 
     Particularly, first, the key plate  90  is inserted into the first operation hole  15  and is fitted to the tool fitting hole  43 B of the manual rotation member  40  positioned at the inner side relative to the first operation hole  15 . By rotating the key plate  90  in the clockwise direction viewed from the vehicle interior side in this state, the manual rotation member  40  is rotated in the same direction to the rotating direction of the key plate  90  to rotate the ratchet driving plate  32  in the clockwise direction in  FIG. 9 . Accordingly, the release lever  34  of the ratchet driving plate  32  moves in a direction being away from the lift lever  35  (i.e., in the downward direction). 
     In response to the movement of the release lever  34  being away from the lift lever  35 , the ratchet  24  rotates towards the latched position, or the latch engagement position by means of the biasing force of the torsion spring  25  to enter the moving range of the latch  23 . In a case where the vehicle door  10  is closed in this state, as shown in  FIG. 4 , the ratchet  24  comes in contact with the front side of the front side engagement pawl  23 A of the latch  23 . Accordingly, the latch  23  is restricted from being rotated towards the unlatched position (i.e., in the clockwise direction in  FIG. 4 ) and the vehicle door  10  is maintained at the closed state. 
     As explained above, according to the electric door latch apparatus  20  of the embodiment, the manual rotation member  40  cannot be rotated unless the key plate  90  is inserted via the first operation hole  15  to be fitted to the tool fitting hole  43 B. Thus, when the electric door latch apparatus  20  is normally operated, inappropriate changes to the door openable state can be securely prevented by removing the key plate  90  from the tool fitting hole  43 B. Further, because the key plate  90  for rotating the manual rotation member  40  is provided on the door trim  19  which is located at a position where a passenger&#39;s hand can relatively readily reach and which is readily visible, the visibility of the manual rotation member  40  can be enhanced compared to the known electric door latch apparatuses. 
     Further, because the manual rotation member  40  is arranged overlapping the sector gear plate  33  formed on the ratchet driving plate  32  in the plate thickness direction, a dimension of the electric door latch apparatus  20  in a direction being orthogonal to the rotational shaft of the ratchet driving plate  32  is downsized compared to a case where the manual rotation member  40  is arranged on a lateral side of the ratchet driving plate  32 . 
     Further, in a case where the manual rotation member  40  is connected to one of the plural motor torque transmitting members, the motor  36  may become an operational resistance when rotating the manual rotation member  40 . In response to this drawback, according to the embodiment of the present invention, the rotational axis  40 J of the manual rotation member  40  is offset from the driving plate rotational shaft  32 J and is positioned closer to the projection portion  33 A in a radial direction of the sector gear plate  33  than the driving plate rotational shaft  32 J to the projection portion  33 A in the radial direction of the sector gear plate  33 . In other words, a distance between the rotational axis  40 J and the projection portion  33 A is shorter than a distance between the projection portion  33 A and the driving plate rotational shaft  32 J in a radial direction of the sector gear plate  33 . Accordingly, with the construction of the embodiment, the operational resistance is reduced compare to a construction in which the rotational axis  40 J of the manual rotation member  40  is arranged coaxially to the driving plate rotational shaft  32 J. 
     Further, according to the embodiment, because the manual rotation member  40  is rotated by means of the key plate  90  corresponding to a key plate for starting the engine, it is not necessary for an operator to carry another tool for rotating the manual rotation member  40  with him/her. In addition, this prevents the operator from leaving the tool for rotating the manual rotation member  40  behind somewhere outside the vehicle when using a vehicle. 
     In those circumstances, because the tool which can contact the manual rotation member  40  arranged within the vehicle door  10  is limited to members which can pass through the rectangular key insertion hole  63 A formed on the movable plate  63 , for example, the key plate  90  for starting the engine. Thus, the manual rotation member  40  is further securely prevented from being operated with an inappropriate tool. 
     In a case where the operation lever for manually operating the electric door latch apparatus is positioned away from a vehicle door or a door frame (e.g., under a seat or an instrument panel), a wire is required for connecting the operation lever and the electric door latch apparatus. In those circumstances, this may cause drawbacks such as a decline of workability when assembling the electric door latch apparatus (e.g., handling of the wire) or an increase of the weight due to the wire. However, according to the construction of the embodiment of the present invention, because the key plate  90  and the electric door latch apparatus  20  is directly connected, the aforementioned drawbacks do not happen. 
     A modified example of the first embodiment is explained hereinbelow. According to the modified example, instead of the projection portion  33 A formed on the sector gear plate  33  and the guide slot  41 A formed on the manual rotation member  40 , a projection portion  40 A is formed on the manual rotation member  40  and a guide slot  33 B is formed on the sector gear plate  33 . More particularly, as shown in  FIG. 14 , the projection portion  40 A projecting towards the sector gear plate  33  is provided on a tip end of a connection plate  44  formed approximately in a triangular shape which extends outwardly in a radial direction of the manual rotation member  40 . The projection portion  40 A is arranged being offset from the rotational axis  40 J of the manual rotation member  40 , the guide slot  33 B is formed on a middle portion in a circumferential direction of the sector gear plate  33  and has a long hole shape extending in the radial direction of the sector gear plate  33 , and the guide slot  33 B and the projection portion  40 A are engaged via a recess and a projection. According to the construction of the modified example, advantages and effects similar to the first embodiment are attained. 
     A second embodiment of the present invention will be explained as follows. As shown in  FIG. 15 , a connection structure between the manual operation portion and the ratchet driving plate according to the second embodiment of the electric door latch apparatus differs from that of the first embodiment. Because other constructions are common to the first embodiment, the same numeral is provided for the same structure and explanations for the common constructions are not repeated. 
     A manual gear member  80  serving as a manual operation portion includes a construction in which the connection plate  41  of the manual rotation member  40  is replaced by a sector gear plate  81 . The sector gear plate  81  extends outwardly in a radial direction of the manual gear member  80 , includes approximately half a circle shape, and includes an outer gear  81 G at an outer periphery thereof. The manual gear member  80  is arranged overlapping the sector gear plate  33  of the ratchet driving plate  32 . A rotational axis  80 J of the manual gear member  80  is arranged in parallel to and offset from the driving plate rotational shaft  32 J, and is positioned closer to the worm wheel rotational shaft  30 J than the driving plate rotational shaft  32 J to the worm wheel rotational shaft  30 J. 
     An arc shaped stepped portion  33 C is formed on the sector gear plate  33  provided at the ratchet driving plate  32  at a position facing the manual gear member  80  (more particularly, sector gear plate  81 ). A radially outer portion of the arc shaped stepped portion  33 C projects stepwise towards the manual gear member  80 . The arc shaped stepped portion  33 C includes an arc-like shape having the driving plate rotational shaft  32 J as a center. The arc shaped stepped portion  33 C is positioned closer to an arc shaped outer periphery of the sector gear plate  33 . An arc shaped inner gear  33 G is formed on a surface of a step of the arc shaped stepped portion  33 C which faces the driving plate rotational shaft  32 J. The outer gear  81  G of the sector gear plate  81  provided at the manual gear member  80  is engaged with the inner gear  33 G. Accordingly, in response to the rotational operation of the manual gear member  80 , the ratchet driving plate  32  rotates in the same direction. With the construction of the second embodiment of the electric door latch apparatus, the advantages and effects similar to the first embodiment can be attained. 
     Other modified examples will be explained hereinafter. According to the foregoing embodiments, the electric door latch apparatus  20  is structured by the main body unit  21  built in the vehicle door  10  and the operational hole attachment  69  mounted on the door trim  19 . However, only the main body unit  21  may construct the electric door latch apparatus  20 . 
     According to the foregoing embodiments, the manual operation portion (the manual rotation member  40 , manual gear member  80 ) is connected to the ratchet driving plate  32 . However, the manual operation portion (the manual rotation member  40 , manual gear member  80 ) may be connected to the worm wheel  30  or connected to the worm wheel  30  via the spur gear  31 . 
     According to the foregoing embodiments, the manual operation portion (the manual rotation member  40 , the manual gear member  80 ) is provided separately from the movable plate  63  of the operational hole attachment  69 . However, the construction is not limited, and the manual operation portion (the manual rotation member  40 , the manual gear member  80 ) and the movable plate  63  of the operational hole attachment  69  may be integrally formed or may be connected so as to integrally rotate. 
     According to the foregoing embodiments, the manual operation portion (the manual rotation member  40 , the manual gear member  80 ) is connected to the one of the plural motor torque transmitting members (the ratchet driving plate  32 ). However, the manual operation (the manual rotation member  40 , the manual gear member  80 ) may be independently provided without connecting to any of the motor torque transmitting members (the worm wheel  30 , the spur gear  31 , the ratchet driving plate  32 ) and the lift lever  35  may be directly pushed by the rotation operation of the manual operation portion (the manual rotation member  40 , the manual gear member  80 ). According to this construction, because the operational resistance of the motor  36  is not applied when operating the manual operation portion (the manual rotation member  40 , the manual gear member  80 ), the rotational operation of the manual operation portion can be performed with less force. 
     According to the foregoing embodiments, the tool fitting hole  43 B is configured to fit with the key plate  90  for starting the vehicle engine. However, the tool fitting hole  43 B may also be configured to fit with another key plate (e.g., a key for a residential door, a key for motor cycle). Further, the tool fitting hole  43 B may be configured to fit with a tool for exclusive use which has a particular cross-sectional configuration which is different from the cross section of the key plate  90  for starting the engine. 
     Although not mentioned in the foregoing embodiments, a shutter for closing the key insertion hole  63 A of the movable plate  63  may be provided in a normal state. Alternatively, a keyhole cap may be detachably provided at the key insertion hole  63 A in the normal state. 
     Although the rotational shaft of the manual operation portion (the manual rotation member  40 , the manual gear member  80 ) is offset from the rotational shaft of the ratchet driving plate  32  according to the foregoing embodiments, the rotational shaft of the manual operation portion (the manual rotation member  40 , the manual gear member  80 ) may be arranged coaxially to the rotational shaft of the ratchet driving plate  32 . 
     The ratchet  24  and the lift lever  35  may be either integrally formed as a single unit or formed as separate parts. Further, according to the foregoing embodiments, the ratchet driving plate  32  is configured to push the lift lever  35 . However, alternatively, the ratchet driving plate  32  may be configured to directly push the ratchet  24 . 
     The electric door latch apparatus  20  may be provided at a hinge type door, or a hinged door. Alternatively, the electric door latch apparatus  20  may be provided at a slide type door, or a sliding door. 
     In order to prevent the movable plate  63  from unintentionally rotating relative to the secure ring  60  because of vibrations, or the like, the following construction may be provided. For example, as shown in  FIG. 16 , notches (recesses)  16 B may be formed on a rear end portion of the ring main body  61  and a projection portion  65 A which is flexible and is configured to engage with the notches  16 B via a recess and a projection are formed on the flange plate  65  of the movable plate  63 . According to this construction, in the event that the movable plate  63  rotates relative to the secure ring  60 , the projection portion  65 A may come out of the notch  16 B. Accordingly, unless performing a rotational operation with the tool, the movable plate  63  does not rotate, and thus the a displacement between the key insertion hole  63  and the tool fitting hole  43 B due to the vibrations, or the like, is prevented. Further, with this construction, when performing the rotational operation with the inserted tool, the operator can sense a clicking operational feeling. 
     According to the embodiment, in order to switch the door state to the door openable state in a condition where the electric door latch apparatus  20  is electrically inoperable, the key plate  90  (the predetermined tool) is inserted into the first operation hole  15  (the operation hole) formed on the door trim  19  (the vehicle compartment side wall portion) and is rotated in a state where the key plate  90  (the predetermined tool) is fitted to the tool fitting hole  43 B of the manual rotation member  40  or the manual gear member  80  (the manual operation portion). In response to the rotation of the key plate  90  (the predetermined tool), the manual rotation member  40  or the manual gear member  80  (the manual operation portion) integrally rotates with the key plate  90  (the predetermined tool) to switch the door state from the closed door retaining state to the door openable state. 
     As explained above, according to the construction of the embodiment (of the present invention), it is impossible to operate the manual rotation member  40  or the manual gear member  80  (the manual operation portion) to rotate unless the key plate  90  (the predetermined tool) is inserted through the first operation hole  15  (the operation hole) and fitted to the tool fitting hole  43 B. Thus, by removing the key plate  90  (the predetermined tool) from the tool fitting hole  43 B in the normal state where the electric door latch apparatus  20  is electrically operable, switching operation to the door openable state by an inappropriate operation, for example, by a child&#39;s mischief can be securely prevented. Further, because the key plate  90  (the predetermined tool) for operating the manual rotation member  40  or the manual gear member  80  (the manual operation portion) is mounted on the door trim  19  (the vehicle compartment side wall portion) which is relatively readily reachable and readily visible, the operability of the manual rotation member  40  or the manual gear member  80  (the manual operation portion) is enhanced compared to the known structure in which the operation lever is positioned under the seat. 
     According to the embodiment of the present invention, the electric door latch apparatus  20  includes the latch  23  rotating for engaging with the striker  13  provided on the vehicle body, the ratchet  24  rotating between the latched position in which the latch  23  is prohibited from rotating in a direction which disengages the striker  13  therefrom and the unlatched position in which the latch  23  is allowed to rotate in a direction which disengages the striker  13  therefrom, the ratchet  24  being biased towards the latched position, the motor  36  performing the electric actuation, and the plural motor torque transmitting members  30 ,  31 ,  32  for transmitting a torque of the motor  36  to the ratchet  24 . The closed door retaining state is established by positioning the ratchet  24  at the latched position when the vehicle door  10  is at the closed position and the door openable state is established by rotating the ratchet  24  to the unlatched position. 
     According to the embodiment of the present invention, the electric door latch apparatus  20  further includes the ratchet driving plate  32  rotatably provided as one of the motor torque transmitting members, the ratchet driving plate  32  pushes the lift lever  35  provided at the ratchet  24  in one direction to rotate thereof for rotating the ratchet  24  from the latched position to the unlatched position. The manual rotation member  40  or the manual gear member  80  is connected to or integrally formed with one of the plurality of motor torque transmitting members  30 ,  31 , and  32 . 
     According to the embodiment, because the manual rotation member  40  or the manual gear member (the manual operation portion)  80  is connected to or integrally formed with the ratchet driving plate  32  or the worm wheel  30  or the worm wheel  30  via the spur gear  31  corresponding to one of the plural motor torque transmitting members, the ratchet driving plate  32  can be rotated not only in a direction to push the lift lever (rotational projection portion)  35  but also in a reverse direction (i.e., in a direction being away from the lift lever  35 ) by the rotational operation of the manual rotation member  40  or the manual gear member (the manual operation portion)  80 . 
     For example, in a case where the manual operation portion is provided separately from the plural motor torque transmitting members and the manual operation portion and the ratchet driving plate are configured to individually push the lift lever (rotational projection portion) of the ratchet, the following drawbacks are caused. That is, in the event that the ratchet assumes not be able to return to the latched position in a condition where the ratchet driving plate pushes the lift lever of the ratchet from one direction (i.e., the ratchet is in the unlatched position, the door openable state), the ratchet cannot be returned to the latched position by operating the manual rotation member or the manual gear member (the manual operation portion) and the door state may not be able to be switched to the closed door retaining state. 
     On the other hand, according to the construction of the embodiment, even when the ratchet  24  is not returnable to the latched position in a state where the ratchet  24  is in the unlatched position, the ratchet driving plate  32  can be rotated in a direction to separate the ratchet driving plate  32  from the lift lever (rotational projection portion)  35  (i.e., in a reverse direction from the pushing direction) by the rotational operation of the manual rotation member  40  or the manual gear member (the manual operation portion)  80 . Accordingly, the ratchet can be securely returned to the latched position. Namely, the door state is securely switched to the closed door retaining state. 
     According to the embodiment of the electric door latch apparatus  20 , the ratchet driving plate  32  includes the sector gear plate  33  engaged with another of the motor torque transmitting members  30 ,  31 , the manual operation portion is arranged overlapping the sector gear plate  33  in a thickness direction thereof and includes the manual rotation member  40  which is rotatable about the rotational axis  40 J being in parallel to and being offset from the rotational shaft ( 32 J) of the sector gear ( 33 ). 
     According to the embodiment of the present invention, the electric door latch apparatus further includes the connection mechanism including the projection portion  33 A,  40 A and the guide slot  41 A,  33 B, which engages with each other via a projection and a recess. The connection mechanism is formed on opposing surfaces of the manual rotation member  40  and the ratchet driving plate  32 . The guide slot  41 A,  33 B is formed on the opposing surface of one of the manual rotation member  40  and the ratchet driving plate  32  and arranged in a radial direction thereof. The projection portion  33 A,  40 A is formed on the opposing surface of the other of the manual rotation member  40  and the ratchet driving plate  32  and positioned being away from a rotational center thereof. The manual rotation member  40  and the sector gear plate  33  are rotated in cooperation with each other via the connection mechanism. 
     According to the embodiments, by rotating the manual rotation member  40  serving as the manual operation portion, the sector gear plate (the sector gear)  33  connected to the manual rotation member  40  via the connection mechanism rotates in response to the rotational operation of the manual rotation member  40  so that the ratchet driving plate  32  having the sector gear plate  33  is rotated. In consequence, the ratchet driving plate  32  pushes the lift lever (rotational projection portion)  35  of the ratchet  24  from one direction to rotate the ratchet  24  from the latched position to the unlatched position. In those circumstances, the rotational axis  40 J of the manual rotation member  40  is arranged in parallel with and offset from the driving plate rotational shaft (the rotational shaft of the sector gear)  32 J. Because the manual rotation member  40  and the sector gear plate  33  which respectively rotate about the rotational axes arranged being in parallel each other and being offset from each other are rotated in cooperation with each other, the guide slot  33 B, or the guide slot  41 A of the connection mechanism is configured to extend in a radial direction of the member having the guide slot  33 B, or the guide slot  41 A. Accordingly, when rotating the manual rotation member  40 , the projection portion  33 A or the projection portion  40 A becomes movable in the guide slot  33 B, or the guide slot  41 A, thus allowing the manual rotation member  40  to rotate in association with the sector gear plate  33  (ratchet driving plate  32 ). 
     According to the embodiments, a dimension of the electric door latch apparatus  20  in a direction being orthogonal to the rotational shaft  32 J of the ratchet driving plate  32  is downsized compared to a case where the manual rotation member  40  is arranged on a lateral side of the ratchet driving plate  32 . 
     According to the embodiment of the electric door latch apparatus  20 , the ratchet driving plate  32  includes a sector gear  33  engaged with another of the motor torque transmitting members  30 ,  31 , and an arc shaped stepped portion  33 C formed on the sector gear  33  at a position closer to an arc shaped outer periphery portion, and an arc shaped inner gear  33 G formed on the arc shaped stepped portion  33 C. 
     According to the embodiment of the electric door latch apparatus  20 , the manual operation portion is arranged overlapping the sector gear  33  in a thickness direction thereof, is rotatable about the rotational axis  80 J being in parallel to and being offset from the rotational shaft  32 J of the sector gear  33 , and includes the manual gear member  80  having the outer gear  81 G configured to engage with the arc shaped inner gear  33 G. 
     According to the embodiments, when rotating the manual gear member  80  serving as the manual operation portion, the sector gear plate (the sector gear)  33  having the arc shaped inner gear  33 G engaged with the outer gear  81 G of the manual gear member  80  is rotated, and the ratchet driving plate  32  having the sector gear plate  33  is rotated. In consequence, the ratchet driving plate  32  pushes the lift lever (rotational projection portion)  35  of the ratchet  24  to rotate the ratchet  24  from the latched position to the unlatched position. 
     In those circumstances, because the manual gear member  80  is arranged overlapping the sector gear plate  33  formed on the ratchet driving plate  32  in the plate thickness direction, a dimension of the electric door latch apparatus  20  in a direction being orthogonal to the rotational shaft  32 J of the ratchet driving plate  32  is downsized compared to a case where the manual gear member  80  is arranged on a lateral side of the ratchet driving plate  32 . 
     According to the embodiment of the electric door latch apparatus, the manual operation portion  40 ,  80  is configured to be rotated by inserting therein the key plate (vehicle key)  90  as the predetermined tool. 
     According to the embodiments, because the manual rotation member  40  or the manual gear member  80  can be rotated by means of the vehicle key, operators can be free from the burden that he/she has to carry another tool for rotating the manual rotation member  40  or the manual gear member  80  separately from the vehicle key. 
     According to the embodiment of the present invention, the electric door latch apparatus  20  further includes the  60  secure ring being secured to a rim portion of the first operation hole (operation hole)  15  of the vehicle door  10 , and the movable plate  63  rotatably assembled to an inside of the secure ring  60 . The movable plate includes a rectangular key insertion hole  63 A to which the key plate (vehicle key)  90  is insertable. 
     According to the embodiments, the tool which can contact the manual rotation member  40  or the manual gear member (manual operation portion)  80  is limited to the one having a configuration which can be inserted through the key insertion hole  63 A formed in a rectangular shape such as a vehicle key, unwanted operation of the manual rotation member  40  or the manual gear member  80  by an inappropriate tool can be more securely prevented. 
     The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the sprit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.