Abstract:
An anti-panic mechanism for a vehicle door latch device comprises a movable member provided between to an open link and a lock lever, and an anti-panic spring elastically connecting the lock lever with the movable member. When an unlocking operation by an inside lock button is not completed normally due to a first opening operation of an open handle, the movable member is displaced by a spring force of the anti-panic spring to move the open link to an engageable position after the open lever is returned to an initial position. The movable member and lock lever are coaxially pivoted by a single common shaft.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an anti-panic mechanism of vehicle door latch device. 
     2. Description of Related Art 
     In the conventional typical vehicle door latch device, the unlocking operation performed by using the inside lock button or the centralized door lock system or so forth is not completed normally, if the door open handle is subjected to the door opening operation, and the door cannot be opened. This state is often called a “panic state”. In order to open the panicked door, it is necessary to return the open handle to a stand-by position (initial position) and to unlock the latch device with the lock button or the like again before the next opening operation of the door open handle is made to perform. Thus, when the door (latch device) falls into the panic state, the secondary unlocking operation and the secondary door opening operation are required. 
     The door latch device provided with the anti-panic mechanism reducing the complicated operation caused by the panic state is known (Japanese Utility Model Application Laid-Open No. SHO 58-101949, Japanese Patent Application Laid-Open No. HEI 11-324451). The prior art anti-panic mechanism is to exclude the second unlocking operation. Even if when the first unlocking operation is not completed normally due to the panic state caused by the early or simultaneously performed door opening operation, the anti-panic mechanism displaces the door latch device into unlocked state automatically after the open handle is returned to the stand-by position. Consequently, it is possible to open the door by the second door opening operation without the second unlocking operation. 
     The prior anti-panic mechanism is provided with a movable member urged by an anti-panic spring, and the movable member is pivotally mounted on the door latch device with a dedicated shaft, so that many parts are used. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide improved anti-panic mechanism which has a movable member pivotally mounted on a lock shaft which supports a lock lever rotatably. It is possible to decrease the number of parts of the device in such a way as to mount the movable member on the lock shaft. In addition, such a combination between the lock lever mounted on the lock shaft and the movable member has a size that is capable of being formed to be the approximately same size as the conventional lock lever. For that reason, it is possible to prevent an increase in size of the door latch device to the utmost. In addition, the movable member mounted on the lock shaft is turned together with the lock lever. For this means, it is easy for the movable member to obtain space where the movable member turns. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a door latch assembly of the present invention; 
         FIG. 2  is a rear elevation showing members provided at rear surface side of the door latch assembly; 
         FIG. 3  is a cross-sectional view showing a contact surface of an open link and a passageway of the latch assembly; 
         FIG. 4  is an arranging view of respective members in the locked state; 
         FIG. 5  is an arranging view showing a state in which the open lever is rotated in a door opening direction in the locked state; and 
         FIG. 6  is an arranging view showing a state in which the lock lever is displaced into unlocked position at the state of  FIG. 5 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows the front of the door latch device according to the present invention. The door latch device has a latch assembly  10  mounted on a vehicle door (not shown) and a striker  11  fixed on the vehicle body (not shown). The latch assembly  10  has a latch  12  which is engaged with the striker  11  when the door is closed, and a ratchet  13  for maintaining engagement between the latch  12  and the striker  11 . The latch  12  is rotatably contained within a recess  15  formed on the surface of a latch body  14  by means of a latch shaft  16  in a back-and-forth direction of the latch device, and the ratchet  13  is rotatably contained within the recess  15  by means of a ratchet shaft  17  in the back-and-forth direction. 
     The latch  12  is, in  FIG. 1 , urged in the clockwise direction by elasticity of a latch spring  18 , and the ratchet  13  is urged in the counterclockwise direction by elasticity of a ratchet spring  19 . The latch  12  as shown in  FIG. 1  is located in unlatched position (door open position) by the elasticity of the latch spring  18 . When the door is moved toward a door-closed position, the striker  11  comes into contact with a U-shaped groove  20  of the latch  12  to rotate the latch  12  counterclockwise. When the latch  12  is rotated up to a half-latched position, the ratchet  13  is engaged with a first step  21  of the latch  12  and the door reaches a half-closed position, and when the latch  12  comes to a full-latched position, the ratchet  13  is engaged with a second step  22  of the latch  12  and the door is maintained at a full-closed position. 
     The ratchet  13  has a ratchet pin  24  projecting to the rear side of the latch body  14  through an opening  23  of the latch body  14 . To the front surface of the latch body  14 , a metal cover plate  25  for covering the recess  15  is fixed. The cover plate  25  is shown partially in  FIG. 1 . 
     A metal back plate  26  shown in  FIG. 2  is fixed on a rear surface of the latch body  14 . The back plate  26  is provided with a parallel plate  26 A in approximately parallel with the cover plate  25 . The latch body  14  is sandwiched between the cover plate  25  and the parallel plate  26 A. The back plate  26  has a bent plate  26 B which is angled to extend backward from the interior side edge of the parallel plate  26 A. 
     The latch assembly  10  has an open lever  27  for releasing the ratchet  13  from the latch  12  so as to open the door. The open lever  27  is pivotally mounted on the parallel plate  26 A (latch body  14 ) by using the latch shaft  16  or by using another shaft. The open lever  27  is operatively coupled to an outside open handle  28  and an inside open handle  29  of the door, so that the open lever  27  is rotated counterclockwise in response to the door opening operation of the handles  28  and  29  to be displaced from the stand-by position ( FIGS. 2 and 4 ) to an actuated position ( FIGS. 5 and 6 ). 
     The latch assembly  10  further has a lock lever  30  which is pivotally mounted on the parallel plate  26 A (latch body  14 ) by using a lock shaft  31 . It is noted that the ratchet shaft  17  can be served as the lock shaft  31 . The lock lever  30  is arranged between the parallel plate  26 A and the latch body  14 . The lock lever  30  is operatively coupled to an inside lock button  32  (and a door key cylinder  33 , if necessary), and the lock lever  30  is held at one of a locked position L or an unlocked position U by an over center spring  34 . 
     A movable member  35  for panic state measures is pivotally mounted on the lock shaft  31 . A main body of the movable member  35  is arranged at rear side of the parallel plate  26 A. An anti-panic spring  36  is arranged between the movable member  35  and the lock lever  30 . A coil portion  36 A of the spring  36  is arranged around the lock shaft  31 . One leg part  36 B of the spring  36  is brought into contact with a projecting part  37  of the lock lever  30  which is projected to rearward beyond the parallel plate  26 A. The other leg part  36 C of the spring  36  is brought into contact with a projecting part  38  of the movable member  35 . The movable member  35  is urged in the unlocking (counterclockwise) direction due to spring force of the spring  36 , and is maintained in the state where the member  35  comes into contact with the projecting part  37  of the lock lever  30 . Generally, the movable member  35  is rotated integrally with the lock lever  30 . 
     The movable member  35  is provided integrally with a forwardly projecting pin part  39  which is slidably engaged with a rearward guide slot  41  of an open link  40 . An upper part of the open link  40  is pivotally coupled to the open lever  27 . When the movable member  35  is displaced to the unlocked position ( FIGS. 2 and 3 ) together with the lock lever  30 , the open link  40  shifts to left side engageable position, and when the movable member  35  is displaced to the locked position ( FIGS. 4 and 5 ) together with the lock lever  30 , the open link  40  shifts to right side non-engageable position. 
     A contact portion  42  is provided at the front surface of the open link  40 . The contact portion  42 , when the open link  40  is placed at the engageable position ( FIGS. 2 and 3 ), is arranged in facing relationship with the ratchet pin  24  and engageable with the ratchet pin  24  in the up-and-down direction. Thus, when the open link  40  moves downward due to rotation of the open lever  27 , the contact portion  42  comes into contact with the ratchet pin  24  and moves it downward, thereby the ratchet  13  is released from the latch  12  and the door is opened. When the open link  40  is displaced to the non-engageable position ( FIG. 4 ), the contact portion  42  is alienated from the ratchet pin  24 , thereby the downward movement of the open link  40  cannot open the door as shown in  FIG. 5 . 
     A passageway  43  for the ratchet pin  24  is formed at front side of the open link  40 . When the open link  40  moves downward while the open link  40  is located at the non-engageable position, the ratchet pin  24  relatively moves upward within the passageway  43 . A right side wall  44  of the passageway  43  functions as an anti-unlock wall. The wall  44  restricts the movement of the open link  40  (lock lever  30 ) toward the engageable position (unlocked position) by the engagement with the ratchet pin  24  when the ratchet pin  24  is situated within the passageway  43 . 
     OPERATION 
     In the unlocked state of  FIGS. 2 and 3 , when the locking operation of the inside lock button  32  or the like is performed, the lock lever  30  is rotated clockwise to move to the locked position L exceeding the dead point of the over center spring  34 , and the movable member  35  also moves to the locked position, the open link  40  then moves rightward to be displaced to the non-engageable position, thereby the latch device becomes the locked state as shown  FIG. 4 . 
     In the locked state of  FIG. 4 , when performing the door opening operation of the outside or inside open handles  28 ,  29 , the open lever  27  is rotated counterclockwise as shown in  FIG. 5 , and the open link  40  moves downward. However, in the locked state, the contact portion  42  of the open link  40  cannot come into contact with the ratchet pin  24 , therefore, the ratchet pin  24  does not move downward, consequently the door is not opened. 
     In the state of  FIG. 5  where the open lever  27  is in the actuated position by the door opening operation of the outer side open handle  28  or the inner side open handle  29 , when unlocking operation of the inside lock button  32  and so forth is performed, the lock lever  30  is displaced to the unlocked position U independently as shown in  FIG. 6  while leaving the movable member  35  at the locked position. 
     Namely, as shown in  FIG. 5 , when the open link  40  moves downward in the non-engageable state, the ratchet pin  24  relatively enters into the passageway  43  of the open link  40 , and the ratchet pin  24  then stands face to face with the wall  44  of the open link  40 , thereby the displacement of the open link  40  toward the engageable position is restricted. In addition, the movable member  35  of which the pin part  39  is engaged with a guide slot  41  of the open link  40  cannot be also displaced into the unlocked position. For this reason, when the unlocking operation of the inside lock button  32  and so forth is performed in the state of  FIG. 5 , the lock lever  30  is, as shown in  FIG. 6 , displaced to the unlocked position U independently while being widened the anti-panic spring  36 , and the movable member  35  is left in the locked position. Thereafter the lock lever  30  is held at the unlocked position U due to elasticity of the over center spring  34  as shown in  FIG. 6 . 
     In the state of  FIG. 6 , when the open lever  27  is released from the door opening operation of the outside open handle  28  or the inside open handle  29  to return to the initial position, the open link  40  moves upward, and the ratchet pin  24  is then got out the passageway  43  (the wall  44 ) of the open link  40 , thereby the restriction of the open link  40  and the movable member  35  toward the unlocked position is released. Therefore, the open link  40  and the movable member  35  can be displaced to the unlocked position due to elasticity of the anti-panic spring  36 . Consequently, it is possible to change the latch device into the unlocked state without performing the secondary unlocking operation by the inside lock button  32  and so forth. 
     As described above, in the present invention, the movable member  35  which is urged by the anti-panic spring  36  is pivotally mounted on the lock shaft  31  for the lock lever  30 . By this means, it is not necessary to prepare the dedicated member for supporting the movable member  35 . In addition, the lock lever  30  is changed between the locked position and the unlocked position by rotating about the lock shaft  31  as the center, therefore, a space where the lock lever  30  is arranged is suitable for accommodating the rotationable member, that is, movable member  35 . Further, owing to the lock lever  30  and movable member  35  are coaxially pivoted the lock shaft  31 , they are formed in the approximately same size as the conventional lock lever. For that reason, it is possible to prevent an increase in size of the door latch device to the utmost.