Abstract:
A vehicle door latch device comprises a pawl lever keeping engagement between a latch and a striker, an output member rotatable in an unlocking direction and in a locking direction by power of a motor and being restored to a neutral position by elasticity of a returning spring when the motor is turned off, a lock lever displaceable between an unlocked position and a locked position by directly receiving rotational movement of the output member, an open link switched between an operative position and a non-operative position by displacement of the lock lever. The open link is directly connected to the lock lever by way of no movable member.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a vehicle door latch device.  
           [0003]    2.Description of the Prior Art  
           [0004]    [0004]FIG. 10 shows a lock mechanism and an opening mechanism of a conventional typical vehicle door latch device (for example U.S. Pat. No. 4,905,532). The prior art latch device comprises a lock lever A for connection to an inside lock button B, an open link C actuated by an open handle D, and a pawl lever E releasing engagement between a latch and a striker. The lock lever A in FIG. 10 is in the unlocked position, and when the open link C is moved down by the actuation of the open handle D, a pressing part F of the open link C comes into contact with a contact part G of the pawl lever E to rotate the pawl lever E, and the door is opened.  
           [0005]    [0005]FIG. 11 shows an prior art actuator unit which moves the lock lever A to the locked position and the unlocked position. The actuator unit comprises a motor H. an output member or a worm wheel J rotated by the motor H, and an intermediate lever K rotated by the contact with the worm wheel J, and the lock lever A is connected to a rotary shaft L of the intermediate lever K. The worm wheel J returns to the neutral position when the motor H is turned off.  
           [0006]    A first problem of the prior art device is caused by the fact that the rotational movement of the worm wheel J is transmitted to the open link C through two members, that is, the intermediate lever K and the lock lever A. If the intermediate lever K and the lock lever A can be constructed by one member, the door latch device can be simplified.  
           [0007]    A second problem of the prior art device is caused by the fact that the lock lever A and the open link C occupy a wide range in the rear surface of a latch housing M. The lock lever A and the open link C positioned at the central portion of the rear surface make the latch device thick in the back-and-forth direction, and often causes the interference with the window glass. Furthermore, the lock lever A and the open link C positioned on the exterior side of the housing M easily receive an illegal access by using a tool which is inserted into the clearance between the window frame and the window glass of the door.  
           [0008]    A third problem of the conventional device is caused by the fact that the lock lever A and the open link C are exposed on the outside of the housing M. The exposed lock lever A and open link C easily receive the illegal access from the outside.  
           [0009]    Furthermore, U.S. Pat. No. 6,059,328 describes a door latch device which comprises a metal base plate ( 18 ) having a main plate ( 18 A) in the left-and-right direction and a sub plate ( 18 B) bent backward from the interior side portion of the main plate, a latch ( 3 ) engageable with a striker ( 2 ), a pawl lever ( 4 ) keeping engagement between the latch and the striker by being engaged with the latch, a synthetic resin striker guide ( 5 ) arranged on the rear side of the main plate and having a striker passage ( 17 ), and a metal mounting plate ( 21 ) having a rear keeping plate which comes into contact with the rear surface of the striker guide. The mounting plate ( 21 ) has a backward bent contact plate ( 21 B) at the interior side portion thereof. An actuator ( 22 ) is fixed between the contact plate ( 21 B) and the sub plate ( 18 B).  
           [0010]    A problem of this prior art device is caused by the fact that the contact plate ( 21 B) does not so much contribute to the improvement of rigidity of the latch device. The strong external force caused by a vehicle accident or the like concentrically acts on the engaged part of the latch and the striker to move the contact plate ( 21 B) of the mounting plate ( 21 ) toward the interior side sometimes. The moving force of the contact plate ( 21 B) is transferred to the sub plate ( 18 B) through the actuator, but the actuator is positioned at a lower position far from the striker passage ( 17 ), and therefore, the external force which is concentrated to the engaged part in the striker passage ( 17 ) cannot well be absorbed.  
           [0011]    Furthermore, the striker guide ( 5 ) also has such a problem that it is large and heavy since it entirely contains the latch and the pawl lever.  
         SUMMARY OF THE INVENTION  
         [0012]    Accordingly, it is an object of the present invention to provide a door latch device having an improved lock lever which functions also as an intermediate lever. The improved lock lever simplifies the door latch device.  
           [0013]    Furthermore, it is another object of the present invention to provide a door latch device having a lock lever and an open link arranged on the interior side of the latch device, where it is difficult to be illegally accessed from the outside.  
           [0014]    Furthermore, it is another object of the present invention to provide a door latch device, in which a lock lever and an open link to be displaced by power of a motor are contained in a housing for shutting off an illegal access from the outside.  
           [0015]    Furthermore, it is another object of the present invention to provide a door latch device capable of well absorbing the external force which concentrically acts on the engaged part of the latch and the striker because of a vehicle accident or the like.  
           [0016]    Furthermore, it is another object of the present invention to provide a door latch device having a striker guide which is small and light, and can be manufactured at a low cost. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a rear view of a door latch device according to the present invention;  
         [0018]    [0018]FIG. 2 is a side view showing an exterior side of the door latch device;  
         [0019]    [0019]FIG. 3 is a side view showing an interior side of the door latch device;  
         [0020]    [0020]FIG. 4 is a side view showing the state where a sub case is removed from the door latch device in FIG. 3;  
         [0021]    [0021]FIG. 5 is a longitudinal sectional rear view of a latch unit of the door latch device;  
         [0022]    [0022]FIG. 6 is a rear view showing a latch and a pawl lever of the latch unit;  
         [0023]    [0023]FIG. 7 is a perspective illustration of a striker guide of the latch unit;  
         [0024]    [0024]FIG. 8 is a perspective illustration of a mounting plate of the latch unit;  
         [0025]    [0025]FIG. 9 is a lateral cross sectional view of the latch unit;  
         [0026]    [0026]FIG. 10 is a perspective illustration of a prior art door latch device; and  
         [0027]    [0027]FIG. 11 is an exploded perspective illustration of the prior art door latch device. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]    [0028]FIG. 1 shows the rear side of the door latch device according to the present invention. A synthetic resin housing  1  of the door latch device comprises a main case  2  facing to the exterior side of a vehicle door and a sub case  3  facing to the interior side of the door. The main case  2  and the sub case  3  are connected and fixed to each other by a screw  5  or the like at a connecting surface  4 . The interior side and exterior side directions shown in the figure are in parallel with the thickness direction of the door which is, hereafter, often referred to as the left-and-right direction.  
         [0029]    The substantially L-shaped main case  2  has a first space  7  extending in the left-and-right direction and a second space  9  extending in the back-and-forth direction. The first space  7  contains a latch unit  6  (FIG. 5), and the second space  9  contains a plurality of members such as a lock mechanism  8 . The second space  9  is positioned on the interior side of the latch device with respect to the vertical central line, in FIG. 1. The interior side of the first space  7  communicates with the front side of the second space  9 , as shown in FIG. 4. The sub case  3  is shaped like a plate or board extending in the back-and-forth direction, and is attached to the interior side surface of the main case  2  as a cover. The front side of the main case  2  is substantially covered by a base plate  51  of the latch unit  6 .  
         [0030]    To the outer surface of the sub case  3 , as shown in FIG. 3, an inner lever  11  is pivoted by a shaft  10  extending in the left-and-right direction. One end of the inner lever  11  is connected to an inside open handle  12  of the door through a wire  13 . As shown in FIG. 1, to the inside (front side) of the rear wall of the first space  7 , an open lever  14  is pivoted by a lever shaft  15  extending in the back-and-forth direction. The exterior side portion  16  of the open lever  14  is projected to the outside of the housing  1  through an opening  17  of the main case  2 , and is operatively connected to an outside open handle  18  of the door. The interior side portion  19  of the open lever  14  is projected to the outside of the housing  1  through an opening  20  of the sub case  3 , and is engageably opposed to the tip end of the inner lever  11 .  
         [0031]    As shown in FIG. 4, in the second space  9 , a plurality of members such as the lock mechanism  8  is contained. A lock lever  21  of the lock mechanism  8  is rotatably supported by a lock shaft  22  extending in the left-and-right direction which is integrally formed to the main case  2 . The lock lever  21  is turned around the lock shaft  22  to be displaced between well known locked and unlocked positions. The lock lever  21  shown in FIG. 4 is positioned in the unlocked position. The lock lever  21  has a projection  25  which is slidably engaged with a triangle-like connecting hole  24  formed in the upper part of an open link  23 . The open link  23  has, at the lower part thereof, an engaging hole  26  with which the interior side portion  19  of the open lever  14  is engaged. The open link  23  has a triangle-like central hole  28  at the middle portion thereof. A guide shaft  27  in the left-and-right direction formed integrally with the main case  2  is slidably engaged with the central hole  28 . The open link  23  substantially is turned around the guide shaft  27  by the displacement of the lock lever  21 . The open link  23  moves up by being guided with the projection  25  and the guide shaft  27  when the open lever  14  is rotated in the door opening direction.  
         [0032]    In the first space  7 , the latch unit  6  is contained, but in FIG. 4, only a pawl lever  29  and a pawl pin  30  of the latch unit  6  are shown by imaginary lines. The pawl lever  29  releases the latch unit  6  so as to open the door when rotated, which is described later.  
         [0033]    The lock lever  21  shown in FIG. 4 is positioned at the unlocked position. In the unlocked state, a contact edge  31  of the open link  23  is engageably opposed to the pawl lever  29  so that the contact edge  31  of the open link  23  rotates the pawl lever  29  to open the door when the open link  23  is moved up by opening rotation of the open lever  14 . When the lock lever  21  is displaced to the locked position, the open link  23  is rotated counterclockwise, and the contact edge  31  is separated from the pawl lever  29 . Accordingly, in the locked state, even if the open link  23  is moved up, the pawl lever  29  does not rotate, and the door is not opened.  
         [0034]    The lock lever  21  integrally has a connecting part  32  which is exposed to the outside through a window hole  33  of the sub case  3 , as shown in FIG. 3, and the connecting part  32  is connected, through the window hole  33 , to a wire  35  which leads to an inside lock button  34  of the door.  
         [0035]    A motor  36  is contained in the upper part of the second space  9 . The rotary shaft of the motor  36  supports a cylindrical worm  37  with which a worm wheel  38  is meshed. A gear wheel  39  having five gear teeth is fixed to the rotary shaft of the worm wheel  38 , and is meshed with a geared portion  40  formed in the lock lever  21 . The worm wheel  38  is kept at the neutral position by the elasticity of a returning spring  41  when the motor  36  is not energized, and it can be rotated both in the counterclockwise (locking) direction and in the clockwise (unlocking) direction from the neutral position by the power of the motor  36 . The structure from the motor  36  to the geared portion  40  is described in detail in GB 2,357,548 A, and there fore, here, it will simply be described below. In the state of FIG. 4, when the gear wheel  39  rotates counterclockwise, the lock lever  21  is rotated clockwise to be displaced from the unlocked position to the locked position, and after that, even if the worm wheel  38  is rotated clockwise by the elasticity of the returning spring  41  to be returned to the neutral position, the lock lever  21  is kept at the locked position as it is. When the worm wheel  38  rotates clockwise from the neutral position by the motor power, the lock lever  21  is restored from the locked position to the unlocked position, and after that, even if the worm wheel  38  is rotated counterclockwise by the elasticity of the returning spring  41  to be returned to the neutral position, the lock lever  21  is kept at the unlocked position as it is. Furthermore, when the worm wheel  38  is positioned at the neutral position, the rotation of the lock lever  21  is not transferred to the geared portion  39 .  
         [0036]    The lock lever  21  according to the present invention connects the worm wheel  38  (geared portion  39 ) and the open link  23 . Here, the worm wheel  38  is defined as a member which is restored to the neutral position by the elasticity of the neutral returning spring  41  when the motor  36  is not energized. Furthermore, the open link  23  is defined as a member which can transfer the opening operational force of the open handles  12  and  18  to the pawl lever  29 . The lock lever  21  of the present invention has such a characteristic, and therefore, it can serve as both the lock lever A and the intermediate member K shown in FIGS. 10 and 11.  
         [0037]    Furthermore, it should be noted that the lock lever  21  is rotatably supported by the lock shaft  22  having an axial line in the left-and-right direction. Therefore, the lock lever  21  can easily be attached to the rearwardly extending side wall of housing  1  positioned in the interior side of the latch device, and the anti-theft performance of the lock lever  21  is improved. That is, the interior side of the door latch device has less danger of receiving an illegal access from the outside than the exterior side. Additionally, in the case of the present invention, the lock lever  21  and the open link  23  are arranged on the interior side of the door latch device, and therefore, the door latch device becomes thin in the back-and-forth direction on the central and exterior side portions. Consequently, the degree of freedom when attaching the door latch device to the door is improved.  
         [0038]    Furthermore, the second space  9  accommodating the lock lever  21  and the open link  23  extends in the back-and-forth direction, and therefore, it can easily be surrounded by the main case  2  and the sub case  3 . Therefore, the open link  23  and the lock lever  21  in the second space  9  can effectively be shut off against the illegal access from the outside. In addition, the motor  36  can also be contained in the second space  9 , and therefore, the connection between the motor  36  and the lock lever  21  can easily be performed, and a third space for the motor  36  becomes unnecessary.  
         [0039]    In FIG. 4, to the upper part of the second space  9 , a key lever  42  is attached by a key shaft  43  which is exposed to the outside through a cylindrical part  44  of the main case  2  to be connected to a door key cylinder through a rod or the like. Furthermore, the door key cylinder may also be provided in the cylindrical part  44 . A pin  45  provided at the end part of the key lever  42  is engaged with a forked part  47  formed at one end of a connecting lever  46 . A pin  48  at the other end of the connecting lever  46  is engaged with an engaging hole  49  formed in the upper part of the lock lever  21 . Reference numeral  50  denotes a printed circuit board.  
         [0040]    [0040]FIG. 5 shows the latch unit  6  to be contained in the first space  7 . The metal base plate  51  of the latch unit  6  is approximately L-shaped when seen from the upper side, as shown in FIG. 9, and is constructed by a main plate  52  extending in the left-and-right direction and a sub plate  53  bent backward from the interior side portion of the main plate  52 . When the latch unit  6  is contained in the first space  7 , the front side opening of the first space  7  is substantially closed by the main plate  52 , and the sub plate  53  is positioned approximately on the same plane as the sub case  3  to close the interior side of the first space  7 .  
         [0041]    To the rear side of the main plate  52 , a well known latch mechanism having a latch  54  and the pawl lever  29  is attached. A latch shaft  56  of the latch  54  and a pawl shaft  57  of the pawl lever  29  extend in the back-and-forth direction. The sub plate  53  has a striker gate  53 A in the back-and-forth direction into which a striker  58  fixed to the vehicle body enters, and the main plate  52  has a lateral U-shaped shaped striker channel  59  communicated with the striker gate  53 A. The striker  58  which enters the striker channel  59  by closing the door is engaged with the latch  54 . The engagement between the latch  54  and the striker  58  is kept by the engagement of a pawl  55  of the pawl lever  29  with the latch  54 .  
         [0042]    In the latch device, the interior and exterior sides of the latch device are distinguished by the position of the striker gate  53 A into which the striker  58  enters when the door is closed, which striker gate must be formed on the interior side of the latch device.  
         [0043]    On the rear side of the latch mechanism, a synthetic resin striker guide  60  shown in FIG. 7 is arranged. The striker guide  60  is shaped like a lateral “U ”, and has an upper wall  61  and a lower wall  62  between which a striker passage  63  having the same shape as the striker channel  59  is formed. To the interior side portion of the striker guide  60 , upper and lower struts  64  and  65  which come into contact with the main plate  52  are integrally formed. The striker guide  60  does not come into contact with the main plate  52  at a part other than the struts  64  and  65 , and a clearance  66  (FIG. 9) formed between the striker guide  60  and the main plate  52  accommodates the latch mechanism. The lower wall  62  integrally has an elastic part  67  which elastically comes into contact with the striker  58 . To the exterior side portion of the striker passage  63 , a rubber stopper  68  is attached.  
         [0044]    The latch and pawl shafts  56  and  57  fix to the main plate  52  a metal mounting plate  69  for keeping, protecting and reinforcing the striker guide  60 . The mounting plate  69  comprises a rear keeping plate  69 A which covers the rear side of the striker guide  60 , an upper keeping plate  70  which is angled to extend forward from upper edge of the rear keeping plate  69 A so as to be overlapped onto the upper surface of the upper wall  61  of the striker guide  60 , and a lower keeping plate  71  which is angled to extend forward from the lower edge of the rear keeping plate  69 A so as to be overlapped onto the under surface of the lower wall  62  of the striker guide  60 . The mounting plate  69  further comprises a plurality of bent legs  73  to be inserted into a plurality of engaging holes  72  formed in the striker guide  60 , and the striker guide  60  is kept at a specified position by the mounting plate  69 .  
         [0045]    The rear keeping plate  69 A has a backward bent contact plate  74  which is positioned adjacent to the sub plate  53 , as shown in FIG. 9, at the interior side portion thereof. The contact plate  74  is overlapped onto the striker passage  63  in the back-and-forth direction. When a strong external force to be caused by a vehicle accident or the like is applied on the engaged part of the latch  54  and the striker  58 , the contact plate  74  comes into contact with the sub plate  53  and keeps the preferable positions of the latch  54  and the pawl lever  29 . The contact plate  74  and the sub plate  53  can be fixed to each other by fixing means such as welding, screwing, or hook engaging.  
         [0046]    The striker guide  60  does not come into direct contact with the latch and pawl shafts  56  and  57 , and is substantially arranged between the shafts  56  and  57 . Therefore, the striker guide  60  is extremely small and light, and can be manufactured at a low cost, when compared with a conventional synthetic resin latch body.  
         [0047]    The second space  9  where a plurality of operating members such as the lock mechanism  8  are contained is arranged on the interior side with respect to the latch shaft  56 , as shown in FIG. 1.  
         [0048]    In FIGS. 3 and 4, on the inside of the sub case  3 , a cancel lever  75  is supported by the guide shaft  27 . The cancel lever  75  has a bent part  76  which is engageably with the pawl pin  30 , and a pressing piece  77  which is engageably with the side of the open link  23 . When the door is closed in the locked state, the pawl pin  30  is moved upward to rotate the cancel lever  75  clockwise, and the pressing piece  77  then comes into contact with the open link  23  to rotate the open link clockwise, and consequently, the lock lever  21  is restored from the locked position to the unlocked position.