Patent Publication Number: US-8109542-B2

Title: Door latch device for a vehicle

Description:
This application claims priority from Japanese Application Serial No. 2006-183574 filed Jul. 3, 2006. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a door latch device for a vehicle comprising a door which can be opened and closed about a hinge shaft, the device enabling the door to be held in a closed position. 
     In JP2005-68722A, a hatch door is pivotally secured at the rear part of a vehicle body about a hinge shaft at the top to open and close up and down. A door latch device for holding the hatch door in a closed position comprises an engagement portion which engages with a striker of the vehicle body to hold the hatch door in the closed position, and a driving portion for releasing engagement of the engagement portion from the striker by a motor to enable the hatch door to open. 
     In an emergency in which an electric system for the motor breaks down, the hatch door has to be opened by an operating portion at the interior of the vehicle. 
     In the door latch device, if the motor for the driving portion in the door latch device is not driven, it is necessary to open a cover over a trim on the interior of the vehicle to work the operating portion, which is troublesome. 
     SUMMARY OF THE INVENTION 
     In view of the disadvantages in the prior art, it is an object of the invention to provide a door latch device for a vehicle, easily opening a door at the interior of a vehicle if a motor is not driven. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the invention will become more apparent from the following description with respect to embodiments as shown in accompanying drawings wherein: 
         FIG. 1  is a vertical sectional side view of the lower part of a hatch door to which the present invention is applied; 
         FIG. 2  is a rear view of the latch device; 
         FIG. 3  is a front view thereof; 
         FIG. 4  is an exploded perspective view of a latch device according to the present invention; 
         FIG. 5  is a rear perspective view of the latch device; 
         FIG. 6  is a front perspective view of the match device; 
         FIG. 7  is a horizontal sectional view taken along the line VII-VII in  FIG. 2 ; 
         FIG. 8  is a horizontal sectional view taken along the line VIII-VIII in  FIG. 3 ; 
         FIG. 9  is a horizontal sectional view taken along the line IX-IX in  FIG. 3 ; 
         FIG. 10  is a rear view of the latch device from which a cover and a base plate are removed; 
         FIG. 11  is a rear view of the latch device from which the cover and base plate are removed; 
         FIG. 12  is an enlarged front view of the main part; 
         FIG. 13  is an enlarged rear view thereof; 
         FIG. 14  is a perspective view of the latch device from which a cover and a base plate are removed; 
         FIG. 15  is a perspective view of the latch device from which the base plate is removed; and 
         FIG. 16  is a perspective view of the latch device from which the housing is removed. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     In the following description, the left side in  FIG. 1  is the front of a vehicle, and the right side is the rear of the vehicle. The back in  FIG. 2  and the front in  FIG. 3  are the front of a latch device, and the front in  FIG. 2  and the back in  FIG. 3  are the rear. 
     In  FIGS. 1-3 , the latch device  1  comprises an engagement portion  6  for holding in a closed position a hatch door  3  which opens and closes up and down about a hinge shaft (not shown) at the rear of the vehicle; and a driving portion  7  for releasing the engagement portion  6 . At a lower part of an inner panel  31  of the hatch door  3 , the engagement portion  6  is exposed from the hatch door  3  and the driving portion  7  is stored in the hatch door  3 . 
     The latch device in  FIG. 1  is tilted, but may be mounted vertically depending on the shape and a closing direction of the hatch door and mounting position of a striker  4  described later. 
     The engagement portion  6  engages with an engagement rod  41  of the inverted-U shaped striker  4  fixed to a vehicle body  2  thereby holding the hatch door  3  in a substantially vertical closed position in  FIG. 1 . The outer surface of the engagement portion  6  which projects from the inner panel  31  of the hatch door  3  is covered with a synthetic-resin cover  61  to improve appearance. For better understanding, the cover  61  is shown only in  FIGS. 1 ,  2 ,  4  and  7  and omitted in the other views. 
     In  FIG. 4 , the engagement portion  6  comprises a metal base plate  8  fixed to the inner panel  31  of the hatch door  3 ; a latch  10  which can engage with the striker  4 ; a ratchet  11  which can engage with the latch  10 ; a latch spring  12  for forcing the latch  10  in an opening direction or a clockwise direction in  FIGS. 2 ,  10  and  11 ; a ratchet spring  13  for forcing the ratchet  11  in an engagement direction or an counterclockwise direction in  FIGS. 2 ,  10  and  11 ; and a turning-position sensor  23  for detecting a rotational position of the latch  10 . 
     The driving portion  7  comprises an upper part of the synthetic-resin housing  15 ; a synthetic-resin cover  16  for closing an upper rear part of the housing  15 ; a motor  17 ; a worm  18  fixed to a shaft  171  of the motor  17 ; and a worm wheel  19  which meshes with the worm  18 . 
     Mounting portions  81 , 82  of a base  83  projecting from the inner panel  31  of the hatch door  3  is coupled to a mounting surface  32  at the lower part of the inner panel  31  with bolts  5  and female threads  81   a , 81   b , 82   a  which engage with the bolts  5 . The mounting surface  32  is perpendicular to an opening direction A of the hatch door  3  in  FIG. 1 , so that the base plate  8  is fixed to the hatch door  3 . At the lower side of the middle of the base  83 , a groove  84  in which the striker  4  engages when the hatch door  3  is closed is formed along a striker engagement direction B or a direction opposite to a closing direction of the hatch door  3 . 
     The right and left mounting portions  81 , 82  have surfaces perpendicular to the opening direction of the hatch door  3  and are spaced apart from each other along a direction of an axis of a hinge shaft. In the right and left mounting portions  81 , 82 , there are the female threads  81   a , 81   b , 82   a  in which the bolt  5  extending perpendicular to the mounting surface  32  of the hatch door  3  and the surfaces of the mounting portions  81 , 82  or in the opening direction A of the hatch door engages. 
     To fix the latch device  1  to the hatch door  31  while the right and left mounting portions  81 , 82  of the base plate  8  is pressed on the mounting surface  32  of the inner panel  31 , the bolt  5  is inserted in a bore (not shown) of the mounting surface  32  and engaged with the female threads  81   a , 81   b , 82   a  to allow the mounting portions  81 , 82  to be joined to the mounting surface  32  of the inner panel  31 . 
     In  FIGS. 7 and 8 , the left mounting portion  81  (right in  FIG. 8 ) is broader than the right mounting portion  82  (left in  FIG. 8 ). The left mounting portion  81  has the two female threads  81   a , 81   b , while the left mounting portion  82  has the one female thread  82   a.    
     In this embodiment, the number of the female threads in the left mounting portion  81  is larger than that of the female threads in the right mounting portion  82 . But the present invention is not limited to this, and the number of female threads in the right and left mounting portions  81 , 82  may be equal to each other. As shown by a dotted line in  FIG. 4 , an upward bent portion  88  may be provided on a connecting portion  87  between the right and left mounting portions  81  and  82  to increase rigidity of the base plate  8 . The mounting portion  82  is smaller than the mounting portion  81 . If the portions  82  and  83  have the same size, rigidity of the base plate  8  can be improved. 
     In  FIGS. 7 and 8 , a straight line L 1  between the female thread  81   a  of the left mounting portion  81  and the female thread  82   a  of the right mounting portion  82  is parallel with the hinge axis C. The female thread  81   b  of the left mounting portion  81  is deviated from the straight line L 1 . 
     A binding device of the present invention comprises the bolts  5  which engage in the female threads  81   a , 81   b , 82   a  of the mounting portions  81 , 82 , but the present invention is not limited to those. For example, the binding device may comprise weld bolts fixed to the mounting portions  81 , 82  by welding and nuts which engage with the weld bolts; weld nuts fixed to the mounting portions  81 , 82  by welding and bolts which engage with the weld nuts; bores of the mounting portions  81 , 82  and tapping screws which engage in the bores; or weld bolts welded to the surface of the inner panel  31  and nuts which engage with the weld bolts put in bores of the mounting portions  81 , 82 . 
     The mounting portions  81 , 82  are formed at the sides of the base  83  of the base plate  8 , and side portions  85 , 85  bent at right angles with respect to the base  83  are provided to increase rigidity of the base  83 . 
     A housing  15  faces the base  83  and is fixed to the front face of the base plate  8  between the side portions  85  and  85 . 
     At the lower middle part of the housing  15 , there is a striker-fitting groove  151  which is coincident with the striker-fitting groove  84  of the base plate  8 . On the rear surface of the housing  15 , there are a latch-connecting region  152  on which the latch  10  fits; a ratchet-connecting region  153  on which the ratchet  11  fits; a motor-connecting region  154  on which the motor  17  fits; a worm-wheel-connecting region  155  on which the worm wheel  19  fits; and a spring-connecting region  156  on which the ratchet spring  13  and a turning-position sensor  23  fit. 
     The latch-connecting region  152  is formed at a left lower part of the housing  15 . The motor-connecting region  154  is above the latch-connecting region  152 . The ratchet-connecting region  153  is at a right lower part of the housing  15  and at right side of the latch-connecting region  152 . The worm-wheel-connecting region  155  is above the ratchet-connecting region  153  and at right side of the motor-connecting region  154 . The spring-connecting region  156  is formed almost like a triangle between the motor  17  and ratchet  10  by tilting the motor  17  as described later. 
     In  FIGS. 10 and 11 , a straight boarder line L 2  passes through the striker-fitting grooves  84 , 151  along a striker-fitting direction. In the base plate  8  and housing  15 , a left side or one side of the boarder line is called the first area  15 A, while a right side or the other side thereof is called the second area  15 B. The first area  15 A comprises the latch-connecting region  152 , motor-connecting region  154 , spring-connecting region  156  and the mounting portion  81  fixed to the mounting surface  32  of the hatch door  3  with the two bolts  5 . The second area  15 B comprises the ratchet-connecting region  153 , the worm-wheel-connecting region  155 , and the right portion  82  fixed to the mounting surface  32  of the hatch door  3  with the one bolt  5 . 
     The left mounting portion  81  in the first area  15 A including the latch  10  is fixed to the mounting surface  32  of the hatch door  3  with the two bolts  5 , so that the left mounting portion  81  is firmly fixed to the mounting surface  32 . The bolts  5  for fixing the left mounting portion  81  to the mounting surface  32  of the hatch door  3  is more in number than the bolts  5  for fixing the right mounting portion  82  to the mounting surface  32  of the second area  15 B, so that the left mounting portion  81  of the first area  15 A to which load is likely to act can be firmly fixed to the mounting surface  32 . 
     Between the ratchet-connecting region  153  and the worm-wheel-connecting region  155  of the housing  15 , a radial-bearing region  157  which rotatably supports the entire circumference of the end of the worm  18  is integrally formed. In  FIGS. 9 and 13 , the radial-bearing region  157  comprises a recess  157   a  in which the end of the worm  18  engages, and a holding portion  157   b  which obliquely faces the recess  157   a . In  FIG. 9 , there is a rapping hole  157   c  on the surface facing the holding portion  157   b  in the housing  15  when the holding portion  157   b  is molded from synthetic resin. 
     The end of the worm  18  axially extends between the recess  157   a  and the holding portion  157   b , so that it is rotatably supported in the radial-bearing region  157 . It prevents the worm  18  from radially loosening and supports the end of the worm  18 . As a result, when the opening lever  14  crosses the worm  18  as described later, even if the cover  16  cannot partially hold the end of the worm  18  radially by the opening lever  14 , the end of the worm  18  is prevented from loosening radially by the recess  157   a  and the holding portion  157   b  to enable the end to be supported rotatably. 
     The back plate  9  is fixed to the front lower part of the housing  15  and fixed to the base plate  8  together with the housing  15 , so that the back plate  9  fits between the right and left side portions  85  and  85 , and the right and left projections  92 , 92  at each side are disposed in recesses  86 , 86  of the side portions  85 , 85  of the base plate  8 . At the lower part of the back plate  9 , the striker-fitting groove  91  engages with a flange  151   a  surrounding the striker-fitting groove  151  of the housing  15 . 
     At the upper part of the back plate  9  or above the striker-fitting groove  91 , a flange  93  extends in the hinge-axis direction C and is bent at almost right angles to extend forwards or in the pivot direction D, crossing an extension of the striker-fitting groove  91 . A holding portion  94  is bent upward at almost right angles at the front end of the flange  93 . 
     The flange  93  increases rigidity around the bottom of the striker-fitting groove  91  of the back plate  9 . As shown in FIGS.  3 , 6  and  8 , the flange  93  engages between the side portions  85  and  85 . 
     When load is applied to the latch device  1  in an opening direction, each edge of the flange  93  of the back plate  9  contacts the side portions  85 , 85  of the base plate  8  thereby preventing deformation of the back plate  9  and base plate  8  effectively not to disengage the latch  10  from the ratchet  11 . So, engagement strength of the latch  10  and ratchet  11  can be improved, With the flange  93 , engagement between the latch  10  and the ratchet  11  can be improved by preventing deformation in the pivot direction D. 
     A projection  92  of the back plate  9  engages in a recess  86  of the base plate  8  to prevent the back plate  9  and the base plate  8  from moving to each other up and down. Thus, it can be kept at minimum to deform the base plate  8  and the back plate  9  for supporting the latch  10  and the ratchet  11 , thereby increasing engagement strength of the latch  10  and the ratchet  11 . 
     The holding portion  94  contacts the front surface of the housing  15 . An opening  95  in the middle of the holding portion  94  engages with a projection  158  of the housing  15  thereby reinforcing the front of the housing  15 . 
     The latch  10  is pivotally secured to the latch-connecting region  152  between the base  83  of the base plate  8  and the lower part of the housing  15  with a latch pivot  20  which extends in a direction perpendicular to the opening direction of the hatch door  3  or in the pivot direction D almost perpendicular to the striker-fitting direction B and the hinge-axis direction C. 
     When the hatch door  3  is open, the latch  10  is in an open position where the latch  10  disengages from the striker  4  in  FIG. 11 . When the hatch doer  3  is closed, the latch  10  engages with the engagement rod  41  of the striker  4  which comes in the striker-fitting grooves  84 , 91 , 151  to turn in an counterclockwise direction by 90 degrees from the open position against the force of the latch spring  12  around the latch pivot  20  to a full-latch position in  FIG. 10 . 
     The ratchet  11  is pivotally secured with a ratchet pivot  21  in parallel with the latch pivot  20  to the ratchet-connecting region  153  between the base  83  of the base plate  8  and the lower part of the housing  15 . When the hatch door  3  is closed, a claw  111  of the ratchet  11  engages with a claw  101  of the latch  10  to prevent the latch  10  from turning in the open direction thereby holding the hatch door  3  in the closed position. The ratchet  11  turns against the force of the ratchet spring  13  to a release position in  FIG. 11  to allow the latch  10  to turn freely to the open position and to enable the hatch door  3  to open. When the ratchet  11  is in an engagement position, the lower end of the ratchet  11  contacts a stopper  25  made of rubber in the housing  15 . 
     At the upper end of the ratchet  11 , there is an engagement portion  113  which can engage with the other end  132  of the ratchet spring  13  of the spring-connecting region  156  as described later. At the upper end of the ratchet  11 , there is an emergency-operating portion  112  which is exposed to the interior of the vehicle through an opening  150  of the housing  15 . 
     The emergency-operating portion  112  is surrounded by an elastic member  24  such as rubber. The elastic member  24  reduces sound when the opening lever  14  strikes on the emergency-operating portion  112 . The elastic member  24  also acts as a stopper  25  for limiting rotation of the ratchet  11 . The elastic member  24  may be molded from resin together with the ratchet  11 . 
     When the hatch door  3  is in the closed position, the opening lever  14  is released by the motor  17  to allow the side of the opening lever  14  to contact the elastic member  24  of the emergency-operating portion  112  to enable the ratchet  11  to be released. 
     If trouble in an electric system and others makes it impossible for the ratchet  11  to be released by the motor  17  in an emergency, the emergency-operating portion  112  exposed inside is manually operated in the interior of the vehicle without removing the trim of the hatch door, so that the ratchet  11  is disengaged from the latch  10  to allow the hatch door  3  to open quickly. 
     The emergency-operating portion  112  plays two roles of transmitting releasing of the opening lever  14  to the ratchet  11  and of working in an emergency thereby simplifying the shape of the ratchet  11  and entire structure. 
     The emergency-operating portion  112  is set not to protrude from the flange  93  of the back plate  9  in the interior. Thus, the emergency-operating portion  112  does not work mistakenly by hitting baggage directly onto the emergency-operating portion  112  in the interior. 
     The emergency-operating portion  112  has a recess  112   a  in which a rod-like tool such as a screwdriver can be put. The tool is inserted in the recess of the emergency-operating portion  112  to allow the ratchet  11  to be released easily. 
     The latch pivot  20  and ratchet pivot  21  pass through the base plate  8 , housing  15  and back plate  9 . The front ends of the pivots  20 , 21  are bent on the back plate  9 , and the rear ends are bent around the end of the base plate  8 . While the housing  15  is held between the base plate  8  and the back plate  9 , the base plate  8 , housing  15  and housing  9  are fixed to one another. 
     In  FIG. 7 , a striker-engaging part E of the latch  10  is set to coincide with a straight line L 1  which passes through the centers of the female thread bores  81   a , 82   a  of the mounting portions  81 , 82  seen from the striker-fitting direction B. 
     Furthermore, in  FIG. 8 , an engagement part F in which the claw  101  of the latch  10  engages with the claw  111  of the ratchet  11  is set to coincide with the straight line L 1 . 
     Accordingly, in case that opening load acts between the latch device  1  and the striker  4  when the hatch door  3  is closed, load W which acts to a bound part between the base plate  3  and the hatch door  3  via the latch  10  and the ratchet  11  acts straight to the bolts  5  engaging with the female threads  81   a , 82   a , thereby reducing deformation of the mounting surface  32  of the inner panel  31  in the hatch door  3  and the mounting portions  81 , 82  of the base plate  8  at minimum and increasing strength of the latch device  1 . 
     For example, if the load W obliquely acts onto the bolts  5  or to a position away from the straight line L 1 , the surface  31  and the mounting portions  81 , 82  are deformed obliquely thereby decreasing strength. 
     The worm wheel  19  is pivotally secured to the worm-wheel-connecting region  155  between the upper end of the housing  15  and the cover  16  with a worm-wheel pivot  22  in parallel with the latch pivot  20  and is always forced to a neutral position by a spring (not shown) around the worm-wheel pivot  22 . 
     In  FIGS. 10 and 11 , the motor  17  is disposed in the motor-connecting region  154  between the upper end of the housing  15  and the cover  16  such that a shaft  171  is inclined. That is, the axis L 3  of the shaft  171  goes between the ratchet pivot  21  and the worm-wheel pivot  22  and crosses obliquely with respect to the boarder line L 2 . 
     The worm  18  reversibly meshes with a gear  191  on the outer circumference of the worm wheel  19  and rotates by the motor  17  to allow the worm wheel  19  to turn from the standby position in a releasing direction or in an counterclockwise direction in  FIGS. 10 ,  11  and  13 . The worm wheel  19  rotates in the releasing direction and the turning-position sensor  23  detects an open position of the latch  10 , so that the motor  17  stops. The worm wheel  19  returns to the neutral position by the spring and stops. 
     The opening lever  14  is pivotally secured with the ratchet pivot  21  coaxial with the ratchet  11  such that it can swing separately from the ratchet  11 . The opening lever  14  crosses the axis L 3  of the shaft  171  over the worm  18 . A sector gear  141  of the opening lever  14  meshes with a smaller gear  192  of the worm wheel  19 . 
     When the hatch door  3  is closed, the worm wheel  19  turns from the neutral position in the releasing direction by the motor  17 . Thus, the opening lever  14  swings from the standby position in  FIG. 10  in the releasing direction or clockwise direction in  FIG. 10  to the releasing position in  FIG. 11 . The side edge of the opening lever  14  contacts the emergency-operating portion  112  via the elastic member  24  on the outer circumferential surface of the emergency-operating portion  112  to let the ratchet  11  swing from the engagement position to the releasing position. Specifically, by a switch S on the outer surface of the hatch door  3  when the hatch door  3  is closed, the motor  17  is driven, and power of the motor  17  is transmitted to the ratchet  11  via the opening lever  14  and the emergency-operating portion  112  thereby having the ratchet  11  released so that the hatch door  3  can be opened. 
     The hatch door  3  is opened to make the motor  17  to stop. Thus, the worm wheel  19  returns to the neutral position and the opening lever returns to the standby position. 
     When the opening lever  14  and the ratchet  11  are in the standby position and in the engagement position respectively, the side edge of the opening lever  14  contacts the elastic member  24  about the emergency-operating portion  112  of the ratchet  11 . Accordingly, the opening lever  14  is prevented from loosening caused by backlash of the engagement between the sector gear  141  of the opening lever  14  and the smaller gear  192  of the worm wheel  19 . 
     The ratchet spring  13  comprises a coil spring, a coiled part of which is wound around an axial part  159   a  of the spring-connecting region  156 . One end of the spring  13  is fixed to an engagement portion  159   b  near the axial portion  159   a , while the other or free end  132  engages with an engagement portion  113  of the ratchet  11  in the pivot direction D thereby applying force in an engagement direction to the ratchet  11 . The coiled portion  131  is disposed out of an operation area of the ratchet  11  and the opening lever  14  not to contact the ratchet  11  and the opening lever  14 . 
     By such arrangement, the latch  10 , the ratchet  11 , the motor  17 , the worm wheel  19  and the opening lever  14  are gathered at optimum position thereby reducing the sizes of the striker-fitting direction B and hinge-axis direction C and thickness of the pivot direction D to make the whole size of the latch device  1  smaller. 
     Particularly, the motor  17  is tilted in the motor-connecting region  154 , the ratchet spring  13  can be easily connected to the spring-connecting region  156  between the motor  17  and the latch  10 . Also, a space between the motor  17  and the latch  10  can be efficiently employed for mounting the ratchet spring  13  to make the latch device  1  smaller. 
     The ratchet spring  13  is not overlapped on the latchet  11  and the opening lever  14  in the pivot direction D thereby reducing thickness of the pivot direction of the latch device  1 . Furthermore, the other end  132  of the ratchet spring  13  engages with the engagement portion  113  of the ratchet  11  in the pivot direction D, thereby achieving firm engagement of the other end  132  of the ratchet spring  13  with the ratchet  11 . 
     The turning-position sensor  23  is disposed in the spring-connecting region  156  and a detecting portion  231  is in sliding contact with the outer circumferential surface of the latch  10  to detect a turning position of the latch  10 . 
     Then, how to assemble the latch device  1  will be described. 
     First, the front ends of the latch pivot  20  and the ratchet pivot  21  are bent and fixed to the back plate  9 . Thereafter, the back plate  9  contacts the front surface of the housing  15  to allow the latch pivot  20  and ratchet pivot  21  to project from the rear surface of the housing  15 . 
     In  FIG. 14 , the latch  10 , ratchet  11 , latch spring  12 , ratchet spring  13 , opening lever  14 , motor  17 , worm wheel  19  and turning-position sensor  23  are mounted to the housing  15  and the upper rear surface of the housing  15  is closed by the cover  16 . Then, the base plate  8  is mounted to the lower rear surface of the housing  15  and the rear ends of the latch pivot  20  and ratchet pivot  21  which project from the base plate  8  are bent and fixed. So the latch device  1  is finally assembled. 
     The foregoing merely relate to embodiments of the invention. Various changes and modifications may be made by a person skilled in the art without departing from the scope of claims, as below: 
     (i) The latch device  1  may be applied to other doors such as a side door which opens and closes about a vertical hinge shaft to a vehicle body. 
     (ii) The latch device  1  may be mounted to the vehicle body, while the striker  4  may be mounted to a door. 
     (iii) The base plate  8  is integrally formed with the housing  15 , or the housing  15  may be integrally formed with the back plate  9 .