Patent Publication Number: US-9428935-B2

Title: Driving device of vehicle door latch unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2014-178598 filed in Japan on Sep. 2, 2014. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicle door latch unit, and in particular, to a driving device of the latch unit. 
     2. Description of the Related Art 
     A conventionally well known latch unit includes a latch that engages with a striker and a ratchet that engages with the lath and holds the engagement between the latch and the striker, and in the latch unit, a driving device (a device having an automatic closing function, hereinafter also referred to as “automatic closing mechanism”) that rotates the latch by a motor power from a half latch position to a full latch position is associatively connected to the latch, and a driving device (a device having an automatic releasing function, hereinafter also referred to as “automatic releasing mechanism”) that rotates the ratchet by a motor power in a door opening direction (a direction in which the engagement with the latch is released) to bring a door into an openable state is associatively connected to the ratchet (for example, see Japanese Patent Application Laid-open No. 2014-009477, and see Japanese Patent Application Laid-open No. 2005-248485 for a latch unit including an automatic closing mechanism). 
     For control of the driving devices, signals from a plurality of switches are used. The plurality of switches are broadly classified into a driven side switch group that detects states (positions) of the latch and ratchet of the latch unit and a driving side switch group that detects a state (position) of a driving mechanism that rotates the latch and ratchet by a motor power. 
     A latch switch that detects an unlatch position, a half latch position, a full latch position, and the like of the latch and a ratchet switch that detects, for example, whether or not the ratchet has rotated to a position where the ratchet is able to engage with the latch correspond to the driven side switch group. A gear switch or the like that detects, for example, whether the driving mechanism, such as a sector gear, which is rotated by the motor power, is at a neutral position (initial position) or at an operation completion position corresponds to the driving side switch group. 
     Types and the numbers of the plurality of switches that are used vary, and methods of processing the signals from the plurality of switches also vary, depending on design concepts of the latch unit/driving mechanism, and in any case, durability of the switches and downsizing the cam body for turning the switches ON or OFF have been ongoing problems in the designing. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     According to one aspect of the present invention, there is provided a driving device of a door latch unit, the driving device including: a neutral switch that switches over from ON to OFF, when an automatic closing function by a motor is operated and a first cam surface is released from a contact with the neutral switch; and a gear detection switch that switches over from ON to OFF, when an automatic closing function by the motor is operated and a second cam surface is released from a contact with the gear detection switch, wherein the operation of the automatic closing function by the motor is configured to be initiated by switch-over of a ratchet switch of the door latch unit from OFF to ON, the operation of the automatic closing function by the motor is configured to be ended by switch-over of the neutral switch from OFF to ON, and the gear detection switch is configured to switch over from OFF to ON by coming into contact with the second cam surface again when the automatic releasing function by the motor is operated. 
     The second cam surface according to another aspect of the present invention may be set at a height where the second cam surface does not come into contact with the neutral switch and the second cam surface may extends from an end portion of the first cam surface. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a latch unit of a door latch device to which a driving device, which is an embodiment of the present invention, is applied; 
         FIG. 2  is a rear view of the latch unit of  FIG. 1  with a part thereof being omitted; 
         FIG. 3  is a rear view illustrating a state where a switch assembly of a driven side switch group has been installed in a latch body of the latch unit; 
         FIG. 4  is an exploded view of a rear face side of the latch unit; 
         FIG. 5  is a front view of a sector gear of the driving device attached with a gear interlocking cam body; 
         FIG. 6  is a front view illustrating the gear interlocking cam body and a switch assembly of a driving side switch group; 
         FIG. 7  is a front view illustrating the switch assembly of the driving side switch group; 
         FIG. 8  is an enlarged view of the gear interlocking cam body; and 
         FIG. 9  is a time chart. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will be described. As illustrated in  FIG. 1 , onto a latch body  10  of a latch unit (latch device), the latch body  10  being formed of a synthetic rein or the like, a latch  12  is pivotally supported by a latch shaft  11  and a ratchet  14  is pivotally supported by a ratchet shaft  13 . The latch  12  has an engagement groove  17 , a half latch engagement portion  18 , and a full latch engagement portion  19 . The engagement groove  17  is formed from an outer peripheral surface of the latch  12  towards the latch shaft  11  and has a width that is able to accommodate a striker  15 . The half latch engagement portion  18  is formed, as illustrated in  FIG. 1 , at a portion positioned on a left side of an opening edge portion of the latch  12  in the engagement groove  17 . This half latch engagement portion  18  is configured to lock the latch  12  by engaging with the ratchet  14  when the latch  12  is caused to be rotated in a clockwise direction and brought to a half latch position. The full latch engagement portion  19  is formed as a concave portion on the outer peripheral surface of the latch  12 . This full latch engagement portion  19  is configured to lock the latch  12  by engaging with the ratchet  14  when the latch  12  is rotated in the clockwise direction and brought to a full latch position. 
     The ratchet  14  has a claw part  14   a . The claw part  14   a  is formed so as to protrude towards the latch  12 , at a radial direction end portion of the ratchet  14 . The ratchet  14  is engageable with the half latch engagement portion  18  and the full latch engagement portion  19  of the latch  12  via that protruded portion when the ratchet  14  is rotated in the clockwise direction. The ratchet  14  is continuously biased in the clockwise direction by a spring elastic force. 
     When a door moves to be closed, the striker  15  fixed to a vehicle body relatively advances into an advancement passage  16  formed in the latch body  10 , engages with the engagement groove  17  of the latch  12 , and causes the latch  12  at an unlatch position to be rotated in the full latch direction (clockwise direction). When the latch  12  is brought to the half latch position, the ratchet  14  is rotated in the clockwise direction by the spring elastic force and the claw part  14   a  and the half latch engagement portion  18  of the latch  12  become engageable with each other. Further, when the latch  12  is brought to the full latch position, the claw part  14   a  and the full latch engagement portion  19  of the latch  12  become engageable with each other. When the claw part  14   a  of the ratchet  14  engages with the full latch engagement portion  19  of the latch  12 , the door closing operation is complete and the door is maintained in a closed-door state. 
       FIG. 2  illustrates a rear face of the latch unit. At an end portion of the latch shaft  11 , a latch switch lever  20  and an automatic closing lever  21  as illustrated in  FIG. 4  are installed. The latch switch lever  20  and the automatic closing lever  21  rotate integrally and in association with the latch  12 , and in this embodiment, the latch switch lever  20  and the automatic closing lever  21  are coupled to each other by a coupling pin  22  penetrating through the Latch body  10  and associatively rotate about the latch shaft  11 . 
     A conventionally well known motor-type automatic closing mechanism  23  is associatively coupled to the automatic closing lever  21 . When the automatic closing lever  21  is rotated by a motor power of the automatic closing mechanism  23 , the latch  12  at the half latch position is rotated by the motor power to the full latch position. 
     At an end portion of the ratchet shaft  13 , a ratchet lever  24  that rotates in association with the ratchet  14  is provided. The ratchet lever  24  preferably is made of a metal plate, and is able to operate in association with the ratchet  14  by a part of the ratchet lever  24  being bent and engaged with the ratchet  14 . The ratchet lever  24  is associatively coupled to an open handle (not illustrated) of a door. When the ratchet lever  24  is rotated by a door opening operation of the open handle, the ratchet  14  is rotated in a door opening direction (anticlockwise direction in  FIG. 1 ) and is released from the engagement with the latch  12 . When the ratchet  14  is released from the engagement with the latch  12 , the door is brought into an openable state. 
     Further, a conventionally well known motor-type automatic releasing mechanism  25  is associatively coupled to the ratchet lever  24 . The ratchet  14  is able to be released from the engagement with the latch  12  to bring the door into the openable state, also by a motor power of the automatic releasing mechanism  25 . 
     As illustrated in  FIG. 3 , at a lower portion of the latch body  10  on a rear face side thereof (a ratchet side on a rear face of the latch body  10 ), a switch assembly  26  of a driven side switch group is provided. The switch assembly  26  includes a switch case  27 , and a ratchet switch  32  and latch switches (a half latch switch  33  and a full latch switch  34 ) that are installed in this switch case  27 . The switch case  27  is made of, for example, a synthetic resin. The switch case  27  is fixed to the latch body  10  by a fixing means  28 , such as a screw. Three switch accommodating portions  29 ,  30 , and  31  are integrally formed with the switch case  27 . The ratchet switch  32  is accommodated in the switch accommodating portion  29 , the half latch switch  33  is accommodated in the switch accommodating portion  30 , and the full latch switch  34  is accommodated in the switch accommodating portion  31 . The switches  32 ,  33 , and  34  are respectively accommodated in the switch accommodating portions  29 ,  30 , and  31  beforehand to be separately manufactured as the assembly  26 . The switch case  27  is fixed to the latch body  10  by the fixing means  28  with the switches  32 ,  33 , and  34  having been respectively installed in the switch accommodating portions  29 ,  30 , and  31 . 
     The ratchet switch  32  detects a position of the ratchet  14 . The latch switches detect positions of the latch  12 , the half latch switch  33  detecting the half latch position of the latch  12  and the full latch switch  34  detecting the full latch position of the latch  12 . 
     The half latch switch  33  and full latch switch  34  switch over from OFF to ON by coming into contact with a cam surface  35  (see  FIG. 2  and  FIG. 4 ) of the latch switch lever  20  that rotates in association with the latch  12 . The cam surface  35  is formed on an outer peripheral surface of the latch switch lever  20 . The positions of the latch  12  are detected by the cam surface  35  coming into contact with the latch switches  33  and  34  and the latch switches  33  and  34  switching over from OFF to ON, due to rotation of the latch switch lever  20 . Further, the ratchet switch  32  switches over from OFF to ON by coming into contact with a ratchet switch lever  36  of  FIG. 4  (see  FIG. 4 ) that integrally rotates with the ratchet lever  24 . The ratchet switch lever  36  is provided, together with the ratchet lever  24 , at the end portion of the ratchet shaft  13 . A position of the ratchet  14  is detected by the ratchet switch lever  36  coming into contact with the ratchet switch  32  and the ratchet switch  32  being switched over from OFF to ON. The switch case  27  is arranged substantially below a rear face side bulged portion  37  of the latch body  10 , the rear face side bulged portion  37  zoning the advancement passage  16  in  FIG. 3 . 
     A driving mechanism of this embodiment has the automatic closing mechanism  23  and the automatic releasing mechanism  25 . This driving mechanism is driven by one common motor  38 , and a sector gear  39  rotates normally (automatic closing rotation) from a neutral position by normal rotation of the motor  38  and the sector gear  39  rotates reversely (automatic releasing rotation) from the neutral position by reverse rotation of the motor  38 . These configurations themselves are able to be substituted with conventional configurations and thus description of details of the configurations will be omitted. The driving mechanism of this embodiment has, as illustrated in  FIG. 5 , the motor  38  and the sector gear  39 . The sector gear  39  is pivotally supported by a sector shaft  50 . The sector gear  39  has a sector form and on a peripheral surface thereof, teeth  39   a  are formed. An output gear of the motor  38  is engaged with the teeth  39   a  of the sector gear  39 , and by the motor  38  being driven, the sector gear  39  is rotated about the sector shaft  50 . The sector gear  39  is configured to rotate the automatic closing lever  21  such that the latch  12  is rotated in the full latch direction when the sector gear  39  rotates (normally rotates) in one direction (clockwise direction in  FIG. 5 ) from the neutral position and to rotate the ratchet lever  24  such that the ratchet  14  is rotated in a direction in which the ratchet  14  is released from the engagement with the latch  12  when the sector gear  39  rotates (reversely rotates) in the other direction (anticlockwise direction in  FIG. 5 ) from the neutral position. In the driving mechanism configured as described above, when the sector gear  39  normally rotates from the neutral position by a power of the motor  38 , the automatic closing lever  21  of  FIG. 2  is rotated, the latch  12  is rotated in the full latch direction, the full latch engagement portion  19  of the latch  12  and the claw part  14   a  of the ratchet  14  engage with each other, and a closed-door state is achieved. Further, when the sector gear  39  reversely rotates from the neutral position, the ratchet lever  24  of  FIG. 2  is rotated, the ratchet  14  separates from the latch  12 , and the openable state is achieved. 
     In this embodiment, two types of neutral position of the sector gear  39  are present, which are a neutral position in an open-door state and a neutral position in a closed-door state, in relation with a gear interlocking cam body  40  that turns a driving side switch group ON or OFF, the gear interlocking cam body  40  being the gist of the present application. 
     The gear interlocking cam body  40  as illustrated in  FIG. 8  is attached to the sector gear  39  of this embodiment. The gear interlocking cam body  40  rotates about the sector shaft  50  integrally with the sector gear  39 . On a peripheral surface of the gear interlocking cam body  40 , a first cam surface  47  and a second cam surface  48  are formed along a circumferential direction of the gear interlocking cam body  40 . The first cam surface  47  is configured to have a right side surface  47   a  that is flat and a left side surface  47   b  that is adjacent to this right side surface  47   a  and that is flat. The first cam surface  47  is configured to be mountain-shaped when viewed from the front with the right side surface  47   a  and the left side surface  47   b , and an apex thereof is formed to be obtuse-angled. The second cam surface  48  is linked to and starts from an end of the first cam surface  47 . Specifically, the second cam surface  48  extends from a left end of the left side surface  47   b  of the first cam surface  47  towards the left in  FIG. 5 . The second cam surface  48  is configured to have a curved surface. This curved surface has an arc shape centering around the sector shaft  50  when viewed from the front. 
     In the vicinity of the gear interlocking cam body  40 , as illustrated in  FIG. 6 , a switch assembly  41  that is the driving side switch group is provided. The switch assembly  41  includes a switch case  42  (not illustrated in  FIG. 6  but see  FIG. 7 ) and a neutral switch  45  and a gear detection switch  46 , which are installed in this switch case  42 . The switch case  42  is made of, for example, a synthetic resin. The switch case  42  ( FIG. 7 ) is fixed to a base plate or the like (not illustrated) of the driving mechanism by a fixing means, such as a screw. Two switch accommodating portions  43  and  44  are integrally formed with the switch case  42 . The neutral switch  45  is accommodated in the switch accommodating portion  43  and the gear detection switch  46  is accommodated in the switch accommodating portion  44 , to be separately manufactured as the switch assembly  41 . 
     The neutral switch  45  is configured to be turned ON by coming into contact with the mountain-shaped first cam surface  47  of the gear interlocking cam body  40 . The neutral switch  45  is kept in the ON state by being in contact with the right side surface  47   a  of the first cam surface  47  as illustrated in  FIG. 6  in an initial state of the open-door state (see, simultaneously,  FIG. 9 ). This state is the neutral position of the sector gear  39  in the open-door state. When the door closing operation is started from the state of  FIG. 6  by the activation of the automatic closing mechanism  23 , the sector gear  39  is rotated in the clockwise direction in  FIG. 5 , the neutral switch  45  is kept in the ON state until the neutral switch  45  goes over the apex of the first cam surface  47  and is released from a contact with the left side surface  47   b  of the first cam surface  47 , and the neutral switch  45  is switched OFF when the neutral switch  45  is released from a contact with the left side surface  47   b . The switch assembly  41  of this embodiment is configured such that the second cam surface  48  does not come into contact with the neutral switch  45 . 
     The gear detection switch  46  is configured to be turned ON by coming into contact with the second cam surface  48 , which is a continuous single arc surface of the gear interlocking cam body  40 . The gear detection switch  46  is in contact with a left end portion of the second cam surface  48  as illustrated in  FIG. 6  and is kept in the ON state in the initial state of the open-door state (see  FIG. 9 ). When the door closing operation is started from the state of  FIG. 6  by the activation of the automatic closing mechanism  23 , the sector gear  39  is rotated in the clockwise direction in  FIG. 5  and the gear detection switch  46  is immediately switched OFF by being released from the contact with the second cam surface  48 . That is, in this embodiment, after the start of the door closing operation by the activation of the automatic closing mechanism  23 , a duration of the ON state of the gear detection switch  46  is caused to be shorter than a sustaining time period of the ON state of the neutral switch  45 . The neutral switch  45  and the gear detection switch  46  are both switched over from ON to OFF after the start of the door closing operation by the activation of the automatic closing mechanism  23 , but at this stage, control based on this signal switch-over is not performed. However, the immediate switch-over of the gear detection switch  46  from ON to OFF because of the gear detection switch  46  having been positioned at the left end portion of the second cam surface  48  is an important matter related to the gist of the present application, as described later. 
     The closing operation by the activation of the automatic closing mechanism  23  will now be described. By a door moving in a door closing direction, the striker  15  comes into contact with the latch  12  to rotate the latch  12  in the full latch direction. When the half latch engagement portion  18  of the latch  12  passes the claw part  14   a  of the ratchet  14 , the ratchet  14  is rotated in the clockwise direction in  FIG. 1  by the spring elastic force. By the rotation of the ratchet  14  in the clockwise direction, the ratchet switch  32  comes into contact with the ratchet switch lever  36  to be turned ON, and a half latch state is detected system-wise. When the ratchet switch  32  is turned ON, the automatic closing mechanism  23  is activated and the door closing operation is started. When the door closing operation is started by the activation of the automatic closing mechanism  23 , the sector gear  39  is rotated in the clockwise direction in  FIG. 5  by a power of the motor  38 . When the sector gear  39  is rotated in the clockwise direction, first, the second cam surface  48  is released from the contact with the gear detection switch  46  and the gear detection switch  46  is turned OFF, and subsequently, the first cam surface  47  is released from the contact with the neutral switch  45  and the neutral switch  45  is turned OFF (the gear detection switch  46  does not contact with the second cam surface  48  that is depressed). 
     After the half latch state is detected, by the operation of the automatic closing mechanism  23  being continued, the latch  12  is rotated in the full latch direction, the cam surface  35  of the latch switch lever  20  comes into contact with the half latch switch  33  to turn the half latch switch  33  ON, and subsequently, the full latch switch  34  is turned ON by coming into contact with the cam surface  35 . After the half latch switch  33  is turned ON and before the full latch switch  34  is switched ON, the ratchet  14  is pushed back in the door opening direction (anticlockwise direction in  FIG. 1 ) against the spring elastic force by the contact with a side surface (peripheral surface) of the latch  12 . By this rotation of the ratchet  14  in the anticlockwise direction, the ratchet switch  32  is released from the contact with the ratchet switch lever  36  and turned OFF. When the full latch engagement portion  19  of the latch  12  passes the claw part  14   a  of the ratchet  14 , the ratchet  14  is rotated in the clockwise direction in  FIG. 1  by the spring elastic force again. By this rotation of the ratchet  14  in the clockwise direction, the ratchet switch  32  comes into contact with the ratchet switch lever  36  to be turned ON, and a full latch state is detected system-wise. 
     When the full latch state is detected, after some time lag for safety, the motor  38  is rotated reversely and the automatic closing mechanism  23  (sector gear  39 ) returns to neutral. This return to neutral is detected by the sector gear  39  being rotated in the anticlockwise direction in  FIG. 5  by the reverse rotation of the motor  38  and the neutral switch  45  coming into contact with the left side surface  47   b  of the first cam surface  47  to be switched ON from OFF. The operation of the automatic closing mechanism  23  is ended by this return of the sector gear  39  to neutral. The state of  FIG. 6  illustrates the neutral position of the sector gear  39  in the open-door state and the neutral switch  45  therein is ON by being in contact with the right side surface  47   a  of the first cam surface  47 . After the door has been closed, the neutral switch  45  is turned ON by coming into contact with the left side surface  47   b  of the first cam surface  47 . Such a state where the neutral switch  45  has been turned ON by the contact with the left side surface  47   b  of the first cam surface  47  is the neutral position in the closed-door state. In this state, the gear detection switch  46  is not in contact with the second cam surface  48 . Accordingly, as illustrated in  FIG. 9 , the OFF-state of the gear detection switch  46  is continued even after the operation of the automatic closing mechanism  23  is ended. 
     The gear detection switch  46  is turned ON after the sector gear  39  is reversely rotated by the automatic releasing mechanism  25  (after the automatic releasing function is operated). After the automatic releasing function is operated and until the automatic closing function is operated, the ON state of the gear detection switch  46  is continued. Thus, in the closed-door state that is used overwhelmingly longer than the open-door state, the gear detection switch  46  is maintained in the OFF state. 
     Since, according to the above description of this embodiment, the operation of the automatic closing mechanism  23  is configured to be initiated from the switch-over of the ratchet switch  32  from OFF to ON, a timing to start the operation of the automatic closing mechanism  23  is clarified. 
     Further, when the automatic closing mechanism  23  is operated to close the door, the neutral switch  45  separates from the mountain-shaped first cam surface  47  of the gear interlocking cam body  40  to be switched over from ON to OFF, the gear detection switch  46  positioned at the left end portion of the second cam surface  48  is immediately released from the contact with the second cam surface  48  after the activation of the automatic closing mechanism  23  to be switched over from ON to OFF, and thus, particularly, a duration of the ON state of the gear detection switch  46  is able to be set short and improvement of the durability is able to be expected. 
     Further, since the gear detection switch  46  is configured to be turned ON by coming into contact with the second cam surface  48  for detecting the automatic releasing operation and is set to be turned ON only when the door is opened, an ON time period of the gear detection switch  46  is able to be set short and improvement of the durability is able to be expected, even further. 
     Further, since the second cam surface  48  that detects the automatic releasing operation with a rotation amount less than the rotation amount of the automatic closing operation is linked to the end of the left side surface  47   b  of the first cam surface  47 , the gear interlocking cam body  40  is able to be downsized. 
     According to the present invention, since operation of an automatic closing mechanism is configured to be initiated by switch-over of a ratchet switch from OFF to ON, a timing to start the operation of the automatic closing mechanism is clarified, and as a result, in a short time period after operating the automatic closing mechanism, a gear detection switch is able to be separated from a second cam surface to be switched over from ON to OFF, an ON time period of the gear detection switch is able to be set short, and improvement of the durability is able to be expected. 
     Further, since the second cam surface that does not come into contact with a neutral switch is linked to an end of a first cam surface, a gear interlocking cam body is able to be downsized. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.