Patent Publication Number: US-9903143-B2

Title: Switch assembly of vehicle door latch device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2014-178597 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 device, and in particular, to a switch assembly that detects positions of a latch and a ratchet of the latch device. 
     2. Description of the Related Art 
       FIG. 7  illustrates a front face of a conventionally well known vehicle door latch device (latch unit), and onto a latch body A of the latch device, the latch body A being formed of a synthetic resin or the like, a latch C is pivotally supported by a latch shaft B and a ratchet E is pivotally supported by a ratchet shaft D. When a door moves to be closed, a striker F fixed to the body of the vehicle relatively advances into an advancement passage G formed in the latch body A, engages with an engagement groove H of the latch C, and rotates the latch C at an unlatched position in a full latch direction (clockwise direction). When the latch C is brought to a half latch position, the ratchet E is rotated by a spring elastic force in the clockwise direction and becomes engageable with a half latch engagement portion J of the latch C; when the latch C comes to a full latch position, the ratchet E becomes engageable with a full latch engagement portion K of the latch C; and when the ratchet E engages with the full latch engagement portion K of the latch C, the door closure operation is complete and the door is maintained in a closed state. 
     Further, a conventional latch unit is sometimes provided with an automatic closer function for rotating the latch C at the half latch position towards the full latch position by a motor power and an automatic releasing function for rotating a ratchet E by a motor power in a door opening direction (anticlockwise direction in  FIG. 7 ) to separate the ratchet E from the full latch engagement portion K of the latch C and bring the door into an openable state (see, for example, Japanese Patent Application Laid-open No. 2014-009477). In this case, the latch unit is provided with a latch switch L that detects a position of the latch C and a ratchet switch M that detects a position of the ratchet E, and the automatic closer function and the automatic releasing function are controlled by signals from these switches being used. 
     In the latch unit illustrated in  FIG. 7 , the latch C (latch shaft B) and the ratchet E (ratchet shaft D) are respectively arranged separately, on a rear face side of the latch body A, to an upper side (latch side) and to a lower side (ratchet side) in the figure, of the advancement passage G of the striker (striker moving trajectory). With such an arrangement relation, an external force added from the striker F to the latch C is dispersed between and supported by the two shafts B and D above and below. In the industry, this arrangement structure is called “reaction force halving structure”, and this “reaction force halving structure” is the mainstream of the arrangement relation between a latch and a ratchet. 
     In a latch unit employing the “reaction force halving structure”, the latch switch L and the ratchet switch M are also respectively arranged separately to the latch side and the ratchet side divided by the advancement passage G, on the rear face side of the latch body A. Accordingly, two switch assemblies thus needing to be separately prepared and more than one step being required in the installation operation have been cost increasing factors. 
     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 switch assembly of a vehicle door latch device, the switch assembly including: a latch switch detecting a position of a latch, the latch being pivotally supported by a latch shaft to be engaged with a striker, the latch shaft being mounted on a latch body, the latch body including an advancement passage into which the striker relatively advances upon door closure; a ratchet switch that detecting a position of a ratchet, the ratchet being pivotally supported by a ratchet shaft to be engaged with the latch and prevented reverse rotation of the latch, the ratchet shaft being mounted on the latch body; and a one common switch case that the latch switch and the ratchet switch are installed in the one common switch case, wherein the latch and the ratchet are arranged on a front face side of the latch body, the latch shaft and the ratchet shaft are arranged to be isolated across a striker moving trajectory of the striker, and the common switch case is arranged on the latch body on one side of the striker moving trajectory. 
     The switch assembly according to another aspect of the present invention may include a latch switch lever that rotates in association with the latch and includes a cam surface that comes into contact with a movable terminal of the latch switch. The latch switch lever is arranged on the rear face of the latch body, and the movable terminal and the cam surface are configured to come into contact with each other at a position where the movable terminal and the cam surface overlap with a back face side bulged portion of the latch body, the back face side bulged portion zoning the advancement passage. 
     The switch case according to still another aspect of the present invention may be configured to not overlap with the back face side bulged portion of the latch body, the back face side bulged portion zoning the advancement passage. 
     The switch case according to further another aspect of the present invention may be configured to not overlap with the back face side bulged portion. 
     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 switch assembly, 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 schematic diagram illustrating an arrangement position of a switch case with respect to a latch body of the latch unit; 
         FIG. 4  is a schematic diagram illustrating a state where three switches have been installed in the switch case of  FIG. 3 ; 
         FIG. 5  is an enlarged perspective view of the switch case; 
         FIG. 6  is an exploded view of a rear face side of the latch unit; and 
         FIG. 7  is a schematic diagram of a conventional vehicle door latch device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will be described. The gist of the present invention is in a switch assembly including a latch switch and a ratchet switch. A configuration of a latch unit itself may be the same as the conventional one. As illustrated in  FIG. 1 , onto a latch body  10  of the latch unit (latch device), the latch body  10  being formed of a synthetic resin 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 unlatched 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 state. 
     The above described latch unit includes, similarly to the conventional example illustrated in  FIG. 7 , an arrangement structure called “reaction force halving structure”. The latch  12  (latch shaft  11 ) and the ratchet  14  (ratchet shaft  13 ) face each other across the advancement passage  16  of the striker  15  and are respectively arranged separately to an upper side (latch side) and a lower side (ratchet side) that are divided by the advancement passage  16  in  FIG. 1 . The advancement passage  16  according to this embodiment is zoned by a rear face side bulged portion  37  as illustrated in  FIG. 3  and  FIG. 4 . The rear face side bulged portion  37  is configured as a portion bulged to a rear face side in the latch body  10 . If a left-right direction on the plane of paper in  FIG. 3  and  FIG. 4  corresponds to a front-back direction of the latch body  10 , the rear face side bulged portion  37  extends in the front-back direction of the latch body  10 . 
       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. 6  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 electrically rotated 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 . The above configuration is similar to that of a conventional latch unit. 
     A switch assembly of this embodiment will be described. A switch assembly  26  illustrated in  FIG. 4  includes a switch case  27  (see  FIG. 3 ,  FIG. 5 , and  FIG. 6 ), 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, and 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 switch case  27  is formed such that when the switch case  27  is fixed to the latch body  10 , the ratchet switch  32  accommodated in the switch accommodating portion  29  is opposite to the ratchet shaft  13 . Further, the switch case  27  is formed such that when the switch case  27  is fixed to the latch body  10 , the switches  33  and  34  respectively accommodated in the switch accommodating portion  30  and switch accommodating portion  31  are opposite to the latch shaft  11  and are arranged along a rotation direction of the latch shaft  11 . 
     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  respectively have movable terminals  38  and  39 . 
     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. 6 ) 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 movable terminal  38  and  39  of 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  (see  FIG. 6 ) 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  installed with the respective switches  32 ,  33 , and  34  is arranged on a rear face of the latch body  10  on the ratchet side of a striker moving trajectory, as illustrated in  FIG. 4 . More preferably, the switch case  27  is arranged such that the switch case  27  does not overlap in the front-back direction with the rear face side bulged portion  37  of the latch body  10 , the rear face side bulged portion  37  zoning the advancement passage  16 . Accordingly, the switch case  27  is preferably arranged to come into contact with a lower face (face on the ratchet side) of the rear face side bulged portion  37 . As a result, the size of the whole latch device with the switch case  27  being arranged in the latch device is able to be made compact. Further, the movable terminals  38  and  39  at distal ends of the half latch switch  33  that detects a half latch state (half latch position) of the latch  12  and the full latch switch  34  that detects a full latch state (full latch position) of the latch  12  are preferably arranged such that only the movable terminals  38  and  39  overlap in the front-back direction with the rear face side bulged portion  37  and contact with the cam surface  35  of the latch switch lever  20  at a position where the movable terminals  38  and  39  overlap with the rear face side bulged portion  37 . That is, the switch assembly  26  preferably has the following configurations: a configuration in which a moving trajectory of the cam surface  35  illustrated by a virtual line  35   a  (arc-shaped curve) overlaps with the rear face side bulged portion  37  when the latch switch lever  20  rotates about the latch shaft  11 ; a configuration in which the latch switches  33  and  34  and the switch case  27  are arranged such that the movable terminals  38  and  39  of the latch switches  33  and  34  protrude from the switch case  27  and the protruded movable terminals  38  and  39  overlap with the rear face side bulged portion  37 ; and a configuration in which the movable terminals  38  and  39  of the latch switches  33  and  34  are arranged on the moving trajectory of the cam surface  35  illustrated by the virtual line  35   a , such that the movable terminals  38  and  39  of the latch switches  33  and  34  arranged at the position where the movable terminals  38  and  39  overlap with the rear face side bulged portion  37  come into contact with the cam surface  35  of the latch switch lever  20 . 
     As described above, since the switch assembly  26  according to this embodiment employs the concept of arranging the switch assembly  26  on only one side (ratchet side) of the striker moving trajectory, the ratchet switch  32 , half latch switch  33 , and full latch switch  34  are able to be manufactured by being installed in the one common switch case  27  beforehand, and thus the cost for the installation operation in the latch body  10  is able to reduced and suppression of the manufacturing cost is able to be expected. 
     Further, by causing the movable terminals  38  and  39  of the half latch switch  33  and full latch switch  34  to come into contact, at the position where the movable terminals  38  and  39  overlap with the rear face side bulged portion  37 , with the cam surface  35  of the latch switch lever  20 , a space (the switch accommodating portion  30  and switch accommodating portion  31 ) for installing the half latch switch  33  and full latch switch  34  is able to be rationally secured in the switch case  27  and the concept of arranging the switch assembly  26  only on the ratchet side of the striker moving trajectory is able to be implemented well. 
     The above described switch case  27  may be arranged on the latch side of the striker moving trajectory, instead of being configured to be arranged on the ratchet side of the striker moving trajectory. 
     According to the present invention, since a concept of arranging a switch assembly on only a ratchet side of a striker moving trajectory is employed, a ratchet switch, a half latch switch, and a full latch switch are able to be manufactured by being installed in one common switch case beforehand, workload for the installation in a latch body is able to reduced, and thus suppression of the manufacturing cost is able to be expected. 
     Further, by causing movable terminals of the half latch switch and full latch switch to come into contact, at a position where the movable terminals overlap with a rear face side bulged portion, with a cam surface of a latch switch lever, a space for installing the half latch switch and full latch switch is able to be rationally secured in the switch case and the concept of arranging the switch assembly on only one side (ratchet side) of the striker moving trajectory is able to be implemented smoothly. 
     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.