Abstract:
An actuating assembly for an automotive door latch device comprises a housing that operatively installs therein basic elements that are commonly used in an override function unit and a child proof function unit. The override function unit has a function wherein a manipulation of an inside door handle induces cancellation of the engaged condition of the latch means irrespective of the condition of the locking/unlocking means. The child proof function unit has a function wherein the manipulation of the inside door handle is made inoperative irrespective of the condition of the locking/unlocking means, thereby to make the cancellation of the engaged condition of the latch means impossible. The actuating assembly further comprises a cover that is coupled to the housing and holds thereon a selected element that is exclusively used in either one of the override function unit and the child proof function unit.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates in general to automotive door latch devices, and more particularly to automotive door latch devices of a type that comprises a striker that is fixed to a vehicle body, a latch assembly that is mounted to a door and includes a latch means that is engageable with the striker and a locking/unlocking means that causes the latch means to switch between an unlocked condition wherein an engaged condition of the latch means is unlocked and a locked condition wherein the engaged condition of the latch means is locked, and an actuating assembly that is connected to the latch assembly to actuate the latch means and the locking/unlocking means.  
         [0003]     2. Description of the Related Art  
         [0004]     Hitherto, various types of automotive door latch devices have been proposed and put into practical use particularly in the field of wheeled motor vehicles.  
         [0005]     Japanese Laid-open Patent Application (Tokkai) 2002-339625 shows a door latch device of override type in which upon manipulation of an inside door handle, the engagement between a latch plate and a striker is cancelled irrespective of the position of the latch plate. Japanese Laid-open Patent Application (Tokkai) 2002-81246 shows a door latch device of normal type that has not the above-mentioned override function, and Japanese Laid-open Patent Application (Tokkai) 2002-81247 shows a door latch device of child proof type in which manipulation of the inside door handle is inoperative irrespective of the position of the latch plate, thereby making cancellation of a locked condition of the latch plate impossible.  
       SUMMARY OF THE INVENTION  
       [0006]     In the above-mentioned known door latch devices, there are employed various basic elements that are commonly used in the different types of door latch devices, which are for example a knob lever that is linked to a lock knob mounted on an inside surface of a door, an inside lever that is connected to an operation handle mounted on the inside portion of the door, a transmission member that transmits the movement of the knob lever to the lock plate. Besides the above-mentioned basis elements, each type of the door latch devices employs a selected element that is exclusively used in each type, which is for example an override lever in case of the override type door latch device, and a child proof lever in case of the child proof type door latch device.  
         [0007]     However, in the above-mentioned known door latch devices, common usage of the basic elements and effective arrangement of the selected elements have been hitherto given little thought, which has induced increase in cost of the door latch devices.  
         [0008]     Accordingly, an object of the present invention is to provide an automotive door latch device that is constructed to make common usage of the latch assembly and effective arrangement of selected elements possible in both the override type and the child proof type.  
         [0009]     In accordance with the present invention, there is provided an automotive door latch device which comprises a striker fixed to a body of the vehicle; a latch assembly mounted to a door of the vehicle, the latch assembly including a latch means that is engageable with the striker and a locking/unlocking means that causes the latch means to switch between an unlocked condition wherein an engaged condition of the latch means is unlocked and a locked condition wherein the engaged condition of the latch means is locked; and an actuating assembly connected to the latch assembly to actuate the latch means and the locking/unlocking means, wherein the actuating assembly comprises a housing that operatively installs therein basic elements that are commonly used in an override function unit and a child proof function unit, the override function unit having a function wherein a manipulation of an inside door handle induces cancellation of the engaged condition of the latch means irrespective of the condition of the locking/unlocking means, the child proof function unit having a function wherein the manipulation of the inside door handle is made inoperative irrespective of the condition of the locking/unlocking means, thereby to make the cancellation of the engaged condition of the latch means impossible; and a cover that is coupled to the housing and holds thereon a selected element that is exclusively used in either one of the override function unit and the child proof function unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which:  
         [0011]      FIG. 1  is an exploded view of an override type door latch device which is a first embodiment of the present invention;  
         [0012]      FIG. 2  is a perspective view of the door latch device of the first embodiment;  
         [0013]      FIG. 3  is a front view of the door latch device of the first embodiment;  
         [0014]      FIG. 4  is a rear view of the door latch device of the first embodiment;  
         [0015]      FIG. 5  is a right side view of the door latch device of the first embodiment, that is taken from the direction of the arrow “V” of  FIG. 3 ;  
         [0016]      FIG. 6  is a left side view of the door latch device of the first embodiment, that is taken from the direction of the arrow “VI” of  FIG. 3 ;  
         [0017]      FIG. 7  is a left side view of the door latch device of the first embodiment with a cover removed;  
         [0018]      FIG. 8  is a left side view of an actuating assembly with a cover removed;  
         [0019]      FIG. 9  is an inside view of the cover;  
         [0020]      FIG. 10  is a left side view of an essential portion of the actuating assembly in an unlocked condition;  
         [0021]      FIG. 11  is a view similar to  FIG. 10 , but showing the essential portion in a locked condition;  
         [0022]      FIG. 12  is an exploded view of the essential portion;  
         [0023]      FIG. 13  is a left side view of a housing;  
         [0024]      FIG. 14  is a left side view of an essential portion of the housing;  
         [0025]      FIG. 15  is a vertically sectional view taken along the line “A-A” of  FIG. 6 ;  
         [0026]      FIG. 16  is a horizontally sectional view taken along the line “B-B” of  FIG. 6 ;  
         [0027]      FIG. 17  is a vertically sectional view taken along the line “C-C” of  FIG. 7 ;  
         [0028]      FIG. 18  is a horizontally sectional view taken along the line D-D” of  FIG. 7 ;  
         [0029]      FIG. 19  is an inside view of a latch unit;  
         [0030]      FIG. 20  is a front view of the latch unit in a locked condition;  
         [0031]      FIG. 21  is view similar to  FIG. 20 , but showing the latch unit in an unlocked condition;  
         [0032]      FIG. 22  is an enlarged view of a portion indicated by the arrow “E” in  FIG. 19 ;  
         [0033]      FIG. 23  is a view similar to  FIG. 22 , but showing a condition wherein a locking plate is in the middle of operation;  
         [0034]      FIG. 24  is a view similar to  FIG. 22 , but showing a condition wherein the locking plate is in an unlocking position;  
         [0035]      FIG. 25  is an exploded view of an essential portion of a child proof type door latch device which is a second embodiment of the present invention;  
         [0036]      FIG. 26  is a right side view of a cover that is used in the child proof type door latch device;  
         [0037]      FIG. 27  is a left side view of an actuating assembly of the child proof type door latch device, with the cover removed; and  
         [0038]      FIG. 28  is a left side view of an essential portion of the actuating assembly of the child proof type door latch device. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0039]     In the following, first and second embodiments  100  and  200  of the present invention will be described in detail with reference to the accompanying drawings, in which the first embodiment  100  is an override type door latch device and the second embodiment  200  is a child proof type door latch device.  
         [0040]     For ease of understanding, various directional terms, such as, right, left, upper, lower, rightward and the like are used in the following description. However, such terms are to be understood with respect to only a drawing or drawings on which a corresponding part or portion is shown. Throughout the specification, substantially same parts are denoted by the same numerals.  
         [0041]     Referring to FIGS.  1  to  24  of the drawings, there is shown an override type automotive door latch device  100  which is a first embodiment of the present invention.  
         [0042]     The door latch device  100  is of a type mounted on a left-front door of an associated motor vehicle. More specifically, the door latch device  100  is mounted on a rear (or free) end portion of the left-front door of which front end is hinged to a vehicle body.  
         [0043]     As is seen from  FIG. 2 , the door latch device  100  generally comprises a striker “ST” that is secured to a vehicle body (not shown), a latch assembly  102  that is secured by bolts or the like to the rear part of an associated door and an actuating assembly  103  that actuates the latch assembly  102 .  
         [0044]     The latch assembly  102  is of a commonly applicable type, and comprises as is seen from  FIG. 19 , a plastic case  4 , a latch unit  5  installed in the case  4  and engageable with the striker “ST” upon closing of the door. It is to be noted that for showing the interior of the case  4 , a cover plate  16  (see  FIG. 1 ) that covers an open side of the case  4  is not shown in  FIG. 19 .  
         [0045]     As is seen from  FIG. 19 , the latch unit  5  comprises a latch plate  7  that is pivotally installed in the case  4  through a pivot shaft  6  and engageable with the striker “ST” through an engaging recess  7   a  thereof, and a locking plate  9  that is pivotally installed in the case  4  through a pivot shaft  8  and engageable with pawl portions  7   b  and  7   c  formed on the latch plate  7 . Upon engagement with the pawl portions  7   b  and  7   c , pivoting of the latch plate  7  in an open direction, that is, in a counterclockwise direction in  FIG. 19  is suppressed. The latch plate  7  is biased to turn in a counterclockwise direction in  FIG. 19  by a coil spring  12  (see  FIG. 1 ) that is disposed about the pivot shaft  6 .  
         [0046]     When the door is kept closed, the latch plate  7  is in a close position as shown in  FIG. 19  wherein the striker “ST” is caught by the engaging recess  7   a  of the latch plate  7 . While, when the door is kept opened, the latch plate  7  is in an open position that is away from the close position by about 90 degrees in angle in a counterclockwise direction thereby releasing the striker “ST”. Upon closing of the door, the striker “ST” is led into the engaging recess  7   a  of the latch plate  7  turning the latch plate  7  to the close position and finally the latch plate  7  is locked at the close position by the locking plate  9 , as will be clarified from the following.  
         [0047]     During turning of the latch plate  7  from the open position to the close position, the locking plate  9  is turned counterclockwise from the position (viz., close position) of  FIG. 19  at first against a force of a biasing spring  13  and thereafter, that is, when the latch plate  7  is sufficiently turned toward the close position, the locking plate  9  is turned back in a clockwise direction due to the force of the biasing spring  13  and brought into engagement with one of the two pawl portions  7   b  and  7   c  of the latch plate  7 . Upon this, the turning of the latch plate  7  toward the open position is suppressed. That is, when the locking plate  9  is in engagement with the pawl portion  7   b , as shown in  FIG. 19 , the latch plate  7  is fully locked by the locking plate  9  thereby assuming a full-locked position, and when the locking plate  9  is in engagement with the other pawl portion  7   c , the latch plate  7  is half or incompletely locked by the locking plate  9  thereby assuming a half-locked position.  
         [0048]     When, due to manipulation of an outside door handle (not shown) mounted on an outside surface of the door, an after-mentioned open lever  11  is pivoted to its unlocking position, the locking plate  9  is turned counterclockwise in  FIG. 19  separating from the pawl portion  7   b  or  7   c  thereby releasing the latch plate  7 . With this, the latch plate  7  is permitted to release the striker “ST”, and thus permit opening the door when the door is pulled outward with a certain force.  
         [0049]     As is seen from  FIG. 19 , near the locking plate  9 , there is located a stopper  14  of rubber that is fixed to the case  4  for stopping excessive pivoting of the locking plate  9 .  
         [0050]     As is seen from FIGS.  22  to  24 , the stopper  14  is generally in a cubic shape and comprises a base portion  14   a  that is press-fitted in a generally U-shaped catch portion  4   a  provided by the case  4 . The base portion  14   a  is formed with a corrugated upper surface  14   c  against which a right arm portion of the locking plate  9  is able to abut.  
         [0051]     As is seen from  FIG. 23 , the stopper  14  is integrally formed with a lip portion  14   b  that extends obliquely upward from a left wall of the base portion  14   a . As is seen from this drawing, the lip portion  14   b  has a hammer like head portion  14   d  and at a middle portion thereof a downward projection  14   e.    
         [0052]     That is, when, upon movement of the latch plate  7  from the open position to the close position, the locking plate  9  is turned from the unlocking position (viz., the position shown in  FIG. 24 ) the locking position due to the force of the biasing spring  13 , a lower surface  9   a  of the right arm portion of the locking plate  9  is brought into abutment with an upper part of the hammer like head portion  14   d , and thus, the lip portion  14   b  is elastically bent downward having the downward projection  14   e  held by a supporting portion  4   b  provided by the case  4 . When, thereafter, the lip portion  14   b  is bent by a predetermined degree, the head portion  14   d  and the downward projection  14   e  are elastically compressed against the supporting portion  4   b . With this, as is seen from  FIG. 22 , the locking plate  9  is stopped at its locking position having the lower surface  9   a  thereof pressed against both the corrugated upper surface  14   c  of the base portion  14   a  and the hammer like head portion  14   d  of the lip portion  14   b  that is kept biased upward. That is, undesired shock that would be produced when the right arm portion of the locking plate  9  is brought into contact with the stopper  14  is softly absorbed or damped by the lip portion  14   b.    
         [0053]      FIGS. 20 and 21  show a front view of the latch assembly  102 . As will be understood from these drawings and  FIG. 1 , to a front surface side of the case  4 , there is secured a metallic base plate  15 .  
         [0054]     As is seen from  FIG. 20 , to the metallic base plate  15 , there is pivotally connected the open lever  11  through the pivot shaft  8 , and thus the open lever  11  and the locking plate  9  are pivotal together like a single unit. Furthermore, to the metallic base plate  15 , there are mounted a locking/unlocking lever  17  that is pivotally connected thereto through its shaft portion  17   a  and constitutes part of a locking/unlocking means, an outside lever  19  that is pivotally connected thereto through a shaft  18  and linked to an outside door handle (not shown), and a sub-lever unit  20  that is arranged between the locking/unlocking lever  17  and the outside lever  19  and constitute the other part of the locking/unlocking means.  
         [0055]     The locking/unlocking lever  17  is actuated by a lock knob (not shown) mounted on an inside surface of the door, an after-mentioned electric motor  33  installed in the actuating assembly  103  and/or a key cylinder (not shown) arranged on an outside surface of the door. That is, upon actuation, the locking/unlocking lever  17  is forced to pivot about the axis of the shaft portion  17   a  between a locking position as shown in  FIG. 20  and an unlocking position as shown in  FIG. 21 . As will be understood when comparing these two drawings, viz.,  FIGS. 20 and 21 , the unlocking position of  FIG. 21  is an angular position away from the locking position of  FIG. 20  by a predetermined angle in a counterclockwise direction. Due to a force of a coil spring  25  (see  FIG. 1 ) arranged between the locking/unlocking lever  17  and the base plate  15 , the locking/unlocking lever  17  can be pivoted to the locking or unlocking position in a snap action manner and held in such position.  
         [0056]     As is seen from  FIG. 20 , the locking/unlocking lever  17  is formed with a projection  17   b  that projects in this side in the drawing. As will be described in detail hereinafter, once the actuating assembly  103  is properly mounted to the latch assembly  102 , the projection  17   b  is brought into engagement with an after-mentioned transmission lever  46  of the actuating assembly  103  to achieve a synchronous movement therebetween.  
         [0057]     As is seen from  FIG. 1 , the sub-lever unit  20  comprises a first lever member  21  and a second lever member  22  which are separate members. As is seen from  FIG. 20 , the first lever member  21  has a lower end that is pivotally connected through a connecting shaft  21   a  to a free end portion of the outside lever  19 , and has an upper end that has a bent slot  21   b  slidably engaged with a projection  17   c  provided on a lower end portion of the locking/unlocking lever  17 . The second lever member  22  has a lower end portion that is pivotally connected through the connecting shaft  21   a  to the lower end of the first lever member  21 . Due to a force of a coil spring  23  arranged between the first and second lever members  21  and  22 , the second lever member  22  is biased in a clockwise direction about the connecting shaft  21   a  in  FIGS. 20 and 21 . It is to be noted that as is seen from  FIGS. 20 and 21 , due to the biasing force of the coil spring  23 , the first and second lever members  21  and  22  can move together like a single unit keeping their relative positioning.  
         [0058]     When the locking/unlocking lever  17  is in the locking position, the sub-lever unit  20  (viz., first and second lever members  21  and  22 ) is in its locking position as shown in  FIG. 20 , while when the locking/unlocking lever  17  is pivoted from the locking position to the unlocking position, the sub-lever unit  20  is pivoted in a clockwise direction to its unlocking position about the connecting shaft  21   a.    
         [0059]     In the illustrated embodiment, the locking/unlocking means is constructed to have the locking/unlocking lever  17  and the sub-lever unit  20 . However, in the present invention, the locking/unlocking means is not limited to such construction. That is, for example, the sub-lever unit  20  may comprise first and second lever members  21  and  22  which are integral to each other.  
         [0060]     In the following, a basic operation of the door latch device  100  will be described with reference to the drawings.  
         [0061]     It is to be noted that the locking condition of the locking/unlocking means is a condition wherein the locking/unlocking lever  17  and the sub-lever unit  20  assume their locking positions, while, the unlocking condition of the locking/unlocking means is a condition wherein the locking/unlocking lever  17  and the sub-lever unit  20  assume their unlocking positions.  
         [0062]     For ease of understanding, the following description on the basing operation will be commenced with respect to a condition wherein the locking/unlocking means is in the unlocking condition.  
         [0063]     When now the outside door handle (not shown) is manipulated for the purpose of opening the associated door, the outside lever  19  (see  FIG. 20 ) is pivoted from its standby position of  FIG. 20  to an unlocking position of  FIG. 21  against a force of a biasing coil spring  24  thereby to move the sub-lever unit  20  downward. Upon this, a canceling portion  22   a  of the second lever member  22  is brought into contact with a first engaging portion  11   a  of the open lever  11  thereby to turn the open lever  11  toward its unlocking position. Upon this, the locking plate  9  is pivoted toward the unlocking position together with the open lever  11  against the force of the spring  13  thereby to be released from the pawl portion  7   b  (or  7   c ) of the latch plate  7 . With this, the latch unit  5  becomes free and thus, the door is permitted to open when the door is pulled outward with a certain force.  
         [0064]     While, when, as is seen from  FIG. 20 , the locking/unlocking means is kept in its locking condition, manipulation of the outside door handle for the purpose of opening the door does not permit opening of the door for the reason that will be described in the following.  
         [0065]     That is, when, due to the manipulation of the outside door handle, the sub-lever unit  20  is moved downward, the canceling portion  22   a  of the second lever member  22  strikes air against the first engaging portion  11   a , and thus, the locking plate  9  is not turned toward the unlocking position.  
         [0066]     In the following, the actuating assembly  103  will be described in detail with reference to the drawings.  
         [0067]     As is seen from FIGS.  2  to  6 , the actuating assembly  103  is mounted to the latch assembly  102  and is a commonly applicable type, and comprises a plastic housing  31  to which after-mentioned basic elements that are commonly used in the above-mentioned latch assembly  102  are mounted and a plastic cover  32  that is connected to the housing  31  and has after-mentioned selected elements mounted thereto.  
         [0068]     The basic elements are the elements that are employed in a normal type door latch device that is free of an override function and a child proof function. The basic elements are for example a knob lever  35  that is linked to the lock knob mounted on the inside surface of the door, an inside lever  45  that is linked to an inside door handle (not shown) and the transmission lever  46  that transmits the movement of the knob lever  35  to the locking/unlocking means of the latch assembly  102 .  
         [0069]     In the actuating assembly  103  for the door latch device  100  mounted on the left front door of the vehicle, a key lever  36  that is linked to the key cylinder mounted on the outside surface of the door is added as one of the basic elements. In the electric type that actuates the locking/unlocking means with an aid of an electric power, the electric motor  33 , a worm wheel  34 , a motor shaft  33   a , a worm  33   b  that constitutes part of a speed reduction mechanism and a rotary switch  47  that senses operation of the key cylinder are added as the basic elements. In the override type, an override lever  41  is added as one of the basic elements, that is able to cancel the engaged condition of the latch unit  5  in synchronization with an operation of the basic element based on a manipulation of the inside door handle.  
         [0070]     While, as will be described in detail hereinafter, in the child proof type that is the second embodiment  200  of the present invention, a child proof lever  70  is added as one of the basic elements, that makes the operation of the inside lever  45  (which is induced by the operation of the inside door handle) inoperative thereby to make cancellation of the engaged condition of the latch unit  5  inoperative.  
         [0071]     Referring back to the override type door latch device  100  of the first embodiment, the door latch device  100  is of a type that is to be mounted on a left-front door and has both an override function and electric power function. Thus, the key lever  36 , the electric motor  33 , the worm wheel  34  and the rotary switch  47  are added as the basic elements. While, the override lever  41  is added as the selected element.  
         [0072]     As is understood from  FIGS. 1, 2  and  3 , the plastic housing  31  is arranged generally perpendicular to a front surface of the latch assembly  102  and has a part containing recess  31   a  in which the above-mentioned basic elements are installed. As is seen from  FIGS. 1 and 3 , from a rear end of the part containing recess  31   a , there extends a cover portion  31   x  that faces the front surface of the latch assembly  102  and covers the locking/unlocking means.  
         [0073]     As is seen from  FIGS. 1 and 7 , the knob lever  35  is pivotally held by a shaft portion  31   f  formed in the part containing recess  31   a  of the housing  31 . The knob lever  35  is connected through a cable  37  (see  FIG. 6 ) to the lock knob (not shown) mounted on the inside surface of the door. That is, in accordance with an operation of the lock knob, the knob lever  35  is pivoted between a locking position (as shown in  FIGS. 7, 8  and  11 ) that corresponds to the locking condition of the locking/unlocking means and an unlocking position (as shown in  FIG. 10 ) that is positioned away from the locking position of  FIG. 11  by an angle of about 45 degrees in a counterclockwise direction.  
         [0074]     The transmission lever  46  is received in the part containing recess  31   a  of the housing  31  and vertically slidable between a locking position (as shown in  FIGS. 7, 8  and  11 ) that corresponds to the locking condition of the locking/unlocking means and an unlocking portion (as shown in  FIG. 10 ) that corresponds to the unlocking condition of the locking/unlocking means. As shown in  FIG. 10 , the transmission lever  46  is formed at its upper portion with an opening  46   f  into which the above-mentioned projection  17   b  of the locking/unlocking lever  17  is inserted to provide a pivotal connection therebetween. As shown in the same drawing, the transmission lever  46  is formed at its upper right side with teeth  46   a ,  46   b  and  46   c  which are meshed with teeth  34   a ,  34   b  and  34   c  formed on a hollow shaft portion of the worm wheel  34 . Furthermore, the transmission lever  46  is formed at its middle portion with an opening  46   d  into which an end portion  35   a  of the knob lever  35  is inserted to provide a pivotal connection therebetween.  
         [0075]     As is understood from the above description, in synchronization with the movement of the knob lever  35  to the locking or unlocking position that is induced by a locking/unlocking operation of the lock knob (not shown), the locking/unlocking means of the latch assembly  102  is switched via the transmission lever  46  to the locking condition or the unlocking condition.  
         [0076]     As is seen from  FIGS. 1, 6 ,  7  and  10 , the inside lever  45  is pivotally held by a shaft portion  31   g  provided in the part containing recess  31   a  of the plastic housing  31 . The inside lever  45  is connected through a cable  38  (see  FIG. 6 ) to the inside door handle (not shown) that is mounted on the inside surface of the door. That is, when the inside door handle is manipulated for the purpose of opening the door, the inside lever  45  is turned about the shaft portion  31   g  in a counterclockwise direction in  FIG. 7 .  
         [0077]     As is seen from  FIG. 7 , the electric motor  33  is neatly and tightly received in a motor receiving recess  31   e  provided in the part containing recess  31   a  of the housing  31 . Although not shown in the drawings, upon manipulation of a remote control switch and the like, the motor  33  is energized to run in a desired direction.  
         [0078]     The worm wheel  34  is received in a worm wheel receiving recess  31   d  formed near the motor receiving recess  31   e  and rotatably held by a shaft  43  provided in the worm wheel receiving recess  31   d . As has been mentioned hereinabove, the teeth  34   a ,  34   b  and  34   c  formed on the hollow shaft portion of the worm wheel  34  are meshed with the teeth  46   a ,  46   b  and  46   c  of the transmission lever  46 . Thus, when, upon rotation of the motor  33 , the worm wheel  34  is turned in a counterclockwise direction in  FIG. 7 , the transmission lever  46  is moved downward, and when the worm wheel  34  is turned in a clockwise direction, the transmission lever  46  is moved upward, resulting in that the locking/unlocking means is switched through the transmission lever  46  to the unlocking condition or the locking condition. When the transmission lever  46  is moved to the lower or upper predetermined position, a limit switch  48  stops the energization of the motor  33 . Upon this, the worm wheel  34  is returned to its neutral position due to the biasing force of a biasing coil spring  44  (see  FIGS. 1 and 18 ). The limit switch  48  is received in the part containing recess  31   a  of the housing  31 .  
         [0079]     As is seen from  FIGS. 1, 7 ,  12  and  17 , the key lever  36  pivotally received in a cylindrical key lever receiving bore  31   b  formed in the housing  31 . The key lever  36  has a shaft portion  36   a  that projects outward through a through bore  31   j  (see  FIG. 17 ) formed in an end portion of the key lever receiving bore  31   b . As is seen from  FIGS. 12 and 17 , to the projected end of the shaft portion  36   a , there is secured a connecting lever  36   f  that is connected to the key cylinder (not shown) mounted on the outer surface side of the door.  
         [0080]     As is seen from  FIG. 7 , the key lever  36  is formed therearound with teeth  36   b . As shown, one of the teeth  36   b  that is positioned at the uppermost part has a larger size, that is denoted by numeral  36   c . As will be described hereinafter, the teeth  36   b  and the larger tooth  36   c  are arranged to face the rotary switch  47 .  
         [0081]     As will be seen from  FIGS. 12 and 17 , between an outer surface of the shaft portion  36   a  of the key lever  36  and an inner surface of the key lever receiving bore  31   b , there is arranged an annular sealing member  49 . With this sealing member  49 , undesired phenomenon wherein rain water entering the interior of the door enters the part containing recess  31   a  through the key lever receiving bore  31   b  is suppressed.  
         [0082]     When, with the locking/unlocking means assuming the locking condition, the key cylinder is turned by a key (not shown) for the purpose of unlocking the door, the key lever  36  (see  FIGS. 7 and 8 ) is turned in a clockwise direction by a certain angle from its neutral position of the drawings, so that an upper pawl portion  36   d  (see  FIG. 10 ) formed on the key lever  36  is moved down and brought into contact with a projection  46   e  of the transmission lever  46 . With this, the transmission lever  46  is moved from the locking position to the unlocking position thereby to induce the unlocking condition of the locking/unlocking means. While, when, with the locking/unlocking means assuming the unlocking condition, the key cylinder is turned in a reversed direction by the key for the purpose of locking the door, the key lever  36  is turned in a counterclockwise direction by a certain angle from the neutral position as shown in  FIG. 10 , so that a lower pawl portion  36   e  formed on the key lever  36  is moved up and brought into contact with the projection  46   e  of the transmission lever  46 . With this, the transmission lever  46  is moved from the unlocking position to the locking position thereby to induce the locking condition of the locking/unlocking means.  
         [0083]     As is seen from  FIGS. 1, 7 ,  8  and  12 , the rotary switch  47  is snugly and tightly received in a switch receiving wall portion  31   c  positioned near the key lever receiving bore  31   b . As is best shown in  FIG. 12 , the rotary switch  47  is formed, at a part facing the teeth  36   b  of the key lever  36 , with teeth  47   a  that are meshed with the teeth  36   b  of the key lever  36 . As shown, in the toothed part of the rotary switch  47 , there is formed a larger notch  47   b  with which the above-mentioned larger tooth  36   c  of the key lever  36  is engaged. More specifically, the engagement between the larger notch  47   b  and the larger tooth  36   c  is established only when the rotary switch  47  and the key lever  36  take proper positions relative to each other upon assembly.  
         [0084]     As is seen from  FIGS. 1, 2 ,  5 ,  6 ,  7 ,  8 ,  13  and  15 , at a lower portion of the part containing recess  31   a  of the housing  31 , there are formed two tube fixing portions  60  and  61  that are used for fixing ends  39   a  and  40   a  of two tubes  39  and  40  (see  FIG. 6 ) through which the above-mentioned cables  37  and  38  pass.  
         [0085]     As is seen from  FIGS. 6 and 7 , particularly  FIG. 7 , the two tube fixing portions  60  and  61  spaced from each other by a given distance. As shown, at mutually facing wall portions of these two fixing portions  60  and  61 , there are provided respective first pawl portions  60   a  and  61   a  that project into respective groove portions  60   b  and  61   b  of the fixing portions  60  and  61 . These first pawl portions  60   a  and  61   a  are resiliently flexible. In the groove portions  60   b  and  61   b , there are formed respective second pawl portions  60   c  and  61   c  at positions facing the first pawl portions  60   a  and  61   a . The second pawl portions  60   c  and  61   c  are relatively rigid as compared with the first pawl portions  60   a  and  61   a.    
         [0086]     As is seen from  FIG. 7 , between the two fixing portions  60  and  61  of the housing  31 , there is formed a generally rectangular opening  31   h . As is seen from  FIG. 16 , the opening  31   h  is formed at its front end portion with an inclined lip portion  31   i  that projects toward the inside surface of the door.  
         [0087]     As is seen from  FIGS. 7, 8 ,  13 ,  14  and  17 , below the key lever receiving bore  31   b  of the housing  31 , there is defined a rain water guide passage  31   k  through which rain water is guided toward the cover portion  31   x  (see  FIG. 8 ) and discharged to the outside of the door latch device.  
         [0088]     Due to provision of the rain water guide passage  31   k , the various electric elements, such as the motor  33 , the rotary switch  47 , the limit switch  48  and the like, are protected from water (viz., rain water) that might enter the key lever receiving bore  31   b  from the through bore  31   j  irrespective of provision of the sealing member  49 .  
         [0089]     As is seen from  FIGS. 1, 8 ,  13 ,  14  and  18 , the cover portion  31   x  of the housing  31  is formed with three mating openings  31   q  with which three pawl portions  15   a  provided by the metallic base plate  15  are respectively engaged. That is, by properly engaging the pawl portions  15   a  with the mating openings  31   q , the housing  31  becomes fixed to a front side of the latch assembly  102 . It is to be noted that the uppermost one of the three mating openings  31   q , that is positioned near the key lever receiving bore  31   b , is communicated with the water guide passage  31   k  as is seen from  FIG. 8 . Accordingly, the water led to the water guide passage  31   k  is charged toward the cover portion  31   x  of the housing  31  from the uppermost mating opening  31   q.    
         [0090]     As is best seen from  FIG. 9 , the plastic cover  32  is formed at a peripheral portion thereof with a plurality of catching lugs  32   a . As is understood from  FIG. 8 , in assembly, such catching lugs  32   d  are resiliently engaged with a plurality of projections  31   m  formed on a peripheral portion of the housing  31 . With this, upon assembly, the plastic cover  32  is fixed to the housing  31  in a manner to cover the part containing recess  31   a.    
         [0091]     As is seen from  FIG. 9 , in an inside surface of the cover  32  (viz., the surface that faces the housing  31 ), there is provided a pivot bore  32   a  that serves as a common pivot part.  
         [0092]     To this pivot bore  32   a , there is pivotally connected the override lever  41  that is a selected element. Furthermore, to this pivot bore  32   a , there can be also pivotally connected the child proof lever  70  in case wherein the door latch device is of the child proof type. That is, the override lever  41  and the child proof lever  70 , which are both selected elements, are selectively connected to the pivot bore  32   a . Of course, in place of the pivot bore  32   a , a pivot shaft portion may be used.  
         [0093]     As is seen from  FIG. 9 , the override lever  41  is integrally formed with a shaft portion  41   a  that is rotatably received in the pivot bore  32   a . With this, override lever  41  is pivotally supported by the inside surface of the cover  32 . Upon fixing of the cover  32  to the housing  31 , the override lever  41  becomes aligned with both the transmission lever  46  and the knob lever  35 , and a projection  45   b  formed on the inside lever  45  becomes engaged with an elongate opening  41   c  formed in an arm portion  41   b  of the override lever  41 , as will be understood from  FIG. 1 .  
         [0094]     When, upon manipulation of the inside door handle, the inside lever  45  is turned from the stand-by position (viz., the is position as shown in  FIGS. 7, 8  and  11 ) to the unlocking position (viz., the position as shown in  FIG. 10 ), the override lever  41  is turned from a stand-by position as shown by the two-dot chain line in  FIG. 11  to an unlocking position as shown by the two-dot chain line in  FIG. 10 , so that an actuating portion  41   d  of the override lever  41  is brought into contact with a second engaging portion  11   b  (see  FIG. 21 ) of the open lever  11  thereby turning the open lever  11  toward the unlocking position. With this, irrespective of the condition of the locking/unlocking means, the engaged condition of the latch unit  5  can be released and thus the door can be opened. At the same time, an actuating portion  45   a  formed on an end of the inside lever  45  (see  FIG. 10 ) is brought into contact with a bent portion  19   a  formed on an end of the outside lever  19 , thereby turning the outside lever  19  toward the unlocking position.  
         [0095]     As is seen from  FIG. 9 , on the inside surface of the cover  32 , there are formed two annular portions  32   b  and  32   c  that are snugly mated with ends of the shaft portions  31   f  and  31   g  of the housing  31 . With such mating, the knob lever  35  (see  FIG. 10 ) and the inside lever  45  can be smoothly held by the shaft portions  31   f  and  31   g  respectively.  
         [0096]     As is seen from  FIGS. 2 and 9 , at a lower portion of the cover  32 , there are provided upper and lower connecting arms  32   h . As is best seen from  FIG. 2 , at leading ends of the connecting arms  32   h , there is provided a holding portion  65  by which the ends  39   a  and  40   a  of the two tubes  39  and  40  are tightly connected to the tube fixing portions  60  and  61  of the housing  31 . As is seen from  FIG. 9 , the holding portion  65  is formed with two resiliently deformable pawls  65   a  that are engageable with the generally rectangular opening  31   h  of the housing  31 .  
         [0097]     When it is intended to couple the cover  32  with the housing  31 , the two pawls  65   a  of the holding portion  65  are brought into engagement with the rectangular opening  31   h . With this, the holding portion  65  is stably held between the two tube fixing portions  60  and  61 . As is seen from  FIG. 15 , both ends of the holding portion  65  are pressed against back sides of the first pawl portions  60   a  and  61   a  of the fixed portions  60  and  61 , so that the first pawl portions  60   a  and  61   a  are pressed toward the interior of the groove portions  60   b  and  61   b . Thus, the leading ends of the resilient first pawl portions  60   a  and  61   a  are strongly pressed against the fixing ends  39   a  and  40   a  of the two tubes  39  and  40  that are received in the groove portions  60   b  and  61   b , and thus, the fixed ends  39   a  and  40   a  are tightly fixed in the groove portions  60   b  and  61   b . Upon engagement of the two resilient pawls  65   a  with the rectangular opening  31   h , the leading end of the pawls  65   a  are brought into contact with the inclined lip portion  31   i  of the housing  31  to be guided toward the opening  31   h . Thus, the engagement of the pawls  65   a  with the opening  31   h  is easily and assuredly carried out.  
         [0098]     As is seen from  FIGS. 1, 2 ,  3 ,  5  and  6 , particularly  FIG. 2 , from upper surfaces of the housing  31  and the cover  32  to the two tube fixing portions  60  and  61 , there extends a generally J-shaped plastic top cover  50  for suppressing rain water invasion into the part containing recess  31   a  of the housing  31 . As is seen from  FIG. 1 , the top cover  50  is formed with a plurality of coupling openings  50   a  with which a plurality of projections  31   n  and  32   f  formed on the housing  31  and the cover  32  are engaged, so that the top cover  50  are fixed to both the housing  31  and the cover  32  in such a manner that opposed walls of the top cover  50  receive therebetween peripheral portions of both the housing  31  and the cover  32 .  
         [0099]     In the following, a child proof type door latch device  200  which is a second embodiment of the present invention will be described with reference to FIGS.  25  to  28 .  
         [0100]     Since a latch assembly employed in the door latch device  200  of the second embodiment is the same as the latch assembly  102  employed in the above-mentioned override type door latch device  100  of the first embodiment, explanation of the latch assembly will be omitted from the following description. Furthermore, since, in the second embodiment  200 , a housing ( 31 ), cover ( 32 ) and basic elements mounted in the housing ( 31 ) are substantially same as those employed in the first embodiment  100 , detailed description of such parts will be omitted from the following. That is, in the following, only parts or portions that are different from those of the first embodiment  100  will be described.  
         [0101]     As is seen from  FIG. 25 , in the child proof type door latch device  200  of the second embodiment of the present invention, the child proof lever  70  is used in place of the override lever  41  used in the first embodiment  100 . That is, as is seen from the drawing, the child proof lever  70  is pivotally connected to the pivot bore  32   a . Furthermore, in place of the inside lever  45  in the first embodiment  100 , a child proof inside lever  71  is used which is pivotally connected to the shaft portion  31   g  of the housing  31 . Furthermore, a switch lever  72  is employed which is slidably held on the child proof inside lever  71 .  
         [0102]     As is seen from  FIG. 25 , the child proof lever  70  has a shaft portion  70   a  rotatably received in the pivot bore  32   a  of the cover  32 , and has a pin portion  70   b  that projects outward through an opening  32   g  formed in the cover  32 .  
         [0103]     That is, when the pin portion  70   b  is actuated, the child proof lever  70  is pivoted between a locking position as shown by the two-dot chain line in  FIG. 27  and an unlocking position as shown by the two-dot chain line in  FIG. 28 .  
         [0104]     When the cover  32  is properly fixed to the housing  31 , an elongate slot  70   c  formed in the child proof lever  70  puts thereinto a projection  72   b  formed on the switch lever  72 . Thus, in accordance with a pivotal movement of the child proof lever  70 , the switch lever  72  is moved between an unlocking position as shown in  FIG. 28  wherein an actuating end  72   a  of the switch lever  72  is contactable with the bent portion  19   a  of the outside lever  19  (see  FIG. 10 ) and a locking position as shown in  FIG. 27  wherein the actuating end  72   a  is not contactable with the bent portion  19   a  (see  FIG. 11 ).  
         [0105]     When, with the child proof lever  70  and the switch lever  72  assuming their unlocking positions and with the locking/unlocking means assuming its unlocking condition, the inside door handle is manipulated, the child proof inside lever  71  is operated to carry out a canceling operation. That is, upon this, the switch lever  72  and the child proof inside lever  71  are operated to carry out their canceling operation thereby to cancel the engaged condition of the latch unit  5 .  
         [0106]     While, when, with the child proof lever  70  and the switch lever  72  assuming their locking positions, the inside door handle is manipulated, the switch lever  72  strikes air against the bent portion  19   a  of the outside lever  19  irrespective of the condition of the locking/unlocking means. Thus, in this case, the outside lever  19  can not be turned toward the unlocking position, and thus, the engaged condition of the latch unit  5  can not be cancelled.  
         [0107]     In general, the child proof type door latch device is applied to rear doors that are not provided with a key cylinder. Thus, in this second embodiment  200 , there are no members that correspond to the key lever ( 36 ) and the rotary switch ( 47 ) that are used in the above-mentioned first embodiment  100 . Accordingly, in this second embodiment  200 , the key lever receiving bore  31   b  (see  FIG. 27 ) and the through bore  31   j  of the housing  31  are inoperative, that is, plugged with a plastic screen. Plugging the through bore  31   j  is easily achieved by putting a suitable insert into a cavity of a die assembly in the injection molding of the housing  31 .  
         [0108]     The entire contents of Japanese Patent Application 2004-218567 filed Jul. 27, 2004 are incorporated herein by reference.  
         [0109]     Although the invention has been described above with reference to the embodiments of the invention, the invention is not limited to such embodiments as described above. Various modifications and variations of such embodiments may be carried out by those skilled in the art, in light of the above description.