Child-proof for vehicle sliding door latch device

A latch device for a sliding door comprises front and rear latch units attached to front and rear edge portions of the sliding door, respectively, a relay provided within the sliding door for coupling between the latch units and outer and inner open handles of the door, a child-proof mechanism provided on the relay and displaceable between a child-proof condition and a non-child-proof condition, a child-proof lever for displacing the conditions of the child-proof mechanism. The child-proof lever has an operation knob exposed to the outside of the sliding door through an opening formed in a front peripheral plate of the door. The child-proof lever is rotatably mounted to the front latch unit and is connected with the child-proof mechanism through a first rod.

BACKGROUND OF THE INVENTION 
The present invention relates to a latch device for a vehicle sliding door, 
and in particular to a child-proof device attached to such a latch device. 
PRIOR ART OF THE INVENTION 
FIG. 1 shows a side surface of a vehicle having a sliding door in which a 
prior art sliding door latch device is incorporated. The prior art door 
latch device used for the sliding door C which is slidably engaged with a 
guide rail B fixed to a side surface of a vehicle body A has a front latch 
unit D attached to a front edge portion of the sliding door C for engaging 
with a front striker (not shown) of the vehicle body A, and a rear latch 
unit D' attached to the rear edge portion of the door C for engaging with 
a rear striker (not shown) of the vehicle body A. An outer open handle E 
and an inner open handle F are relatively connected with the latch units D 
and D' so that an opening operation of the handle E or F can cause the 
latch units to be released from the strikers. 
If the front latch unit D is directly connected to the open handles E and F 
through more than two rods, and if the rear latch unit D' is directly 
connected to the handles E and F through more than two rods, a narrow 
internal space of the sliding door C would be crowded with a plurality of 
rods. In order to solve this problem, a relay means G has been 
conventionally provided in the internal space of the door C for coupling 
between the latch units and the open handles. 
The relay means G has a well-known locking mechanism which is connected 
with a door key cylinder H and an inside lock button K and is displaceable 
between a locked condition for disabling an opening operation of the 
handles E and F and an unlocked condition for enabling the opening 
operation of the handles. The relay means G also has a child-proof 
mechanism which is displaceable between a child-proof condition for 
disabling an opening operation of the inner open handle F and a 
non-child-proof condition for enabling the opening operation of the inner 
open handle F (referring to Japanese Patent Publication No. 58-25155). 
An operation knob L for switching the conditions of the child-proof 
mechanism has to be located at a position where it cannot be manipulated 
when the sliding door C is closed but it can be simply manipulated when 
the sliding door C is opened. Accordingly, an opening portion N through 
which the operation knob L is exposed to the outside of the door, is 
formed in the front peripheral plate M of the sliding door C. 
The relay means G shown in FIG. 2 is located in the vicinity of the opening 
portion N so that the operation knob L attached to the relay means G can 
reach the opening portion N. However, since the open handles E and F, the 
key cylinder H and the inside lock button K which should be connected with 
the relay means G are arranged at various positions among doors, it is 
desirable to appropriately arrange the relay means G, depending upon the 
positions of these components. 
SUMMARY OF THE INVENTION 
The present invention is devised in order to optionally locate the relay 
means at an optimum position, depending upon positions where the open 
handles, the key cylinder and the lock button.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Explanation will be made of an embodiment of the present invention with 
reference to the accompanying drawings. A sliding door 1 which is opened 
and closed by moving in front-and-rear direction along a guide rail 3 of a 
vehicle body 2 has an outer open handle 4, an inner open handle 5, a door 
key cylinder 6, and an inside lock button 7. A front latch unit 10 is 
mounted at the front edge portion of the door 1 for engaging with a front 
striker 8 (FIG. 4) fixed to the vehicle body 2. A rear latch unit 11 is 
mounted at the rear edge portion of the door 1 for engaging with a rear 
striker 9 fixed to the vehicle body 2. When the latch units 10 and 11 are 
engaged with the strikers 8 and 9, the sliding door is held in a door 
closed condition. 
A relay means 12 for coupling between the open handles 4 and 5 and the 
latch units 10 and 11 is provided in the sliding door 1. The latch device 
according to the present invention is composed of the latch units 10 and 
11 and the relay means 12. 
The details of the relay means 12 is shown in FIG. 6. The relay means 12 
has a base plate 13 which is secured to a metal inner plate 14 (FIG. 5) of 
the sliding door 1. An outer open lever 16 (FIG. 7) is rotatably 
journalled to the plate 13 by a shaft 15. The open lever 16 has a arcuate 
hole 17 centered at the shaft 15, with which a bent portion of a rod 18 
extending to the outer open handle 4 is engaged. The open lever 16 also 
has an L-shaped hole 19 with which a pin 21 fixed to a left end of a lock 
link 20 is engaged. 
A latch lever 22 is journalled to the shaft 15 so as to overlap with the 
open lever 16. As shown in FIG. 8, the latch lever 22 has a slot 23 with 
which the pin 21 is engaged. The slot 23 extends radially of the shaft 15, 
and is superposed with an engaging part 19a of the L-shaped hole 19. The 
front latch unit 10 is connected with the latch lever 22 through a rod 24, 
and the rear latch unit 11 is connected with the latch lever 22 through a 
rod 25. The latch units 10 and 11 release the strikers 8 and 9 when the 
latch lever 22 is turned counterclockwise in FIG. 6. 
As the pin 21 of the lock link 20 is located in the engaging part 19a of 
the hole 19, the relay means 12 comes into an unlocked condition, and 
accordingly, a counter-clockwise rotation of the outer open lever 16 is 
transmitted to the latch lever 22 through the pin 21. However, as the pin 
21 is located in a free-play part 19b of the L-shaped hole 19, the relay 
means 21 comes into a locked condition, and accordingly, the 
counterclockwise rotation of the outer open lever 16 is not transmitted to 
the latch lever 22, therefore precluding opening of the door. 
A lock lever 27 is rotatably mounted on the base plate 13 by a shaft 28. 
The right end of the lock link 20 is pivoted to the lock lever 27 by a pin 
26. The lock lever 27 and the key cylinder 6 is connected to each other by 
a rod 29, and the lock lever 27 and the inside lock button 7 is connected 
to each other by a rod 30. When the lock lever 27 is turned by means of 
the operation of the key cylinder 6 or the inside lock button 7, the lock 
link 20 is slidably displaced between the locked position and the unlocked 
position. It is noted that in the unlocked condition the pin 26 is 
superposed with the shaft 15 as shown in FIG. 6. 
An actuator 31 which is fixed to the base plate 13 has a drive lever 32 
engaged with the lock lever 27. 
An L-shaped inner open lever 33 is rotatably attached to the base plate 13 
by means of the shaft 15. A bent piece 35 which is engaged with the 
peripheral edge of an opening 34 of the base plate 13 is formed on one end 
portion of the inner open lever 33. 
A rotary member 36 is rotatably attached to a shaft 61 to the reverse side 
of the base plate 13. As shown in FIG. 4, the relay means 12 is desirably 
arranged at a position where it is substantially superposed with the inner 
open handle 5, and the inner open handle 5 is directly coupled to the 
rotary member 36 with no rod therebetween. Accordingly, the necessity of a 
one rod can be eliminated. A tip end 37 of the rotary member 36 is opposed 
to the bent piece 35. 
The inner open lever 33 has an elongated hole 38 extending radially of the 
shaft 15. A pin 40 fixed to one end of a child link 39 is engaged in the 
elongated hole 38. The other end of the child link 39 is journalled to a 
crank lever 41 which is coupled with a rod 43 extending to a child-proof 
lever 42 shown in FIG. 9. The lever 42 is displaced between a 
non-child-proof position where the pin 40 of the link 39 can be engaged 
with an engaging arm 44 of the outer open lever 16, and a child-proof 
position where the pin 40 cannot be engaged with the engaging arm 44. 
When the inner open lever 33 is turned counterclock-wise through the 
intermediary of the rotary member 36 by the opening manipulation of the 
inner open handle 5 under the non-child-proof condition, the pin 40 
engages with the engaging arm 44 to thereby turn the outer open lever 16 
counterclockwise. At this time, if the lock lever 27 is in the unlocked 
position, the counterclockwise rotation of the outer open lever 16 causes 
the latch units 10 and 11 to release the strikers 8 and 9 and thereby the 
door is open. 
On the contrary, when the child-proof lever 42 is located at the 
child-proof position, even though the inner open lever 33 is turned 
counterclockwise by the door opening manipulation of the inner open handle 
5, the pin 40 cannot engage with the arm 44 of the outer open lever 16. 
Therefore, the door cannot be open even though the lock lever 27 is 
located at the unlocked position. 
FIG. 9 shows the front latch unit 10. The front latch unit 10 is composed 
of a latch or fork 45 adapted to be engaged with the striker 8, and a 
ratchet or pawl 46 engaged with the latch 45 so as to prevent the latch 45 
from reversely turning. The latch 45 and the ratchet 46 are rotatably 
received in a resin body 49 by means of shafts 47 and 48, respectively. 
The resin body 49 is sandwiched between two metal cover brackets 51 and 52 
which are attached to a front peripheral plate 54 of the inner plate 14 
(FIG. 5) of the door by means of bolts 53 or the like. 
The metal bracket 51 is rotatably journalled thereto with a rotary lever 55 
which is coupled with the rod 24 extending to the latch lever 22. A tip 
end of the rotary lever 55 is opposed to a protrusion 56 of the ratchet 
46. 
The child-proof lever 42 is journalled by means of a pin 59 to a 
sub-bracket 58 which is integrally formed with the metal bracket 51. An 
operation knob 57 of the child-proof lever 42 is projected outward of the 
door through an opening 60 formed in the front peripheral plate 54. 
In the arrangement according to the present invention, as mentioned above, 
the relay means 12 incorporating the child-proof mechanism, is secured to 
the inner plate 14 of the sliding door 1 by means of bolts and the like, 
taking into consideration of the positions of the outer and inner open 
handles 4 and 5, the door key cylinder 6, the inside lock button 7 and the 
front and rear latch units 10 and 11. Preferably, the relay means 12 is 
located at the center among the above-mentioned components, or at a 
position where it superposed with the inner open handle 5. With this 
arrangement, a plurality of rods for coupling the relay means 12 with the 
components are prevented from being jumbled, and can be arranged in order 
with the internal space of the door 1. 
Further, since the child-proof lever 42 is rotatably journalled to the 
front latch unit 10, the attachment of the child-proof lever 42 can be 
completed only by securing the front latch unit 10 to the front peripheral 
plate 54. Accordingly, it is possible to eliminate the necessity of a 
member for attaching the child-proof lever to the sliding door.