Self-shut type lock device

A self-shut type lock device comprising a self-shut protector provided in the keyhole capable of hiding the lower tumbler segments from being picked through the keyhole.

BACKGROUND OF THE INVENTION 
The present invention relates to a self-shut type lock device, and more 
particularly to an improved lock device comprising a movable self-shut 
protector overslipped in the keyhole, capable of hiding the lower tumbler 
segments and preventing the same from being picked through the keyhole. 
There are various kinds of conventional lock devices, but their 
construction are almost the same in principle. Generally the common 
drawback is that the keyholes are all open-type and that, if peeped 
through the keyhole, the profile configuration of the pin tumblers will be 
visible from outside so that the burglar can easily imitate or utilize his 
self-made master keys and other tools (such as a probe or steel wire) and 
detect the profile configuration of the lock's opening directly in a short 
time and then proceed to open it stealingly, making it not anti-burglar at 
all. 
SUMMARY OF THE INVENTION 
The primary objective of the present invention is to eliminate the above 
drawbacks and to provide an improved lock device with structural 
sophistication and absolute anti-burglar function in achieving the aim of 
full prevention of stealingly opening by somebody else.

DETAILED DESCRIPTION OF THE DRAWINGS 
For the purpose of description, suppose four pin tumblers in the keyhole of 
the embodiment of the present invention are illustrated, and if desired, 
the number of them may be varied according to requirements. 
As shown in the figures, the lock device of the present invention comprises 
the lock body 10 having a longitudinal central opening 10A, and a square 
tumbler-hole 11 and pin tumbler-holes 12, 13, 14, 15 perpendicular to the 
axis are cut in sequence on the internal circular face of said central 
opening 10A and communicating with one another. In said cylinder 20 is cut 
a keyhole 21 at its center, and on the outer circumference thereof is cut 
an "U-shaped" protector groove 26 communicated with said keyhole 21, 
thereby in whose center a tumbler-seat 27 is projecting out of the 
cylinder 20. Said tumbler-seat 27 is similarly cut a plurality of lower 
tumbler-holes 22, 23, 24, 25 with pin grooves 22D, 23D, 24D, 25D on its 
side wall, respectively, which are also communicated with the keyhole 21. 
The protector 28 with its stop-arms 283--283 having an "U-shaped" top 
configuration are previously overslipped into said "U-shaped" groove 26 of 
the cylinder 20, and the lower tumblers 22A, 23A, 24A, 25A fitted with 
their respective locking pins 22C, 23C, 24C, 25C are overslipped in the 
lower tumbler-holes 22, 23, 24, 25 of the cylinder 20 so that said locking 
pins 22C, 23C, 24C, 25C are movable within pin-grooves 22D, 23D, 24D, 25D, 
respectively. Further upper tumbler-holes 11, 12, 13, 14, 15 are formed by 
extending its depth into said lock body 10 and are in sequence overslipped 
with springs 11B, 12B, 13B, 14B, 15B and upper tumblers 11A, 12A, 13A, 
14A, 15A, respectively. In this manner, said cylinder 20 is rotatably 
mounted in said central opening 10A of the lock body 10 so as to have each 
respective upper tumbler-holes 12, 13, 14, 15 just in alignment with their 
respective lower tumbler-holes 22, 23, 24, 25. In general, the protector 
28 is exactly to make its top 282 flush with the outer surface of the 
cylinder 20, while the height of lower tumblers 22A, 23A, 24A, 25A are 
different with one another, and finally the external surface of the lock 
body 10 is secured by a rigid housing (not shown), thus making the members 
of whole lock-device integrated closely as one piece. 
The section of the key 50 according to the present invention is made 
matching with that of the keyhole, one side of whose front end 51 is 
arched and on whose longer wide face 52 is cut an "U-shaped" groove 53 
capable of being overslipped into said protector 28, at the center of the 
groove 53 a series of wavy grooves 54, 55, 56, 57 with different depth 
being cut from the key body, and the depth of said grooves depending upon 
the height of corresponding lower tumblers so as to match with each one 
for achieving opening of the lock device. 
When the key 50 is immediately inserted into the keyhole 21 and contacted 
with the arched portion 281 of the protector 28, pushing it upward as 
shown in FIG. 3, the top 282 of said protector 28 extends into the square 
tumbler-hole 11, and at the same time the stop-arm 283 of said protector 
28 stops all the locking pins 22C, 23C, 24C, 25C, making lower ends of 
said lower tumblers 22A, 23A, 24A, 25A flush at the same height and 
contracted into their respective lower tumbler-holes along with said 
protector 28. Hence, if a burglar wishes trying to open the lock device of 
the present invention with a master key or other tools he cannot peep out 
the opening position of the lower tumblers 22A, 23A, 24A, 25A, and this is 
an important and a distinguishing characteristic of the present invention. 
When the key 50 is completely inserted into the keyhole 21 the protector 28 
passes through the U-shaped grooves 26 and 53 by means of the action of 
spring 11B and recover itself in original place, making its top 282 
re-flush with the outer surface of cylinder 20, and after the 
lower-tumblers 22A, 23A, 24A, 25A run against simultaneously the wavy 
grooves 54, 55, 56, 57, the top of lower tumblers 22A, 23A, 24A, 25A are 
raised by exactly the amount correct to bring their tops flush with the 
outer surface of cylinder 20, as shown in FIG. 4, indicating that said 
cylinder 20 is freely rotatable and capable of releasing the door-bolt 
(not shown). Furthermore, whenever a small force is applied to the end 
concave rim 58--58 of the key 50, the arched portion 284--284 at the end 
of stop-arms 283--283 of the protector 28 and itself are readily withdrawn 
out. 
It will be understood that if the locking pins on said lower tumblers are 
ommitted, said protector may also provide a self-shut means for preventing 
the cylinder from being rotated, because any raising or picking from the 
lower protion of said protector will push the height of the top of said 
protector over the outer circumference of said cylinder and therefore 
achieving the self-shut purpose of the present invention. 
It is to pointed out that as the pin grooves only formed on the side wall 
of said lower tumbler-holes in the cylinder rather than extending through 
the upper tumbler-holes, the maximum movable range of said locking pins 
and the long stop-arms of said protector are thereby limited within said 
cylinder. This is one of important features of the present invention for 
providing an absolute anti-burglar function.