The present invention relates to a lock (3) on the inside of a door, wherein the lock can be actuated from outside the door. The lock is connected to a locking device (14) on the outer side of the door by a coupling rod (12). In order to increase protection against burglaries, the coupling rod (12) is to pass through a channel (22) with which a channel closure jaw (28) is associated. The jaw is supported on the coupling rod (12) and is under spring-load in the direction of closure. Removal of the coupling rod during a burglary attempt results in a closure of the channel with protection of the lock from tampering by the jaw.

FIELD AND BACKGROUND OF THE INVENTION 
The present invention relates to a lock which can be actuated from the 
outer side of a door or the like and which is connected to the closing 
means on the outer side of the door by a coupling rod or the like. 
In such locks a considerable lack of security resides in the fact that 
after a forceful removal of the closing means on the outer side of the 
door, the lock can be actuated by a tool so as to bring it into the open 
position. Upon removal of the closing means, the opening of the lock which 
receives the coupling rod is exposed so that a tool--for instance, a 
screwdriver--can engage in it. 
SUMMARY OF THE INVENTION 
It is therefore the object of this invention so to develop a lock of the 
type in question in a manner which is simple to manufacture and more 
secure against unauthorized opening and such that, after removal of the 
closing means on the outer side of the door, the lock-side opening for the 
coupling rod can no longer be reached. 
According to the invention the coupling rod (12) passes through a channel 
(22) with which there is associated a channel closure jaw (28) which rests 
on the coupling rod (12) and is spring-loaded in the direction of closure. 
As a result of this development, a lock of the type described which affords 
increased security is created. Upon the forceful removal of the locking 
device on the outer side of the door with simultaneous removal of the 
coupling rod, the rod leaves the channel so that the channel-closure jaw 
which is urged by spring in the closing direction comes into a 
channel-closing position. It is then impossible to reach with a tool 
through the channel from outside the door in order to reach the opening in 
the lock which previously still received the coupling rod. Even the 
coupling rod can then no longer be introduced from the outer side of the 
door due to the fact that the closure jaw has entered into the channel. 
This securing against unauthorized opening in the manner described above 
can be achieved with inexpensive means. 
It is particularly advantageous to arrange the channel in the bushing. The 
latter is so inserted in an opening in the door that the bushing cannot be 
pulled out from the outer side of the door. Nor can it be pushed towards 
the inner side of the door due to the lock present there. This bushing 
serves at the same time to receive the channel closure jaw which can be 
displaced in the transverse slot. The jaw has the shape of a wall segment. 
When the coupling rod has been inserted, said wall segment is supplemented 
by the remaining cross-section of the bushing at the height of the 
transverse slot so as to form a circle. When the coupling rod leaves the 
channel, the wall segment or the channel closure jaw is displaced in 
inward direction and accordingly extends into the channel in such a manner 
that application of a tool does not permit displacement of the channel 
closure jaw into a release position. 
The spring which acts on the channel closure jaw is also developed very 
simply and economically from a structural standpoint. For this purpose, an 
elastic spring ring has been selected which surrounds the bushing and the 
jaw, it gripping around the jaw at the height of the transverse slot. As a 
result, the jaw constantly endeavors to close off the channel. In order 
nevertheless to make it possible, after the installation of the bushing 
and closure jaw, to insert the coupling rod from the outer side of the 
door, the channel closure jaw has a run-on bevel on its flank facing the 
inner side of the door. Before insertion of the coupling rod, a tool 
inserted from the inner side of the door strikes against said run-on bevel 
together with an outward displacement of the channel closure jaw. By 
pushing the tool back, the coupling rod can then pass through the channel. 
The closure rod then acts as a clamping body on the closure rod so that a 
clamping seat of the bushing with closure jaw on the coupling rod is 
created. 
Large pull-out forces acting on the bushing can be taken up without damage 
due to the fact that the bushing has a plate-shaped flange on its front 
side facing the inner side of the door. This flange is preferably integral 
with the bushing. If the transverse slot in the bushing completely passes 
through the channel and the bottom of the transverse slot terminates on 
the other side of the channel wall, then the closure jaw cannot be shifted 
from the outer side of the door even by a very pointed or knife-like 
burglary tool.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A door, designated 1, bears on its inner side 2 a case-like lock 3 of 
customary construction. The latter contains a bolt 4 which can be advanced 
and retracted. The bolt can be actuated from the inner side of the door by 
means of a lock cylinder (not shown) which is arranged in a front-side 
housing projection 5 of the lock 3. 
The lock inner mechanism is covered by a lock cover 6 adjacent the inner 
side 2 of the door 1, the lock cover being attached to the lock housing 8 
by screws 7. 
The lock cover 6 bears a turnable driver 9 which is functionally connected 
with the lock mechanism by means of a pin 10 extending into the lock. The 
turnably mounted drive 9 has an opening 11 of rectangular cross section 
which extends in axial direction. This opening is adapted to the 
cross-section of a coupling rod 12 which connects the lock 3 to a closing 
means 14 arranged on the outer side 13 of the door. The closing means can 
be one which can be actuated after insertion of a magnetically coded key 
card (not shown). For this there is used an outer turn knob 15 associated 
with the closing means 14 and which, after insertion of the proper key 
card, comes into coupling engagement with a nut 16 of the closing means 
14. The bolt 4 can thereby be advanced and retracted. 
The nut 16 bears a square mandrel 17. A slot 18 provided in the front end 
of said mandrel receives the end 19 of the coupling rod 12 which is 
located on the outer side of the door. By a transverse pin 20 which passes 
both through the square mandrel 17 and through the end 19 of the coupling 
rod 12, the two are connected together to form a single unit. 
The end 21 of the coupling rod 12 which is located on the inner side of the 
door passes through a channel 22 and enters, with form-lock, into the 
opening 11 of the rotatably mounted drive 9. The channel 22 in front of 
the drive 9 is arranged in a bushing 24. The front side of said bushing 
which faces the inner side 2 of the door has a plate-shaped flange 25 
which is received by a recess 26 provided on the inner side of the door. A 
bore 27 adjoins the recess 26, the bushing 24 extending into said bore. As 
a result of this development, the bushing 24 cannot be pulled out in the 
direction towards the outer side of the door due to the fact that it is 
supported on the inner side 2 of the door. 
A channel closure jaw 28 is associated with the channel 22. The channel 
closure jaw is spring-urged in the direction of closure and rests against 
the wide surface of the coupling rod 12 which faces it. The channel 
closure jaw 28 has the shape of a wall segment which rests in a transverse 
slot 29 in the bushing 24. This transverse slot 29 passes through the 
entire channel cross section and extends up to the corresponding channel 
wall 22, At the height of the transverse slot 29, the bushing is provided 
with an annular groove 30 which continues into a partial annular groove 31 
of the wall segment or the channel closure jaw 28. At the height of the 
annular groove 30 and of the partial annular groove 31, the closure jaw 28 
and the bushing 24 are surrounded by an elastic spring ring 32. In this 
embodiment the latter consists of rubber and is placed-on with tension so 
that the closure jaw 28 endeavors to move in the direction of the channel 
wall 22'. If the coupling rod 12 is not in the channel 22, then the wall 
segment applies itself, due to the spring-load, with its chord-like 
extending surface F against the channel wall 22'. 
The insertion of the coupling rod 12 from the outer side of the door can 
nevertheless take place even when the closure jaw 28 is mounted, due to a 
control bevel 33 provided on its flank which bevel faces the inside of the 
door. Before insertion of the coupling rod 12 into the channel 22, the 
control bevel 33 is acted on, for instance by the blade of a screwdriver 
inserted from the inner side of the door, with simultaneous radial outward 
displacement of the channel closure jaw 28 against the force of the spring 
ring 32. The passage for the coupling rod 12 is in this way opened, the 
rod pushing the blade of the screwdriver back upon its insertion. This 
control bevel 33 can also be of importance if, instead of a connection of 
the coupling rod 12 to the square mandrel 17 by a pin 20, an irreversible 
plug/detent connection is provided. The coupling rod 12 can then be 
installed also from the inner side of the door, its end striking against 
the control bevel 33 of the closure jaw 28 and displacing it. 
As an alternative, before the first mounting, the closure jaw 28 can also 
be held in the release position by a filler piece which, upon insertion of 
the coupling rod 12 from the outer side of the door, is pushed out of the 
channel 22 by the end of the coupling rod 12. For this purpose, the filler 
piece is made shorter than the bushing 24 so as to obtain a threading 
effect. 
If the closing means 14 is removed during an attempted burglary, then the 
coupling rod 12 simultaneously leaves the opening 23 of the drive 9 as 
well as the channel 22. As soon as the channel closure jaw 28 no longer 
finds any support on the coupling rod 12, the closure jaw 28 is displaced 
radially inward by the spring ring 32 until it rests with its chord-like 
surface F against the channel wall 22'. It is then no longer possible to 
reach through the channel 22 by means of a burglary tool, a screwdriver or 
the like, in order to turn the driver 9. 
The transverse slot could also be cut so deep that the closure jaw 28 rests 
in its locking position beyond the channel wall 22'. The displacement path 
of the closure jaw 28 is, in this case, greater than the thickness of the 
channel 22.