GB2268968A - Lock mechanism with improved burglary resistance. - Google Patents

Abstract

A cylinder lock mechanism with improved burglary resistance, including a lock body (5) housing a turnable lock cylinder (6) enclosing a set of locking discs (7) and an elongate locking bar (8), which in its locked position is partly located in a groove (9) in the inner surface of the lock body (5) and partly in a slot (10) in the lock cylinder (6) to prevent turning of the lock cylinder (6) relative to the lock body (5). The slot (10) in the lock cylinder (6) is provided with at least one protrusion (13) extending transversely with regard to the slot (10) and arranged preferably in the inner end thereof. The locking bar (8) is provided with a depression (14) arranged to cooperate with the protrusion (13) and prevent displacement of the locking bar (8) in the elongate direction thereof out from the slot (10) in the lock cylinder (6). <IMAGE>

Description

t 2268968 LOCK HECH MI SM WITH IMPROVED BURGLARY RESISTANCE The invention

relates to a lock mechanism with improved burglary resistance which includes a lock body housing a turnable lock cylinder and an elongate locking bar, which in its locked position is partly located in a groove in the inner surface of the lock body and partly in a slot in the lock cylinder to prevent turning of the lock cylinder relative to the lock body, and a set of locking discs inside the lock cylinder, which by means of an appropriate key are turnable into a position, in which they allow movement of the locking bar partly through said slot in the lock cylinder into a position, in which the lock cylinder is freed to turn relative to the lock body. Such a lock mechanism will hereafter be referred to as a "lock mechanism of the kind described".

In a lock mechanism of the kind described, burglary resistance has been improved i.a. by placing different protection plates or the like drillresistant elements in front of the set of locking discs to make it more difficult to get access to the locking bar of the lock by means of drilling. Depending on the application, due to space requirements substantially straight-formed locking bars are commonly used in a lock mechanism of the kind described. In this case if drilling is successfully carried out at the position of the locking bar, the locking bar can be pulled out f rom the lock in its axial direction and the lock can then be opened without a key.

An aim of the invention is to make it more difficult to crack the lock, especially when the above-described lock- cracking technique is attempted, by preventing illicit removal of the locking bar from the lock. A further aim is to provide. a solution for the above purpose, which is advantageous from the viewpoint of manufacture and the costs incurring therefrom.

These aims can be met in accordance with the invention by providing the slot in the lock cylinder with at least one protrusion extending tran sversely with regard to the slot and arranged preferably in the inner end thereof, the locking bar being provided with a corresponding depression arranged to cooperate with the at least one protrusion so as to prevent displacement of the locking bar in its elongate direction out from the slot in the lock cylinder. Because the locking bar is always partly located in the slot in the lock cylinder the interengagement of the protrusion(s) and depression prevent illicit removal of the locking bar by pulling it out of the slot f rom one end. The improved burglary resistance provided by this invention does not, however, affect in any way the operation of the actual lock mechanism, since the locking and unlocking movements of the locking bar relative to the lock cylinder occur in the radial direction of the lock.

Preferably a protrusion is provided on both sides of the slot in the lock cylinder, and conveniently the protrusions are arranged to be located opposite each other in the elongate direction of the slot so that they can be received in a single continuous groove in the locking bar. In principle there can of course be several protrusions arranged in successive order along the slot. Limitations for this are in the first place set by the production technique and the additional costs resulting therefrom.

A particularly advantageous solution with a view to production techniques and costs is obtained, when the locking bar is substantially circular in cross-section and a groove is arranged to extend completely around the locking bar. A groove having annular sides normal to the axis of a straight circular cross-section locking bar is particularly preferred.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: - Figure 1 is a sectional view of a cylinder lock mechanism according to the invention in a certain operational environment, Figure 2 shows, partly in section, a lock cylinder and a locking bar pertaining to the lock mechanism of Figure 1, and Figure 3 shows a part-section on line III-III of Figure 2.

In Figure 1 a cylinder lock mechanism 15 according to the invention is shown located, by way of example, in a casing-like body 1, of which only a part is shown. The body 1 includes a key opening 2, through which a key for the lock mechanism is inserted into the lock. The mechanism 15 includes further elements 3 and 4 serving as drill-resisting members. The lock mechanism includes a lock body 5 housing a turnable lock cylinder 6 enclosing a set of locking discs 7 turnable by means of the key (not shown). The lock mechanism includes also a locking bar 8, which in its locked position is partly located in a groove 9 in the inner surf ace of the lock body 5 and partly in a slot 10 in the lock cylinder 6 thereby preventing turning of the lock cylinder 6 with regard to the lock body 5.

In accordance with the known operating principle of this type of locking mechanism the locking discs 7 are separately turnable by means of the key into a position, in which notches at the periphery thereof, not shown in the drawings, f orm a unif orm channel at the position of the slot 10 f or the locking bar 8 to be partly entered therein in order to thereby release the lock cylinder 6 to turn with the key relative to the lock body 5. In thi s way a cam element 11 fixed to a force transmitting part 6a of the lock cylinder 6 will also be turned, whereby the space locked by the lock mechanism 15 can be opened. The mechanism 15 shown in Figure 1 also includes a ball-like drill-resisting member 12 in an inner part of the lock cylinder 6.

As is more clearly disclosed in Figures 2 and 3, the slot 10 in the lock cylinder 6 is provided with at least one protrusion 13 (two protrusions 13 are shown) extending transverse to the slot 10, which is located towards the inner end of the lock cylinder 6. The locking bar 8 is provided with a groove 14 for receiving the at least one protrusion 13. The groove illustrated is of substantially rectangular cross-section providing spaced-apart annular faces 14a, 14b (against which the protrusions 13 bear) which are normal to the longitudinal axis of the bar 8. Thus, the locking bar 8, which is always partly located in the slot 10, can be moved in the radial direction of the lock cylinder 6 as required for opening and closing of the lock mechanism 15, but axial movements in the direction of the slot 10 are prevented. Thus, if it were possible, in spite of the presence of the drill-resisting members 3 and 4, to make a hole in the body 1 at the position of the locking bar 8 with the intention of pulling the locking bar 8 out of the body 5, the interengagement of the integers 13 and 14 will prevent this.

It will be appreciated that the integers 13 and 14 can be formed in different ways, they can be located in different positions and there can be several of them. The essential thing is that they prevent a sufficient displacement of the locking bar 8 in the axial direction thereof to release the lock mechanism. Hence, the invention is not limited to the specific embodiment of mechanism illustrated since other arrangements of protrusion(s) 13 and groove 14 are feasible within the scope of the following claims.

Claims (5)

1 A cylinder lock mechanism with improved burglary resistance, including a lock body housing a turnable lock cylinder and an elongate locking bar, which in its locked position is partly located in a groove in the inner surface of the lock body and partly in a slot in the lock cylinder to prevent turning of the lock cylinder relative to the lock body, and a set of locking discs inside the lock cylinder, which by means of an appropriate key are turnable into a position, in which they allow movement of the locking bar partly through said slot in the lock cylinder into a position, in which the lock cylinder is freed to turn relative to the lock body, wherein the slot in the lock cylinder is provided with at least one protrusion extending transversely with regard to the slot, and the locking bar is provided with a corresponding depression arranged to cooperate with the at least one protrusion so as to prevent displacement of the locking bar in its elongate direction out from the slot in the lock cylinder.

2. A lock mechanism according to claim 1, wherein a protrusion is provided on either side of the slot in the lock cylinder and the depression is a groove surrounding the locking bar.

3. A lock mechanism according to claim 1 or claim 2, wherein the at least one protrusion is provided towards the inner end of the lock cylinder.

4. A lock mechanism according to any preceding claim, wherein the locking bar is substantially round in crosssection and the depression is a groove of substantially rectangular cross-section extending around the locking bar.

5. A lock mechanism substantially as hereinbefore described with reference to the accompanying drawings.