GB2054028A - Cylinder lock - Google Patents

Abstract

A cylinder lock having conventional radially acting pin tumblers 19 has additional axially acting pin tumblers 16, 17 for cooperation with a radial face of the cylinder 9, the additional tumblers being displaceable by a suitably shaped end surface of the key 18. <IMAGE>

Description

SPECIFICATION A cylinder lock and key therefor This invention relates to a cylinder lock having increased resistance to picking and to a key adapted to open the lock.

A conventional cylinder lock comprises a cylinder housed rotatably within a body and restrained against rotation by tumblers which interlock the peripheral surface of the cylinder and the body of the lock. Insertion of a suitably shaped key releases the tumblers, thereby permitting rotation of the cylinder as the key is turned and opening of the latch by way of a connection between the cylinder and the latch mechanism. In one form of cylinder lock, the tumblers consist of a row of segmented pins, each housed in aligned bores in the peripheral surface of the cylinder and the internal surface of the body. One segment of each pin projects from the body into the cylinder and the other lies wholly within the cylinder when the lock is secured.Insertion of the key displaces the pins against spring force to bring the meeting ends of the segments of each pin into a position flush with the peripheral surface of the cylinder, so that the latter may be freely rotated. By giving the pin segments normally received wholly in the bores in the cylinder different lengths, it may be arranged that each lock may be opened by a unique key. Other mechanisms, conveniently referred to herein as securing means, may be used to interlock the cylinder and the body of the lock.

A disadvantaged of a conventional lock is the relative ease with which the tumblers may be released by the insertion of a blade or other unauthorised key-shaped implement. To render a cylinder lock more pick-resistant, one aspect of the present invention provides at least one additional tumbler which acts on the cylinder at the rear end of the key slot, the additional tumbler or tumblers being releasable by a suitably shaped end portion of the key. To pick the lock, two or three blades must be inserted to raise the tumblers conventionally provided and to shift the additional tumbler or tumblers, this being a difficult operation to perform.

Conveniently, the or each additional tumbler is in the form of a segmented pin received in axially aligned bores in the cylinder and body or, more preferably, in separate parts fast with the cylinder and body, respectively. A spring in the or each bore in the body or the part fast therewith urges the pertaining pin in the forward direction (i.e.

towards the entry to the key slot), so, that upon insertion of the key, the pin is pressed into a position in which the meeting ends of the pin segments align with a radial face of the cylinder or the part fast therewith. In the event that two or more additional tumblers are provided, the pin segments which are normally received wholly within the bores in the cylinder or the part fast therewith may have different lengths and the end of the key is suitably shaped. Upon release of all the pin tumblers conventionally and additionally provided, rotation of the cylinder and opening of the latch may take place in the normal way.

In a construction in which at least one additional pin tumbler is housed within a part separate from the lock body, the cylinder may have a circumferential groove in which the part is located, rotation of the part being prevented by a collar also received in the groove and embracing the separate part. The cylinder may also be cutaway to form a recess in which the other separate part is received.

The invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of a cylinder of a cylinder lock, body and cylinder inserts for housing additional tumblers, and a collar for retaining the body insert, Figure 2 is a perspective view of the body of the lock, Figure 3 is a longitudinal section through the assembled lock, Figure 4 is a cross-section through the lock, Figure 5 shows three views of the cylinder insert, Figure 6 shows two views of the body insert, and Figure 7 shows two views of the collar for retaining the body insert.

Referring to the drawings, a cylinder lock of the pin tumbler type has a tubular body 9, in a cavity in which is rotatably received a cylinder 1. A row of bores extend from the interior surface of the cavity into a projecting portion 9a of the body and in the locked position are in alignment with bores opening through the cylinder into a key slot 2.

Segmented pins 19 are received within the aligned bores and are urged by springs towards the key slot so that one segment of each pin secures the cylinder against rotation. The segments engaging the cylinder are of different lengths to prevent release of the lock by inserting a plain blade. Insertion of an appropriately shaped key 1 8 through the end 2a of the key slot causes the segmented pins to be pressed back against the spring force by suitably varied amounts to bring the meeting ends of the two segments of each pin into the position illustrated, flush with the cylinder periphery to permit its rotation. Pins 1 9 may also be provided for cooperation with the diametrically opposite side of the cylinder.

To provide additional security, the lock is provided with an additional mechanism which acts axially of the cylinder. To accommodate the additional mechanism the cylinder has a circumferential groove 7 adjacent the rear end of the cylinder and dividing the cylinder into a main cylinder portion and a shoulder 8 which may bear a ratchet for operating the latch as the cylinder rotates. For manufacturing convenience, the key slot extends the full length of the cylinder although the key is not long enough to enter the groove 7.

Formed in the edge of the main cylinder portion adjoining the groove is a recess 4, into which opens the key slot 2. Shaped to fit in the recess so as to be fast with the cylinder is an insert 3 having a pair of axially extending, radially aligned bores intersecting a slot forming a continuation of the key slot 2 in the cylinder. The insert 3 has a radial end surface flush with the end surface of the main cylinder portion. Fitting within the groove 7 is an insert 5 having blind bores which align with those in the cylinder insert 3, the body insert 5 being restrained from rotation by a collar 6 also fitting within the channel 7 and embracing the insert 5.

The bores in the insert 5 receive respective springs, 14, 1 5 biasing segmented pins 16, 1 7 received within the aligned bores in the two inserts into positions in which the pin segments 16 engage the forward ends of the bores within the cylinder segment 3 and the segments 17 project from one segment into the other and cooperate with the pins 1 9 to prevent rotation of the cylinder relative to the body. The segments 1 6 are of differing lengths and the key 1 8 suitably shaped at its end so that upon insertion of the key into the slot as shown in Figure 3, the shaped end portion enters the slot extension in the insert 3 and presses the pin segments 16 away from the ends of their bores into a position flush with the radial surface of the insert 3. Lifting of the pins 1 9 takes place at the same time and the lock is released.

A separate insert 3 may be dispensed with and the bores which it contains may be drilled through a suitable radial surface of the main cylinder portion so as to intersect the key slot. In addition, or alternately, the insert 5 may be made in one piece with the collar 6, the shoulder 8 being formed as a separate part secured in place after assembly.

Other modifications may also be made within the scope of the invention, and alternative forms of tumblers or securing means may be provided to cooperate with the side and end of the cylinder.

Reference is made to Greek patent application No. 59432, to the extent that it contains disclosure beyond the foregoing.

Claims (7)

1. A cylinder lock having a body and a cylinder received therein for rotation, the cylinder being secured when locked by tumblers cooperating with the side of the cylinder and at least one additional tumbler located at the rear end of the key slot.

2. A cylinder lock as claimed in claim 1, wherein the or each additional tumbler is a pin tumbler.

3. A cylinder lock as claimed in claim 2, wherein the additional pin tumblers are housed within parts separate from the body and cylinder, one of which parts is fast with the body, and the other part being fast with the cylinder and having a continuation of the key slot opening into the bore or bores for receiving a pin tumbler within that part.

4. A cylinder lock having securing means acting radially of the cylinder and additional securing means acting axially of the cylinder, both said securing means being releasable by formations on a key.

5. A cylinder lock having first pin tumbler means for interlocking the peripheral surface of a lock cylinder and body and second pin tumbler means for interlocking a radial surface of the cylinder and the body.

6. A key having formations along at least one edge and at an end thereof for opening a lock as claimed in any preceding claim.

7. A lock or key therefor substantially as hereinbefore described with reference to and as illustrated in the drawings.