GB2075108A - Cylinder lock and key - Google Patents

Abstract

A cylinder lock has a key with a head 41 and a spiral shank 42 extending therefrom, the shank having a series of longitudinal slots 431, 432 etc for cooperation with complementary wards 231, 232 etc of varying diameter on the inside of a rotatable cylinder. As shown, bush 30 in anchored in the lock body by a bar 15 and rotatably supports skirt 24 of the cylinder. When locked, ball 35 is urged by spring 36 into aligned holes in the bush 30 and skirt 24 to prevent rotation. The bush 30 provides keyway 32 into which the shank 24 must be screwed. When properly inverted the grooves 431 etc are aligned with wards 231 and pushing the key engages them. A portion of shank 24 engages ball 35 to force it far enough out to allow the cylinder to be rotated by the key, thus presenting flats 26 to locking balls 13. This allows them to move inwardly and so release shackle 12. <IMAGE>

Description

SPECIFICATION A cylinder lock TECHNICAL FIELD This invention relates to cylinder locks.

BACKGROUND ART In traditional locks which have a cylinder turned by the insertion of a key through a keyhole, the keyway is flat and straight and within this keyway extend wards. When a key with a contoured profile on one edge is inserted into the keyway from the keyhole, the wards will be contacted by these undulations and, if the correct key is inserted in the lock, then the wards will all be in such a position as to enable the cylinder to be turned. With traditional locks of this type, it is comparatively easy to unlock the cylinder by using a key which in not precisely identical but similar to the correct key, or the cylinder may be turned by the insertion into the keyway of wires or hooks. Because the keyway is straight, the wards are easily seen from the keyhole and, as a result, the shape of the correct key to turn the cylinder may be observed by an unauthorised person.

A further disadvantage with conventional cylinder locks is that the wards are normally held in their locking position by the use of springs and the key moves the wards against the action of the springs to enable rotation of the cylinder. After some use, the locks may become rusty and dirty and the springs may fail in their intended purpose, thus reducing the life of the lock.

Still further, traditional locks are complicated in their construction which means that these are difficult to assemble and to manufacture and which also means that the cost of production is high.

It is the main object of this invention to provide a cylinder lock which obviates the above defects in that the lock is more secure against unauthorised unlocking without the use of the correct key and also that the use of spring loaded wards is obviated. Thus the life of the lock is increased.

DISCLOSURE OF THE INVENTION According to the present invention there is provided a cylinder lock having a body with a bore therein, a cylinder located within the bore for rotation therein, a cylinder located within the bore for rotation therein, a bush located within the bore and fixed against rotation in the bore and a key for operation of the lock, characterised in that the key comprises a head and a spiral shank extending from the head, said shank having a series of longitudinally extending slots and the cylinder having a series of projections complementary to the slots on the shank of the key, the complementary slots and projections being engageable on the shank of the key being inserted through the bush to turn the cylinder in the body.

BRIEF DESCRIPTION OF DRAWINGS Figure 1 is an expioded perspective view of a cylinder lock constructed in accordance with the invention; Figure 2 is a longitudinal cross-sectional view of the assembled lock of Fig. 1 with the key in position; Figure 3 is a fragmentary cross-sectional view on the line Ill-Ill of Fig. 2; Figure 4 is a view of a ball which prevents or permits rotation between the cylinder and bush; and Figure 5 is an end view of the cylinder.

MODE FOR CARRYING OUT THE INVENTION Referring now to the drawings, the cylinder lock according to the invention includes a body 10, a cylinder 20, a bush 30 and a key 40.

The key 40 includes a head 41 which may be gripped in the figures by the user of the key. Extending from the head 41 is a spiral shank 42 having, towards the free end thereof, longitudinally extending slots 43 (there may be up to ten such slots numbered 431 to 440 inclusive). These slots 431 to 440 lie on the outer surface of the spiral shank 42 and, as will be seen from Fig. 3, there are six of these slots in this embodiment. On the other hand, there may well be ten such slots or any other number dependent on the design. All of these slots are of differing dimensions.

The bush 30 has a keyhole entrance 31 which leads to a keyway 32 defined by a plurality of internal apertures. The spiral shank 42 of the key 40, in being entered through the keyhole 31, is rotated so that the spiral shank finds its way through the keyway to the other end of the bush. In the wall of the bush 30 is a recess with a hole 38. This hole receives a ball 35 (see Fig. 4) urged inwardly by a spring 36 held in position by a screw 37.

The cylinder 20 is formed with a cylindrical portion 24 which enters the other end 34 of the bush 30. On the inner surface of the cylindrical portion 24 is a series of projections 23, in this case these projections being in the form of longitudinally extending rods indicated by the reference 231 and 240 inclusive. There are as many rods as there are slots in the spiral shank of the key i.e. six as shown in Fig. 3 or there may be up to ten such rods.

These rods are of differing diameters so as each to be received in a complementary slot in the spiral shank of the key. In the wall of the cylinder 24 is a hole 28 which, when the cylinder lock is in the secure condition, is in register with the hole 38 in the bush so that the ball 35 will be partly in the hole 28 and partly in the hole 38 so as to prevent rotation of the cylinder within the bush.

Integral with the cylindrical portion 24 is a head portion 241 having a part 21 which has two convex portions 27 and two flat portions 26 the purpose of which will be explained later.

The body 10 has a longitudinally extending bore 11 therein, one end of the bore being open to receive the cylinder 20, the bush 30 and also to receive the key when it is used.

The bore 11 also has a closed other end. At this closed end there are formed two blind holes 1 6 which receive the arms of a hook 1 2 each said arm having a recess 121 therein. A ball 1 3 lies in an aperture 14 which communicates between each blind hole 1 6 and the bore 11 so as to enable the hook 1 2 to be secured in position or released as desired. A pin 1 5 enters a hole 151 in the wall of the body 10 so as to retain the bush within the bore 11 against rotation.

To assemble the cylinder lock, the cylinder 20 is inserted in the bore 11 and the bush is inserted so that the cylinder portion 24 enters the end 34 of the bush. The body 10, cylinder 20 and bush 30 are retained as a unit by the pin 15.

The hook 1 2 is retained in its locked position by balls 13 entering the recesses 121 as shown in full lines in Fig. 2. The cylinder lock is then in a secured condition.

To unlock the hook 12, the spiral shank 42 of the key 40 is inserted through the keyhole 31 and the spiral shank is moved along the keyway 32 by a rotating movement of the key until such time as the free end of the key reaches the rods 23. Because the keyhole ends of the rods are disposed in a spiral having the same configuration as the spiral shank of the key, the respective ends of the rods and the slots are presented to each other simultaneously. Then, by a longitudinal movement of the key, the slots are engaged with the rods, the keyway 32 in the bush being so dimensioned as to permit this limited longitudinal movement of the key. This longitudinal movement of the key also moves the ball 35 outwardly so as to release the ball from the hole 28 in the wall of the cylinder and permit the cylinder to rotate within the bush.Then, by rotation of the head of the key, the cylinder will be rotated and the convex portions 27 of the head of the cylinder which, in the secure position, were holding the balls 1 3 within recesses 1 21 to secure the hook, will be replaced by the flats 36 of the head of the cylinder, thereby enabling the balls 13 to move inwardly (as shown in dotted lines in Fig. 2) and the hook 1 2 to be removed.

To resecure the hook within the body 10, the arms of the hook are reinserted in the holes 1 6 and the key is turned so that the convex portions 27 of the head of the cylinder move the balls 1 3 outwardly to lie in the recesses 121. This movement brings the holes 28 and 38 into register so that the ball 35 now moves inwardly and, when the key is withdrawn by longitudinal and then rotational movement to remove the spiral shank from the bush, the cylinder lock is again secure.

Because the projections on the inner surface of the cylinder are in the form of rods (preferably steel rods) the number and diameters of these rods may vary greatly. They will, of course, be consistent with the number and dimensions of the slots in the spiral shank of the key to operate that particular lock. In this part of the mechanism, no springs are involved which might deteriorate with the passage of time and, therefore, the lock has a very long life and is unlikely to be affected by the environment in which the lock is placed.

Claims (8)

1. A cylinder lock having a body with a bore therein, a cylinder located within the bore for rotation therein, a bush located within the bore and fixed against rotation in the bore and a key for operation of the lock, characterised in that the key comprises a head and a spiral shank extending from the head, said shank having a series of longitudinally extending slots and the cylinder having a series of projections complementary to the slots on the shank of the key, the complementary slots and projections being engageable on the shank of the key being inserted through the bush to turn the cylinder in the body.

2. A cylinder lock as claimed in Claim 1, in which the bush is provided with a keyway to receive the spiral shank of the key, the keyway permitting limited longitudinal movement of the shank therein without turning of the shank to enable the slots on the shank to engage the projections of the cylinder.

3. A cylinder lock as claimed in Claim 2 in which one end of the bush defines a keyhole, the bush having a plurality of internal apertures which define the keyway through which the spiral shank of the key passes prior to engagement of the complementary slots and projections.

4. A cylinder lock as claimed in any one of the preceding claims, in which the bush and cylinder are each provided with a hole in the walls thereof, said holes being in register when the lock is in a secure condition and a spring loaded ball within said registering holes to prevent rotation of the cylinder in the bush, said ball being movable against the spring action by engagement of the key to enable rotation of the cylinder in the bush.

5. A cylinder lock as claimed in any one of the preceding claims in which the projec tions are in the form of a series of rods extending longitudinally and projecting from the internal surface of the cylinder, the rods being of differing diameters.

6. A cylinder lock as claimed in Claim 5, in which the keyhole ends of the rods are disposed in a spiral array so that the mating ends of the slots engage their respective rods simultaneously.

7. A cylinder lock as claimed in any one of the preceding claims, in which the body is provided with two blind holes each to receive one arm of a hook, each arm having a recess into which projects a ball to lock the hook in the body, the balls being held in their locking position by engagement with convex portions on the head of the cylinder, said head also having flats which permit the balls to move out of the recesses and the hook to be removed on the cylinder being rotated by the key.

8. A cylinder lock substantially as herein described with reference to the accompanying drawings.