GB2246162A - Locks - Google Patents

Abstract

A key-operated lock (as shown, a padlock) has a keyhole cover assembly comprising a pair of shutter elements 8, 9 biased towards each other by an encircling tension spring 10 such as normally to close the entrance for the key to the lock. The shutter elements are however displaceable apart against the spring bias when the tip of a key is pressed in, and the assembly is rotatable as a whole together with the key when the latter is inserted and turned in the lock. Components 8, 9, 10 are retained by a base plate 11 secured to lock casing (1, Figure 1). Element 8 is a truncated disc with a lug 8A and element 9 is a slide with a pin 14 which is withdrawn from detention 22 in base plate 11 when the key is inserted to free the assembly for rotation. <IMAGE>

Description

Locks The present invention relates to key-operated locks and more particularly to an improved keyhole cover assembly therefor.

With some locks, keyhole covers - or covered escutcheons are provided for purely decorative purposes. However, in many conditions of use a keyhole cover becomes a practical necessity to prevent dirt or other extraneous matter entering the lock mechanism. As a typical example there can be quoted the use of a padlock to sure a vehicle tailgate, which will constantly be exposed to dirt thrown up from the road surface.

A common form of keyhole cover comprises a shutter borne on a pin located above the keyhole so as normally to swing down in front of the keyhole under its own weight. This simple arrangement can only effectively be used with the lock in a fixed orientation, however, and cannot provide a properly weatherproof seal. Versions are also known with a similarly pivoted shutter but where the pivot is spring loaded so that the shutter is retained frictionally with a tighter fit in its keyhole closing position - or in any other position to which it is set. A disadvantage, however, is that the shutter must be manually displaced away from its closing position before the key can be inserted, and the user must also remember to manually return the shutter to that position after use or else its presence will be nugatory.

It is therefore an aim of the present invention to provide a keyhole cover assembly which can overcome these drawbacks of the prior art and accordingly the invention resides in a key-operated lock provided with a keyhole cover assembly comprising a pair of shutter element spring biased towards each other such as normally to close the entrance for the key but being displaceable apart against the spring bias to permit insertion of the key and being rotatable as a whole together with the key as the latter is turned in the lock. In this way, the spring biasing of the shutter elements can ensure that the assembly is automatically returned to its keyhole closing condition whenever the key is withdrawn.At the same time, the turning of the shutter elements together with the key means that the shutter elements need only be moved apart by a distance equal to the thickness of the key, which makes for a compact assembly, and the spring biasing will not impose a load resisting turning of the key - which might otherwise be considerable in the case of a flat key for a cylinder lock.

Preferably, the shutter elements are configured, such as with a chamfered surface at the engaging edge of at least one of them, so as to be displaced apart by the action of pressing the key tip against the assembly in the direction of insertion into the lock.

In a preferred embodiment, the shutter elements collectively define a generally disc-like assembly journalled in a housing and are biased towards each other by an annular spring held in tension around a circumference of the assembly.

One of the shutter elements may also comprise a projecting portion which engages in a housing when the assembly is in its closing condition thereby to resist rotation of the shutter elements away from a predetermined position in relation to the keyhole, but which frees the shutter elements for rotation when displaced apart as aforesaid.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a vertical section through a padlock equipped with a keyhole cover assembly in accordance with a preferred embodiment of the invention, shown unlocked but with the key inserted; Figure 2 is a view of the cover assembly in the sense of the arrow II in Figure 1, with the key withdrawn; Figure 3 is a section on the line III-III of Figure 2; Figures 4 and 5 are separate views of the two shutter elements of the cover assembly; and Figures 6 and 7 are views of the cover assembly similar to Figure 2 but with the key just inserted and turned respectively.

With reference to Figure 1, the illustrated padlock has a casing 1 and shackle 2, shown in its unlocked condition.

Locking and unlocking of the shackle is controlled by a pin cylinder unit 3, the rotatable plug of which carries a cam 4 to thrust out a pair of balls 5 into seats 6 in the arms of the shackle when the latter are slid into the casing. The cylinder plug is in this respect turned through approximately 90 by a flat key 7 inserted through the base of the lock, it being necessary to turn the key back to the same insertion position before it can be withdrawn. As thus far described, the construction and operation of the lock is essentially conventional.

However, it comprises in addition a novel assembly for closing the key entrance to the cylinder plug as will now be described with reference also to Figures 2-7.

More particularly, the keyhole cover assembly comprises a pair of shutter elements 8, 9 and an encircling spring 10, all retained by a base plate 11 secured to the lock casing l. The element 8 is in the form of a truncated disc borne rotatably within a circular recess 12 in the base plate 11. A peripheral lug 8A on the outside of this element runs in an arcuate groove 12A in the base plate to set the limits of its permissible rotation. The element 9 is in the form of a slide borne between the arms 13 of the disc 8, and has an integral pin 14 extending through a groove 15 in the disc for a purpose to be described hereafter. The disc, slide and base plate 8,9,11 are all preferably moulded from a self-lubricating plastics material such as polypropylene.The disc and slide 8,9 are formed with respective semi-annular ledges 16,17 around which is seated the spring 10. The latter is preferably made of stainless steel and is similar in form to the kind commonly used in oil seals, comprising a wire coil tapered at one end and locked into the other end to form a ring, and is held in tension around the assembly of disc 8 and slide 9. Accordingly, this spring normally acts to hold the shutter elements together as shown in Figures 2 and 3, where their edges 18 and 19 engage to cover the keyhole and exclude dirt or other extraneous matter from entering the cylinder plug.

Clearly, when the key 7 is to be inserted into the lock the elements 8 and 9 must be displaced apart to pass the key. To facilitate this, the edge 18 of the disc 8 is provided with a semi-circular chamfered surface 20 in the region of the keyhole and the facing portion of the edge 19 of the slide is thickened where indicated at 21. The surface 20 therefore acts as a lead-in portion to guide the tip of the key as it is offered to the assembly, and as the key is pressed in it is slid laterally by this surface against the thickened edge 19 of the slide 9 to displace the slide from its Figure 3 to its Figure 1 position against the bias of the spring 10 and to align the key tip correctly with the entrance to the cylinder plug. This condition is also seen in Figure 6.As the inserted key is then turned, it turns with it the assembly of disc 8, slide 9 and spring 10 to the unlocking condition seen in Figure 7, in which the lug 8A on element 8 passes to the opposite end of the groove 12A. The key returns the assembly to its original rotary position of Figure 6 when the key itself is turned back. When the key is withdrawn, the slide 9 automatically returns to its closing position against the disc 8 under the bias of the spring 10. No additional manipulation of the keyhole cover assembly is therefore required to open and close it, beyond the normal action of inserting and withdrawing the key.

In the normal, closing condition of the assembly as shown in Figure 2, the end of the pin 14 of the the slide 9 extends from the end of the groove 15 of the disc 8 and into a detention 22 formed in the base plate 11, thereby to resist rotation of the disc and slide away from its position of alignment with the keyhole. When the key is inserted and the slide 9 displaced with respect to the disc 8, however, the pin 14 is withdrawn from the detention 22 (as shown in Figure 6) and the assembly is freed for rotation.

Claims (5)

1. A key-operated lock provided with a keyhole cover assembly comprising a pair of shutter elements spring biased towards each other such as normally to close the entrance for the key but being displaceable apart against the spring bias to permit insertion of the key and being rotatable as a whole together with the key as the latter is turned in the lock.

2. A lock according to claim 1 wherein the shutter elements are configured so as to be displaced apart by the action of pressing the key tip against the assembly in the direction of insertion into the lock.

3. A lock according to claim 1 or claim 2 wherein the shutter elements collectively define a generally disc-like assembly journalled in a housing and are biased towards each other by an annular spring held in tension around a circumference of the assembly.

4. A lock according to any preceding claim wherein one of the shutter elements also comprises a projecting portion which engages in a housing when the assembly is in its closing condition thereby to resist rotation of the shutter elements away from a predetermined position in relation to the keyhole, but which frees the shutter elements for rotation when displaced apart as aforesaid.

5. A key-operated lock provided with a keyhole cover assembly substantially as hereinbefore described with reference to the accompanying drawings.