GB2103697A - Key-retaining lock - Google Patents

Abstract

A security lock, for instance for a car park barrier, is key-operated and the key can only be removed when (a) the lock is in a locked state as a result of (b) the barrier being properly engaged with the lock. The boltable element, e.g. a tongue 3 on the barrier, enters a housing. A bolt 6 can engage the tongue to prevent withdrawal, or can free it. A lock mechanism controls movement of the bolt, by operation of a key 5 which can only be removed and inserted when the mechanism is in locked state. When the tongue is not in the casing, a spring-loaded detent 9 prevents rotation of the bolt 6 into its fastening position, thus ensuring that the key is trapped in the lock insertion of tongue 3, e.g. by lowering the barrier, displaces the detent 9 from its blocking position and allows bolt 6 to rotate about axis A...A to lock the tongue and also to allow the key to be freed. <IMAGE>

Description

SPECIFICATION A security lock This invention relates to a security lock of the kind having a lock body, and a boltable element separate from the lock body and which can be engaged with and disengaged from the lock body.

Although the invention is in no way restricted to such use, it is particularly adapted to the securing of barriers such as swingable arms for car-parks and the like.

There are instances where it is desirable that each permitted user of a security lock shall have his own key which can be used for locking and unlocking the security lock when necessary. In particular it is desirable that it shall be impossible for the user to accidentally leave the lock in unlocked condition whilst taking away his key, e.g.

so as to permit free access subsequently to other unauthorised persons.

It is accordingly the object of the present invention to provide an improved form of security lock in which a separable key held by a user can only be removed when the lock mechanism is in locked state, and in which the lock mechanism cannot be put into locked state unless the boltable element has been properly engaged with the lock mechanism.

According to the present invention a security lock comprises a lock body having an opening for introduction and removal of a boltable element, a bolt in the lock body mounted for movement relative to the lock body into a first end position in which it engages with the boltable element and prevents withdrawal of the boltable element, and into a second end position in which it frees the boltable element for withdrawal, a lock mechanism having a removable key and arranged such that by appropriate operation of the inserted key the bolt can be moved to its first and second end positions, the lock mechanism being also such that the key can only be removed from it when the mechanism is in the locked state, and a latch positioned in the body and movable into a first end position in which it is presented in the path of the bolt and prevents the bolt from passing into its first position, and into a second position in which it is remote from the bolt, the latch being urged by loading towards its first position and being positioned in the path of the boltable element such that insertion of the boltable element into the housing causes it to abut the latch and move the latch to its second position.

With such an arrangement, the bolt is only free to move when the boltable element has been fully inserted in the housing, so that the lock mechanism can only be moved to locked state at that time, and accordingly the key can only be removed at that time. When the boltable element is disengaged from the housing, the latch prevents movement of the bolt from unlocked to locked condition, and accordingly the lock mechanism cannot be moved from unlocked to locked condition, and accordingly the key cannot be removed while the security lock as a whole is in anything but fully engaged locked condition.

In a preferred arrangement, the boltable element is a tongue which enters the housing and which has an opening into which a pivotable bolt can be moved for bolting the tongue in locked condition.

The latch may be a member positioned for pivotal movement into and out of the path of the bolt and urged by spring-loading into the position in which it is in the path of the bolt, the pivotal member being situated such that it is abutted by the tongue as the tongue moves toward fully inserted condition.

In a convenient form, the lock mechanism is a cylinder lock which is adapted such that the key can only be removed when the cylinder is in the position of rotation which corresponds to locked condition of the bolt.

In order that the nature of the invention may be readily ascertained, an embodiment of security lock in accordance therewith is hereinafter -particularly described with reference to the figures of the accompanying drawing, wherein: Fig. 1 is a side elevation of the security lock in locked position; Fig. 2 is a similar view of the lock in open position.

The security lock comprises a housing 1 which is generally of strong and non-forcible construction, e.g. of steel and which has a removable cover plate (not shown) to provide access to the interior. In these drawings, the cover plate has been removed. When in use, the cover would be secured in place by means ensuring difficulty or impossibility of access to an unauthorised person.

In the position as illustrated in the drawings, the housing is arranged for cooperation with a vertically movable barrier, e.g. a barrier arm across a roadway for a car-park, but it wili be appreciated that the housing can also be positioned for a horizontally movable barrier item.

The housing has an opening 2 at its upper end for introduction and removal of a tongue 3 on the barrier arm (not shown). Within the housing there is mounted a lock mechanism 4 which is accessible to a key 5 projecting externally of the housing 1. The lock mechanism has a bolt element 6 which is movable, about an axis parallel to the plane of the drawing, into a first end position in which the longitudinal dimension of the element is parallel to the plane of the drawing, and it can be swung upwardly through 900 about an axis A-A into a second end position in which the longitudinal dimension of the element projects at a right angle from the plane of the drawing. The first position is seen in Fig. 2 of the drawing, and the second position is seen in Fig. 1 of the drawing.The bolt element 6 is controlled by lock mechanism so that, whereas the bolt element can be moved into each of its end positions by operation of the key 5, the bolt element cannot be shifted out of the respective end positions by force applied to the element itself.

The tongue 3 has an opening 7 which can receive the bolt element 6 engaged through it, and which is elongated sufficiently to permit the angular movement of the bolt element 6 through 900 between its first and second positions.

Also within the housing 1 there is mounted a support 8 on which a latch 9 is pivoted for movement about a pivot 1 0. A tension spring 11 is connected at one end to the latch 9 and at the other end to the support 8, and tends to urge the latch 9 to a raised position as shown in Fig. 2.

The key 5 is engaged into the barrel of a cylinder lock mechanism "L" which is of such construction that the key cannot be removed, axially of the cylinder, unless the lock is in locked condition, i.e. with the bolt element 6 horizontal as seen in Fig. 2.

The operation is as follows: It is assumed that the whole of the housing 1 and its contents are mounted at one side of a road-way opening which is to be closed by a releasable vertically-swingable barrier arm. The tongue 3 is secured on the end of the arm, and can pass substantially vertically into and out of the top opening 2 of the housing.

Assuming that the barrier has been opened, the key 5 is trapped in the lock mechanism L and cannot be removed. The barrier arm is then swung down, e.g. after passage of a vehicle, and the tongue 3 passes through the opening 2 of the housing and is forced slightly beyond its rest position into the position seen in Fig. 1. In this position, the tongue has abutted the latch 9 and pushed it downwardly against the loading of its spring 11.

The tongue 3 is held in this position e.g. by its own weight under gravity, or manually. In this position of the tongue 3, the opening 7 is presented opposite to the bolt 6. The bolt 6 can accordingly be moved from its vertical position (lock open) up to its horizontal position (lock closed) by operation of the key 5. The tongue 3 is then permitted to rise slightly under the action of the spring 11. In its horizontal position the bolt 6 prevents removal of the tongue 3 upwardly, and accordingly the barrier is locked in closed condition. As the cylinder lock is now in closed condition, the key 5 can be removed by the user.

The parts are then in the state shown in Fig. 1.

If it is subsequently desired to open the barrier, the key 5 is inserted in the lock and is rotated to cause the bolt 6 to move through 900 from its raised position of Fig. 1 to its lowered position of Fig. 2, the tongue 3 being slightly depressed. This disengages the bolt 6 from the opening 7 of the tongue 3, so that the tongue can then rise and pass entirely out of the housing 1, to permit the barrier arm to be raised. The upward movement of the tongue 3 permits the latch 9 to rise, under the loading of its spring 11, so that the latch 9 then passes into the horizontal position seen in Fig. 2, in which it is presented across the front of the bolt 6, thereby preventing the bolt 6 from moving back again to its lowered position. As the bolt 6 cannot move back to open condition of the cylinder lock, the key 5 remains trapped in the cylinder lock mechanism. Thus the user is made aware that his key is still left in the lock, and he must ensure that the apparatus is re-locked (by swinging down the barrier arm again) before he can rotate the cylinder to locked condition and thereby release his key for axial withdrawal. Thus, it is impossible for a user to both retain his key and leave the apparatus in unlocked state. The user must return the apparatus to the locked state (and only with the tongue in fully lowered position) before the key can be removed and taken away.

Claims (5)

1. A security lock comprising a lock body having an opening for introduction and removal of a boltable element, a bolt in the lock body mounted for movement relative to the lock body into a first end position in which it engages with the boltable element and prevents withdrawal of the boltable element, and into a second end position in which it frees the boltable element for withdrawal, a lock mechanism having a removable key and arranged such that by appropriate operation of the inserted key the bolt can be moved to its first and second end positions, the lock mechanism being also such that the key can only be removed from it when the mechanism is in the locked state, and a latch positioned in the body and movable into a first end position in which it is presented in the path of the bolt and prevents the bolt from passing into its first position, and into a second position in which it is remote from the bolt, the latch being urged by loading towards its first position and being positioned in the path of the boltable element such that insertion of the boltable element into the housing causes it to abut the latch and move the latch to its second position.

2. A security lock, as claimed in Claim 1, wherein the boltable element is a tongue which enters the housing, and wherein the bolt is pivotable, the tongue having an opening into which the bolt can move by pivoting for bolting the tongue in locked condition.

3. A security lock, as claimed in either of Claims 1 and 2, wherein the latch is pivotable into and out of the path of the bolt, and wherein the loading of the latch is spring loading which urges the latch into a position in which it is in the path of the bolt, the latch being positioned such that it is abutted and moved against its spring loading by the tongue as the tongue moves towards fully inserted condition.

4. A security lock, as claimed in any one of Claims 1 to 3, wherein the lock mechanism is a cylinder lock which is constructed such that the key thereof can only be removed when the cylinder is in the position of rotation which corresponds to the locked condition of the bolt.

5. A security lock substantially as described herein with reference to the accompanying drawings.