Claims:
I claim
1. A security bolt comprising a bolt longitudinally slidable between projecting and withdrawn positions, a guide element mounted on the bolt and projecting normally to the axis of movement of the bolt, said guide element including a seating, a guide member having a slot positioned parallel to the axis of movement of the bolt and through which slot the guide element protrudes, a knob rotatably mounted on the guide member and having in its face adjacent to the guide member a scroll groove in which the free end of the guide element engages such that upon rotation of the knob the bolt is cause to slide longitudinally, and a stop member carried by the rotatable knob and spaced radially from the axis of rotation of the knob, said stop member being shiftable parallel to the axis of the knob for engagement into and withdrawal from the seating of the guide element, thereby to permit locking of the knob releasably against rotation.
2. A security bolt, as claimed in claim 1, wherein said scroll groove extends 360° about the axis of rotation of the knob, and wherein said stop member is positioned on a radius corresponding to both end positions of the guide element in the scroll groove, whereby said stop can lodge in the slot of the guide member at each end of the rotational movement of the knob.
3. A security bolt, as claimed in claim 2, comprising means for spring-urging said stop member towards entering its seating in said guide element.
Description:
This invention relates to bolts for providing security to doors and windows against outside intruders.
The object of the invention is to provide an improved construction of security bolt which cannot be forced from the exterior of a door or window structure on which it is applied, and which thus cannot be unauthorizedly opened except by shattering of the structure and thereby tending to attract attention.
According to the present invention, a security bolt comprises a bolt longitudinally slidable between projecting and withdrawn positions, i.e. locking and nonlocking conditions, a guide element projecting normally to the axis of movement of the bolt, a guide member for mounting on the structure and having a slot positioned parallel to the axis of movement of the bolt, through which slot the guide element protrudes, and a knob rotatably mounted on the guide member and having in its face adjacent to the guide member a scroll groove in which the free end of the guide element engages, such that upon rotation of the knob, the bolt is caused to slide longitudinally.
Due to the provision of a scroll groove and a guide element to engage therein, no kind of manipulation of the bolt itself can free the bolt to slide longitudinally, and the security bolt is accordingly proof against the insertion of knife blades, celluloid sheets and like instruments between the door or window and its frame.
To provide a further security against unauthorized operation of the bolt from the exterior of the door or window, the rotatable knob may carry a stop member which is spaced radially from the axis of rotation of the knob and which is shiftable parallel to the axis of the knob for engagement into and withdrawal from a seating in the guide member, which may be the slot of the guide member, thereby to permit releasable locking of the knob against rotation.
In a preferred form, the scroll groove extends 360° about the axis of rotation of the knob, and the stop member is positioned on a radius corresponding to both end positions of the guide element in the scroll groove, whereby said stop can lodge in the slot of the guide member at each end of the rotational movement of the knob, i.e. in the locked and unlocked conditions of the bolt.
Preferably the stop member is spring-urged towards entering the seating, thereby to pass into position automatically as soon as the knob has been appropriately rotated.
The bolt itself may be slidable through a faceplate of conventional nature secured, e.g. as by wood screws, on the edge face of the door or window or a frame therefor. However, in a preferred modification, the bolt is slidable in a housing and a fastening means is engaged with the guide member and with the housing to lock the housing against movement along the axis of the bolt, i.e. to secure a simple cylindrical housing in a cylindrical bore in the door or window structure.
In order that the nature of the invention may be readily ascertained, two embodiments of security bolt in accordance therewith are hereinafter particularly described with reference to the figures of the accompanying drawings, wherein:
FIG. 1 is a front elevation of a first embodiment of bolt, in position on a door;
FIG. 2 is a horizontal section taken on the line II-II of FIG. 1;
FIG. 3 is an elevation of a guide disc member for mounting on the door face;
FIG. 4 is an elevation of a knob, to show a scroll groove;
FIG. 5 is a front elevation of a second embodiment of bolt, in position on a door;
FIG. 6 is a horizontal section taken on the line VI-VI of FIG. 5;
FIG. 7 is an elevation of a guide disc member for mounting on a door face.
Referring to FIGS. 1 to 4, the security bolt comprises a cylindrical bolt member 1 which is slidably housed in a cylindrical passage in a door or window stile 2, and which can slide longitudinally through a conventional faceplate 1a between an operative position as shown in broken line, and an inoperative position as shown in full line. Near one end, the bolt member 1 is drilled and tapped radially at right angles to its longitudinal centerline to receive a steel guide pin element 3 threaded into it. The door or window stile 2 has a slot 4 parallel with the axis of the bolt member 1, for movement of the guide pin 3 as the bolt member is moved longitudinally. It will be appreciated that, instead of being housed in a cylindrical passage bored in the door or window stile 2, the bolt member 1 could be mounted slidably within a cylindrical metal housing received in the door or window stile, said housing being similarly slotted as at 4. A circular guide disc 5 is secured to the inner face of the door or window stile by means of a number of screws 6, and the central axis of the guide disc 5 passes through the central longitudinal axis of the bolt member 1.
The guide disc 5 has a radial slot 7 coinciding with the slot 4 in the stile, and the guide pin 3 protrudes through the slot 7.
A knob 8 is rotatably mounted on the disc 5 by means of a central threaded and flanged spindle 9, and the knob 8 is recessed at 10 at its underside to receive the guide disc 5. Preferably a small clearance is left between the knob 8 and the stile 2 to permit the knob to be rotated without undue friction.
In the recessed face of the knob 8 there is cut a scroll groove 11, said groove commencing near to the axis of rotation of the knob and extending for 360° round the axis of the knob to a point further radially outwards of its commencement.
The free end of the guide pin 3 protrudes through the slot of the disc 5 and enters into the scroll groove 11.
As the knob 8 is rotated, the guide pin is shifted by abutment with the sidewalls of the scroll groove, and the bolt member 1 is caused to protrude, or is withdrawn, according to the direction of rotation of the knob.
A stop member 12, provided with a knob 13 for manual operation, is positioned with its axis of longitudinal movement on a radius of the guide disc 5 passing through the positions occupied in the scroll groove 11 at each end of travel of the pin 3 therein. The stop member carries at its end a cylindrical stud 14 in a bore 15. At each end of rotational travel of the knob 8, the stud 14 can enter into the slot 7 of the guide disc 5, serving as a seating, under the action of a loading spring 16. Accordingly, the stud 14 automatically enters its seating at each end of the rotational travel, and thereby locks the knob against further rotation until such time as the stop member has been retracted, against its spring-loading, by pulling the knob 13 outwardly.
Accordingly, the bolt 1 is deadlocked against movement out of both of its end positions by abutment of the guide pin 3 against the sidewalls of the scroll groove, and the knob 8 cannot be rotated unless and until the stud 14 has been manually withdrawn against its spring-loading.
It will be appreciated that such a bolt cannot be released, by an unauthorized person, by acting on the bolt member 1 itself, or by any tampering operation carried out from that face of the door remote from the knob 8. The bolt could in fact only be released, unauthorizedly, by making a hole through the fabric of the door large enough to pass the hand through for manipulating the stop member knob 13 and the rotational knob 8, and it is anticipated that the disturbance which would be entailed would tend to attract attention so that the function of the security bolt would be fulfilled.
The security bolt may be made to any convenient size, and could be used as a catch for a cabinet door, or as a high security lock on entrance doors or gates to a building. The simplicity of construction and design permits the security bolt to be manufactured in inexpensive and modern materials.
Referring now to FIGS. 5 to 7, there are seen similar views of a second embodiment of security bolt. In this embodiment, the bolt housing 17 in which the bolt 1 is longitudinally slidable, is a simple cylindrical body with a bevelled flange 18 which is driven into the material of the door or window stile to locate the housing firmly in position. This construction avoids the need to provide a conventional faceplate on the exposed edge face 19 of the door. To retain the housing in its position, the guide disc 20 mounted on the inside face of the door receives a countersunk threaded screw 21 which is threadedly engaged also into the housing 17, so that the housing cannot be pulled out longitudinally until the screw 21 has been withdrawn. The action of the remainder of this embodiment of security bolt is the same as has been described above in relation to the first embodiment.