Technical Field

The present invention relates to a reusable evacuation cap or reusable security cap, which is preferably made of a plastics material and intended as a door fitting.

Such security caps are intended to safeguard the knob, handle or twist-grip of the lock of an emergency exit door or the like. The intention of such caps is to deter unauthorized and unnecessary exit through an emergency exit at normal times, but to allow the exit to be used in times of an emergency, such as in the event of a fire or like hazard. Background Prior Art

Prior art security caps of this kind are normally made of a hard transparent plastics material and are provided with fastener means with which the cap is fitted over the knob, with the knob visible within the cap. In order to reach the knob or like handle, it is necessary to break off the cap, at a milled weakening provided to this end. Part of the cap is left in the fastener means and must be removed with the aid of a screw driver or like tool. The cap is thus destroyed and cannot be reused, which means that a new cap must be fitted.

Other known security caps of this kind presents an aperture through which a twist-grip or handle protrudes. In order to open the door to which the cap is fitted, it is necessary to turn the handle with a force sufficient to break the cap. As with the previously mentioned security cap, it is necessary to remove the residual part of the cap and fit a new complete cap. Another example of lock guards which must be destroyed in order to reach a lock - in this case an espagnolette lock is described and illustrated in SE-B-360702 (Hammer et al) .

DE-A-3 026 546, US-A-4 267 549 and US-A-4 280 120 describe further examples of the state of this art, of which the US- publication discloses various embodiments of protective covers and fire covers.

One disadvantage with these known security caps or covers is that when broken they leave sharp edges which are liable to injure the person breaking the cap or turning the knob or like handle. Object of the Invention

The object of the present invention is to provide a security cap or cover of the aforedescribed kind with which the aforesaid drawbacks, and other drawbacks, inherent with known security caps are avoided, and which is of improved constructions for more economical use.

Disclosure of the Invention

In its widest aspect a security cap according to the inven¬ tion is mainly characterized in that it includes an inner perman¬ ently fixed part and an outer detachable part, and in that the outer part is joined to the inner part by means of shear pins which cannot be removed without fracturing, wherewith the two parts of the cap remain undamaged and can be reused after fitting new shear pins.

When the security cap is broken loose, only the shear pins are damaged. These pins can be replaced readily at but small cost, preferably without requiring the use of the tool.

In accordance with one preferred embodiment of the invention, each shear pin is provided with a fracture notch or like weaken¬ ing, which is preferably located along a respective pin in the plane between the inner and the outer cap parts.

The shear pins are suitably provided with outwardly projec¬ ting portions which are intended to spring in towards the centre line of respective pins.

The outer cap part is conveniently connected to the inner cap part by a line from which the cap hangs subsequent to being broken loose.

This line can be attached in various ways, but is prefer¬ ably accommodated within the cap when the cap is in place.

When the outer part of the cap is broken loose from the inner part, it hangs on the line and can readily be replaced subsequent to fitting new shear pins.

The configuration given to the reusable security cap is contingent on the design of the lock to which it is fitted. In accordance with one alternative embodiment, the cap is pro¬ vided with a slot or like aperture for receiving an outwardly projecting handle or twist-grip, which serves as a lever when removing the outer cap part by shearing the aforesaid pins. The inner part of the security cap, or mounting part there¬ of, can be mounted on existing anti-twist devices, so as to be resistantto twisting, and conforms to accepted standards.

The outer, removable part of the security cap is preferably made of a transparent plastics material and is coated at least partially with a luminous paint.

The invention will now be described in greater detail with reference to a number of embodiments thereof illustrated in the accompanying drawings. Brief Description of the Drawings Figure 1 is a perspective view illustrating part of a door as having fitted thereto a security cap according to the inven¬ tion.

Figure 2 is a sectional view taken on the line II-II in Figure 1 and illustrates a flange connection between the per- manently fixed part of the cap and its detachable part, and shows the two cap parts joined together by means of shear pins.

Figure 3 is a sectional view corresponding to Figure 2, subsequent to breaking loose the outer part of the security cap. Figure 4 is a perspective view showing the outer part of the security cap hanging from a line, subsequent to breaking the outer part loose from the inner part.

Figure 5 is a perspective view of a modified embodiment of the security cap intended for co-action with a handle or twist-grip projecting from the cap. Description of Preferred Embodiments In Figures 1 - 4 the reference 1 identifies an emergency exit door, which is held locked by means of a cylinder lock 2 mounted in an escutcheon 3.

The lock mechanism (not shown) of the cylinder lock 2 is turned with the aid of a twist-grip or like knob 4, which is covered by a reusable security cap of transparent plastics material, shown generally at 5.

In the case of an emergency, the security cap can be opened, the twist-grip 4 turned, and the door opened, even by someone not in the possession of the appropriate key. The security cap 5 comprises an inner part 6, which is per¬ manently secured to the door with the aid of screws 10, and an outer part 7, which in the illustrated embodiment is joined to the inner part 6 by means σf three shear pins 8 and which can be broken loose from the inner part, by shearing said pins. The pins 8 cannot be removed without fracturing-, and hence the two parts 6 and 7 of the security cap remain undamaged and can be reused by joining the same together with fresh shear pins.

As shown in Figure 2, each shear pin 8 comprises a head 8a, a stem 8b, and sprung legs 8c provided at the ends thereof with barbs 8d.

The shear pins are passed through mutually opposite holes 6c, 7c, provided in mutually abutting mounting flanges 6a, 7a on respective cap parts 6 and 7.

The shear pin 8 is provided with a fracture notch or like weakening 8-e which when the pin is in place lies in the region of the abutment plane of the flanges 6a, 7a.

When force is applied to the outer cap part 7 in order to

detach it from the inner cap part 6, the shear pins fracture at the location of the respective fracture notches, in the manner illustrated in Figure 3. The outer cap part 7 is connected to the inner cap part 6 by means of a line 9, such that when the outer part is broken loose it will hang from the line 9 and can be replaced over the twist-grip 4, subse¬ quent tσ fitting new shear pins 8.

The line can be attached to the two cap parts 6 and 7, but is most suitably accommodated within the outer cap part 7 with said part positioned over the twist-grip or like handle 4.

Figure 5 illustrates a modified embodiment in which the outer cap part is provided with an aperture 7b through which there projects a handle or like turning device 10 for operating the lock mechanism.

The security cover can be broken loose, by pressing down on the handle 11, whereupon the pins 8 shear in the afore- described manner.

The inner and outer parts 6, 7 of this embodiment are also connected by a line 9. Industrial Application

A security cap or cover according to the invention can be used in conjunction with various type of lock arrangements, with the inner cap part being given a commensurate configuration and being secured in place in a manner contingent on the cir- circumstances prevailing.

The outer cap part, as illustrated, can have different forms and can be adapted to the form of the handle or like turning device by means of which the lock mechanism is operated. The fact that the security cap or cover can be reused eli¬ minates time wastages in obtaining a new security cap and in obtaining the services of a fitter to fit the same.

The outer cap part may be made luminescent, to enable be seen in the dark