The present invention relates to door locking devices. More specifically, the invention relates to a new type of electrical door strike with fire protection, designed to permanently close the electrical door strike in the event of fire.

European standards require that doors defined as fire doors must remain closed during fire (EN1634-1 in 2017). The purpose of this is to prevent the supply of oxygen to the fire so that it does not spread, and in addition to make it easier to extinguish the fire.

Fire doors are certified according to EN1634-1 in 2017 according to how long they can withstand temperatures of 1000 degrees Celsius. Various certifications are given for doors that withstand temperatures of more than 1000 degrees Celsius for more than 30, 60 and 120 minutes.

Many conventional closing and locking mechanisms used in doors are based on mechanical springs. Because springs often lose their standard properties at high temperatures, a number of closing and locking mechanisms have trouble keeping a door closed during a fire. It is therefore desirable to use special locking mechanisms specially designed to keep doors closed in the event of fire. These are often defined either as fire fuses or fire locks.

The most common fire protection concepts used today are based on heat-triggered mechanisms. For example, there may be materials that melt and, consequently, release a lock on a suspension system, for example by locking and locking in a locking position by gravity (An example is described by W. R. Foshee in CA1312640C - 1987). Alternatively, the fire protection mechanism may be based on materials that expand and thus block the functionality of one or more of the door's fittings, and thus lock the door.

US 4015869 discloses a catch mechanism for installation in a door frame to cooperate with a door lock on a fire door. The mechanism includes a catch member pivotable between an operative position in which to serve as a door catch and an inoperative position to enable release of the door no matter what the condition of the door lock. The mechanism includes a heat responsive locking device which locks the catch member in its catch position in the event of a fire generating high temperatures. The locking device may comprise a biased locking plunger mounted in a cavity within the catch member and normally held in a retracted position by a heat fusible metal plug but extendible on melting of the plug to engage the catch body and so lock the catch member.

US 5782509 describes an assembly in a door closing unit, the assembly comprising a latch bolt element; carrier structure to carry the bolt element to pivot between door unlatched and latched position; and means carried by a fire resistant portion of the assembly to be responsive to an increase in temperature to a level T to move into position to block door unlatching movement of the bolt element from door latching position.

CN 206279967 U describes a fire door fuse with heat lock function, including door frame and door leaf. The invention is provided with a hole on the door leaf, and the door frame is provided with a corresponding hole and the fire door heat lock function is equipped with a pin which can be partially extended into the hole for the fire door and stops the door leaf when heated.

US 4598939 discloses an auxiliary bolt exit device which when held in by the door bolt allows a locking pin to prevent unauthorized forced retraction of the main lock bolt. Normal operation of the unit by turning the panic bar locks the leg out of the way and then pulls in the main lock bolt.

The problem with today's solutions is that they are often complex and consist of many different components, they are expensive to produce, they take up too much space, or they are not reliable enough to meet the requirements set by the fire regulations. The object of the present invention is to provide a cheaper, simpler, smaller size and more reliable fire protection for doors.

The invention comprises a fire protection in an electrical door strike, the purpose of which is to permanently close it in case of fire. The fire protection itself is directed to a type of locking device which is used in electrical strikes that contain an open and close mechanism. The electrical door strike comprises a door strike house and a movable strike keeper (also known as a lip), and the fire protection is designed to lock the strike keeper in the electrical door strike house.

The invention comprises a locking mechanism between a door strike house and a movable strike keeper comprising; a cavity in the door strike house, a cavity in the strike keeper which is in line with the cavity of the door strike house when the strike keeper is in the closed position, at least one locking object located at the bottom of the cavities in the door strike house and strike keeper respectively. The two locking objects are attached with fastening means that releases when the temperature exceeds a threshold temperature and the two locking objects has a vertical extension which in total is greater than the length of the cavity and the distances between electrical door strike house and strike keeper.

The invention is based on the fastening means releasing the locking objects as a result of fire and the upper locking object falling as a result of gravity. The locking object ends in a position where it is simultaneously inside the cavity in both the electrical door strike house and the strike keeper, thus locking the two so that they cannot move relative to each other. This causes the electrical door strike, and consequently the door, to be permanently locked.

The enclosed figures are intended to clarify some embodiments of the invention. Same numbers in different figures indicate the same features of the invention.

• Figure 1 shows an electrical door strike.
• Figure 2 shows a principle sketch of the electrical door strike and strike keeper with associated fire protection, before the fire protection is released.
• Figure 3 shows a principle sketch of the electrical door strike and strike keeper with associated fire protection, after the fire protection has been triggered.
• Figures 4 and 5 show the same as Figures 2 and 3, but with a different embodiment of cavities and blocking objects.

The invention comprises a fire protection for door locking devices comprising an electrical door strike designed to permanently lock the electrical door strike in rase of fire.

A number of door locking devices are based on the opening and closing mechanism being located in an electrical door strike 1 (also known as a locking post) such as the locking device shown in Figure 1. An electrical door strike is the part of the locking device which is in the door frame, and in these cases has a movable part 2 which can be opened and closed as needed by means of a mechanical or electronic device. The movable portion of the electrical door strike is often referred to as a metallic lip, but will hereinafter be referred to as a strike keeper 2. It is designed so that it can be opened and closed along a direction of movement, where it prevents, for example, a latch bolt or dead bolt, mounted in the door leaf, in sliding past so that the door can be opened.

The invention comprises a fire protection designed to permanently lock an electrical door strike 1 which can be opened and closed by means of a movable strike keeper 2. More specifically, the invention comprises a locking mechanism for an electrical door strike, wherein the movable strike keeper is permanently locked in an electrical door strike house 3 so that the two cannot move relative to each other. The electrical door strike house 3 is here defined as the electrical door strike minus the movable strike keeper 2 and the mechanism inside.

The invention comprises a locking mechanism between an electrical door strike house 3, secured in a door frame by a fire door, and a movable strike keeper 1 wherein the locking mechanism comprises: a vertical cavity 5 in the electrical door strike house, a vertical cavity 6 in the strike keeper which is in line with the cavity of the electrical door strike house when the strike keeper is in the closed position, and at least one locking object 7, 8 located within each of said cavities. That is, at least one locking object 7 in the cavity of the electrical door strike house 3, and at least one locking object 8 in the cavity of the strike keeper 2. The locking objects may be spherical, cylindrical, oval or multilayered. When it comes to choice of shape, the sphere shape has the advantage that this shape is least sensitive to impurities. Another preferable shape is a cylinder that is spherical at each end. The locking objects 7, 8 are secured with fastening means which release the locking objects when the temperature exceeds a threshold temperature and allow them to fall. The two locking objects have a vertical extension which is in total greater than the length of a cavity, so that the upper locking object blocks movement between the electrical door strike house and the strike keeper when the locking objects are released and allowing the upper locking object to fall into a locking position if the temperature exceeds the threshold temperature as shown in figures 2-5.

Depending on which way the door sits, one of the cavities 5, 6 will be at the top. The locking object in the upper cavity will then fall down and lock the strike keeper to the electrical door strike house when the threshold temperature is exceeded, such as in case of fire.

The fastening means may be tin or other metals and metal alloys having a suitable melting point or an adhesive which loosens at the threshold temperature. The outer extent of the fastening means in the cavities is indicated in Figures 2-5 with a dotted line.

The locking object itself must be strong enough to prevent the strike keeper from moving relative to the electrical door strike house. It must also withstand temperatures up to 1000 degrees Celsius to keep the locking device closed even under heavy fire. A material that meets these requirements is stainless steel, but materials such as chromium, copper, nickel and titanium or special alloys based on, for example, aluminum, copper, iron, molybdenum and / or nickel will also be suitable.