The present invention relates to a door closing apparatus for closing a hinged door.

In museums, castles, exhibition buildings and other buildings where the public is admitted the doors are normally main¬ tained in an open position during the opening hours. Outside the opening hours, however, it is important that the doors are closed. Furthermore, in case of fire the doors should be able to close automatically if they are not closed already.

Several types of door closing apparatuses are known. Examples of such door closing apparatuses are disclosed in NO-136159B, DE-41 24 282C, DK-163889B, and SE-462.866B. Especially in old buildings it is important that door closing apparatuses are arranged in a substantially concealed position. Furthermore, it is desirable that the door may be retained in an open position defining an angle of between 90° and approximately 180° with the closed position.

The object of the present invention is to provide a door closing apparatus which can fulfil these requirements.

Thus, the present invention provides a door closing apparatus for closing a hinged door, said apparatus comprising a hous¬ ing, a shaft extending substantially along a longitudinal axis of the housing and being rotatably mounted therein, a connecting arm mounted at one end of the shaft and extending transversely thereto, the other end of the connecting arm being adapted to cooperate with a guide track, which is formed on the door and which extends transversely to the hinge axis of the door, whereby the door may be moved from an open to a closed position when the door is rotated from a first to a second rotational position, locking means.for locking the shaft in said first rotational position, and driving means for driving the shaft from said first to said

second rotational position, when the locking means are released.

The housing of the door closing apparatus may be arranged in a recess or well formed in the floor or ceiling and in a position closely adjacent to or behind the door when the door is open. The door may be moved from its closed to its open position manually or mechanically by means of a driving motor, whereby the shaft is rotated from the second to the first rotational position. The shaft is locked in its first position by the releasable locking means, whereby the door is retained in its open position.

When the door is to be closed, for example in case of fire, the locking means may be manually or automatically released, whereafter the door is closed by the driving means driving the shaft from its first to its second rotational position.

The driving means should be sufficiently forceful to ensure closing of the door after release of the locking means. On the other hand, however, the speed of the closing movement should be restricted to avoid damage of the door and hurting of a person standing an or close to the door opening. There¬ fore, the door closing apparatus may further comprise means for reducing the speed of the rotational movement of the shaft from its first to its second position, whereby also the speed of the door closing movement is reduced.

The speed reducing means may comprise any suitable braking device, such as a hydraulic or mechanical brake. In the preferred embodiment, however, the speed reducing means comprise an eddy-current brake coupled to said shaft.

The driving means for driving the shaft from its first to its second position and thereby for driving the door from its open to its closed position may be of any suitable type. In the presently preferred embodiment the driving means comprise a spring, such as a spiral spring or coil spring, being

tightened when the shaft is rotated from its second to its first position. As an example, the spring may be arranged around the shaft, and when the locking means are released the tightened spring will return the open door to its closed position.

Alternatively, the driving means may comprise an electric motor which is energized when the locking means are released, and which is adapted to rotate the shaft from its first to its second position, whereby the door is closed. The electric motor may also be used to rotate the shaft from its second to its first position and thereby to open the door.

The locking means may be mechanical locking means which are preferably adapted to be released automatically in case of fire. Release of the locking means could also be possible by actuating an electrical switch or another control member.

In the preferred embodiment, the locking means comprise electromagnetic means retaining the shaft in said first position when energized. The electromagnetic means, which may, for example, be an electromagnetic braking or retaining device, may be controlled by an electric control circuit, so that the shaft is released in case of fire, or when a control switch is actuated.

The speed reducing means and/or the locking means may be connected to the shaft via a reduction gear. This means that the speed reducing means, such as the eddy-current brake, rotates at a rotational speed which is several times higher than the rotational speed of the shaft, whereby a speed reducing effect is increased. Because of the reduction gear the minimum locking force or electromagnetic force to be generated by the locking means may be reduced.

The door closing apparatus according to the invention may further comprise position indicator means for automatically actuating the locking means so as to lock the shaft when the

shaft is in its first position. This means that when the door is opened manually or automatically, the opening movement of the door-will be stopped when the desired open position of the door has been reached, which means that the shaft is in its first position. The position indicator means may comprise a microswitch mounted on the housing and a microswitch actuator mounted on the shaft. Alternatively, the position indicator means may comprise a- light diode and a photoelec¬ tric cell mounted on the housing and on the shaft, respec- tively, or vice versa.

Some of or all of the door closing apparatus mounted in connection with the various doors of a building may be con¬ trolled by a common electrical control circuit which may receive position signals from the position indicator means, and which may control the locking means. In case of double doors the control circuit may ensure that the doors of a double door are closed in the right order.

The housing of the door closing apparatus preferably has a substantially cylindrical outer wall surface having an axis coinciding with or being parallel with the axis of the shaft. The housing may then be mounted in a cylindrical recess or hole drilled in the floor or ceiling of the building in question.

According to a further aspect the present invention provides a door arrangement comprising a hinged door having a guide track extending transversely to the hinge axis of the door • and a door closing apparatus as described above, the housing ^' of the closing apparatus being mounted stationarily in rela¬ tion to the hinge axis of the door and said other end of the connecting arm of the closing apparatus being mounted so as to be slideable along the guide track.

The guide track may be defined in or mounted on any of the opposite side surfaces of the door at the bottom end thereof. However, the guide track is preferably mounted on or defined

SUBSTITUTESHEET

in the door in a concealed or less visible position. Thus, the guide track preferably extends along the lower end sur¬ face of the door. Furthermore, at least the major part of the housing of the closing apparatus is preferably arranged below a floor surface positioned opposite to and below the lower end surface of the door. Thus, the housing of the apparatus may totally or partly be mounted in a recess or cutout extending from the floor surface, such as a cylindrical hole bored in the floor.

The invention will now be further described with reference to the drawing, wherein

Fig. 1 is a diagrammatic side view of a door closing appara¬ tus according to the invention, Fig. 2 is a plan view showing a door arrangement comprising the closing apparatus, which is mounted in a recess formed in a floor, and which is connected to a hinged door, and Fig. 3 is a plan view diagrammatically illustrating where the door closing device may be mounted in relation to the door to be closed.

The door closing apparatus or door closing device shown in Fig. 1 comprises a cylindrical housing 10 having a central shaft 11 rotatably mounted therein. A drum 12 is mounted around and fixed to the upper end on the shaft 11, and a spiral spring 13 is arranged around the drum 12 such that the spring 13 is tightened when the shaft 11 and the drum 12 mounted thereon are rotated in one rotational direction. The door closing apparatus further comprises an eddy-current brake 14 including permanent magnets 15 which are arranged stationarily in relation to the housing 10 and a rotatable metal disc 16, for example of copper, arranged closely adja¬ cent thereto. The shaft 11 is coupled to the shaft of the disc 16 via a pair of reduction gears 17 and 18, which may, for example, be planet gears ^" each having a gear ratio of for example 1:8. This means that when the shaft 11 is rotated the disc 16 rotates at a much higher rotational speed. An elec¬ tromagnetic locking device 19 is arranged at the bottom end

of the housing 10 and coaxial therewith. The locking device 19 is adapted to lock the disc 16 and consequently also the shaft 11 in a stationary position when the locking device 19 is energized.

A microswitch 20 which may cooperate with a switch actuator (not shown) mounted on the shaft 11 or drum 12, is mounted on the upper end surface of the housing 10. The actuator is arranged in such a position that the switch 20 is activated when the shaft 11 has been moved to a first rotational posi- tion against the bias of the spring 13. Actuation of the spring 20 causes the locking device 19 to be energized, whereby the shaft 11 is retained in this position. It should be understood that the microswitch 20 and the associated actuating member could be replaced by any other kind of a position indicating means, such as a light diode and an associated photoelectric cell.

As shown in Fig. 2, the door closing apparatus shown i Fig. 1 may be mounted in a cylindrical recess formed in a floor part close to a door 21. The upper end surface of the housing 10 is positioned below or is substantially aligned with the upper floor surface so that only the upper end of the shaft 11 extends upwardly from the floor surface. A connecting arm 22 is fastened to the upper end of the shaft 11 and extends radially therefrom. A stud or pin 23 formed at the outer end of the arm 22 is in slidable engagement with a guide rail 24 formed in the lower end surface of the door 21.

When the door 21 which is mounted pivotally about the verti¬ cal axis of door hinges 25, is moved from its closed position shown in Fig. 2 to an open position the connecting arm 22 is moved counterclockwise to a position in which the microswitch 20 is actuated, whereby the electromagnetic locking device 19 is energized. The energized locking device retains the shaft 11 and thereby also the connecting arm 22 and the door 21 in its open position.

When the locking device 19 is released, for example after termination of opening hours or in case of fire, the door 21 will be moved to its closed position under the bias of the spring 13. The speed of the closing movement is, however, reduced by the action of the eddy-current brake 14.

The door closing apparatus according to the invention renders it possible to obtain an angle of up to 180° between the closed position and the open position of the door 21. Fig. 3 indicates an angular sector 26 in which the housing 10 of the door closing apparatus may be mounted. It is appreciated that even when the open position of the door defines an angle with the closed position substantially exceeding 90°, the door closing apparatus may be arranged behind the door in its open position. When the door is opened almost 180°, the door closing apparatus may be positioned in front of but closely adjacent to the opened door. However, as the housing 10 may be concealed below the floor surface the door closing appa¬ ratus is almost invisible also when the door has to be opened approximately 180°.

It should be understood that various amendments and modifica¬ tions of the door closing apparatus and the door arrangement described above may be made without departing from the scope of the present invention. As an example, in order to increase the door closing force of the apparatus two or more spiral springs may be arranged coaxially on top of each other.

Furthermore, the connecting arm 22 shown in Fig. 2 may be replaced by an arm having a curve or an angular space. It will then be possible to position the housing 10 of the door closing apparatus in a recess formed not only within the angular sector 26, but also within a neighbouring sector 27 indicated by dotted lines in Fig. 3.