The locking mechanism, which is accommodated in the lock housing embedded in the floor under the door, essentially comprises a pivot pin which protrudes upwardly from the lock housing with one end and whose other end is received and non- rotationally fixed in an receiving bush rotatably supported in the lock housing. The receiving bush is surrounded by a cam plate which is fixed at the receiving bush and engaged by a spring-mounted, longitudinally displaceable piston. A rotary motion of the pivot pin, whose protruding free end engages a matching recess of a pivot pin seat provided in the door, thus causes a longitudinal displacement of the piston. The locking mechanism further comprises a pressure fluid, valves, seals and gaskets and the likes, which are arranged inside the lock housing so that the opening motion of the door is dampened.

During assembly of the door, the lock housing is inserted into the box-shaped outer casing installed in the floor, and fixed therein by means of a fastening device. The box-shaped outer casing is usually a box made of metal, plastic material, cement and the like, and is already embedded and fixed at the required position in the floor, i. e. under the door opening or threshold, by a method such as concrete-setting. Since the outside of the lock housing is designed such that it corresponds to the shape and size of the locking mechanism received therein, and the outer casing is only available in standard sizes, it is necessary to provide fastening devices adapted to the lock housing, by means of which the housing may be fixed at the required position in the outer casing. The housing has to be positioned such that the pivot pin is

arranged in alignment with the matching pivot pin recess in the door to ensure that the door may be pivoted, and such that the locking piston is properly aligned relative to the door.

A floor-embedded door locking device known from DE 36 40 812 A1 comprises an outer casing and a lock housing inserted into said outer casing, with the lock housing having a fastening member in the form of an angle steel which is arranged at its end face remote from the pivot pin, with one side of said angle steel abutting against the outer casing. One leg of the angle steel is screw-fitted to the end face of the lock housing, whereas the other leg comprises a rectangular bend on its lower side, and protrudes from the lock housing as a longitudinal extension thereof. The lock housing is screw-fitted to the outer casing at its front edge remote from the protruding leg of the angle steel, and the rectangular bend of the angle steel has an elastic support member and a clamping piece arranged thereon, with said clamping piece abutting against the elastic member and comprising a wedge surface. An adjusting screw is threaded into said bend and extends through said clamping piece and support member so that it presses the support member against the wall of the outer casing, whereby the opposite front edge of the lock housing is pressed against the outer casing.

It is an object of the present invention to provide a floor- embedded door locking device of the initially described type, comprising a fastening device by means of which the lock housing may be fixed in the outer casing at any desired position regardless of the outer shape and dimensions of the lock housing, respectively, and which eliminates the need to provide any fastening means at the lock housing itself.

According to the present invention, the fastening device is placed between a wall of the outer casing and the lock housing, with the fastening device comprising a support plate supported at the wall of the outer casing as well as a threaded bolt projecting from said support plate, with an adjusting nut designed as a tapped bush being screwed on said threaded bolt

and abutting against the lock housing in a clamping manner at its front side facing away from the support plate.

The present invention enables any type of lock housing to be secured to a common outer casing in any desired position.

During assembly, the lock housing is first placed in the outer casing and aligned such that the pivot pin protrudes from the floor-embedded locking device in the very position required for the door to be placed upon it. Then, the support plate comprising the threaded bolt protruding therefrom is placed in the space between the lock housing and the outer casing, with the rear side of the support plate abutting against a wall of the outer casing, and the threaded bolt having the adjusting nut threaded thereon facing towards the lock housing. Next, the adjusting nut is rotated on the threaded bolt so that its front side opposite the support plate moves towards the lock housing until it abuts against the lock housing. If the adjusting nut is threaded further against the lock housing - simultaneously with additional similar fastening devices, if necessary - the lock housing will be clampingly held in the outer casing.

A particular advantage of the present invention consists in the fact that the fastening device according to the present invention enables any possible distance or gap between the lock housing and the outer casing to be bridged. Furthermore, the adjusting nut of the fastening device may abut against the lock housing at any desired position of the latter, regardless of the external shape of the lock housing which may be a box-shape with plane side faces, or an uneven shape. Said fastening device also enables a subsequent fine adjustment of the lock housing in the outer casing so that the free end of the pivot pin protrudes from the floor-embedded locking device exactly at the required position and orientation.

According to a further embodiment of the present invention, the bottom of the outer casing is provided with a groove which is spaced apart from and runs parallel to the walls of the outer casing so that the lower front edge of the support plate may be

placed therein. This is particularly advantageous since the fastening device thus no longer needs to be held manually in the outer casing while the lock housing is being secured or clamped to the outer casing, as the support plate is inserted with its front edge into said groove where it is kept in position. The groove is formed with such a width that the support plate is slidingly received therein, and may thus be moved in the desired clamping position. Alternatively, the outer casing may also comprise a circumferential bulge instead of a groove, which extends along the wall at a distance therefrom, so that the front edge of the support plate may be received between said bulge and the wall.

According to another further embodiment of the present invention, a front edge of the support plate has a U-shaped bracket formed thereon, with the support plate being attachable to the wall of the outer casing by means of said bracket. The U-shaped bracket may be formed, for example, by accordingly bending a front edge of the support plate. In this embodiment, the support plate is suspended at the wall of the outer casing and may be displaced along the wall of the outer casing into the desired position, while it is not necessary to additionally hold the support plate when the adjusting nut is being threaded on the bolt.

According to yet another embodiment of the present invention, the wall of the outer casing is provided with a film made of magnetizable material, and the support plate comprises a no- work magnet at its contact surface facing the wall of the outer casing, which magnet magnetically interacts with the film. In case of the outer casing being made of plastic material, its inner wall may be provided with a film made of magnetizable material, for example, so that the support plate having a no- work magnet at its contact surface facing the wall may adhere to said wall. However, the wall of the outer casing may also be provided with a metallic plate mounted thereon. The no-work magnet of the support plate may be formed as a plate, and may be fixed to the support plate by means of an adhesive. In this

embodiment, the support plate may be adhered to the outer casing at any desired position thereof.

According to a further embodiment of the present invention, the adjusting nut which is formed as a tapped bush is conically tapered at its free end facing away from the support plate, and has a truncated end. The particular advantage of this conically ending adjusting nut consists in the fact that the nut has a small contact area with the lock housing so that the clamping pressure at the lock housing will be increased. However, the tapped bush may also abut against the lock housing with its free annular end face.

According to another further development of the above embodiment, the truncated clamping face of the tapped bush is provided with a profile so that the contact face by means of which the tapped bush abuts against the lock housing ensures a good adhesion in addition to a high clamping pressure.

According to yet another development of the above embodiment, the conical end terminates in a tip which may penetrate into the surface of the lock housing so that a reliable clamping joint is formed.

The adjusting nut formed as a tapped bush can be made of either metal, plastic material or metal having a plastic coating.

According to another embodiment of the present invention, the threaded bolt of the fastening device is formed as a countersunk head screw. In this embodiment, the support plate has a countersinking in its contact surface facing the wall of the outer casing, wherein the head of the countersunk head screw is arranged such that it is flush with the surface. If the support plate, which may also be formed of a non-metallic material, is made of metal, the threaded bolt may be welded to the support plate in another further development of the present invention.

The present invention will now be explained in more detail and by way of example with reference to the accompanying drawing showing schematical views of embodiments of the present invention.

Fig. 1 shows the top view of an outer casing having a lock housing placed therein and clamp-fitted thereto.

Fig. 2 shows a fastening device comprising a support plate with a U-shaped bracket.

Fig. 1 shows a floor-embedded locking device having an outer casing 1 wherein a lock housing 2 is placed. A pivot pin 3 which is part of the locking mechanism protrudes from the lock housing 2 so that a door (not shown) may be pivotally received thereon. The lock housing 2 is clamp-fitted by means of four fastening devices 4 which are disposed in the spaces between the wall of the outer casing 1 and the lock housing 2. The outer casing 1 has a circumferential groove 5 formed in its bottom so that it runs parallel to the wall, wherein the lower edges of support plates 6 are received and held.

Each support plate 6 has a threaded bolt 7 arranged thereon which is perpendicular to the contact surface of the support plate 6. Each threaded bolt 7 has an adjusting nut 8,9, 10, and 11, respectively, designed as a tapped bush threaded thereon, the free end of which nut clampingly abuts against the lock housing 2. After the lock housing 2 has been placed in the outer casing 1, it is adjusted such that the pivot pin 3 has the desired position. At this time, the adjusting nuts 8,9, 10 or 11 are still in a position on the threaded bolts 7 in which their free ends do not contact the lock housing 2. The adjusting nuts 8,9, 10,11, which may be provided with contact surfaces for a wrench, for example, are then rotated so that they move towards the lock housing 2 to a position where they abut against the latter. Upon further rotation of the adjusting nuts 8,9, 10,11, the lock housing is eventually clamp-fitted in the outer casing 1, with the support plates 6 being

supported at the respective walls of the outer casing 1 and the free ends of the adjusting nuts 8,9, 10,11 clampingly abutting against the lock housing 2.

The designs of the adjusting nuts 8,9, 10,11 may differ insofar as the free ends of said adjusting nuts may be provided with different contact surfaces, as may be seen from Fig. 1. It is common practice, however, to use the same type of adjusting nuts 8,9, 10 or 11 in one and the same application. The adjusting nut 8 has a conical free end which terminates in a tip. Adjusting nut 9 has a truncated free end, with the truncated surface abutting against the lock housing. Adjusting nut 10 is a variation of the truncated nut, with the contact surface of the truncated end being additionally provided with a profile so that a particularly good adhesion at the lock housing 2 is ensured. Adjusting nut 11 is a simple tapped bushing whose annular end face abuts against the lock housing 2.

As an alternative or in addition to the arrangement of fastening devices 4 shown in Fig. 1, fastening devices may also be positioned at the end walls of the outer casing 1 and, thus, abut against the end faces of the lock housing 2, i. e. the fastening devices 4 may be arranged at any desired position within the outer casing.

As shown in Fig. 2, the support plate 6 is provided with a U- shaped bracket 12 by means of which it may be suspended from the wall of the outer casing 1. In the suspended state, the support plate 6 may be moved to any desired position within the outer casing 1. An adjusting nut 9 is threaded on the threaded bolt 7 and abuts against the lock housing 2. At its end facing the support plate 6, the adjusting nut 9 comprises engagement faces 13 for the engagement of a suitable tool by means of which the adjusting nut 9 may be adjusted.