GB2293198A - A door latch having a serrated striker element - Google Patents

Abstract

A door assembly comprises a door, a latch and a striker element having a plate 2, the latch having a latch bolt 10 and the striker element being provided with one or more serrations 6 for engaging the latch bolt. The serrations 6 may be notches, grooves, ramps and teeth or beads, but are preferably ramped teeth. The door assembly preferably further comprises a spring action automatic swing door closer. The striker element is fixed to a door jamb (30, fig 4) by fixing screws inserted into holes 8. The door closer, latch striker element and latch may be provided in kit form. <IMAGE>

Description

IMPROVEMENTS IN DOOR LATCHING The present invention relates to improvements in door latching.

A common type of conventional internal door latch arrangement consists of a latch in the door and a receiver in the door jamb. The latch includes a sprung latch tongue (commonly referred to in the art as a latch bolt) which is retractable by the door handle and when closing the door. In such arrangements, the receiver is normally a metal plate with a rectangular hole to receive the latch bolt, the door jamb normally being rebated behind the hole. The receiver also has an angled striker plate adjacent the hole.

As the door is pushed or pulled closed, the latch bolt hits the striker plate and the striker plate forces the latch bolt inwardly against its spring biasing. The latch bolt runs along the striker plate in this position until it aligns with the hole in the receiver. The spring then biases the latch bolt outwardly when it enters the hole, latching the door closed.

In another common type of latching arrangement usually referred to in the art as a rim lock, the latch is mounted on one side of the door and the receiver takes the form of a metal box (called a box striker) mounted on the side of the door frame. Here, as the door is pushed or pulled closed, the latch bolt hits the box striker/receiver and is forced inwardly against its spring biasing until it moves over the rim of the box to align with the interior of the box. The spring then biases the latch bolt outwardly and into the box striker/receiver, latching the door closed.

Such conventional arrangements work satisfactorily in most circumstances. However, they present problems when the door is fitted with some kinds of automatic door closers. Such door closers are frequently required in order to meet fire regulations, which may for instance require that the entrance doors of apartments which open to a central access hallway or stairwell of an apartment block be self-closing.

Different types of door closers are available. Common are automatic swing door closers, including surface mounted closers designed to be fixed to the exterior of the door.

Less obtrusive are closers of the kind designed to be concealed within the width of the door, an example of which is shown diagrammatically in Fig. 1 of the accompanying drawings.

Referring now to Fig. 1, a door 20 fixed to door jamb 22 is provided with a concealed door closer 24. The closer comprises a connecting element (shown as chain 26; a metal strap is a common alternative) fixed to a door plate 28 at one end and to a spring 30 (partially revealed by a cutaway in Fig. 1) at the other end. A closer of this type therefore acts to close the door 20 in the direction of the arrow by the action of spring 30 via the chain 26.

However, because the closers described above (particularly those of the type shown in Fig. 1) are relatively untensioned when approaching the latch position (to avoid slamming), they often exert too small a closing force to achieve proper latching of the door.

The result is that the door remains ajar with the sprung latch bolt "stalled" against the striker plate, instead of received within the receiver hole (or in the case of rim locks, "stalled" against the exterior rim of the box striker). In this condition, draughts can blow the door open (against the door closer), and during a fire this can permit rapid spread of smoke and flames. Moreover, a failure of the door to properly and automatically latch would result in the door failing to meet existing fire regulations.

One solution to this problem has been to replace the conventional receiver/striker by a cam-acting device as described in BP 986945. However, such devices have moving parts which may jam and which are prone to vandalism.

The present invention provides an elegant, inexpensive and reliable alternative solution to this problem and permits positive latching using any automatic swing door closer (including the popular hidden door closers of the type shown in Fig. 1).

According to the present invention, there is provided a door assembly comprising a door, a latch and a striker element, the latch having a latch bolt and the striker element being provided with one or more serrations for engaging the latch bolt.

The serration or serrations provided in the striker element of the invention permit engagement of the latch bolt during closing such that, depending on the force exerted e.g. by an automatic door closer, the latch bolt may engage with any one of the serrations. The door assembly is thus provided with one or more intermediate positions in which the latch bolt positively latches the door, so that draughts cannot subsequently blow the door open.

Preferably, the door assembly of the invention comprises a striker element provided with one to eight (preferably two to five) serrations. Where five serrations are provided, depending on the force exerted by the door closer the latch bolt may engage with any one of the first to the fifth serrations. In each case, positive latching is achieved.

The striker element may be provided with breakpoints along its length so that it can be easily adapted to suit the width of any door jamb during fitting by the user. In this embodiment, a portion of the striker element bearing terminal serrations is snapped off (e.g. using pliers) to adapt the striker element to the width of the door jamb so that excessive overhang beyond the door frame is eliminated.

The serrations are preferably ramped teeth, but may take any form so long as positive engagement with the latch bolt can occur. For example, the serrations may take the form of notches, grooves, ramps, teeth or even beads.

The serrated striker element of the invention may be used in conjunction with a latch bolt receiver. The receiver may for example be in the form of a plate with a hole to receive the latch bolt. In such embodiments the striker element of the invention may be associated with or form part of any such latch bolt receiver.

In the case where the door assembly comprises a rim lock, the serrated striker element of the invention forms part of the box striker and is disposed to engage with the latch bolt of a rim latch.

Because of the advantages attendant on the use of the present invention with automatic swing door closures (as explained above), the door assembly of the invention preferably further comprises an automatic swing door closer, preferably a spring-action concealed door closer as shown in Fig. 1 of the accompanying drawings.

The serrated striker of the invention may be provided alone (for example as a replacement for an existing conventional latch bolt receiver/striker plate), or as part of a kit with a door latch and/or a door closer.

The invention will now be described in more detail by way of example of specific embodiments. The embodiments are presented by way of exemplification, and is in no way intended to limit the scope of the invention. The embodiments will be described with reference to the accompanying drawings in which: Fig. 2 is a diagrammatic perspective view of a striker element according to the invention.

Fig. 3 is a diagrammatic perspective view of a striker element according to the invention showing a latch bolt engaged therewith.

Fig.4 is a diagrammatic perspective view of a striker element according to the invention fitted to a door jamb.

Fig. 5 is a diagrammatic perspective view of an integral striker element/receiver according to the invention fitted to a door jamb.

With reference to Fig. 2, the serrated striker element of the invention comprises a plate 2 having four notches 4 defined by four ramped teeth 6. The striker element is provided with fixing holes 8 (only one of which is shown in Figs. 2 and 3) for receiving a screw or similar fixing means so that the element can be secured to a door jamb.

Once fixed to a door jamb the notches 4 in the striker plate 2 permit engagement of a latch bolt 10 of a latch during closing of a door such that, depending on the force exerted e.g. by an automatic door closer, the latch bolt may engage with any of the four notches to positively latch the door, so that draughts cannot subsequently blow the door open. Depending on the force exerted by the door closer, the latch bolt may engage with any of the first to fourth notches: in Fig. 3, engagement with the second notch is shown.

Figure 4 shows a striker element similar to that shown in Fig. 2 fitted to a door jamb 30. The striker element 32 is recessed into a rebate 34 in the door jamb. The depth of the rebate is adjusted (usually after the door is hanging) such that the sprung latch bolt can easily (but securely) engage with at least the first notch of the striker element. Depending on the length of travel of the sprung latch bolt and the gap between the edge of the door and the jamb, the striker element is usually recessed such that the tips of the teeth 36 defining the notches 38 in the striker element lie up to 10mm below the surface of the door jamb, though it could be flush with the surface of the jamb or even protrude therefrom, depending on the setting of the door hinges.

During the closing of the associated door, the latch bolt of the door will hit the edge of the serrated striker shown on the left hand side of Fig. 4 and will then sequentially engage the notches 38 of the striker element until the fully closed position is reached.

In Fig. 4, the striker element is shown fixed in a plane parallel to that of the door jamb: the striker element can also be fixed so that it lies on a slope, the edge shown on the left hand side in Fig. 4 being more deeply rebated.

In alternative embodiments, the striker element can be provided with two or more serrations, the serrations being arranged such that in use the serration which is struck first by the sprung latch bolt is engaged with less closing force than the second and any subsequent serration.

For example, the striker element can itself be wedgeshaped in longitudinal cross section, or the serrations otherwise arranged such that in use the serration first struck by the sprung latch bolt lies below the second and any subsequent serrations. Preferably, any subsequent serrations are arranged such that they progressively increase in height.

In these embodiments, the first serration is engaged with less closing force than the second serration, progressively more force being required to engage later serrations until the fully closed position is reached. In such arrangements the extent of travel of the latch against the bias of its spring needed for positive engagement with a serration gets progressively larger as each subsequent serration is encountered during the closing of the door.

The serrated striker element of the invention may be made and sold separately to the rest of the door assembly and can even form a replacement to a door assembly originally fitted with a standard striker plate. Alternatively, the serrated striker element can also be formed integrally with a receiver, as shown in Fig. 5.

In Figure 5, the integral striker/receiver of the invention 40 is rebated into the door jamb 42. The receiver hole 44 is in the standard form, but the striker plate 46 is formed with a series of bent-out tongues 48 which define serrations. The striker plate is set at a slope, so that the first bent-out tongue is further away from the edge of the door. The bent-out tongues are therefore arranged such that in use the bent-out tongue which is struck first by the sprung latch bolt is engaged with less closing force than the second and any subsequent bent-out tongue.

During the closing of the associated door, the latch bolt of the door will hit the edge of the striker plate 46 shown on the left hand side of Fig. 5 and will then, depending on the closing force applied, sequentially engage the bent-out tongues 48 of the striker element until the fully closed position is reached in which the sprung latch bolt is recieved in the receiver hole 44.

Claims (16)

CLAIMS:

1. A door assembly comprising a door, a latch and a striker element, the latch having a latch bolt and the striker element being provided with one or more serrations for engaging the latch bolt.

2. The door assembly of claim 1 wherein the striker element is provided with two or more serrations, the serrations being arranged such that in use the serration which is struck first by the sprung latch bolt is engaged with less closing force than the second and any subsequent serration.

3. The door assembly of claim 1 or claim 2 wherein the striker element is provided with one to eight (for example two to five) serrations.

4. The door assembly of any one of the preceding claims wherein the serrations are defined by notches, grooves, ramps, teeth or beads.

5. The door assembly of claim 4 wherein the serrations are ramped teeth.

6. The door assembly of any one of the preceding claims further comprising a latch bolt receiver.

7. The door assembly of claim 6 wherein the striker element is associated with or forms part of the latch bolt receiver.

8. The door assembly of claim 7 wherein the latch bolt receiver is a box striker and the latch is a rim latch.

9. The door assembly of claim 6 or claim 7 wherein the latch bolt receiver is a plate with a hole to receive the latch bolt.

10. The door assembly of any one of the preceding claims further comprising a door closer, for example an automatic swing door closer.

11. The door assembly of claim 10 wherein the door closer is a spring action concealed door closer.

12. The door assembly of claim 11 wherein the door closer is substantially as hereinbefore described with reference to Fig. 1.

13. A door latch set comprising a latch and a striker element, the striker element being as defined in any one of the preceding claims.

14. A door closing kit comprising a door closer (for example a door closer as defined in claim 11 or claim 12), a latch striker element and optionally a latch, the striker element being as defined in any one of the preceding claims.

15. A striker element as defined in any one of the preceding claims for use with the door assembly of any one of claims 1-12, the door latch set of claim 13 or the door closing kit of claim 14.

16. A striker element substantially as hereinbefore described with reference to Figs 2-5, or a door assembly, door latch kit or door closing kit comprising said striker element.