AU733379B2 - Door lock - Google Patents

Description

1 P/00/001 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Door Lock oo*::.The following statement is a full description of this invention, including the best method of performing it known to the applicant:- This invention relates to door locks of the kind having a latch bolt that is retractable from a locked position, wherein the latch bolt extends from the door into a recess in the door frame surrounding the door or an opening in a striker plate on that frame, to an unlocked position, wherein the bolt is clear of the recess or opening, by means of an operating mechanism including a manually rotatable operating handle or knob.

More particularly, the invention relates to such locks wherein the latch bolt is flat ended, as distinct from a bolt with an inclined end face and which is thereby adapted to be retracted automatically by sliding contact with a fixed striker plate on the door surround when the door is pushed shut.

Flat ended latch bolts offer greater security, in that latch bolts with inclined ends can be caused to retract by the insertion of a thin, resilient lamina (such as a plastics card) between the bolt and the striker plate.

On the other hand flat ended latch bolts are less convenient in that the operating handle must be used whenever the door is to be latched shut, resulting in a tendency for people to push the door to but leave it unlatched.

Therefore a primary object of the present invention is to provide a door lock mechanism having a flat ended latch bolt, which may be merely swung closed to become latched in the closed position.

The invention is particularly but not exclusively applicable to heavy doors, such as fire doors, which require considerable force to be applied 10 by a person seeking to swing the door from one position to another, and which usually are furnished with locks having a plurality of simultaneously operable latch bolts.

Prior known locks of the kind last referred to have comprised a handle that may be manually rotated about a horizontal axis 15 perpendicular to the plane of the door, a multi-throw crank mechanism rotatable as one with the handle, and two, three or four connecting rods extending from the crank mechanism to the retractable latch bolts at the door edges. The connecting rods have extended generally horizontally and/or vertically to the respective latch bolts, so that the latch bolts have been positioned so as to coincide with vertical and/or horizontal axes extending through the axis of rotation of the handle.

For security reasons it is preferable for the latch bolts to be positioned at or near the mid-points of the respective edges of the door.

Thus, it has been proposed to position the handle at or near the middle of the door. That proposal is not desirable in relation to heavy doors because it is preferable for the handle, on which a person pulls or pushes to swing the door, to be remote from the hinge axis, so as to increase the turning moment about the hinge line for a given force applied to the handle.

The handle of heavy doors is frequently located at the conventional position (about mid-way between the top and bottom of the door, and adjacent the edge remote from the hinge line), and an off-centre position of the latch bolts at the top and/or bottom edge tolerated, even though this renders the door less secure.

Therefore a second object of the present invention, as applied to 10 locks with multiple latch bolts, is to provide a lock wherein each latch bolt is at or near the mid-point of the corresponding edge of the door, while retaining a conventionally positioned operating handle near to the upright edge of the door remote from the hinge line.

A further object of the invention is to provide such a lock adapted to 15 be mounted on a surface of the door (as distinct from being enclosed within the door) so as to simplify its retrofitting to an existing door.

For descriptive convenience the invention is described below as if mounted on a door as it would be when in use. Furthermore, the various edges of the door are referred to as its "hinged edge", being the upright edge adjacent the hinge axis, its "free edge", being its other upright edge opposite the hinged edge, and its "top edge" and "bottom edge", being its upper and lower horizontal edges respectively.

The invention consists in a door lock mechanism comprising at least one flat ended latch bolt, biassing means urging said latch bolt into a latched position wherein the bolt projects beyond an edge of the door, an operating mechanism including a rotatable handle whereby the latch bolt may be drawn, against the effect of the biassing means, into an unlatched, retracted position, and detent means automatically engaging the operating mechanism or latch bolt when the latch bolt is in the unlatched position to then hold the bolt in the unlatched position; said detent means including a striker element adapted to contact the door surround as the door moves into its closed position and thereby disengage the detent means to enable the latch bolt to move into the latched position under the effect of the biassing means.

*10 A preferred multiple latch, door lock mechanism according to the invention comprises a backing piece adapted to be secured to a surface of a door, a master crank mechanism mounted on said backing piece adjacent the free edge of the door at or near the mid-point thereof, a slave crank mechanism mounted on said backing piece at or near the 15 middle point of said surface, linking means connecting the crank mechanisms such that rotation of the master crank mechanism causes corresponding rotation of the slave crank mechanism, at least three latch bolts mounted on said backing piece respectively positioned at or near :mid-points of associated door edges, at least three connecting rods extending respectively from the latch bolts to a said crank mechanism and effecting projection and retraction of the latch bolts into latched and unlatched positions respectively in response to rotation of the master crank mechanism, biassing means urging said latch bolts into the latched positions, and detent means automatically engaging a said crank mechanism when the latch bolts are in their unlatched positions to then hold the bolts in their unlatched positions; said detent means including a striker element adapted to contact the door surround as the door moves into its closed position and thereby disengage the detent means to enable the latch bolts to move into their latched position under the effect of the biassing means.

For preference four latch bolts are provided, one at each edge of the door, and for descriptive convenience the invention is described accordingly hereinafter, but it will be appreciated that one or two of the latch bolts and the corresponding connecting rods may be omitted without departing from the scope of the invention.

In one class of embodiments two horizontally moveable latch bolts are connected to the master crank mechanism, and two vertically moveable latch bolts are connected to the slave crank mechanism. In this class of embodiments, one of the connecting rods extending from the master crank mechanism to the latch bolt at the hinged edge of the door passes over the slave crank mechanism and may serve the double duty of a connecting rod and a component of said linking means.

o In another, more preferred, class of embodiments the master crank 15 mechanism is connected by a connecting rod to one of the latch bolts and is linked by the linkage means to the centrally positioned slave crank mechanism and the slave crank mechanism is connected by three connecting rods to the remaining three latch bolts.

By way of example, an embodiment of the above described invention is described in more detail hereinafter with reference to the accompanying drawings.

Figure 1 is a perspective view from the inside of an external door fitted with a lock, having four latch bolts, according to the invention.

Figure 2 is a rear elevation of the lock appearing in figure 1 with its cover plates removed, parts of its vertically extending components cut away and shown with the latch bolts in their latched positions.

Figure 3 is a view similar to figure 2 showing the lock with the latch bolts in their unlatched positions.

Figure 4 is a plan view of a free edge portion of the door and lock of figure 1 in a nearly closed position.

Figure 5 is a sectional elevation taken on line 5-5 of figure 3.

o *oo Figure 6 is an enlarged, perspective view of an operating shaft and associated shaft mounted components of the lock of figure 1.

oOle 10 The illustrated lock is shown applied to an external door 7 operating within a doorway frame 8. It is key operable from the outside by means of a conventional key 9 coacting with a conventional multiple pin and cylinder lock barrel 10, and manually operable from the inside by means of a rotatable handle 11 on a spindle 12 extending from the 15 barrel 10 to the handle 11.

The lock comprises a backing piece in the nature of a cruciform plate comprising four arms 13, 14, 15 and 16 respectively extending from a central junction 17. Arm 14 comprises two partially overlapping strips 18 and 19 respectively. Strip 18 is longitudinally slotted at 20 and is secured to strip 19 by screws 21 extending through the slots 20. Thus, the strips 19 and 20 are able to be fixed to each other at any desired degree of overlap so that the length of the arm 14 may be adjusted to suit the dimensions of the door to which the mechanism is to be applied. It will be seen from the drawings that arms 13, 15 and 16 are similarly adjustable in length and they need no further description in this respect.

In use, the backing piece may be held by screws or bolts to an inside face of the door 7, with the junction 17 at or near the middle of the door and the arms 13 to 16 extending vertically or horizontally, as the case may be, to, or near to, the respective edges of the door.

The spindle 12 extends through the arm 13 of the backing piece near the end thereof. That spindle is preferably journalled in a bearing element 22 rotatably mounted to the backing piece. Thus, in conventional manner, the spindle 12 extends through the backing piece and engages a :10 connecting tongue 23 of the conventional key operated barrel accessible from the opposite side of the door to that on which the subject lock mechanism is mounted.

handle spindle 12 also extends through a double throw master crank 24 with its throws 1800 apart. That master crank 24 may be 15 generally semi-circular plate with the spindle extending perpendicularly through the mid-point of its straight edge. The crank 24 is either nonrotatably mounted upon the spindle 12 or is integral therewith, and is provided with pivot holes 25 near the ends of its straight edge whereby it may be pivotally connected to a connecting rod 26 and an oppositely directed link rod 27 respectively. The handle spindle 12 may rotate through 900, whereby the rods 26 and 27 are pushed apart to a position where the rods are in near in alignment with the crank's straight edge (as shown in figure or pulled towards each other to a position where they are substantially out of alignment with the straight edge (as shown in figure Each so called rod 26 and 27 may be a length of stout wire or light weight square sectioned tube or other light rigid member and is provided with eyes at each end for pivotal connection to contiguous components.

The link rod 27 extends from the master crank plate 24 to a slave crank disk 30 and is connected thereto by a pivot pin 31 extending from the disk 30 throught the rod 27 or vice versa. Thus the crank disk 30 is caused to rotate in concert with the crank plate 24.

Three further connecting rods 33, 34 and 35 respectively extend from the slave crank disk For preference link rod 27 is in two parts 28 and 29a that may be secured together with various degrees of overlap, or is otherwise rendered length adjustable, to enable the rod length to be adjusted to suit doors of different dimensions.

el The connecting rods 33, 34 and 35 are similarly adjustable in length and need no further description in that respect.

The ends of the connecting rods 26, 33 and 34 remote from the f at crank mechanisms are respectively pivotally connected to flat ended latch bolts 36, 37 and 38 mounted in tubular or other guides 39, 40 and 41, so that rotation of the door handle 11 causes axial projection or retraction of the latch bolts. Connecting rod 35 is similarly connected to a similarly mounted latch bolt not shown in the drawings.

Biassing means, for example, a loading spring 42 urges connecting rod 34 into the position shown in figure 2 whereby latch bolt 38 is urged into the projected position shown in that figure, wherein it projects through an opening in a striker plate 43 secured to the door frame 8. The spring 42 may be assissted by or entirely replaced by a spiral clock spring (not shown) applying a rotational bias upon the crank disk 30 or the crank plate 24. By virtue of the crank mechanisms, latch bolts 36 and 37 are simultaneously urged into there projected positions wherein they engage striker plates 44 and 45 respectively. Likewise the fourth latch bolt is urged into engagement with a fourth striker plate 49.

In accordance with the invention, detent means are provide to hold the latch bolts in their retracted or unlatched positions when the door has been opened. Those means, in this instance, comprise, a push rod 46 including a striker tip 47 projecting axially of the push rod at one end thereof, a loading spring 48 urging the push rod towards said one end, and a rotary sprag 10 When the door is open and the latch bolts are retracted, the loading spring 48, by way of the push rod 46, urges the sprag 50 into engagement with a notch 51 (see figure 2) in the curved periphery of the crank plate 24. In other embodiments the sprag may bear against a step in, or a projectingextending from, the curved edge of the plate 24. In any event, :15 this prevents rotation of the plate 24 against the effect of the biassing S; means and this, in turn, ensures that the latch bolts remain retracted clear of the striker plates 44, 45, 43 and 49. However, if the door is swung olooo shut, for example by operation of a door closer 53, the striker tip 47 contacts an inclined cam face 52 (see Figure 4) on the striker plate 44 causing the push rod 46 to be moved against the effect of the spring 48 so as to disengage the sprag 50 from the crank plate 24 and allow the loading spring 42 to effect projection of the latch bolts into engagement with the openings in the respective striker plates, whereby the door is latched shut.

In other embodiments the striker released detent means may take other forms and may engage other parts of the lock mechanism to hold it against movement until the door is pushed shut.

Claims (7)

1. A door lock mechanism comprising at least one flat ended latch bolt, biassing means urging said latch bolt into a latched position wherein the bolt projects beyond an edge of the door, an operating mechanism including a rotatable handle whereby the latch bolt may be drawn, against the effect of the biassing means, into an unlatched, retracted position, and detent means automatically engaging the operating mechanism or latch bolt when the latch bolt is in the unlatched position to then hold the bolt in the unlatched position; said detent means including a striker element 10 adapted to contact the door surround as the door moves into its closed position and thereby disengage the detent means to enable the latch bolt to move into the latched position under the effect of the biassing means.

2. A multiple latch, door lock mechanism comprising a backing piece adapted to be secured to a surface of a door, a master crank means 15 rotatably mounted on said backing piece adjacent the free edge of the door at or near the mid-point thereof, a manually operable operating mechanism adapted to effect rotation of said master crank, a slave crank means mounted on said backing piece at or near the middle point of said surface, linking means connecting the two crank means such that rotation of the master crank means causes corresponding rotation of the slave crank means, three latch bolts mounted on said backing piece respectively positioned at or near mid-points of associated door edges, a connecting rod extending from said master crank means to one of said latch boltsand at least two connecting rods extending respectively from the other two latch bolts to said slave crank means and effecting projection and retraction of the latch bolts into latched and unlatched positions respectively in response to rotation of the master crank means, biassing means urging said latch bolts into their latched positions, and detent means automatically engaging a said operating mechanism or a said crank means when the latch bolts are in their unlatched positions to then hold the bolts in their unlatched positions; said detent means including a striker element adapted to contact the door surround as the door moves into its closed position and thereby disengage the detent means to enable the latch bolts to move into their latched position under the effect of the biassing means.

3. A door lock mechanism according to claim 2 further comprising a fourth latch bolt connected to said slave crank means by a corresponding 10 fourth connecting rod. o. 4. A door lock mechanism according to either claim 2 or claim 3 further comprising a backing piece adapted to be secured flatly against a i'"o face of a door and comprising a plurality of arms extending radially from a junction, wherein said slave crank means is mounted to said junction, 15 said master crank means is mounted to one of said arms at a position Sspaced from said junction, and said latch bolts are respectively mounted to the arms at or near the ends thereof. 000000 A door lock mechanism according to claim 4 wherein said arms, said connecting rods and said linking means are each length adjustable.

6. A door lock mechanism according to claim 5 wherein each said arm comprises two partially overlapping strips adapted to be fixed together and to said door.

7. A door lock mechanism according to any one of claims 2 to 6 wherein said operating mechanism comprises a rotatable spindle extending through said door and wherein said master crank means comprises a double throw master crank fixed to said spindle.

8. A door lock mechanism according to any one of claims 2 to 7 wherein said detent means comprise a push rod including a striker tip projecting axially of the push rod at one end thereof, a loading spring urging the push rod towards said one end, a movable sprag sprag adapted to engage said operating mechanism or master cam means, an inclined cam face fixed to a doorway surround adjacent an edge of the door when closed that is contacted by the striker tip as the door is closed to move said sprag and free said mechanism or master crank means. 10 9. A door lock mechanism according to claim 8 wherein said master crank comprises a generally circular or part circular plate, and wherein said sprag engages a recess or step in the curved edge of said master crank. A door lock mechanism according to any one of the preceding 15 claims wherein said biassing means comprises a loading spring.

11. A door lock mechanism substantially as described herein with reference to the accompanying drawings. Applicant D. AND V. O'NEILL PTY. LTD. Dated 9 June 1997 Attorney ROBERT G. SHELSTON F.I.P.A.A. of CARTER SMITH BEADLE