GB2143572A - A lock for use both as a latch and a deadlock for a door - Google Patents

Abstract

A door lock has a single latchbolt 2 slidably mounted in a housing 1, the latch bolt 2 being operative as a latch and also as a 12 deadlock. The latchbolt 2 is held in an intermediate latching position as the door is closed and automatically moves to a position beyond the latching position deadlocking the door, in response to the inward movement caused by door closure. The bolt is held in the deadlocking position against inward movement. <IMAGE>

Description

SPECIFICATION A lock for use both as a latch and a deadlock for a door This invention relates to a lock for use both as a latch and a deadlock for a door.

In U.S. Patent 4,255,953 there is described a combined latch and deadlock for a door, in which a latch can be moved from its usual latching position, to protrude further from the lock to provide a deadlock. Deadlocking of the lock is selected by operation of a key or a knob on the lock.

In U.S. Patent 4,124,238 a latchbolt mechanism is described in which a door latch is automatically caused to protrude beyond its normal latching position in response to closure of the door. The mechanism includes an auxiliary latchbolt which senses when the closure of the door occurs, and causes the main latch bolt to protrude beyond its normal latching position. However, the mechanism has the disadvantage that it requires an auxiliary latchbolt to sense door closure. Also, the mechanism does not hold the main latchbolt against inward movement in the deadlock position.

According to the present invention there is provided a lock for use both as a latch and as a deadlock for a door, comprising a housing, a latchbolt protruding from the housing and mounted for inward and subsequent outward movement in response to closure of the door to permit latching of the door, and means responsive to said inward movement of the latchbolt, for automatically holding the latchbolt in a deadlock position in which the latchbolt is prevented from inward movement.

More particularly, the invention provides a lock for use both as a latch and a deadlock for a door, comprising a housing, a latchbolt arranged in a latching position thereof to protrude from the housing by a relatively small amount, the latchbolt being movable inwardly of the housing from the latching position to permit latching of the door, control means operative in response to said inward movement to urge the latchbolt to protrude from the housing by a relatively larger amount, and means for holding the latchbolt when so extended in a deadlock position in which it is prevented from inward movement.

In order that the invention may be more fully understood an embodiment thereof will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a partial sectional view of a lock in accordance with the invention, with the latch bolt in its latching position prior to closure of the door; Figure 2 illustrates the lock of Figure 1 as the latch bolt 2 is urged inwardly by engagement with a striker plate, as the door is closed; Figure 3 illustrates the lock with the latchbolt having moved automatically to its deadlocked position; and Figure 4 illustrates release of the lock.

Referring to Figure 1, the lock comprises a cast metal housing 1 in which a latchbolt 2 is slidably received. In the usual way, the lock is mounted on the inside of a door (not shown) and the latchbolt is received in an aperture 3 in a striker plate 4 (Fig. 3) on a door frame, so as to latch and lock the door. The latchbolt 2 has a rectangular sectioned portion 2a protruding from the lock housing 1, the portion 2a including an inclined surface 5 to facilitate latching of the door and entry of the portion 2a into the aperture 3 when the door is pushed to a closed position.

The latchbolt 2 is typically made of brass.

In order to improve the security afforded by the latchbolt, it includes a hard steel rolling pin 6 received within a bore aligned with the sliding direction of the bolt 2. The pin 6 is mounted for axial rotation within the bolt 2 so that if an attempt is made to saw through the latchbolt 2, the pin will rotate with the saw movement, making it very difficult to cut through the bolt.

Figures 1 to 3 show the sequence of events that occur when the door is pushed closed.

Figure 1 shows the configuration of the lock when the door is open. The protruding portion 2a of the latchbolt extends by a relatively small amount from the housing 1 to define a latching position for the bolt 2, in which the inclined surface 5 is configured to cooperate with the striker plate 4 to latch the door.

Referring now to Figure 2, as the door is pushed to its closed position, the inclined surface 5 of the latchbolt 2 engages the striker plate 4 and consequently the latch bolt 2 is urged inwardly of the housing 1.

When the door is pushed fully closed, as is shown in Figure 3, the mechanism of the lock urges the latch bolt 2 outwardly of the housing, through the aperture 3 in the striker plate 4, such that the latchbolt 2 protrudes by a relatively large amount to define a deadlock position. When in the deadlock position, the latchbolt 2 cannot be moved back into the lock housing 1 by the application of force to the protruding latch bolt portion 2a, thus preventing the lock being forced by items such as screwdrivers or credit cards inserted between the door and the frame. Also, because the latch bolt protrudes from the housing 1 by a relatively large amount, the inclined surface 5 is moved deep into the striker plate 4 so that an implement cannot be inserted between the door and the frame and urged against the surface 5 to force the lock.

Thus, the lock operates as a latch when the door is pushed closed, and the latchbolt thereafter automatically moves to a deadlock position in response to the inward movement of the latch bolt that occurs when the door is latched.

The mechanism which achieves the automatic deadlocking will now be described. The latch bolt 2 is attached to a latchbolt plate 2b and is urged outwardly of the housing 1 by a spring 7 to protrude through an aperture in a side wall 1 a of the housing. The plate 2b includes a slot 8 to enable it to slide back and forth relative to a tubular rotary shaft 9 mounted in the housing 1, the rotational axis of the shaft 9 extending transversely of the plate 2b.

The shaft 9 is urged to rotate anticlockwise by a coaxially disposed coil spring 10. First and second cams 11, 1 2 are mounted for rotation with the shaft 9. The first cam 11 has a cam surface 11 a which cooperates with a deadlocking post 13 on the plate 2b to hold the latch bolt 2 in its deadlocked position.

Also, the cam 11 has a cam surface 11 b that cooperates with an unlocking post 14 on the plate 2b for withdrawing the latchbolt 2 into the housing 1. The second cam 1 2 has a cam surface 1 2a which upon clockwise rotation engages surface 15a of a catch arm 1 5 pivotally mounted by a screw 1 6 on the housing 1. The arm 1 5 is urged in a clockwise direction by a spring 17.

A control plate 1 8 is constrained to slide in a plane parallel to a major surface of the latchbolt plate 2b. The control plate 1 8 includes a rectilinear slot 19, which slidably receives a control post 20 mounted on the latchbolt plate 2b, the slot 1 9 extending generally in the direction of sliding motion of the latchbolt 2. The control plate 1 8 includes another slot 21 which receives a guide post 22 fixedly mounted on the housing 1. The slot 21 includes a first portion 21 a extending parallel to the slot 1 9 and a second portion 21 b extending transversely of the first portion.

A spring 23 mounted on a peg 24 on the housing 1, urges the plate 1 8 towards the side wall 1 a cf the housing. The control plate 18 is formed with a rectangular lug 25 for engaging a rectangular step 26 in the edge of latchbolt plate 2b. A shoulder 27 on the control plate 18 is arranged to slide over a shoulder 28 on the catch arm 1 5, to be caught in a detent 29.

When the latchbolt 2 is in its latching position as shown in Figure 1, the control plate 1 8 is urged by spring 23 to a first position in abutment with the side wall 1 a of the housing, so that the lug 25 assumes a position to engage the step 26 in the edge of the latchbolt plate 2b. Consequentially, the spring 7 cannot urge the latchbolt 2 any further out of the housing than the latching position.

However, as shown in Figure 2, when the door is pushed closed, the latchbolt 2 engages the striker plate 4 and slides inwardly against the force of the spring 7. The latchbolt plate 2b thus moves to the left as shown in Figure 2 so that the control post 20 engages the left hand end of the slot 1 9 in the control plate 18, pulling the control plate 18 to the left to assume a second position. As the plate 1 8 moves to the left, the transverse slot portion 21 b cooperates with the fixed guide post 22 to move the control plate 1 8 transversely of the slide direction of the latchbolt plate 2b, in an outward direction so as to move the lug 25 clear of the step 26.The shoulder 27 slides past the shoulder 28 and the catch arm 1 5 is urged counterclockwise by spring 1 7 so that the shoulder 27 is captured in the detent 29, and the control plate 1 8 is held by the catch arm.

The latch bolt 2 can now move to the deadlock position as shown in Figure 3. The control plate 1 8 is now held in its second position by the catch arm 15, with the lug 25 clear of the step 26, so that when the latchbolt 2 becomes aligned with the aperture 3 in the striker plate 4, the latch bolt is moved by the spring 7 fully outwardly to the deadlock position, the step 26 on the plate 2b thus moving past the lug 25. Also, the outward movement of the deadlocking post 1 3 permits the cam 11 and hence the shaft 9 to rotate counterclockwise under the influence of the coil spring 10. The shaft 9 rotates until the cam 1 2 engages the peg 24, as shown in Figure 3.The cam 11 is then in a position to cooperate with the deadlocking post 1 3 to prevent inward sliding movement of the latchbolt 2.

The lock is released from the deadlocked position of Figure 3 by rotating the shaft 9 clockwise, either by means of a handle (not shown) attached to the shaft on the inside of the door, or by turning a key in a barrel lock (not shown) on the outside of the door. The barrel lock has a rectangular section shaft which drivingly engages the shaft 9.

When the shaft 9 is rotated clockwise, the lock assumes the configuration shown in Figure 4. The cam 11 is rotated from engagement with the deadlocking post 1 3 into camming engagement with the unlocking post 14 on the plate 2b, so as to slide the plate 6 and the latchbolt 2 back into the housing 1.

Also, the cam 12 is rotated intocamming engagement with the catch arm 1 5 to rotate arm 1 5 counterclockwise and release the shoulder 27 of the control plate 18. When the shaft 9 is released after such clockwise rotation, the latchbolt 2 returns to the latching position shown in Figure 1.

The release of the control plate 1 8 from the catch arm 1 5 enables the control plate to move to the right under the action of spring 23, and the transverse slot portion 21 b cooperates with the guide post 22 to move the lug 25 inwardly to engage the step 26 in the plate 2 b so as to restrict the outward movement of the latchbolt 2 such that it assumes the latching position shown in Figure 1.

Thus, in accordance with the invention, automatic deadlocking of the latchbolt 2 is achieved in response to closure of the door, by means of a mechanism which responds to the inward movement of the latchbolt that occurs when the door is closed. The lock according to the invention has the advantage that only a single latchbolt is required, and no auxiliary latchbolt is needed to sense closure of the door.

Claims (14)

1. A lock for use both as a latch and as a deadlock for a door, comprising a housing, a latchbolt protruding from the housing and mounted for inward and subsequent outward movement in response to closure of the door to permit latching of the door, and means responsive to said inward movement of the latchbolt, for automatically holding the latchbolt in a deadlock position in which the latchbolt is prevented 'from inward movement.

2. A lock according to claim 1 including cam means urged by spring means to rotate to a position to hold the latchbolt in the deadlock position.

3. A lock for use both as a latch and a deadlock for a door, comprising a housing, a latch bolt arranged in a latching position thereof to protrude from the housing by a relatively small amount, the latchbolt being movable inwardly of the housing from the latching position to permit latching of the door, control means operative in response to said inward movement to urge the latch bolt to protrude from the housing by a relatively larger amount, and means for holding the latchbolt when so extended in a deadlock position in which it is prevented from inward movement.

4. A lock according to claim 3 wherein the control means includes a control member movable to a first position for restricting outward movement of the latchbolt so as to establish the latching position thereof, the control member being arranged to be moved in response to said inward latchbolt movement to a second position wherein the latchbolt is released to move to the deadlock position, and catch means arranged to hold said control member in the second position thereof in response to said inward latch bolt movement.

5. A lock according to claim 4 including means for returning the latchbolt from the deadlock position to the latching position thereof, comprising means for releasing said holding means, means for moving the latchbolt into the housing, and means for releasing the catch means such as to cause the control member to move from the second to the first position thereof, whereby upon subsequent outward movement of the latchbolt the movement thereof is restricted by the control member so as to assume the latching position.

6. A lock according to claim 5 wherein said returning means comprises a rotary shaft having first and second cams mounted thereon, the latch bolt having associated therewith a deadlocking member and a cammable unlocking member, the shaft being urged by spring means to rotate the first camming means to a position to cooperate with the deadlocking member to hold the latch bolt in said deadlocked position,' and the first camming means being arranged to cammingly engage the unlocking member to move the latchbolt inwardly of the housing when the shaft is rotated from said position of cooperation with the deadlock member, said second cam being arranged to release said catch means when the shaft is rotated from said position of cooperation with the deadlock member.

7. A lock according to claim 6 wherein the latchbolt is mounted to slide relative to said housing in a direction transverse to the axis of rotation of the shaft, and the control member comprises a control plate including a slot portion which receives a control post mounted on the latchbolt, the control post being arranged to urge the control plate from the first to the second position thereof in response to said inward movement of the latchbolt.

8. A lock according to claim 7, wherein the control plate includes a lug and the latchbolt includes a stepped edge region so arranged that when the control plate is in said first position the lug engages the stepped edge region to maintain the latchbolt in the latching position thereof.

9. A lock according to claim 8 wherein the control plate includes a further slot portion extending transversely of the latchbolt sliding direction and receiving a guide post mounted on the housing, said further slot portion being so arranged that upon said inward movement of the latchbolt, the control plate moves to the second position thereof in such a manner that the lug moves in a direction transversely of said sliding direction and clear of said stepped edge region to allow the latch bolt subsequently to assume said deadlocked position.

10. A lock according to any one of claims 7 to 9 wherein said catch means includes a catch arm pivotally mounted on the housing and urged by spring means to engage the control plate.

11. A lock according to claim 10 wherein the control plate and the catch arm are formed with a cooperating shoulder and detent to hold the control plate in said second position.

1 2. A lock according to any preceding claim including an elongate member having a cylindric periphery extending longitudinally in the directi of movement of the latch bolt, within the latchbolt, for rotation about the longitudinal axis thereof.

1 3. A lock comprising a housing, a single latch bolt arranged in a latching position thereof to protrude from the housing by a relatively small amount, the latchbolt being movable inwardly of the housing from the latching position to permit latching of the door, control means operative solely in response to said inward movement of said single latch bolt to urge it to protrude from the housing by a relatively larger amount.

14. A lock substantially as hereinbefore described with reference to the accompanying drawings.