GB1596078A

GB1596078A - Latch bolt lock

Info

Publication number: GB1596078A
Application number: GB21252/78A
Authority: GB
Original assignee: GKN Stenman AB
Current assignee: GKN Stenman AB
Priority date: 1977-05-26
Filing date: 1978-05-22
Publication date: 1981-08-19
Also published as: SE419358B; FI74515C; DK232878A; NO151015B; FI781624A; NO151015C; SE7706219L; NO781777L; FI74515B

Description

(54) IMPROVEMENTS IN OR RELATING TO A LATCH BOLT LOCK (71) We, GKN STENMAN AB, a Swedish Company of P.O. Box 37163105 Eskilstuna, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a lock. It has been proposed to provide a latch which comprises two latch bolts movable in a lock housing, one of the latch bolts being operated by means of a knob or handle the other being automatically movable to a latching position with the aid of a spring.

The spring biassed bolt is capable of being returned, via transmission means, to its released position by means of at least one key-actuated operating means. Locks of this type are known in which the key-operated bolt is arranged to move to its fully locked position when the door is closed, without needing to be actuated by a key.

It will be appreciated that with this type of lock, locking of a bolt is not positively controlled by a key, which can mean in practice that, when closing the door, the bolt will not adopt a fully locked position, for example because free movement of the bolt is prevented as a result of a gap or irregularities between the latch plate and the bolt. Cases are known where a burglar or some other person wishing to break into a building has placed a piece of chewing gum or the like in the latch plate when the door has been open, so that the bolt is unable to extend to its full locking position when the door is closed, thereby preventing the door from being safely locked.The burglar, or other person wishing to make an illegal entrance, can then very easily insert a tool between the door frame and the bolt and move the bolt to its retracted position, thereby obtaining access to the building.

Swedish Patent Specification No. 73 09187-8 describes a dead bolt lock in which it is necessary to turn an associated key by a single complete turn in order to ensure that the dead bolt of the lock extends to its full locking position. Thus, this lock has the advantage over the above described lock in which the bolt is moved to the locking position by a spring, that one can be sure, subsequent to rotating the key one complete turn, that the dead bolt has actually been moved to its full locking position. Due to the fact that the dead bolt is not moved by a spring to its locked position, this lock arrangement, however, has the disadvantage that it is always necessary to use a key in order to ensure that the door is properly locked.With such a lock it is thus always necessary to use a key in order to lock the door, even if one is leaving the building for only a short time.

Examples of previously known locks lacking automatic latching in the position taken by the latch bolt when closing the door or having other of the above mentioned disadvantages are to be found in U.S.A. Patent Specification Nos. 1,007,649, 1,309,300, 1,557,374, 2,121,515, German Patent Specification 369,098 and French Patent Specification No. 1,045,572.

An object of the present invention is to provide a lock in which the above described disadvantages encountered in prior proposed locks are reduced or obviated.

According to this invention there is provided a lock comprising two latch bolts movable in a lock housing, of which bolts one is actuated by a knob or handle and the other of which is automatically movable to a latching position by means of a spring and is retractable to its release position, via transmission means by means of at least one key-actuated operating means, the locking mechanism having a means for releasably holding the spring actuated latch bolt in the automatically adopted latching position, the said latch bolt being movable from said automatically adopted latching position into a safe or security position in which a full locking stroke of the latch bolt is ensured on operating said key actuated operating means.

A lock in accordance with a preferred embodiment of the present invention is a double-function lock which exhibits an automatic locking function for so-called day-locking, i.e. a lock which provides a normally fully satisfactory locking function when a building is left temporarily but which also affords, compared with previously known locks, a considerably increased security against attempts to force an entry when the building is to be left unattended for longer periods of time.

In addition to the automatic locking function, a preferred lock in accordance with the present invention can also ensure positive locking since, subsequent to turning the key, it is impossible to remove the key from the lock unless the bolt has moved through its fully locking stroke.

Expressed in another way, the preferred lock according to the invention ensures that a lock having an automatically latched latch bolt can be locked by rotating a key in a manner such that the lock-when so required-forms a positively controlled safety or dead bolt lock.

It is preferred that rotation of the key causes a special latching means to move to a latching position in which the latching means firstly ensures that the bolt has moved through its fully latching movement and secondly holds the bolt locked in this position.

If when the key is operated, in the preferred lock, the latch means does not adopt its proper latching position, it is not possible to remove the key from the lock, which indicates to the person turning the key that the bolt mechanism has not completed its full locking stroke, for some reason or other.

The arrangement is preferably so constructed that when the bolt moves to its release position, a safety means, e.g. a latch hook, which locks the bolt in the automatically adopted latching position, is moved out of the latching position by means of a special member.

In prior proposed locks of the type generally under discussion a latch hook is often provided which normally holds the latching bolt locked in the automatically adopted locking position. If, however, the bolt does not adopt its fully locking position, the latching hook will not function in the intended manner, and with automatic locks there is no possibility of checkingwhether the hook has functioned in the intended manner or not. This serious disadvantage encountered with hitherto known locks is avoided by the preferred lock in accordance with the invention in that the latch hook, or corresponding means, is brought out of function when locking to a fully position, the latching function being taken over by means whose movement to the latching position is positively controlled under the action of a key.

In a preferred embodiment of a lock in accordance with the invention the bolt is adapted to be positively moved from the automatically adopted latching position, when the key is turned, to a position corresponding to the full latching stroke of the bolt. This positive displacement is preferably effected by means of the movement-transmission means of the lock mechanism.

The automatic latching position can, in practice, correspond to a movement of the bolt of 11-17 mm from the initial retracted position, preferably approximately 14 mm, while a full latching stroke can correspond to a distance of movement of the bolt of 18-24 mm, preferably approximately 21 mm.

In an especially useful embodiment of the lock in accordance with the invention the movement-transmission means comprises an operating means capable of being rotated by a locking cylinder, which operating means, during part of its rotary movement, is arranged to move a preferably rectilinearly movable operating element between different positions. The operating element is arranged to coact with further transmission means, and the operating means is arranged to engage at least three different parts of the operating element, namely one part for displacing the bolt from the automatic latching position to the full latching position, a further part for returning the bolt from the automatic latching position to the released position, and another part for returning the bolt from the full latching position to the automatic latching position.

With a locking mechanism of this type it is possible, with simple means, to provide a double locking function and to move the bolt from its different locking positions to the released position.

In the case of a key-operated latch bolt moved from the automatic latching position to the latching position corresponding to a full locking stroke, it is possible also for the person operating the lock to feel that the bolt has actually executed the intended, special locking movement.

A particularly simple locking mechanism may be provided with a locking mechanism of the aforedescribed type in which the operating element is provided with teeth arranged to co-act with a toothed transmission element rotatably mounted on a shaft, the transmission element having means for actuating a latching hook cooperating with the bolt.

The transmission elements may also have the aforementioned latching means, which is then conveniently in the form of a pin capable of moving in a recess in the bolt and arranged in one position to hold the bolt locked in the latching position corresponding to the full locking stroke.

The said transmission means may be adapted so that the movement of the bolt from the automatically adopted latching position to the position corresponding to the full latching stroke is effected by turning the key through only one revolution.

In one specific preferred embodiment of the invention the holding means comprises a spring which surrounds a pin on the latch bolt and which has bigger spring force than the spring for displacing the latch bolt to the automatically adopted latching position.

In another embodiment the holding means comprises an arm which is pivoted around a pin on the latch bolt and, in the automatically adopted latching position, the arm is prevented from turning by a shoulder on the latch bolt, whereby the latch bolt is kept in the said position. Turning of the key will accomplish pivoting of the arm biased by the spring which has moved the arm and the latch bolt to the said position, whereupon a full stroke of the latch bolt is achieved.

The last mentioned modification has a further advantage that when the latch bolt is moved to its release position by rotating the key a special member on the transmission means will operate the knob or handle actuated latch bolt so that also this latch bolt is simultaneously displaced to its release position.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partially cut away side view of a lock provided with double-latch bolts in accordance with the invention, the upper latch bolt being held latched in the automatically adopted locking position by a latching element, Figure 2 is a view corresponding to that shown in Figure 1 of the upper latch bolt mechanism, the door being assumed to be open, so that the bolt is in its released position, Figure 3 is a view of the upper latch bolt mechanism with the door in the closed position and the bolt moved to the latching position corresponding to a full locking stroke of the bolt by means of a key, Figure 4 is a view similar to Figure 2 illustrating a modified embodiment in which the complete lower latch bolt can be seen, the door being in the open position, so that the latch bar of the lock is not actuated, Figure 5 is a view of the upper and lower latch bolts, respectively, the door being in its closed position and the upper latch bolt being shown as having been displaced, by rotation of the key, to its security of fully locked position, and Figure 6 illustrates the upper and lower latch bolts, respectively, after simultaneous displacemen] to the release position upon rotation of the key, the door being in the open position, with the latch bar not actuated.

The corresponding parts have been given the same reference numerals in Figures 1 to 3 and 4 to 6, respectively. When differences occur, however, the reference numerals in Figures 46 have been provided with a prime sign (').

A latch bolt lock shown in Figures 1 to 3 and having a double-latching or locking function is provided with a lock housing 1 which incorporates a conventional latch bolt 2 having a chamfered surface 2a, the bolt being actuated by a handle or knob (not shown) in a conventional manner.

Above the bolt 2 there is located a further latch bolt 3 having a chamfered surface 3a, said bolt 3 being actuated by a latching mechanism hereinafter described.

Located between the two latch bolts 2, 3 is a latch bar 4.

Located above the upper bolt 3 is a holding latch 5 having a finger-actuated latch means 5a projecting out through an aperture formed in the lock plate 6 and a downwardly extending latch means 5b arranged to co-act with a recess 3b in the bolt 3. The holding latch 5 may be moved up or down by the latch means 5a, and when moved down the means 5b engage recess 3b in a manner such as to enable the bolt to be held trapped in its released position, whereas when the latch is moved up the bolt is released.

The latch bar 4 cooperates with a spring 10 which engages a latching hook 11. When the latching bar 4 is pressed into the lock housing, the latching hook 11 is swung to the latched position and hold the bolt locked against a support plate 25. This occurs when the bolt 3a is located in the position shown in Figure 1, i.e. the latching position automatically adopted by the bolt when the door is closed. The bolt 3a is moved to this position by a drive spring 21 which also counteracts movement of the bolt to the released position.

In a part 14 of the end wall of the lock housing a follower 15 is rotatably mounted which is actuated by the locking cylinder of a cylinder lock in the normal way. The follower has a substantially heart-shaped protruding operating means 15a which, when the cylinder is rotated clockwise or counterclockwise, causes rectilinear displacement of an operating element 16 in respective directions. The operating element 16 is rectilinearly movable, the element 16 moving along agroove 14a in the part 14. The upper part of the operating element 16 has an approximately U-shaped recess which enables the operating means 15a to co-act with three different parts 16a, 16b and 16c of the operating element.

A transmission element 17 which is mounted for pivoted movement about a pin 17a has an arcuate peripheral portion at a constant radius from the pin 17a, this arcuate portion having teeth which engage corresponding teeth 16d of a linear rack provided on the member 16. Thus linear movement of member 16 causes rotational movement of transmission element 17. The transmission element 17 has a pin 17b which, when the bolt 3 moves from the position shown in Figure 1 to the released or retracted position thus rotating the transmission element 17 in a counter clockwise direction, engages the latch hook 11 and moves said hook from its latching position.When the bolt moves from the position shown in Figure 1 to that shown in Figure 3, the locking function is taken over by a pin 18 mounted on the transmission element 17, said pin being movable in a recess 3d in the bolt 3, and upon movement of the bolt through its full locking stroke pin 18 takes the position shown in Figure 3. In this position the bolt is held locked by the latch pin 18. Should for some reason or other, for example a foreign object located in the latch plate, the bolt 3 be unable to take the latching position shown in Figure 3, this will be immediately observed by the person turning the follower 15 by means of the key, since the rotation cannot be completed when the latching pin is not able to adopt the position illustrated in Figure 3.

Thus, the latch pin 18 will ensure that the bolt is moved through its full locking stroke and will hold the bolt locked in this position.

When the operating member 15a is moved clockwise from the position shown in Figure 2, it will engage the surface 16b on the operating element 16, whereupon the operating element moves to the left to an end position (not shown) in which the bolt 3 is withdrawn from the position shown in Figure 2 to the released position.

When the follower 15, and therewith the operating member 15a, is rotated counterclockwise from the position shown in Figure 2, the operating member will engage the part 16a of the operating element, whereupon the operating element is moved to the right to the position shown in Figure 3. The bolt 3 will then take the latching position corresponding to a full locking stroke, shown in Figure 3.

Finally, if the operating member 15a is rotated clockwise from the position shown in Figure 3, the operating member will engage the part 16c on the operating element, whereupon the bolt 3 is withdrawn from the position shown in Figure 3 to the position shown in Figure 1, from where it can be withdrawn to its released position by continued rotation of the operating element 16.

The length of stroke of the bolt at the position shown in Figure 1 and 2 corresponds to approximately 14 mm, while the full locking stroke of the bolt, shown in Figure 3, corresponds to a distance of approximately 21 mm.

In the above described embodiment illustrated in Figures 1 to 3 the latch bolt 3 is kept in the automatically adopted locking position by means of a special member which in this embodiment comprises a spring 20 which surrounds a pin 12 on the latch bolt 3, one end of which engages the front wall of the lock housing in the region of the lock plate 6. When the latch bolt 3 moves to a position in which it protrudes further from the lock housing than when in the automatically adopted locking position the spring 20 exerts a bigger spring force than the spring 21 which is provided to displace the latch bolt to the automatically adopted locking position. When the latch bolt 3 is displaced to the full stroke latching position illustrated in Figure 3 by rotating the key the force of the spring 20 is overcome.When the latch bolt is displaced in this way a certain rocking of the spring 20 takes place so that its upper end takes the position shown in Figure 3.

Thus the latch bolt 3 adopts an automatic locking position, but can be double locked with the aid of a key, the bolt 3 then moving further out of the housing to a full stroke locking position. When a door provided with the lock is closed the latch bolt 3 will enter a hole in a striking plate (not shown) but the latch bar 4 will be displaced into the housing, as shown in Figure 3. In this position the latch bar 4 actuates the latch hook 11 to lock the bolt 3 in position.

In the modified embodiment illustrated in Figures 4 to 6 displacement of the latch bolt 3' to the automatic locking position is also accomplished by means of a spring here denoted 21'. The spring 21' has a very different position to that of the spring 21 and surrounds a pin 27 which passes through a hole in the holding latch 5'.

Further, the latch bolt holding means does not take the form of a spring 20 but comprises an arm 20' which is journalled on a pin 12' on the latch bolt 3'. Thus, the arm 20' holds the latch bolt 3' in the automatically adopted locking position for which purpose the arm 20' coacts with the spring 21'. Further displacement of the latch bolt 3' is prevented by the fact that the arm 20' engages the front wall of the locking housing, i.e. on the inside of the lock plate 6. In this position the arm 20' engages a shoulder 3'f on the latch bolt 3'.

On rotation of the key to accomplish the full stroke locking position of the latch bolt 3' the pin 18', on the transmission means 17' will enter into the recess 3'd in the latch bolt 3' (see Figure 5) and displace the latch bolt until latching is obtained. At the same time the arm 20' is turned clockwise around the pin 12'. During this movement the spring force from the spring 21' is overcome.

On closing a door provided with the lock the latch bolt will enter a hole in a striking plate (not shown) and the latch bar 4' will be displaced into the lock housing. The latch bar 4' releases the latch hook 11' which by being actuated by spring 10'b pivots upwardly to the latching position in which the hook member ill'a engages the recess 3'g in the latch bolt 3'. Then the bolt will be latched in the said position.

When the latch bolt 3', on rotation of the key, is displaced to the released position illustrated in Figure 6 a projection 17'e on the transmission means 17' firstly engages the latch hook 11' and moves it out of the latching position, whereupon the pin 18' on the transmission means on continued rotation, will be actuating a carrier arm 22 cause the lower handle or knob actuated latch bolt 2 to be withdrawn to the release position shown in Figure 6. Thus, both latch bolts 3' and 2 are moved to the release position simultaneously by one and the same turning movement of the key.

The locking mechanism can be actuated from the other side by a further lock cylinder or a knob or the like.

The concept of the invention can also be applied to a lever-tumbler lock, a key bit actuating the bolt either directly or via transmission means.

WHAT WE CLAIM IS: 1. A lock comprising two latch bolts movable in a lock housing, of which bolts one is actuated by a knob or handle and the other of which is automatically movable to a latching position by means of a spring and is retractable to its release position, via transmission means by means of at least one key-actuated operating means, the locking mechanism having a means for releasably holding the spring actuated latch bolt in the automatically adopted latching position, the said latch bolt being movable from said automatically adapted latching position into a safe or security position in which a full locking stroke of the latch bolt is ensured on operating said key actuated operating means.

2. A lock according to claim 1, wherein operation of the key actuated operating means can cause a special latch member to move to a latching position in which the latching member firstly ensures that the bolt has executed a full locking stroke and secondly holds the bolt latched in this position.

3. A lock according to claim 2, wherein when the bolt moves to the free position a member which latches the bolt in the automatically adopted latching position, is brought out of the latching position.

4. A lock according to any one of claims 1 to 3, wherein the bolt is adapted to be positively moved to the position corresponding to the fully locked position from the automatically adopted latching position when the key is rotated.

5. A lock according to claim 4, wherein the positive displacement is effected by means of transmission means associated with the locking mechanism.

6. A lock according to claim 4 or 5 in which the transmission means comprises an operating means which can be rotated by action of the locking cylinder and which during part of its rotary movement is arranged to actuate a rectilinearly movable operating element between different positions, said operating element cooperating with further transmission means, the operating means being arranged to engage at least three different parts of the operating element, namely one part for moving the bolt from the automatic latching position to the position corresponding to a fully locked position, a further part for returning the bolt from the automatic latching position to the released position, and another part for returning the bolt from the position corresponding to a full locking stroke to the automatically adopted position.

7. A lock according to claim 6, in which the operating element is provided with teeth and is arranged to co-act with a toothed transmission means rotatably mounted on a shaft, the transmission element carrying a member for actuating a latching hook coacting with the bolt.

8. A lock according to claim 7, wherein the transmission means has a member arranged for movement in a recess in the bolt and adapted, in one position, to hold the bolt latched in the latching position corresponding to a full locking stroke of the bolt.

9. A lock according to any one of claims 1 to 8, wherein the locking mechanism is adapted, when the key is rotated to one revolution, to ensure that the bolt executes a full locking stroke.

10. A lock according to any one of claims 1 to 9, wherein the automatic latching

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. latch bolt 3' is prevented by the fact that the arm 20' engages the front wall of the locking housing, i.e. on the inside of the lock plate 6. In this position the arm 20' engages a shoulder 3'f on the latch bolt 3'. On rotation of the key to accomplish the full stroke locking position of the latch bolt 3' the pin 18', on the transmission means 17' will enter into the recess 3'd in the latch bolt 3' (see Figure 5) and displace the latch bolt until latching is obtained. At the same time the arm 20' is turned clockwise around the pin 12'. During this movement the spring force from the spring 21' is overcome. On closing a door provided with the lock the latch bolt will enter a hole in a striking plate (not shown) and the latch bar 4' will be displaced into the lock housing. The latch bar 4' releases the latch hook 11' which by being actuated by spring 10'b pivots upwardly to the latching position in which the hook member ill'a engages the recess 3'g in the latch bolt 3'. Then the bolt will be latched in the said position. When the latch bolt 3', on rotation of the key, is displaced to the released position illustrated in Figure 6 a projection 17'e on the transmission means 17' firstly engages the latch hook 11' and moves it out of the latching position, whereupon the pin 18' on the transmission means on continued rotation, will be actuating a carrier arm 22 cause the lower handle or knob actuated latch bolt 2 to be withdrawn to the release position shown in Figure 6. Thus, both latch bolts 3' and 2 are moved to the release position simultaneously by one and the same turning movement of the key. The locking mechanism can be actuated from the other side by a further lock cylinder or a knob or the like. The concept of the invention can also be applied to a lever-tumbler lock, a key bit actuating the bolt either directly or via transmission means. WHAT WE CLAIM IS:

1. A lock comprising two latch bolts movable in a lock housing, of which bolts one is actuated by a knob or handle and the other of which is automatically movable to a latching position by means of a spring and is retractable to its release position, via transmission means by means of at least one key-actuated operating means, the locking mechanism having a means for releasably holding the spring actuated latch bolt in the automatically adopted latching position, the said latch bolt being movable from said automatically adapted latching position into a safe or security position in which a full locking stroke of the latch bolt is ensured on operating said key actuated operating means.

position corresponds to a length of movement of the bolt of 11-17 mm.

11. A lock according to any one of claims 1 to 10, wherein the safety position of the bolt corresponds to a length of movement of the bolt of 18-24 mm.

12. A lock according to any one of claims 1 to 11, wherein the holding means comprises a spring surrounding a pin on the latch bolt and having bigger spring force than the spring for displacing the latch bolt to the automatically adopted latching position.

13. A lock according to any one of claims 1 to 11, wherein the holding means comprises an armjournalled on a pin on the latch bolt, said arm, in the automatically adopted latching position, being prevented from pivoting by engaging a shoulder on the latch bolt, the latch bolt then being retained in the said position, whereas turning of the key accomplishes pivoting of the arm biased by the spring having moved the latch bolt and the arm to the said position, so that movement of the latch bolt to the full-stroke latching position is accomplished.

14. A lock according to claim 13 as dependant upon claim 8, wherein the transmission means has a further member which, when turning of the key accomplishes displacement of the latch bolt to the release position actuates a carrier member which simultaneously displaces the knob or handle actuated latch bolt to the release position.

15. A lock substantially as herein described with reference to and as shown in Figures 1 to 3 of the accompanying drawings.

16. A lock substantially as herein described with reference to and as shown in Figures 4 to 6 of the accompanying drawings.