Field of the invention The invention relates to a locking device comprising a forend, a lock housing or lock case disposed on the forend and having a locking mechanism, and at least one lock bolt, which is mechanically coupled to the locking mechanism and is movable between a position retracted into the lock case and a position extended through a bolt opening made in the forend. The invention is especially advantageous in locking devices which are intended for mortise-type or recessed fitting on a door, hatch, gate or the like.

Background of the invention

Locking devices of this kind are usually found, for example, in mechanical locks in exterior doors to houses. Typically the lock is of the mortise type. The locking mechanism can be coupled to a lock cylinder and a handle on the outer side of the door for operating one or more lock bolts which are each movable between a positioned retracted into the lock case and a position extended through the forend, in which extended position they engage with a striking plate in the door frame. Depending on the type of lock and the field of application, the lock bolts can be of different type. Examples of lock bolts which can form part of a lock having such a locking device are spring bolts, linearly displaceable bolts, swing bolts, hook bolts and rolling bolts. Common to these lock bolts is that, in their extended position, they extend through a bolt opening in the forend.

In order to allow good mobility with low friction of the lock bolt, the bolt opening for a particular lock bolt is usually configured with somewhat larger cross- sectional dimensions than the lock bolt, so that the lock bolt, in its extended position, is accommodated in the bolt opening with a clearance. In this way, a gap is formed between the lock bolt and the bolt opening. When the lock bolt is centred in the bolt opening, the gap extends around the lock bolt. Typically, the cross section of the lock bolt, as well as the bolt opening, are polygonal, usually rectangular, but it also occurs that one or more of the sides of the lock bolt and lock opening are curved, in which case the gap along the sides of the lock bolt acquires a corresponding shape. Due to the gravitational effect upon the lock bolt, it occurs that the lock bolt, in its extended state, bears against the forend, at the lower part of the bolt opening, in which case the gap, when the lock bolt has a rectangular cross section, extends along three of the sides of the lock bolt. Furthermore, the fastening of the lock bolt and its coupling to the locking mechanism can be configured with a certain clearance or play such that the lock bolt is movable in its lateral directions. It is hence possible to make the gap on one side of the lock bolt larger than the gap on the opposite side, by pressing the lock bolt against this opposite side. In modern locks having a locking device of this kind, the clearance between the lock bolt and the forend at the bolt opening, in the cross-sectional plane of the lock bolt, is usually between about 0.3 and 0.5 mm .

A problem with such known locking devices is that the clearance between the lock bolts and the forend at the respective bolt opening allows the insertion of a thin object into the gap which, due to the clearance, can be formed on either side of the lock bolt. By inserting a thin object of this kind through the gap, it may in certain cases be possible for an unauthorized person to manipulate or damage the locking mechanism in the lock case. This problem is especially great with outward- opening, rebated doors, in which a door chink, accessible from the outside, is formed between the forend and the striking plate . Summary of the invention

One object of the invention, is to provide an improved locking device of the type defined in the introduction. A particular object is to provide a locking device of this kind which offers higher security and in which the risk of unauthorized manipulation of the lock is reduced.

These and other objects are obtained with a locking device of the type which is defined in the preamble to Patent Claim 1 and which has the special technical features defined in the characterizing part of the claim.

The locking device according to the invention comprises a forend having at least one bolt opening, a lock case disposed at the forend and having a locking mechanism, and at least one lock bolt, which is mechanically coupled to the locking mechanism and is movable between a position retracted into the lock case and a position extended through the bolt opening. The lock bolt, in its extended position, is accommodated - in the bolt opening with a clearance to the forend. According to the invention, at least one blocking member is disposed in the lock case. When the lock bolt is in its extended position, the blocking member is in contact with a side of the lock bolt running parallel with the motional direction of the lock bolt and extends in a direction away from the said side, inside the forend.

Since the blocking member is in contact with one side of the lock bolt, it is arranged in line with the gap inside the forend. The blocking member thus covers the gap which can be formed on one side of the lock bolt. If a thin, for example leaf-shaped object is inserted into the gap, the object will butt against the blocking member. Hence, either the object is completely blocked from being inserted further into the lock case, or else the object is guided out, away from the side of the lock bolt, towards the walls of the lock case. Access to the components of the locking mechanism, for manipulation of or damage to these components, is thereby made substantially more difficult. With the blocking member according to the invention, a locking device offering substantially higher security than was previously possible is therefore obtained in a simple manner .

The blocking member can comprise a flange, which is fixed relative to the lock case and which bears against said side of the lock bolt running parallel with the motional direction of the lock bolt. In this embodiment, the blocking member is fixed relative to the lock case and is expediently disposed close to the forend, with the lock bolt moving relative to the blocking member. This allows a relatively simple construction, which can be used together with existing lock bolts and in which, therefore, such existing lock bolts can be used without remodelling.

The flange is expediently elastic and pretensioned in a direction towards said side of the lock bolt running parallel with the motional direction of the lock bolt. It is thereby made yet more difficult for a thin object to be able to be pressed in between the blocking member and the lock bolt.

The side of the lock bolt running parallel with the motional direction of the lock bolt expediently has a depression or recess in which the flange is snugly accommodated when the lock bolt is in its extended position. This embodiment, too, makes the insertion of an object between the blocking member and the lock bolt yet more difficult and contributes to the object, even under great insertion force, being guided out towards the walls of the lock case. In order further to increase the security, the blocking member can comprise two flanges disposed one inside the other, which flanges are fixed relative to the lock case and bear against said side of the lock bolt running parallel with the motional direction of the lock bolt.

Instead of being fixed to the lock case, the blocking member can be fixed to the lock bolt. In this embodiment, the blocking member therefore moves with the lock bolt so as to assume its blocking position inside and close to the bolt opening when the lock bolt moves into its extended position. This embodiment is space-saving and requires little or no remodelling of existing lock cases. This embodiment also allows a high level of security, since a thin, for example leaf- shaped object cannot be pressed in between the blocking member and the lock bolt unless the blocking member is broken loose from the lock bolt.

Where the blocking member is fixed to the lock bolt, it can either constitute a separate part which has been fixed to the lock bolt, or can be configured in one piece with at least a part of the lock bolt.

The locking device can also comprise at least a first blocking member, such as a flange, which is fixed relative to the lock case, and at least a second blocking member, which is fixed relative to the lock bolt. A combination of the two types of blocking member is thereby obtained, which combination is advantageous from the security aspect.

The locking device is expediently designed for mortise- type fitting in a door or the like. The side of the lock bolt running parallel with the motional direction of the lock bolt, i.e. the side against which the blocking member is in contact, is in this case expediently constituted by at least one of the sides of — O —

the lock bolt, which runs substantially parallel with the plane of the door leaf. When the locking device is fitted to a door, the gaps between the forend and the lock bolt which run parallel with the door leaf are also parallel with the door chink when the door is closed. These gaps, and especially that which is closest to the outer side of the door, are particularly prone to manipulation through the insertion of a leaf- shaped object, since such an object can be inserted through both the door chink and this gap by simply being bent . By arranging the blocking member according to the invention such that it bears against preferably the outer one of the sides of the lock bolt running parallel with the door leaf, the security is thus substantially improved at the gap between the lock bolt and forend, which in previously known locking devices is most prone to manipulation attempts.

Further advantages and characteristics of the locking device according to the invention emerge from the following detailed description of illustrative embodiments and from the claims.

Detailed description of the figures A description of exemplary embodiments of the invention is given below with reference to the figures, whereof:

Fig. 1 is a perspective view of a first embodiment of a locking device according to the invention.

Fig. 2 is a perspective view corresponding to that in Fig. 1, with certain components removed.

Fig. 3 is a plan view from above, which shows certain parts of the embodiment shown in Fig. 1. Fig. 4 is a plan view corresponding to that in Fig. 3 and shows a second embodiment .

Fig. 5 is a schematic side view of certain parts forming part of the embodiment shown in Fig.

4.

Fig. 6 is a perspective view of the parts shown in

Fig. 5.

Fig. 7 is a perspective view obliquely from behind, which shows certain parts of the locking device according to a third embodiment .

Fig. 8 is a plan view from above of the embodiment shown in Fig . 7.

Fig. 9 is a perspective view, partly in cross section, and shows certain parts forming part of a fourth embodiment.

Detailed description of illustrative embodiments That embodiment of the locking device according to the invention which is shown in Figs. 1-3 is configured for mortise-type fitting in a door leaf. The locking device comprises a forend 1, to which a lock case 2 having a first and a second side wall 3 is fixed. As can most clearly be seen from Figs. 2 and 3, the locking device comprises a U- iron Ia, which is fixed to the forend 1 and to which the side walls 3 of the lock case are fixed. The lock case 2 accommodates a locking mechanism, which, inter alia, comprises a cylinder follower 4 and a handle follower 5 for operation of the locking mechanism. A spring bolt 6 is coupled to the locking mechanism and is axially movable in a straight line through a spring bolt opening 7 which is made through the forend 1. A swing bolt 9 is also coupled to the locking mechanism and is pivotably movable through a bolt opening IQ in the form of a rectangular swing bolt opening which is made in the forend 1. A corresponding bolt opening 10a is also made in the U-iron Ia. The swing bolt 9 is movable between a position retracted into the lock case and the extended position shown in Figs. 1-3. The cross section of that portion of the swing bolt 9 which in the extended position is accommodated in the bolt opening 10 is rectangular. The bolt opening 10 has a corresponding rectangular shape, the height and width of which are somewhat greater than the height and width of the aforesaid cross section of the swing bolt 9. The clearance between the swing bolt 9 and the bolt openings 10, 10a is about 0.1-0.5 mm in the vertical and lateral directions.

According to the invention and as can be seen from Fig. 3, the locking device further comprises a first 20 and a second 30 blocking member. Each blocking member 20, 30 comprises a fixing portion 21, 31, with which the blocking member is fixed to the U- iron Ia forming part of the lock case. Each of the two blocking members 20, 30 also comprises a first, outer 22, 32 and a second, inner 23, 33 elastic flange. Both flanges 22, 32, 23, 33 are connected to a respective fixing portion 21, 31 by means of a joint 24, 34. As can be seen from Fig. 3, the two blocking members 20, 30 rest against the inner side of the U-iron Ia, so that the flanges 22, 23, 32, 33, under pretension, bear against and are pressed against the respective side faces 9a, 9b of the swing bolt 9. As is also evident from Fig. 3, the flanges bear against the side faces of the swing bolt close to and immediately inside the bolt openings 10, 10a in the forend 1 and the U-iron Ia. The flanges 22, 23, 32, 33 are thus in contact with the side faces of the swing bolt 9 and extend in the direction outwards from these. The side faces run parallel with the motional direction of the swing bolt, and hence with the outer side and inner side of the door leaf to which the locking device is intended to be fitted. The blocking members 20, 30, and especially the flanges 22, 23, 32, 33, are expediently made of an elastic polymer material having a customized and relatively high modulus of elasticity. In the case of the embodiment shown in Fig. 3, in which a blocking member is disposed on each side of the swing bolt 9, the two fixing portions 21, 31 can expediently be connected such that the two blocking members constitute parts of an integrated unit, which expediently is configured in one piece, for example by injection moulding.

Fig. 3 illustrates how a gap Sl, S2 is configured on each side of the swing bolt 9, between the swing bolt and the U-iron Ia. The gaps Sl and S2 extend further in through the forend 1, where they are formed by the clearance between the side faces of the swing bolt 9 and the bolt opening 10. The swing bolt 9 is coupled to the locking mechanism with a certain clearance or play, so that the swing bolt 9 can be moved somewhat in the lateral direction. By applying a laterally directed force, for example upwards in Fig. 3, to the swing bolt 9, it is possible to press this into contact against the forend 1 and the U-iron Ia, on one side of the respective bolt opening 10, 10a. The gap S2 on the opposite side, i.e. the lower side in Fig. 3, can thereby be widened around the swing bolt, so that this gap acquires a width substantially corresponding to the total clearance between the forend 1 or the U- iron Ia and the swing bolt 9, at the bolt openings 10, 10a.

If a leaf-shaped object or the like is inserted through the gap S2 so as thereby to manipulate or damage the locking mechanism in the lock case, the object will butt against the outer flange 32. The object will then be guided outwards towards the inner side of the U- iron, i.e. downwards in Fig. 3. It is thereby made substantially more difficult for the object to be inserted sufficiently far into the lock case that it reaches the moving parts of the locking mechanism for manipulation thereof. Even if the object can nevertheless be passed between the outer flange 32 and the swing bolt 9, the object, in contact with the inner flange 33, will be obstructed by the inner flange 33. The inner flange 33 has a thinner point and a more acute contact angle to the side face of the swing bolt 10 than does the outer flange 33. If an object is inserted from the gap S2 to the inner flange 33, the object will be guided out onto the outer side of the flange. The contact force of the flange against the swing bolt will hence increase further, the higher the insertion force which can be applied to the object. A self-locking effect is hereby achieved, which makes it yet more difficult to insert an object as far as the moving and vital parts of the locking mechanism.

In Figs. 4-6, a somewhat modified embodiment is illustrated. In this embodiment, a recess or depression 91, 92 is made on each side face of the swing bolt 9. The depressions 91, 92 are constituted by elongated channels, which extend substantially parallel with the forend, immediately inside this, when the swing bolt is in its extended position. The depressions 91, 92 are further arranged relative to the blocking members 20, 30 such that the inner flanges 23, 33 are accommodated in the respective depression and bear there against the swing bolt 9 when this is in its extended position. By virtue of the depressions, it is made yet more difficult for a leaf-shaped object which is inserted along one of the side faces of the swing bolt 9 towards the inner flanges 23, 33 to be able to pass between these flanges and the swing bolt 9.

In Figs . 7 and 8 , a further embodiment of the locking device according to the invention is illustrated. In this embodiment, the blocking members 20', 30' are fixed to the swing bolt instead of to the lock case. In - li ¬

the embodiment shown in Figs . 7 and 8 , the blocking members 20', 30' are configured as bars projecting from the side faces of the swing bolt 9' . The blocking members are here configured in one piece with the swing bolt 9' , but it is also possible to configure similar bar-shaped blocking members as separate parts which are fixed to the swing bolt, for example by gluing or otherwise. The blocking members 20', 30' are elongated and extend substantially parallel with the forend 1 when the swing bolt is in its extended position. The blocking members are made, furthermore, of a rigid and high-strength material, which, where the blocking members are configured in one piece with the swing bolt, is typically a metal material such as steel. If a thin object is inserted through one of the gaps Sl or S2 , the object will butt against the stop formed by that side of the projecting blocking member which is facing the gap. The object is hereupon blocked from further passage into the lock case. The object can possibly be made to slide outwards towards the side walls of the lock case along that side of the blocking member 20', 30' which is facing the gap Sl, S2. In this case, the object will however be guided in the direction of the inner side of the U-iron and will be wedged there between the blocking member 20', 30' and the inner side of the U-iron Ia.

Especially in this latter described embodiment, but also in the previously described embodiments, it is advantageous if the projecting bars 20', 30' and the flanges 22, 23, 32, 33 are arranged close to the forend when the swing bolt is in its extended position. The closer to the forend and the gap Sl, S2 that the projecting bars 20', 30' and the flanges 22, 23, 32, 33 are placed, the harder it becomes to make a thin object, inserted through the gap Sl, S2, bend such that it can pass outside the projecting bars 20', 30' and the flanges 22, 23, 32, 33 and onward between these and the inner side of the U- iron. The distance between the projecting bars 20', 30' and flanges 22, 23, 32, 33 and the bolt opening 10a, 10 in the U- iron, or, in the absence of such a U-iron, in the forend 1, is expediently between about 0 and 25 mm. It is thus possible, and in certain cases advantageous, if at least one blocking member bears against the forend or the U- iron so that the blocking member sealingly covers the gap around the lock bolt. In other applications and especially where the blocking member comprises a flange, it may be advantageous if the flange is arranged at a certain minimum distance from the forend, since a yet more difficult manoeuvring of the thin leaf-shaped manipulation object is then required in order to guide this in between the flange and the lock bolt.

Fig. 9 illustrates a further embodiment of the invention. In this embodiment, two different blocking members are combined, which are fixed to the swing bolt and to the lock case respectively. In the embodiment shown in Fig. 9, the swing bolt 9'' is configured with two different cross-sectional widths, so that that portion 95'' of the swing bolt which in the extended position passes out through the bolt openings 10, 10a in the forend 1 and the U-iron Ia has a smaller cross- sectional width than the portion 96' ' which is constantly located in the lock case inside the bolt openings. The transition between the narrower portion 95'' and the wider portion 96'' forms a step-shaped stop on both sides of the swing bolt. These stops each form, together with the wider portion of the swing bolt 9' ' inside the stops, a respective blocking member 20'', 30'', which thus is fixed to and constitutes an integral part of the swing bolt 9'' . This embodiment also comprises blocking members, which are fixed to the U-iron of the lock case. These blocking members are constituted by flanges 22'', 32'', which correspond to the outer flanges 22, 23 shown in Fig. 3. The flanges 22'', 32'' bear under pretension against the respective side face of the swing bolt 9'', at the narrow portion 95'', between the bolt opening 10a of the U-iron and the blocking members 20'', 30'' configured as stops, when the swing bolt is in the extended position. With this embodiment, a combined blocking effect with both elastic flanges and butt stops is therefore obtained, which makes it yet more difficult to insert a thin object as far as the moving and vital parts of the locking mechanism.

In an unshown embodiment, the locking device comprises the blocking members 20'', 30'' shown in Fig. 9, configured as stops on a swing bolt having two different cross-sectional widths, but lacks the flange- shaped blocking members which, in the embodiment shown in Fig. 9, are fixed to the U-iron.

Above, exemplary embodiments of the invention have been described. It will be appreciated that this description shall not be considered limiting for the invention, but that the invention can freely be modified within the scope of the following claims. For example, all illustrative embodiments above comprise a swing bolt. It will be appreciated, however, that the invention is also eminently suitable for locking devices which comprise other lock bolts than specifically swing bolts. Examples of such lock bolts which are movable through a bolt opening in a forend and which can advantageously be provided with blocking members according to the invention are linearly and axially movable bolts, wedge bolts, spring bolts, locking bolts and combined latches and bolts which usually go under the name latch bolts. The examples above further show how blocking members are disposed on both the sides of the swing bolt which are vertical when the locking device is fitted in a door leaf. In many cases, it may however be sufficient to dispose blocking members only on that vertical side of the lock bolt which is facing the outer side of the door. This therefore increases the security against manipulation of the locking device from the outside of the door when the door is closed and locked. It is especially advantageous, as described above, to dispose blocking members specifically on one or both sides of the swing bolt, which, when the locking device is mounted in a door, run parallel with the outer side and inner side of the door leaf. This since it might otherwise be possible, by bending about just one axis of a thin, for example leaf-shaped object, to insert this object both through the door chink and through a vertical gap on the side of the lock bolt. In order to realize the insertion of a leaf- shaped object of this kind firstly through the door chink and subsequently through a horizontal gap between the lock bolt and the forend, the leaf-shaped object is required to be both bent about a first axis and rotated about a second axis, which axes are at right angles to each other. Even though this is difficult to carry out in practice, one or more blocking members can also or alternatively be disposed in a covering arrangement inside such a horizontal gap between the lock bolt and the forend.