TECHNICAL FIELD The present invention relates to a locking device comprising a locking bolt, a spring bolt, a lock communicating member arranged to communicate with a lock, and a handle attachment member arranged for attaching a handle or knob to the locking device for actuation of the spring bolt. PRIOR ART

Locking devices for restricting access to an area or space are known in the art. Locking devices usually comprises one or more locking elements in the form of bolts for denying the opening of a closing element, such as a door, lid, window, hatch or similar, which bolts are controlled by actuation of a lock requiring a key, key code, or similar to be operated.

One example of such a lock and locking device is shown in patent document GB 1 ,221 ,413 showing a night lock comprising only one bolt extendable in a locking position and retractable in an unlocked position. The bolt may be retracted by actuation of either an inner door handle or by actuation with a key.

One common form of a locking device is shown in patent document US 6,651 ,466, in which the locking device comprises a dead bolt, which is actuated by the lock, and a latch bolt, which is actuated by use of a door handle. By including both a dead bolt and a latch bolt the door may be held closed by the latch bolt even if the lock is presently unlocked and the dead bolt is retracted. In US 6,651 ,466, the locking device is further designed so that, when the locking device is locked, both the dead bolt and the latch bolt are retractable by depressing the inner handle, while a blocking member blocks the outer handle from being operated. Another example of this form of locking device is shown in patent document CA 218,504, showing a lock system comprising both a latch bolt and a dead bolt, in which the turning of a key withdraws both the latch bolt and the dead bolt simultaneously, so that the door may be opened by using only one hand. Patent document GB 2,459,493 discloses an emergency handle designed to withdraw both a latch bolt and any additional bolts when operated by a user, wherein the door may be opened from the inside even without a key, and even if the lock is presently locked. One problem with locking devices is that a user may sometimes wish to test whether a lock in a locking device comprising both a dead bolt and a latch bolt, is locked or not. The user then operates the door handle in order to sense if it is possible to open the door. If the door is locked the door may move so that when the user releases the door handle the latch bolt cannot resume its previous, latching position. It may then be that the dead bolt becomes strained in an associated door jamb or strike plate. Due to the applied strain and increased factional force the locking bolt is then difficult to move, so that a greater force is needed to retract the locking bolt. Normally during an unlocking operation, the user recognizes this fact and simply nudges the door to release the strain. In case of an emergency, however, a user may act irrationally so that the user may forget about manually moving the door. Additionally, panic-stricken people may lean against the door, so that it is difficult to release the strain on the dead bolt. The dead bolt may then become stuck so that the user is unable to unlock the dead bolt. In a worst case scenario the locking device may break due to the strong force exerted by the user on the emergency handle, so that it then becomes impossible to unlock the bolt, with dire consequences as a result. SUMMARY OF THE INVENTION

One objective of the present invention is to indicate a new type of locking device which decreases the risk that a locking bolt becomes strained and difficult to move.

According to a first aspect of the invention this objective is achieved with the locking device described in claim 1. The locking device comprises a preventing arrangement designed to prevent actuation of a spring bolt by operation of an inner handle or knob when a lock in the lock communicating member is in a locked state. Thus, when a user operates the inner handle to test if a lock is unlocked, and when the lock is locked, the spring bolt is prevented from being retracted, so that the closing element is less prone to move into a position in which the locking bolt becomes strained. Hence the case with a user being unable to unlock the locking device due to a strained locking bolt is at least partially avoided.

The locking bolt may become strained by one of its sides being pressed towards a wall surface or edge inside a hollow in a door jamb, and/or a strike plate. The pressure towards the wall or edge creates higher frictional forces so that it becomes difficult to retract the locking bolt. If the spring bolt is allowed to retract during a test as described above, movement of the door may cause the spring bolt to become misaligned with its associated hollow or strike plate, so that the spring bolt fails to extend and latch the door, wherein the door remains misaligned and the locking bolt remains under strain.

Preferably the locking device comprises at least one locking bolt, here also named a first bolt, at least one spring bolt, here also named a second bolt, a lock communicating member arranged to communicate with a lock and to actuate the locking bolt based on influence from the lock, a handle attachment member arranged for attaching at least an inner handle or knob to the locking device and a transmission arrangement designed to transfer action from operation of the handle or knob to the spring bolt for actuating the state of the spring bolt. The locking bolt is preferably operable to extend or retract only through operation of the lock in the lock communicating member. The lock per se may or may not be included in the locking device.

Preferably, the preventing arrangement is designed to prevent actuation of the spring bolt by operation of both the inner handle and of an outer handle. Hence the security of the locking device is enhanced in combination with increased safety. Preferably, the preventing arrangement is designed to prevent actuation of the spring bolt when both the locking bolt and the spring bolt are extended. Preferably the preventing arrangement is designed to continue to allow actuation of the spring bolt in case the spring bolt is retracted. Thus the spring bolt may still be extended again, even if someone locks the lock while the spring bolt is retracted. Preferably, once the spring bolt has been extended, the spring bolt is then prevented from being actuated. An inner handle or knob is here considered the handle or knob intended to face inwardly into the space to which access is restricted.

According to one embodiment the preventing arrangement is designed to receive a mechanical action from the lock communicating member when the lock shifts from an unlocked to a locked state, and to forward the mechanical action to actuate a movable preventing member for preventing actuation of the spring bolt. Hence, there is less need for arranging electrical devices inside the locking device for achieving the purpose of the invention, wherein the locking device is less vulnerable to disruptions in electrical supply. Preferably, the preventing arrangement is correspondingly designed to receive a mechanical action from the lock communicating member when the lock shifts from the locked to the unlocked state, and to forward the mechanical action to actuate the movable preventing member for allowing actuation of the spring bolt by operation of the handle or knob. Preferably the lock communicating member is adapted and/ or arranged to hold a mechanical lock. In another embodiment however, the lock communicating member may be adapted and/ or arranged to hold an electric lock.

According to one embodiment the preventing arrangement is designed to prevent actuation of the spring bolt by disengaging the transmission arrangement, if a lock in the lock communication member is in its locked state. Preferably the preventing arrangement is also arranged to reengage the transmission arrangement if a lock in the lock communicating member becomes unlocked. In one embodiment the transmission arrangement comprises at least two transmission links for transferring the action from an operation of the handle or knob to the spring bolt, and the preventing arrangement is designed to engage and disengage the two transmission links from each other based on the state of the lock. Preferably, one of the transmission links is movable in response to the operation of the handle, wherein the preventing arrangement prevents transfer of the movement to the other link when the locking bolt is in its extended, locked state.

By disengaging the transmission arrangement the action from operation of the handle will be less likely to damage the locking device. In another example however the preventing arrangement may instead be arranged to block the transmission arrangement by absorbing the action. In this case however, the preventing member is subjected to more wear, and also, a user may believe that the handle is stuck rather than blocked, and may be prone to use an even higher force on the handle leading to even more wear and possibly breaking of the locking device.

According to one embodiment the preventing arrangement is designed to mechanically disconnect the two links from each other if a lock in the lock communicating member is in a locked state. Preferably, the preventing arrangement is also designed to mechanically connect the two links with each other if a lock in the lock communicating member is in an unlocked state. By disconnecting the transmission arrangement the handle will still be movable while the transmission arrangement is prevented from transmitting the action or force from the handle attachment member to the spring bolt. Hence a user exerting a strong force on the handle will be less prone to damage the locking device or to be able to force the locking device to open than if a blocking mechanism had been used. This is due to that there is no opposing force from a blocking element counteracting the force from the user, which otherwise could mechanically deform the link. According to one embodiment the preventing arrangement comprises a moveable preventing member arranged to form a mechanical connection between the two transmission links through the preventing member when the lock is in an unlocked state. Preferably, the preventing member is designed to form the mechanical connection by conveying a force through the preventing member and between the two transmission links. Preferably, an action force from operation of the handle or knob is transferrable through the mechanically connection, from one of the transmission links to the other transmission link, so that the transmission links co-moves. Preferably, the preventing member is arranged to move out of forming the mechanical connection between the two transmission links when the lock is in a locked state. According to one embodiment the preventing member comprises a pin moveably arranged to engage both a first cavity in the first transmission link and a second cavity in the second transmission link when the lock is in an unlocked state. Hence the pin forms a mechanical connection between the transmission links and conveys a force via the pin from one transmission link to the other in order for the transmission links to co-move.

According to one embodiment the preventing arrangement is designed to move the transmission links into contact with each other to enable a transfer of a mechanical action between the links when a lock in the lock communication member is in an unlocked state, and to move the transmission links apart to disable transfer of a mechanical action between the transmission links if a lock in the lock communicating member is in a locked state. According to one embodiment the lock communicating member comprises a coupling member displaceable between a first and a second position based on the state of the lock, and the preventing arrangement is designed to receive motion from displacement of the coupling member. Hence the lock communicating member undergoes a mechanical change based on the state of the lock, which is transferred to the preventing arrangement. Preferably the lock communicating member is arranged to receive the mechanical motion from the lock. Thus there is no need for any electrically driven components in the locking device. Preferably, the preventing arrangement comprises a preventing member arranged to influence the transmission arrangement based on its current position, wherein the preventing arrangement and the coupling member are designed so that a displacement of the coupling member displaces the position of the preventing member. According to one embodiment the preventing arrangement comprises an elongated guide member connected between the coupling member and the preventing member for forwarding the displacement to the preventing member. Preferably the elongated guide is thin relative to its length, and more preferably the elongated guide also has a small cross-section relative to its length. The elongated guide member is arranged to forward the displacement across a long distance, substantially equal to the length of the elongated guide member, while occupying a small space within the locking device. The elongated guide member is preferably designed having a rod-shaped part arranged in a direction from the lock communicating member towards the transmission arrangement.

According to one embodiment the preventing arrangement and the coupling member are designed so that a rotational displacement of the coupling member is transformed into a linear displacement of the elongated guide member. Hence the elongated member may move a large distance while only demanding a small space for effecting the movement.

According to one embodiment the elongated guide member comprises an elongated rod and a projecting element extending from the rod and being connected with the preventing member. Preferably the projecting element extends at an angle, preferably between 45-135 ^° , more preferably between 75- 105°, relative the length direction of the rod. Hence it is possible to position the elongated rod towards the rim or circumference of the locking device, while being arranged to displace a preventing member arranged within the middle part of the locking device. Preferably the elongated rod and projecting element form an L-shaped guide.

According to one embodiment the lock communicating member is arranged to hold a lock cylinder. Preferably the lock communicating member is arranged to displace the coupling member based on a rotation of the lock cylinder. Lock cylinders are purely mechanical devices which are actuated with keys, wherein there is less risk of failure due to electricity supply issues. According to one embodiment the locking device comprises an emergency bar and an emergency arrangement, wherein actuation of the emergency bar influences the emergency arrangement to simultaneously retract both the locking bolt and the spring bolt. Hence a user may retract both bolts and open the door from the inside in case of an emergency, even without keys. Due to that the spring bolt cannot be retracted while the locking bolt is in its extended, locking state and the lock in the lock communicating member is locked, there is less risk that the locking bolt has ended in a strained position. According to one embodiment the locking device comprises a mortise lock. Mortise locks are known to comprise both a locking bolt and a spring bolt for enhanced functionality of the locking device. The mortise lock preferably comprises a lock housing, or lock box, shaped with a length, width and depth, wherein the length is longer than the depth, which in turn is longer than the width. The lock housing is preferably arranged such that the length and width defines a face plate having holes through which the bolts may extend and retract. The lock housing is preferably shaped to be arranged inside a leaflet of a door, such that the length is arranged vertically, and the face plate is arranged towards a door jamb or strike plate when the door is closed. BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

The invention is now to be described as a number of non-limiting examples of the invention and with reference to the attached drawings.

Fig. la shows a locking device in a first, locking state according to a first example of the invention.

Fig. lb shows the locking device in fig. la in an unlocked state.

Fig. lc shows the locking device of figs, la and lb mounted inside a door.

Fig. Id shows a more detailed view of a preventing member arranged to form a mechanical connection between two transmission links according to one example of the invention.

Fig. 2a shows a locking device in a first, locking state according to a second example of the invention.

Fig. 2b shows the locking device in fig. 2a in an unlocked state.

Fig. 2c shows the locking device in fig. 2a and 2b mounted inside a door.

Fig. 2d shows a more detailed view of the preventing arrangement.

DETAILED DESCRIPTION

In figs, la-d and figs. 2a-d two different examples of locking devices according to the invention are shown. For the sake of simplicity, like elements in the two examples are given the same reference numbers. It should be noted that a man skilled in the art can easily include additional features and functions described in other known or future documents or designs in combination with the present invention. In this example the locking devices are of a mortise lock type, wherein the locking devices are shaped to be positioned inside a door leaflet.

Both locking devices comprise at least one locking bolt 1 , and at least one spring bolt 3. Even though only one bolt of each type is shown in the examples, in practice, any number of locking bolts and/ or spring bolts may be provided. The locking bolt 1 is in these examples a dead bolt arranged to deny opening of a closing element 5 in the form of a door, by being extended into a hollow or opening in a jamb or strike plate in a locked state. The locking bolt is furthermore retractable into an unlocked position, preferably by operation of a lock, wherein the door may be opened. The spring bolt 3 is in these examples a latch bolt. The spring bolt 3 comprises a spring 7 urging the spring bolt towards an extended, latching position. Preferably, the spring bolt comprises a bevelled surface, wherein, upon closing the door, the bevelled surface hits an edge or wall of the strike plate or door jamb, so that the spring bolt is forced towards the retracted position to allow automatic closing of the door without the need of operating a handle.

The locking devices further comprise a lock communicating member 9 arranged to hold and communicate with a lock. The lock communicating member 9 is further arranged to actuate the locking bolt 1 based on influence from the lock through a locking bolt actuation mechanism 1 1 for the locking bolt. The locking devices further comprise a handle attachment member 13 arranged for attaching at least an inner handle or knob 15 to the locking device, and a transmission arrangement 17 designed to transfer action from operation of the handle or knob 15 to the spring bolt 3 for actuating the state of the spring bolt. Several different designs for lock communication members, actuation mechanisms, handle attachment members, and transmission arrangements as described above are commonly known in the art and almost any of the known or future designs may easily be adapted to function with the invention by a man of ordinary skill in the art. Further description of these features is therefore not included here. In figs, la-d and 2a-d the locking devices each comprise a preventing arrangement 19 designed to prevent actuation of the spring bolt 3 by operation of the inner handle 15 if the lock in the lock communicating member is locked, that is, when the locking bolt 1 is in its extended, locked state. The preventing arrangement 19 is also designed to simultaneously prevent actuation of the spring bolt 3 by operation of an outer handle 21. Hence, while the door is locked, the preventing arrangement 19 prevents a user from retracting the spring bolt 3 to its non-latching position by operation of any handle. This gives three advantages in the event that the user intends to test whether the door is locked. Firstly, the user will be informed of that the door is locked from noticing that it is not possible to retract the spring bolt, and therefore, the user is less prone to pull or push on the door at all, which otherwise could lead to the locking bolt ending in a strained state. Secondly, even if the user do push or pull the door, the spring bolt will remain in its latching position so that both the spring bolt and the dead bolt keep the door in place, so that it is less probable that the locking bolt will end up in a strained position. Yet a third effect is that since the user cannot retract the spring bolt, the spring bolt itself cannot become stuck in a retracted position due to displacement of the door, which in turn further decreases the risk of the locking bolt becoming strained. Hence by incorporating the principles of the invention in a locking device it is more likely that the locking bolt may easily be retracted without undue friction in case of an unlocking operation and/ or during an emergency situation. Turning to the specific example in figs, la-d it is shown that the lock communicating member 9 is arranged to hold a lock cylinder 23. A lock cylinder is a mechanical lock comprising a cylinder arranged to be turned by a user with a key 25. The lock communicating member 9 comprises a coupling member 27 displaceable between a first and a second position based on the state of the lock. In this example the lock communicating member 9 comprises a cylindrical element rotatable with rotation of the lock cylinder, wherein the coupling member 27 is connected with and rotates with the cylindrical element. In this example the preventing arrangement 19 is designed to receive a mechanical action from the lock communicating member 9 when the lock shifts from an unlocked to a locked state. In this example the preventing arrangement 19 is further designed to receive the action from displacement of the coupling member 27. Hence the locking device and the lock are driven with a force provided by the user and are completely mechanical, wherein there are fewer issues with security and safety dependent on for example electric supply.

The preventing arrangement 19 is further arranged to forward the mechanical action to actuate a movable preventing member 29 arranged to prevent actuation of the spring bolt 3. The movable preventing member 29 is in turn arranged to influence the transmission arrangement 17 based on its current position. The preventing arrangement 19 and the coupling member 27 are thus designed so that a displacement of the coupling member 27 displaces the position of the preventing member 29. In this example the preventing arrangement 19 comprises an elongated guide member 31 connected between the coupling member 27 and the preventing member 29 for forwarding the displacement of the coupling member 27 to the preventing member 29. The preventing arrangement 19 and the coupling member 27 are designed so that a rotational displacement of the coupling member is transformed into a linear displacement of the elongated guide member 31. In this example the elongated guide member comprises an elongated rod 33, having a cross- sectional area being much smaller than the length of the rod, in this example in a ratio of at least smaller than or equal to 1 : 10, wherein the space requirements for the guide member are small in relation to the distance between the lock communicating member and the preventing member.

The preventing arrangement 19 further comprises a projecting element 35 extending from the rod 33 and which is connected with the preventing member 29. The projecting element 35 is elongated and extends at an angle relative to the length direction of the rod. The projecting element 35 hence makes it possible to arrange the preventing member 29 at a distance from the elongated guide member 31. Thus a greater degree of freedom is allowed for the design of other parts of the locking device, wherein for example, other elements than the guide member may be positioned close to the preventing member, if desired. This is advantageous since the preventing member 29 will most likely, as it is in this example, be positioned close to the middle of the locking device, where the space is limited. In this example the preventing arrangement 19 is designed to prevent actuation of the spring bolt 3 by disengaging the transmission arrangement 17 from transferring an action to the spring bolt. In this example the transmission arrangement comprises a first 37 and a second transmission links 39 (shown in closer detail in fig. Id) arranged for transferring a mechanical action from operation of the door handle to the spring bolt 3, wherein the preventing arrangement 19 is designed to engage and disengage the transmission links 37, 39 from each other based on the state of the lock. In this example the preventing arrangement 19 is furthermore arranged to mechanically disconnect the two transmission links 37, 39 from each other, if the lock in the lock communicating member is in a locked state.

In this example the first transmission link 37 comprises a ring-shaped link connected with the handle attachment member 13 and arranged to rotate with a movement of the door handle. The second transmission link 39 comprises a ring shaped link arranged outside, and to encircle, the first transmission link 37. The first and second links are each further provided with a cavity 41 , 43 arranged to receive the moveable preventing member 29. In this example the preventing member comprises a pin arranged to move in and out of the cavities. In an engaging state, the preventing member 29 is arranged to reside in both cavities 41 , 43 and to extend across the distance between the first and second links, in order to form a mechanical connection between the two links. A movement from operation of a handle in the handle attachment member hence moves the first link 37, and the movement is transferred to the second link 39 via the preventing member 29. In a disengaging state, the pin is moved out of at least one, and preferably both of, the cavities 41 , 43, wherein the links are mechanically disconnected so that a movement of the first link will not be transferred to the second link. In operation, in case the lock in the lock communicating member is locked the elongated guide 31 is moved downwardly in the figure (shown in fig. la). In this example the preventing arrangement 19 comprises a spring 45 arranged to force the moveable preventing member 29 outwards from the cavities and into a disengaging state to mechanically disconnect the transmission links 37, 39. Thus, when a user operates the handle, only the inner, first link 37 will move without transferring its motion to the outer, second link 39. Due to the spring 45 and the absence of the preventing member 29 inside the cavities 41 , 43 the transmission arrangement 17 is prevented from transferring the action from the handle to the spring bolt 3.

In case the lock in the lock communication member is unlocked the elongated guide 31 is moved upwardly so that the projecting element 33 pushes the preventing member 29 into the cavities 41, 43, so as to form the mechanical connection between the two transmission links 37, 39. Hence, the preventing member is actively being pressed towards an engaging state by the preventing arrangement 19. When a user operates a door handle the movement will thus be forwarded through the transmission arrangement 17 from the first link 37 to the second link 39 via the preventing member 29, so that the first and second links co-move with each other. The preventing arrangement 19 further comprises a blocking element 47 arranged outside and around the second link 39, and at a distance from the second link 29, which is shaped to counteract the action from the spring 45 and block the preventing member 29 from moving out of the cavities. When the links are rotated the preventing member 29 follows the links in their rotation, wherein the preventing member 29 is no longer in contact with the projecting element 35. The blocking element 47 thus provides a force holding the preventing member 29 inside the cavities 41 , 43. In this example the transmission arrangement 17 further comprises a force transmission member 49 for forwarding any action from the handle towards the spring bolt 3. The force transmission member 49 is in this example connected with the spring bolt in one end and is connected with the second link 39 with another end. When the second link rotates the force transmission member 49 is moved, so that the end connected with the spring bolt forces the spring bolt to retract with a linear motion. When the door handle is released the force from the spring 7 similarly is transferred via the transmission arrangement 17 to force the door handle to move back into its non-operated position. The locking bolt actuation mechanism 1 1 similarly comprises a force transmission member 51 , which is attached with the locking bolt 1 with one end and with the lock communicating member with its other end, for retracting and extending the locking bolt. The designs of such additional members or parts of the transmission arrangement and locking actuation mechanism are known in the art, and may in practice be nearly arbitrarily selected from known and /or future designs. The transmission arrangement and locking bolt actuation mechanism are therefore not further described here. Naturally, the first, second and any additional links or members may for example be arranged with any suitable shape, and need not be neither ring-shaped, nor move with a rotating motion. For example, the links may be linear and may move with a linear motion, or may be linear and move with a rotating motion, or any combinations thereof.

The locking device may further comprise an emergency handle and an emergency arrangement, wherein actuation of the emergency handle influences the emergency arrangement to simultaneously retract both the locking bolt and the spring bolt. The design of the emergency handle and arrangement may be according to any design known in the art, such as the design shown in GB2459493.

In figs. 2a-d another example of a locking device according to the invention is shown. The lock communication member 9 is in this example arranged to communicate with an electronic lock unit 53 comprising an electronic card reader for reading a magnetic card 55, a wireless chip or similar. The lock communication member comprises an electric motor or solenoid 57 arranged to receive power from the electronic lock through an electric wire 59, and to generate the motion for extending and retracting the locking bolt 1 . The advantage of using an electric lock 53 is that the user need not provide the kinetic energy themselves for opening the lock, and furthermore, the electronically controlled lock may provide additional functions, such as time logging, remote opening etc.

In this example the transmission arrangement 17 comprises a first link 61 connected with the handle attachment member 13, and a second link 63 arranged to forward any motion to the spring bolt, in this case through an additional force transmission member as described in the previous example. In this example the first 61 and second links 63 are shaped as two half- rings, designed to form a joint ring in a connected state. When the links are joined together any movement of the first link 61 is immediately transferred to the second link 63, wherein actuation of the handle may operate the spring bolt.

The preventing arrangement 19 comprises in this example a spring 65 arranged to force the first 61 and second links 63 away from each other so as to disconnect the first and second links, and a movable preventing member 73 arranged to control the position of the second link 63, by either pressing, or by avoiding to press, onto the second link 63. When the lock signals that it is in a locked state, the preventing arrangement 19 is arranged to disengage the transmission arrangement by moving away from the links 61 , 63, so that the spring 65 forces the first and second links apart. Hence, the first link is unable to transfer any motion to the second link, preventing actuation of the spring bolt. When the lock signals that it is in an unlocked state, the preventing member 73 urges the second link 63 to move in connection with the first link 61 , against the force of the spring, wherein a movement may be transferred between the links. The preventing member 73 is in this example shaped as a half-circle, and it is thus ensured that the preventing member 73 holds the first and second links together throughout the entire movement of the links. The preventing arrangement 19 further comprises an elongated guide comprising an elongated rod 67 which is arranged to move the preventing member 73 between its preventing and non-preventing states based on the state of the lock. The lock communicating member 9 comprises a coupling member 69 displaceable between a first and a second position based on the state of the lock 53. The coupling member 69 is connected with and moves the guide member 67. The preventing arrangement 19 further comprises a projecting element 71 connected between the preventing member 73 and the elongated rod 67, for transferring the motion to the preventing member 73.

It should be understood that the scope of the invention is not limited to the devices shown in the examples, and may be varied and altered freely by a man skilled in the art. In particular, the number, shape and detailed design of the various members, links and elements shown in the examples may be changed as long as their basic functionality according to the invention as defined in the following claims remain.