BACKGROUND Electromechanical locking devices are known which in- clude electrically interfaced or controlled release mechanisms for operating a lock cylinder. For example, US patent No 5, 839, 307 discloses an electromechanical cylinder lock which includes an cuter lock housing and a rotatable core located therein which is controlled by dual locking features. A plurality of electromechanical locking members in the core with grooves formed therein ac_eFt ã sl-e bar or portions in a non-blocking posi- tien. A magnetic core rotates the electromechanical locking members to a desired position relative to the side bar to allow rotation of the barrel.

. drawback with this prior art locking device is that no mechanical returning of the locking members is pro- vided. This means that the locking members remain in a non-blocking position should the lock be de-energised during operation thereof, thus decreasing the security of the lock. This could be a result of someone removing the battery in the key powering the blocking mechanism.

OBJECTS OF THE INVENTION An object of the present invention is to provide a lock device of the kind initially mentioned in which the electrically controlled blocking mechanism is automati- cally returned to a blocking position when the key is withdrawn from the lock cylinder.

Another object is to provide a lock device, which is more secure than prior art lock devices.

SUMMARY OF THE INVENTION The invention is based on the realisation that the blocking mechanism can be provided with means co-ope-- a--ns w. h a return mechanism during withdrawal of a key from the lock.

Thus, according to the invention there is provided a lock-key combination as defined in claim 1.

A lock-key combination according to the invention is more secure than prior art devices in that mechanical returning c= the blocking mechanism is ensured during withdrawal of the key from the lock.

BRIEF DESCRIPTION OF DRAWINGS The invention is now described, by way of example, with reference to the accompanying drawings, in which : Fig. 1 shows an exploded view of the core of a cylinder lock device according to the invention ; Figs. 2a and 2b are enlarged perspective views of an actuator according to the invention ;

Fig. 3 is an enlarged perspective view of a finger pin co-operating with components shown in figure 1 ; Fig. 4 is a perspective view showing the interaction of the finger pin shown in fig. 3 and a key ; Fig. 5 shows a cross sectional view of the lock device of figure 1 with the blocking mechanism in a non-block- ing position ; Fig. 6 is a view similar to that of figure 5 but with the blocking mechanism in a fully blocking position ; Fig. 7 is a view similar to that of figure 5 but with a side bar in an extended position ; Fig. 8 is a view similar to that of figure 5 but with the blocking mechanism in a blocking position effected by means of withdrawal of the key from the lock ; Fig. 9 is a cross sectional view of the lock device of figure 1 showing indexing of the actuator ; and Figs. lOa-c are a perspective view, a plan view and a cross sectional view of a second embodiment, respec- tively, of a second embodiment of a blocking mechanism according to the invention.

DETAILED DESCRIPTION OF THE INVENTION In the following, a detailed description of preferred embodiments of the invention will be given. In figure 1, an exploded perspective view of a cylinder core according to the invention, generally designated 10, is shown. The core is arranged to be placed in a bore 4 of a conventional cylinder housing 2 (shown in figures 5- s. Thus, the core has an cuter surface substantially

corresponding to the bore of the housing and includes a key-way 12 configured to receive a key as is known in the art. The core 10 includes a plurality of tumbler pin bores 14 that receive tumbler pins, of which one 16 is shown in figure 1. The manner in which a properly bitted key (not shown in figure 1) engages the tumbler pins and positions them to a shear line to permit the core 10 to be rotated with respect to the housing is known in the art and thus will not be described in more detail herein.

Throughout this description, the blocking function of the tumbler pins 16 will be disregarded, assuming that a correctly bitted key has been inserted into the lock.

Thus, when for example it is stated herein that the core is blocked, it is blocked by the electrically con- trolled blocking mechanism.

Mith reference to figures 5-9, the housing 2 includes a cavity 6 in which is positioned a side bar 20 co- operating with the housing either to block or to permit rotation of the core within the housing. The function of a side bar is described for example in the Swedish patent application No 7906022-4, which is incorporated herein by reference. Thus, the wall of the cavity is formed as a camming surface for moving the side bar out of the cavity upon rotation of the core. As can be seen in figure 6, which shows the side bar 20 and an actua- tor 30 (discussed in detail below) in a core rotation blocking position, the side bar is received in the cavity 6 and its inner edge extends beyond the internal surface of the housing bore 4 and engages the housing to prevent the ccre from rotation to operate the lock.

The blocking mechanism will now be described in detail.

Returning to figure 1, the term blocking mechanism will in this description refer to, besides the side bar 20, the elongated actuator 30 with a partly cylindrical en- velope surface and an electric motor 40 with a shaft 46 mechanically coupled to the actuator 30.

The actuator is located radially inward of the side bar 20 in a cylindrical actuator bore 32, see figure 5. The actuator 30 can be rotated by means of the electric motor 40 positioned in the actuator bore 32 and me- chanically connected to the actuator 30. In the pre- ferred embodiment, the connection is effected by means of the motor shaft 46 being shaped like a screwdriver that is, with an end portion with a flat or at least non-circular cross section. The end of the motor shaft 46 is positioned in a corresponding bore 33 in the end surface of the actuator facing the motor, see figure 2a. In that way, the actuator is rotated to- gether with a motor shaft when the motor 40 is ener- gised. in the other end thereof, the actuator 30 is jcurnalled by means of an extending pin 34, see figure 2b, co-operatina with a corresponding bore (not shown) in the actuator bore.

The motor 40 is energised under control of lock elec- tronics 48 electrically connected to the motor by means of wires, see figure 1. The electronics 48 comprises a custom made micro controller with associated memories, driving circuitry etc. and is powered by a battery lo- cated in a key inserted into the lock. To that end, there is provided a key contact 42 in the form of an electrically conducting metal strip shaped so as to

make contact with a contact on the side of the key blade of the inserted key.

Inward of the actuator 30 there is provided a finger pin 50 movable in a direction perpendicular to the centre axis of the cylinder core 10. The finger pin 50 is provided with a cut out portion 52 aligned with the actuator 30, see figure 3, and is spring loaded down- ward as seen in figures 5-9 by means of a helical spring 54 located above the finger pin 50. With no key inserted, the finger pin rests on the actuator 30, as seen in figures 6 and 8, thereby securing it against unwanted rotation. However, the finger pin is lifted by the side code 72 of an inserted key 70, as seen in fig- ures 4, 5 and 7, to an upper end position, in which the rotation of the actuator 3C is not affected.

Finally, to ensure that the side bar 20 engages the side bar cavity 6 when aligned therewith, a yoke shaped positioning element 60 is provided outside of the actuator 30 but inward of the side bar 20, see also figure 3. The positioning element 60 is spring biased radially outward by means cf springs (not shown). Thus, with the side bar 20 aligned with the side bar cavity 4, the spring force applied on the positioning element 60 forces the side bar 20 radially outward and into en- gacement with the walls of the side bar cavity 4. There is also a spring (not shown) provided at the other end of the side bar compared to the positioning element and also functioning to urae the side bar 20 radially out- ward.

The operation of the blocking mechanism including the side bar 20 and the actuator 30 with motor 40 will now be described with reference to figures 5-9.

In figure 5, the blocking mechanism is shown in a non- blocking position, i. e., with an inserted key. The side bar 20 is shown out of alignment with the side bar cav- ity 6 and in a retracted position and the cylinder core 10 is thus free to rotate in the cylinder housing bore.

As is seen in the figures, the actuator 30 is not en- tirely cylindrical. Instead, besides a cylindrical en- velope surface 38, it is provided with a recess 35 and an essentially flat engagement surface 36, see figures 2a and 2b.

In he non-blocking position, the actuator 30 is in the position shown in figure 5. The cut out portion com- prising the recess 35 allows the side bar to be re- fracted within the outer periphery of the core 10 and into the recess 35, thus allowing rotation of the core relative to the housing. The rotation of the actuator 30 to the position shown in figure 5 is effected by means of the motor 40. When a correctly electronically coded key is inserted into the lock, the electronics 43 verifies that a correct key has been inserted and sends control signals to the motor 40 to rotate the actuator.

The normal blocking position of the blocking mechanism will now be described with reference to figure 6. The side bar 20 has now been aligned with the side bar cav- ity 6 and pushed therein by means of the force exerted by the positioning element 60 and the above mentioned spring (not shown) provided at the other end of the

side bar. The actuator has then been rotated approxi- mately 180° counter clockwise compared to the position shown in figure 5. This means that instead of the re- cess 35, the cylindrical envelope surface 38 of the ac- tua or now faces the side bar. In that position, the side bar 20 is prevented from being cammed to within the outer periphery of the core 10, i. e., to within the she-line between the core 10 and the housing 2. The rotational movement of the actuator 30 to the position shown in figure 6 is commanded by the electronics 48 when the key is withdrawn from the lock key-way 12.

This is the normal operation of the blocking mechanism.

However, there are situations in which this normal blocking operation is disabled. An example thereof is when the electronics 48 is de-energised with the key still in the key-way 12. This could be a result of someone removing the battery in the key powering the electronics 48 and the motor 40 or a power failure in case of a wired lock. In a lock according to the inven- tion, there is provided a mechanical back-up returning of the normally electronically controlled blocking mechanism to a blocked position. This emergency return- ina will now be described with reference to figures 7 and 8.

In figure 7, the side bar 20 is shown in engagement with the walls of the side bar cavity 6. This position is obtained when the side bar 20 aligned with the side bar cavity 6 and, as already stated, the positioning element 60 forces the side bar into engagement with the side bar cavity walls. In that position, the side bar does not impede the rotation of the actuator 30.

When being withdrawn from the key-way 12, the key re- leases the finger pin 50 and the spring force exerted by the spring 54 forces the finger pin downward against the actuator 30. During displacement, an engagement surface 56 in the cut out portion 52 of the finger pin 50 engages the engagement surface 36 of the actuator, thereby forcing the actuator to rotate counter clock- wise approximately 60° to the position shown in figure 8. After this rotation, the envelope surface 38 of the actuator faces the side bar 20, thereby blocking the radially inward movement of the side bar. n the position shown in figure 8, the actuator 30 has not been rotated as far away from the non-blocking po- s_ ion shown in figures 5 and 7 as when in the normal blocking position shown in figure 6. However, the in- traction between the engagement surface 36 of the actuator and the engagement surface 56 of the finger pin ensures that the actuator can not accidentally or fraudulently be rotated to a non-blocking position.

The rotation of the actuator 30 is also constrained or indexed by means of a protrusion or pin 22 provided on the side bar 20 and a co-operating indexing groove 39 in the envelope surface of the actuator 30, see figure 2a. The operation thereof appears from figure 9, which is a cross-sectional view of the lock in level with the indexing groove of the actuator. The groove 39 runs approximately 180° degrees around the actuator and the protrusion 22 is guided in that groove during rotation of the actuator. This limits the rotation of the actua- tor to within allowed limits and thus ensures reliable rotation of the actuator.

A second embodiment of a key and lock combination according to the invention will now be described with reference to figures 10a-c. In figure 10a there is shown an actuator 30'of essentially the same shape as the actuator 30 described above with reference to the first embodiment. However, the actuator shown in figure 10a is provided with longitudinal grooves 37 along essentially the entire envelope surface 38'thereof.

The grooves 37 constitute means co-operating with at least one step 24 provided on the side bar 20'. The function of the grooves 37 and the step 24 will now be described with reference to figure 10c, which is a cross sectional view of the actuator 30'and the side bar 20'taken along the lines A-A, see figure lOb.

In the position shown in figure 5, i. e., with the side bar in the side bar cavity 6, the step 24 does not im- pede the rotation of the actuator 30'. However, if someone is trying to rotate the core, e. g. trying to fraudulently open the lock, the side bar 20'is cammed out of the cavity, thereby pressing against the actua- tor 30'. If the actuator is rotated while the core is rotated, the step 24 of the side bar 20'will engage the first groove 37 encountered and be seated therein, thereby preventing further rotation of the actuator 30'.

The provision of the step 24 and the grooves 37 in- creases the security of the lock, making it even harder to effect a fraudulent movement of the actuator from a blocking to a non-blocking position.

Preferred embodiments of a key and lock combination according to the invention have been described. The

person skilled in the art realises that these could be varied within the scope given by the appended claims.

Thus, a motor has been shown powered by a battery pro- vided in the key. It could also be powered by a battery provided in the lock or by an external power source connected to the lock by means of wires.

The actuator has been shown with a specific shape. It is realised that it could have any suitable shape as long as it moves from a non-blocking position (figure 5) to a blocking position (figure 8) under mechanical control when the key is withdrawn from the lock. c.

Although only one finger pin has been shown in the fig- ures, there can be more than one finger pin interacting with an inserted key and the actuator. This finger pin has been shown movable essentially perpendicularly to the axis of the lock cylinder. It is realised that this pin can be movable in other directions as long as the interaction between the pin and the key and the actua- tor, respectively, is provided in a functioning way.

The finger pin has been shown interacting with a side code of the key. The finger pin can also interact with other portions of the key, such as a groove provided on the side of the key blade. It could for example be pro- vided in the form of a guided pin.

REFERENCE NUMERALS 2 Housing 4 Bore 6 Side bar cavity 10 Core 12 Key-way 14 Tumbler pin bores 16 Tumbler pin 20, 20'Side bar 22 Indexing protrusion 24 Step 30, 30'Actuator 32 Actuator bore 33 Driving bore 34 Journalling pin 35 Recess 36 Engagement surface 37 Grooves 38, 38'Envelope surface 39 Indexing groove 40 Motor 42 Key contact 46 Motor shaft 48 Electronics 50 Finger pin 52 Cut out portion 54 Helical spring 56 Engagement surface 60 Positioning element 70 Key 72 Side code