BACKGROUND A cylinder lock comprises a central plug or core and an outer shell or housing, in which the core rotates. The housing is mounted in a suitable latch structure. A num- ber of prior art disclosures describe devices intended to provide a removable core in a cylinder lock. The advantage of removable core locks is that they may be rapidly re-keyed by relatively unskilled personnel. Such re-keying may be required as a result of a potential security breach or occurring due to the loss or non- return of a key.

The patent publication US 6,076, 386 (Etchells et. al.) describes a removable core lock wherein a restraining member in the form of a ball is provided in a concentric groove formed onto a core housing. A drawback with that solution is the lack of code related blocking mechanism for the removal of the core.

A removable core lock for cars is disclosed in the patent publication US 2,036, 764, wherein the connection between the core and an adapter actuating the lock oper- ating means is in the form of a bayonet joint releasable without tools. In order to operate the lock, a long user key engaging a groove in the adapter must be used to rotate not only the core but also the adapter. In order

to disengage the core from the adapter, a short key is used, whereby the core is rotated 90 degrees relatively to the adapter in a specified direction.

While this latter solution provides for a simple design, it is accompanied by several drawbacks. Firstly, the rotation of the adapter relies on the strength of the key tip, resulting in an unreliable operation. Secondly, this lock is relatively easy to manipulate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a removable core lock wherein the drawbacks of prior art devices are eliminated or at least mitigated.

The invention is based on the realization that engage- ment elements can be used for selectively engage and disengage the rotation of a core relatively to an adapter in a removable core lock.

According to the invention there is provided a removable core lock and key device as defined in claim 1 and a service key as defined in claim 9.

With the inventive device the above-mentioned drawbacks of prior art are eliminated or at least mitigated. The lock device according to the present invention as de- fined by the appended claims has a configuration wherein means of connection are provided to axially interlock the core and an adapter operatively connected to a bolt, and wherein engagement elements are provided to allow or prevent the means of connection to be disengaged.

In a particularly preferred embodiment, the engagement elements comprise a radially moveable side bar in the core and a recess in an aperture in an adapter opera- tively connected to a bolt. The side bar provides a secure way of preventing rotation of the core relatively to the adapter. In a further preferred embodiment, a bayonet joint is used as the means of connection to pre- vent withdrawal of the core from the cylinder housing, providing a robust arrangement.

Further preferred features are defined in the dependent claims.

BRIEF DESCRIPTION OF DRAWINGS The invention is now described, by way of example, with reference to the accompanying drawings, in which: fig. 1 is an overall exploded view of a lock device according to the invention; figs. 2 and 3 are perspective views of the lock device in fig. 1 with a core removed from a cylinder housing; fig. 4 is a perspective view of the lock device with inserted core; fig. 5 is a detailed view of the core in figs. 2 and 3; fig. 6 is a detailed view of an adapter part with attached bolt; fig. 7 is a top sectional view of the lock device ; figs. 8 and 9 are side views of a user key and a service key, respectively, for use with the lock device;

fig. 10a is an elevation sectional view of the lock device with inserted user key; figs. 10b and 10c are views taken along the lines Xb-Xb and Xc-Xc, respectively, showing an inserted user key co-operating with a blocking pin; and figs. lla-c are views similar to figs. 10a-c but showing the use of a service key instead of a user key.

DETAILED DESCRIPTION OF THE INVENTION In the following a detailed description of a preferred embodiment of the present invention will be given. In fig. 1 there is shown an exploded view showing the parts comprised in a lock device according to the invention. A cylinder housing 10 is provided with a substantially circular cavity 10a arranged to accommodate a substan- tially circular cylinder core, generally designated 20.

The core has a key way 20a arranged to receive a key 21, as is conventional. Two outer side bars 22a, 22b are arranged in a respective longitudinal groove 20b in the core, one of which being visible in fig. 1. Push pins 23 and springs 24 are provided for biasing the side bars radially outwardly and into engagement with a respective longitudinal groove 10b in the inner surface of the cav- ity 10a, one of which grooves being visible in fig. 1. A side bar arrangement of the above kind is described for example in the international patent publication WO 93/12314 (Haggstrom), which is incorporated herein by reference.

At the inner end thereof, the core 20 is provided with a semi-circular extension 20c having a groove 20d formed

therein, see fig. 5. The function of this protruding portion will be explained below with reference to figs.

5 and 6.

Returning to fig. 1, a blocking pin 25 is provided in an opening in the core 20. The blocking pin is spring biased downwardly by means of a spring 26 acting on an essentially disc-shaped portion 25a of the blocking pin.

The spring 26 is kept in position by a cover plate 27.

The blocking pin 25 is moveable between a first posi- tion, wherein it blocks the radial movement of a further or inner side bar 28, and a second position, wherein the radial movement of the inner side bar is not blocked.

The inner side bar functions to prevent mutual rota- tional movement of the core 20 and an adapter 30, as will be described in detail below with reference to figs. l0a-c.

The adapter 30 is substantially circular with an outer surface 30a with diameter corresponding to that of the main portion of the core 20. The adapter 30 has an aper- ture with a substantially circular inner surface 30b with a longitudinal groove 30c arranged to receive the inner side bar 28 of the core. There is also a concen- tric flange 30d covering about 90 degrees of the inner circumference of the adapter, see fig. 6.

The adapter ends in a tailpiece 30e arranged to be operatively connected to a stop washer 31, a bolt 32, a lock washer 33, and a nut 34. The bolt 32 is kept in place on the tailpiece by means of the nut 34 and thus rotates with the adapter, thereby being operatively con- nected to the locking mechanism of the lock. The adapter

is thus rotatably arranged in the inner portion of the cavity 10a, inside of the core 20.

In figs. 2 and 3 there is shown how the removable core 20 with an inserted key 21 is positioned in relation to the cylinder housing 10 during insertion or retraction of the core. From fig. 3 there is seen that the longitu- dinal groove 10b of the housing 10 is aligned with the longitudinal groove 30c of the adapter 30. This is to allow the outer side bar 22a to engage the groove 10b in the housing while the inner side bar 28 engages the groove 30c in the adapter.

In fig. 4 the assembled lock device is shown.

In fig. 5 the semi-circular extension 20c of the core 20 is shown with the groove 20d formed therein. The groove 20d is arranged to co-operate with the flange 30d of the adapter 30, which covers approximately 90 degrees of the inner surface of the adapter. When the core 20 is in- serted into the housing and the extension thereof en- gages the adapter 30, the core has a rotational position so that the extension 20c avoids the flange 30d. Sub- sequently, when the core is turned about 90 degrees in the housing, the flange 30d engages the groove 20d in the extension so as to provide a bayonet joint between the core and the adapter, thereby blocking longitudinal or axial movement of the core. Withdrawal of the core from the housing is thereby prevented. In that rota- tional position, the side bars 22,28 are aligned with a respective longitudinal groove 10b, 30c in the housing and the adapter, respectively, and engage therein.

The rotational blocking of the adapter relatively to the core will now be explained in detail, mainly with refer- ence to fig. 7, which is a top-sectional view of the lock device. It is there seen how the outer side bars 22a, 22b are pushed into engagement with the respective groove in the housing. When the key 21 is withdrawn, the outer side bars 22a, 22b are blocked from moving ra- dially inwardly and leaving the grooves in the housing due to the pin tumblers 29, thereby preventing rotation of the core in the housing when the key is removed, as is conventional. For a complete description of the operation thereof, see the above referenced publication.

The inner side bar 28, being pushed into engagement with the groove in the adapter, prevents mutual rotation of the core 20 and the adapter 30. The co-operation of the groove 20d in the core extension and the flange 30d pre- vents longitudinal movement of the core, thereby keeping it completely fixed in the housing.

The movement of the inner side bar 28 is controlled in a different way, as will be explained in detail below with reference to figs. l0a-c and lla-c. However, the differ- ence between a user key, shown in fig. 8, and a service key, shown in fig. 9, will first be explained.

In fig. 8 there is shown a user key 21'with a groove 21a arranged in a side surface of a key bit portion 21c and controlling the movement of the pin tumblers 29, as is conventional. The service key 21 shown in fig. 9 differs from the user key only in that there is provided a notch or indent 21b in the upper end portion of the key bit having an essentially planar surface. The notch

can have different heights or codes, denoted by the dis- tance"d"in the figure, which is the height from the bottom of the key bit to the planar surface of the notch. In a preferred embodiment,"d"can take three different values, thus providing three different service key codes.

With no key in the cylinder 20, the blocking pin 25 is pushed downwardly by the spring 26, see fig. 1, to a lower end position. In fig. 10a, which is a sectional view of the lock device with an inserted user key 21', there is seen how the upper forward slanting portion of the key has pushed the blocking pin 25 upwardly to a de- fined level. This is also shown in fig. 10b, which is an end view taken along the line lOb-lOb of fig. 10a and showing only the key 21', the blocking pin 25, the inner side bar 28, and the outer side bar 22b. It is here seen that the key acts on the essentially disc-shaped portion of the blocking pin, see also fig. 10c. In this posi- tion, a groove 25b in the blocking pin 25 is at a dif- ferent level than the inner side bar 28. The inner side bar is thus prevented from moving inwardly by the block- ing pin, as is indicated by the crossed-over arrow in fig. 10c. However, because the user key has correct code in the form of the side groove 21a, see fig 8, the outer side bars 22a, 22b are allowed to move inwardly, as indicated by the other arrow in fig. 10c. When the user key is turned, the core following the turning of the key can rotate relatively to the housing. Due to the inner side bar 28, the core 20 and the adapter 30 are not allowed to rotate relatively to each other. In other words, when the user key is turned, the adapter rotates with the core, bringing the bolt 32 attached to the

tailpiece 30e with it. All the time, the bayonet joint provided by the core extension 20c and the flange 30d prevents withdrawal of the core from the housing.

In fig. lla there is shown how a service key 21 having an indent 21b has pushed the blocking pin 28 to a dif- ferent level than the user key in fig. 10a. In fig. llb there is seen how the inner side bar 28 engages the groove in the blocking pin 25. The inner side bar 28 is thereby allowed to move inwardly from engagement with the longitudinal groove 30c in the adapter 30.

When the core 20 has been turned or rotated approxi- mately 90 degrees, the flange 30d of the adapter dis- engages from the groove 20d in the core, whereby the core is free to be withdrawn from the housing cavity 10a. A key operated removable core is thus provided.

In the figures there is also seen that part of the outer side bar 22a blocks inward movement of the inner side bar 28 when the outer side bar is engaging the groove in the core. This means that a service key 21 pushing the blocking pin 25 to a correct level for allowing the inner side bar to enter the groove in the blocking pin but having the wrong side code 21a will block inward movement of the outer side bar 22a, which in turn blocks inward movement of the inner side bar 28. In order to remove the core 20 from the lock a service key is re- quired which is provided with both correct code for the outer side bar and correct service key code for the in- ner side bar.

Several advantages are obtained with the described lock device. Firstly, a simple yet reliable solution is pro-

vided. Because a side bar or the like is used as means for bringing the adapter to rotate, a robust connection between core and adapter is obtained. Secondly,. because the same adapter can be used for locks adapted for both left-handed and right-handed doors, the number of dif- ferent parts needed is decreased. You only have to change the position of the stop washer 31.

A preferred embodiment of a lock device according to the invention has been described. A person skilled in the art realizes that this could be varied within the scope of the appended claims. Thus, although a lock having two outer side bars have been shown, the inventive idea is also applicable to locks having only one outer side bar or no side bars at all for the locking of the cylinder in the cylinder housing. Instead, a lock having conven- tional pin tumblers comprising top and bottom pins can be used with the invention.

An inner side bar has been described as the engagement element engaging an engagement element in the form of a groove in the adapter. However, the engagement elements can take may different shapes.