The invention relates to a cylinder lock, which can be implemented in the field of light industry, especially in the field of the locking devices for residential houses, public buildings etc.

Cylinder lock is known from BG No. 62182, consisting of a housing with an inner and an outer cylinder core fixed by rings thereto, as in the housing and in the inner core, which is longer than the outer core, there are formed coaxial bores wherein springs, housing and core pins are placed and on the outer part of the housing and on one of the cores there are stuffed additional steel inserts, and on the inner core there is mounted a cam fixed by a spring and a pin, as in the front part of the housing there is formed a slot providing a weaken cross section which guarantee that in case of a burglary attack the cylinder lock will break in the intended place, thereby the access to the opening of the lock and its unlocking is impossible as this opening rests filled with the housing of the cylinder lock which continues to operate with its original key even after the burglary attack. Said cylinder lock has a disadvantage - the cam whereby the locking and unlocking are realized is fixed on the inner core and the relevant locking and unlocking is possible only through the inner core by using two different keys - a short key to lock and unlock inside and a long key to lock and unlock outside. This is uncomfortable not only for the customer, but it limits the cylinder lock application. Only double-side cylinder lock could be performed, besides with limited length of the housing.

An other lock is known from DE 298 08 432 U1, this document discloses a cylinder lock comprising a housing, a cam and an inner core with a channel for a key and coaxial basic bores, wherein closing pins, springs, housing pins and core pins are placed, furthermore on the core an additional slot providing a weakened cross section is arranged and in the core inserts of hardened material are placed.

The present invention seeks to provide an improved construction of a cylinder lock having an increased protection against burglary as the locking and unlocking operations inside and outside are realized with the same key with keeping the number of the locking combinations.
There is thus provided a cylinder lock, consisting of a housing, a cam, in the front part of the housing there is a slot, as an inner and an outer cylinder core are fixed by rings thereto, said cores have a key channel for the key insertion, as in the housing and in the inner core coaxial basic bores are formed wherein closing pins, springs, housing and core pins are placed. In the outer part of the housing and in the front part of the outer core there are stuffed inserts of a hardened metal which have a protection function against drilling.
In accordance with the invention the cam is freely mounted between the inner and the outer core which both have identical lengths. Also, in the outer core there are formed basic bores which are coaxial with relevant basic bores formed in the housing, wherein closing pins, springs, housing and core pins are placed.
Throughout one of the basic bores of the outer core there is formed an additional slot arranged in the same plane with the slot formed in the housing, so that one common slot forms providing a weaken cross section wherein a plastic holder is mounted closing the common slot, so that therein a spring, a housing and a core pin are placed purposely to keep the number of locking combinations. With so formed common slot there is realized an anti-breaking protection of the cylinder lock. In the additional slot of the outer core there is formed a radial bore wherein a steel ball is placed to stabilize the outer core rotation, as the diameter of the ball is bigger than the width of the additional slot.
Besides, in accordance with the invention an anti-drilling protection is also realized in case of overcoming the anti-breaking protection, as next to the slot formed in the housing and next to the additional slot formed in the outer core there are mounted additional inserts of a hardened metal in relevant coaxial formed bores in the housing and in the outer core, which are chess-disposed to the basic housing and to the basic core bores. In accordance with the invention as well, in planes perpendicular to the plane of the key channel in the outer and in the inner core there are formed additional core bores wherein additional core pins are disposed, and inside the housing there are formed longitudinal channels with a configuration corresponding to the additional core pins configuration.
According to the invention a variant is given, where the cylinder lock consists of a housing, a cam, in the front part of the housing there is a slot, as an inner and an outer cylinder core are fixed by rings thereto, said cores have a key channel for the key insertion. The outer and the inner core have different lengths. In the housing and in the inner core there are formed coaxial basic bores wherein closing pins, springs, housing and core pins are disposed. In the outer part of the housing and in the front part of the outer core there are stuffed inserts of a hardened metal. In accordance with the invention the cam is freely mounted between the outer and the inner cores. In the back part of the housing there is formed a second slot, as in the outer core there are also formed basic bores which are coaxial with relevant basic bores formed in the housing , wherein closing pins, springs, housing and core pins are placed. Throughout one of the basic bores of the outer core and respectively of the inner core there are formed additional slots arranged in the same plane respectively with the slot formed in the front part of the housing and with the second slot formed in the back part of the housing, so that two common slots form respectively in the front and in the back part of the housing providing a weaken cross section wherein plastic holders are mounted closing the common slots so therein springs, housing and core pins are disposed. In the additional slots of the outer and of the inner core there are formed radial bores, in each of them there is mounted a steel ball, with a diameter bigger than the width of the additional slots. Next to the slot formed in the front part of the housing and next to the second slot formed in the back part of the housing as well as next to the additional slots formed in the outer and in the inner core there are mounted additional inserts of a hardened metal in respectively coaxial formed bores in the housing and in the outer and in the inner core which are chess-disposed to the basic housing bores and to the basic core bores. Besides, in planes perpendicular to the plane of the key channel in the outer and in the inner core there are formed additional bores wherein respectively additional core pins are disposed, and inside the housing there are formed longitudinal channels with a configuration corresponding to the additional core pins configuration.
The advantage of the cylinder lock in accordance with the invention consists in that with the improved anti-burglary function and with the kept number of the locking combinations the process of locking and unlocking outside and inside realizes by using the same key, both outside and inside the cylinder lock respectively through the outer and the inner core which are independent each other. This gives an opportunity for the product unification as the constructional limitation of the housing length dies out which allows a variation in the lengths of the outer and of the inner core and increases the cylinder lock application.
The cylinder lock in accordance with the invention can be implemented in each necessary configuration without size limitation like double, half or knob cylinder and in the master key systems or as a cylinder lock with special function as well.

The present invention will be understood and appreciated more fully from the following enclosed drawings:

• Fig. 1 represents an axonometric illustration of a symmetrical cylinder lock (with identical lengths of the inner and the outer core).
• Fig. 2 represents a cross-section of a symmetrical cylinder lock.
• Fig. 3 represents a view underneath of a symmetrical cylinder lock.
• Fig. 4 and fig. 5 represent sections in typical cuts of a symmetrical cylinder lock.
• Fig. 6 represents an axonometric illustration of an asymmetrical cylinder lock (with different lengths of the inner and the outer core).
• Fig. 7 represents a cross-section of an asymmetrical cylinder lock.
• Fig. 8 represents a view underneath of an asymmetrical cylinder lock.

One embodiment of the cylinder lock is shown in fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, whereat the cylinder lock comprises a housing 1, a cam 8, there is a slot 2 in the front part of the housing 1, as an inner 5 and an outer 4 cylinder core are fixed by rings 3 thereto, which have a channel 6 for a key 7 insertion, as in the housing 1 and in the inner core 5 there are formed coaxial basic bores 11 and 12 wherein closing pins 16, springs 13, housing pins 14 and core pins 15 are placed, as in the outer part of the housing 1 and in the front part of outer core 4 there are stuffed inserts 18 and 17 of a hardened metal, which have a protection function against drilling. The cam 8 is freely mounted between the outer 4 and the inner 5 core, which both have identical lengths, as in the outer core 4 there are also formed basic bores 12 which are coaxial with relevant basic bores 11 formed in the housing 1, wherein closing pins 16, springs 13, housing pins 14 and core pins 15 are placed. Throughout one of the said basic bores 12 of the outer core 4 there is formed an additional slot 9 arranged in the same plane with the slot 2 formed in the housing 1, so that one common slot forms providing a weaken cross section wherein a plastic holder 10 is mounted, closing the common slot, so that therein a spring 13, a housing pin 14 and a core pin 15 are placed purposely to keep the number of the locking combinations. In the additional slot 9 of the outer core 4 there is formed a radial bore wherein a steel ball 19 is mounted with a diameter bigger than the width of the additional slot 9. The said steel ball 19 is intended to stabilize the outer core 4 rotation. Next to the slot 2 and next to the additional slot 9 formed respectively in the housing 1 and in the outer core 4 there are mounted additional inserts of a hardened metal 21 and 20 in relevant coaxial formed bores 23 and 22 in the housing 1 and in the outer core 4 which are chess-disposed to the basic housing bores 11 and to the basic core bores 12. The said additional inserts 21 and 20 are intended to operate as an anti-drilling protection in case of overcoming the anti-breaking protection realized by the slot 2 and the additional slot 9. In planes perpendicular to the plane of the key channel 6 in the outer core 4 and in the inner core 5 there are formed additional bores 26 wherein additional core pins 24 are disposed and inside the housing 1 there are formed longitudinal channels 25 with a configuration corresponding to the additional core pins 24 configuration.

Another embodiment of the cylinder lock is shown in fig. 6, fig. 7 and fig. 8, whereat the cylinder lock consists of a housing 1', a cam 8, there is a slot 2 in the front part of the housing 1', as an outer 4' and an inner 5' cylinder core are fixed by rings 3 thereto, which have a channel 6 for a key 7 insertion. The outer 4' and the inner 5' cores have different lengths. In the housing 1' and in the inner core 5' coaxial basic bores 11 and 12 are formed wherein closing pins 16, springs 13, housing pins 14 and core pins 15 are placed, as in the outer part of the housing 1' and in the front part of the outer core 4' there are stuffed inserts 18 and 17 of a hardened metal. The cam 8 is freely mounted between the outer 4' and the inner 5' core. In the back part of the housing 1' there is formed a second slot 2', as in the outer core 4' there are formed also basic bores 12 which are coaxial with relevant basic bores 11 formed in the housing 1' wherein closing pins 16, springs 13, housing pins 14 and core pins 15 are disposed. Throughout one of the said basic bores 12 of the outer core 4' and respectively of the inner core 5' there are formed additional slots 9 and 9' arranged in the same plane respectively with the slot 2 and with the second slot 2' formed in the front and in the back part of the housing 1' so that two common slots form respectively in the front and in the back part of the housing 1' providing a weaken cross section wherein plastic holders 10 are mounted closing the common slots so that wherein springs 13, housing pins 14 and core pins 15 are placed. In the additional slots 9 and 9' of the outer 4' and of the inner core 5' there are formed radial bores, in each of them there is mounted a steel ball 19, with a diameter bigger than the width of the additional slots 9 and 9'. Next to the slot 2 and next to the second slot 2' formed in the housing 1' and next to the additional slots 9 and 9' formed respectively in the outer core 4' and in the inner core 5', there are mounted additional inserts of a hardened metal 21 and 20 in relevant coaxial formed bores 23 and 22 in the housing 1' and in the outer core 4' and in the inner core 5' which are chess-disposed to the basic housing bores 11 and to the basic core bores 12. Moreover, in planes perpendicular to the plane of the key channel 6 in the outer core 4' and in the inner core 5' there are formed additional bores 26 wherein respectively additional core pins 24 are disposed and inside the housing 1' there are formed longitudinal channels 25 with a configuration corresponding to the additional core pins 24 configuration. In this embodiment the execution of slots on both cylinder lock sides is necessary, because the assembly way of the cylinder lock is not known beforehand, and to guarantee its anti-burglary function it is necessary the formed common slot to be executed outside the lock during its assembly.

In accordance with the invention the cylinder lock using the associated key, operates as follows. When lock or unlock the cylinder lock outside or inside, the associated key 7 according to fig. 1, 2, 3, 4 and 5 inserts into the key channel 6 of the outer core 4 or of the inner core 5, whereat the core pins 15 and the additional core pins 24, being engaged in the relevant code combination on the key 7, fall respectively in the outer core 4 or in the inner core 5 and make possible their rotation in locking or unlocking direction. However, if the code combination on the key 7 is inaccurate, when the key 7 inserts into the key channel 6 of the outer 4 or of the inner 5 core, the core pins 15 don't fall in the respective core, and/or the additional core pins 24 block in the longitudinal channels 25 in the housing, which makes the rotation of the relevant core impossible, respectively the locking/ unlocking operations are also impossible.