WO1996002721A1

WO1996002721A1 - Electromechanically operated cylinder-key unit for locks

Info

Publication number: WO1996002721A1
Application number: PCT/EP1995/002758
Authority: WO
Inventors: Ezio Chies; Luciano Dassi; Vanni Gallocchio; Renato Botteon
Original assignee: Silca S.P.A.
Priority date: 1994-07-15
Filing date: 1995-07-14
Publication date: 1996-02-01
Also published as: IT1268670B1; EP0771381B1; EP0771381A1; ITVE940032A0; DE69513529T2; ATE186963T1; DE69513529D1; AU3110895A; ITVE940032A1

Abstract

An electromechanically operated cylinder-key unit for locks characterised by comprising in combination: a cylinder (2, 102) with a pawl (6, 106) rotatable mechanically by a key (4, 104), a key (4, 104) provided with its own identification code and control logic (46, 146), electrical-contactless coupling means (40, 48, 140, 148) between said key (4, 104) when inserted into the cylinder (2, 102) and the cylinder itself, a permanent magnet (18, 118) housed within said cylinder and rotatable by the key (4, 104), a magnetic circuit associated with said permanent magnet (18, 118), a winding (22, 122) housed in the cylinder (2, 102) and linked with said magnetic circuit, means (12, 64) for achieving mechanical coupling between the key (4, 104) and the pawl (6, 106), control logic (26, 126) housed in the cylinder (2, 102) and provided with an identification code for said cylinder, and interacting via said electrical-contactless coupling means (40, 48) with the control logic (46, 146) of the key (4, 104) when inserted into the cylinder, an electromechanical member (30, 31, 130, 131, 76, 78) for carrying out the mechanical rotational connection between the key (4, 104) and the pawl (6, 106) on recognizing correspondence between said key and said cylinder.

Description

Electromechanically operated cylinder-key unit for locks

This invention relates to an electromechanically operated cylinder-key unit for locks.

Mechanically operated cylinder-key units for locks are known. The cylinder comprises a plug rotating within a corresponding seat formed in the cylinder and is provided with a plurality of radial recesses which extend into an appendix provided in the cylinder body and housing axially movable pins formed from two parts. The axial position of each pin in its respective recess is determined by the depth of notches provided in the key inserted into the plug, and when this position is such as to cause the separation surface between the two parts of each pin to correspond with the cylindrical separation surface between the plug and its seat, the plug can be rotated by the key inserted into it and operate the lock to which the cylinder is applied.

This type of mechanically operated unit is widely used, but also has a series of drawbacks such as:

- a limited degree of security because of the substantially limited number of possible key patterns;

- a possibility of recognizing the key pattern "on sight";

- key wear both with use and with duplication;

- cylinder sensitivity to atmospheric conditions. To increase the degree of security of these known units it has been sought to make the key-cylinder interfacing mechanism increasingly more complicated so as to increase the number of possibile obtainable patterns, but this increase in pattern number is offset by a lower reliability and strength of the unit.

For this reason, lock operating systems have been proposed using electrical or electronic circuits able to electronically control a code memorized- in that part of the unit which operates the lock with a code resident in the key.

The need to use electrical power is a considerable inconvenience: if the electricity derives from the mains, the system can be used only if a mains supply is present and becomes unusable if the supply fails; if however the electricity derives from a self-contained source, the state of its charge must be systematically checked.

To avoid this inconvenience it has been proposed to provide mixed units, ie mechanically operated but with an electronic control system powered by electricity generated on inserting the key into the lock cylinder or on rotating the key already inserted in it.

FR-A-2 500 520 describes a unit of this type in which the electricity necessary for effecting the key-cylinder recognition and for powering the electromechanical bolt release member on positive recognition is generated by a piezoelectric effect by virtue of the action exerted on piezocrystals when the key is inserted, withdrawn or rotated, these being arranged along the lock channel.

A drawback of this arrangement is the very small amount of electricity produced, this generally being insufficient to satisfy the required electrical loads, which are themselves modest; a further drawback is the high electrical voltage produced, and generally incompatible with that required for the particular type of electrical loads concerned; a further drawback is the nature of the memorized code resident in the key and the method of trasmitting the relative data to the reading, recognition and enabling circuits resident in the lock mechanism. In this respect, if this code is of mechanical type and operates by pressure against appropriate feelers in the lock, it is easily decoded on sight; if it is of magnetic type for reading by suitable magnetic readers it can be easily cancelled or altered; if it is of optical type it is very complicated and requires considerable energy for its operation.

US-A-5 265 452 describes a unit comprising a cylinder into which a key comprising a memorized code can be inserted and rotated. The rotation of the inserted key generates sufficient electricity to enable the lock to recognize the key code and, on positive recognition, to effect engagement between gearwheels enabling the lock bolt to be operated by the key.

This solution, which inter alia is described in terms of general principles without any mention of the manner of energizing the electronic code provided in the key, or the reading and control arrangements provided external to the key, has the drawback of considerable constructional complexity and the practical impossibility of totally housing it within a cylinder of the type interchangeable with traditional European lock cylinders, hence allowing it to be applied only to locks expressly constructed for this purpose. An object of the invention is to eliminate the drawbacks jointly or separately encountered in known cylinder-key units for locks by providing an electromechanically operated unit wityh self-generated electrical power, the key also being without contained power and provided with a memorized identifying code which is not detectable at sight, and comprising control logic and a locking mechanism which are entirely contained within the overall limits of the cylinder, which is therefore interchangeable with traditional cylinders of European type.

This object and further ones are attained according to the invention through an electromechanically operated cylinder-key unit for locks is described in claim 1. Preferred embodiments of the present invention are described in detail hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal section through the cylinder of a first embodiment of the unit according to the invention, shown without the key and in the deactivated state; Figure 2 shows the same view as Figure 1 but with the key inserted and in the activated state; Figure 3 shows a second embodiment in the same view as Figure 1, without the key and in the deactivated state; Figure 4 shows it in the same view as Figure 1 but with the key inserted and in the activated state, Figure 5 shows a third embodiment of the cylinder in the same view as Figure 1, shown without the key and in the deactivated state, Figure 6 shows the same view as Figure 5 but with the key inserted and in the activated state, Figure 7 shows it according to the cross section VII-VII of

Figure 5, Figure 8 shows the same view as Figure 7 in the phase immediately subsequent to the insertion of the key, Figure 9 shows it according to the cross section IX-IX of

Figure 6, and Figure 10 shows in the same view as Figure 8 during the phase of operating the key. As can be seen from the figures, in the embodiment shown in Figures 1 and 2, the unit according to the invention comprises a cylinder indicated overall by 2, and a key indicated overall by 4.

The cylinder 2 comprises a cylindrical portion containing the members which enable the key 4 to be inserted, and an appendix extending radially from said cylindrical portion and housing the components allowing interaction between the cylinder and the key inserted into it. The unit is of standard shape and dimensions, corresponding to currently used standards, so that traditional cylinders provided with a plug and pins can be replaced by the cylinder according to the invention. With the cylindrical portion of the cylinder 2 there is also associated a pawl member 6 comprising a cylindrical part able to rotate about the axis of the key 4 and an actual pawl projecting from the outer surface of said cylindrical portion to activate a traditional bolt (not shown) with which the lock is provided.

Within the cylindrical portion of the cylinder 2 in a position facing a circular aperture 8 provided in the corresponding front wall 10 there is housed an engagement member 12 which is free to move axially and rotationally within its seat. It is opposed in its axial movements by a spring 14 resting on an annular step provided in a ring 16 coaxial with the cylindrical cavity of the cylinder 2. The ring 16 is frontally toothed and engages a corresponding toothed portion provided in a permanent magnet 18 of cylindrical shape housed in the radial appendix of the cylinder 2 and having its axis perpendicular to the axis of the ring 16.

With the permanent magnet 18 there is associated a magnetic circuit 20 linked with a winding 22, the terminals of which are connected across a rectifier (not shown) which is connected to a capacitor 24, also housed in the radial appendix of the cylinder 2. This appendix also houses a microprocessor 26 which controls the operation of the system, as described hereinafter.

The engagement member 12 comprises a circumferential rib 27 which on that side facing the cylinder aperture 8 rests on a corresponding annular flange 28 of the ring 16 to hence oppose the reaction of the spring 14, and on the opposite side opposes the movable core 30 of an electromagnet 31 housed in the radial cavity of the cylinder 2. The core 30 is movable axially between a position in which it interferes with the axial movements of said engagement member 12 and a position of non-interference.

That end of engagement member 12 facing the aperture 8 of the cylinder 2 comprises a diametrical notch 32 engageable by a corresponding diametrical appendix 34 provided on the key 4, the opposite end of the engagement member 12 comprising a diametrical appendix 36 arranged to engage in a corresponding notch 38 provided in the pawl 6. That portion of the cylindrical cavity of the cylinder 2 which is adjacent to the aperture 8 comprises a winding 40 acting as an annular antenna for the cylinder.

The key 4 comprises an operating head 42 and a cylindrical shank 44 on which a microprocessor 46 and a winding 48 are mounted.

This latter forms for the key 4 an annular antenna which faces the antenna 40 when the key is inserted into the cylinder 2 and has its appendix 34 engaged in the diametrical notch 32 in the engagement member 12.

The cylinder microprocessor 26 and the key microprocessor 46 are arranged for the mutual dialogue, both comprising a memory containing inter alia the identifying code for the cylinder and key, and all the other components described in the description of operation of unit according to the invention.

To better understand this operation, reference will be made to the situation in which the key 4, containing its identifying code in the microprocessor 46, is separated from the cylinder 2 (see Figure 1) , which contains its own identifying code in the microprocessor 26. In this situation the spring 14 maintains the engagement member 12 with its circumferential rib 27 resting on the annular flange 28 of the ring 16 and hence with its appendix 36 disengaged from the notch 38 provided in the pawl 6. A spring 50 associated with the core 30 of the electromagnet 31 maintains it in a position of intereference with the circumferential rib 27 of the engagement member 12 and practically prevents this from undergoing any axial movement. Consequently if when in this state the key 4 is inserted into the cylinder 2 so that its appendix 34 engages the notch 32 provided in said engagement member, this can be rotated by rotating the key but cannot yield axially.

To now operate the lock the key must be rotated through one or more revolutions. In this manner, as the engagement member 12 is rotationally rigid with the ring 16 and because of the engagement between the complementary toothed profiles, the rotation of the engagement member causes the toothed gear 16 to rotate together with the permanent magnet 18 associated with it.

The rotation of the permanent magnet 18 results in a variation in the flux through the magnetic circuit associated with it, this flux variation inducing in the winding 22 an electromotive force causing a current to circulate which charges the capacitor 24.

The electrical energy stored in the capacitor is used to power the cylinder microprocessor 26 via a cable and to power the key microprocessor 46 by induction by virtue of the coupling between the facing windings 40,48.

The hence powered microprocessor 26 feeds the identifying code for the cylinder 2 using the same coupling between the two facing windings 40, 48, this code when received by the microprocessor 46 being compared with the cylinder codes resident therein and identifying the cylinders with which the key 4 is required to interact. If this comparison is positive the microprocessor 46 feeds its ow key identification code to the microprocessor 26.

This key identification code is compared by th microprocessor 26 with the key codes resident within it an identifying the keys with which the cylinder 2 can interact, then if this comparison is also positive it causes the capacitor 24 to power the electromagnet 31.

The energizing of the hence powered electromagnet 31 causes its core 30 to retract from the position in which it interferes with the circumferential rib 27 of the engagement member 12, to enable this latter, under the thrust of the key 4, to engage the pawl 6 (see Figure 2) and operate it by rotating the key.

On termination of this operation the key 4 is extracted from the cylinder 2, the spring 14 then returning the engagement member 12 into its initial position and the spring 50 returning the core 30 of the electromagnet 31 into the position in which it interferes with said engagement member 12, to prevent its subsequent axial movement.

It is apparent that the cylinder-key unit of the invention has many advantages over traditional units, and in particular: - it requires no connection to the mains supply, neither does it require any powering battery;

- it uses keys which are apparently identical to each other and unable to reveal their code by direct observation;

- it offers a very high level of security because of the practically unlimited number of usable codes and the meticulous checking operations performed before enabling cylinder operation;

- externally it is in the form of a cylinder having the same shape and dimensions as those of traditional mechanical cylinders, which can be easily replaced by it.

In the embodiment shown in Figure 3 and 4 based on the aforedescribed general principle, the engagement member 12, which is operated by the key 4 and, following key recognition by the logic control circuit, can be thrust axially to engage the pawl 6, is contructed in a more advantageous manner. Specifically, said engagement member comprises an outer part 52 forming a sort of stopper for the cylinder aperture 8, and an inner part 54 provided with a circumferential rib 27. The two parts, between which a spring 14 is interposed, are telescopically movable relative to each other, but are mutually constrained in rotation.

With the outer part 52 of the engagement member 12 there is associated a stem 56, which is rigid with said outer part 52 in terms of axial movement but can slide axially relative to the inner part 54. Said stem 56 has a pointed end 36 which together with a facing point 39 projecting from the cylindrical cavity of the pawl 6 forms the guide for a spring 58.

The outer surface of the inner part 54 of the engagement member 12 comprises parellel ribs to be inserted into corresponding parallel grooves provided in the cylinder cavity of the pawl 6 to engage it for rotation. The operation of this second embodiment of the unit according to the invention is identical to the preceding with regard to the electrical and electronic part, but is different with regard to the mechanical part.

In particular, when the key 4 is not inserted into the cylinder 2 (see Figure 3) , the outer part 52 of the engagement member 12 closes the cylinder aperture 8 and protects the winding 40 adjacent to said aperture 8 from the external environment. On inserting the key, the outer part 52 of the engagement member 12 yields axially inwards to compress the spring 14, as the inner part 54 is prevented by the core 30 of the electromagnet 31 from undergoing axial movement. At the same time the axial movement of the outer part 52 of the engagement member 12 loads the spring 14 and axially thrust the stem 56 to load the spring 58.

After the key 4 has been recognized by the cylinder 2 and the electromagnet 31 has been activated, engagement with the pawl 6 is not achieved by further axial pushing of the key as in the preceding case, but instead by the effect of the spring 14 which urges the inner part 54 of the engagement member 12 so that its ribs engage the grooves of the pawl 6 (see Figure 4) .

In this manner, in addition to the previously achieved advantages, there is the further advantage of making the load on the core 30 of the electromagnet 31 independent of the force with which the key is pushed axially, this also preventing damaging forcing of the lock. In this respect, to prevent possible tampering of the lock, the annular seat provided in the cylinder body for the larger-diameter portion of the ring 16 has a slight taper 60 in its lateral wall and toothing 62 on its rear wall, in this manner if an axial blow is applied for tampering purposes to the outer portion 52 of the engagement member 12 to cause the core 30 of the electromagnet 31 to yield, this blow is ineffective because:

- a portion of the pawl 6 opposes possible yielding of said core 30;

- any axial movement of the outer portion of the engagement member 12 results both in the toothed ring 16 being forced into the surrounding conical seat 60 and the toothed portion of said ring 16 becoming engaged in the toothing 62 present on the rear wall of the conical seat; - both these circumstances preventing rotation of said ring and the electrical energy generation which this rotation provides.

The embodiment shown in figures 5-10, without prejudice to the general principium above mentioned, with all the previous listed advantages, differs from the preceding substantially for the way of producing the electrical energy necessary for the recognizing and the release, as well as for the fact that, in absence of the key or in presence of a key not recognized, the pawl is kept blocked. As it may be seen in these figures, in the cylindrical cavity of the cylinder 102 a plug 64 is housed longitudinally provided with a seat 66 for the insertion of the key 104. This key, unlike the previous ones, presents a characteristic shape with the shank 144 flat and incorporating in the central zone an antenna 140 and a microprocessor 146. It further presents a shaped outline, visible in Figures 8-10 and on a side of a longitudinal groove presents a rack 68, with which a pinion 70 may engage, rotationally rigid with a magnet 118, housed in a suitable seat inside the plug 64. To this magnet 118 a winding 122 is associated which, through a pair of wiping contacts 72,72', is connected to a capacitor 124.

To the same capacitor 124 are further connected, always through the wiping contacts 72,72', a microprocessor 126 and an antenna 148; to the microprocessor 126 is in its turn connected the winding of an electromagnet 131 provided with core 130.

The plug 64 and the remaining part of the cylinder 102 are provided with a cylindrical cavity 74, transverse to the axis of the same plug and provided partly in one and partly in the other. Within this seat 64 a hollow pin is housed which may axially slide, the pin being formed from two elements 76 and 78, separate each from other by a discontinuity surface which for a well definite axial position of said pin (release position) extends the cylindrical discontinuity surface between the plug 64 and its seat in the cylinder 102. An end of the element 76 of the pin is point-shaped and, urged by a spring 80 acting on the other element 78, invades the seat 66 foreseen in the plug 64 for the key 104. To this other element 78 a contrasting element 82 is applied made in ferromagnetic material and having the point projecting into the inside of the axial cavity limited by said elements 76 and 78. The head of the core 130 of the electromagnet 131 is housed in this cavity, and an orientated permanent magnet 84 is housed between said head and the contrasting element 82.

The operation of the cylinder-key unit according to this third embodiment is the following: when the key is not inserted (see Figures 5 and 7) the spring 80 keeps the pin 76,78 with the end of the element 76 housed within the longitudinal seat 66 of the plug 64 for the key 104. In this configuration the separation surface between the two elements 76 and 78 as well as between the head of the core 130 and the permanent magnet 84 is distinct from the discontinuity surface between the plug 64 and the cylinder 102 and therefore the same plug and, with this the pawl 106, are blocked in rotation.

The insertion of the key 104 into the seat 66 causes, thank to the engagement of its rack 68 with the pinion 70, the rotation of the magnet 118 and the induction in the winding 122 of a current which, through the wiping contacts 72,72', charges the capacitor 124.

When the key is completely inserted into its seat 66, its antenna 140 faces the antenna 148 provided in the plug 64 and this allows that the respective control logics 146 a 126 carry out the mutual recognition between key a cylinder. At the same time the insertion of the key 104 in the seat 66 causes the axial displacement of the pin 76, along the cavity 74 against the elastic reaction of t spring 80, until the separation surface between elements and 78 coincides with the discontinuity surface between t plug 64 and its seat in the cylinder 102. In th configuration (see fig. 8) the plug 64 and the pawl 106 a again blocked in rotation, since the permanent magnet 84 adherent to the core 130 of the electromagnet 131 and the contact surface doesn't coincide with the discontinui surface between the plug 64 and cylinder 102.

In the case the recognition occurs between te key 1 and the cylinder 102, the delivery of a current pulse caused from the capacitor 124 to the electromagnet 131, whi magnetises for a short time the core 130 so as to cause t repulsion of the permanent magnet 84 and to make it to adhe to the contrasting element 82 (see fig. 9) . This causes t release of the plug 64 which may be activated in rotati through the same key 104 and in this way may rotate the pa 106. It has to be pointed out that during this phase, t contrasting element 82, made of ferromagnetic materia magnetizes itself for induction at the contact with the permanent magnet 84 and keeps it adhering to it even in the case of cessation of the repulsive effect from the electromagnet 130. At the end of the operating of the lock, that is when the key 104 is brought into its initial position and subsequently is extracted from its seat 66, the elastic reaction of spring 80, no more urged, brings the pin 76,78 in the configuration of locking of the plug 64, that is in the configuration in which both the element 78 and the permanent magnet 84 impede the rotation of the same plug (see figures 5 and 7) . It has to be pointed out that the subsequent insertion of the key 104 and the corresponding axial displacement of the pin 76,78 will cause the detachment of the contrasting element 82 from the permanent magnet 84, which will adhere to the core 130 of the electromagnet 131 until the occured recognition between key and lock, since the contact surface core 130 - permanent magnet 84 is larger than the contact surface contrasting element 82 - permanent magnet 84.

From what above said it clearly results that this third embodiment of the unit according to the invention, together with the advantages of the previous embodiments, presents the further adavantages consisting in keeping locked the pawl 10 in absence of key or in presence of a not recognized key, a well as in the elimination of the need of rotating the ke inserted into the plug to generate the current necessary t the recognition and the release.

Claims

- 21 -

C L A I M S 1. An electromechanically operated cylinder-key unit for locks characterised by comprising in combination:

- a cylinder (2,102) with a pawl (6,106) rotatable mechanically by a key (4,104),

- a key (4,104) provided with its own identification code and control logic (46,146),

- electrical-contactless coupling means (40,48,140,148) between said key (4,104) when inserted into the cylinder (2,102) and the cylinder itself,

- a permanent magnet (18,118) housed within said cylinder and rotatable by the key (4,104),

- a magnetic circuit associated with said permanent magnet (18,118), - a winding (22,122) housed in the cylinder (2,102) and linked with said magnetic circuit,

- means (12,64) for achieving mechanical coupling between the key (4,104) and the pawl (6,106),

- control logic (26,126) housed in the cylinder (2,102) and provided with an identification code for said cylinder, and interacting via said electrical-contactless coupling means (40,48) with the control logic (46,146) of the key (4,104) when inserted into the cylinder, - an electromechanical member (30,31,130,131,76,78) f carrying out the mechanical rotational connection betwe the key (4,104) and the pawl (6,106) on recognizi correspondence between said key and said cylinder. 2. A unit as claimed in claim 1, characterised in that t key (4,104) is provided with an antenna (48,148) which, wh the key is inserted into the cylinder (2,102), is coupl with an antenna (40,140) provided in the cylindrical cavit of the cylinder, said antennas (40,48,140,148) bein electrically connected to the control logics (46,26,146,126 of the key and cylinder respectively.

3. A unit as claimed in claim 2, characterised in that th antenna (48,148) of the key (4,104) and the antenna (40,140 of the cylinder (2,102) consist of coaxial coils. 4. A unit as claimed in claim 1, characterised by comprisin a device (24,124) for storing the electrical energy generate in said winding (22,122), said device (24,124) bein electrically connected at least during the recognizing phase to the control logic (26,126) of the cylinder (2,102). 5. A unit as claimed in claim 4, characterised in that sai storage device (24,124) is a capacitor.

6. A unit as claimed in claim 4, characterised in that sai storage device is a rechargeable battery. 7. A unit as claimed in claim 1 characterised in that the coupling means (12) between key (4) and pawl (6) are of disengaging type.

8. A unit as claimed in claim 1, characterised in that the cylinder (2) houses an essentially cylindrical engagement member (12) which is free to rotate about its axis and is also able to move axially between a position in which it mechanically engages said pawl (6) and a position disengaged therefrom. 9. A unit as claimed in claim 8, characterised in that within the cylinder (2) there is provided an electromagnet (31) , the core (30) of which is positioned radially to said engagement member (12) and is movable between two axially distinct positions, namely of interference with and of non- interference with said engagement member respectively.

10. A unit as claimed in claim 9, characterised in. that the engagement member (12) comprises a circumferential rib (27) which interacts with the core (30) of said electromagnet (31) when this is in its interference position. ll. A unit as claimed in claim 10, characterised in that with the core (30) of the electromagnet (31) there is associated a spring (50) which when excitation is absent maintains it in the condition of interference with said circumferential rib (27) .

12. A unit as claimed in claim 8, characterised in that th engagement member (12) is provided at its outer end wit means (32) for its direct mechanical coupling to the key (4 when inserted into the cylinder (2) .

13. A unit as claimed in claims 10 and 12, characterised i that the engagement member (12) comprises:

- two parts (52,54) telescopically movable relative to eac other but mutually constrained in rotation, namely an oute part (52) provided with said means (32) for direc mechanical coupling to said key (4) and an inner part (54 provided with a perimetral rib (27) and with means (36) fo direct mechanical coupling to said pawl (6) when th electromagnet core is disengaged from the perimetral ri (27),

- a stem (56) axially movable under the control of said oute telescopic part (52) ,

- a first spring (14) interposed between said telescopi parts (52,54), and - a second spring (58) interposed between said stem (56) an said pawl (6) .

14. A unit as claimed in claims 10 and 12, characterised i that the engagement member (12) comprises: - two parts (52,54) telescopically movable relative to each other but mutually constrained in rotation, namely an outer part (52) provided with means (32) for direct mechanical coupling to said key (4) and an inner part (54) provided with a perimetral rib (27) ,

- a stem (56) axially traversing said engagement member (12) and having its outer end opposing said outer part (52) and its inner end opposing said inner part (54) ,

- a first spring (14) interposed between said telescopic portions (52,54) , and

- a second spring interposed between said stem (56) and said pawl (6) .

15. A unit as claimed in claim 13 and/or claim 14, characterised in that the outer surface of the inner part (54) of the engagement member (12) comprises parallel ribs cooperating with parallel grooves provided in a complementary seat formed in the pawl (6) for their mutual rotational coupling.

16. A unit as claimed in claim 8, characterised in that within the cylindrical cavity in said cylinder (2) there is housed a toothed ring (16) within which said engagement member (12) is axially movable but rotationally constrained, said ring (16) being mechanically coupled to said permanent magnet (18) , the axis of which is perpendicular to the ri axis.

17. A unit as claimed in claim 16, characterised in that t ring (16) is frontally toothed, the permanent magnet (18 having a toothed cylindrical portion engaged with the fro toothing of said ring.

18. A unit as claimed in claim 17, characterised in that t cavity provided in the cylinder (2) for the toothed ring (16 has a side wall with a slight taper (60) and a toothed en wall (62).

19. A unit as claimed in claim 1 characterised by comprisin a plug (64) associated to the pawl (106) and provided with longitudinal seat (66) for the key (104), with a seat for th permanent magnet (118) rotatably operated during th insertion of the key, and a moving member (76,78,84) for th controlled locking in rotation of said plug (64) with respec to said cylinder (102).

20. A unit as claimed in claim 19 characterised in that th permanent magnet (118) is associated to a pinion (70) partially projecting into the seat (66) of the plug (64) an cooperating with a rack (68) foreseen in the key (104) t cause the rotation of said magnet (118) when the key i inserted into the lock. 21. A unit as claimed in claim 19 characterised in that to the moving member (76,78,84) the core (130) of an electromagnet (131) is associated, which is suitable to bring in release condition said moving member, when the recognition has occurred of the key (104) inserted into its seat (66) of the plug (64) .

22. A unit as claimed in claim 19 characterised in that the member for rotationally locking the plug (64) comprises a pair of cylindrical hollow elements (76,78) mobile between a locking position, in which an element (78) interferes with the rotation of the plug (64) in its seat, and a release position, in which said element (78) is kept in non interference condition with the rotation of the plug (64) and comprises an orientated permanent magnet (84) independently movable within the axial cavity limited by said elements (76,78) between a locking position, in correspondence of which it adheres to a portion of the core (130) of the electromagnet (131) , and a release position, in correspondence of which it is taken away for repulsion from said electromagnet (131) in non interference condition with the rotation of the plug (64) .

23. A unit as claimed in claim 22 characterised by comprising a spring (80) acting so as to keep the pair of cylindrical hollow elements (76,78) in locking condition, with one (76) of said elements partially invading the sea (66) provided in the plug (64) for the key (104) . 24. A unit as claimed in claim 22 characterised in that t the element (78) of the pair of cylindrical element (76,78) is applied a contrasting element (82) , made of ferromagnetic material, the contact surface of which with the permanent magnet (84) is lesser than the contact surface with the core (130) of the electromagnet (131) .