[0001] This invention relates to an electromechanically operated cylinder-key unit for locks.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] EP 0 462 316, the document upon which the preamble of claim 1 is based relates to
a double lock cylinder having electric locking means which can be activated by means
of an electrical signal generated by the appropriate key, and proposes that a generator
supplying voltage during closing actuation be arranged in one cavity of the cylinder
core.
[0013] 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 with 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] The key 4 comprises an operating head 42 and a cylindrical shank 44 on which a microprocessor
46 and a winding 48 are mounted.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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 own key identification code to the microprocessor
26.
[0031] This key identification code is compared by the microprocessor 26 with the key codes
resident within it and 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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).
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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 74 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.
[0046] 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.
[0047] 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.
[0048] 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
and 126 carry out the mutual recognition between key and cylinder. At the same time
the insertion of the key 104 into the seat 66 causes the axial displacement of the
pin 76,78 along the cavity 74 against the elastic reaction of the spring 80, until
the separation surface between elements 76 and 78 coincides with the discontinuity
surface between the plug 64 and its seat in the cylinder 102. In this configuration
(see fig. 8) the plug 64 and the pawl 106 are again blocked in rotation, since the
permanent magnet 84 is adherent to the core 130 of the electromagnet 131 and their
contact surface doesn't coincide with the discontinuity surface between the plug 64
and cylinder 102.
[0049] In the case the recognition occurs between the key 104 and the cylinder 102, the
delivery of a current pulse is caused from the capacitor 124 to the electromagnet
131, which magnetises for a short time the core 130 so as to cause the repulsion of
the permanent magnet 84 and to make it to adhere to the contrasting element 82 (see
fig. 9). This causes the release of the plug 64 which may be activated in rotation
through the same key 104 and in this way may rotate the pawl 106. It has to be pointed
out that during this phase, the contrasting element 82, made of ferromagnetic material,
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.
[0050] 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.
[0051] 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 106 in absence of key
or in presence of a not recognized key, as well as in the elimination of the need
of rotating the key inserted into the plug to generate the current necessary to the
recognition and the release.
1. An electromechanically operated cylinder-key unit for locks 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 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 selectively achieving mechanical coupling between the key (4,104)
and the pawl (6,106),
- control logic (26,126) associated with the cylinder (2,102) and provided with an
identification code for said cylinder, and interacting via said electrical 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) which enables said means (12,64)
to selectively achieve the mechanical rotational connection between the key (4,104)
and the pawl under control of said control logic (6,106) on recognizing correspondence
between the identification codes of said key and said cylinder respectively, and
- a device (24,124) for storing the electrical energy generated in said winding (22,122),
said device (24,124) being electrically connected at least during the recognizing
phase, to the control logic (26,126) of the cylinder (2,102),
characterised in that:
- the electrical coupling means (40,48,140,148) between key and cylinder (2,102) are
electrical contactless coupling means; and
- the control logic (26,126) associated with the cylinder (2,102) is housed in the
cylinder so as to interact with the control logic (46,146) of the key via said contactless
electrical coupling means.
2. A unit as claimed in claim 1, characterised in that the key (4,104) is provided with
an antenna (48,148) which, when the key is inserted into the cylinder (2,102), is
coupled with an antenna (40,140) provided in the cylindrical cavity of the cylinder,
said antennas (40,48,140,148) being 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 the 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 in that said storage device (24,124) is
a capacitor.
5. A unit as claimed in claim 1, characterised in that said storage device is a rechargeable
battery.
6. A unit as claimed in claim 1 characterised in that the coupling means (12) between
key (4) and pawl (6) are of disengaging type.
7. 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.
8. A unit as claimed in claim 7, 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.
9. A unit as claimed in claim 8, 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.
10. A unit as claimed in claim 9, 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).
11. A unit as claimed in claim 7, characterised in that the engagement member (12) is
provided at its outer end with means (32) for its direct mechanical coupling to the
key (4) when inserted into the cylinder (2).
12. A unit as claimed in claims 9 and 11, characterised in 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 said means (32) for direct mechanical
coupling to said key (4) and an inner part (54) provided with a perimetral rib (27)
and with means (36) for direct mechanical coupling to said pawl (6) when the electromagnet
core is disengaged from the perimetral rib (27),
- a stem (56) axially movable under the control of said outer telescopic part (52),
- a first spring (14) interposed between said telescopic parts (52,54), and
- a second spring (58) interposed between said stem (56) and said pawl (6).
13. A unit as claimed in claims 9 and 11, characterised in 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).
14. A unit as claimed in claim 12 and/or claim 13, 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.
15. A unit as claimed in claim 7, 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 ring axis.
16. A unit as claimed in claim 15, characterised in that the ring (16) is frontally toothed,
the permanent magnet (18) having a toothed cylindrical portion engaged with the front
toothing of said ring.
17. A unit as claimed in claim 16, characterised in that the cavity provided in the cylinder
(2) for the toothed ring (16) has a side wall with a slight taper (60) and a toothed
end wall (62).
18. A unit as claimed in claim 1 characterised by comprising a plug (64) associated to
the pawl (106) and provided with a longitudinal seat (66) for the key (104), with
a seat for the permanent magnet (118) rotatably operated during the insertion of the
key, and a moving member (76,78,84) for the controlled locking in rotation of said
plug (64) with respect to said cylinder (102).
19. A unit as claimed in claim 18 characterised in that the permanent magnet (118) is
associated to a pinion (70), partially projecting into the seat (66) of the plug (64)
and cooperating with a rack (68) foreseen in the key (104) to cause the rotation of
said magnet (118) when the key is inserted into the lock.
20. A unit as claimed in claim 18 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).
21. A unit as claimed in claim 18 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).
22. A unit as claimed in claim 21 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 seat (66) provided in the plug (64)
for the key (104).
23. A unit as claimed in claim 21 characterised in that to 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).
1. Elektromechanisch betriebene Zylinder/Schlüssel-Einheit für Schlösser mit in Kombination:
- einem Zylinder (2), 102) mit einem Riegel (6, 106), der durch einen Schlüssel (4,
104) mechanisch drehbar ist,
- einem Schlüssel (4, 104), der mit seinem eigenen Identifizierungcode und seiner
eigenen Steuerlogik (46, 146) versehen ist,
- einer elektrischen Kopplungseinrichtung (40, 48, 140, 148) zwischen dem Schüssel
(4, 104), wenn dieser in den Zylinder (2, 102) eingeführt ist, und dem Zylinder selbst,
- einem Dauermagneten (18, 118), der in dem Zylinder aufgenommen ist und durch den
Schlüssel (4, 104) drehbar ist,
- einer Magnetschaltung, die mit dem Dauermagneten (18, 118) verbunden ist,
- einer Windung (22, 122), die in dem Zylinder (2, 102) aufgenommen ist und mit der
Magnetschaltung verbunden ist,
- Mitteln (12, 64) zum selektiven Erreichen einer mechanischen Kopplung zwischen dem
Schlüssel (4, 104) und dem Riegel (6, 106),
- einer Steuerlogik (26, 126), die mit dem Zylinder (2, 102) verbunden ist und mit
einem Identifizierungcode für den Zylinder versehen ist, und über die elektrische
Kopplungseinrichtung (40, 48) mit der Steuerlogik (46 146) des Schlüssels (4, 104)
zusammenwirkt, wenn dieser in den Zylinder eingeführt ist,
- einem elektromechanischen Teil (30, 31, 130, 131, 76, 78), welches das Mittel (12,
64) in die Lage versetzt, die mechanische Drehverbindung zwischen dem Schlüssel (4,
104) und dem Riegel (6, 106) unter Steuerung der Steuerlogik bei Erkennung einer Übereinstimmung
zwischen den Identifizierungscodes des Schlüssel bzw. des Zylinders selektiv zu erreichen,
und
- einer Einrichtung (24, 124) zum Speichern der in der Windung (22, 122) erzeugten
elektrischen Energie, wobei die Einrichtung (24, 124) wenigstens während der Erkennungsphase
mit der Steuerlogik (26, 126) des Zylinders (2, 102) elektrisch verbunden ist,
dadurch gekennzeichnet, daß
- die elektrische Kopplungseinrichtung (40, 48, 140, 148) zwischen Schlüssel und Zylinder
(2, 102) eine elektrisch berührungslose Kopplungseinrichtung ist; und
- die mit dem Zylinder (2, 102) verbundene Steuerlogik (26, 126) in dem Zylinder aufgenommen
ist, um so mit der Steuerlogik (46, 146) des Schlüssels über die berührungslose elektrische
Kopplungseinrichtung zusammenzuwirken.
2. Einheit nach Anspruch 1, dadurch gekennzeichnet, daß der Schlüssel (4, 104) mit einer
Antenne (48, 148) versehen ist, welche, wenn der Schlüssel in den Zylinder (2, 102)
eingeführt ist, mit einer Antenne (40, 140) gekoppelt ist, die in dem Zylinderhohlraum
des Zylinders vorgesehen ist, wobei die Antennen (40, 48, 140, 148) mit den Steuerlogiken
(46, 26, 146, 126) des Schlüssels bzw. des Zylinders elektrisch verbunden sind.
3. Einheit nach Anspruch 2, dadurch gekennzeichnet, daß die Antenne (48, 148) des Schlüssels
(4, 104) und die Antenne (40, 140) des Zylinders (2, 102) aus koaxialen Spulen bestehen.
4. Einheit nach Anspruch 1, dadurch gekennzeichnet, daß die Speichereinrichtung (24,
124) ein Kondensator ist.
5. Einheit nach Anspruch 1, dadurch gekennzeichnet, daß die Speichereinrichtung eine
wiederaufladbare Batterie ist.
6. Einheit nach Anspruch 1, dadurch gekennzeichnet, daß die Kopplungseinrichtung (12)
zwischen Schlüssel (4) und Riegel (6) von ablösender Art ist.
7. Einheit nach Anspruch 1, dadurch gekennzeichnet, daß der Zylinder (2) ein im wesentlichen
zylindrisches Eingreifelement (12) aufnimmt, welches um seine Achse frei drehbar ist
und auch in der Lage ist, sich zwischen einer Position, in welcher es den Riegel (6)
mechanisch angreift, und einer davon gelösten Position axial zu bewegen.
8. Einheit nach Anspruch 7, dadurch gekennzeichnet, daß in dem Zylinder (2) ein Elektromagnet
(31) vorgesehen ist, wobei der Kern (30) desselben radial zu dem Eingreifelement (12)
positioniert ist und zwischen zwei axial getrennten Positionen, nämlich mit Störung
bzw. ohne Störung des Eingreifelementes, bewegbar ist.
9. Einheit nach Anspruch 8, dadurch gekennzeichnet, daß das Eingreifelement (12) eine
Umfangsrippe (27) umfaßt, welche mit dem Kern (30) des Elektromagneten (31) zusammenwirkt,
wenn dieser sich in seiner Störungsposition befindet.
10. Einheit nach Anspruch 9, dadurch gekennzeichnet, daß mit dem Kern (30) des Elektromagneten
(31) eine Feder (50) verbunden ist, welche, wenn keine Anregung vorhanden ist, diesen
im Störungszustand mit der Umfangsrippe (27) hält.
11. Einheit nach Anspruch 7, dadurch gekennzeichnet, daß das Eingreifelement (12) an seinem
äußeren Ende mit Mitteln (32) für seine direkte mechanische Kopplung an den Schlüssel
(4) versehen ist, wenn dieser in den Zylinder (2) eingeführt ist.
12. Einheit nach Anspruch 9 und 11, dadurch gekennzeichnet, daß das Eingreifelement (12)
umfaßt:
- zwei Teile (52, 54), die relativ zueinander teleskopisch bewegbar sind, in Drehung
aber gegenseitig eingespannt sind, nämlich einen äußeren Teil (52), der mit den Mitteln
(32) zum direkten mechanischen Koppeln an den Schlüssel (4) versehen ist, und einem
inneren Teil (54), das mit einer perimetralen Rippe (27) versehen ist, und mit Mitteln
(36) zum direkten mechanischen Koppeln an den Riegel (6), wenn der Elektromagnetkern
von der perimetralen Rippe (27) gelöst ist,
- einen Stab (56), der unter der Steuerung des äußeren teleskopischen Teils (52) axial
bewegbar ist,
- eine erste Feder (14), die zwischen den teleskopischen Teilen (52, 54) angeordnet
ist,
- eine zweite Feder (58), die zwischen dem Stab (56) und dem Riegel (6) angeordnet
ist.
13. Einheit nach Anspruch 9 und 11, dadurch gekennzeichnet, daß das Eingreifelement (12)
umfaßt:
- zwei Teile (52, 54), die relativ zueinander teleskopisch bewegbar sind, aber in
Drehung gegenseitig eingespannt sind, nämlich ein äußeres Teil (52), das mit Mitteln
(32) zum direkten mechanischen Koppeln an den Schlüssel (4) versehen ist und einen
inneren Teil (54), der mit einer Umfangsrippe (27) versehen ist,
- einen Stab (56), der das Eingreifelement (12) axial durchquert und mit seinem äußeren
Ende dem äußeren Teil (52) entgegengerichtet ist und mit seinem inneren Ende dem inneren
Teil (54) entgegengerichtet ist,
- eine erste Feder (14), die zwischen den teleskopischen Abschnitten (52, 54) angeordnet
ist, und
- eine zweite Feder, die zwischen dem Stab (56) und dem Riegel (6) angeordnet ist.
14. Einheit nach Anspruch 12 und/oder Anspruch 13, dadurch gekennzeichnet, daß die Außenfläche
des Innenteils (54) des Eingreifelements (12) parallele Rippen umfaßt, die mit parallelen
Nuten zusammenwirken, welche in einer in dem Riegel (6) ausgebildeten, komplementären
Aufnahme für ihre gegenseitige Drehkopplung vorgesehen sind.
15. Einheit nach Anspruch 7, dadurch gekennzeichnet, daß in dem Zylinderhohlraum in dem
Zylinder (2) ein gezahnter Ring (16) aufgenommen ist, in welchem das Eingreifelement
(12) axial bewegbar ist, aber in Drehrichtung eingespannt ist, wobei der Ring (16)
mit dem Dauermagneten (18) mechanisch gekoppelt ist, wobei die Achse desselben rechtwinklig
zur Ringachse verläuft.
16. Einheit nach Anspruch 15, dadurch gekennzeichnet, daß der Ring (16) vorderseitig gezahnt
ist, wobei der Dauermagnet (18) einen gezahnten zylindrischen Abschnitt aufweist,
der in die vordere Zahnung des Ringes eingreift.
17. Einheit nach Anspruch 16, dadurch gekennzeichnet, daß der in dem Zylinder (2) für
den gezahnten Ring (16) vorgesehene Hohlraum eine Seitenwand mit einer leichten Verjüngung
(60) und einer gezahnten Stirnwand (62) aufweist.
18. Einheit nach Anspruch 1, gekennzeichnet durch das Vorhandensein eines Bolzens (64),
der mit dem Riegel (106) verbunden ist und mit einer längsgerichteten Aufnahme (66)
für den Schlüssel (104) versehen ist, mit einem Sitz für den Dauermagneten (118),
der während der Einführung des Schlüssels drehbetrieben wird, und einem beweglichen
Teil (76, 78, 84) für das gesteuerte Drehverriegeln des Bolzens (64) in bezug auf
den Zylinder (102).
19. Einheit nach Anspruch 18, dadurch gekennzeichnet, daß der Dauermagnet (118) mit einem
Ritzel (70) verbunden ist, das teilweise in die Aufnahme (66) des Bolzens (64) vorsteht
und mit einem in dem Schlüssel (104) vorgesehenen Eingreifteil (68) zusammenwirkt,
um die Drehung des Magneten (118) zu bewirken, wenn der Schlüssel in das Schloß eingeführt
wird.
20. Einheit nach Anspruch 18, dadurch gekennzeichnet, daß mit dem beweglichen Teil (76,
78, 84) der Kern (130) eines Elektromagneten (131) verbunden ist, was dazu führt,
das bewegliche Teil in eine Freigabestellung zu bringen, wenn die Erkennung des in
seine Aufnahme (66) des Bolzens (64) eingeführten Schlüssels (104) erfolgt ist.
21. Einheit nach Anspruch 18, dadurch gekennzeichnet, daß das Teil zum Drehverriegeln
des Bolzens (64) ein Paar zylindrischer Hohlelemente (76, 78) umfaßt, die zwischen
einer Verriegelungsposition, in welcher ein Element (78) die Drehung des Bolzens (74)
in seiner Aufnahme stört, und einer Freigabeposition, in welcher das Element (78)
in einer die Drehung des Bolzens (64) nicht störenden Position gehalten wird, bewegbar
sind, und umfaßt einen orientierten Dauermagneten (84), der in dem durch die Elemente
(76, 78) begrenzten axialen Hohlraum zwischen einer Verriegelungsposition, in deren
Übereinstimmung er an einem Abschnitt des Kerns (130) des Elektromagneten (131) anhaftet,
und einer Freigabeposition, in deren Übereinstimmung er von dem Elektromagneten (131)
in eine die Drehung des Bolzens (64) nicht störenden Position abgestoßen ist, unabhängig
bewegbar ist.
22. Einheit nach Anspruch 21, gekennzeichnet durch das Vorhandensein einer Feder (80),
die derart wirkt, daß sie das Paar zylindrischer Hohlelemente (76, 78) im Verrieglungszustand
hält, wobei eines (76) der Elemente teilweise in die Aufnahme (76) eindringt, die
in dem Bolzen (64) für den Schlüssel (104) vorgesehen ist.
23. Einheit nach Anspruch 21, dadurch gekennzeichnet, daß zu dem Element (78) des Paares
zylindrischer Elemente (76, 78) ein Gegenelement (82) aus ferromagnetischem Material
vorgesehen ist, dessen Kontaktfläche mit dem Dauermagneten (84) kleiner ist als die
Kontaktfläche mit dem Kern (130) des Elektromagneten (131).
1. Une unité à cylindre-clé à commande électromécanique pour serrures comprenant en combinaison
:
- un cylindre (2, 102) avec un doigt d'encliquetage (6, 106) pouvant tourner mécaniquement
par une clé (4, 104),
- une clé (4, 104) munie de son propre code d'identification et d'une logique de contrôle
(46, 146),
- un moyen de couplage électrique (40, 48, 140, 148) entre ladite clé (4, 104) lorsqu'elle
est insérée dans le cylindre (2, 102) et le cylindre lui-même,
- un aimant permanent (18, 118) logé dans ledit cylindre et pouvant être tourné par
la clé (4, 104),
- un circuit magnétique associé audit aimant permanent (18, 118),
- un enroulement (22, 122) logé dans le cylindre (2, 102) et relié audit circuit magnétique,
- un moyen (12, 64) pour réaliser sélectivement un couplage magnétique entre la clé
(4, 104) et le doigt d'encliquetage (6, 106),
- une logique de contrôle (26, 126) associée au cylindre (2, 102) et munie d'un code
d'identification pour ledit cylindre, et interagissant via ledit moyen de couplage
électrique (40, 48) avec la logique de commande (46, 146) de la clé (4, 104) lorsqu'elle
est insérée dans le cylindre,
- un élément électromécanique (30, 31, 130, 131, 76, 78) qui permet audit moyen (12,
64) de réaliser sélectivement la connexion mécanique à rotation entre la clé (4, 104)
et le doigt d'encliquetage (6, 106) sous la commande de ladite logique de commande
lors de la reconnaissance en correspondance entre les codes d'identification de ladite
clé et ledit cylindre respectivement, et
- un dispositif (24, 124) pour emmagasiner l'énergie électrique générée dans ledit
enroulement (22, 122), ledit dispositif (24, 124) étant électriquement connecté à
la logique de contrôle (26, 126) du cylindre (2, 102) au moins pendant la phase de
reconnaissance,
caractérisé en ce que :
- les moyens de couplage électrique (40, 48, 140, 148) entre la clé et le cylindre
(2, 102) sont des moyens de couplage électrique sans contact; et
- la logique de commande (26, 126) associée au cylindre (2, 102) est logée dans le
cylindre afin d'interagir avec la logique de commande (46, 146) de la clé via ledit
moyen de couplage électrique sans contact.
2. Une unité comme revendiqué dans la revendication 1, caractérisée en ce que la clé
(4, 104) est munie d'une antenne (48, 48) qui, lorsque la clé est insérée dans le
cylindre (2, 102), est couplée à l'antenne (40, 104) prévue dans la cavité cylindrique
du cylindre, lesdites antennes (40, 48, 140, 148) étant électriquement connectées
aux logiques de commande (46, 26, 146, 126) de la clé et du cylindre respectivement.
3. Une unité comme revendiqué dans la revendication 2, caractérisée en ce que l'antenne
(48, 148) de la clé (4, 104) et l'antenne (40, 140) du cylindre (2, 102) consiste
en des bobines coaxiales.
4. Une unité comme revendiqué dans la revendication 1, caractérisée en ce que ledit dispositif
d'emmagasinement (24, 124) est un condensateur.
5. Une unité comme revendiqué dans la revendication 1, caractérisée en ce que ledit dispositif
d'emmagasinement est une pile rechargeable.
6. Une unité comme revendiqué dans la revendication 1, caractérisée en ce que le moyen
de couplage (12) entre la clé (4) et le doigt d'encliquetage (6) sont du type à désengagement.
7. Une unité comme revendiqué dans la revendication 1, caractérisée en ce que le cylindre
(2) reçoit un élément de contact essentiellement cylindrique (12) qui est libre pour
tourner autour de son axe et également capable de se déplacer axialement entre une
position à laquelle il s'engage mécaniquement dans ledit doigt d'encliquetage (6)
et une position désengagée de celui-ci.
8. Une unité comme revendiqué dans la revendication 7, caractérisée en ce que dans le
cylindre (2) est prévu un électro-aimant (31), dont le noyau (30) est positionné radialement
par rapport à l'élément de contact (12) et est mobile entre deux positions distinctes
axialement, à savoir en coopération avec et en non-coopération avec ledit élément
de contact respectivement.
9. Une unité comme revendiqué dans la revendication 8, caractérisée en ce que l'élément
de contact (12) comprend une collerette circonférentielle (27) qui interagit avec
le noyau (30) dudit électro-aimant (31) lorsque celui-ci est à sa position de coopération.
10. Une unité comme revendiqué dans la revendication 9, caractérisée en ce qu'au noyau
(30) de l'électro-aimant (31) est associé un ressort (50) qui, lorsque l'excitation
est absente, le maintient dans l'état de coopération avec ladite collerette circonférentielle
(27).
11. Une unité comme revendiqué dans la revendication 7, caractérisée en ce que l'élément
de contact (12) est munie à son extrémité externe de moyens (32) pour son couplage
mécanique direct à la clé (4) lorsque celle-ci est insérée dans le cylindre (2).
12. Une unité comme revendiqué dans les revendications 9 et 11, caractérisée en ce que
l'élément de contact (12) comprend :
- deux parties (52, 54) mobiles téléscopiquement l'une par rapport à l'autre mais
mutuellement contraintes en rotation, à savoir une partie externe (52) munie desdits
moyens (32) pour le couplage mécanique direct à ladite clé (4) et une partie interne
(54) munie d'une collerette périmétrique (27) et de moyens (36) de couplage mécanique
direct audit doigt d'encliquetage (6) lorsque le noyau électromagnétique est désengagé
de la collerette périmétrique (27),
- une broche (56) mobile axialement sous la commande de ladite partie téléscopique
externe (52),
- un premier ressort (14) interposé entre lesdites parties télescopiques (52, 54),
et
- un deuxième ressort (58) interposé entre ladite broche (56) et ledit doigt d'encliquetage
(6).
13. Une unité comme revendiqué dans les revendications 9 et 11, caractérisée en ce que
l'élément de contact (12) comprend :
- deux parties (52, 54) mobiles télescopiquement l'une par rapport à l'autre mais
mutuellement contraintes en rotation, à savoir une partie externe (52) munie de moyens
(32) pour le couplage mécanique direct à ladite clé (4) et une partie interne (54)
munie d'une collerette périmétrique (27),
- une broche (56) traversant axialement ledit élément de contact (12) et ayant son
extrémité externe face à ladite partie externe (52) et son extrémité interne face
à ladite partie interne (54),
- un premier ressort (14) interposé entre lesdites parties télescopiques (52, 54),
et
- un deuxième ressort interposé entre ladite broche (56) et ledit doigt d'encliquetage
(6).
14. Une unité comme revendiqué dans la revendication 12 et/ou la revendication 13, caractérisée
en ce que la surface externe de la partie interne (54) de l'élément de contact (12)
comprend des collerettes parallèles coopérant avec des rainures parallèles ménagées
dans un siège complémentaire formé dans le doigt d'encliquetage (6) pour leur couplage
rotatif mutuel.
15. Une unité comme revendiqué dans la revendication 7, caractérisée en ce que à l'intérieur
de la cavité cylindrique dans ledit cylindre (2) est logé un anneau denté (16) dans
lequel ledit élément de contact (12) est axialement mobile mais contraint en rotation,
ledit anneau (16) étant couplé mécaniquement audit aimant permanent (18), dont l'axe
est perpendiculaire à l'axe de l'anneau.
16. Une unité comme revendiqué dans la revendication 15, caractérisée en ce que l'anneau
(16) est denté en face avant, l'aimant permanent (18) ayant une partie cylindrique
dentée engagée dans la denture avant dudit anneau.
17. Une unité comme revendiqué dans la revendication 16, caractérisée en ce que la cavité
ménagée dans le cylindre (2) pour l'anneau denté (16) a une paroi latérale avec un
léger cône (60) et une paroi d'extrémité dentelée (62).
18. Une unité comme revendiqué dans la revendication 1, caractérisée en ce qu'elle comprend
une fiche (64) associée au doigt d'encliquetage (106) et prévue avec un siège longitudinal
(66) pour la clé (104), avec un siège pour l'aimant permanent (118) fonctionnant en
rotation pendant l'insertion de la clé, et un élément mobile (76, 78, 84) pour le
verrouillage commandé en rotation de ladite fiche (64) par rapport audit cylindre
(102).
19. Une unité comme revendiqué dans la revendication 18, caractérisée en ce que l'aimant
permanent (118) est associé à un pignon (70), partiellement saillant dans le siège
(66) de la fiche (64) et coopérant avec une crémaillère (68) prévue dans la clé (104)
pour provoquer la rotation dudit aimant (118) lorsque la clé est insérée dans la serrure.
20. Une unité comme revendiqué dans la revendication 18, caractérisée en ce qu'à l'élément
mobile (76, 78, 84) est associé le corps d'un électro-aimant (131), qui est convenable
pour amener en état libéré ledit élément mobile, lorsque la reconnaissance de la clé
(104) insérée dans son siège (66) de la fiche (64) est survenue.
21. Une unité comme revendiqué dans la revendication 18, caractérisée en ce que l'élément
pour verrouiller en rotation la fiche (64) comprend une paire d'éléments creux cylindriques
(76, 78) mobiles entre une position de verrouillage, à laquelle un élément (78) coopère
avec la rotation de la fiche (64) dans son siège, et une position libérée, à laquelle
ledit élément (78) est maintenu en état de non-coopération avec la rotation de la
fiche (64) et comprend un aimant permanent orienté (84) mobile indépendamment dans
la cavité axiale limitée par lesdits éléments (76, 78) entre une position de verrouillage,
en correspondance de laquelle il adhère à une partie du corps (130) de l'électro-aimant
(131), et une position libérée en correspondance de laquelle il s'éloigne par répulsion
dudit électro-aimant (131) dans un état de non-coopération avec la rotation de la
fiche (64).
22. Une unité comme revendiqué dans la revendication 21, caractérisée en ce qu'elle comprend
un ressort (80) agissant de manière à maintenir la paire d'éléments creux cylindriques
(76, 78) en état de verrouillage, avec l'un (76) desdits éléments envahissant partiellement
le siège (66) prévu dans la fiche (64) pour la clé (104).
23. Une unité comme revendiqué dans la revendication 21, caractérisée en ce qu'à l'élément
(78) de la paire d'élément cylindrique (76, 78) est appliqué un élément contrastant
(82), réalisé en matériau ferromagnétique, dont la surface de contact avec l'aimant
permanent (84) est plus petite que la surface de contact avec le noyau (130) de l'électro-aimant
(131).