Field of the Invention
Present invention relates to a cylinder lock for a vehicle. In particular, present invention relates to a cylinder lock with a protection device.
Background
Cylinder locks are generally used in a vehicle to provide a locking system in the vehicle. Generally, a cylinder lock may provide for locking of the steering handle and ignition switch. As the cylinder locks may be subject to tampering by a thief or children, the cylinder locks are provided with a protection device for preventing unauthorized access to the cylinder lock. Such protection devices generally include a plate arranged to cover the key-hole of the cylinder lock when the cylinder lock is not in use. Such mechanism involves a mechanism where a metal plate is arranged to move over the keyhole by use of suitable gears, which are actuated by the user using a separate key.
Such assemblies for cylinder lock protection device are very bulky and involve a number of components. Accordingly, the cylinder lock protection device known in the art unnecessarily occupy more space on the vehicle. Therefore, there is a need for cylinder lock with protection device which requires less space on the vehicle.
Present disclosure is adapted to address one or more problems as discussed above and other problems associated with the art.
Summary
A protection device for an ignition lock of a cylinder lock is provided. The protection device has a case configured for mounting over a rotor of the ignition lock and a rotary shutter mounted on the case. The rotary shutter is rotatable relative to the case. Further, the rotary shutter has a first rib extending from a cylindrical outer surface of the rotary shutter. A rotor head is configured for placing on and
2

engaging the rotor to rotate together with the rotor. The rotor head further defines a keyhole opening for providing access to the rotor. A sliding shutter is placed slidably in a shutter recess defined by the rotor head. The sliding shutter has a head adapted to selectively cover the keyhole opening and a shank extending from the head. The rotary shutter is rotarily movable between a shut condition wherein the first rib engages the shank of the sliding shutter to retain the head in a position covering the keyhole opening, and an open condition wherein the first rib moves away from the shank to allow movement of the head away from the keyhole opening.
In an aspect, the ignition lock is movable between a locked position and an unlocked position, the protection device is adapted to move in shut condition when the ignition lock is in locked condition.
In an aspect, the rotary shutter defines a short rib and the rotor head defines a second rib, the second rib adapted to engage the short rib to prevent movement of rotary shutter from open condition to shut condition when the ignition lock is in unlocked condition.
In an aspect, the sliding shutter is biased to cover the keyhole opening.
In an aspect, the sliding shutter is biased using a spring placed between the rotor head and the sliding shutter such that one end of the spring abuts the head and the other end abuts the rotor head.
In an aspect, the case defines a magnet housing for holding key magnets and the rotary shutter is mounted rotatably over the magnet housing, the rotary shutter being adapted for operation with a magnet key.
In an aspect, the rotor defines engagement slots and the rotor head is provided with corresponding protrusions for engagement of the rotor with the rotor head.

In an aspect, the protection device has a crimp plate adapted for placing over the rotor head to retain the sliding shutter in the shutter recess, the crimp plate defines a key slot for insertion of a key into the keyhole opening.
In an aspect, the rotor head defines a third rib extending from the outer cylindrical outer surface of the rotor head. The third rib is adapted to engage the case to retain the rotor head on the casing.
In an aspect, the protection device hasa cover mounted over the case. The cover and the case are configured to provide a housing for other components of the protection device.
In an aspect, the case has a cylindrical portion defining a cylindrical cavity to receive the rotor and an extension plate extending from the cylindrical portion. The extension plate is adapted for mounting of the rotary shutter.
In an aspect, the case has stoppers to restrict angular movement of the rotary shutter to a predetermined angle.
In an aspect, the head is provided with a taper for guiding insertion of a key inside the keyhole opening.
A cylinder lock having a protection device is disclosed herein.
Brief Description of Drawings
FIG. 1 illustrates a perspective view of a cylinder lock, a protection device and a key in accordance with an embodiment of the present disclosure. FIG. 2 illustrates a perspective exploded view of the protection device in accordance with an embodiment.

FIG. 3 illustrates a top view of the case of the protection device in accordance with
an embodiment.
FIG. 4 illustrates a front view of the case of FIG. 3.
FIG. 5 illustrates a perspective view of the rotary shutter in accordance with an
5 embodiment.
FIG. 6 illustrates a top view of the rotor head in accordance with an embodiment.
FIG. 7 illustrates a front view of the rotor head of FIG. 6.
FIG. 8 illustrates a bottom view of the rotor head of FIG. 6.
FIG. 9 illustrates a top view of the sliding shutter in accordance with an
10 embodiment.
FIG. 10 illustrates a front view of the sliding shutter of FIG. 9.
FIG. 11 illustrates a bottom view of the sliding shutter of FIG. 9.
FIG. 12 illustrates a top view of the cylinder lock (without cover and crimp plate)
with the protection device in the shut condition.
15 FIG. 13 illustrates a top view of the cylinder lock of FIG. 12 with the protection
device in the open condition.
FIG. 14 illustrates a top view of the cylinder lock with ignition lock in off position.
FIG. 15 illustrates a top view of the cylinder lock with ignition lock in on position.
20 Detailed Description
A cylinder lock 10 with a protection device 12 is disclosed. The protection device 12 protects the cylinder lock 10 from any unauthorized access or tampering. The cylinder lock 10 may be configured for locking or unlocking a steering handle and switching on/off an ignition circuit of a vehicle such as two-wheeled motor-cycle,
25 or a three-wheeled motorized vehicle. The cylinder lock 10 may also be configured
for operation of any locking or unlocking mechanism or for switching of an electronic circuit of the vehicle. For example, the cylinder lock 10 may be configured for controlling of any other devices such as seat lock, boot space lock, fuel tank lock, lights, etc.
30
FIG. 1 illustrates the cylinder lock 10 having an ignition lock 14 and the protection
5

device 12. FIG. 1 further illustrates a key 16that can be used to operate the cylinder
lock 10. As illustrated, the key 16 has an ignition key 18 which may be used for
operation of the ignition lock 14 and a magnet key 20 which may be used for
operation of the protection device 12. In the embodiment as illustrated, a single key
5 16 is shown having provision to operate both, the ignition lock 14 and the protection
device 12. It may be understood that in an alternate embodiment two separate keys may be used to operate the cylinder lock 10 and the protection device 12.
As shown in FIG. 1 the ignition lock 14 has a rotor 22 towards its top portion 23.
10 The ignition lock 14 may be configured for mounting of the protection device 12on
the ignition lock 14. The rotor 22 has two engagement slots 24 towards the top portion 23. The use and configuration of these two engagement slots 24 will be explained later in the description.
15 As shown in FIG. 2, the protection device 12 has a case 26, a cover 28, a crimp
plate 30, a rotor head 32, a sliding shutter 34, a rotary shutter 36 and springs 38. The case 26supports or houses other components of the protection device 12 as described later. Referring to FIG. 3 and FIG. 4, the case 26 may have a cylindrical portion defining a cylindrical cavity 40oriented vertically and configured to receive
20 the rotor 22 of the ignition lock 14 through the cylindrical cavity 40 when the case
26 is mounted over the ignition lock 14, such that the top portion 23 of the rotor 22 partially extends out form the upper end of the cylindrical cavity 40.The portion of the case26 surrounding the cylindrical cavity 40 may be configured for mounting on the ignition lock 14positioned below the case 26 and configured for mounting
25 the cover 28 which is mounted towards an upper portion of the case 26.
Further, as shown in FIG. 3 and FIG. 4, the case 26 may have an extension plate 42
extending in a plane substantially perpendicular to the axis 43 of the cylindrical
cavity 40. The extension plate 42 supports the components associated with the
30 rotary shutter 36. The extension plate 42 further has other configurations necessary
for the overall working of the protection device 12 as described herein. The
6

extension plate 42 has a magnet housing 44 extending vertically from the extension
plate 42. As shown in FIG. 3, the magnet housing 44 may have one or more magnet
recesses 46defined on its top surface for insertion of key magnets (not shown). The
key magnets may be inserted in a predetermined configuration or combination
5 corresponding to the key magnets that may be provided in the magnet key 20, as
known in the art, such that the magnet key 20 and the protection device work based
on the matching of configuration of the key magnets in the magnet key 20 and the
protection device 12. The rotary shutter (36) is locked by the magnets and it is
allowed to rotate only when the correct magnet key (20) is inserted in the key recess
10 (54) of rotary shutter (36). In the embodiment as illustrated, the magnet housing 44
is cylindrical in shape.
Further, as shown in FIG. 3 and FIG. 4, the extension plate 42 is provided with a first stopper 48 and a second stopper 50, both extending vertically from the
15 extension plate 42 proximate to the magnet housing 44. The stoppers48 and 50 may
be in the form of studs extending from the extension plate 42. As described later herein, the first stopper 48 and the second stopper 50 restrict or limit an angular movement of the rotary shutter 36 in both clockwise and anti-clockwise direction to a predetermined angle.
20
Further, the case 26may be provided with suitable provision for mounting of the cover 28 over the case 26. For example, in the embodiment illustrated herein, screw holes 52 are provided on the extension plate 42 and the cover 28 may be provided with female threads (not shown) on its bottom portion, and fasteners may be
25 inserted through the screw holes 52 from the bottom side of the extension plate 42
to mount the cover 28 over the case 26. The case 26 and various provisions of the case 26 may be made of any suitable material such as metal or polymer. Further, it may be understood that the provisions of the case 26 as explained herein may be made either integrally with the case 26 or may be separate components attached to
30 the case 26.
7

The rotary shutter 36 may be of substantially cylindrical shape and has a cylindrical
recess (not shown) at its bottom portion which corresponds to the cylindrical shape
of the magnet housing 44. The shape of the magnet housing 44 and the cylindrical
recess are designed such that when the rotary shutter 36 is placed over the magnet
5 housing 44, the cylindrical recess receives the magnet housing 44 to allow a rotary
motion of the rotary shutter 36 relative to the magnet housing 44. The axis of
rotation of the rotary shutter 36 may be substantially parallel to the axis 43 of the
cylindrical cavity 40 or to the axis of rotation of the rotor 22. The axis of rotation
of the rotor 22 may be perpendicular to the plane in which extension plate 42
10 extends.
The rotary shutter 36 is configured to form-fittingly receive the magnet key 20. The top end 37 of the rotary shutter 36 may define a key recess 54 that corresponds to the shape of the magnet key 20 such that when the magnet key 20 is inserted in the
15 key recess 54, the rotary movement of the magnet key 20 results in rotary motion
of the rotary shutter 36. The rotary shutter is movable between a shut condition and an open condition. Further, a floor 56 of the recess, that defines the bottom of the key recess 54 may be configured for positioning on and nearly abutting the top of the magnet housing 44 when the rotary shutter 36 is placed on the magnet housing
20 44. The thickness of the floor 56 defines the top of the cylindrical recess of the
rotary shutter 36. Accordingly, the floor 56 is positioned over the magnet housing 44 in an assembled state of the protection device 12. The material and/or the thickness of the floor 56 may be designed such that the floor 56 does not substantially affect the interaction of the magnets in the magnet housing 44 and the
25 corresponding magnets of the magnet key 20 when in operation.
Further, the rotary shutter 36 is provided with a first rib 58 running circularly along
a length of and extending from the cylindrical outer surface of the rotary shutter 36.
The stoppers 48 and 50 are positioned on the extension plate 42 such that the
30 stoppers fall in path of movement of the first rib when the rotary shutter 36 is rotated
over the magnet housing. Thus, the first stopper 48, the second stopper 50 and the
8

first rib 58 are configured such that when the rotary shutter 36 is rotated the first
stopper 48 and the second stopper 50 restrict the rotary or angular movement of the
rotary shutter 36 beyond a certain angle. Further the rotary shutter 36 has a short
rib 60. The short rib 60 may be positioned vertically above the first rib 58. The
5 circular length of the short rib 60 is substantially shorter than the circular length of
the first rib 58. The function and configuration of short rib 60 is discussed later herein.
Referring to FIG.s 6-8, the rotor head 32 is configured for mounting on the top
10 portion 23 of the rotor 22. As shown in FIG. 8, the bottom portion the rotor head 32
may have a recess that is configured to receive the top portion 23 of the rotor 22.
Further, the bottom portion of the rotor head 32 may have two protrusions 62
extending from the bottom surface of the rotor head 32. The shape and size of the
protrusions 62 may be configured to form-fittingly engage with the engagement
15 slots 24 provided on the rotor 22. The protrusions 62 are received in the engagement
slots 24 such that rotor head 32 and the rotor 22 engage each other rotate together.
Further, the rotor head 32 is provided with a shutter recess 64 on the top portion as shown in FIG. 6. The shutter recess 64 is shaped such that the shutter recess 64 has
20 a head portion 66 and a shank portion 68. The head portion 66 is positioned within
the outer boundaries of the rotor head 32 and a keyhole opening 70 is provided for insertion of the ignition key 18 at an end of the head portion 66 away from the shank portion 68 of the shutter recess 64. The shank portion 68 starts from the other end of the head portion 66 and extends through the lateral outer boundary of the rotor
25 head 32. The shank portion 68 may also extend through the bottom portion of the
rotor head 32 as well, as shown in FIG. 6 and FIG. 8. Further, the rotor head 32 has shoulders 82 positioned at the transition of the head portion 66 to the shank portion 68 to guide the sliding shutter 34 during its movement inside the recess 64.
30 The rotor head 32 is provided with a second rib 72 and a third rib 74. Both, the
second rib 72 and the third rib 74 run circularly along and extend from the
9

cylindrical outer surface of the rotor head 32 as shown in FIG.s 6-8. In the
embodiment as illustrated the second rib 72 is positioned vertically offset to the
third rib 74. Also, the second rib 72 and the third rib 74may be vertically spaced
with respect to each other on the outer surface of the rotor head 32. The circular
5 length and positioning of the first rib 58, the second rib 72 and the third rib 74 may
be ascertained according to intended operation of the cylinder lock 10 as described later in the description.
The sliding shutter 34 is configured to be placed in the shutter recess 64 of rotor
10 head 32. As can be seen in FIG.s 9-11, the sliding shutter 34 has a head 76, a shank
78 and spring recesses 80. In assembly, the sliding shutter 34 is placed in the shutter recess 64 such that the head 76 is placed in the head portion 66 and the shank 78 is placed in the shank portion 68 of the shutter recess 64.
15 The sliding shutter 34 is placed such that the spring recesses 80 face towards the
rotor head 32 so that the springs 38may be secured in the spring recesses 80between the sliding shutter 34 and the rotor head 32. Further, the sliding shutter 34 is shaped such that when placed in the shutter recess 64, the sliding shutter 34 can slide inside the shutter recess 64 with the shank portion 68 sliding in and through the shank
20 portion 68 and the head 76 slides in the head portion 66 of the shutter recess 64.
The springs 38 placed in the spring recesses 80 abut the sliding shutter 34 at one and to the shoulders 82 at the other end. This way the springs 38 bias the head 76 of the sliding shutter 34 away from the shank portion 68 of the shutter recess 64 such that in absence of other external force, an edge 84 of the head 76 abuts the
25 rotor head 32. The placement of the sliding shutter 34 along with the springs 38 on
the rotor head 32 can be seen in FIG.2 and FIG.s 12-15.
The rotor head 32 and the sliding shutter 34 are configured such that when the edge
84 of the head 76 abuts the rotor head 32,the access to the rotor through the keyhole
30 opening 70 is closed and on movement of the edge 84 of the sliding shutter 34 away
from the rotor head 32, access to the rotor through the keyhole opening 70 opens
10

for insertion of ignition key 18. Further, the shape and size of the head 76 and the
head portion 66 of the shutter recess 64 can be configured such that the sliding
shutter 34 is allowed to move between a shut condition and an open condition,
wherein in the open condition, sufficient enough space is provided by the sliding
5 shutter 34 for insertion of ignition key 18 in the keyhole opening 70. It may be
understood that in open condition the space between the edge 84 of the sliding shutter 34 and the rotor head 32is configured such that on rotation of the ignition key 18, the rotor head 32 rotates along with the ignition key 18. Also, the space may be kept limited so that when the key is placed in the ignition lock 14, dust and other
10 foreign materials may be prevented from entering the keyhole opening 70. Further,
it may be understood that since the sliding shutter 34 is biased by the springs 38, the edge 84 of the sliding shutter 34 will tend to abut the surface of the shaft of the ignition key 18 when ignition key is inserted and will readily close the keyhole opening 70 as soon as the ignition key 18 is removed from the keyhole opening 70.
15
Referring to FIG. 2, the protection device 12 may further have a crimp plate 30. The crimp plate 30 may be configured for mounting on the top of the rotor head 32 for guiding the shaft key into the rotor 22of the ignition lock 14. A key slot 86 may be provided on the crimp plate 30 to guide the ignition key 18 into the rotor 22of
20 the ignition lock 14. The crimp plate 30 may further have cutouts corresponding to
the second rib 72 and the shank portion 68 of the shutter recess 64in order to allow snug fit of the crimp plate 30 over the rotor head 32 and simultaneously allow movement of the shank 78 of the sliding shutter 34 through the shank portion 68. The crimp plate 30 also ensures the sliding shutter 34 is retained in the shutter recess
25 64 after assembly of the cylinder lock 10. The crimp plate 30 may be made of a
sheet of a metal such as stainless steel or may be made of any other suitable material. Other than guiding the shaft key into the rotor, the crimp plate 30 may have other associated known advantages such as protection of the ignition lock 14 from dust or water.
30
11

The cover 28 secures the components of the cylinder lock 10 in their place and
prevents entry of dust in the cylinder lock 10. Further, the cover 28 may be provided
with suitable markings or indicators for indication of different positions or modes
of the cylinder lock 10 and the protection device 12 for enabling easy operation by
5 a user, as illustrated in FIG. 1 and FIG. 2. The cover 28 may have appropriate
openings 88 for providing access for inserting the ignition key 18 and magnet key 20 for operation of the cylinder lock 10 as shown in FIG. 2. In the embodiment as illustrated, the cover 28 has circular openings.
10 Assembly of the cylinder lock 10 can be done as follows. The ignition lock 14 is
ensured in the lock position. Then the case 26 is placed over the ignition lock 14 such that the rotor 22is received through the cylindrical cavity 40 of the case 26. Then rotor head 32 may be placed over the rotor 22such that the protrusions 62 of rotor head 32 match and are received in the engagement slots 24 provided on the
15 rotor, and the rotary shutter 36 is placed over the magnet housing 44. The third rib
74 of the rotor head 32 abuts the case 26 in assembled condition and prevents the rotor head 32 from being completely received in the cylindrical cavity 40. It may be understood that magnets are placed in the magnet recesses 46 before placing the rotary shutter 36 over the magnet housing 44. While placement of the rotary shutter
20 36, the first rib 58 is positioned towards the rotor head 32 and the first rib 58 is
positioned between the first stopper 48 and the second stopper 50. Now the sliding shutter 34 may be placed in the shutter recess 64 along with the springs 38. After placing the sliding shutter 34, the crimp plate 30 may be placed over the rotor head 32 to secure the sliding shutter 34 in the shutter recess 64. Finally, the cover 28 may
25 be placed and fastened over the over case 26in order to secure all the components
on the case 26 in place. It may be understood that the manner and sequence of assembly as described above is exemplary and slight change in configuration of the components of the cylinder lock 10 may require corresponding changes in the manner and sequence of assembly of the cylinder lock 10.
30
12

In assembled state the shank 78 at least partially extends outwards from the outer boundary of the rotor head 32 as shown in FIG.s 12-15. Further, in assembled state, the shank 78 and the first rib 58 lie in same horizontal plane. Similarly, in assembled state, the second rib 72 and the short rib 60 lie in same plane. 5
The working of the various components along with the working and configurations of the first rib 58, the second rib 72 and the short rib 60, and operation of the cylinder lock 10 are illustrated in FIG.s 12-15 and described as follows. FIG. 12 illustrates the cylinder lock 10 in the shut condition. In shut condition, the ignition
10 lock 14 is in lock position, i.e. handle of the vehicle is in locked condition, and the
rotary shutter 36 is in shut condition. The first rib 58 abuts the first stopper 48 at one end. In shut condition, the first rib 58 restricts the motion of the sliding shutter 34 as the movement of the shank 78 is restricted by the first rib 58 to retain the head of the sliding shutter in a position covering the keyhole opening. Accordingly, in
15 shut condition a user cannot insert the ignition in the keyhole opening 70 as the
sliding shutter 34 keeps the keyhole opening 70 closed.
FIG. 13 illustrates the cylinder lock 10 in the open condition. For switching the cylinder lock 10 from the shut condition to open condition, a user may insert the
20 magnet key 20 in the key recess 54 of the rotary shutter 36 and rotate the rotary
shutter 36 clockwise to the open condition, i.e. until the second stopper 50 abuts the first rib 58 and restricts further movement of the rotary shutter 36. In open condition, the first rib 58 gets away from the path of the sliding shutter 34 to allow movement of the head away from the keyhole opening and uncover the keyhole
25 opening. Accordingly, a user may insert the shaft of the ignition key 18 in the
keyhole opening 70 by pushing the shaft of the key through edge 84 of the sliding shutter 34.
The edge 84 of the sliding shutter 34 may be provided with a taper 90 to facilitate
30 guiding of the shaft in the keyhole opening 70. Similarly, the rotor head 32 may be
provided a taper 90 near the keyhole opening to facilitate easy guided insertion of
13

ignition key 18 in the keyhole opening 70. Also, the taper 90 may act as a cam surface for moving the edge 84 of the sliding shutter 34 away from the rotor head 32 against the biasing force of the springs 38 and consequently allow insertion of the ignition key 18 into the keyhole opening 70 and inside the rotor. Once the key is inserted, the user may rotate the key clockwise to switch the ignition lock 14 from locked condition to off position or unlocked condition, as shown in FIG. 14. Further, after off position is achieved, the user may further switch the ignition lock 14 in on position. Both, the off position and the on position of the ignition lock are referred to as unlocked condition.
As illustrated in FIG. 14, in off position, the second rib 72 comes proximate to the rotary shutter 36. The positioning of the second rib 72 is such that the short rib 60 nearly abuts the second rib 72. This relative positioning of the short rib 60 and the second rib 72 ensures that the rotary shutter 36can not be rotated back to the shut condition, as the second rib 72 restricts anti-clockwise movement of the short rib 60 and consequently restricts anti-clockwise movement of the rotary shutter 36. This arrangement ensures that a user does not forget to put the ignition lock 14 in locked position before switching the cylinder lock 10 in shut condition.
As seen in FIG. 15, which illustrates the cylinder lock 10 in on position, in on position, the second rib 72 still nearly abuts the short rib 60 of the rotary shutter 36. Therefore, the user can still not switch the cylinder lock 10 in shut condition. Accordingly, it is ensured that a user can switch the cylinder lock 10 in shut condition only when the cylinder lock 10 is in locked position, i.e. only after steering handle of the vehicle is locked. This way a false shut condition is prevented.
It may be understood that the shape, size and positioning of different components and their features may be slightly altered to achieve same results with substantially similar components and their features. Such insubstantial modifications are intended to be within scope of the present disclosure. Also, it may be understood

that the components of the cylinder lock lOand the protection device 12as described herein may be made of any suitable material such as metal or plastic.
The present disclosure provides for a cylinder lock 10 with protection device 12 that has various advantages over known cylinder locks and protection devices. The cylinder lock 10 with the protection device 12 in accordance with present disclosure eliminates use of a sliding shutter 34 plate that requires more space. Consequently, the protection devicel2 of the present disclosure does not require use of any gears for rotation of any sliding plate. Thus, overall assembly in accordance with present disclosure is compact and simple. Further, the cylinder lock 10 in accordance with the present disclosure also prevents any false shut conditions as described above.

List of Reference Numerals
Cylinder lock 10
Protection device 12
Ignition lock 14
Key 16
Ignition Key 18
Magnetic Key 20
Rotor 22
Top portion (Rotor) 23
Engagement slots 24
Case26
Cover 28
Crimp plate 30
Rotor head 32
Sliding shutter 34
Rotary shutter 36
Top end (Rotary shutter) 37
Springs 38
Cylindrical cavity 40
Extension plate 42
Axis (Cylindrical cavity) 43
Magnet housing 44
Magnet recesses 46
First stopper 48
Second stopper 50
Screw holes 52
Key recess 54
Floor 56
First rib 58
Short rib 60

Protrusions 62 Shutter recess 64 Head portion 66 Shank portion 68 Keyhole opening 70 Second rib 72 Third rib 74 Head 76 Shank 78
Spring recesses 80 Shoulders 82 Edge 84 Key slot 86 Openings 88 Taper 90

CLAIM:
A protection device (12) for an ignition lock (14), the protection device (12) comprises:
a case (26) configured for mounting over a rotor (22) of the ignition lock (14),
a rotary shutter (36) mounted on the case (26), the rotary shutter (36) being rotatable relative to the case (26); the rotary shutter (36) having a first rib (58) extending from a cylindrical outer surface of the rotary shutter (36);
a rotor head (32) configured for placing on and engaging the rotor (22) to rotate together with the rotor (22), the rotor head (32) defining a keyhole opening (70) for providing access to the rotor (22);
a sliding shutter (34) placed slidably in a shutter recess (64) defined by the rotor head (32), the sliding shutter (34) having a head (76) adapted to selectively cover the keyhole opening (70) and a shank (78) extending from the head (76);
the rotary shutter (36) being rotarily movable between:
a shut condition wherein the first rib (58) engages the shank
(78) of the sliding shutter (34) to retain the head (76) in a position
covering the keyhole opening (70); and
an open condition wherein the first rib (58) moves away from
the shank (78) to allow movement of the head (76) away from the
keyhole opening (70).
The protection device (12) as claimed in claim 1, wherein the ignition lock (14) is movable between a locked position and an unlocked position, the protection device (12) adapted to move in shut condition when the ignition lock (14) is in locked condition.
The protection device (12) as claimed in claim 1, wherein the rotary shutter (36) defines a short rib (60) and the rotor head (32) defines a second rib (72), the second rib (72) adapted to engage the short rib (60) to prevent

movement of rotary shutter (36) from open condition to shut condition when the ignition lock (14) is in unlocked condition.
4. The protection device (12) as claimed in claim 1, wherein the sliding shutter (34) is biased to cover the keyhole opening (70).
5. The protection device (12) as claimed in claim 4, wherein the sliding shutter (34) is biased using a spring (38) placed between the rotor head (32) and the sliding shutter (34) such that one end of the spring (38) abuts the head (76) and the other end abuts the rotor head (32).
6. The protection device (12) as claimed in claim 1, wherein the case (26) defines a magnet housing (44) for holding key magnets and the rotary shutter (36) is mounted rotatably over the magnet housing (44), the rotary shutter (36) being adapted for operation with a magnetic key (20).
7. A protection device (12) as claimed in claim 6, wherein the rotary shutter (36)
is locked by the magnets and it is allowed to rotate only when a correct magnet key (20) is inserted in the key recess (54) of rotary shutter (36).
8. The protection device (12) as claimed in claim 1, wherein the rotor (22) defines engagement slots (24) and the rotor head (32) is provided with corresponding protrusions (62) for engagement of the rotor (22) with the rotor head (32).
9. The protection device (12) as claimed in claim 1, comprising:
a crimp plate (30) adapted for placing over the rotor head (32) to retain the sliding shutter (34) in the shutter recess (64), the crimp plate (30) defining a key slot (86) for insertion of a key (16) into the keyhole opening
(70).

10. The protection device (12) as claimed in claim 1, wherein the rotor head (32) defines a third rib (74) adapted to engage the case (26) to retain the rotor head (32) on the case (26).
11. The protection device (12) as claimed in claim 1, comprising:
a cover (28) mounted over the case (26); the cover (28) and the case (26) configured to provide a housing for other components of the protection device (12).
12. The protection device (12) as claimed in claim 1, wherein case (26) has a cylindrical portion defining a cylindrical cavity (40) to receive the rotor (22) and an extension plate (42) extending from the cylindrical portion, the extension plate (42) adapted for mounting of the rotary shutter (36).
13. The protection device (12) as claimed in claim 1, wherein the case (26) has stoppers (48, 50) to restrict angular movement of the rotary shutter (36) to a predetermined angle.
14. The protection device (12) as claimed in claim 1, wherein the head (76) is provided with a taper (90) for guiding insertion of a key (16) inside the keyhole opening (70).
15. A cylinder lock (10) having a protection device (12) as claimed in claim 1.