[0001] This invention is concerned with a locking device comprising a lock cylinder and
a flat key wherein the cylinder has a housing in which a cylinder plug is rotatably
accommodated together with a plurality of tumblers, the plug having a profiled keyway
into which the tumblers project in the locked condition of the device, and wherein
an additional tumbler is accommodated for sliding movement in a bore extending parallel
to the longitudinal centre plane of the keyway, said additional tumbler projecting
across the joint line between the plug and the housing when the device is in its locked
condition.
[0002] One such locking device is described in EP-A 202949. In this device not only does
the additional tumbler comprise an additional plug pin and an additional housing pin,
both of which have to be accommodated respectively in the plug and housing, and further
the plug pin has a relatively complex shape by which it can be operated, but also
a special construction of key is required which is relatively complex to manufacture.
Thus, while said device affords a high degree of security, nevertheless it is expensive
and time-consuming to manufacture.
[0003] It is the object of the present invention to provide an improved locking device wherein
the construction is considerably simplified without any significant loss in security.
[0004] This object is resolved, in accordance with the present invention, in a locking device
as set out in the first paragraph above, in that in a manner known per se there is
formed in one wide surface of the key, adjacent the back edge thereof, a longitudinally
extending recess one end of which opens into the key tip, and the longitudinal side
walls of which are, at their key tip ends, formed each with an outwardly inclined
run-in surface portion, a first of the surface portions running into the key tip and
the second being located rearwardly of the first, and in that the additional tumbler
has a projection which projects into the keyway and which is engaged in turn by the
two surface portions and is thus received in the recess formed in the key when the
latter is inserted in the keyway, the distance of the second surface portion from
the end, remote from the key tip, of the recess being greater than the dimension,
measured longitudinally of the keyway, of the projection, and the distance between
the side walls of the recess at said remote end thereof and the heightwise dimension
of the projection being such as to provide a close fit between the projection and
said end of the recess.
[0005] It will thus be appreciated that in the device in accordance with the present invention
the only additional manufacturing step associated with the key construction is a machining
operation to provide the recess and a relatively simple construction is required for
the additional tumbler with its projection. Nevertheless, the additional security
provided by the additional tumbler is not significantly diminished.
[0006] Various forms of recess may be provided in accordance with the present invention.
For example, the side walls of the recess may run straight, or alternatively the side
wall in which the first surface portion is formed may also have a re-entrant surface
portion intermediate said first surface portion and the remote end of the recess.
In this latter construction preferably the intermediate surface portion has a run-off
slope and the second surface portion, formed in the other side wall, is disposed opposite
said run-off slope.
[0007] Again, the side wall in which the second surface portion is formed may have a re-entrant
surface portion intermediate the second surface portion and the remote end of the
recess, and further the other side wall may have a corresponding recessed portion
disposed opposite thereto. With such an arrangement, furthermore, if desired a plurality
of additional tumblers may be provided, arranged one behind the other in the direction
of key insertion, and the heightwise disposition of each projection on its tumbler
is determined according to the position of the tumbler in the direction of key insertion
and thus its position in relation to the portion of the recess with which it co-operates
in the opening condition of the device (viz. when the key is inserted).
[0008] In order to control the heightwise movement of the additional tumbler with reliability
and certainty, preferably the two side walls provide a parallel-walled guide path
for the projection.
[0009] Using the locking device in accordance with the invention, it will thus be appreciated
that, when the key is inserted into the keyway of the cylinder, firstly the projection
is engaged by the first run-in surface portion of the key and is lifted, together
with the additional tumbler, during continued key insertion. As the key continues
to be inserted, the second run-in surface portion then engages the projection, at
the other side thereof, and ensures that it is cammed against the side wall in which
the first surface portion is formed. At this stage the heightwise disposition of the
tumbler is fully controlled, without the need for springs or other devices common
in lock constructions. The projection is now held in the parallel-walled guide path
and remains under control for the remainder of the key insertion, at the end of which
the tumbler has freed the cylinder, which is thus now in its opening condition.
[0010] Conveniently the second surface runs into the back edge of the key. Furthermore,
preferably the bore in which the additional tumbler is accommodated opens at both
ends into the surface of the plug, the length of the additional tumbler corresponding
to the length of the bore and the projection being spaced from one end of the additional
tumbler such that, in the opening condition of the device, the additional tumbler
is accommodated wholly within the bore. In this way, it will be appreciated, it is
not necessary to provide a separate plug pin and housing pin for the additional tumbler,
but rather a single pin is sufficient.
[0011] As is conventional in many keys, a guide groove may extend longitudinally of the
key adjacent the back edge thereof. In accordance with the present invention, furthermore,
preferably this guide groove passes through, but is deeper than, the recess. In this
way, the guide groove still can serve its function without interfering in any way
with the operation of the recess, and further without the recess and projection having
any detrimental effect on the guidance of the key.
[0012] It will be appreciated that in the locking device in accordance with the invention
rotation of the plug and insertion of an unauthorised key is advantageously prevented
in the region of the guidance groove. Using such a device furthermore, the key firstly
retains its unitary construction but on the other hand makes an extensive profile
variation possible. The arrangement of grooves and ribs on the wide sides of the key
remains unaffected, since the operation controlling the projection takes place exclusively
in the generally most solid region of the flat key, namely the back. Also it is sufficient
if a quite small part of the key length is used for the recess. On the other hand,
however, further variations in respect of the depth of insertion can be achieved without
detriment. In addition, the mode of construction is both simple and practical.
[0013] In use, the appropriately arranged inclined run-in surface portions are effective,
when the key is inserted, forcibly to operate the projection. Thus there is no requirement
for means, e.g. springs or the like, whereby a particular end position is determined.
Nevertheless the function is highly certain. Compared with keys having the same overall
construction from the point of view of the locking system used, the modification is
scarcely noticeable. The offset of the first run-in surface portion from the tip of
the key is quite small. Usual keys having the same locking function and profile would
on the other hand collide with the projection, producing a barring effect, since their
tip is relatively thicker in the direction of insertion. Modification of the key tip,
however, e.g. to avoid operating the additional tumbler, would result not only in
failure to release the latter, but also in prevention of the operation of the cylinder
cam (or thrower), quite apart from difficulties in initial insertion of the key and
in the normal operation of the tumbler pins.
[0014] By the feature of the second run-in surface portion running into the back edge of
the key, furthermore, the control function of this second edge begins at a zero position,
viz. in the plane of the joint line end of the cylinder plug, which is advantageous
in terms of the control of the heightwise disposition of the additional tumbler.
[0015] It is also favourable that the depth of the recess is smaller than that of the guidance
groove passing therethrough. In this way no grooving beyond the usual amount arises
at the recessed wide face of the key because of the recess; the key blade thus retains
its stability.
[0016] There now follows a detailed description, to be read with reference to the accompanying
drawings, of three exemplary embodiments of the present invention. It will of course
be understood that these three embodiments have been selected for description merely
by way of non-limiting example.
[0017] In the accompanying drawings:-
Figs. 1 and 2 show in side view a locking cylinder and an associated flat key;
Figs. 3 and 4 are views in plan of the cylinder and key shown in Figs. 1 and 2;
Fig. 5 is a fragmentary view on an enlarged scale of the tip end of the key, in a
first embodiment of the invention, showing also a projection of an additional tumbler
of the cylinder;
Fig. 6 is a section taken along the line VI-VI of Fig. 5;
Fig. 7 is a view in section taken along the line VII-VII of Fig. 1, showing the additional
tumbler in a locking condition;
Fig. 8 is a view similar to Fig. 7, but with the key inserted and the cylinder in
consequent opening condition;
Fig. 9 is a view similar to Figs. 7 and 8 but with the additional tumbler in an intermediate
position;
Figs. 10 to 12 are respectively side, front and underneath plan views of the additional
tumbler;
Fig. 13 is a view, similar to Fig. 5, but of a key in accordance with a second embodiment
of the invention;
Fig. 14 is a view in section taken along the line XIV-XIV of Fig. 13;
Fig. 15 is a view, similar to Figs. 5 and 13, but of a key in accordance with a third
embodiment of the invention; and
Fig. 16 is a view in section taken along line XVI-XVI of Fig. 15.
[0018] Referring to Figs. 1 to 4, the lock cylinder 1 shown is a double cylinder having
a cylinder housing 2 which supports in a middle section 3 a cam (or thrower) 4. In
each of the two opposed housing sections, of which one is only partially shown, a
cylinder plug 5 is journalled and is connected to the cam upon insertion of a key
6. The intermediate connection element (not described in detail) is engaged by the
insertion-end tip Sp of the key blade 7 to operate it. Each cylinder plug 5 (one only
of which is hereinafter described) has a keyway 8 suited to the cross-sectional profile
of the key. Radially disposed plug pins 9 project into the keyway, being aligned,
when the flat key 6 is removed, with housing pins 10 which are urged by compression
springs 11 in the direction of the cylinder plug 5. In the embodiments five such tumblers
are provided for each cylinder plug.
[0019] The blade 7 of the flat key 6 has on both wide sides profiled variation grooves 12
extending in the direction of key insertion and profile variation ribs 13 adjacent
thereto. Extending in opposed relation to the back edge 14 of the key blade 7, which
is matched accurately to the cylindrical shape of the cylinder plug 5, are V-cuts
15 of different depths. The axial distance between the bottom of adjacent cuts is
however the same in each case. All the V-cuts 15 end spaced from a guide section of
the key blade 7 in the zone of which, near to the back, extends a continuous guide
groove 16. A base 26ʹ of the latter extends right into the region of a longitudinal
central plane A-B of the flat key blade 7, which plane also corresponds to the like-designated
plane of symmetry of the locking device.
[0020] The tip Sp of the key blade 7 is, as can be seen in the drawings, cut in a peak-shape
such that two diverging end surfaces, including an angle of less than 90°, lie adjacent
a slightly convex-shaped first zone forming the tip Sp, the upper of which end surfaces
runs into the back edge 14 and the lower into the start of the first V-cut.
[0021] The tip end region of the guide groove 16 (see Fig. 5) has formed therein a widened
portion or recess E which is open up to the tip Sp. For co-operating with said recess
E a projection N is arranged on an additional tumbler 17 which faces the key blade
7, said projection projecting transversely into the keyway 8. The additional tumbler
17 is accommodated in a bore 18 of the cylinder plug 15, which bore runs parallel
to the longitudinal centre plane A-B of the keyway 8. For operating the additional
tumbler 17 the recess E has two outwardly inclined run-in surface portions, each leading
into a side wall of the recess. More particularly, the key tip end of one side wall
19 of the recess E, lying at the V-cut side of the recess, has formed therein a first
inclined run-in surface portion I, the angle of inclination of which is about 45°.
The key tip end
a of this surface portion I is in planar alignment with the underside 20 of the projection
N, or lies slightly therebeneath. This basic orientation of the additional tumbler
17 is defined by supporting the underside 20 of the projection N on a bottom edge
21 of a cut-out 22 formed in the cylinder plug 5 (see Fig. 7), which cut-out intersects
the keyway 8. In this position (corresponding to the locked condition of the device)
both the conventional tumblers, formed from the plug pins 9 and housing pins 10, and
also the additional tumbler 17, intersect the lock cylinder joint line F, the lower
end 17ʹ of the additional tumbler projecting into a locking recess 23 formed in the
cylinder housing 2 and lying on the same axis as the bore 18. The locking recess 23
is machined through an aligned bore 24 provided in the cover of the cylinder housing
2, which bore can then be plugged.
[0022] Since said end
a of the first run-in surface portion I extends rearwardly in relation to the arched
peak
b (see Fig. 5) forming the key tip Sp, a flat key of otherwise the same type would,
without the recess E, collide with the corresponding vertical side surface 25 of the
projection N; such a key would thus be barred.
[0023] The key tip end of the other side wall of the recess E has formed therein a second
run-in surface portion II, disposed at a greater distance from the tip Sp than the
first surface portion I. The distance
y of said second surface portion II from the end 26, remote from the key tip, of the
recess E is greater than the dimension, measured in the direction of key insertion,
of the projection
N. The end 26 of the recess E forms an end cut-out designated Eʹ, which is rounded
off, e.g. to conform to a rounded projection shape (not shown in detail). In the first
embodiment the projection N is generally rectangular in cross-section with bevels
27 formed at the edges, the bevel engaging the end
a of the first surface portion I enabling the additional tumbler 17 to be operated
smoothly.
[0024] In the third embodiment illustrated in Figs. 15 and 16 the two run-in surface portions
I, II form a reception funnel which is closely adjacent to the tip and from which
the recess E extends with straight parallel sides up to the end 26. The first embodiment
shown in Fig. 5, on the other hand, has a more complex arrangement in that the side
wall forms in combination with the first run-in surface portion I a guide path having
a re-entrant portion 19 lying more closely to the back edge 14 of the key 6. The guide
path thus runs into the end cut-out Eʹ of the recess E, running parallel to the second
run-in surface portion II, and indeed is arranged first descending and then extending
straight. This shape therefore operates in altogether three planes. The first plane,
which allows the key to move beneath the projection N by virtue of the end
a of the first surface portion I, runs into a higher plane defined by the wall portion
19. In this position an upper end 17ʺ of the additional tumbler 17 enters the bore
24 of the cylinder housing cover. The guide path then has a descending portion defined
by a run-off surface portion 28, which runs parallel with the second surface portion
II, the guide path thus leading to the end cut-out Eʹ, which forms the third plane
in which the additional tumbler 17 no longer projects beyond the lock cylinder joint
line F (see Fig. 8). The lower end 17ʹ of the additional tumbler 17 is cut back at
the inner side 17‴ (see Figs. 10 to 12) so that the pointed zone does not hook on
the corresponding edge of the hole of the locking recess 23. The cylinder plug 5 is
now rotatable. As can be seen in Fig. 8, the distance of the projection N from the
upper end surface of the additional tumbler 17 is of the same dimension as the heightwise
distance of the guide path from the back edge of the key.
[0025] The second embodiment (Figs. 13 and 14) differs from the aforedescribed merely in
that the end cut-out Eʹ of the recess E rises again in the region of the end 26; the
guide path is thus wave-shaped in this case. As can be seen the recess E extends over
a region of two V-cuts 15. In this case, therefore, two or even more additional tumblers
17 may be provided, lying one behind the other in the direction of insertion of the
key 6, and each having a projection N; the distance by which, in the opening condition,
each projection lies from the back edge 14 is thus determined by its position along
the keyway. The planes associated with said tumblers are designated C-D and G-H and
are disposed on lands between the conventional tumblers 10/11. The lower section of
the guide path lying between the side wall portion 19 and the end cut-out Eʹ is embraced
by a trapezoidal bridge 29, thus providing the wave contour. In this way moreover
the amount of material remaining is substantial, so that practically no weakening
of the end region of the flat key arises, since the recess E does not in any event
extend up to the base 16ʹ of the guide groove 16. In this way also visually the key
retains an appearance corresponding to that of similar keys, because the guide rib
structure is partially continued.
[0026] In using any one of the keys described above, upon insertion thereof the projection
N of the additional tumbler 17 is raised and, when the key is fully inserted, is held
by closed-fitted guidance in opening condition. When the key is withdrawn, on the
other hand, the gravity-dependent additional tumbler 17 moves into a locking condition,
thus barring rotation by projecting beyond the lock cylinder joint line F. The introduction
of a generally similar key which does not have the recess E is barred since the tip
Sp collides with the side 25 of the projection N so that insertion of the key is prevented
and the additional tumbler 17 cannot be lifted.
1. A locking device comprising a lock cylinder (1) and a flat key (6) wherein the
cylinder (1) has a housing (2) in which a cylinder plug (5) is rotatably accommodated
together with a plurality of tumblers (9,10), the plug (5) having a profiled keyway
(8) into which the tumblers (9) project in the locked condition of the device, and
wherein an additional tumbler (17) is accommodated for sliding movement in a bore
(23) extending parallel to the longitudinal centre plane (A-B) of the keyway (8),
said additional tumbler (17) projecting across the joint line between the plug (5)
and the housing (2) when the device is in its locked condition,
characterised in that in a manner known per se there is formed in one wide surface
of the key (6), adjacent the back edge thereof, a longitudinally extending recess
one end of which opens into the key tip (Sp), and the longitudinal side walls of which
are, at their key tip ends, formed each with an outwardly inclined run-in surface
portion (I,II), a first (I) of the surface portions (I,II) running into the key tip
(Sp) and the second (II) being located rearwardly of the first (I),
and in that the additional tumbler (17) has a projection (N) which projects into the
keyway (8) and which is engaged in turn by the two surface portions (I,II) and is
thus received in the recess (E) formed in the key (6) when the latter is inserted
in the keyway (8), the distance (y) of the second surface portion (II) from the end
(Eʹ), remote from the key tip (Sp), of the recess (E) being greater than the dimension,
measured longitudinally of the keyway (8), of the projection (N), and the distance
(x) between the side walls of the recess (E) at said remote end (Eʹ) thereof and the
heightwise dimension of the projection (N) being such as to provide a close fit between
the projection (N) and said end (Eʹ) of the recess (E).
2. Device according to Claim 1 characterised in that the side walls of the recess
(E) run straight.
3. Device according to Claim 1 characterised in the side wall in which the first surface
portion (I) is formed also has a re-entrant surface portion (19) intermediate said
first surface portion (I) and the remote end (Eʹ) of the recess (E).
4. Device according to Claim 3 characterised in that the intermediate surface portion
(19) has a run-off slope (28) and in that the second surface portion (II), formed
in the other side wall, is disposed opposite said run-off slope (28).
5. Device according to Claim 1 characterised in that the side wall in which the second
surface portion (II) is formed has a re-entrant surface portion (29) intermediate
said second surface portion (II) and the remote end (Eʹ) of the recess (E) and in
that the other side wall has a corresponding recessed portion disposed opposite thereto.
6. Device according to Claim 5 characterised by a plurality of additional tumblers
(17) arranged one behind the other in the direction of key insertion, and in that
the heightwise disposition of each projection (N) on its tumbler (17) is determined
according to the position of the tumbler (17) in the direction of key insertion and
thus its position in relation to the portion of the recess (E) with which it co-operates
in the opening condition of the device.
7. Device according to any one of the preceding Claims characterised in that the two
side walls provide a parallel-walled guide path for the projection (N).
8. Device according to any one of the preceding Claims characterised in that said
second surface portion (II) runs into the back edge (14) of the key (6).
9. Device according to any one of the preceding Claims characterised in that the bore
(23) in which the additional tumbler (17) is accommodated opens at both ends into
the surface of the plug (5), in that the length of the additional tumbler (17) corresponds
to the length of the bore (23), and in that the projection (N) is spaced from the
one end of the additional tumbler (17) such that, in the opening condition of the
device (viz. when the key (6) is inserted), the additional tumbler (17) is accommodated
wholly within the bore (23).
10. Device according to any one of the preceding Claims wherein a guide groove (16)
extends longitudinally of the key (6) adjacent the back edge (14) thereof, characterised
in that the guide groove (16) passes through, and is deeper than, the recess (E).