The present invention relates to a cylinder lock/key combination
of the kind defined in the preamble of Claim 1. The invention also relates to a
key and to a key blank of the kind defined in the preambles of Claims 6 and 10,
Cylinder locks of the kind in which the key slot accommodates in
the rotational centre of the lock plug an element which makes the insertion of
a lock-picking tool difficult to achieve, and keys that are designed for use with
such locks, are known for instance from DE-C-36 12 38 (Bergmann), DE-C-6 42 131
(Hermann Bode in Hannover), US-A-877,930 (Katzenberger) and FR-A-2,525,267 (Toutain).
One common drawback with these constructions is that if the tumbler
pins housed in the cylinder and the plug need to be changed, for instance when
re-coding the lock or because one or more tumblers have been damaged, this change
cannot be effected conventionally in the actual place where the lock is fitted.
A slot-carried element of the aforesaid kind fitted axially in the
key slot of the plug affords the advantage of making the insertion of a lock-picking
tool into the key slot difficult. However, because of the difficulty in carrying
out on-site tumbler changes with the aid of a tool of the kind referred to, this
type of lock has been unsuccessful commercially, despite being difficult to pick.
A tumbler change often requires the use of a tool which can be passed
through the plug from beneath. The tool is used to force the tumblers out of their
respective chambers, so as to enable a new set of tumblers and associated springs
to be inserted and the tumbler chambers in the cylinder closed.
The cylinder and the fitted plug is then ready to be fitted in place
for continued use, optionally together with a new key if it has been found necessary
to re-code the lock as a result of changing tumbler pins.
DE-C-217 799 (Hartmann) describes a padlock whose key includes a
bore or recess whose profile can vary in accordance with the profile shape of a
pin element provided in the lock and onto which the key is inserted. This pin element
is non-rotatable and forms a key turning centre.
US-A-1,932,706 (Neer) describes a lock construction that includes
a central key journalling centre having a round shape. The key code has the form
of a screw-thread.
US-A-1,477,318 (Crass) describes a type of lock which includes a
slot-carried element wherein the coding shall face downwards in order for the key
to be inserted into the key opening in the plug. The key is thus profiled only
in the actual inlet to the plug. The key does not lift the tumbler pins as it
is inserted into the lock, and the lock is therefore of the lever tumbler kind,
i.e. a lock in which the tumbler pins are not activated until the key is turned.
The slot-carried element forms a bearing, i.e. a centre for rotation of the key.
The preamble of the following Claim 1 includes features that are characteristic
of this known lock.
In this lock, the slot-carried element referenced 16 in Figs. 2 and
5 forms a stop surface which supports the tumbler pins in the absence of a key
in the lock. That part of the key which embraces the slot-carried element is thick
and has a regular shape. This means that the lock can be easily picked by inserting
a lock-picking tool into the keyhole in the absence of a key.
FR,A1,2 565 281 (Construzioni Italiane Serature Affini) describes
a lock/key combination having the features stated in the preamble of claim 1, i.e.
it is of a type where the blade part of the key is not turnable relative to or
within the key slot. The key has in section a part formed as the figure "4" and
the key slot has a corresponding configuration to receive the key. An axially extending
wedge or strip portion ("nervure") of the plug fills a recessed part of the key
blade and contributes to define part of the key slot. The pins are also recessed
to receive part of the key blade including its bottom code with the intention to
make the part of the pins actuated by the code unaccessible to a picking tool.
OBJECTS OF THE INVENTION
One object of the present invention is to provide a cylinder lock/key
combination which includes a slot-carried element and which is an improvement on
earlier known combinations, and with which the slot-carried element can be given
a novel function, namely a function of enabling keys to be produced with very
thin, curved and irregular profiled parts which make picking of the lock with a
lock-picking tool difficult to accomplish.
Another object of the invention is to provide a cylinder lock/key
combination which includes a slot-carried element which is able to coact with a
tumbler pin replacement tool which can be used to remove all tumblers in the plug
and the cylinder respectively after being inserted, despite the fact that the
slot-carried element makes picking of the lock difficult to accomplish.
Another object of the invention is to provide a cylinder lock/key
combination where the key has a novel and modified profiled shape.
SUMMARY OF THE INVENTION
These and other objects are fulfilled by an inventive lock/key combination
having the features set forth in the characterizing clause of Claim 1, and by the
inventive key and key blank having the features set forth in the characterizing
clause of claims 6 and 10 respectfully. There has been created a novel concept
in the manufacture of lock and key combinations which is distinguished from the
known technique in which the slot-carried element is located in the rotation centre
of the plug and the key respectively and which does not normally rotate together
with the plug, even though this is possible in accordance with the known technique,
- a) the slot-carried element is positioned excentrically and is removably fitted
in the key slot, or keyhole, and accompanies its rotation;
- b) the slot-carried element can thereby be given a different and novel function,
namely the function of enabling the manufacture of keys that have very thin, curved
and irregular profiled parts which make picking of the lock with a lock-picking
tool difficult to accomplish;
- c) illegal copying of a key is made difficult, among other things because conventional
key blanks lack sufficient thickness to leave a sufficiently thick region of material
on one or both sides of the slot-carried element after having formed the hole or
the recess that receives the slot-carried element; and by the fact that
- d) a pin-removal tool of conventional design can be used despite the presence
of the slot-carried element.
It can also be mentioned in this regard that serious limitations
are found with respect to the manufacture of conventional keys with regard to the
profiled shape and thickness of the key blade. This limitation is related to the
broach or drawing tool used to shape the key slot or the hole (bore).
The broach is weak so that no accuracy or precision can be maintained
when part of the cross-section of the slot becomes too thin.
For instance, in practice no cross-sectional measurement of the key
slot may be smaller than 0.8-1 mm, which is thought to be the thinnest section
The present invention eliminates this limitation with regard to producing
the key slot in the plug and in producing a corresponding key blade profile.
Instead, the key slot can be made abnormally broad in the region
of the spine or bottom edge of the key, which is a positive criterion with regard
to the broaching tool. Application of the bore slot-carried element which coacts
with the axial hole, bore or recess provided in the key enables relevant profiled
parts of the key blade adjacent the hole or recess to be made unusually thin, which
results in the aforesaid particular advantages afforded by the inventive lock/key
combination without having serious consequences with regard to the use of a broach
tool in connection with the key slot formed in the plug.
The fact that the slot-carried element can be removed from the plug
after removing the lock cylinder from the lock housing facilitates the aforedescribed
exchange of tumbler pins on the user site, for instance in conjunction with changing
the code of the cylinder lock. At the same time, it is ensured that the slot-carried
element cannot be removed, for instance by a person attempting to pick the lock.
In this regard, the slot-carried element is mounted excentrically
on an end plate which is fitted removably to the plug.
An inventive cylinder lock/key combination preferred in practice
in which the plug includes a row of tumbler pins whose axes in one starting position
of plug rotation in which a tumbler dividing plane is formed between tumblers accommodated
in the core and in the lock cylinder, lie in a symmetry plane through the centre
of the plug is characterized in that an axially extending line through the slot-carried
element and the centre region of the hole or recess lies on one side of said symmetry
In other words, the excentrically located slot-carried element may
be placed on one side of a symmetry plane that extends through the centre of the
tumblers in that row of tumblers with which the coded surface of the key coacts
and through the geometrical axis of the plug.
Although not necessary, the slot-carried element may be round. For
instance, the slot-carried element may have a square, rectangular or polygonal
cross-sectional shape as an alternative to a round shape. Furthermore, it lies
within the concept of the invention to use a slot-carried element which has an
irregular or asymmetric cross-sectional shape, even though this would lead to difficulties
in providing the key with a hole of corresponding profiled shape.
It is preferred in practice that the slot-carried element has a diameter
or largest thickness of between 1 and 3 mm. It is also preferred that the width
of the key slot in the region of the spine or bottom of the key is of the order
of 3-3.5 mm.
The walls that define the element-receiving hole or recess in the
key may include projections and/or hollows which give the key a form that is difficult
It is best in practice for the key to include a round hole which
receives the slot-carried element as the key is inserted into the key slot in the
plug. The key blade of a key provided with such a hole will have the requisite
stiffness, even though the walls defining the hole, or bore, are thin. This is
therefore the preferred key design. However, it also lies within the concept of
the invention to provide the key with a recess which extends along the key blade
and in which the slot-carried element is received, instead of a hole. The function
of the recess corresponds to the function of a hole, despite not being completely
encased by material. This design reduces the stiffness of the key blade part,
although this can be compensated for by producing the key from a more robust material,
optionally a resilient material.
The slot-carried element extends suitably along a substantial part
of the length of the slot.
The invention also relates to the key of a combination of the aforesaid
kind. The main characteristic features of such a key are set forth in Claims 6-9.
A key blank from which such a key can be produced is defined in Claim 10.
According to one preferred embodiment, the material that defines
the hole is relatively thin, at least in parts, e.g. has a thickness of less than
1 mm, suitably less than 0.7 mm and preferably less than 0.5 mm.
It is not normally possible to produce a key-slot part whose thinness
corresponds to a key-part that has a thickness of only 0.4 mm, for instance. As
mentioned in the aforegoing, it is impossible in practice to produce these slot
parts with a corresponding small thickness when using a broach. This problem is
eliminated in a surprisingly simple manner when using a slot-carried element design
in accordance with the invention. The relevant region of the key slot is broached
with a tool of normal thickness or of a thickness larger than normal. Because
of the presence of the slot-carried element, those parts of the key that embrace
said element can be given said very small thickness.
It thus lies within the scope of the invention to give the key a
more or less scrolled form which varies within wide limits, where certain parts
of the scroll have very small thicknesses.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described in more detail with reference
to exemplifying embodiments thereof and also with reference to the accompanying
drawings, in which
DESCRIPTION OF PREFERRED EMBODIMENTS
- Fig. 1 is a perspective illustration of an inventive cylinder lock and associated
- Fig. 2 is a perspective view of a dismountable end plate which is fitted on
the cylinder of a cylinder lock according to Fig. 1 and which is provided with
an excentrically mounted slot-carried element;
- Fig. 3 is a partly cut-away front view of the cylinder lock shown in Fig. 1;
- Figs. 4 and 5 are front views of alternative embodiments corresponding to Fig.
3, in which the slot-carried element is laterally offset and has a round and a
square cross-sectional shape respectively;
- Fig. 6 is a partially cut-away side view of a cylinder lock according to Fig.
- Fig. 7 is a perspective view of a key blank from which the key shown in Fig.
1 can be made.
A cylinder lock/key combination includes a lock cylinder 2, a plug
3 rotatably mounted in the cylinder, and an associated key 5.
The plug 3 includes a key slot 4 and a number of tumbler pins 6 which
can be activated or shifted by the coding 5a on the key 5. Disposed in the key
slot 4 along the whole of its length, or along a substantial part of its length,
is an axially extending element 7, which may have a varying profile.
The key 5 also includes a grip part 5b and a coded blade part 5c,
an axially extending part 5d, and a hole or bore 8 which extends along the part
5d and which receives the slot-carried element 7 as the key is inserted into the
The slot-carried element 7 and the hole 8 in the key 5 are disposed
excentrically in relation to the centre of the plug 3 and accompany rotational
movement of the plug, aided by the key 5.
As shown in Fig. 2, the slot-carried element is mounted excentrically
on an end plate 9 which can be attached removably to the cylinder 2. The slot-carried
element can thus only be removed when dismantling the cylinder 2 from the lock
In the embodiment shown in Figs. 1 and 3, the slot-carried element
lies in a vertical symmetry plane through the lock cylinder. The element 7 is disposed
excentrically in relation to the plug, i.e. the axis of said element 7 extends
parallel with and above the centre line of the plug 3.
As shown in Fig. 4, the plug 3 has disposed therein a row of tumbler
pins 6 whose axes lie in a symmetry plane of the plug centre when in the illustrated
starting position of plug. Insertion of the key 5 therewith provides a tumbler
pin parting plane between the upper tumbler pins in the plug 3 and the lower tumbler
pins in the cylinder 2.
It will be seen from Figs. 4 and 5 that an axial line through the
centre region of the slot-carried element 7 and the hole 8 lies on one side of
said symmetry plane, i.e. the slot-carried element 7 extends parallel with the
centre line of the plug but is offset laterally in relation thereto.
The material defining the hole 8 is thin, and in practice may have
a thickness of about 0.4 mm.
In the case of the embodiments illustrated in Figs. 1-4, the slot-carried
element 7 and the corresponding hole 8 in the key 5 are round. The slot-carried
element may have a diameter of between 1 and 3 mm.
In the case of the Fig. 5 embodiment, the slot-carried element has
a square cross-section. The thickness of said element may vary correspondingly,
i.e. from between 1 and 3 mm.
As will be evident from the aforegoing, the profiled shape of the
slot-carried element may vary within wide limits and the element may optionally
have an asymmetrical or fully irregular shape.
The width of the key slot 4 in the region of the spine or bottom
part 5e of the key may be 2.5 mm as a maximum, although the width is often smaller
in practice, e.g. about 2 mm.
In the case of the embodiments illustrated in Figs. 1, 2, 4 and 6,
in which the slot-carried element has a round cross-section, the axial hole 8 in
the key 5 will suitably have a diameter which slightly exceeds the diameter of
the element 7.
The blade or shank part 5c of the key in which the axial hole 8 is
formed may have a more or less scrolled configuration, the thickness of these hole-defining
parts being smaller than 0.5 mm, for instance 0.4 mm, as before mentioned.
Fig. 7 is a perspective view of a key blank 5' from which the key
5 shown in Fig. 1 can be produced. The key blank includes a grip part 5'b, a blade
part 5'c a bottom or spine part 5'e and a part 5'd in which an axial hole 8 is
provided for receiving a slot-carried element 7. The hole 8 is located excentrically
in relation to the centre line of a plug 3 with which a key 5 produced from said
blank is intended to coact. Top portion 5'a of blank 5' extends in the same plane
as grip part 5'b.