CYLINDER LOCK This invention relates to an improvement of cylinder locks of the type which comprises a plug with a key channel, a housing surrounding the plug and an intermediate sleeve provided between the plug and the housing and adapted to be rotated about the same axis as the plug, as well as a number of through bores for locking pins being divided and adapted to be shifted in their longitudinal direction in the bores by means of a key inserted in the key channel. The invention in particular is directed to providing a cylinder lock having substantially increased security against unauthorized tampering in attempts of non-permitted intrusion by opening a door being locked. A particular form for tampering in this connection is a method involving the use of a key blank and successively by simultaneously applying a strong torque and bending of the key blank, for causing the various bottom or tumbler pins in the cylinder lock to emboss more or less weak markings on the key blank. Thereafter these markings can be used for filing down the blank and gradually approximating "towards the correct key which makes it possible to open the lock. In expert circles the method is referred to as "impressioning".

Numerous proposals are previously known, directed to improving the security in lock designs. As examples reference can be made to European patent application publication No. 212.468, GB patent application No.2.222.201, SE published application No. 427.483 and US patents Nos. 4.351.171, 1.434.483 and 2.295.737, and more specifically US patents Nos. 4.386.510, 3.990.281 and 4.282.731 as well as European patent application No. 06765.

US patent 3.990.281 is of interest since it aims at the prevention of tampering by "impressioning", and in principle

involves functions which to some extent are similar to the solution according to the present invention.

On the background of this prior art, perhaps in particular as represented by US patent 4.282.731, this invention provides a cylinder lock the novel and specific features of which consist primarily in the combination that each of the locking pins is divided into a bottom pin, a number of thin dividing pins, a code pin and an upper pin, for establishing a first shear surface between the plug and the sleeve and a second shear surface between the sleeve and the housing upon insertion of a correct key, that the sleeve has a radial dimension being sufficiently large to accommodate the whole length of a code pin and a portion of an upper pin, that the thin dividing pins are located between each code pin and an associated bottom pin, that an additional bore for a separate auxiliary pin is provided in the housing and the sleeve, adapted to be engaged by surfaces on the plug so that the blocking effect of the auxiliary pin with respect to the sleeve in relation to the housing, is released when the plug is rotated through a given angle in relation to the sleeve, and that drive means in a manner known per se is adapted to transfer rotational movement of the plug beyond said given angle, into movement of a blocking member for a lock, for example a locking bolt. Additional specific features and advantages of the invention will appear from the following description with reference to the drawings, in which:

Fig. 1 shows a schematic longitudinal section through a cylinder lock according to an embodiment of the invention.

Fig. 2 shows a schematic cross section along the line

II-II in fig. 1, Fig. 3 shows in principle another embodiment according to the invention, in cross section, Fig. 4 shows a partial and enlarged cross section of a detail of the embodiment in fig. 3,

Fig. 5 shows in schematic longitudinal section corresponding to fig. 1, a third embodiment according to the invention,

Fig. 6 shows a longitudinal section perpendicular to the section according to fig. 5, and

Fig. 7 shows a schematic cross section along the line V I-V I in fig. 5.

Figures 1 and 2 show the common components of the cylinder lock in the form of a plug 1, a housing 3 and a number of locking pins located in bores 11 - 17 , whereby the assembled locking pin in bore 11 nearest to the opening of the key channel 2, is denoted 21.

As shown with respect to locking pin 21 each locking pin comprises several parts, including an upper ^" pin ^' 21A being under the influence of a compression spring 21C, and a tumbler or bottom pin 2IB which has a somewhat pointed lower end adapted to be engaged by the various faces or bits on a key being inserted into the key channel 2. The particular subdivision and the other parts of the locking pins in fig. 1 shall be discussed more closely below.

A hollow cylindrical intermediate sleeve 5 is arranged to be rotatable between the housing 3 and the plug 1. The mutual rotation between these three parts will of course depend upon the position of the locking pins in bores 11 - 17, all these penetrating from housing 3 through sleeve 5 and into plug 1.

As a result of the provision of sleeve 5, which plays a substantial role for the locking function, there are established two surfaces or levels for possible divisions or sheares so that a plug 1 and sleeve 5 respectively, can be rotated in relation to each other and in relation to housing 3, provided that a correct positioning of the individual locking pins 11 - 17, is brought about by insertion of a correct key. What is essential, however, for an increased security in this connection, is an auxiliary

pin 20 consisting of an upper part 20A and a lower part 2OB both of which in similarity to the other pin parts, are under the influence of a compression spring in its bore 19. Normally the auxiliary pin 20 (in the position shown in fig. 1) will block sleeve 5 against rotation in relation to housing 3. When, however, a key is used which releases plug 1 for rotation in relation to sleeve 5, a cut-away part IB which is engaged by auxiliary pin part 2OB will be displaced by rotation so that the end of pin part 20B upon rotation through a sufficient angle (see fig. 2) will engage the actual cylindrical periphery of plug 1. Since the length of the lower part 2OB of auxiliary pin 20 is equal to the radial thickness of sleeve 5 this also leads to the release of sleeve 5 for rotation in relation to housing 3. Such continued rotation of sleeve 5 by using a correct key, is adapted to bring about the actual movements of the blocking member of the lock, for example a locking bolt. An axial stud 9 at the end of sleeve 5 is provided for this purpose. At the inner end of plug 1 there is a drive mechanism 7 which transfers the torque from an inserted key through plug 1 to sleeve 5 when the above blocking by auxiliary pin 20 is removed. It is just this required angle of rotation between plug 1 and sleeve 5 for displacing auxiliary pin 20, which to a substantial degree eliminates the possibility of the particular form of tampering which was discussed at the beginning of this description.

Moreover it is obvious that the two shear surfaces being established at the inside and at the outside respectivly of sleeve 5, makes it possible to code the locking pin assembly in a high number of different ways. Each such locking pin 21 thus comprises a particular code pin 2ID and a number of dividing pins 2IE between the code pin and the bottom pin 2IB. Whereas the upper pin 21A normally has the same length in all bores 11 - 17, the bottom pin 2ID advantageously can have one of two

predetermined lengths, which in combination with individually selected lengths of the respective code pins, constitutes the total key code which can be implemented in each individual lock. As will appear in particular from fig. 2, the cut-away face IB which co-operates with auxiliary pin 20 is a plane surface, but it is obvious that this surface can be shaped in various manners in order to perform its cam-like function. Fig. 2 further shows in a schematic way how a divided locking pin is raised by means of a key inserted in the key channel 2. Besides fig. 2 shows more in detail a device for releasable mutual fixation of plug 1 and sleeve 5 in. a normal angular position or central position. A projecting member in the form of a ball 25 lies in a bore 26 in plug 1 under the influence of a compression spring 27 and can be pressed out to engage a groove 28 in the surrounding sleeve 5. Obviously this arrangement could be inverted, i.e. with ball 25 lying at the end of a bore in the sleeve for engaging a groove or a depression in plug surface 1A. This positioning device serves to bring sleeve 5 back to its normal central position when the key is turned back after opening the lock.

It is obvious that a cylinder lock according to the principles of figs. 1 and 2 can be provided with internal steel rods or the like so as to make it difficult to break the lock by boring holes at different points, in particular in the area of the locking pins. In this connection it is an advantage to locate the auxiliary pin 20 axially innermost in the lock, i.e. as far as possible away from that side of the lock which is accessible, namely to the left in fig. 1, where the opening into the key channel 2 is found.

The embodiment in fig. 3 specifically aims at saving space and makes it possible to employ the improved design according to the invention, also in a type of lock of a

certain standard which is available commercially. The actual lock housing 33 here has a generally oval shape with a width which is not much larger than the diameter of the plug 31 of the lock. The intermediate sleeve here has the shape of a hollow cylindrical sector 35 which may be considered cut out from a complete hollow cylinder as shown in figs. 1 and 2. The sector-shaped sleeve 35, however, comprises the parts of such a sleeve which are essential to the function described. Even though locking pins and an auxiliary pin have not been indicated in fig. 3, these are provided in a manner fully corresponding to what is found in the embodiment of figs. 1 and 2. Housing 33 in fig. 3 has a cavity or chamber which covers an angular range between side walls 37A and 37B so that sleeve 35 can move within these limitations. In this particular embodiment the blocking effect of the auxiliary pin between housing 33 and sleeve 35 is released upon a rather small angular displacement from the central position. Thus at 3IB there is indicated a form of incision in the cylinder surface 31A which in contrast to cam face IB on the plug 1 in figs. 1 and 2, has a very short extension along the periphery, with an associated small operational angle as mentioned above. This has a relationship to the reduced total rotational movement which is possible in the embodiment of fig. 3. Thus in this embodiment it is the plug 31 itself which carries the drive member for transferring rotation from an inserted key through plug 31 directly to a blocking member for the locking function, for example a locking bolt. In the embodiment of fig. 3 an additional pin is required, as shown in the enlarged cross-sectional view of fig. 4. Radially through the intermediate sleeve 35 there is provided a bore 41 for a pin 40 which by means of a compression spring 42 is urged radially outwards against the inner cylindrical surface of the surrounding housing 33. In the angular position shown in fig. 4 the inner end 40A of pin 40 engages a short peripheric groove 31C in plug surface

31A, so that this engagement makes the sleeve 35 rotate together with plug 31 when a correct key has been inserted and is turned. When, however, this rotation has brought the pin into a certain angle (at the right in fig 4) to a recess 33A in the cylindrical surface of the housing, pin 40 will be pressed out and the above engagement in the peripheric groove 31C is terminated. Apparently this will take place when the aforementioned small angle determined by the cam face and/or the incision 3IB has been exceeded, but before sleeve 35 abutts against the side wall 37B of the chamber in housing 33. When plug 31 has become free to be further rotated in relation to sleeve 35, a sufficient rotation can be performed by the plug in order to cause the required movement of the blocking member in the lock. The embodiment of figs. 3 and 4 in practice will be considered somewhat less secure than the embodiment of figs. 1 and 2, but anyhow will be completely useful in many instances, in particular when the question of space and the commonly used standard locks with associated lock casing and so forth are taken into consideration. In principle, however, the embodiment of figs. 3 and 4 will give the same protection against the particular 'form of tampering ("impressioning") as the embodiment first described above. Figs. 5, 6 and 7, however, show a further embodiment which represents an improvement in relation to the one in figs. 1 and 2 as far as security is concerned. The improvement is related to a specific solution regarding the auxiliary pin and its function.

In figs. 5, 6 and 7 there is again a plug 51, an intermediate sleeve 55 and a housing 53 as well as other components found in the embodiment of figs. 1 and 2, including a number of locking pins 51A-F. Instead of a separate radial auxiliary pin in line with the locking pins as in figs. 1 and 2, the embodiment of figs. 5, 6 and 7 has an auxiliary pin 60 lying in principle parallel to the axis of the plug. More particularly this auxiliary pin is

located with the main portion of its length in a bore in the sleeve and normally projects with an end part 64 into a bore 53A in the surrounding housing 53. A compression spring 61 serves to push auxiliary pin 60 into bore 53A. Thus in this normal position sleeve 51 is rotatably locked to housing 53. Release of this lock or blocking effect takes place by means of cam surfaces formed by edge portions of a recess 66 in the surface of plug 51. A radial stud 62 on auxiliary pin 60 co-operates with recess 66 for this prupose. Stud 62 projects through an elongated groove 55B in the intermediate sleeve so that it can enter into recess 66.

As shown more clearly in fig. 5 recess 66 is approximately heart-shaped, having a crest or top point 66C and edge portions 66A and 66B tapering outwards from this point and extending in this example at angles symmetrically in relation to the longitudinal axis. From the opposite side in relation to point 66C a tongue 66D projects in a direction towards top point 66C and has its end located at a distance from point 66C greater than the lateral dimension of stud 62. In the normal position (as appears in particular from fig. 6) this stud has a rest just in top point 66C, which in actual practice will be represented by a rounding between the tapered edges 66A and 66B. Between these tapered edges and the tongue 66D there is all the way a sufficient space for stud 62 to be displaced while guided by these tapered edges outwards and inwards in relation to top point 66C.

With such a cam-like recess 6 rotation of plug 51 in relation to sleeve 55 will result in retraction of auxiliary pin 60 from bore 53A against the influence of spring 61, whereby a sufficient mutual rotational angle leads to removal of the rotational blocking between housing 53 and sleeve 55. In this respect the effect will be quite analogous to what is obtained by the auxiliary pin 20 and the cut-away cam part IB on the plug in the embodiment of figs. 1 and 2. Because of its position, however, the

auxiliary pin 60 is less subject to various forms of tampering or attempts to break the lock.

An important detail regarding the recess 66 consists therein that the end of the projecting tongue 66D has an end surface which faces the stud 62 at a relatively small spacing therefrom, so that possible attempts of boring opposite the end 64 of auxiliary pin 60, will not allow the auxiliary pin to be pushed inwards, because the stud 62 in such case wil abutt the end of tongue 66D. In this connection it is remarked that auxiliary pin 60 may also be oriented in an opposite manner, i.e. with the end par 64 directed to the left in figs. 5 and 6, with corresponding inverting of the recess 66.

Finally this embodiment has advantages with respect to centering of the plug for retraction of the key .after use. Tapering edges 66A and 66B together with spring 61 will bring plug 51 to be centered by having stud 61 pressed towards top point 66C. A dual function is obtained thereby, namely this centering effect in addition to removal of the blocking between housing 53 and sleeve 55. Compared to the embodiment of figs. 1 and 2, where particular structural elements 25 - 28 serve for the centering, a simplification is then obtained here. The simplification also applies to the auxiliary pin itself, which in figs. 5 and 6 is made up by a single element. Moreover the latter embodiment has the advantage of reducing the total length of the lock arrangement.