CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosures of U.S. application Ser. No. 17/892,931 entitled A KEY BLANK, A CODED KEY AND A CYLINDER LOCK AND KEY SYSTEM WITH IMPROVED STOP ARRANGEMENT filed on Aug. 22, 2022 and U.S. application Ser. No. 17/892,938 entitled A KEY BLANK, A KEY AND A CYLINDER LOCK AND KEY COMBINATION, filed on Aug. 22, 2022 the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention concerns a key plug for a cylinder lock, including a cylindrical body with a cylindrical contour around a rotary axis, configured to enable a rotary motion of the key plug in a cylindrical bore in a housing of an associated cylinder lock. A longitudinal keyway extends in the cylindrical body along a vertical mid-plane MP passing through or adjacent to the rotary axis and being configured to accommodate a substantially flat key blade of an associated key for releasing the cylinder lock. A row of radially oriented central bores are located in a vertical central plane VP passing through the rotary axis and communicating with the longitudinal keyway. A row of central locking pins are movable in the central bores and are configured for locking the key plug against rotation relative to the housing unless the key blade of the associated key has been inserted into a longitudinal position in the keyway which enables a release of the cylinder lock by turning the key and the key plug in the cylindrical bore of the housing. A cross-sectional profile of the keyway, along a major longitudinal portion of the key plug, is confined within a rectangle having a height being at least 2.5 times greater than a width thereof. The cross-sectional profile includes a lower relatively wide part, having a maximum width being substantially the same as or slightly less than the width of the rectangle, the maximum width being 75% to 100% of the width of the rectangle, measured between a first lower side wall and a second lower side wall, and an upper relatively narrow part serving to enable an interaction between an inserted key blade and the movable central locking pins in the central bores, and possibly an interconnecting part, adjoining to the lower and upper parts of the keyway so as to extend therebetween along the vertical mid-plane.

The “vertical mid-plane” is intended to define a plane which is located between the lateral side walls of the keyway. Here, “vertical” refers to the orientation shown in the drawing figures, and “mid” is intended to define a location substantially centrally between the lateral sides of the rectangle without necessarily being located exactly in the middle between these lateral sides.

However, all parts of the keyway should be confined substantially within the rectangle and extend along or substantially in parallel with the “vertical mid-plane”, all the way from the bottom to the top.

It should also be pointed out that in this disclosure, the terms “upper,” “lower,” “vertical” and “horizontal” are used with reference to the illustrated embodiments and may just as well be reversed or changed to a different orientation of the key blade when being used in practical applications.

The scope of the invention also includes a cylinder lock, a cylinder lock and key combination, and a method to manufacture a key plug.

BACKGROUND OF THE INVENTION AND PRIOR ART

Such key plugs, cylinder locks and cylinder lock and key combinations have been developed gradually from a basic design created long ago, namely by Linus Yale Junior in the 1860s, and are still being improved by various measures in order to increase the security against unauthorized opening of the lock and facilitating a rational production of locks and keys in large numbers. A wide-spread overall structure of the key plug, and a substantially flat key blade of a corresponding key or key blank, includes generally a cross-sectional profile consisting of three parts, each having a specific task, viz. a lower relatively wide part, serving mainly to guide the key blade in the keyway of the cylinder lock, an interconnecting part, serving to make it more difficult to manipulate the cylinder lock, when there is no properly cut key inserted into the keyway, and an upper, relatively narrow part having an edge portion serving to position a row of central locking pins in the central bores into predetermined locations so as to release the lock.

A contemporary example of such a lock and key system is disclosed in the published European patent application EP 3,366,870 A1 (ASSA AB), where the improvement relates to a stop arrangement defining a selectable stop for the full insertion of the key blade into the keyway of the plug, where the key can be turned together with the key plug and release the cylinder lock. The keyway in the key plug of the associated lock has a corresponding number of longitudinal recesses and ribs, and inclined portions, so that the key blade of the associated key will fit slidingly with some play within the keyway. In the cross-sectional profile of the key blade and the corresponding keyway, in the part extending vertically between the lower and upper parts and thus forming an interconnecting part, there are several portions being inclined in alternating directions. The inclinational angles, relative to a central plane, are quite large, so that the adjacent portions will form relatively sharp bends therebetween. This is a type of key blade and keyway configuration which is frequently used today in cylinder lock and key systems.

Owing to the bends between the inclined portions of the profiled keyway, the security of the cylinder lock is enhanced, since it is relatively difficult to reach, from below, the upper part of the keyway, where the lower ends of the locking pins are accommodated when the key has been withdrawn. Thus, it is difficult to observe or find out how to move the locking pins so as to open the lock, and the zig-zag or bent configuration of the interconnecting part of the keyway will therefore deter lock-picking attempts from below, in particular via the lower relatively wide part of the keyway. Of course, the lower relatively wide keyway is a part of the lock which is relatively easy to reach, because of its relatively large width.

OBJECT OF THE INVENTION

An object of the present invention is to provide a key plug having a keyway with a relatively simple geometrical shape, which has no alternating directions of adjacent inclined portions and no sharp bends therebetween and which is still advantageous in respect of manufacture and use, rendering a good strength of the associated key blank structure, and a reliable and effective use when forming part of a lock and key combination or system.

A further object is to provide a structure of the key plug, which will further facilitate rapid and rational manufacturing of cylinder lock and key combinations in large numbers, in particular with a rational method that simplifies the manufacturing of key plugs of cylinder locks.

A still further object is to provide, in spite of a relatively simple geometrical shape, a structure of the key plug which will maintain a sufficiently high security against manipulation and unauthorized opening of cylinder locks having such key plugs.

SUMMARY OF THE INVENTION

According to the present invention, the above objects are met by providing a basic structure of the key plug as recited above in the section “FIELD OF THE INVENTION,” wherein the upper relatively narrow part of the keyway has a relatively small lateral width being no more than 33% of the maximum width of the lower relatively wide part of the keyway and extends obliquely upwards along a first direction pointing away from the lower side wall of the lower part and being inclined at a relatively small angle α, in the interval 3° to 12°, relative to the vertical mid-plane. The sideways or lateral location, within the rectangle, of the upper relatively narrow part of the keyway, including first and second upper side walls thereof, is such that an imaginary downward extension thereof, substantially in a second direction opposite to the first direction down to an outer cylindrical contour of the key plug, will fall onto the outer cylindrical contour at a same second side of the vertical mid-plane and inside the second lower side wall of the keyway.

With such a configuration of the key plug, including a relatively narrow, slightly inclined upper part of the keyway, the above objects are achieved.

Thus, the inclinational angle α of the upper part of the keyway, relative to the vertical mid-plane, is only 3° to 12°, which is a rather small angle. Nevertheless, this small angle is significant and effective, and will provide an increased security against lock-picking, in spite of the very simple structure of the keyway, as will be explained below. The inclinational angle α may be 5° to 10°, in particular 8° to 9°.

The “vertical mid-plane” is possibly displaced sideways, in relation to the vertical lower part of the keyway.

In an embodiment, the lower relatively wide part of the keyway includes, at a vertical level adjacent to an interconnecting part, a laterally offset region located substantially at a same lateral side of the vertical mid-plane as the second lower side wall of the keyway, wherein the interconnecting part of the keyway adjoins to the laterally offset region of the lower part and extends vertically upwards therefrom, with a central side wall located in the vicinity of the vertical mid-plane and being inclined in the first direction, away from the laterally offset region of the lower part, and with an outside side wall located above and adjoining, possibly via a transition, to the second lower side wall of the keyway, and the upper part of the keyway forms an upward extension of the interconnecting part, forms, at the first upper side wall, an upward extension of the central side wall of the interconnecting part, and also adjoins, at the opposite second upper side wall, to the outside wall of the interconnecting part, possibly via a transition.

This configuration of the keyway will increase the security against picking and manipulation, since there is only a limited access from below to the central bores accommodating the lower central locking pins.

More particularly, the interconnecting part of the keyway is configured so as to establish a free visual communication between the lower relatively wide part of the longitudinal keyway and the central bores only via a respective narrow opening passage, denoted NOP, being offset laterally sideways in relationship to the vertical mid-plane, predominantly on the second side of the vertical mid-plane, whereas the first upper side wall of the upper part is located predominantly on the opposite first side of the vertical mid-plane, and the narrow opening passage NOP, as seen in a direction in parallel to the vertical mid-plane MP, has a lateral width which is less than 25% of the maximum width of the lower relatively wide part.

The narrow opening passage NOP will make it rather difficult to reach the central bores and the lower central locking pins when there is no key present in the keyway.

The relatively small lateral width of the upper part of the keyway may be substantially uniform along the vertical extension of the upper part, possibly with a tapering uppermost portion thereof. As will be apparent below, this will facilitate the manufacturing of the keyway by using a rotating cutter disc unit.

Advantageously, at least a part of the first and second upper side walls of the upper part of the keyway are located on a first side and on a second side, respectively, of the vertical mid-plane, and a central side wall of the interconnecting part of the keyway may cross the vertical mid-plane. So, the upper part of the keyway will be located centrally in relation to the vertical mid-plane.

With regard to the central bores and the lower locking pins, a lower end portion of a respective central bore may be tapered, possibly conically or as a chisel, and may accommodate an associated central locking pin with a correspondingly tapered lower end portion, which has a lowermost central end surface at its apex. This lowermost central end surface, preferably having a rounded shape, will be at least partly concealed when being observed or manipulated from underneath, when there is no associated key inserted into the keyway and the associated central locking pin is being held in its lowermost position.

In order to improve the security, the total height of the interconnecting part and the upper part may be in the interval 50% to 85% of a total height of the keyway. In this way, there will be a relatively long distance from the lower part of the keyway up to the lower locking pins being accommodated in the central bores in the key plug.

In an embodiment, the lower part of the keyway has an upper first transverse wall located substantially on the same lateral side of the vertical mid-plane as the first upper side wall of the upper part of the keyway, the transverse wall forming a corner with an adjoining central side wall of the interconnecting part, the corner being located in the vicinity of the vertical mid-plane, and the first transverse wall forming at least a part of a first step-like transition between the lower part and the interconnecting part.

Furthermore, the first transverse wall may extend laterally all the way from the first lower side wall of the lower part to the corner, so as to form the first step-like transition. Alternatively, the first step-like transition may comprise an upward extension, configured to accommodate a ridge of an associated key blade, the upward extension having an outside wall portion adjoining to the first lower side wall of the lower part of the keyway, a top wall portion, and an inside wall portion adjoining to the first transverse wall. The first transverse wall will thus form only a part of the first step-like transition, and there is formed a centrally located downwardly directed tongue being defined by the inside wall portion, the first transverse wall with the corner, and the central side wall of the interconnecting part.

Moreover, the second upper side wall of the upper part of the keyway may adjoin, as a substantially straight extension through the interconnecting part to the second lower side wall of the lower part, or there may be a second transition on the other side of the vertical mid-plane, where the second upper side wall of the upper part adjoins to the outside surface of the interconnecting part.

The key plug may comprise a front end portion extending along less than half of a total length of the key plug, and an adjoining rear end portion along more than half of the total length. The front end portion accommodates a side locking mechanism with side locking tumblers reaching into the longitudinal keyway, whereas the rear end portion may accommodate one or more additional lock components at a lateral side of the longitudinal keyway, a structure which is previously known per se from the U.S. Pat. No. 10,337,210 B2 (Widén) relating to an interchangeable cylinder lock core for a cylinder lock unit, and the corresponding continuation-in-part U.S. Pat. No. 10,570,643 B2 (Widén) relating to a cylinder lock core for a cylinder lock unit.

According to these patent specifications, there is at least one side code pattern confined entirely to a front region of the rotatable key plug of the lock, and the side locking tumblers of each side locking mechanism are movable independently of each other with at least three different code positions for each coded side locking tumbler and a plurality of different code combinations for each side locking mechanism.

However, in the present invention, the side code locking mechanism of the cylinder lock may extend either along only a part of the entire length of the key plug or, alternatively, it may extend along substantially the entire length thereof, from the front end widened portion to the rear end. Thus, a person having ordinary skill in the art may very well combine the teachings of the above two U.S. patents, without necessarily having a coded side locking mechanism being confined only to a front region of the key plug, and the present disclosure when designing a lock and key system, within the scope of the appended claims of the present invention. Thus, for example, the key plug may comprise, on one or both lateral sides of the keyway, in a rear end portion of the key plug, a longitudinal prong hole for accommodating a longitudinal prong configured to transfer a torque from the key plug to a locking member in an associated lock unit. Alternatively, there may be located some other lock component in the key plug on a lateral side of the keyway.

As indicated above, within the scope of the present invention, the key plug may be combined with an associated housing so as to form a cylinder lock.

In a cylinder lock according to the invention, there being possibly one or more side locking tumblers on one or both lateral sides of the keyway, each side locking tumbler may be movable in an associated cavity and may have a transverse projecting finger reaching into the keyway of the key plug, the side locking tumbler cooperating with the housing, possibly via a side bar, when a correctly cut key has been inserted into a longitudinal position in the keyway which enables a release of the cylinder lock by turning the key and the key plug in the cylindrical bore of the housing.

Moreover, within the scope of the appended claims, the cylinder lock may be combined with an associated key having a substantially flat key blade, so as to form a cylinder lock and key combination, the substantially flat key blade having at least one key code pattern, namely a central key code pattern adjacent to an upper edge surface of an upper part of the substantially flat key blade, with a longitudinal row of coded cuts, configured to interact with the movable central locking pins in the key plug of the cylinder lock, and possibly also at least one side code pattern in a respective side surface portion of the key blade, configured to interact with side locking tumblers of a side code mechanism of the cylinder lock.

The present invention also concerns a method to manufacture a key plug from a key plug blank having a cylindrical body with a cylindrical outer contour around a rotary axis, a longitudinal keyway extending in the cylindrical body along a vertical mid-plane MP passing through or adjacent to the rotary axis, a row of radially oriented central bores located in the cylindrical body in a vertical central plane VP passing through the rotary axis and communicating with the longitudinal keyway, a cross-sectional profile of the keyway consisting of at least two parts, viz. a lower relatively wide part and an upper relatively narrow part, and possibly an interconnecting part, adjoining to the lower and upper parts so as to extend therebetween along the vertical mid-plane. The method comprises machining the longitudinal keyway into the key plug blank, before or after drilling the radially oriented central bores with axes located in the vertical central plane VP, and wherein, in one major step, at least the upper part of the keyway in the key plug blank is machined by means of a first cutter disc unit including a rotating first cutter disc, which is held in a plane which is slightly inclined at a selected angle α, in the interval 3° to 12°, relative to the vertical mid-plane of the key plug, the vertical mid-plane MP of the keyway being possibly displaced sideways in relation to the vertical central plane VP of the central bores, a distance no more than 15% of a maximum lateral width of the lower relatively wide part, and the rotating first cutter disc is moved longitudinally along the blank with a cutting depth including the lower part, the possible interconnecting part and the upper part of the keyway.

In this way, the keyway of the key plug may be manufactured in a rapid and simple manner, possibly without having to use broaching tools, as is normally done when producing key plugs for mechanical cylinder locks. The costs will be reduced, and the method according to invention will be rational, rapid and cost-effective. Still, the security of cylinder locks with such key plugs will be sufficiently high, as will be described in detail below.

The rotating first cutter disc unit may include a driving shaft, on which the first cutter disc is mounted, the driving shaft being maintained, during the longitudinal movement of the rotating cutter disc, at the selected, relatively small angle α relative to an axis which is perpendicular to the vertical mid-plane MP.

Possibly, further machining steps may be carried out, before or after the one major step, in order to further widen or to modify the keyway as desired in the lower part, the possible interconnecting part and/or the upper part of the keyway.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

