Patent Description:
Business establishments, or even homes, often desire to be able to change one or more locks so that the key normally used for opening the lock is changed, and an old key which has previously been operative to open the lock will no longer work. Moreover, preferred locks are of the type adapted to having the tumblers forming portions of the lock mechanism changed in their operative status relative to each other without the necessity of disassembling the lock, or removing it from the door in which it is located.

In various business establishments such as motels, hotels, and chains of department stores, a great many locks are frequently utilized. In most cases, the business desires a master key which will unlock any one of these locks in the event persons in possession of the regular keys for unlocking the locks are unavailable or to allow one master key to access various locks which require separate change keys (also called "patron keys"). With the provision of one or more master keys, which are maintained in the custody of a few selected personnel, the versatility of this type of lock in a multi-lock situation is increased. Situations arise, however, from time to time, in which a custodian of a master key leaves the employ of the organization where the locks are utilized, and, through inadvertence or intent, takes one of the master keys which will unlock any of the locks in use of the type described, and will continue to unlock such locks even though the dimensions of the tumblers in the locks may be changed to accommodate new individual change keys. The security of the establishment is obviously compromised by the loss of master keys in this manner, and the usefulness of the lock is enhanced if it can be changed so that master keys, which would previously effectively unlock or open the lock, can no longer be used, and new master keys are required for this purpose. The usefulness of the lock is further enhanced, if it can be changed to accommodate a new master key without the necessity for removing the lock from the door or disassembling the lock.

Previously proposed locks having provisions for changing the patron key combination and the master key combination have not proved entirely satisfactory as they employ a large number of intricate parts and are extremely complex in construction and operation. Certain of these locks have relatively large physical dimensions and are therefore limited to specific applications. Also, the number of permutations to which the combination may be changed has been severely limited. In addition, certain of these previously proposed locks require special keys, which are significantly different from conventional keys.

<CIT> discloses a key operated lock. <CIT> discloses a changeable lock assembly.

In accordance with one series of embodiments of the current disclosure, there is provided a key-operated lock comprising a housing, a core (generally, known in the industry as a plug) and a set of pin stacks. The housing has a circularly cross-sectioned bore therein defined by a bore wall. The bore has an axial direction. The housing has a set of driver chambers aligned along the axial direction with each driver chamber extending radially towards the bore. Further, the housing has a set of inactive master-pin chambers aligned along the axial direction with each inactive master-pin chamber extending radially towards the bore. The set of inactive master-pin chambers are spaced circumferentially around the bore from the set of driver chambers and each inactive master-pin chamber aligns circumferentially with a respective driver chamber.

The core is rotatably mounted in the bore and has a main key slot and a change tool slot formed therein. Both the main key slot and change tool slot extend substantially parallel to the axial direction. The core has an outer cylindrical surface which meets the bore wall at a shear line.

Each pin stack comprises pin stack elements, which include a driver and a tumbler. The driver is movably mounted in one of the driver chambers for radial movement relative to the bore in the housing, and for movement partially into the bore in the housing. The tumbler assembly is movably mounted in the core for radial movement relative to the bore in the body and moveable to a position projecting from the core. In a key-pull position of the core, the tumbler assembly is radially aligned with the driver. Further, the tumbler assemblies including a plurality of releasably engaged parts movable relative to each other upon disengagement to change a dimension of the tumbler assemblies. The releasably engaged parts are disengaged by insertion of a change tool into the change tool slot when the core is in a top-master-rekey position.

Additionally, for at least one of the pin stacks, the pin stack elements further comprise one or more master pins. Each master pin is moveable between a position within the core above the respective tumbler assembly and a position in the inactive master-pin chamber when the core is in a basic rekey position (also called patron rekey position) in which the tumbler assembly is radially aligned with the set of inactive master-pin chambers.

Generally, the pin stack elements meet at shear points such that, when all the pin stacks have shear points coincident with the shear line, the core is free to rotate in the bore at least among the first position, the second position and the third position. When at least one of the pin stacks does not have a shear point coincident with the shear line, the core is not free to rotate.

In most embodiments, when a top-master key is inserted into the main key slot, all the shear points associated with all the tumbler assemblies are coincident with the shear line. The lock is configured such that the top-master key can be changed by changing the dimension of the tumbler assemblies when the lock is in the top-master rekey position.

In many embodiments, when a current patron key is inserted into the main key slot, at least one shear point associated with one of the master pins and either another master pin or the driver is coincident with the shear line.

Further, the lock can be configured such that the patron key can be changed by moving at least one master pin between the position within the core above the respective tumbler assembly and the position in the inactive master-pin chamber.

In another set of embodiments, there is a key-operated lock comprising a housing, a core rotatably mounted in the housing; a plurality of master pins in a first configuration to allow a first patron key to open the lock; and a plurality of reconfigurable tumbler assemblies in a first arrangement to allow a first master key to open the lock.

The housing, the core, the plurality of master pins and the plurality of pin stacks are configured to have:.

In some of these embodiments, each reconfigurable tumbler assembly comprises a plurality of releasably engaged parts movable relative to each other upon disengagement to change a dimension of the tumbler assemblies. The releasably engaged parts are disengaged by insertion of the change tool into a change tool slot in the core when the lock is in the top-master-rekey position.

Each reconfigurable tumbler assembly can be a part of a pin stack such that there are a plurality of pin stacks in the lock. At least one of the pin stacks can include at least one master pin. The master pin is moveable in and out of the pin stack in the basic rekey position. Additionally, the housing can have a set of inactive master-pin chambers which retains master pins which are not in one of the pin stacks.

In some of the embodiments, the key-operated lock is configured to have a grandmaster key, a master key and a patron key and wherein the master key and patron key are slave keys to the grandmaster key.

Other embodiments provide for a method of rekeying a key-operated lock comprising:.

In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the invention. In the following description unless the context would indicate otherwise, the terms "inward", "outward", "lower" and "upper" are directions toward and away from, respectively, the geometric axis of a referenced object. Accordingly, "inward" means towards the center or geometric axis, and "lower" refers to a first point radially inward from a second point. Likewise, "outward" means away from the center or geometric axis, and "upper" refers to a first point radially outward from a second point. Where components of relatively well-known designs are employed, their structure and operation will not be described in detail.

As used herein, the following terms will have the following meanings.

"Patron key" as used herein refers generally to a key that operates a specific lock and not other locks. When such a lock can be rekeyed to use a different patron key, the patron key is typically referred to as a "change key". In this disclosure, "change keys" will often be referred to as "patron keys".

"Master key" refers to a key that can operate on several keyed different locks. These locks are configured to operate with two, or more, different keys: one specific to each lock (the "patron key" or "change key") which cannot operate any of the other locks in the set, and the master key, which operates all the locks in the set. In some embodiments, there can be a "grandmaster key" or "top-master key" that can operate all the locks in multiple sets of locks. In such embodiments, there typically are master keys and individual patron keys. The "master keys" are keys that can open all the locks of one of the set of locks but not locks in other sets. The "individual patron keys" are keys that can only open a specific lock in one of the sets of locks.

"Slave key" refers to a particular patron key that will only operate a lock if its associated master key also operates the lock. If the cylinder is rekeyed to a new master key, the previous master and previous patron key will no longer operate the cylinder.

"Level <NUM> system" means a lock system (a group of two or more locks) with patron keys and a master key. For example, a level <NUM> system for a hotel is shown in <FIG>.

"Level <NUM> system" means a lock system with a top-master key (or grandmaster key), master keys and individual patron keys. For example, a level <NUM> system for a hotel is shown in <FIG>.

"Key-pull position" means the position where the sub-holes (containing the tumbler pins) on the core align with the active driver chambers on the housing. This is the natural locked position of the cylinder.

"Shear line" is where the outside diameter of the core and the inside diameter of the housing meet. When an interface (shear points) of elements for each pin stack coincides with the shear line, the core is able to be rotated to unlock the lock.

The above definitions are to facilitate understanding, the meaning of the above terms, components used in the definition, and other components can be further understood by reference to the below description of embodiments.

Referring initially to <FIG> of the drawings, the key operated lock <NUM> of the invention includes a housing <NUM> which is illustrated as being generally cylindrical in form and is sometimes referred to in the trade as the "cylinder" or "shell". Housing <NUM> has a cylindrical bore <NUM> defined by circumferential-extending wall <NUM> (see <FIG>) extending therethrough. An elongated core <NUM>, which is preferably generally cylindrical in configuration, is rotatably mounted in cylindrical bore <NUM> in housing <NUM>.

As can be seen most clearly in <FIG>, housing <NUM> can include a circumferential flange <NUM> which extends around one end of housing <NUM>. The purpose of the flange <NUM> is to abut the face of a door or other member in which the lock is to be installed. Housing <NUM> can have an external thread <NUM> which is provided to secure the lock in the door or other member where the lock is to be used.

Housing <NUM> has a set of apertures <NUM> which extend radially through wall <NUM> of housing <NUM> to cylindrical bore <NUM>. Typically, the set of apertures will comprise a plurality of apertures <NUM>, which are often referred to as "driver chambers". An elongated, dove-tailed groove or slot <NUM> extends from one end of housing <NUM> to flange <NUM> and is provided to accommodate a cover plate <NUM> which, when placed in slot <NUM>, covers apertures <NUM> in the body.

An active driver <NUM> is slidingly positioned in each of apertures <NUM> in housing <NUM>. Each active driver <NUM> is constantly urged toward the core <NUM> by a driver spring <NUM>, which has one of its ends disposed in a recess or bore in the respective driver <NUM> and its opposite end abutting the elongated cover plate <NUM>, as can best be seen by the sectional view of a driver in <FIG>.

Housing <NUM> has a second set of apertures <NUM>, which extend radially through wall <NUM> of housing <NUM> to cylindrical bore <NUM>. Typically, the set of apertures will comprise a plurality of apertures <NUM>, which will also be referred to as "inactive master-pin chambers" (see <FIG>). An elongated, dove-tailed groove or slot <NUM> extends from one end of housing <NUM> to flange <NUM> and is provided to accommodate a cover plate <NUM> which, when placed in slot <NUM>, covers apertures <NUM> in the body.

A master-pin driver <NUM> is slidingly positioned in each of apertures <NUM> in housing <NUM>. Each master-pin driver <NUM> is constantly urged toward the core <NUM> by a driver spring <NUM>, which has one of its ends disposed in a recess or bore in the respective driver <NUM> and its opposite end abutting the elongated cover plate <NUM>.

Housing <NUM> has a shallow counterbore <NUM> in the end thereof which carries flange <NUM>, and this counterbore intersects the cylindrical bore <NUM> at a shoulder <NUM>. Core <NUM> is provided at one of its ends with an annular flange <NUM> dimensioned to rotatably fit within counterbore <NUM> and abut against shoulder <NUM> when core <NUM> is inserted in cylindrical bore <NUM> in housing <NUM>. At the end of core <NUM> opposite the flange <NUM>, the core has secured thereto in any suitable manner (such as by screws or the like) a lock cam <NUM> which serves the dual purposes of preventing core <NUM> from moving toward the forward end of the lock within housing <NUM>, and to actuate a lock bolt (not shown) in a manner well understood in the art.

A key slot <NUM> extends longitudinally through core <NUM> and is suitably configured to accept a key for operating the lock. The key used in the key slot <NUM> may be an individual patron key for everyday usage, a master key, or a top-master (grandmaster) key. <FIG> illustrates top-master key <NUM> in key slot <NUM>.

A plurality of apertures <NUM> extend radially in core <NUM> and have one end in communication with the key slot <NUM>. Apertures <NUM> open at the outer periphery of core <NUM> and are positioned to register with apertures <NUM> in housing <NUM> when the core <NUM> is in the key-pull position in housing <NUM> as shown in <FIG>. The apertures <NUM>, in the illustrated embodiment of the invention, are each generally cylindrical in configuration but connect with semicircular slots <NUM> which are transversally intersected by slot <NUM> that runs longitudinally along core <NUM>, best seen from <FIG>. Slots <NUM> and <NUM> are dimensioned to receive sidebar <NUM>, and apertures <NUM> are each dimensioned to receive a generally cylindrical tumbler assembly <NUM>, and such that tumbler assembly <NUM> and sidebar <NUM> can interact as described below.

Tumbler assembly <NUM> operates in place of more typical static tumbler pins. As best seen from <FIG> and <FIG>, core <NUM> has a plurality of tumbler assemblies <NUM>. Each of the tumbler assemblies <NUM> includes a hollow cylindrical housing or retainer sleeve <NUM> which is closed at one end <NUM> thereof and slidingly disposed within one of the cylindrical apertures <NUM> in core <NUM>. Slidingly disposed within the interior of the sleeve <NUM> is an extensible member or plunger <NUM> which has an upper portion <NUM> carrying a plurality of spaced circumferential ribs or flanges <NUM>, and a lower portion <NUM> having a tapered face <NUM>, which, when installed in lock <NUM>, extends into key slot <NUM> to a position for contacting a key inserted in the slot as depicted in <FIG> and hereinafter described in greater detail.

A spring member <NUM> is provided between the closed end <NUM> of sleeve <NUM> and the upper portion <NUM> of the plunger <NUM> to constantly urge the plunger away from closed end <NUM> of sleeve <NUM> and toward the main key slot <NUM>.

A hollow projection <NUM> extends outwardly from one side of sleeve <NUM> and is adapted to receive a portion of a retainer pin <NUM>. Retainer pin <NUM> is of T-shaped configuration and includes a projecting flange portion <NUM>, a barrel <NUM>, and a tip <NUM> formed on the end of the barrel which is opposite the flange portion <NUM> (see <FIG>). Barrel <NUM> of retainer pin <NUM> projects through a bore formed in hollow projection <NUM> which extends outwardly from one side of sleeve <NUM>. It will further be noted, that the tip <NUM> of retainer pin <NUM> projects between the spaced, circumferential ribs <NUM> of the upper portion <NUM> of the extensible member <NUM>. Retainer pin <NUM> thus functions to engage sleeve <NUM> of the tumbler assembly <NUM> with the extensible member <NUM>.

As discussed above, each of the generally cylindrical apertures <NUM> formed in core <NUM> opens at one of its sides into a substantially semicircular slot <NUM> cut radially inwardly into the side of core <NUM> and of the general configuration shown in <FIG>. There is one of the slots <NUM> cut in the body of core <NUM> in correspondence to each one of the apertures <NUM>, with the series of longitudinally spaced slots <NUM> in core <NUM> registering with the series of radially extending, longitudinally spaced apertures <NUM> formed therein. The series of slots <NUM> cut in one side of core <NUM> are intersected by a longitudinally extending slot <NUM> cut along a major portion of the length of the core and extending from the outer surface of the core in a radially inward direction. At its base, longitudinally extending slot <NUM> intersects a relatively small, axially extending change tool slot <NUM> which extends through core <NUM> in a direction parallel to slot <NUM>. This relationship is perhaps best illustrated in <FIG> of the drawings where a change tool <NUM> is depicted in position in the change tool slot <NUM>, and the upper portion of the longitudinally extending slot <NUM> is perceptible in dashed lines.

Sidebar <NUM> comprises a series of cam plates <NUM> which work in a cooperating relationship with each of the tumbler assemblies <NUM>. The cam plate <NUM> has a flat surface <NUM> which bears against the flange <NUM> of the retainer pin <NUM> and has a rounded cam surface <NUM> on the opposite side of the cam plate from the flat surface. One of the cam plates <NUM> is provided for contact with each of the retainer pins <NUM>, and each cam plate <NUM> is elongated and relatively thin in configuration as can be seen in referring to these elements in <FIG> and <FIG>.

Each of the cam plates <NUM> has locating pins <NUM> projecting from the opposite sides thereof. The cam plates <NUM> are positioned in the several semicircular slots <NUM> with locating pins <NUM> extending into the longitudinal slot <NUM> in core <NUM> in the manner best illustrated in <FIG>. The cam surfaces <NUM> of the several cam plates <NUM>, in most positions of core <NUM> within housing <NUM>, bears against cylindrical wall <NUM> of bore <NUM> in the housing. In one position (the "top-master-rekey position") to which core <NUM> may be rotated, however, cam surfaces <NUM> of the several cam plates <NUM> are aligned with the driver chambers <NUM> in housing <NUM> which receive the active drivers <NUM>. This position of the cam plates is depicted in <FIG>. It will be noted that when core <NUM> is rotated to the position shown in <FIG>, cam plates <NUM> may be moved radially outwardly, as may the retainer pins <NUM> with which these plates are in contact. As will be subsequently explained, this status of the lock permits change tool <NUM> to be utilized for biasing retainer pins <NUM> to a disengaging status so that the extensible members <NUM> and retainer sleeve <NUM> may undergo movement relatively to each other.

Lock <NUM> further utilizes master pins <NUM>. Each master pin <NUM> is a small pin that can sit between closed end <NUM> of one of the tumbler assemblies <NUM> and the bottom of the corresponding active driver <NUM>. When a master pin is between closed end <NUM> and the active driver <NUM>, it creates additional interfaces or shear points, which can align with the shear line of lock <NUM>. Thus, the master pins allow for multiple keys to turn core <NUM>. Each tumbler assembly <NUM> and its corresponding active driver <NUM> comprise a basic pin stack. In the basic pin stack, the pin stack elements (tumbler assembly <NUM> and active driver <NUM>) provide a shear point at the interface of closed end <NUM> with active driver <NUM>. If no master pins are present in any of the pin stacks, then only the top-master key can turn core <NUM> and thus unlock the lock. In most embodiments of the invention, at least a portion of the pin stacks will contain one or more master pins. In these pin stacks, there will be additional shear points based on the interface of the master pin interfaces with the bottom of active driver <NUM>, closed end <NUM> of tumbler assembly <NUM>, or with another master pin. For example, if one master pin <NUM> is present in a pin stack then there will be two shear points, one at the interface of the master pin with closed end <NUM> of tumbler assembly <NUM> and the other at the interface of the master pin with the bottom of active driver <NUM>. The first or lower of these shear points allows the top-master key to turn core <NUM>; the latter or upper of these shear points allows a patron key to turn core <NUM>. If two master pins <NUM> are present in a pin stack, then there will be three shear points, one at the interface of the lower master pin with closed end <NUM> of tumbler assembly <NUM>, a second at the interface of upper master pin and lower master pin, and the third at the interface of the upper master pin with the bottom of active driver <NUM>. The first or lower of these shear points allows the top-master key to turn core <NUM>; the second (middle) shear point and third (upper) shear point can allow for two different keys to turn core <NUM>. However, generally only the upper shear point will be used for the key progression as discussed in the Key Progression section.

As shown in <FIG>, in one embodiment the master pins are disc shaped pins having beveled or angled edges to facilitate movement rotation of core <NUM> when the interface is aligned at the shear line. The edges can have an angle D from about <NUM>° to about <NUM>°, more typically from about <NUM>° to about <NUM>°. As illustrated in <FIG>, the master pins can have different thicknesses to provide for better security and more combinations for key configurations. In one embodiment, the master pins can have from <NUM> to <NUM> different thicknesses. As illustrated, the master pins have <NUM> different thicknesses.

When not in use, master pins <NUM> are positioned in apertures or inactive master-pin chambers <NUM>. As will be appreciated by one skilled in the art based on this disclosure, movement of the master pins <NUM> between the pin stacks and inactive master-pin chambers <NUM> allows rekeying of lock <NUM> to be operated by different patron keys, some of which can be master keys to others which are individual patron keys. A master pin <NUM> can be moved between a pin stack and a corresponding inactive master-pin chamber <NUM> by a process further described below.

The embodiments of the current lock structure use a single type of key and a change tool. The patron keys and top-master key are of the same type or same configuration and differ only in the milled surface. The top-master key is milled to unlock all the locks of a set of locks, while patron keys are milled to unlock only a few specific individual locks of the set or one specific individual lock in the set of locks. If the patron key is milled to unlock a few specific locks of the set of locks it is a master key coming under or slave to the top-master key. If the patron key is milled to unlock only a specific individual lock, it is an individual patron key coming under the master key and the top-master key and a slave to both. As described below, the patron keys (including a master key in a level <NUM> system) for any specific individual lock can be changed without utilizing any special tool other than the current patron key and a new patron key. Additionally as described below, the top-master key can be changed for any specific individual lock but requires the current patron key, current top-master key and the change tool.

As may be understood by one skilled in the art based on the above disclosure and will be understood by the below disclosure, the current lock allows rekeying to the top-master key (grandmaster key) by manipulation of the tumbler assemblies and basic rekeying of the patron keys and master keys (in a level <NUM> system) is by manipulation of the master pins.

The general operation of key lock structures, which include cooperating drivers and tumbler pins aligning at a shear line, is generally well understood in the art. Locks of this type may be opened at such time as the drivers and the tumbler pins cooperate to permit a cylindrical core <NUM> to be rotated within a housing. Such rotation of the core causes a lock cam to be moved against a lock bolt so as to release the door from its surrounding frame and permit the door to be opened.

The nomenclature "change key lock" is used herein to refer to locks of the type with the capability to be changed in their internal mechanism so that a key which has previously been effective for unlocking the lock will no longer perform this function, but rather, a new key must be used for this purpose. In the past, systems for change key locks typically could not accommodate both level <NUM> systems and level <NUM> systems and have easy operation of the rekeying of the lock. Often such change key locks only provided for level <NUM> systems or had complicated and hard to implement rekeying operations. Additionally, many such change key locks relied on master keys or top-master keys having unique configurations from the patron keys. Thus, they had to incorporate multiple key holes or rely on complicated key holes that could accommodate two different key configurations.

The embodiments of the present lock <NUM> provide for the use of a top-master key having the same configuration as the patron key but a different milled surface. Thus, the top-master key and patron key use the same configuration of key hole. Additionally, the embodiments provide for an easy system of rekeying the lock to use different patron keys and an easy system for rekeying the lock to use a different top-master key.

Rekeying of the lock to use different patron keys but to retain the same top-master key will now be described with reference to <FIG>, wherein the views are from the front of housing <NUM>. <FIG> illustrate the use of the initial top-master key and initial patron key, those prior to rekeying. As will be appreciated from <FIG>, when the initial top-master key <NUM> is inserted into key slot <NUM>, all the shear points <NUM> associated with end <NUM> of all the tumbler assemblies <NUM> are coincident with the shear line <NUM>. As can be seen, master pins <NUM> are above the shear line and are within driver chamber <NUM>. Accordingly, when core <NUM> is turned, the master pins will remain within driver chamber <NUM>. As illustrated in <FIG>, when initial individual patron key <NUM> is inserted into key slot <NUM>, then at least one of the pin stacks will have a shear point <NUM> coincident with the shear line <NUM> such that the shear point <NUM> will be between a master pin and the active driver. As illustrated, the shear point <NUM> is between a master pin 104a and active driver <NUM>. As can be seen, master pin 104a is below the shear line and is within aperture <NUM> of core <NUM>. Accordingly, when core <NUM> is turned, master pin 104a will remain in aperture <NUM> and move with core <NUM>.

In order to accomplish rekeying for a new individual patron key, the initial individual patron key <NUM> is inserted into key slot <NUM> in the key-pull position, as shown in <FIG>. Core <NUM> is then turned to a basic rekey position, shown in <FIG> as being at about <NUM>° from the key-pull position, but can be any suitable position. In this position, apertures <NUM> and tumbler assemblies <NUM> are aligned with inactive master-pin chambers <NUM>. Driver spring <NUM> keeps master pins <NUM> in aperture <NUM>. The current individual patron key is withdrawn and a new individual patron key <NUM> is inserted, as shown in <FIG>. New individual patron key <NUM> has a different milled surface sufficient to partially compress driver spring <NUM>; thus, its insertion causes at least one master pin <NUM> to move between an inactive master-pin chamber <NUM> and the corresponding aperture <NUM>. As is illustrated, upper master pin 104a is moved into inactive master-pin chamber <NUM> and lower master pin 104b remains in aperture <NUM>. Subsequently, when core <NUM> is turned back to the key-pull position as shown in <FIG>, only one master pin 104b is part of the lock stack assembly and its interface with active driver <NUM> is the shear point <NUM> used by new patron key <NUM>.

The lock is now rekeyed for the new individual patron key <NUM>, which may be withdrawn from key slot <NUM>. For example, as shown in <FIG>, there are two master pins 104a and 104b associated with the illustrated pin stack for initial patron key <NUM>. After rekeying, there is one master pin 104b associated with the illustrated pin stack for new patron key <NUM>, as shown in <FIG>. After rekeying, the initial top-master key <NUM> can be inserted into key slot <NUM> and the shear points <NUM> associated with end <NUM> of all the tumbler assemblies <NUM> are still coincident with the shear line <NUM>, as shown in <FIG>. As can be seen, master pin 104b is above the shear line and is within driver chamber <NUM>. Accordingly, when core <NUM> is turned, master pin 104b will remain within driver chamber <NUM>. As illustrated in <FIG>, when the new patron key <NUM> is inserted in key slot <NUM>, then shear point <NUM> between active driver <NUM> and master pin 104b coincides with the shear line <NUM>. However, as shown in <FIG>, when initial individual patron key <NUM> is inserted into key slot <NUM>, the illustrated pin stack has no shear point coinciding with shear line <NUM>. Accordingly, initial top-master key <NUM> and new patron key <NUM> will operate the lock after rekeying but initial patron key <NUM> will not.

Accordingly, in changing the individual patron key, the master pins <NUM> in use in the pin stacks are changed so that these pin stacks will no longer cooperate with the milled surface of individual patron key <NUM> (previously operative to unlock the lock) in such a way that unlocking can be accomplished. Rather, the change in master pins results in the pin stacks accommodating a new and different individual patron key <NUM>, having a different milled surface which is correlated to the particular pin stack configuration dictated by the master pins <NUM> present in the pin stack after the change is effected. The above description is only for illustrative purposes, in actual practice master pins can be moved from more than one of the pin stacks, and master pins may be either added to or removed from a pin stack during rekeying. Additionally, for any particular pin stack zero, one, two or more master pins may be moved between any particular pin stack and its associated inactive master-pin chamber. However, for rekeying at the patron key level, at least one pin stack will have at least one master pin added or removed during rekeying. Also, while described for individual patron keys, it will be apparent that the same procedure can be carried out for any patron key whether an individual patron key or a level <NUM> master key within a level <NUM> system.

Rekeying of the lock to use a different top-master key and a different patron key will now be described with reference to <FIG>, wherein the views are from the front of housing <NUM> (the end with lock cam <NUM>). <FIG> illustrate the use of the initial top-master key and initial patron key, those prior to rekeying. As will be appreciated, <FIG> are substantially the same as <FIG>. From the discussion above, one skilled in the art will appreciate that the overall dimensions of the tumbler assemblies are fixed by the particular interlocking position of the tip <NUM> of the retainer pins <NUM> with the ribs <NUM> of the plungers <NUM>. Thus, upon insertion of the initial top-master key <NUM>, which is to be rendered inoperative, tumbler assemblies <NUM> are moved such that the closed upper ends <NUM> of the sleeves <NUM> are positioned in alignment along a meeting line in contact with the active drivers <NUM>. This meeting line coincides with shear line <NUM> between the outer periphery of core <NUM> and wall <NUM> defining the bore through housing <NUM>. With the active drivers <NUM> and tumbler assemblies <NUM> in this position relative to each other, core <NUM> can then rotate within cylindrical bore <NUM> in housing <NUM>.

In order to accomplish rekeying for the top-master key and patron key, the current individual patron key <NUM> is inserted into key slot <NUM>, as shown in <FIG>. Patron key <NUM> is the current lowest or basic individual patron key; thus, for any pin stack containing master pins, the shear point which aligns with shear line <NUM> for patron key <NUM> is shear point <NUM> between the upper master pin 104b and active driver <NUM>. Core <NUM> is then turned to the basic rekey position. As core <NUM> is turned, it carries any master pins currently in use within apertures <NUM>. The initial individual patron key <NUM> is withdrawn and the initial top-master key <NUM> is inserted, as shown in <FIG>. Initial top-master key <NUM> has a milled surface which, in corporation with the current dimensions of tumbler assembly <NUM>, pushes master pins <NUM> into inactive master-pin chamber <NUM>.

Core <NUM> is then turned using the initial top-master key <NUM> to a top-master-rekey position, shown in <FIG> as being about <NUM>° from the key-pull position, but it can be at any suitable position. When core <NUM> is in this position with initial top-master key <NUM> located therein, the cam plates <NUM> are positioned in alignment with driver apertures <NUM>. Thus, cam surfaces <NUM> of cam plates <NUM> bear against the inner ends of active drivers <NUM> in driver apertures <NUM>, and active drivers <NUM> may thus be biased outwardly in their respective apertures <NUM> against the force resiliently exerted by the springs <NUM>.

With the lock in the status described, a change tool <NUM>, of the type shown in <FIG>, is inserted in the change tool slot <NUM> and then comes to occupy the position with respect to the retainer pins <NUM> and cam plates <NUM> which is illustrated in <FIG> of the drawings. The change tool <NUM>, when inserted in this manner, effectively biases the several retainer pins <NUM> outwardly with respect to the hollow projections <NUM>. This movement of the retainer pins <NUM> is possible because the cam plates <NUM> are, at this time, free to move radially outwardly against the active drivers <NUM>, which can move outwardly in their respective driver chambers <NUM>. There is thus effected a disengagement of tips <NUM> of the several retainer pins <NUM> from plungers <NUM>. The plungers <NUM> thus become free to move relative to retaining sleeves <NUM>. The retaining sleeves <NUM> are immovable at this time due to the abutment of the closed ends <NUM> thereof against wall <NUM> defining the bore in housing <NUM>.

At this time, initial top-master key <NUM> can be removed from the main key slot <NUM>, as shown in <FIG>. This permits plungers <NUM> to be biased by their respective springs <NUM> to a position where the tapered face <NUM> of each plunger <NUM> adjacent to key slot <NUM> bears against a shoulder <NUM> formed within core <NUM>. At this point, the movement of the respective plunger <NUM> is arrested. With change tool <NUM> remaining in position, a new top-master key <NUM> is then inserted in key slot <NUM>, as shown in <FIG>. This effectively biases plungers <NUM> to new positions which are determined by the geometric configuration of the milled edge of new top-master key <NUM> placed in key slot <NUM>. It also changes the relative positions of the several tips <NUM> on retainer pins <NUM> with respect to the ribs <NUM> formed around the shanks of plungers <NUM>.

After new top-master key <NUM> has been inserted, the change tool <NUM> is removed from the change tool slot <NUM>, as shown in <FIG>. This permits retainer pins <NUM> to respond to the bias of springs <NUM> exerted through active drivers <NUM> and cam plates <NUM>, and to return to their position of engagement with plungers <NUM> by extension of tips <NUM> between adjacent pairs of the spaced ribs <NUM>. It will be perceived that the effect of the actions described is to readjust the overall lengthwise dimension of the several tumbler assemblies so that they are correlated to new top-master key <NUM>, and this new top-master key, when inserted in key slot <NUM>, will result in the retainer sleeve <NUM> of the several tumbler assemblies <NUM> being biased to the shear line <NUM> necessary to open the lock as previously described. Core <NUM> may then be rotated to the basic rekey position as viewed in <FIG>.

In the basic rekey position, the new top-master key <NUM> is withdrawn and a new patron key <NUM> is inserted as illustrated in <FIG>. New patron key <NUM> typically has a different milled surface than the initial patron key <NUM>, initial top-master key <NUM> and new top-master key <NUM>. The milling of new patron key <NUM> is such that, for at least one of the several tumbler assemblies <NUM>, closed end <NUM> is within apertures <NUM> of core <NUM> and not immediately adjacent to shear line <NUM>; thus, its insertion causes master pins <NUM> to move between at least one of the inactive master-pin chambers <NUM> and the corresponding aperture <NUM> in core <NUM>. Subsequently, when core <NUM> is turned back to the key-pull position as shown in <FIG>, one or more master pins <NUM> are part of at least one of the lock stack assemblies, and the master pin interface with active driver <NUM> is shear point <NUM> used by new patron key <NUM>. As further described below in the Key Progression Section, typically the first new patron key used, after rekeying to a new top-master key, will drop all of the master pins below the shear line and bring them all into the active drive chambers. Having all the master pins in use ensures that, after future rekeys of patron keys, no previous patron keys will continue to operate the lock.

The lock is now rekeyed for the new top-master key <NUM> and new patron key <NUM>. After rekeying, the initial top-master key <NUM> can be inserted into key slot <NUM> as shown in <FIG>. As will be noted, the insertion of initial top-master key <NUM> does not result in any shear points coinciding with shear line <NUM>. Accordingly, initial top-master key <NUM> can no longer operate the lock. When new top-master key <NUM> is inserted into key slot <NUM>, the shear points <NUM> associated with end <NUM> of all the tumbler assembly <NUM> is coincident with the shear line <NUM>, as shown in <FIG>. Thus, new top-master key can operate the lock. As can be seen, master pins <NUM> are above shear line <NUM> and are within driver chamber <NUM>. Accordingly, when core <NUM> is turned, master pins <NUM> will remain within driver chamber <NUM>. Further, if initial patron key <NUM> is inserted in key slot <NUM> as illustrated in <FIG>, no shear points coincide with shear line <NUM>; thus, initial patron key <NUM> cannot operate the lock. However, when the new patron key <NUM> is inserted in key slot <NUM> as illustrated in <FIG>, then shear point <NUM> between active driver <NUM> and master pin <NUM> coincides with shear line <NUM>. Accordingly, new top-master key <NUM> and new patron key <NUM> will operate the lock after rekeying, but initial top-master key <NUM> and initial patron key <NUM> will not.

To understand the invention better, certain embodiments relating to key progressions during rekeying will now be described. As will be clear from the above, each driver chamber <NUM> has a core aperture <NUM> associated with it, and each driver chamber / core aperture combination has a pin stack associated with it. In the described embodiment, the key has a number of cut-depth positions equal to the number pin stacks in the lock, which is the same as the number of driver chamber / core aperture combinations. The described embodiments use two different bases for cut depths for each cut-depth position so as to align a shear point in the pin stack associated with the cut-depth position with the shear line <NUM>. The first cut depth (associated with the top-master key) will align bottom shear point <NUM> associated with end <NUM> of the tumbler assembly <NUM> with shear line <NUM>. The second cut depth (associated with a change key) will align the top shear point <NUM> (between the bottom of the driver and the top of the upper master pin) with the shear line <NUM>. As will be appreciated, if no master pins are in a pin stack, then the change key uses the cut depth associated with bottom shear point <NUM> aligning with shear line <NUM>.

As illustrated in <FIG>, a level <NUM> system utilizes a master key with a number of change keys under it, and each change key associated with a specific lock. For each lock associated with the master key, the rekey for the master key is in accordance with the Top-Master Rekeying method described above and the rekeying of the change key or patron keys is in accordance with the Basic Rekeying Method.

In one embodiment, a level <NUM> system lock utilizes five pin stacks and six master pins. Each master pin has a different thickness. The master pins are associated with four of the five pin stacks. For example, two pin stacks can have two master pins associated with each pin stack, two pin stacks can have one master pin associated with each pin stack and one pin stack will have no master pin associated with it. As will be appreciated, a master pin being associated with a pin stack does not mean that the master pin is in the pin stack but, rather that the master pin is either in the pin stack or in an associated inactive master-pin chamber. In this embodiment, the first change key (first patron key) used is a key associated with having all the master pins in the pin stack and no master pins in the inactive master-pin chambers. Starting from this orientation helps ensure that prior change keys cannot open locks that have been rekeyed.

In this embodiment, four of the pin stacks pin chambers are used to progress through all possible change key rekeys. The fifth pin stack is left without any master pins to help prevent unintentional cross keying and limit the total number of shear points in the cylinder.

<FIG> illustrate rekeying a lock from a first change key (<FIG>) through to a sixth change key (<FIG>). As illustrated in <FIG>, a first change key <NUM> is inserted into lock <NUM>. In lock <NUM>, a first pin stack <NUM> has two master pins <NUM> and <NUM> associated with and currently in pin stack <NUM>. A second pin stack <NUM> also has two master pins <NUM> and <NUM> associated with and currently in pin stack <NUM>. Third pin stack <NUM> has only a single master pin <NUM> associated with and currently in pin stack <NUM>. Similarly, fourth pin stack <NUM> has only a single master pin <NUM> associated with and currently in pin stack <NUM>. Finally, pin stack <NUM> has no master pins associated with it. Each pin stack <NUM>, <NUM>, <NUM>, <NUM> and <NUM> has a driver <NUM>, <NUM>, <NUM>, <NUM> and <NUM> associated with it, respectively. Also, each pin stack <NUM>, <NUM>, <NUM>, <NUM> and <NUM> has a tumbler assembly <NUM>, <NUM>, <NUM>, <NUM> and <NUM> associated with it, respectively. Each key for the lock has five cut-depth positions <NUM>, <NUM>, <NUM>, <NUM> and <NUM> associated with pin stacks <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, respectively.

When first change key <NUM> is inserted into lock <NUM>, pin stacks <NUM>, <NUM>, <NUM> and <NUM> are positioned such that upper shear points <NUM>, <NUM>, <NUM> and <NUM> align with shear line <NUM>. The upper shear points being the shear points between a master pin and the driver associated with the pin stack. Additionally, when first change key <NUM> is inserted into lock <NUM>, pin stack <NUM> is positioned such that lower shear point <NUM> is aligned with shear line <NUM>. The lower shear points being the shear points between a tumbler assembly and a master pin or, if no master pin is present in the pin stack, a driver.

The lock configuration after a first basic rekey is performed is illustrated in <FIG>. As can be seen, first pin stack <NUM> is changed so as to remove master pin <NUM>. All the other pin stacks remain unchanged. First change key <NUM> can no longer open lock <NUM> because its cut depth for first cut-depth position <NUM> will no longer be sufficient to align a shear point with the shear line. The lock is now keyed for second change key <NUM> to open the lock, as illustrated.

The lock configuration after a second basic rekey is performed is illustrated in <FIG>. As can be seen, first pin stack <NUM> is changed so as to remove master pin <NUM>; thus, first pin stack <NUM> now has no master pins in it. The master pins for first pin stack <NUM> are both located in the inactive master-pin chamber associated with first pin stack <NUM>. All the other pin stacks remain unchanged. Neither first change key <NUM> nor second change key <NUM> can open lock <NUM> because their cut depth for first cut depth position <NUM> will no longer be sufficient to align a shear point with the shear line. The lock is now keyed for third change key <NUM> to open the lock, as illustrated.

The lock configuration after a third basic rekey is performed is illustrated in <FIG>. As can be seen, first pin stack <NUM> is changed so as to contain master pins <NUM> and <NUM>. Additionally, second pin stack <NUM> is changed so as to remove master pin <NUM> (shown in <FIG>). All the other pin stacks remain unchanged. Change keys <NUM>, <NUM> and <NUM> cannot open lock <NUM>. The lock is now keyed for fourth change key <NUM> to open the lock, as illustrated.

The lock configuration after a fourth basic rekey is performed is illustrated in <FIG>. As can be seen, first pin stack <NUM> is changed so as to remove master pin <NUM>; thus, it only contains master pin <NUM>. Second pin stack <NUM> is unchanged from the previous configuration and contains only master pin <NUM>. All the other pin stacks remain unchanged. Change keys <NUM>, <NUM>, <NUM> and <NUM> cannot open lock <NUM>. The lock is now keyed for fifth change key <NUM> to open the lock, as illustrated.

The lock configuration after a fifth basic rekey is performed is illustrated in <FIG>. As can be seen, first pin stack <NUM> is changed so as to remove master pin <NUM>; thus, it contains no master pins. Second pin stack <NUM> is unchanged from the previous configuration and contains only master pin <NUM>. All the other pin stacks remain unchanged. Change keys <NUM>, <NUM>, <NUM>, <NUM> and <NUM> cannot open lock <NUM>. The lock is now keyed for sixth change key <NUM> to open the lock, as illustrated. Further, rekeyings will be apparent to one skilled in the art from the above description and the figures.

Generally, if the top-master key is to open more than one lock, the master pins in pin stacks <NUM> and/or <NUM> will be used to differentiate the locks so that the top-master key can open each lock but so that a change key from one lock will not open one of the other locks under the top-master key. However, in some situations it may be desirable to use pin stacks <NUM> and <NUM> to allow additional change keys for single lock. If so, subsequent basic rekeying can be achieved by removing the master pin from pin stack <NUM> and/or pin stack <NUM> and, for each master pin change in those stacks, following the above outlined master pin changes for pin stacks <NUM> and <NUM>.

When desirable, the top-master key can be changed by rekeying the lock in accordance with the Top-Master Rekeying Method described above. Changing the top-master key results in changing the change key (patron key). Typically, the initial change key for a new top-master key has all the master pins in the pin stacks.

As illustrated in <FIG>, a level <NUM> system utilizes a top-master key with a number of master keys under it. Each master key in turn has a number of change keys under it. In one exemplary key progression for a level <NUM> system, the top-master key is rekeyed in accordance with the Top-Master Rekeying Method described above. For each lock associated with the top-master key, the rekey for the master key and the rekeying of the change keys (patron keys) are in accordance with the Basic Rekeying Method.

In one embodiment, a level <NUM> system lock utilizes five pin stacks and eight master pins. Typically, at least six different thicknesses can be used for the master pins. Generally, the master pins are associated with all five pin stacks. For example, three pin stacks can have two master pins associated with each, and two pin stacks can have one master pin associated with each. As will be appreciated, a master pin being associated with a pin stack does not mean that the master pin is in the pin stack but, rather that the master pin is either in the pin stack or in an associated inactive master-pin chamber. In this embodiment, three pin stacks are used to progress through all possible change key rekeys, and the other two pin chambers are used to progress through all possible master key rekeys. Which pin stacks are designated for each can vary between cylinder systems to increase variations and security between systems.

Like the level <NUM> system described above the first change key and first master key combination used can be associated with having all the master pins in the pin stack and no master pins in the inactive master-pin chambers. Starting from this orientation helps ensure that prior change keys cannot open locks that have been rekeyed.

In this embodiment, the change keys use upper shear points, except in pin stacks that have no master pins in them. The master keys use a mixture of lower shear points and upper shear points, and the top-master key uses lower shear points. For example, in a level <NUM> system where pin stacks <NUM>, <NUM> and <NUM> are designated for change key rekeys, and pin stacks <NUM> and <NUM> are designated for master key rekeys, the top-master key will use the lower shear points for each pin stack; that is, the top-master key raises the top of all tumbler assemblies to shear line. The master keys coming under the top-master key raises the top of the tumbler assembly in chambers <NUM>-<NUM> to shear line thus using the lower shear point. Additionally, for pin stacks <NUM> and <NUM>, the master keys raises the top of the uppermost master pin to shear line thus use the upper shear point. Naturally, if the lock has been rekeyed to a configuration where there are no master pins in either pin stack <NUM> or <NUM>, the current master key will use the lower shear point for that pin stack. The change key will raise the top of the uppermost master pin in all pin stacks to shear line, thus using the upper shear point. Similarly as with the master keys, if the lock has been rekeyed such that a pin stack has no master pin, the current change key will use the lower shear point for that pin stack. This design forces lower-level keys to be slaves to higher-level keys.

As will be appreciated, the current lock system is very flexible and the above embodiments can be adapted in many ways. For example, different pin stacks can have zero, one, two or more master pins associated with them so as to increase the combinations of the locks. Additionally, the lock can have few than five pin stacks or more than five pin stacks. Such modifications will be readily apparent to one skilled in the art based on an examination of this disclosure.

Claim 1:
A key-operated lock (<NUM>) comprising:
a housing (<NUM>);
a core (<NUM>) rotatably mounted in the housing;
a plurality of master pins (<NUM>) in a first configuration to allow a first patron key to open the lock; and
a plurality of reconfigurable tumbler assemblies (<NUM>) in a first arrangement to allow a first top-master key (<NUM>) to open the lock;
wherein the housing, the core, the plurality of master pins and the plurality of reconfigurable tumbler assemblies are configured to have:
a key pull position in which at least the first top-master key and the first patron key are insertable into the lock so as to be able to lock and unlock the lock;
a basic rekey position in which the plurality of master pins are reconfigured by inserting a second patron key (<NUM>) into a second configuration, wherein in the second configuration, the first patron key is not able to lock and unlock the lock from the key pull position and the second patron key is able to lock and unlock the lock from the key pull position; and
a top-master rekey position in which the reconfigurable tumbler assemblies are reconfigured by insertion of a change tool (<NUM>) and a second top-master key into a second arrangement, wherein in the second arrangement the first top-master key and first patron key are not able to lock and unlock the lock from the key pull position and the second master key is able to lock and unlock the lock from the key pull position.