Patent Publication Number: US-8978426-B2

Title: Hidden shackle lock incorporating a “key-in-knob” (KiK) cylinder

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from U.S. Provisional Application No. 60/857,189 to Wei Wang filed on Nov. 7, 2006, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a hidden shackle style lock, and more particularly to a hidden shackle style lock incorporating a “Key-in-Knob” (KiK) cylinder. 
     BACKGROUND 
     In a common locking device, such as an exposed shackle type padlock, a U-shaped hinged shackle is passed through one or more rings (or through-holes), and the free end of the shackle inserted and retained in a bore on the housing of the padlock. The rings are now said to be locked using the padlock. In such an exposed shackle type locking device, the shackle is exposed, and therefore prone to attack (applying torque to the shackle, applying a tension force to the shackle, cutting the shackle, etc.). A hidden shackle style locking device (hereinafter referred to as a ‘hockey puck lock’) is sometimes used to prevent access to the shackle and thereby reduce such attack. A hockey puck lock has a generally stubby cylindrical shape with a rounded front and back surface. The rounded back surface defines a generally rectangular cavity to receive one or more parallel plates (which are to be locked together) with mating through-holes. A cylindrical shackle coupled to a central cylinder having a locking mechanism therein is slidably disposed on the housing to lock the one or more parallel plates together. To lock the parallel plates together using such a hockey puck lock, the parallel plates with the mating through-holes are located within the rectangular cavity, and the shackle is slid through these through-holes. An operator key is then used to activate locking pins in the central cylinder allowing the shackle to rotate and, thereby, engage with locking feature provided in the housing. When the shackle turns, a groove or a tab formed on the tip of the shackle engages with a corresponding geometry within the cylindrical cavity, thereby locking the shackle in place. 
     A KiK cylinder is a type of central cylinder with a locking mechanism that is commonly available in the market. For instance, common residential front door locks incorporate KiK cylinders in their design. Due to the wide popularity of KiK cylinders, and their wide spread use in a variety of locking applications, the outer dimensions of the KiK cylinders have been standardized. The working part of the cylinder (the part which interacts with the lock housing) uses an intermediary called a tail piece or a driver to adapt to a particular brand of lock. Generally, there are three versions of tail pieces used to accommodate the various types of KiK cylinders. These versions of tail pieces are named, “the schlage® driver,” “the lori driver,” and “medeco® driver,” after major lock suppliers whose locks these drivers are designed to interface with. It should be noted, however, that each of these drivers can be used with KiK cylinders from a number of lock manufacturers. For instance, the schlage® driver can be used with KiK cylinders from lock manufacturers other than Schlage®. Due to the wide availability of KiK cylinders, it would be advantageous to incorporate the KiK cylinder in a hockey puck lock. 
     In a common lock incorporating a KiK cylinder, the KiK cylinder is slid into the housing (in a longitudinal direction) of the lock, locked in place, and then used to operate the lock. Operating the lock allows a shackle to move in a plane perpendicular to the longitudinal axis of the KiK cylinder to lockingly engage with a locking feature. In a hockey puck lock, however, the locking operation requires the shackle (along with the attached central cylinder) to slide along its longitudinal axis before it lockingly engages with the locking features in the lock housing. That is, if sliding along the longitudinal axis is utilized to insert the KiK cylinder in a hockey puck lock, unlocking the lock may also cause the KiK cylinder to be separated from the housing. Therefore, incorporating a KiK cylinder into a hockey puck lock, without causing the KiK cylinder to detach from the lock housing every time the lock is unlocked, is challenging. 
     The present disclosure relies on novel design features to incorporate a KiK cylinder in a hockey puck lock. 
     SUMMARY OF THE INVENTION 
     In one aspect, a hidden shackle style lock is disclosed. The lock has a substantially cylindrical housing having a top surface, a bottom surface, and a curved side surface. The lock also has a first cavity on the bottom surface of the housing which extends part way along a thickness of the housing, and a second cavity on the side surface intersecting with the first cavity. The lock further includes has a hollow sleeve slidably attached within the second cavity. The sleeve has a first end face, a second end face, and a third cavity. The third cavity extends from the first end face to the second face and is substantially coaxial with the second cavity. A shackle is coupled to the first end face of the sleeve. A core member with a locking mechanism is disposed within the third cavity and coupled to the shackle. A driver member is located between the core member and the shackle and couples the core member to the shackle. 
     In another aspect, a hidden shackle style lock is disclosed. The lock has a substantially cylindrical housing with a top surface, a bottom surface, and a curved side surface. The lock also has a first cavity in the bottom surface extending part way along a thickness of the housing, and a second cavity in the side surface that intersects the first cavity. A sleeve is slidably attached within the second cavity, and a shackle assembly is fixedly attached to the sleeve. The shackle assembly includes a shackle member with locking features at one end and first mating features at an opposite end. The shackle assembly also includes a KiK lock cylinder with a key hole at one end and second mating features at an opposite end. A driver member, positioned between the shackle member and the KiK lock cylinder, interfaces with the first mating features and the second mating features. 
     In yet another aspect, the method of using a hidden shackle style lock having a KiK cylinder as a locking mechanism is disclosed. The method includes, slidably attaching a hollow sleeve within a first cavity of a housing of the lock, and coupling a shackle having a locking feature to the sleeve. The method also includes coupling a driver to the shackle, and coupling a first design feature of the KiK cylinder to a mating second design feature of the driver. The method further includes fixedly attaching the KiK cylinder to the sleeve, and inserting a hasp with a hole into a second cavity of the housing. The method further includes sliding the shackle through the hole in the hasp, and operating the locking mechanism to rotate the shackle and lockingly engage the locking feature to mating features in the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic illustration of an exemplary disclosed hockey puck lock; 
         FIG. 2  illustrates an exploded view of the hockey puck lock of  FIG. 1 ; 
         FIG. 3  illustrates an exemplary sleeve of the lock of  FIG. 1 ; 
         FIG. 4  illustrates an exemplary shackle assembly of the lock of  FIG. 1 ; 
         FIG. 5A  illustrates an exploded view of an exemplary sleeve, shackle assembly, driver, and lock core of the lock of  FIG. 1 ; 
         FIG. 5B  illustrates the assembled configuration of the components of  FIG. 5A ; and 
         FIG. 6A-C  illustrates three exemplary drivers for use with the lock of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a hidden shackle style lock (locking device  100 ). The locking device  100  comprises a housing  5  having a generally circular cross-section with a generally circular front portion  10 , a generally circular back portion  12 , and a generally cylindrical side surface  14 . It is also contemplated that the front portion  10 , the back portion  12 , and the side surface  14  may have other shapes. The front portion  10  and the back portion  12  may be planar or may be made up of multiple planar surfaces. The side surface  14  of the locking device  100  may include a side cavity  32  to insert the locking mechanism of the locking device  100 . In some embodiments, the cross-section of the side cavity  32  (along a plane perpendicular to the front portion  10 ) has a rounded rectangular shape. However, the cross-section of the side cavity  32  may have other shapes, such as a square or an oval shape. One or more keys may also accompany the locking device  100 . These keys may include an operator key  16 . The operator key  16  may be used to lock and unlock the locking device  100 . 
       FIG. 2  illustrates the components that make up the locking system  100 . The circular back portion  12  of the locking system  100  may be made of two planar surfaces—a first semi-circular portion  13  and a second semi-circular portion  15 . In some embodiments, the first semi-circular portion  13  may be offset from the second semi-circular portion  15 . It is contemplated that the back portion  12  may be made of one planar surface. It is also contemplated that the first semi-circular portion  13  and a second semi-circular portion  15  may have other shapes. The first semi-circular portion  13  may include a blind cavity  24 . The blind cavity  24  may extend for a significant thickness of the locking device  100 , but may not extend all the way to the front portion  10 . The cross-section (along a plane parallel to the front portion  10 ) of the blind cavity  24  may be of a generally rectangular shape with rounded sides and edges. In some embodiments, the blind cavity  24  may be of another shape, such as a square, an oval, an elongated oval, or any other shape. The blind cavity  24  may have a first internal side wall  23  and a second internal side wall  25  which is opposite to the first internal side wall  23 . The first internal side wall  23  may include a first cavity  26 , and the second internal side wall  25  may include a second cavity  27 . In one embodiment, the first cavity  26  may not protrude through the side surface  14  of the locking device  100 . The first cavity  26  may have a generally cylindrical shape (other shapes are also possible). The second cavity  27  may join with the side cavity  32  extending from the side surface  14  of the housing  5 . In some cases, the second cavity  27  may be the same as the side cavity  32 . The first cavity  26  and the second cavity  27  may have their longitudinal axes parallel to each other. In some cases, the longitudinal axes of the first cavity  26  and the second cavity  27  may be collinear. The blind cavity  24  may receive and enclose the eyes  74  of a hasp and keeper  70  associated with a device to be locked by the locking device  100 . 
     In this disclosure, the terms hasp and keeper  70  are used to designate two members used to lock doors and the like, which have forward projecting apertured eyes  73  adapted to be locked together, as by a padlock or a locking device  100 . The hasp and keeper  70  may be fastened to the door structure by plates, pads, or any other fastening device. The hasp  70  may be mounted on the door (or the movable portion) while the keeper  70  may be mounted on a frame (or the fixed portion), but such plates may be reversed, or may be used with two movable doors (such as a double door), or any other kind of door. When the doors are closed, the eyes  73  of the hasp and keeper  70  may project from the face of the door structure in a face-to-face parallel relationship. To lock the closed door, the locking device  100  may be placed on the door such that the back portion  12  of the locking device  100  may be parallel to the face of the door and the forward projecting portions of the hasp and keeper  70  projects into the blind cavity  24  of the locking device  100 . In this position, the eyes  73  of the hasp and keeper  70  may line up with both the first cavity  26  and the second cavity  27  in such a way that a straight shackle  44  inserted through the second cavity  27  may pass through the eyes  73 , and into first cavity  26 . 
     The back portion  12  of the locking device  100  may also have multiple pin slots  30  through which pins  28  may be inserted. A portion of the inserted pins  28  may pass through the first cavity  26  such that a cross-section of the first cavity  26  through the pins  28  reveal the circular cross-section of the first cavity  26  with the cross-section of each pin  28  occupying a segment of the circle on opposite sides. The portion of the pins  28  passing though the first cavity  26  may serve as locking flanges. As will be described in more detail below, the locking flanges formed by pins  28  in the first cavity  26  receive mating flanges of the shackle assembly  45  to lock the locking device  100 . 
     The back portion  12  may also include a retaining hole  22  through which a retaining screw  20  passes. The retaining screw  20  may be threaded on its external surface. The internal surface of the retaining hole  22  may also be threaded to mate with threads on the retaining screw  20 . The longitudinal axis of the retaining hole  22  may perpendicularly intersect the longitudinal axis of the side cavity  32  located on the side surface  14  of the housing  5 . When the retaining screw  20  is screwed into the retaining hole  22 , a portion of the retaining screw may protrude into the side cavity  32 . 
     A sleeve  34  may be inserted into the side cavity  32  such that the longitudinal axis of the sleeve  34  is substantially collinear with the longitudinal axis of the side cavity  32 . The sleeve  34  may have the shape of a hollow rectangular prism with rounded sides and parallel end surfaces—top surface  35  and bottom surface  37 . The shape of the internal surface of the side cavity  32  may resemble the shape of the external surface of the sleeve  34 , such that the external surface of the sleeve  34  and the internal surface of the side cavity  32  form curved mating surfaces. The term curved mating surfaces are used to refer to surfaces that, at any location, may be substantially parallel to each other. That is, the tangent at any point on one surface is substantially parallel to a tangent from the corresponding point of the other surface (for example, a hand and glove relation ship). A cross-section of the housing  5  along a plane perpendicular to the longitudinal axis of the side cavity  32  may reveal the sleeve  34  to have a rectangular cross-section with rounded sides circumscribed by the internal surface of the side cavity  32 . The external dimensions of the sleeve  34  and the internal dimensions of the side cavity  32  may be such that the sleeve may be able to slide freely within the side cavity  32  without interference. It is also contemplated that portions of the external surface of the sleeve  34  may be in contact with the internal surface of the side cavity  32 . 
     The sleeve  34  may also include an outer first surface  33  with a keyway  36 . The keyway  36  may be a slot formed on the first surface  33  which extends part way through the thickness of the first surface  33 . In some embodiments, the keyway  36  may extend through the entire thickness of the first surface  33 . The keyway  36  may be formed on the center of the first surface  33  and may extend longitudinally over part of the length of the sleeve  34 . The keyway  36  does not extend to the ends of the sleeve  34 . When the sleeve  34  is inserted into the side cavity  32  of the housing  5  and the retaining screw  20  fastened to the retaining hole  22 , the retaining screw  20  may extend into the keyway  36 . The dimensions of the retaining screw  20  may be such that it permits the sleeve  34  to slide feely (travel) a certain distance within the side cavity  32  while preventing the sleeve  34  from being pulled out of the side cavity  32 . 
       FIG. 3  shows a view of the sleeve  34  with its internal surfaces visible. In the description of the sleeve  34  that follows, reference will be made to both  FIGS. 2 and 3 . The cross-section (along a plane parallel to the top surface  35 ) of the internal surface of the sleeve  34  may reveal intersecting circles resembling a figure “8”. With such a shape, the internal surface of the sleeve  34  may have curved and projecting surfaces  39 . The projecting surfaces  39  may be opposite to each other and may protrude into the hollow internal cavity  38  of the sleeve  34 . When the sleeve  34  is inserted into the side cavity  32 , the top surface  35  of the sleeve  34  may be exposed and visible from the side surface  14  of the locking device  100 . The bottom surface  37  of the sleeve  34 , opposite to the top surface  35 , may have a closure plate  41  with a threaded hole  48  that covers one lobe of the intersecting circle while leaving open the other lobe. The open lobe may have a stepped recess  40  (visible in  FIG. 5A ) that acts as a seat for a shackle assembly  45 . 
       FIG. 4  shows a shackle assembly  45  may include a shackle  44  having a substantially cylindrical shape. A rear end portion of the shackle  44  may include a pair of locking flanges  42 . In some embodiments, the locking flanges  42  may be a machined feature on the shackle  44 . It is also contemplated that the shackle  44  may be of another shape and the locking flanges  42  be formed by some other process, such as by fastening a separate locking flange section to the shackle  44 . A forward end portion  146  of the shackle assembly  45  may include an elongated slot  46 . The forward end portion  146  of the shackle assembly  45  may have larger diameter than the shackle  44 . This larger diameter section may rest on the stepped recess  40  of the sleeve  34  when the shackle assembly is disposed within the hollow internal cavity  38 . The elongated slot  46  may be machined on the shackle, or may be formed on a separate part which is then attached to the forward end portion  146  of shackle  44 . 
       FIG. 5A  shows an exploded view of a lock core  61  that may be coupled to the forward end portion  146  of the shackle assembly  45 .  FIG. 5B  shows the components of  FIG. 5A  assembled together. In the explanation that follows, reference will be made to both  FIGS. 5A and 5B . The lock core  61  may include a KiK cylinder  60  and a cylinder retaining plug  66 . The KiK cylinder  60  may have a generally cylindrical shape with two opposite parallel surfaces—a front surface  63 , and a tail  64 —as its end faces, and a curved surface between them. The curved surface of KiK cylinder  60  may include a bible  62  extending longitudinally along the KiK cylinder  60 . The bible  62  may have a generally rectangular cross-sectional shape along a plane perpendicular to a longitudinal axis of the KiK cylinder  60 . However, other cross-sectional shapes of the bible  62  are also contemplated. The cylinder retaining plug  66  may have a cylindrical shape and, in general, may have a size comparable to that of the KiK cylinder  60 . The cylinder retaining plug  66  may include a cavity  67  extending longitudinally along a curved external surface. The cross-sectional shape of the cavity  67  may match that of the bible  62 . The bible  62  may be inserted into the cavity  67  of the cylinder retaining plug  66  to couple the two parts together and form a lock core  61 . In the coupled configuration, the cross-sectional shape of the lock core  61  along a direction perpendicular to its longitudinal axis may resemble a figure “8.” The cross-sectional shape of the lock core along a plane perpendicular to the longitudinal axis of the KiK cylinder  60 , may be substantially similar to the cross-sectional shape of the hollow internal cavity  38  of the sleeve  34 . 
     The front surface  63  of lock core  61  may include a key hole that accepts an operator key  16 . The tail  64  may have features configured to couple with the shackle assembly  45 . The features on tail  64  may different configurations depending upon the manufacturer of the KiK cylinder  60 .  FIG. 5A  depicts a KiK cylinder  60  manufactured by Schlage®. The tail  64  of the Schlage® KiK cylinder  60  may include pins  78  protruding from the tail  64 . Tail  64  of KiK cylinders manufactured by other manufacturers may include other features. For example, cavities or protrusions in a specific pattern. In general, the tail  64  may have one of three standard configurations (as found in KiK cylinders manufactured by Schlage®, Medeco®, and Lori companies). KiK cylinders from Medeco® and Lori companies may have cavities along a diagonal of the tail  64 . 
     A first driver  68  may couple the tail  64  end of the lock core  61  to the forward end portion  146  of the shackle assembly  45 .  FIG. 6A  shows multiple views of the driver  68 . The first driver  68  may include a rectangular protrusion  74  at one end to mate with the elongated slot  46  on the forward end portion  146  of the shackle assembly  45 . The opposite end of the first driver  68  may include one or more curved recess  76  configured to mate with the one or more pins  78  extending from the tail  64  of KiK cylinder  60 .  FIGS. 6B and 6C  show multiple views of a second driver  168  and a third driver  268 , respectively. The second and third drivers  168  and  268 , may also include the rectangular protrusion  74  to mate with the elongated slot  46  of the shackle assembly  45 . The opposite end of the second and third drivers  168  and  268 , may have different features to mate with tail features of KiK cylinders from different manufacturers. For instance, second driver  168  may have a rectangular protrusion  176  sized to mate with a rectangular cavity on the tail  64  of a KiK cylinder manufactured by Medeco® company. Likewise, third driver  268  may have a rectangular protrusion  276  sized to mate with a rectangular cavity on the tail  64  of a KiK cylinder manufactured by Lori company. 
     As best seen in  FIG. 5A , a retaining ring  84  may couple the first driver  68  to the lock core  61 . The retaining ring  84  may have internal threads that mate with external threads on the external cylindrical surface of the KiK cylinder  60 . To couple the first driver  68  to the lock core  61 , the curved recesses  76  of the first driver may be mated with the pins  78  on the tail  64  of KiK cylinder  60 . The retaining ring  84  may now be slipped over the first driver  68  and the internal threads of the retaining ring  84  screwed on the external threads of the KiK cylinder  60 . The first driver  68  may now be snugly coupled with the lock core  61 . The second and the third driver  168  and  268 , may also be similarly coupled with appropriate KiK cylinders. In the coupled configuration, the rectangular protrusion  74  may protrude from one end of the lock core  61 . The rectangular protrusion  74  may mate with the elongated slot  46  of the shackle assembly  45 . A stopper  82  may be sandwiched between the lock core  61  and the shackle assembly  45 . The stopper  82  may restrict the rotation of the first driver  68  to only the clockwise direction. 
     To couple the lock core  61  to the shackle assembly  45  and the sleeve  34 , as seen in  FIG. 5B , the KiK cylinder  60  is first coupled with the retaining plug  66  to form the lock core  61 . The first driver  68  may then be coupled to the tail  64  of the KiK cylinder  60  using the retaining ring  84 . The shackle assembly  45  may then be inserted into the hollow internal cavity  38  of the sleeve  34 , such that the shackle  44  protrudes through the exposed lobe on the bottom surface  37  of the sleeve  34 . In this inserted configuration, the forward end portion  146  of the shackle assembly  45  may rest on the stepped recess  40  of sleeve  34 , with the elongated slot  46  visible through the hollow internal cavity  38 . The coupled lock core  61  with the stopper  82  may be inserted into the hollow internal cavity  38  to mate the rectangular protrusion  74  of the first driver  68  with the elongated slot  46  of the shackle assembly  45 . A threaded screw  47  may then be screwed into a threaded cavity of the retaining plug  61  through the threaded hole  48  on the closure plate  41  to secure the lock core  61  to the sleeve  34 . 
     With the shackle assembly  45  and the lock core  61  attached to the sleeve  34 , the sleeve  34  may be inserted into the side cavity  32  of housing  5 . The sleeve  34  may be secured to the housing  5  using the retaining screw  20  (see  FIG. 2 ). The retaining screw  20  protrudes into the keyway  36  of the sleeve  34  allowing the sleeve  34  (along with attached shackle assembly  45  and lock core  61 ) to slide in the housing  5 , while preventing them from being detached from the housing  5 . The distance of allowable sliding may depend on the length of the keyway  36 . The lengths of the keyway  36  may be such that the locking flanges  42  on the rear end portion of the shackle  44  may travel the entire thickness of the blind cavity  24  and the depth of the first cavity  26  to lockingly engage with locking features therein. 
     INDUSTRIAL APPLICABILITY 
     Hidden shackle style locks are widely used as high security locking devices since their shackles are inaccessible to an unauthorized person, and therefore difficult to cut. KiK cylinders are the mainstay of most residential and commercial locking devices. The disclosed locking device  100  retains the advantages of conventional hidden shackle style locks while incorporating the convenience of using a commonly available KiK cylinder as the locking mechanism. A conventional hockey puck lock is modified to include a hollow sleeve  34  to interface with the KiK cylinder  60  and the housing  5  of the locking device  100 . A shackle assembly  45  with a shackle  44  is also rigidly attached to the KiK cylinder  60  with their longitudinal axes parallel to each other. The sleeve  34  is slidably disposed on the housing  5  of the locking device  100 , and is secured to the housing  5  using a retaining screw  20 . The retaining screw  20  permits the sleeve  34  and the shackle  44  to slide along their longitudinal axis, while preventing them from being detached from the housing  5 . 
     A commonly available KiK cylinder  60  is coupled to a cylindrical retaining plug  66  and disposed within the internal cavity  38  of the sleeve  34 . When the KiK cylinder  60  is thus disposed, features at the tail end of the KiK cylinder  60  mates with corresponding features on a top surface of the shackle assembly  45 . In this configuration, operating the locking mechanism of the KiK cylinder  60 , allows the shackle  44  to rotate and engage with locking features of the lock housing  5 . To accommodate KiK cylinders from different manufactures which may have different features at the tail end  64 , a driver is coupled to the tail end of KiK cylinder to act as an intermediary between the mating features of the KiK cylinder and the corresponding features of the Shackle assembly. Three different drivers, each having design features to accommodate a different tail end mating feature, are provided to permit the use of most commonly available KiK cylinders with the locking device  100 . 
     The operation of the locking device  100  will now be briefly described. The doors to be locked using the locking device  100  is closed such that the hasp  70  mounted on the door and the keeper  70  mounted on a frame beside the door project outwards from the face of the door structure in a face-to-face parallel relationship. In this orientation, the eyes  74  of the hasp and keeper  70  may be in line with each other. That is, the longitudinal axis of the eyes  74  may be substantially collinear. 
     The locking device  100  may be placed on the door such that the back portion  12  of the locking device  100  may be flush with the face of the door, with the forward projecting portions of the hasp and keeper  70  projecting into the blind cavity  24  of the locking device  100 . In this position, the eyes  74  of the hasp and keeper  70  may line up with the first cavity  26  and second cavity  27  of the locking device  100 . The sleeve  34  (along with the attached shackle assembly  45  and the lock core  61 ) may be pushed into the side cavity  32  such that the top surface  35  of the sleeve is closest to the side surface  14  of the housing  5 . In this position, the shackle  44  passes through the eyes  74  of the hasp and keeper  70 , and into the first cavity  26 . The operator key  16  may then be inserted into the key hole on the front surface  63  of the KiK cylinder  60  and turned. If the correct key is used, the locking mechanism of the KiK cylinder  60  operates, rotating the shackle  44 . When the shackle  44  rotates, the locking flanges  42  at the end of the shackle  44  engages with the pins  28  (locking features) within the first cavity  26 . When the locking feature  42  engages with the pins  28 , the shackle  44  is prevented from being pulled out of the first cavity  26 , thereby locking the hasp and keeper  70  together. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed hidden shackle style lock. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the hidden shackle style lock disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.