Patent Publication Number: US-8978428-B2

Title: Apparatus for automatically returning a lock to a desired orientation

Description:
PRIORITY CLAIM 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/532,175, filed Sep. 8, 2011, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention is related to an apparatus that automatically returns a cylinder plug lock to a home rotational position after a rotational force that rotates the cylinder plug away from the home rotational position is removed. 
     BACKGROUND 
     In a typical pin tumbler lockset—also known as a cylinder lock—there is a cylinder plug mounted for rotation within a housing. When the cylinder plug is rotated, it actuates a lockset mechanism to pull in a latch or activate a deadbolt function to lock or unlock the door. The movement of the lockset mechanism is based on the rotation of a properly bitted key inserted into a keyway in the cylinder plug, and a cam or tailpiece is attached to the cylinder plug and is coupled to the lockset mechanism. Twisting the key rotates the plug, thereby turning the cam or tailpiece and actuating the locket mechanism. 
     Mechanically keyed cylinders require that the cylinder plug be returned to the home, or “locked,” position in order to remove the key. This is due to the fact that the key is captured by the pin tumblers of the cylinder until the cylinder plug is rotated back to the home position and the pin tumblers can disengage the key, thereby permitting the key to be removed from the keyway. Thus, after opening the lock, the user must rotate the key back to the locked position before he can withdraw his key from the lock. This ensures that the cylinder plug, and any cam or tailpiece attached to the plug, is positioned back in the home or “locked” position as well. Typically, the cam or tailpiece is rotated away from the lockset mechanism and is in a position out of the way of any of the lockset drive mechanism when the cylinder plug is in the locked rotational position. For one-way doors, such as emergency exit doors that are locked from the outside but are unlocked from the inside in case emergency exit through the door is required, moving the cam or tailpiece away from the lockset mechanism ensures that the cam or tailpiece will not interfere with the lockset in any manner that may affect the ability to actuate the lockset and open the door from inside. 
     Certain electronic variations of the cylinder lock have a thumb turn or “knob” coupled to the lockset—e.g., via a “plug”—and do not include pin tumblers or do not employ a mechanical key to actuate the cylinder/lockset mechanism. An electronically-controlled (e.g., by an electric motor or solenoid) blocking element is configured to selectively block or permit rotation of the knob and the cylinder plug. In the locked condition, the blocking element is configured in a state that blocks rotation of the knob and the cylinder plug. When a valid credential, which may, for example, comprise an RFID tag, is presented by the user to a reader of the electronic lock, the state of the blocking element is electronically altered to an unlocked condition that permits rotation of the knob. With the blocking element in the unlocked condition, the user can rotate the knob which is coupled to the cam or tailpiece through the plug (as is in the mechanical cylinder lock) and operate the lockset mechanism. In this example, there is no key captured within the lock which requires that the user return the cylinder plug back to the home, or locked, position so that the key can be removed. Nevertheless, it is necessary for the user to manually return the knob attached to the cylinder plug back to the home position in order to relock the cylinder plug and move the cam back to the home position to disengage the lockset mechanism. If the knob is not returned to the locked position, for example, if the user simply forgets to return the knob to the locked position, the cylinder plug will remain in the unlocked condition, thereby cause a security lapse. In addition, the cam or tail piece will not be returned to a home position and may be left stranded in a position engaged with the lockset. This could interfere with operation of the lockset. For example, for doors that are locked on one side and opened on the opposite side, interference with the lock set could prevent opening of the door from the opened side. 
     Relying on the user to remember to manually return the cylinder plug to the locked, home position to ensure that the cylinder lock is relocked or to ensure that the cam attached to the plug is returned to the home position, is not ideal. 
     Thus, there is a need in cylinder locks that must be returned to the home, or locked, position to provide an automatic return feature that automatically returns the cylinder plug to the home position. 
     SUMMARY OF THE INVENTION 
     Aspects of the invention are embodied in a cylinder lock including a spring-biased cylinder plug return mechanism that automatically returns the cylinder plug to a home position when the plug is released by the user. In one embodiment, the plug is coupled to the knob by which a user rotates the plug from a locked position to an unlocked position, and the plug is released when the user releases the knob. 
     In a first embodiment of the invention, a torque spring is used. One end of the torque spring is attached to the shell that is fixed. The other end of the torque spring is attached to a rotating collar that is affixed to the plug and rotates in conjunction with the plug. The plug is rotatable within the shell. When the plug is rotated from an original, or home, or locked, rotational position, the collar also rotates, and the torque spring is loaded with rotational force-generating elastic potential energy. When the plug is released, the torque spring releases the stored energy and rotates the plug and collar back toward the original, or home, or locked, position at zero degrees. This design may include hard stops that limit the amount of rotation of the plug to less than 180 degrees to ensure that the torque spring returns the plug and collar in the opposite direction from which it was rotated. 
     In a second embodiment of the invention, a spring loaded slider interacts with a projection extending from a shaft of the knob that is rotatable with, or is an extension of, the plug, such as a drive pin attached to the shaft. The spring-biased cylinder plug return mechanism includes a slider having a cylindrical body that surrounds the shaft and an angled cam surface that engages the drive pin and a return spring. The slider and the shaft/plug are rotatable with respect to each other so that the shaft can rotate freely inside the slider. The slider is keyed to the shell or housing to prevent rotation of the slider with the plug. The slider is free to move forward and backward in an axial direction with respect to the plug. 
     The axial position of the slider is biased outwardly, away from the housing, by the return spring, and the slider axial travel is limited by the drive pin on the shaft. As the knob and shaft are rotated (thereby rotating the plug), the angled cam surface of the slider stays in constant contact with the drive pin due to the outward spring force on the slider by the return spring. The cam surface is preferably a flat surface oriented at an acute angle (e.g., 45 degrees) with respect to the longitudinal axis of the shaft (and cylinder plug). The angled cam surface of the slider engages the drive pin when the shaft is rotated, and, in cooperation with the return spring, causes the slider to move axially forwards (toward the knob and away from the housing) or backwards (away from the knob and towards the housing) depending on the position of the drive pin in the rotation of the knob shaft. When the slider is moved backwards toward the shell the return spring is compressed. When the knob is released, the spring will cause the slider to move toward the knob, the drive pin, which is attached to the shaft, will be moved along the cam surface to its home position, and the knob will be correspondingly rotated to the home position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an electronic, thumb-turn cylinder lock assembly embodying aspects of the present invention. 
         FIG. 2  is a perspective view of a first embodiment of a thumb-turn cylinder lock embodying aspects of the present invention. 
         FIG. 3  is a side view of the electronic, thumb-turn cylinder lock of  FIG. 2  with a spring collar omitted. 
         FIG. 4  is a rear-end perspective view of the thumb-turn cylinder lock of  FIG. 2  with the spring collar omitted. 
         FIG. 5  is a side view of the thumb-turn cylinder lock of  FIG. 2  with the spring collar and the cylinder housing omitted. 
         FIG. 6  is a rear-end perspective view of the thumb-turn cylinder lock of FIG.  2  with the spring collar, housing, retainer plate, cam, and cam retainer plate omitted. 
         FIG. 7  is a perspective view of a second embodiment of a thumb-turn cylinder lock embodying aspects of the present invention. 
         FIG. 8  is a perspective view of the thumb-turn cylinder lock of  FIG. 7  with the cylinder housing, return spring, and collar omitted. 
         FIG. 9  is a side view of the thumb-turn cylinder lock of  FIG. 7  with the cylinder housing and the collar omitted, and with the thumb-turn knob in a home position. 
         FIG. 10  is a side view of the thumb-turn cylinder lock of  FIG. 7  with the cylinder housing, return spring, and collar omitted, and with the thumb-turn knob turned approximately 90 degrees from the home position. 
         FIG. 11  is a side view of the thumb-turn cylinder lock of  FIG. 7  with the cylinder housing, return spring, and collar omitted, and with the thumb-turn knob turned 180 degrees from the home position. 
         FIG. 12A  is a front perspective view of the collar. 
         FIG. 12B  is a rear perspective view of the collar. 
         FIG. 12C  is a rear end view of the collar. 
         FIG. 13  is a side view of a typical mortise lock assembly with a cylinder lock embodying aspects of the present invention incorporated therein. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic, thumb-turn cylinder lock assembly including an electronic, thumb-turn cylinder lock embodying aspects of the present invention is indicated by reference number  10  in  FIG. 1 . The assembly  10  includes the thumb-turn cylinder lock  20  embodying aspects of the present invention, a reader box  12  with a battery  16  and a box cover  14  mounted on a mounting plate  18 . The reader box  12  includes electronic components for controlling functions of the lock  20 , including a micro-controller. The micro-controller of the reader box  12  may comprise a microprocessor in communication with memory, such as, electronically erasable programmable read-only memory (EEPROM), and is associated with functions related to the operation of the lock  20 , such as comparing information, executing algorithms to effect operation of the lock, and storing information relating to authorization codes (e.g., access credentials), passwords, lock activation events (e.g., audit events, such as, entry), and other data. The reader box  12  further includes an access control reader that receives access signals from, e.g., a access card, fob, or other device. The signals may comprise authentication codes (e.g. access credentials). The electronics of the reader box  12  are powered by the battery  16 . In an alternative embodiment, the reader box  12  may be connected to AC power as an alternative to, or in addition to, the battery  16 . 
     Details of the cylinder lock  20  are shown in  FIGS. 2-6 . As shown in  FIGS. 2 and 3 , the lock  20  includes a cylinder housing, or shell,  30 , a thumb-turn knob  22 , and a wire-connector  38  for connecting the lock  20  to the reader box  12 . As shown in  FIGS. 5 and 6 , the lock  20  includes a cylinder  29  which comprises a cylinder plug  28  (or plug), rotatably disposed within the housing  30 , and a shaft  24  extending from the plug  28 . As shown in  FIG. 3 , the thumb-turn knob  22  is attached to the shaft  24 . The cylinder lock  20  is coupled to a door lock assembly by a cam  34 . As shown in  FIG. 4 , the cam  34  is attached to and rotatable with the plug  28  by means of a cam retainer  36  that is secured to the cylinder by screws or other mechanical fasteners. In an alternate embodiment, not shown, a tail piece may extend from the plug  28  and be coupled to a door latch or deadbolt assembly. 
     Rotation of the plug  28  within the housing  30  is controlled by a sidebar  46  that is engageable with a longitudinal slot  44  formed in the plug  28  (see  FIGS. 5 and 6 ). The sidebar  46  is biased radially inwardly relative to the axis of rotation of the plug  28 . 
     The electronic lock assembly comprises a motor  48  with rotating tumblers  50  disposed on a shaft of the motor  48  and a printed circuit board (PCB)  40  that is in communication with the motor  48  and the reader box  12  via the wire connector  38 . The PCB  40  includes a microcontroller, which may comprise a microprocessor in communication with memory, such as EEPROM, and is associated with functions related to the operation of the lock  20 , such as comparing information, executing algorithms to effect operation of the lock, and storing information relating to authorization codes (e.g., access credentials), passwords, lock activation events (e.g. audit events, such as, entry), and other data. The microcontroller of the PCB  40  receives signals from the reader box  12  via the wire connector  38 . 
     Release of the sidebar  46  is controlled by the tumblers  50  attached to a shaft of the motor  48 . Each of the tumblers  50  includes a tumbler slot  54 . When the lock  20  is in a locked condition, the tumbler slots  54  of the tumblers  50  are not aligned with each other, and preferably none of the slots  54  is aligned with the top portion of the sidebar  46 . Accordingly, the sidebar  46  is prevented from disengaging from the longitudinal slot  44  by the tumblers  50 , and rotation of the plug  28  is prevented. When a valid credential is presented to the reader box  12 , the access credential codes are compared and confirmed within the reader box  12  and/or the PCB  40 , and the PCB  40  transmits an unlocked signal to the motor  48  which rotates the tumblers  50  in a first direction that will cause the tumbler slots  54  to align with each other and with the top of the sidebar  46 . Accordingly, when torque is applied to the plug  28  via the thumb-turn knob  22  and shaft  24 , the end of the sidebar  46  is forced out of the longitudinal slot  44 , and the plug  28  is able to rotate. When the plug  28  is returned to the home, or locked, position so that the longitudinal slot  44  is aligned with the sidebar  46 , a biasing element, such as a spring (not shown) urges the sidebar  46  back into the longitudinal slot  44 . 
     In one embodiment, a sensor element in the PCB  40  detects a magnet disposed within the cylinder  29 , such as in the plug  28 , to indicate that the plug  28  has been returned to the home position. Upon detecting that the plug  28  has been returned to the home position, the PCB  40  sends a lock signal to the motor  48 , which rotates the tumblers  50  in an opposite direction to scramble the tumblers  50  so that the tumbler slots  54  are no longer aligned with each other. 
     A torsional spring  32  is arranged coaxially over the shaft  24 . One end of the spring  32  is attached to a collar  26  that covers the spring  32  and is rotatable with the cylinder  29 , and another portion  42  of the spring  32  is anchored in a retainer plate  52  that is attached to the housing  30  by mechanical fasteners, such as screws. In another embodiment, one end of the spring  32  is attached to the knob  22 , and the other end is attached to the housing  30 . When the thumb-turn knob  22  and shaft  24  are rotated when the lock  20  is unlocked, the torsional spring  32  is loaded to increase the potential energy stored in the spring  32 . Thus, when the thumb-turn knob  22  is released, the thumb-turn knob  22 , shaft  24 , and plug  28  are returned to the home, or locked, position by the torsional return force stored in the spring  32 . Thus, the spring  32  comprises a spring-biased cylinder return mechanism. 
     Preferably, the lock  20  includes hard stop elements (not shown) that prevent the thumb-turn knob  22  and shaft  24  from being rotated more than 180 degrees, which can cause the spring  32  to bind. 
       FIG. 7  is a front perspective view of an alternate embodiment of a thumb-turn cylinder lock  60  embodying aspects of the present invention. The cylinder lock  60  includes a cylinder housing  82  that contains a rotatably mounted cylinder (not shown in  FIG. 7 ) and a thumb-turn knob  22  attached to a shaft that comprises an extension from the cylinder or an extended portion of the cylinder projecting from the cylinder housing  82 . The lock  60  further includes a collar  84  that houses a thumb-turn return mechanism, as will be described in more detail below. Cylinder lock  60  may further include an electronic locking mechanism comprising a motor, tumblers, sidebar, printed circuit board (including a micro-controller, and a wire connector for connecting the motor and PCB) to a reader box, as with the embodiment of the cylinder lock  20  shown in  FIG. 2  and described above. For simplifying the figures, however, the components for the electronic locking mechanism are omitted from the description of the second embodiment shown in  FIGS. 7-11 . 
       FIG. 8  shows a perspective view of the cylinder lock  60  with the cylinder housing  82 , collar  84 , and a return spring (described below) omitted from the figure. Cylinder lock  60  includes a cylinder  62  that is rotatable with respect to the housing  82  and comprises a cylinder plug (or plug)  63  rotationally disposed within the housing  82  with a longitudinal slot  64  (as described in the embodiment shown above), a shaft extension  66  that extends out of the housing  82  and to which the thumb-turn knob  22  is attached, a spring collar  68 , and a drive pin  70  attached to the shaft extension  66 . As with the embodiment described above, the lock  60  includes a cam  34 . 
     The shaft extension  66  extends through a slider  72  that comprises a cylinder structure having a back end  74  that is generally perpendicular to the longitudinal axis of the shaft extension  66  and a cam surface  78  that is formed at an acute angle relative to the longitudinal axis of the shaft extension  66 . In one embodiment, as shown in  FIG. 9 , the cam surface  78  lies within a single plane oriented at an angle of approximately 45 degrees to a longitudinal axis of the shaft extension  66 . A return spring  80  is disposed between the back end  74  of the slider  72  and the spring collar  68  extending radially from the shaft extension  66 . 
     The slider  76  is housed within the collar  84 . As shown in  FIGS. 12A-12C , the collar  84  has a cylindrical body  88  and attaching flanges  86  extending from the body  88  and with which the collar is secured to the cylinder housing  82  by means of mechanical fasteners, such as screws. The cylindrical body  88  defines a cylindrical interior portion, and the collar  84  has a partially closed front end  90  with a circular shaft opening  92  formed centrally therein. The shaft extension  66  extends through the opening  92 . The slider  72  includes anti-rotation ridges  76  (see, e.g.,  FIG. 8 ) preferably formed on diametrically-opposed sides of the slider  72 . The anti-rotation ridges  76  engage anti-rotation grooves  94  formed on the interior of the cylindrical body  88  of the collar  84 . Accordingly, the slider  72  is able to move in an axial direction relative to its cylindrical axis and the longitudinal axis of the shaft extension  66 , but is restricted from rotation about the longitudinal axis of the shaft extension  66 . The shaft extension  66 , on the other hand, is able to rotate about its longitudinal axis relative to the slider  72 . 
     The cylinder lock  60  includes a spring-biased cylinder return mechanism comprising the slider  72  interacting with a projection extending from a shaft extension  66  that is rotatable with the plug  63  such as a drive pin  70  attached to the shaft  66 . The knob  22  is attached to the shaft  66 , which may extend from the plug  63  or which may be an extension of the plug  63 . 
     The axial position of the slider  72  is biased outwardly, away from the housing  82 , by the return spring  80 . As the knob  22  and shaft  66  are rotated (thereby rotating the plug  63 ), the angled cam surface  78  of the slider  72  stays in constant contact with the drive pin  70  due to the outward spring force on the slider  72  by the return spring  80 . As noted, the cam surface  78  is preferably a flat surface oriented at an acute angle (e.g., 45 degrees) with respect to the longitudinal axis of the shaft  66 . Engagement of the drive pin  70  with the cam surface  78  translates rotational motion of the shaft  66  and cylinder plug  63  into axial translation of the slider  72 , or the engagement translates axial translation of the slider into rotational motion of the shaft  66  and cylinder plug  63 . The angled cam surface  78  of the slider  72  engages the drive pin  70  when the shaft  66  is rotated, and, in cooperation with the return spring  80 , causes the slider  72  to move axially forwards (towards the knob  22 ) or backwards (away from the knob  22 ) depending on the position of the drive pin  70  in the rotation of the shaft  66 . When the slider  72  is moved backwards away from the knob  22  the return spring  80  is compressed. 
     The spring  80  of the slider mechanism is in a relatively relaxed position when the drive pin  70  on the shaft  66  is at zero degrees rotation, as shown in  FIG. 9 . In the illustrated embodiment, zero degrees rotation corresponds to a top dead center position for the drive pin  70 . This also corresponds to the home, or locked, position of the plug  63 . When rotation of the shaft  66  begins in either direction (clockwise or counter clockwise), the drive pin  70  engaging the angled cam surface  78  of the slider  72  urges the slider  72  axially away from the knob  22 , and the return spring  80  is compressed, which results in increased elastic potential energy being stored in the return spring  80 . There is sufficient compressive force energy loaded onto the return spring  80  at any point beyond zero degrees of the shaft  66  for the angled cam surface  78  of the slider  72  to interact with the drive pin  70  on the shaft  66  and force rotation of the shaft  66  and plug  63  back to the zero degrees position when the user releases the thumb turn knob  22 . More specifically, with the drive pin  70  engaged with the top of the angled cam surface  78  of the slider  72 , at the zero degree rotation position as shown in  FIG. 9 , the slider  72  is at its closest axial position to the knob  22 , and the return spring  80  is at its least compressed position. On the other hand, as the shaft  66  rotates, the drive pin  70 , which has a fixed axial position on the shaft  66 , moves along the angled cam surface  78  and forces the slider  72  radially away from the knob  22 , thereby increasing the compression of the return spring  80 . At 90 degrees rotation of the knob  22  and shaft  66 , the drive pin  70  is at an intermediate position on the angled cam surface  78 , as shown in  FIG. 10 . When the drive pin  70  reaches the bottom of the angled cam surface  78  of the slider  72 , at the 180 degree rotation position, the slider  72  is at its furthest axial position relative to the knob  22 , and the return spring  80  is at its most compressed position (i.e., the position with the most potential energy), as shown in  FIG. 11 . When the knob  22  is released from any rotational position other than zero degrees, the return spring  80  will seek its position of least compression as potential energy is released by the return spring  80 , thereby forcing the slider  72  axially towards the knob  22 . As the slider  72  moves axially towards the knob  22 , the drive pin  70  will slide along the angled cam surface  78  toward the top end of the cam surface  78 , thereby rotating the shaft  66 , until the return spring  80  reaches its least compressed position. 
     Note that terms such as “top” or “bottom” in reference to the angled cam surface  78  of the slider  72  are non-limiting terms of convenience for describing the embodiment shown in the drawings. Persons of ordinary skill in the art will recognize that the slider  72  could be reoriented so that the “zero degree rotation position” corresponds to the bottom position of the angled cam surface  78  and the “180 degree rotation position” corresponds to the top of the angled cam surface  78 . 
     When the plug  63  is rotated back to the home position, the plug  63  is allowed to relock, and the cam  34  is returned to a position out of the way of the lockset mechanism. 
     The inventors have further noted that when the shaft and associated drive pin is rotated to a position exactly 180 degrees from the home position (i.e., to a “peak” of the angled cam surface), the pin is at a location of equilibrium such that there is an equalizing effect on the slider mechanism that may prevent the slider mechanism from rotating the shaft either clockwise or counter clockwise back to the home position. There is typically some spring force that can be relied upon that is provided from the lock mechanism to help overcome this condition. Such spring force can come from a spring latch lock set, such as shown in  FIG. 13 . 
     Two types of lockset in which cylinders according to the present invention may be incorporated include a “spring latch” lockset and a “dead latch” or dead bolt lockset. 
     In the spring latch lockset, the cylinder is merely required to momentarily pull in the latch to open the door. The locking mechanism has a spring loaded latch bolt with which the spring is compressed as the latch bolt is moved towards the unlocked position. Once the cam or tailpiece releases the spring latch bolt, it will attempt to “spring” back out into the locked position. This additional spring force inside the lockset will provide the cylinder with some assistance in returning to the home position until lockset disengages with the cam of the cylinder. In the spring latch application, a cylinder with 180 degree rotation limitation, such as the cylinder  20  shown in  FIGS. 2-6 , works fine. The cylinder return spring  32  can be installed such that it can work in either clockwise or counter clockwise directions up to the 180 degrees position. This is required because some doors are right handed and some doors are left handed relative to the hinges and lockset. 
     In a “dead latch” or dead bolt lockset, a cylinder that is limited to 180 degree rotation will not work. To operate the deadbolt function, the cam or tailpiece must be rotated up to, and beyond, 360 degrees to move the bolt from the locked to unlocked positions and vice versa. For this application the cylinder  60  shown in  FIGS. 7-12  is more suitable. 
     The cylinder lock  60  of  FIGS. 7-12  has other advantages. The cylinder lock  60  is configured to allow the cylinder plug  63  to be returned to the locked position from any rotational position relative to the locked position. In one embodiment, the cylinder lock  60  is also configured such that engagement of the drive pin  70  with the cam surface  78  causes the cylinder plug  63  to rotate either clockwise or counter clockwise toward the locked position on a path of least resistance to return the cylinder plug  63  to the locked position. In addition, the spring-biased cylinder plug return mechanism of the cylinder lock  60  is configured so that the cylinder plug  63  can be rotated from the locked position beyond 360 degrees in either direction necessary to drive a lock mechanism and the cylinder plug  63  will still return to the locked position when the knob  22  is released by the user. 
     While the present invention has been described and shown in considerable detail with reference to certain illustrative embodiments, including various combinations and sub-combinations of features, those skilled in the art will readily appreciate other embodiments and variations and modifications thereof as encompassed within the scope of the present invention. Moreover, the descriptions of such embodiments, combinations, and sub-combinations is not intended to convey that the inventions requires features or combinations of features other than those expressly recited in the claims. Accordingly, the present invention is deemed to include all modifications and variations encompassed within the spirit and scope of the following appended claims.