Patent Publication Number: US-2010122561-A1

Title: Driving device for an electric lock latch

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a driving device for an electric lock latch, and more particularly to a structure with a drive shaft having a threaded portion for driving a spiral spring in threaded connection thereto. Moreover, the lock latch is connected at the external part of the spiral spring. As a result, the circular motion of the drive shaft is converted into the rectilinear motion of the spiral spring such that the lock latch is moved. In this way, the locked and unlocked state of the lock device may be changed by the movement of the lock latch. Moreover, the structure of the invention can be applied to all kinds of lock devices. 
     2. Description of the Related Art 
     It is quite normal that the lock employs an electromagnetic valve to control the movement of the latch, thereby changing the locked or unlocked state. Such a structure is disclosed in the U.S. Pat. No. 6,082,791. However, the activation of the electromagnetic valve requires a large power consumption. Therefore, it is necessary to provide an external power source and a control unit for the electric lock latch using the electromagnetic valve. As a result, the installer must have the electronic knowledge and the installation skill, thereby causing much difficulty for the installer. 
     In order to move the lock latch via the electromagnetic valve, a motor may be used to impart a motion to the lock latch. U.S. Pat. No. 5,697,798 “MOTORIZED LOCK ACTUATORS”, U.S. Pat. No. 5,628,216 “LOCKING DEVICE” and U.S. Pat. No. No. 6,076,870 belong to such a structure. “Motorized electric strike” disclosed in U.S. Pat. No. 6,076,870 relates to an electric strike with a pivoting locking member for locking an electric strike in the closed position. The locking member is pivoted between the locked and unlocked positions by a low current motor. A drive pin pivotally engages the locking member. The motor rotates a roll pin threadably engaging the coil faces of a spring mounted to the drive pin. Rotation of the motor compresses or expands the spring to axially move the drive pin and thereby pivot the locking member between the locked and unlocked positions. 
     However, the structure according to the U.S. Pat. No. 6,076,870 employs a motor to impart a rotary motion to the roll pin, thereby biasing the spring in a retracted or extended position. In this way, the drive pin is axially moved to bring the locking member between the locked and unlocked positions. The spring is equidimensionally formed. The time to supply power to the motor must be exactly controlled to prevent the breakdown of the spring due to over-compression or over-extension when the spring is moved by the rotation of the roll pin. Moreover, the installation of the roll pin and the drive pin according to the U.S. Pat. No. 6,076,870 is complicated. Therefore, a further improvement is required. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to eliminate the above-mentioned drawbacks of the conventional equidimensional spring activated by a pin and to provide a driving device for an electric lock latch wherein the middle part of the spiral spring is constructed as the threaded joint portion having a smaller diameter in threaded connection to the threaded portion of the drive shaft. Moreover, the internal and external parts of the spiral spring have a larger diameter such that no threaded connection to the drive shaft is established. In other words, the drive shaft will be idly rotated at the internal and external parts of the spiral spring. As a result, the spring may be protected from damage due to over-compression or over-extension. 
     Another object of the invention is to provide a driving device for an electric lock latch that can be easily modularized and applied to all kinds of lock devices. Accordingly, the lock structure and the installation thereof may be simplified. 
     In order to achieve the above-mentioned objects, the invention includes: 
     a) a housing; 
     b) a motor positioned within the housing with a power output shaft secured to a drive shaft with a threaded portion; 
     c) a spiral spring having an internal part fixed in the housing or at the motor, the middle part of the spiral spring having a threaded joint portion (with a smaller diameter) corresponding to the threaded portion of the drive shaft, the internal and external parts of the spiral spring not having the threaded connection to the threaded portion of the drive shaft; and 
     d) a lock latch secured to the external part of the spiral spring. 
     Based upon the above-mentioned features, the housing includes a guide slot corresponding to the spiral spring, and lock latch includes an insertion portion fitting into the external part of the spiral spring, thereby creating a reliable connection between the lock latch and the spiral spring, and wherein a tail loop is formed at the external end of the spiral spring, and wherein a connection element passes through the tail loop for connecting the spiral spring to the lock latch. It is also possible that the lock latch includes a mounting sleeve fitting over the external part of the spiral spring, thereby creating a reliable connection between the lock latch and the spiral spring, and wherein a tail loop is formed at the external end of the spiral spring, and wherein a connection element passes through the mounting sleeve and the tail loop for connecting the spiral spring to the lock latch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accomplishment of this and other objects of the invention will become apparent from the following descriptions and its accompanying figures of which: 
         FIG. 1  is an exploded perspective view of a first embodiment of a driving device in accordance with the invention; 
         FIG. 2  is an perspective assembly view of the first embodiment of a driving device in accordance with the invention; 
         FIG. 3  is a cross-sectional view of the first embodiment of the structure of  FIG. 2  with the lock latch in an extended position; 
         FIG. 4  is a cross-sectional view of the first embodiment of the structure of  FIG. 2  with the lock latch in a retracted position; 
         FIG. 5  is an exploded perspective view of the full structure of the first embodiment of the invention applied to a cylinder lock; 
         FIG. 6  is an exploded perspective view of the partial structure of the first embodiment of the invention applied to a cylinder lock; 
         FIG. 7  is an perspective assembly view of a second embodiment of a driving device in accordance with the invention; 
         FIG. 8  is a cross-sectional view taken along with the line  8 - 8  of  FIG. 7 ; 
         FIG. 9  is an schematic drawing of the second embodiment of the invention applied to a first type mortise lock; and 
         FIG. 10  is an schematic drawing of the second embodiment of the invention applied to a second type mortise lock. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     First of all, referring to  FIGS. 1 and 2 , a first embodiment of the structure in accordance with the invention includes a housing  10   a,  a motor  20 , a spiral spring  30 , and a lock latch  40   a.    
     The motor  20  is positioned within the housing  10   a  with a power output shaft secured to a drive shaft  22  with a threaded portion  21 . 
     The spiral spring  30  includes an internal part fixed in the housing  10   a  or at the motor  20 . The middle part of the spiral spring  30  includes a threaded joint portion  32  (with a smaller diameter) corresponding to the threaded portion  21  of the drive shaft  22 . The internal and external parts of the spiral spring  30  do not have the threaded connection to the threaded portion  21  of the drive shaft  22 . The housing  10   a  further includes a guide slot  11   a  corresponding to the spiral spring  30 . 
     The lock latch  40   a  is secured to the external part of the spiral spring  30 . The lock latch  40   a  includes an insertion portion  41  fitting into the external part of the spiral spring  30 , thereby creating a reliable connection between the lock latch  40   a  and the spiral spring  30 . A tail loop  31  is formed at the external end of the spiral spring  30 . Moreover, a connection element  42  such as screw passes through the tail loop  31  for connecting the spiral spring  30  to the lock latch  40   a.    
     Based on the above-mentioned structure, the operation of the first embodiment of the invention is shown in  FIGS. 3 and 4 . When the motor  20  provides a driving power, the power will be transmitted through the threaded portion  21  of the drive shaft  22  to the threaded joint portion  32  of the spiral spring  30 . The internal part is fixed in the housing  10   a  or at the motor  20 . Therefore, the circular motion of the drive shaft  22  is converted into the rectilinear motion of the spiral spring  30 . In other words, the spiral spring  30  is compressed in such a manner that the lock latch  40   a  secured to the external part of the spiral spring  30  is moved at the same time. Moreover, the guide slot  11   a  of the housing  10   a  ensures a smooth movement of the spiral spring  30  without departing from the prearranged path. In this way, the lock latch  40   a  may be moved to switch the lock in a locked or unlocked state. 
     The structure in accordance with the first embodiment of the invention may be applied to a cylinder lock disclosed in the US2007/0182169A1 (see  FIGS. 5 and 6 ). The cylinder lock employs a drive unit  51  to activate the door latch  52 . The activation is done (by the drive unit  51 ) through the rotation of an internal drive tube  53  or an external drive tube  54 . The internal drive tube  53  is coupled with an internal door handle  55  while an external sleeve  56  slips over the external drive tube  54 . Moreover, the external sleeve  56  is coupled to an external door handle  57 . The structure in accordance with the invention is installed within the internal drive tube  53  in such a manner that the lock latch  40   a  is directed to the external drive tube  54  and the external sleeve  56 . The external sleeve  56  includes an axial clip-stop indentation  561  corresponding to the lock latch  40   a.  The external drive tube  54  includes an axial movement indentation  541  and a toroidal idle-rotation indentation  542 . When the motor  20  gives out rotary power, the lock latch  40   a  will be moved within the axial clip-stop indentation  561  of the external sleeve  56 . When the lock latch  40   a  is located in the toroidal idle-rotation indentation  542  of the external drive tube  54 , the external sleeve  56  is rotated without the load of the external drive tube  54 . In other words, the lock latch  40   a  can&#39;t rotate the external drive tube  54  to create an unlocked state. When the lock latch  40   a  is located in the axial movement indentation  541  of the external drive tube  54 , the external sleeve  56  may impart a rotary motion to the external drive tube  54  by means of the lock latch  40   a.  In this way, the drive unit  51  may be activated by a convex ear  543 . Thereafter, the door latch  52  may be driven by the drive unit  51  to unlock the door. 
     Referring to  FIGS. 7 and 8 , a second embodiment of the structure in accordance with the invention includes a housing  10   b,  a motor  20 , a spiral spring  30 , and a lock latch  40   b.    
     The motor  20  is positioned within the housing  10   b  with a power output shaft secured to a drive shaft  22  with a threaded portion  21 . 
     The spiral spring  30  includes an internal part fixed in the housing  10   a  or at the motor  20 . The middle part of the spiral spring  30  includes a threaded joint portion  32  (with a smaller diameter) corresponding to the threaded portion  21  of the drive shaft  22 . The internal and external parts of the spiral spring  30  do not have the threaded connection to the threaded portion  21  of the drive shaft  22 . The housing  10   b  further includes a guide slot  11   b  corresponding to the spiral spring  30 . 
     The lock latch  40   b  is secured to the external part of the spiral spring  30 . The lock latch  40   b  includes an mounting sleeve  43  fitting over the external part of the spiral spring  30 , thereby creating a reliable connection between the lock latch  40   b  and the spiral spring  30 . A tail loop  31  is formed at the external end of the spiral spring  30 . Moreover, a connection element  42  passes through the mounting sleeve  43  and the tail loop  31  for connecting the spiral spring  30  to the lock latch  40   b.    
     The structure in accordance with the second embodiment of the invention may be applied to a first type mortise lock (direct control locking element) and a second type mortise lock (indirect control locking element) (see  FIGS. 9 and 10 ). The cylinder lock employs a drive unit  51  to activate the door latch  52 . The structure of the invention has various applications that are not detailed hereinafter. In addition, they are not the object of the invention so that no further descriptions thereto are given hereinafter. 
     In summary, the drive shaft  22  having the threaded portion  21  is employed to drive the spiral spring  30  in threaded connection thereto. Moreover, the lock latch  40   a,    40   b  is connected at the external part of the spiral spring  30 . As a result, the circular motion of the drive shaft  22  is converted into the rectilinear motion of the spiral spring  30  such that the lock latch  40   a,    40   b  is moved. In this way, the locked and unlocked state of the lock device may be changed by the movement of the lock latch  40   a,    40   b.  The middle part of the spiral spring  30  is constructed as the threaded joint portion  32  having a smaller diameter. Moreover, the internal and external parts of the spiral spring have a larger diameter such that no threaded connection to the drive shaft is established. In other words, the drive shaft  22  will be idly rotated at the internal and external parts of the spiral spring  30 . The movement position of the lock latch  40   a,    40   b  may be controlled by the length of the threaded joint portion  32 . As a result, it is not necessary to exactly control the duration of the power supply to the motor. In addition, the spring may be protected from damage due to over-compression or over-extension. Consequently, the motor  20  of the invention may activate the lock latch  40   a,    40   b  with a slight power consumption to change its position. That is, the battery can supply the power needed. It is not necessary to connect to the mains. The structure and the assembly are both very simple. Accordingly, the lock structure and the installation thereof can be simplified.