Patent Publication Number: US-10316548-B2

Title: Actuator assembly for locking devices

Description:
FIELD OF INVENTION 
     The present invention relates to locking devices, in particular to an actuator assembly for a locking device with electronic control. 
     BACKGROUND OF INVENTION 
     1. Description of the Related Art 
     Conventional locking device with an electronic control generally adopts a locking assembly driven by a micro DC motor, and one of the technical solutions uses a coil spring sheathed on a shaft and a pin fixed to the shaft to convert a rotational motion of the motor into a linear motion between the spring and the pin, so as to push or pull a blocking element for controlling a lock bolt to retract. 
     As to the solution of using the rotation of the pin, when the pin moves spirally along the spring, the spring is compressed by the pressure of the pin, so that a larger friction is produced, and a rotational force of the spring and the shaft is produced by the friction, so that the spring may be rotated together with the shaft and jittered radially, and the spring cannot be displaced stably in the axial direction, and thus not just resulting the wear-out or damage between the spring and the sliding block only, but also failing to allow the pin to enter into the spiral track of the spring successfully. In addition, the friction between the pin and the spring may also wear out the pin and the spring. As disclosed in P.R.C. Pat. No. CN201110244325.0, a pin is rotated to push a pin to push the spring to displace axially, so as to push a blocking element to be stretched out or retracted. To overcome the unintentional rotation and jitter of the spring, a third winding of the spring is provided to absorb and buffer the vibrations and impacts of the pin exerted to the pin and produced when the motor is turned on and rotated, so as to prevent the spring from being twisted, deformed, or shaken. 
     Alternatively, the coil spring is fixed onto the drive shaft of the motor and rotated together with the motor, and the pin is fixed to an axially slidable blocking element in order to achieve the effect of pushing or pulling the blocking element into a locked position or an unlocked position. As disclosed in U.S. Pat. No. 5,628,216 issued to Schlage Lock Company, a locking device is installed to a door lock and comprises a motor, a gear set coupled to the motor, a guiding shaft coupled to the gear set, a coil spring fixed to a free end of a cylinder of the guiding shaft and partially stretched coaxially into a bushing of a plug, and a pin perpendicularly installed to the bushing of the plug while passing through two adjacent rounds of the spring of the bushing of the plug. The motor drives the coil spring to rotate, and the pin is rotated into the two adjacent rounds of the coil spring, so that the bushing of the plug slides along the axis of the motor shaft and between a locked position and an unlocked position to control locking and unlocking the door lock. 
     Another patent further discloses a locking device of a door lock, and the difference between this patent and the aforementioned patent resides on that the pin of this patent is installed to a frame of a protrusion formed at an end of a locking plate, and a coil spring is passed through from the interior of the frame, and the pin is inserted between two adjacent rounds of the spring, and the locking plate is shifted axially between the locked position and the unlocked position under the precession effect of the spring and the pin. 
     The technical solutions provided by the foregoing patented technology have the following advantages. Since the spring and the drive shaft are fixed, the inertia of the rotation is small, and there is no issue on the rotation and radial shaking of the spring. However, there is still an unsatisfactory result. For example, the load (including the bushing of the plug and the locking plate) has relatively larger volume and weight, so that when the spring is rotated into the pin, the spring is pulled and stretched, and the friction in contact with the pin is increased, and the spring and pin may be worn out or damaged easily. 
     In addition, some actuator assemblies require a spring with a fixed end and a non-fixed longer end, so that when a portion of the actuator assembly away from the drive shaft is rotated, there is no radial limitation, and a swinging deviated from the axis may be produced to cause vibrations of the spring. 
     Obviously, the technical solution of ‘converting the rotational motion of the motor into the linear motion between the coil spring and the pin for the interaction of the pin and coil in order to push or pull a blocking element for controlling a locking device’ requires further improvements. 
     2. Summary of the Invention 
     Therefore, it is a primary objective of the present invention to provide an actuator assembly for a locking device, and the actuator assembly is capable of preventing the vibration produced by the rotation of the spring and reducing the friction between the pin and the spring. 
     To achieve the aforementioned and other objectives, the present invention provides an actuator assembly for a locking device with electronic control, comprising: a motor, having a drive shaft installed to a motor shaft, and a coil spring installed to the drive shaft, characterized in that the actuator assembly further comprises: a follower shaft capable of displacing in an axial direction in the coil spring, and a pin installed onto the follower shaft and rotatable into the coil spring, and the follower shaft is extended into the coil spring and slidably fitted to the coil spring. 
     Wherein, the coil spring is a cylinder spring comprising a rotating-in portion and a buffering portion, and the pin displaces axially within a range of the rotating-in portion. 
     Wherein, the buffering portion has a plurality of tightly wound windings with a pitch equal to zero, and the rotating-in portion has a pitch greater than the diameter of the pin. 
     Wherein, the external diameter of the follower shaft and the internal diameter of the cylinder spring have a unilateral gap of 0.15 mm˜0.30 mm, and the rotating-in portion has a pitch equal to 1.1˜1.3 times of the diameter of the pin. 
     Wherein, the cylinder spring has a first fixing ring and a second fixing ring installed at two free ends of the cylinder spring respectively, a first U-shaped bend coupled to the first fixing ring, and a second U-shaped bend coupled to the second fixing ring; the drive shaft has a ring-shaped protruding strip formed thereon, and the ring-shaped protruding strip comprises a protruding strip head matched with the first U-shaped bend, and the first U-shaped bend is sheathed on the protruding strip head, and the first fixing ring is installed to the outer side of the ring-shaped protruding strip. 
     Wherein, the follower shaft has a cylindroid disposed at an end of the follower shaft and protruded out from the outer peripheral surface of the follower shaft. 
     Wherein, the drive shaft includes a first shaft shoulder and a second shaft shoulder, a fixing frame installed between the drive shaft and the motor housing, and the fixing frame includes two fixing rods fixed to the motor housing and a third U-shaped bend perpendicular to the fixing rod, and the third U-shaped bend is disposed between the first shaft shoulder and the second shaft shoulder for limiting the axial displacement of the drive shaft. 
     Wherein, the fixing frame is formed by bending a steel wire, and the third U-shaped bend has a diameter smaller than the first shaft shoulder and greater than the second shaft shoulder. 
     Wherein, the motor shaft is a flat shaft, and the drive shaft includes a flat shaft hole matched with the flat shaft. 
     Wherein, the follower shaft includes a pin hole, and the pin has a head disposed between two adjacent rounds of the coil spring and a tail fixed to the pin hole. 
     In summation, the present invention has the following advantageous effects: 
     1. Compared with the prior art, the follower shaft of the present invention effectively maintains a radial limitation of the cylinder spring to overcome the vibration of the spring occurred during the rotation of the cylinder spring and the axial displacement of the follower shaft. 
     2. The cylinder spring of the present invention has the structure of the buffering portion, and when the pin displaces axially with respect to the cylinder spring, the buffering portion is also pulled and stretched, so that the rotating-in portion of the spring is pulled and stretched and the compression is reduced to effectively reduce the friction between the pin and the spring, so as to minimize the wear-out and damage of components. 
     3. The actuator assembly for the locking device in accordance with the present invention has the features of small number of components, simple structure, and easy manufacture and installation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a preferred embodiment of the present invention; 
         FIG. 2  is an exploded view of a preferred embodiment of the present invention; 
         FIG. 3  is a perspective view of a cylinder spring of a preferred embodiment of the present invention; 
         FIG. 4  is a perspective view of a drive shaft of a preferred embodiment of the present invention; 
         FIG. 5  is another perspective view of a drive shaft of a preferred embodiment of the present invention; 
         FIG. 6  is a perspective view of a follower shaft of a preferred embodiment of the present invention; 
         FIG. 7  is a schematic view of a dial lever installed at a panel device being situated in a locked position in accordance with a preferred embodiment of the present invention; and 
         FIG. 8  is a perspective view of a dial lever installed at a panel device being situated in an unlocked position in accordance with a preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The above and other objects, features and advantages of this disclosure will become apparent from the following detailed description taken with the accompanying drawings. 
     With reference to  FIGS. 1 and 2  for an actuator assembly in accordance with a preferred embodiment of the present invention, the actuator assembly comprises a motor  10 , a drive shaft  30 , a cylinder spring  20 , a follower shaft  40 , and a pin  60 . The motor  10  is a general DC motor, and the drive shaft  30  and the motor shaft  11  are flat shafts in coordination with the torque of transmission, and the motor shaft  11  and the shaft hole  35  of the drive shaft are interference fitted and fixed. The two free ends of the cylinder spring  20  are configured in 1˜2 rounds of first fixing ring  21  and second fixing ring  22 , and the first fixing ring  21  and the second fixing ring  22  are a first U-shaped bend  23  and a second U-shaped bend  24  coupled to each other in opposite directions and having the same shape, and the drive shaft  30  has a non-closed ring-shaped protruding strip  31 , and the ring-shaped protruding strip  31  includes two protruding strip heads  32 , and one of the protruding strip head is matched with the first U-shaped bend  23 , and the first U-shaped bend  23  is embedded precisely into one of the protruding strip heads  32 , and the first fixing ring  21  is sheathed on the outer side of the protruding strip head  32 , and the axial displacement of the cylinder spring  20  is limited by the ring-shaped protruding strip  31 , and the radial displacement of the cylinder spring  20  with respect to the drive shaft  30  is limited by the first U-shaped bend  23  and the protruding strip head  32 . The pin  60  may be installed on the follower shaft  40  by stretching the two pin heads symmetrically out from the external periphery of the follower shaft  40 , or stretching a pin head in a single direction, depending on the object driven by the actuator assembly. In this preferred embodiment, the object driven by the present invention is a rotatable dial lever  50  disposed under the follower shaft  40 , so that it is not necessary to have two pin heads as long as a pin head  61  of the pin  60  is installed into a chute  55  of a dial lever  50 . When the pin  60  displaces linearly, the pin head  61  is acted to the chute  55  to push the dial lever  50  to rotate. A pin tail  62  has a diameter greater than the diameter of the pin head  61 , and interference fitted with the pin hole  41 , so that the external periphery of the pin tail  62  has a knurling. When the motor  10  drives the cylinder spring  20  to rotate, the pin  60  is limited by the chute  55  and will not be moved with the cylinder spring  20 , and the pin  60  can be displaced in an axial direction along the cylinder spring  20  (as shown in  FIGS. 6 and 7 ). 
     With reference to  FIG. 3  for the structure of the cylinder spring  20 , the cylinder spring  20  includes a rotating-in portion  25  with a relatively larger pitch and capable of being rotated into the pin  60  and a buffering portion  26  having a plurality of tightly wound windings with a pitch approaching zero, and the rotating-in portion has approximately 15˜17 rounds, and the pitch is 1.1˜1.3 times of the diameter of the pin  60 , and the buffering portion  26  is wound tightly with 7˜9 rounds. The tightly section provides an effect of buffering the pushing force of the pin  60  exerted to the rotating-in portion  25 , and the pushing force pulls and stretches the rotating-in portion  25 . After such section of the buffering portion  26  is wound tightly, and the rotating-in portion  25  receives the tensile force, the buffering portion  26  is also pulled and stretched. Provided that the total stretch of the spring remains unchanged, the pulling/stretching force of each round of the spring is reduced, so that the pulling/stretching force exerted onto the rotating-in portion  25  is reduce, so as to decrease the friction between the cylinder spring  20  and the pin  60  and minimize the wear-out or damage of the cylinder spring  20  and the pin  60 . 
     With reference to  FIGS. 4, 5 and 6  for a drive shaft  30  and a follower shaft  40  of the invention, the drive shaft  30  includes a first shaft shoulder  34  adjacent to the motor  10 , a second shaft shoulder  37  disposed adjacent to the first shaft shoulder  34 , a shaft neck  33  disposed adjacent to the second shaft shoulder  37 , a ring-shaped protruding strip  31  disposed adjacent to the shaft neck  33 , and a shaft extension  36  disposed adjacent to the ring-shaped protruding strip  31 . The first fixing ring  21  of the cylinder spring  20  is sheathed on the shaft neck  33 , and the first U-shaped bend  23  is latched to the protruding strip head  32 , and the tightly wound buffering portion  26  has a several rounds sheathed on the shaft extension. The pin hole  41  is formed at an end of the follower shaft  40  proximate to motor shaft  11 . After the follower shaft  40  is installed in the cylinder spring  20 , the pin hole  41  is disposed precisely at the center position of the rotating-in portion  25 . 
     In  FIGS. 7 and 8 , the follower shaft  40  has a length greater than the length of the cylinder spring  20 . When the follower shaft  40  is situated at a sliding-in position, the follower shaft  40  keeps stretching to the buffering portion  26 . When the follower shaft  40  is situated at a sliding-out position, half of the rotating-in portion  25  is still sheathed on the follower shaft  40 . During the process of rotating the cylinder spring  20  and displacing the follower shaft  40  axially, the follower shaft  40  maintains the radial limitation of the cylinder spring  20 . The follower shaft  40  has a diameter slightly smaller than the diameter of the internal periphery of the cylinder spring, so that the unilateral gap between the follower shaft  40  and the cylinder spring will not affect the slide fit in the axial direction, and preferably the deviation is minimized when the cylinder spring is rotated. In this preferred embodiment, the unilateral gap has a numerical range of 0.15 mm˜0.30 mm. 
     The slidably fitted end of the follower shaft  40  and the locking device has two symmetrical protruding cylindroid  42 , and the rail matched with the two cylindroids  42  is composed of an upper rail  75  of the panel  1  (as shown in  FIG. 7 ) and a lower rail (not shown in the figure) of the bottom plate, and the upper rail  75  has two recessions formed on the two parallel rectangular strips for exactly receiving the cylindroid  42 , and the lower rail is composed of two rectangular strips (not shown in the figure) and two protrusions concavely recessed and disposed opposite to each other, after the panel  1  and the bottom plate are assembled, the cylindroid  42  is disposed between the upper rail  75  and the lower rail, and a slidably fitted gap is maintained between the cylindroid  42  and the rails. The drive shaft  30  and the follower shaft  40  may be made of metal or engineering plastics. In this preferred embodiment, nylon is adopted. To reduce the weight, the follower shaft  40  comes with a hollow structure. 
     With reference to  FIGS. 7 and 8  for a panel device of a mechanical locking button in accordance with a preferred embodiment of the present invention, the panel device includes a panel  1  installed onto a suitcase cover, a bottom plate (not shown in the figure) matched with the panel  1 , a button  2  installed onto the panel  1 , a dial lever  50  installed under the stroke of the button  2  for controlling whether or not the button  2  can be pressed, and the actuator assembly of the present invention is installed on a side of the button  2 . The dial lever  50  includes a hub  51 , and the hub  51  has a pivot  53 , and a pivot hole (not shown in the figure) matched with the pivot and formed between the panel  1  and the bottom plate, and the dial lever  50  may be rotated around the pivot hole, and an arm  54  extended out from the hub  51 , and the arm  54  has a chute  55  installable into the pin head  61 , and the hub  51  has three first teeth  56  and three adjacent first grooves  57 , and the first protrusion  17  formed the inner plane of the button  2  may enter into of the first groove  57 . When the dial lever is situated at a first angle, the three first teeth  56  and the three first protrusions  17  are opposite to each other. Now, the downward stroke of the button  2  is blocked by the first teeth  56  of the dial lever  50 , so that the button  2  cannot be pressed down. When the dial lever  50  is pushed by the pin head  61  to a second angle, the first groove  57  and the first protrusion  17  are opposite to each other, and the downward stroke of the button  2  is not blocked. When the button  2  is pressed, the first protrusion  17  enters into the first groove  57 . Since a longer arm is installed between the pin  60  and the pivot  53 , the pin  60  can push the dial lever  50  to rotate by a small force in order to lock and unlock the button  2 . The panel  1  further has a first position switch  71 , and an end of the arm  54  touches the first position switch  71  at a predetermined angle, and the position of the dial lever  50  is transmitted to a control unit of the locking device. 
     In  FIG. 7 , the locking device is situated at the locked position, and the rotating-in portion  25  and buffering portion  26  of the cylinder spring are pulled and stretched, and the first tooth  56  of the dial lever  50  and the first protrusion  17  of the button  2  abut each other to block pressing the button  2  (wherein the button  2  is pressed in a direction from the surface as shown in  FIGS. 6 and 7 ). After the unlock authorization is received, the motor  10  drives the cylinder spring  20  to rotate, and the pushing force produced by rotating the follower shaft  40  by the pin  60  into the cylinder spring  20  slides from the locked position axially to the unlocked position, and the pin  60  is acted to the chute  55  to push the dial lever  50  to rotate an angle, and the first tooth  56  of the dial lever  50  is detached from the abutment of the first protrusion  17 . In the process of rotating the first groove  57  to reach a position opposite to the first protrusion  17 , the pin  60  is displaced to the left side of the cylinder spring  20  round by round, and the pulling/stretching force is decreased gradually. Now, an end of an arm  54  has touched the first position switch  71  (as shown in  FIG. 8 ). Now, the button  2  is pressed, and there is no blocking, so that the suitcase can be opened after the button  2  is pressed. After the external force pressing at the button  2  is released, a restoring spring (not shown in the figure) resets the button  2 . After the button  2  is reset, if the control unit of the locking device sends out a locking signal, the motor  10  will be rotated in the reverse direction, and the cylinder spring  20  starts displacing towards the left side of the pin  60  round by round. In the meantime, the pulling/stretching force is increased gradually until the pin  60  pushes the dial lever  3  back to the locked position to resume blocking the button  2 . 
     In the structure of a fixing frame  65  as shown in  FIGS. 1 and 2 , a fixing frame  65  is installed between the drive shaft  30  and the motor  10  to prevent the drive shaft  30  from being displaced axially or separated from the motor shaft. The fixing frame  65  is formed by bending a slightly thick steel wire, and the third U-shaped bend  66  perpendicular to the drive shaft  30  has a diameter smaller than the first shaft shoulder  34  and greater than second shaft shoulder  37 , and is disposed on an inner side of the second shaft shoulder  37 , and two symmetrical free ends of the third U-shaped bend  66  and the third U-shaped bend  66  form a right angle, so that a pair of fixing rods  67  are pressed under the housing of the motor  10 . After the motor  10  is fixed by the panel  1  and the bottom plate, the fixing frame  65  is then fixed. In normal conditions, the third U-shaped bend  66  is not in contact with the second shaft shoulder  37  and any part of the drive shaft  40 . When the drive shaft  30  is displaced towards the cylinder spring  20 , the U-shaped bend is contacted with the second shaft shoulder  37  to stop the drive shaft  30  to continue its axial displacement. To achieve a reliable effect, a pair of L-shaped protrusions  77  are installed at a position of the panel  1  corresponding to the shaft neck  33  to block the inner side of the third U-shaped bend  66 . When the fixing frame  65  is pushed inwardly, the L-shaped protrusion  77  has the effect of supporting the fixing frame  65 . 
     While the invention has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.