Patent Publication Number: US-6705138-B1

Title: Clutch mechanism for a lock

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a clutch mechanism for a lock. In particular, the present invention relates to a clutch mechanism for a lock that allows the outer handle to rotate freely when the lock is in a locked state so that the internal parts of the lock will not be damaged. 
     2. Description of the Related Art 
     A conventional door lock generally includes an outer handle and an inner handle respectively attached to the outside and the inside of a door so that the latch bolt can be retracted by turning either one of the outer handle and the inner handle. When in a locked state, the outer handle could not be turned for retracting the latch bolt. It is, however, not uncommon that the user still applies force to the outer handle to an extent that is normally sufficiently large enough for retracting the latch bolt if the user is not aware of the locked state of the lock. Thus, the inner parts of the lock connected to the handle could be damaged by a torque resulting from the force applied to the outer handle. The situation worsens for a lock with lever type handles. 
     U.S. Pat. No. 6,041,630 discloses a lock having a clutch mechanism to solve this problem. The lock includes an inner handle having a locking bar received therein and an outer handle connected to a spindle with a retaining base received therein which has two first grooves defined therein. A cam is connected to the retaining base and has two second grooves which communicate with the first grooves so that a locking piece is movably received between the retaining base and the cam with a spring biased between the locking piece and the retaining base. The locking piece has two flanges movably received in the first grooves and the second grooves. A slide is movably received in the cam and contact the locking piece at one end thereof and the locking bar at the other end thereof so that the two flanges of the locking piece are disengaged from the second grooves when the locking bar is pushed. Therefore, the outer handle can be freely rotated. Nevertheless, there are too many elements for the clutch mechanism. The assembly procedure is too complicated and the overall cost is increased. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a clutch mechanism for a lock that allows easy assembly and that is easy to manufacture while allowing the outer handle to rotate freely when the lock is in a locked state so that the internal parts of the lock will not be damaged. 
     A lock mechanism in accordance with the present invention comprises: 
     a latch; 
     a retractor for retracting the latch; 
     an inside handle; 
     an inside spindle having a first end fixed to the inside handle to turn therewith and a second end, the inside spindle being operably connected to the retractor such that rotation of the inside spindle causes retraction of the latch; 
     a locking bar extending through the inside spindle and having a first end and a second end; 
     an inside hub for rotatably receiving the second end of the inside spindle; 
     an outside handle; 
     an outside spindle having a first end and a second end fixed to the outside handle to turn therewith, the first end of the outside spindle including a slot extending along a longitudinal direction of the outside spindle; 
     an outside hub for rotatably receiving the first end of the outside spindle; 
     a cam received in the first end of the outside spindle, the cam being movable relative to the outside spindle along a longitudinal direction of the outside spindle, the cam having an engaging notch, the cam further having an ear projecting outward therefrom, the ear of the cam being releasably engaged with the retractor such that rotation of the cam causes retraction of the latch; 
     a sleeve received in the cam and having a first end and a second end; 
     a lug having an arm and a ring formed on an end of the arm, the ring being so mounted to the first end of the sleeve that the sleeve is not turned when the arm is turned and that the arm and the sleeve are jointly movable along the longitudinal direction of the outside spindle, the arm extending through the engaging notch of the cam and the slot of the outside spindle, the cam and the outside spindle being turned jointly when the outside handle is turned; and 
     an elastic element mounted between the outside handle and the cam for biasing the ear of the cam to engage with the retractor; 
     wherein when the locking bar is moved to a locking position, the lug and the sleeve are moved away from the retractor, the cam is also moved away from the retractor such that the ear of the cam is disengaged from the retractor, allowing free rotation of the outside handle without causing retraction of the latch. 
    
    
     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a lock in accordance with the present invention. 
     FIG. 2 is a sectional view of the lock in accordance with the present invention, wherein the lock is in an unlocked state. 
     FIG. 3 is an exploded perspective view of a clutch mechanism of the lock in accordance with the present invention. 
     FIG. 4 is a sectional view similar to FIG. 2, wherein the lock is in a locked state. 
     FIG. 5 is a sectional view taken along plane  5 — 5  in FIG. 4, illustrating free rotation of the outer handle when the lock is in the locked state. 
     FIG. 6 is a sectional view similar to FIG. 4, illustrating unlocking operation by a key. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a lock in accordance with the present invention generally comprises an inside handle assembly  1 , an inside spindle  2 , an outside handle assembly  3 , an outside transmission assembly  4 , and a latch mechanism  5 . 
     The inside handle assembly  1  includes an inside handle (e.g., a lever  11 ) and an inside rose assembly  12  mounted to an end of the inside lever  11 . The inside spindle  2  is mounted to an inside hub  13  that is mounted to an inner side of the inside rose assembly  12 . The outside handle assembly  3  includes an outside handle (e.g., a lever  31 ) and an outside rose assembly  32  mounted to an end of the outside lever  31 . The outside transmission assembly  4  is mounted to an outside hub  33  that is mounted to an inner side of the outside rose assembly  32 . The outside hub  33  and the inside hub  13  are connected together by fasteners  60 . A locking bar  14  extends through the inside spindle  2  and is movable along a longitudinal direction of the inside spindle  2 . A push button  15  is attached to an end of the locking bar  14  and exposed outside the inside lever  11 , as shown in FIG.  4 . 
     A cylinder  34  is mounted in a shank  310  of the outer lever  31  and has a cylinder bar  341  protruding therefrom. A seat  35  is securely mounted in the outside hub  33  for positioning the outer transmission assembly  4 . The latch mechanism  5  is mounted in the outside hub  33  and operably connected to the inner spindle  2  and the outer transmission assembly  4 . The latch mechanism  5  includes a latch  51  that extends out of the outside hub  33  via a notch  331  of the outside hub  33 . The latch  51  is retactable by a retractor  52 , and a catch  53  is movably received in the retractor  52 . 
     Referring to FIGS. 2 and 3, the outer transmission assembly  4  includes an outside spindle  41  having a first end received in the outside hub  33  and a second end fixed to the outside lever  31  to turn therewith. The outer transmission assembly  4  further includes a cam  42  received in the first end of the outer spindle  41 , a sleeve  43  received in the cam  42 , and a lug  44 . 
     The first end of the outside spindle  41  includes a slot  411  defined in a periphery thereof and extending along a longitudinal direction of the outside spindle  41 . The first end of the outside spindle  41  further includes a notch  412  defined in the periphery thereof. An elastic element  45  is mounted in the second end of the outside spindle  41  and around the cylinder bar  341 , with two ends of the elastic element  45  being attached between an end of the cylinder  34  and the cam  42 . The outside hub  33  includes a restraining recessed portion  332  and a groove  333  that are respectively in association with the slot  411  and the notch  412  of the outside spindle  41 , which will be described later. 
     The cam  42  includes an ear  421  projecting radially outward from a periphery thereof and an engaging notch  422  defined in the periphery thereof. Preferably, the ear  421  is diametrically opposed to the engaging notch  422 . As illustrated in FIG. 2, the cam  42  is biased by the elastic element  45  such that the ear  421  of the cam  42  is normally engaged with the retractor  52  when the lock is in an unlocked state. 
     Still referring to FIGS. 1 through 3, the sleeve  43  includes a slot  432  in an end face of an end  431  thereof, and a receptacle  433  is defined in the other end of the sleeve  43 . The lug  44  includes an arm  442  and a ring  441  formed on an end of the arm  442 . The ring  441  is pivotally mounted around the end  431  of the sleeve  43 . The other end  142  of the locking bar  14  is securely engaged in the slot  432  of the end  431  of the sleeve  43 , allowing joint movement (including longitudinal movement and rotational movement) of the locking bar  14  and the sleeve  43 . The cylinder bar  341  of the cylinder  34  is securely engaged in the receptacle  433  of the sleeve  43 , allowing joint rotation of the cylinder bar  341  and the sleeve  43 . The arm  442  of the lug  44  extends through the engaging notch  422  of the cam  42  and the slot  411  of the outside spindle  41 . 
     In assembly, as illustrated in FIG. 2, the engaging notch  422  of the cam  42  is aligned with the slot  411  of the outside spindle  41  to allow the arm  442  of the lug  44  to extend through the engaging notch  422  of the cam  42  and the slot  411  of the outside spindle  41 . Thus, the sleeve  43  and the cam  42  may move jointly along a longitudinal direction of the outside spindle  41 , And the cam  42  and the outside spindle  41  may turn jointly. Further, the arm  442  of the lug  44  extends into the restraining recessed portion  332  of the outside hub  33 . The ear  421  of the cam  42  extends through an opening  351  of the seat  35  and is operably connected to the retractor  52 . 
     Still referring to FIG. 2, when the lock is in an unlocked state and when the outside lever  31  is turned, the outside spindle  41  turns together with the outside lever  31 . Since the arm  442  of the lug  44  extends through the slot  411  of the outside spindle  41  and the engaging notch  422  of the cam  42 , the cam  42  is also turned and thus actuates the retractor  52 , causing retraction of the latch  51  and thus allowing opening of the door to which the lock is mounted. Since the ring  441  of the lug  44  is pivotally mounted around the end  431  of the sleeve  43 , the sleeve  43  is not turned when the outside spindle  41  is turned. The latch  51  returns to its initial position when the outside lever  31  is released. 
     Referring to FIG. 4, when the push button  15  is pushed, the lolling bar  14  is moved inward until two side walls  530  of the catch  53  are respectively engaged in two engaging notches  141  on the locking bar  14  under the action of a spring  531  attached between the outside hub  33  and a connecting wall  532  between the side walls  530  of the catch  53 . Since the other end  142  of the locking bar  14  is securely engaged in the slot  432  of the end  431  of the sleeve  43 , inward movement of the locking bar  14  also causes the sleeve  43  and the lug  44  to move away from the retractor  52 . Thus, the ear  421  of the cam  42  passes trough the opening  351  of the seat  35  and is thus disengaged from the retractor  52 . The ear  421  of the cam  42  is moved to the notch  412  of the outside spindle  41  and the groove  333  of the outside hub  33 . 
     Referring to FIG. 5, when the outside lever  31  is turned while the lock is in the locked state shown in FIG. 4, since the ear  421  of the cam  42  is disengaged from the retractor  52 , the outside lever  31  turns freely without causing retraction of the latch  51 . Thus, damage to the inner parts of the lock resulting from turning of the outside lever  31  while the lock is in the locked state is avoided. The maximum pivotal movement of the outside lever  31  is generally 45 degrees, and it is determined by the arcuate length of the restraining recessed portion  332  of the outside hub  33  that receives the arm  442  of the lug  44 . Namely, when the outside lever  31  is turned, movement of the arm  442  of the lug  44  is limited by two ends of the restraining recessed portion  332  of the outside hub  33 . Further, the groove  333  of the outside hub  33  has an appropriate arcuate length to allow the ear  421  of the lug  44  to turn through a predetermined angle in the outside hub  33  and to allow longitudinal movement of the ear  421 . Further, the depths of the slot  411  of the outside spindle  41  and the raining recessed portion  332  of the outside hub  33  allow longitudinal movement of the arm  442  away from the outside hub  33 . 
     Referring to FIG. 6, when a proper key (not labeled) is inserted into the cylinder  34  and turned through a predetermined angle, the sleeve  43  is turned, as the cylinder bar  341  of the cylinder  34  is securely engaged in the receptacle  433  of the sleeve  43 . The locking bar  14  is also turned, as the other end  142  of the locking bar  14  is securely engaged in the slot  432  of the end  431  of the sleeve  43 . Thus, the engaging notches  141  (FIG. 2) of the locking bar  14  are disengaged from the side walls  530  of the catch  53 . The lock is no longer in the locked state, as the locking bar  14  returns to its initial position shown in FIG. 2 under the action of a return spring  140 . The sleeve  43 , the lug  44 , and the cam  42  return to their initial position shown in FIG. 2 under the action of the elastic element  45 . 
     According to the above description, it is appreciated that the outer transmission assembly  4  in accordance with the present invention provides a clutch mechanism that allows easy assembly and that is easy to manufacture while allowing the outer handle to rotate freely when the lock is in a locked state so that the internal parts of the lock will not be damaged. 
     Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.