Patent Publication Number: US-6213523-B1

Title: Lock

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns a lock having a bolting means for bolting a latch bolt. 
     2. Description of the Background Art 
     More precisely, this invention concerns a lock installable in, e.g., a door leaf. The lock includes a case and a latch bolt movable within the case between a locking position, in which the latch bolt at least partly projects from the case, and an unlocking position, in which the latch bolt is retracted within the case. Generally, a lock of this kind includes some kind of bolting means adapted to bolt the latch bolt in at least its locked position. Such bolting means is generally factory mounted on one side of the case for access from a corresponding side of a door. Consequently, to comply with possible customer needs, it is necessary to manufacture two locks having the bolting means on opposite sides of the case. 
     U.S. Pat. No. 5,779,287 discloses a lock having an optional bolting means, i.e., a bolting means that is separately delivered with the lock and that may be mounted in the lock by the user at need. This prior art lock includes a lock case having opposed walls and a latch bolt slidable between a locking position and an unlocking position. Each of the opposed walls is provided with an aperture for optionally receiving a holding bolt. The holding bolt is positionable in each aperture in a first, relatively retracted position allowing sliding of the latch bolt from its locking position to its unlocking position, and in a second relatively inserted position preventing sliding of the holding bolt from its locking position to its unlocking position. The optional bolting means further includes a spring for yieldably retaining the holding bolt in its first and second positions. The apertures are shaped such that once the holding bolt has been introduced in a selected aperture, it is automatically kept there by the spring pressing it towards a portion of the aperture preventing its withdrawal. However, withdrawal of the holding bolt is possible upon manually rotating it through a small, limited angle against the action of the spring. Since the free end of the holding bolt of this prior art lock needs to be axially and radially guided, the lock requires a relatively thick door leaf and particularly an escutcheon mounted onto the door leaf to guide the holding bolt and also to prevent its rotation and unintentional removal. 
     OBJECT OF THE INVENTION 
     A first object of the present invention is to provide a lock of the general kind stated preventing unintentional removal and allowing intentional removal of the holding bolt without rotational movement thereof. A second object is to provide such a lock needing neither a relatively thick door leaf nor an escutcheon to guide its holding bolt. 
     SUMMARY OF THE INVENTION 
     The first object stated above has been achieved in a lock including a lock case, a forend attachable to said case by means of removable fastening means, a latch bolt movable within said case between a locking position, in which it at least partly projects from the case, and an unlocking position, in which it is retracted within the case, a holding bolt having a defined cross section and being positionable in a first, relatively retracted position allowing movement of said latch bolt from its locking position to its unlocking position, and in a second relatively inserted position preventing movement of said holding bolt from its locking position to its unlocking position, and spring means for yieldably retaining said holding bolt in its first and second positions and for positively preventing withdrawal thereof from said case, wherein at least one portion of said spring means is movable between a first position, in which it prevents withdrawal of said holding bolt, and a second position, in which it allows withdrawal of said holding bolt, movement of said at least one portion from said first to said second position being enabled by at least partial removal of said fastening means. 
     The second object has been achieved in that said case accommodates a guide means having a guide aperture for guiding movement of said holding bolt, said guide aperture having a cross section adapted to said defined cross section, said at least one portion of said spring means extending across at least a portion of said aperture in said first portion of said spring means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will be apparent from the following non-limiting description of a preferred embodiment, reference being made to the annexed drawings, wherein: 
     FIG. 1 is a perspective side view of the lock having a holding bolt mounted therein; 
     FIG. 2 is a corresponding perspective view showing the lock of FIG. 1 having one half of the lock case removed; 
     FIG. 3 is a partly sectioned side view at an enlarged scale showing the lock having the holding bolt removed and further showing the holding bolt retaining means in an active position; 
     FIG. 4 is a view corresponding to FIG. 3 but showing the holding bolt retaining means in an inactive position; 
     FIG. 5 is a perspective view at an enlarged scale of a guide and ratchet member for the holding bolt; and 
     FIG. 6 is a perspective view at an enlarged scale of the holding bolt shown in FIGS.  1  and  2 . 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     The lock according to the present invention has a lock case  1  consisting of two equal halves  1   a ,  1   b . The case includes two opposed side walls  2  and  3 , an upper wall  4 , a lower wall  5 , a front wall  6  and a back wall  7 . A forend  8  has two holes  9  and  10  for attachment of the lock to, e.g., a door leaf. Two screws  11  and  12  attach the forend to the front wall  6 . The forend also has a rectangular opening  13  through which a latch bolt  14  is slidable between a foremost, locking position, in which it projects from the case, as seen in FIGS. 1,  2  and  3 , and a non-shown, unlocking position, in which it is backwardly retracted within the case so as to leave its front edge  14 ′ substantially flush with the forend  8 . The latch bolt has a recessed portion  15  forwardly defined by a shoulder  16  (FIG.  3 ). In the backward direction a corresponding shoulder is divided in two shoulders  17   a,    17   b  separated by a slot  18  extending from the backward end of the latch bolt about half way to its forward end. 
     The latch bolt is operable by means of a follower  19  having a square hole  20  intended for insertion therein of a square rod connected to a handle for rotating the follower through a limited angle. A helical spring  21  having its coil  22  positioned about a lug  23  bent in from the side wall  3  has a first straight end portion  24  bearing on the inner side of the lower wall  5  and a second straight end portion  25  bearing on the shoulder  16  of the latch bolt, so as to urge the latter towards its locking position shown in FIGS. 1,  2  and  3 . As appears particularly from FIG. 3, the follower  19  is of the kind having two aligned wings  26   a,    26   b  abutting a respective one of the shoulders  17   a,    17   b.  This known arrangement ensures that a handle associated to the follower  19  may operate the latch bolt in both rotational directions of the follower against counteracting forces of the spring  21 . 
     In order to bolt the latch bolt so as to prevent movement thereof towards its open position there is provided a bolting means comprising a holding bolt  27  (FIG.  6 ). The holding bolt is insertable through an L-shaped aperture  28  in wall  2  (FIG. 1) so as to at least partly extend through a corresponding aperture  28 ′ in wall  3  (FIG.  3 ). In its inserted state, the holding bolt is moveable between a relatively retracted, unbolting position and a relatively inserted, bolting position. The holding bolt  27  includes a straight, flat main portion having in one end a handle portion  29  and in its opposite, inner, or foremost end a guide portion  30  having an L-shaped cross section with a longer leg  31  (corresponding to the main portion) and a shorter leg  32 . The portion  30  includes a bolting member  33  extending past the main part of the shorter leg  32 . In the bolting position of the holding bolt, this bolting member is positioned in the path of movement of a rear surface  17 ′ of the latch bolt  14  so as to prevent movement thereof towards its unlocking position. The bolting member  33  also provides an abutment shoulder  34 . At the inner or forward end of the bolt there are provided in an edge  35  of the main portion a ratchet retaining means including a first and a second recess  36  and  37  separated by a smoothly curved ridge  38 , and a positive retaining means comprising a shoulder  39  being substantially perpendicular to the edge  35 . 
     In order to guide movement of the holding bolt and to yieldably retain it in its unlocking and locking positions, there is provided a guide and ratchet member shown separately in FIG.  5 . This member is an integral structure, preferably made of a synthetic resin, including a stationary portion  40  and a movable leg portion  41  joined to the stationary portion by a resilient portion  42 . Portion  40  is kept stationary relative to the lock case by means of opposed circular bosses  43  fitting in corresponding bores  44 ,  44 ′ in the lock case walls  2  and  3 , respectively, and likewise opposed protrusions  45  fitting in the L-shaped apertures  28 ,  28 ′, respectively. A guide opening  46  extends through the protrusions  45  and the stationary portion  40  so as to smoothly guide lengthwise movement of the holding bolt. The guide opening has an L-shape conforming to the cross section of the foremost end of the holding bolt, i.e., its longer leg  31  and shorter leg  32 , such that the abutment shoulder  34  restricts movement of the holding bolt in a forward direction by abutting an abutment surface  47  of the stationary portion  40 , thus defining the bolting position of the holding bolt. 
     In order to yieldably retain the holding bolt in its unlocking position and its locking position, there is provided a retaining means in the shape of a helical spring  48  (FIG. 3) having its coil  49  positioned about a cylindrical post  50  provided on the moveable portion  41 . The spring  48  has a first substantially straight end portion  51  bearing on a wall  52  of a substantially horizontal slot  53  in the leg portion  41 . A second substantially straight end portion  54  of the spring extends through a substantially vertical slot  55  (FIGS. 3 and 5) through the leg portion  41  and bears on an inner wall  56  thereof. 
     As appears from FIG. 3, the screw  11  abuts the free end  41 ′ of the leg portion  41 , thus restricting possible movement thereof to the left of FIG.  3 . In this position, the resilient portion  42  of the guide and ratchet member, in its relaxed state having a moderately curved shape as shown in FIG. 5, adopts a more sharp bend substantially conforming to the inner corner between case walls  4  and  7 . In this position, the leg portion  54  extends through the cross section of the guide opening  46 . Now, when inserting the holding bolt  27  in the guide opening  46 , a bevelled corner  30 ′ (FIG. 6) of its guide portion  30  encounters the straight end portion  54  of spring  48  and, upon further insertion, presses it to the left until it comes to rest against the edge  35  and slide therealong until it snaps into the foremost recess  36 . In this position, which is the unlocking position, withdrawal of the holding bolt is prevented by the shoulder  38  abutting the spring end portion  54 . This, in turn, is supported by the walls of the slot  55  so as not to flex in the direction of withdrawal. However, further insertion of the holding bolt is possible due to the smoothly curved ridge  38  forcing the spring end portion  54  to yield outwardly and then snap into the second recess  37 . In this position, which is the locking position of the holding bolt, the abutment shoulder  34  contacts the abutment surface  47  provided on the stationary portion  40  of the guide and ratchet member and prevents further insertion into the lock case. 
     The lock according to the present invention is primarily intended to be delivered to customers without the holding bolt mounted. As appears from the drawings, there are provided in each half  1   a,    1   b  of the lock case two L-shaped apertures  28 ,  28 ′ and two bores  44 ,  44 ′. This enables the lock to be factory mounted with two guide and ratchet members. If, on the other hand, the lock is delivered with merely one guide and ratchet member as shown, the customer may shift the position of the guide and ratchet member at will. 
     Once the lock has been inserted into a corresponding recess in a door leaf and fastened to an edge thereof by means of screws through the holes  9 ,  10 , and then the holding bolt has been inserted into the lock as described above, the holding bolt can no longer be retracted beyond the unlocking position, and, consequently, the lock cannot be removed from the door. 
     In order to enable retraction of the holding bolt, and, thus, to enable removal of the lock, the present invention provides for withdrawal of the spring end portion  54  such that it no longer passes the cross section of the aperture  46 . This has been achieved by the provision of the movable leg portion  41  of the guide and ratchet member carrying the spring  48  and by its support against the end of screw  11 . By simply unthreading the screw  11  as shown in FIG. 4, the movable leg portion carrying the coil  49  of spring  48  will be caused by the spring force of the resilient portion  42  adjoining the movable portion and the stationary portion of the guide and ratchet member to move to the left in FIG.  3 . At the end of such movement, the end  41 ′ of the movable portion may come to rest against the inner side of case wall  6  as shown in FIG.  4 . In any case, and as likewise shown, the spring end portion  54  has left the cross section of the aperture  28  which, thus, is open for withdrawal of the holding bolt. After wihdrawal of the holding bolt and removal of the lock from its location in a door leaf, the screw  11  may be screwed in again to make the lock ready for renewed mounting, possibly with the holding bolt inserted through an alternate aperture  28 .