GB1560950A - Latch mechanism with jamb mounted latch bolt - Google Patents

Description

(54) LATCH MECHANISM WITH JAMB MOUNTED LATCH BOLT (71) I, YOUNG Ho YAN, a Chinese citizen of 820 Alpine Street, # 3, Los Angeles, California 90012, United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to improved latch mechanisms for releasably holding a door or the like in closed condition.The invention is in certain respects especially effective for use in conjunction with swinging doors, and to simplify this disclosure will be described and shown as applied to that use but without limiting the scope of the claims to preclude coverage of the mechanism when employed for latching other types of moveable members for which the mechanism may be adapted.

The conventional type f door lock employed in the constructlon industry includes a spring urged latch bolt which is moveably carried by the door, and is adapted to engage and be deflected by, and co-act in holding relation with, a keeper carried by an adjacent jamb. Knobs carried by the door release the latch bolt to permit opening of the door, and may be controlled by a key operated lock unit preventing such release of the bolt.

One difficulty which has been encountered with such prior conventional door locks has been the relative ease with which an unauthorized person can, from the outside of the door, move the latch bolt to the retracted position without use of a key. More specifically it is relatively easy with most of these prior locks to insert a thin element such as a knife blade, credit card or any of numerous other similar items which may be readily available, into the narrow space between the edge of the door and the adjacent jamb in a manner contacting the inclined cam or wedge face at the outer side of the latch bolt and exerting force there against to deflect the bolt to its retracted position permitting opening of the door.Because the cam face of the latch bolt is at the side of the bolt facing toward the outside of the door any appropriate instrument inserted between the door and jamb can easily contact that surface and deflect it to a retracted position with little or no skill required.

Various expedients have been devised in the past for attempting to prevent such unwanted retraction of a latch bolt of the above discussed type. For example, in some locks currently on the market a second spring pressed element is provided adjacent the latch bolt proper, and is deflected by the keeper, when the door is closed, to a position in which it is intended to block such retraction of the bolt by other than the key actuated unit. However, the prior devices of this type of which I am aware are not as affective as would be desired, and can usually be defeated with only very little more manipulation than when the second spring pressed element is not present.An unauthorized person can still exert retracting force against the cam face of the latch bolt by a thin card or element as discussed, and in most cases release it for retraction by jiggling the door while such force is applied.

The present invention overcomes these inadequancies of the conventional type of door lock by providing a latch mechanism comprising: a latch bolt assembly to be mounted to a jamb; and a keeper assembly to be mounted to a member which swings relative to the jamb between open and closed positions, with said keeper assembly being received opposite said latch bolt assembly in closed position of said member; said latch bolt assembly including a latch bolt mounted for sliding movement along a predetermined axis toward and away from said keeper assembly and retracted positions and yieldingly urged to said active position, said latch bolt having a peak portion with a latching surface at one side thereof and a camming surface at its opposite side inclined with respect to said axis:: said keeper assembly including a keeper structure having a portion adapted to engage said camming surface and deflect said latch bolt from said active position toward said retracted position upon closing movement of said member, and to then release said latch bolt for return to said active position to retain said member in closed position; said keeper assembly including a housing, a retracting part which is mounted in said housing for sliding movement in a direction to move esssentially along said axis when said member is in its closed position, and manually operated means for sliding said retracting part axially toward said bolt to retract it;; said retracting part having an end portion which is narrower than said latch bolt in a direction transverse to said axis, and which is located axially opposite said peak portion of the latch bolt in said closed position of said member, and is upon axial sliding movement of said part engageable with said peak portion of the latch bolt to push the bolt axially from said active position thereof toward said retracted position and thereby free said member for opening movement;; said housing having a wall which is laterally adjacent said end portion of said retracting part, and which in said closed position of said member is axially opposite said camming surface of the bolt, and which defines a side of a passage narrower than said bolt, in a direction transverse to said axis through which said end portion of the retracting part projects axially past said wall to engage and act against said peak portion of said bolt; said keeper assembly including a spring urging said retracting part away from said latch bolt.

The invention will be better understood from the following detailed description given by way of example only with reference to the figures of the accompanying drawings, in which: Figure 1 is a fragmentray perspective representation of a swinging door having a lock constructed in accordance with the invention; Figure 2 is an enlarged fragmentary horizontal sectional view taken in the plane 2-2 of Figure 1, but showing the lock mechanism as it appears when the door is closed; Figure 3 is a view similar to Figure 2 but showing the latch bolt as it appears when retracted to permit opening of the door; Figure 4 is a view similar to Figures 2 and 3, but showing the door during closing movement; Figure 5 is a view in oblique perspective of the external appearance of the latch assembly carried by the door jamb;; Figure 6 is an exploded view in oblique perspective of the latch assembly of Figure 5; Figures 7, 8, and 9 are detailed views in oblique perspective showing the latch bolt as it appears from different angles; Figures 10 and 11 are framgentary sectional views taken on section stations 10-10 and 11 11 of Figure 2; Figure 12 is a view in oblique perspective showing the external appearance of the door carried keeper structure Figure 13 is a view in oblique perspective of a portion of the door carried mechanism; Figure 14 is an exploded view in oblique perspective of the door carried mechanism; Figure 15 is a view in oblique perspective of the latch bolt retracting part; and Figures 16, 17, and 18 are rear sectional view taken on section stations 16-16, 17-17 and 18-18 respectively of Figure 2.

In Figure 1 a door shown generally at 10 is mounted within a typically vertical doorway 11 by hinges 12 (one only is shown) for swinging movement about frame 12A and vertical axis 13 in the opening and closing directions. A lock mechanism 14 is adapted to retain the door 10 in the closed position and includes a latch bolt assembly 15 carried by vertical jamb 16 defining the other side of the doorway from frame 12A, and a door carried keeper assembly 17 actuable by two inner and outer knobs 18 and 19. As seen in Figures 2, 3 and 4, latch assembly 15 carried by the vertical jamb the includes a spring pressed latch bolt 20 moveable between the positions of Figures 2 and 3, while the door carried assembly 17 includes a slide part 21 that is adapted to retract the latch bolt 20 to the Figure 3 position.

In Figure 6 elements of the jamb carried latchbolt assembly 15, including the latch bolt 20, a housing 22 moveably containing the latch bolt, a helical compression spring 23 urging the latch bolt 20 to its outwardly projecting position of Figure 2, and a plate 24 disposed across the front side of the housing. The housing 22 is a rectangular prism, having horizontal top and bottom walls 25 and 26 (Fig. 10), vertical side walls 27 and 28, and an inner vertical wall 29, one or more of which walls contain vent openings 30 (Fig. 6) for venting air into and out of the housing behind latch bolt 20 to avoid resistance by compressed air to the movement of the said latch bolt. The housing is received within a recess 31 in jamb 16, with plate 24 at the forward side of the housing having its outer planar surface 32 disposed in the plane of jamb 16, surface 33 which faces and is parallel to edge surface 34 of the door. Plate 24 may be rectangular and dimensioned in correspondence with an outer rectangular flange 35 carried by housing 22, and is suitably secured to flange 35 in fixed relation thereto, as by providing plate 24 with rearwardly extending tubular rivet portions 36 which extend through openings 37 in flange 35 and are deformed to enlarged diameter conditions beyond those openings to hold the two plates 24 and 35 together. The passages through rivets 36 then define openings through which screws 38 may extend to secure assembly 15 to the jamb 16.Extending along its outer edge (that is, the edge nearest the outside of doorway 11), plate 24 has a vertical projection or rib 39, which projects a substantial distance beyond the plane of jamb surface 33 and plate surface 32 and toward the edge 34 of the door, to essentially close the gap at that location between the door 10 and jamb 16 in a relation blocking unwanted insertion through that gap of a hook shaped or other tool whch might be used to engage and retract latch bolt 20.

The latch bolt 20 is shaped to fit relatively closely within housing 22, in a relation guiding the latch bolt 20 for movement only along a predetermined horizontal axis 40 (Fig. 2) which is perpendicular to the edge 34 of the door 10.

As will be apparent from Figure 10, the latch bolt 20 is of essentially rectangular section transversely of axis 40, having planar horizontal top and bottom surfaces 41 and 42 and planar vertical side surfaces 43 and 44, with a rectangular recess 45 being formed in the back side of the latch bolt partially to receive helical spring 23 so that the said spring exerts an axial force in opposite directions against the housing and latch bolt yieldingly to urge the latch bolt to its outwardly projecting position of Figure 2. At one of its sides, the latch bolt 20 may have two projections 46 and 47 which project into close proximity to a side wall 28 of housing 22.The forward one of these projections 46 is engageable against the back side of plate 24 in the Figure 2 position of the latch bolt 20 to limit the spring urged movement of the latch bolt and determine the extent of projection of the latch bolt from the plate through a rectangular opening 471 in the plate. The portion of the latch bolt that projects outwardly beyond the plate in the Figure 2 position is a peak portion having at one side a planar vertical latching surface 48 disposed parallel to axis 40, and at its opposite side by an inclined camming surface 49 disposed at a camming angle a with respect to axis 40. A vertical nose surface 50 may be formed at the outer end of the latch bolt, with the top and bottom of the projecting portion of the latch bolt being defined by the above mentioned planar horizontal surfaces 41 and 42.

The door carried keeper assembly 17 includes a housing 51 (Fig. 13), which moveably contains the latch bolt retracting slide part 21, and which is mounted within an appropriately shaped recess 52 cut into the door 10 from its edge 34. A communicating recess 53 extending through the door enables mounting of knobs 18 and 19 (Fig. 1, 2) in essentially conventional manner and in a relation to operate latch bolt retracting part 21.

The housing 51 is formed of two complementary parts 54 and 55 (Fig. 14), which meet at a plane 56, and are secured rigidly together by a rivet 57 extending through aligned openings in the two complementary parts. The first housing part 54 carries a planar flange 58 at its outer end, to which a keeper or strike plate 59 is rigidly secured, as by providing plate 59 with rivet portions 60 extending through openings 61 in flange 58 and flared at their inner ends to secure the plates 58 and 59 tightly together. Plate 59 is planar except at the location of an outer angularly disposed camming tab or strike plate 62, with the outer planar surface 162 of plate 59 being disposed perpendicular to axis 40 in the Figure 2 position of the mechanism, and lying in the plane of the surface of the edge 34 of the door.

Plates 58 and 59 contain openings 63 and 64 through which latch bolt 20 projects in the latched condition of the mechanism. In that condition, the flat surface 44 of the latch bolt 20 engages vertical edge 65 of opening 64 in plate 59 positively to block opening movement of the door 10.

The retracting slide part 21 is confined closely, within a guideway 66 in housing 51, in a relation guiding slide part 21 for only sliding movement along axis 40 of Figure 2.

Upon such movement, a rectangular end portion 67 of slide part 21 is moveable from the Figure 2 position to the Figure 3 position, to retract latch bolt 20 to its door releasing position of Figure 3. End portion 67 of the slide part 21 occupies only a portion of the transverse extent of the guideway 66 in housing 51, with the remainder of that cross section at one location being occupied by a transverse wall portion 68 (Figs. 2 and 14) of part 55 of the housing 51. This wall portion 68 is located sufficiently far to the right of the plane of plate 59 in Figure 2 to define a socket recess within which the end of latch bolt 20 is receivable in the latched condition of Figure 2.At its inner or rear side, wall portion 68 engages a helical coil spring 69, one end of which bears against a transverse shoulder 70 (Fig. 14) formed on retracting slide part 21 yielding to retract that slide part to its Figure 2 position. An elongated slot 71 formed in retracting slide part 21 allows extension of rivet 57 through it without interfering with axial movement thereof. A wall 72 formed on retracting slide part 21 confines the engaged end of spring 69 against movement toward slot 71, and a recess 169 in wall portion 68 receives and locates the other end of helical spring 69. The axial movement of slide part 21 is limited by provision of a pair of lugs 73 formed at the top and bottom of slide part 21, and slidably received within slots 74 formed in the top and bottom walls of housing part 54.More specifically, movement of slide part 21 in a rightward direction as viewed in Figure 2 is limited by engagement of preferably inclined wedging surfaces 75 formed on lugs 73 with correspondingly inclined wedging surfaces 76 formed at the inner ends of slots 74, while movement of slide part 21 in a leftward direction is limited at the Figure 3 position by engagement of surface 175 on the lugs 73 with end surface 176 of the slots (see Fig. 14). At its inner end, slide part 21 may have a plate or flange portion 77 disposed transversely of axis 40 and having a planar transverse end surface against which force is exerted to move slide part 21 to the left as seen in Figure 3.

Each of the knobs 18 and 19 is mounted in conventional manner by a mounting flange structure represented generally at 79, to be manually turned about an axis 80 which is perpendicular to the previously discussed axis 40. At its inner end, knob 19 has an arcuate portion 81 (Figs. 2 and 16), which is adapted to be turned by the knob about axis 80 and when so turned to act against flange 77 in a relation actuating retracting slide part 21 from the Figure 2 positioned to the Figure 3 position. Similarly, knob 18 has an arcuate portion 82 which that knob turns about axis 80 to actuate slide part 21 to its Figure 3 position. A manually actuated control element 83 is operable to lock a conventional holding mechanism represented diagrammatically at 84 in Figure 2, in a relation locking knob 19 against turning movement.

This control element is typically illustrated as a known type of push button 83 located adjacent knob 18 and adapted to lock knob 19 when push button 83 is pressed axially inwardly. However, push button 83 may alternatively be any other known type of control element, such as for example a rotary element mounted in the center of knob 18. Mechanism 84 may be released by actuation of a conventional key controlled lock unit 86, typically mounted within the centre of knob 19 and accessible for key actuation at the centre of that knob. Since all of this knob and key controlled mechanism may take any of different very well known and conventional forms, no attempt has been made in the drawings to illustrate any particular mechanism in detail.It may be noted, however, that in order to assure and maintain proper relationship between the knobs and the mechanism controlled thereby, there may be attached to one of the knob mounting units 79 a stationary structure represented at 87 in Figures 2 and 16, projecting into recess 53 of the door and having an arcuate portion 88 which backs up and locates slide actuating portions 81 and 82.

The structure 87 may also have two spaced portions 89 which are received witin upper and lower grooves 90 in housing 51 to locate that housing relative to the knob mechainism.

During assembly of the parts, element 87 may be moved in a direction parallel to axis 80 to slidably interfit with grooves 90 of housing 51.

The modus operandi of the latch mechanism is as follows:-- assume that the door 10 is initially in the closed condition of Figure 2 in which latch bolt 20 retains the door 10 against opening movement (downward movement of the door as view in Fig. 2). Assume also that mechanism 84 has been set by actuation of push button 83 to a locked condition, in which it prevents turning movement of outer knob 19. If an unauthorized person then attempts to enter the door 10 from its outer side (the side located at the top of Fig. 2), he cannot turn knob 19 and therefore is precluded from entering. Further, if he attempts to insert a knife blade, for example into the space between surfaces 33 and 34 at the jamb 16 and door, from the side of the door at which knob 19 is located, he cannot push the blade against camming surface 49 of the latch bolt 20 .This is so because cam surface 49 is located at the inner side of the latch bolt 20, that is, the side facing away from the position from which the unauthorized person is attempting to release the latch bolt 20. The only way he might attempt to force the latch bolt 20 to its retracted Figure 3 position is by utilizing some type of special instrument having a hook shape to reach about and behind the latch bolt 20 and engage its rear cam face.

This type of actuation, however, is difficult, requires a special instrument, and in addition is precluded or rendered more difficult by provision of the blocking rib or projection 39 at the outer edge of plate 24. The entire assembly is thus much more difficult to defeat than is a conventional door lock.

Authorized persons block the door 10 by insertion of a key within unit 86 at the outside of the door, with the key serving when turned relative to the knob to turn arcuate projection 81 associated with the knob (see broken line position of Fig. 16), in a relation pushing slide part 21 leftwardly from its Fig. 2 position to its Figure 3 position, thus to actuate latch bolt 20 to a retracted position slightly beyond the plane of the outer surface of camming tab or strike plate 62, so that the door 10 may be pushed open and the latch bolt 20 will slide from the outer surface 91 (Fig. 15) of slide part 21 onto the outer surface of plate 59 and across that surface to its edge 92. When the door is subsequently closed the angularly disposed camming tab 62 of plate 59 engages inclined camming surface 49 of latch bolt 20 as seen in Figure 4 to deflect that latch bolt 20 progressively leftwardly far enough to enable the keeper or strike plate 59 to move past the latch bolt 20 until the spring pressed bolt can fall into opening 64 in plate 59 to the latched position of Figure 2. When the key controlled mechanisms 84 and 86 are not locked, either of the knobs 18 or 19 may be turned freely, and when so turned in either direction will actuate slide part 21 to retract latch bolt 20 and permit opening of the door 10.

Claims (15)

1. WHAT I CLAIM IS

   I. A latch mechanism comprising: a latch bolt assembly to be mounted to a jamb; and a keeper assembly to be mounted to a member which swings relative to the jamb between open and closed positions, with said keeper assembly being received opposite said latchbolt assembly in closed position of said member; said latch bolt assembly including a latch bolt mounted for sliding movement along a predetermined axis toward and away from said keeper assembly and between active and retracted positions and yieldingly urged to said active position, said latch bolt having a peak portion with a latching surface at one side thereof and a camming surface at its opposite side inclined with respect to said axis;; said keeper assembly including a keeper structure having a portion adapted to engage said camming surface and deflect said latch bolt from said active position toward said retracted position upon closing movement of said member, and to then release said latch bolt for return to said active position to retain said member in closed position; said keeper assembly incuding a housing, a retracting part which is mounted in said housing for sliding movement in a direction to move essentially along said axis when said member is in its closed position, and manually operated means for sliding said retracting part axially toward said bolt to retract it;; said retracting part having an end portion which is narrower than said latch bolt in a direction transverse to said axis, and which is located axially opposite said peak portion of the latch bolt in said closed position of said member, and is upon axial sliding movement of said part engageable with said peak portion of the latch bolt, to push the bolt axially from said active position thereof toward said retracted position and thereby free said member for opening movement;; said housing having a wall which is laterally adjacent said end portion of said retracting part, and which in said closed position of said member is axially opposite said camming surface of the bolt, and which defines a side of a passage narrower than said bolt, in a direction transverse to said axis, through which said end portion of the retracting part projects axially past said wall to engage and act against said peak portion of said bolt; said keeper assembly including a spring urging said retracting part away from said latch bolt.
2. 2. The latch mechanism as claimed in claim 1, in which said spring, in said closed position of said member, is positioned axially opposite said camming surface of said bolt, with said wall located between said camming surface and said spring.
3. 3. The latch mechanism as claimed in claim 1, in which said spring is offset entirely to a predetermined side of said end portion of said retracting part and located axially opposite said camming surface of the bolt and beyond said wall in a direction away from the bolt, and acts in opposite directions against said wall and said retracting part respectively.
4. 4. The latch mechanism as claimed in claim 1, in which said retracting part has a widened portion which is wider than said end portion and is located axially beyond said wall in a direction away from said latch part, said spring being a coil spring located entirely at one side of said end portion of the retracting part and located axially opposite said camming surface of the latch bolt in the closed position of said member, and acting in opposite directions against said wall and said enlarged portion of the retracting part to urge the latter to an inactive position thereof.
5. 5. The latch mechanism as claimed in claim 4, in which said housing includes two complementary sections meeting in a predetermined plane and one of which slidably contains said end portion of the retracting element, the other of said sections carrying said wall and a part of said widened portion of said retracting part and said spring.
6. 6. A latch mechanism as claimed in claim 5, including a pin connected at opposite ends to said two housing sections and extending through an elongated slot in said retracting part, and lugs projecting from said retracting part into recesses formed in said one section of the housing adjacent said plane.
7. 7. The latch mechanism as claimed in any of claims 1 to 5, including a pin connected to said housing and extending through an elongated slot in said retracting part.
8. 8. The latch mechanism as claimed in any of claims 1 to 4, in which said housing includes two complementary sections slidably receiving and containing said retracting part and one of which carries said wall.
9. 9. The latch mechanism as claimed in any of claims I to 4, in which said housing includes two complementary sections slidably containing said retracting part and one of which contains a recess closed at one side by the other section and into which a lug on said retracting part projects to limit axial movement thereof.
10. 10. The latch mechanism as claimed in any of claims 1 to 4, in which said housing includes two complementary sections slidably containing said retracting part and one of which contains a recess closed at one side by the other section and into which a lug on said retracting part projects to limit axial movement thereof, there being a pin connected at opposite ends to said two sections and ex tending through an elongated slot in said retracting part.
11. 11. The latch mechanism as claimed in any of the preceding claims, in which said manually actuated means include a handle accessible from an outer side of said member for actuating said retracting part to retract said latch bolt, and a key operated lock for releasably locking said handle against latch bolt retracting movement.
12. 12. The latch mechanism as claimed in any one of the preceding claims in which said latch bolt assembly including means forming a projection located at the side of said latch bolt at which said latching surface is formed, and projecting to a location blocking movement of an instrument toward the latch bolt to thereby prevent unauthorized retraction.
13. 13. The latch mechanism as claimed in claim 12, in which said latch bolt assembly includes a plate containing an opening through which said latch bolt projects in said active position thereof, said plate carrying said projection at said side of the latch bolt at which said latching surface is formed.
14. 14. The latch mechanism as claimed in claim 13, in which said projection is elongated to extend along the entire height of the latch bolt.
15. 15. A latch mechanism substantially as hereinabove described with reference to and as shown in the Figure of the accompanying drawings.