Patent Application
20090064736
1. Field of the Invention
The present invention relates to a latch assembly, and in particular to a latch with an adjustable backset.
2. The Prior Arts
“Backset” refers to the distance from the edge of the door to the center of the pre-drilled hole for the lock. Most tubular locks come in a single size: 60 mm or 70 mm backset. The user needs to know the backset dimension to purchase the lock. If the lock purchased by the user has a backset different from the hole drilled on the door, the lock is unusable. Thus, the lock has only a single backset dimension is restricted to be used on the door having the pre-drilled hole with the same backset dimension. Accordingly, a latch assembly with an adjustable backset has been developed. The latch assembly can change the assembly method of transmission members of the lock and the backset distance can be set to one of two predetermined distances. The latch assembly according to the present invention is more applicable than the conventional latch assembly.
China Patent No. 99248490.1 discloses a “Latch bolt mechanism of a tubular lock with adjustable backset by an extension casing”, which can be adjusted to provide two predetermined backset. The latch bolt mechanism includes a latch bolt housing, a plate assembly including a first plate and a second plate, an actuating plate, a follower plate located between the first plate and the second plate, and an extension casing mounted around an inner end of the plate assembly and movable longitudinally to the plate assembly. One end of the actuating plate includes a hook-shaped connecting member for retracting the latch bolt and the other end of the actuating plate includes an upper tooth and a lower tooth. The follower plate includes an upper tooth and a lower tooth, each of which includes a block formed thereon. When the spindle of the lockset is turned, one of the upper tooth and the lower tooth of the follower plate is pressed by a lateral side of the spindle. The follower plate presses the blocks of the actuating plate, and therefore the follower plate retracts the latch bolt. Moreover, the extension casing includes upper and lower slots in top and bottom sides thereof, respectively. The slots receive the blocks of the follower plate, respectively. Because the slots have a length longer than that of the blocks of the follower plate, the extension casing can drive the follower plate to move relative to the actuating plate and the extension casing can move relative to the follower plate, i.e. the extension casing and the follower plate can have different moving distance relative to the actuating plate. Thus, a latch of a tubular lock is adjusted to form two different backset dimensions by moving the extension casing. However, a disadvantage of this configuration is that this positioning mechanism of the latch bolt can not be adjusted accurately, because when the extension casing moves together with the follower plate between two backset dimensions, the relative moving space between the extension casing and the follower plate is realized by the slots of the extension casing that have a length longer than that of the blocks of the follower plate, and there is no position fixing member for the two different backset dimensions.
The objective of the present invention is to provide a latch assembly with an adjustable backset, by which the latch can be accurately set to one of two predetermined backset. The latch assembly can change from one backset dimension to the other back dimension quickly, conveniently and accurately.
A latch assembly according to the present invention includes a latch bolt, a housing, an actuating plate passing through the housing and connected with the latch bolt, a lower connecting plate connected with the housing and positioned under the actuating plate, an upper connecting plate positioned above the actuating plate, a driving plate mounted between the actuating plate and the lower connecting plate, and a positioning casing, in which the upper connecting plate combined with the lower connecting plate is placed.
The positioning casing is formed with a middle hole on the middle portion for a spindle to pass through, a front hole and a back hole on the front portion and back portion for fixing bolts to pass through respectively, and two protrusions symmetrically located on the left and right side of the middle hole.
The middle portion of the upper connecting plate is formed with a long hole for the spindle to pass through; a first pair of symmetrical recesses corresponding to the protrusions of the positioning casing is formed on both sides of the front portion of the long hole, and a second pair of symmetrical recesses corresponding to the protrusions of the positioning casing is formed on both sides of the back portion of the long hole.
The actuating plate is provided with a long slot along the length direction, and two symmetrical protrusions projecting from the left and right side of the middle portion of the bottom surface of the long slot.
The driving plate is formed with a square hole to allow the spindle pass through, and the front side wall of the square hole is in contact with the protrusions of the actuating plate.
The upper connecting plate is provided with a first hole and a second hole at the front and back ends of the long hole respectively for the fixing bolt to pass through, and a third hole in the front portion of the upper connecting plate.
The lower connecting plate is provided with a long hole on the middle portion for the spindle to pass through, a first hole and a second hole on the front and back ends of the long hole for the fixing bolts to pass through, and a third hole in the front portion of the lower connecting plate.
When the protrusions of the positioning casing are engaged with the second pair of recesses of the upper connecting plate, the middle hole of the positioning casing is aligned with the long hole of the upper connecting plate, the long slot of the actuating plate and the long hole of the lower connecting plate; the front hole of the positioning casing is aligned with the first holes of the upper and lower connecting plates; the back hole of the positioning casing is aligned with the second holes of the upper and lower connecting plates.
When the protrusions of the positioning casing are engaged with the first pair of recesses of the upper connecting plate, the middle hole of the positioning casing is aligned with the long hole of the upper connecting plate, the long slot of the actuating plate, the square hole of the driving plate and the long hole of the lower connecting plate; the front hole of the positioning casing is aligned with the third holes of the upper and lower connecting plates; the back hole of the positioning casing is aligned with the long holes of the upper and lower connecting plates.
The latch assembly of the present invention can be set to two different backset dimensions by configuring the positioning casing, the driving plate and the upper and lower connecting plates without other tool. A larger backset dimension can be obtained by connecting the protrusions of the positioning casing with the second pair of recesses of the upper connecting plate, and a smaller backset dimension can be obtained by connecting the protrusions of the positioning casing with the first pair of recesses of the upper connecting plate. When the larger backset dimension is employed, the spindle is engaged with the actuating plate to retract the latch bolt. When the smaller backset dimension is employed, the spindle is engaged with the driving plate to retract the latch bolt. The latch assembly according to the present invention is configured simply and can be adjusted from a backset dimension to the other backset dimension easily and accurately.
The present invention will be apparent to those skilled in the art by reading the following detailed description of a preferred embodiment thereof, with reference to the attached drawings, in which:
A preferred embodiment in accordance with the present invention will now be described with reference to the accompanying drawings.
With reference to
The housing assembly includes a housing 10, a latch bolt 101, a linking member 102, a clip plate 103, a face plate 104, an anti-theft pin 105, an elastic element 106 and a guarding plate 107. The latch bolt 101 is connected with the linking member 102. The linking member 102 is connected with the clip plate 103 and can be driven by the actuating plate 12.
Referring to
One end of the lower connecting plate 14 is connected with the housing 10. A long hole 143 is formed in the middle portion of the lower connecting plate 14 to allow the spindle 163 to pass through (Referring to
Referring to
The upper connecting plate 11 having the configuration corresponding to the lower connecting plate 14 is provided with a long hole 113 formed in the middle portion thereof. The spindle 165 passes through the long hole 113. The upper connecting plate 11 is also provided with a first hole 115 and a second hole 116 located at front and back ends of the long hole 113 respectively for the fixing bolts to pass through. Also, the upper connecting plate 11 is formed with a third hole 114 at the front portion thereof. A first pair of symmetrical recesses 111 and a second pair of symmetrical recesses 112 are formed at the two sides of the long hole 113. The second pair of symmetrical recesses 112 is positioned at the back portion of the upper connecting plate 11 and the first pair of symmetrical recesses 111 is positioned at the back portion of the upper connecting plate 11. Furthermore, the upper connecting plate 11 is formed with two symmetrical notches 117 corresponding to the clamping blocks 141 of the lower connecting plate 14 on the two edges thereof. The upper connecting plate 11 is assembled with the lower connecting plate 14 by engaging the clamping blocks 141 with the notches 117.
The upper and lower connecting plates 11, 14, the actuating plate 12 and the driving plate 13 are connected together and are disposed in the positioning casing 15. The positioning casing 15 is formed with a middle hole 153 for the spindle 163 to pass through, and is also formed with a front hole 154 and a back hole 155 for the fixing bolts to pass through. Also, two protrusions 151 are formed on the left and right sides of the middle hole 153, respectively. The protrusions 151 can be engaged with the first pair of recesses 111 or the second pair of recesses 112. One end of the positioning casing 15 is provided with two assembly blocks 156 symmetrically placed on the edges for fixing the positioning casing 15.
For assembling the latch assembly, the lower connecting plate 14 is installed in the housing 10 first, and then the actuating plate 12 is installed. In the housing 10, the actuating plate 12 is connected with the linking member 102 and the clip plate 103 to drive the latch bolt 101 to move. Afterward, the driving plate 13 is installed between the actuating plate 12 and the lower connecting plate 14. The first assembly plane 131 of the driving plate 13 is engaged with the first protrusions 121 of the actuating plate 12, whereby the driving plate 13 can drive the actuating plate 12 to unlock the lock. Then the upper connecting plate 11 is installed by engaging the clamping blocks 141 of the lower connecting plate 14 with the notches 117 of the upper connecting plate 11. Meanwhile, the second protrusions 122 of the actuating plate 12 are in contact with the upper connecting plate 11 tightly for preventing the actuating plate 12 from shaking. Finally, the outside of the upper connecting plate 11 and the lower connecting plate 14 is covered with the positioning casing 15, and then the assembly blocks 156 are riveted. Thus the assembly process of the latch is completed.
From above all, the latch according to the present invention can be set to two backset dimensions without any tools. The latch assembly can be accurately kept at the predetermined backset dimension and can prevent the backset dimension from being unintentionally changed to other dimensions. Therefore, the latch assembly according to the present invention has a simple structure and can adjust the backset dimension conveniently.
Although the present invention has been described with reference to the preferred embodiment thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.
