Automatic bolt lock

A bolt fits slidably within a cylinder and is inserted in a drilled hole through a first slidable member to be interlocked. The bolt, under force of a coil spring within the cylinder, is forced into any of a series of aligned holes in a second member to be interlocked. A striker plate with aligned holes is attached to the second member and receives the end of the bolt as it slides until forced into a hole. A body is attached to the cylinder and the body is secured to the slidable first member to be interlocked. A D-spring on the body engages a D-spring notch on the bolt, locking the bolt in the projected position, thereby interlocking the two members. The body and handle, attached to the bolt, have flat surfaces which when aligned indicate that the D-spring is engaged to the D-spring notch. The handle must be rotated to disengage the D-spring and D-spring notch before the handle and bolt can be retracted. A secondary pair of D-spring notches forward on each side of the bolt at 90 degrees to the first D-spring notch engage the D-spring to retain the bolt in a retracted unlocked position for free sliding of the two members. Sliding windows, sliding doors, movable shelves and other slidably interactive members may be locked together.

DESCRIPTION 
BACKGROUND OF THE INVENTION 
TECHNICAL FIELD 
The present invention relates to devices for locking windows, sliding doors 
and shelves in place and in particular a device whose bolt cannot be 
shaken or jiggled out of its locked position and which automatically locks 
into position when it reaches a hole. 
BACKGROUND ART 
Devices to lock windows and sliding doors in position are often difficult 
to install because of numerous parts which must be installed in the 
different parts of the windows or sliding doors. 
In most tamper-proof locks, keys, magnets and the like are often required 
to retract the locking device, which can be dangerous if an emergency 
requires opening the window or sliding door immediately, and the key, 
magnet or the like is not readily available. 
Other devices which do not require a key, magnet or the like are not child 
proof because a child can easily retract the locking device. 
The handles of other devices give no indication of the position of the 
lock. 
The handles of other locking devices may allow gripping of burgular tools 
when the window or door is locked or partially open for ventilation. 
DISCLOSURE OF INVENTION 
The present invention provides an easily installed device for locking 
windows and sliding doors in position because it requires only one 
drilling operation and it may be inserted into position in one piece and 
simply screwed in place. 
The bolt may be retracted without the use of a key, magnet or the like by 
rotating the handle and retracting the handle until the bolt is locked in 
the retracted position thereby allowing quick and easy unlocking of the 
window or sliding door in an emergency. 
The design of the device makes it essentially child proof because the 
operation requires a special turning and pulling action for proper 
orientation to engage and disengage the bolt, not apparent to someone 
unfamiliar with the lock's operation. 
The tapered shape of the handle prevents gripping by burgular tools and the 
flush fit between the handle and body prevents insertion of burgular tools 
when the window or door is locked partially open for ventilation. The 
requirement that the handle must first be rotated before the bolt can be 
retracted makes defeating the device by the use of burgular tools very 
difficult. The hardened steel bolt itself is not easily cut through or 
broken.

BEST MODE FOR CARRYING OUT THE INVENTION 
In FIG. 1 the preferred embodiment of the lock body 50 comprises a flat 
truncated circular plate with a C-shaped protrusion 48 extending from the 
front side forming a short cylinder truncated along the top. A primary 
central hole 54 extends through the body 50 and the C-shaped protrusion 
48. Secondary holes 52 on either side of the first hole 54 receive 
fastening means, such as self-tapping screws to secure the lock-body to a 
sliding window, door or other member to be locked. Alternatively, the 
embodiment may only have the first hole 54 if an adhesive or other 
securing means is utilized. A truncated surface 53 in the top of the 
circular plate aligns in parallel with the open truncated plane of the 
C-shaped protrusion 48. A D-spring 46 is placed over the C-shaped 
protrusion 48 such that the D-spring 46 is against the front side and the 
straight portion of the D-spring forms a secant across a portion of the 
primary hole 54. 
An elongated hollow cylinder 44 is placed over the C-shaped protrusion 48 
forming a snug fit. 
A coil spring 38 which is slightly longer than the cylinder 44 is inserted 
into the cylinder 44 and abuts the end of the C-shaped protrusion 48. 
The preferred embodiment of the bolt 24 is shown in FIGS. 1 and 3. A planar 
surface 28 extends from the back end 30 to the first D-spring notch 26. 
The alternative embodiment of the bolt may have the first D-spring notch 
26 as shown in FIG. 2 without a planar surface. A second D-spring notch 20 
and a third D-spring notch 22 are positioned opposite each other near the 
approximate center of the bolt 24 offset approximately 90 degrees from 
positioned forward of the first D-sring notch 26 as shown in FIGS. 1 and 
3. An alternative embodiment may have only the second D-spring notch 20. 
The bolt 24 also has a circular spring retaining ring groove 16 positioned 
closer to the front end 12 than the second D-spring notch 20 and third 
D-spring notch 22 as shown in FIGS. 1 and 3. In FIG. 2 the alternate 
embodiment of the bolt provides a rigned protrusion 19 formed in the bolt 
around the circumference of the bolt to serve as the coil spring retaining 
means. The front end 12 of the bolt is beveled or rounded for easy 
insertion into holes. 
A spring retaining ring 18 is inserted into the spring retaining ring 
groove 16. 
The bolt 24 is inserted through the coil spring 38, cylinder 44, D-spring 
46, C-shaped protrusion 48 and plate of the lock body 50, such that the 
spring retaining ring 18 compresses the coil spring 38 biasing the bolt 24 
into the projected position thereby preventing the bolt 24 from being 
jiggled out of position even if the D-spring 46 is not engaged with the 
first D-spring notch 26. The spring retaining ring also forms a seal with 
the end of the cylinder 44 to prevent foreign matter from entering the 
cylinder 44. 
The handle 56 is securely fitted over the back end 30 of the bolt 24 which 
extends through the hole 54 in the plate of the lock body 50. The 
preferred embodiment of the handle 56 is cone shaped and has knurls 62 for 
positive gripping and a planar surface 58 on its top side which aligns in 
parallel with the planar surface 28 of the bolt 24 inserted within the 
shaped opening 60 to receive the back end 30 of the bolt. 
When the device is assembled in its preferred embodiment, the handle 56 is 
flush with the plate of the lock body 50, the D-spring 46 is engaged in 
the first D-spring notch 26, the spring retaining ring 18 compresses the 
coil spring 38 and forms a seal with the end of the cylinder 44, the front 
end 12 of the bolt 24 is projected beyond the cylinder 44 and the planar 
surface 28 of the bolt 24, the truncated surface 53 of the plate and the 
planar surface 58 of the handle 56 are all aligned in parallel. 
The bolt 24 cannot be retracted because the D-spring 46 is engaged in the 
first D-spring notch 26, thereby locking the bolt in its projected 
position. To retract the bolt 24, the handle 56 is rotated approximately 
90 degrees. This disengages thje D-spring 46. Retracting the handle 56 
until the D-spring 46 engages either the second D-spring notch 20 or the 
third D-spring notch 22 depending on which way the handle 56 was rotated. 
The bolt 24 has been retracted such that substantially the entire length 
of the bolt 24 is within the cylinder 44. To project the bolt 24 forward, 
the handle 56 is rotated in reverse through 90 degrees so that the planar 
surface 58 is on the top in alignment with the truncated surface 53. The 
spring 38 will bias the bolt 24 into the projected position. The D-spring 
46 will automatically engage the first D-spring notch 26. 
The requirement that the handle 56 first be rotated makes it more difficult 
for burgulars to defeat the device using burgular tools. 
The biasing of the bolt 24 into the projected position by the coil spring 
38 will maintain security even if the D-spring 46 is not engaged with the 
first D-spring notch 26. 
The device is essentially child proof. The handle 56 must be properly 
rotated and then retracted until the D-spring 46 engages either the second 
D-spring notch 20 or the third D-spring notch 22 before the bolt 24 will 
remain retracted. If the rotation does not properly align D-spring 46 with 
either the second D-spring notch 20 or third D-spring notch 22 or the 
handle 56 is not retracted far enough, the spring will bias the bolt 24 
into the projected position. 
The coding of the handle makes the device easy to use for someone knowing 
the code when the window or sliding door must be unlocked quickly or if a 
blind person wishes to use the device. 
In FIGS. 4, 5 and 6, to install the device on a vertically double hung 
window, an optional striker plate 70 is secured to the inside lower right 
or left side corner of the outside window sash 82. With the window in its 
closed position, a hole is drilled through the corresponding top right or 
left side corner of the inside window sash 80 (forming hole 86) through 
the striker plate 70 and partially into the outside window sash 82 
(forming hole 84A). The automatic bolt lock device is inserted into the 
hole with the cylinder 44 in the inside sash hole 86 such that the plate 
of the lock body 50 is flush with the inside window sash 80 and the 
truncated surface 53 is on top. The lock body 50 is secured in this 
position preferably by screwing into the sash. The front end 12 of the 
bolt 24 projects through the striker plate 70, into the outside window 
sash hole 84A, locking the window closed. 
A second hole 84B can be drilled above the first hole 84A through the 
striker plate 70, partially into the outside window sash 82. The window 
can then be locked into a partially opened position to allow ventilation 
yet maintain security. 
The automatic bolt lock device 50 may similarly be installed in a 
horizontal double hung sliding window or a sliding door 88 and 89 as in 
FIG. 7, also utilizing a series of holes 84 in a striker plate 70C. 
In FIG. 8, the automatic bolt locking device 50 is used to lock an 
adjustable shelf 90 into place by securing a device 50 through each of two 
ends of a support bracket 92. Adjustability is provided by securing the 
device in each of a series of horizontally aligned pairs of holes 84 in 
striker plates 70D secured in parallel vertical alignment to a wall or 
vertical end support for a bookcase. 
Preferably the bolt 24 is fabricated of hardened steel, the springs are 
spring steel and the other components are molded plastic or steel. The 
device can be made in various sizes with various length bolts to suit the 
desired application. 
It is understood that the preceding description is given merely by way of 
illustration and not in limitation and that various modifications may be 
made thereto without departing from the spirit of the invention as 
claimed.