Door lock with locking pin

A door lock comprising a first thin plate having connecting channels secured to the side wall of the door jamb and a second thin plate having corresponding connecting channels secured to the side wall of the door adjacent its swinging edge in position for registration of its connecting channels with those of the first thin plate when the door is in its closed position. A locking pin is received through the connecting channels of both plates when they are brought into registration with each other to thereby hold the door in its closed position until the locking pin is withdrawn. The outwardly facing surface of the first plate secured to the door jamb and the surfaces of its connecting channels which face toward the swinging edge of the door when in its closed position are preferably coplanar to prevent those surfaces of the first plate's connecting channels from protruding into the swinging path of the door as it is opened and closed. The connecting channels may be cylindrical in cross-section to receive a cylindrical pin. They may also be angular in cross-section to received a pin of corresponding angular cross-section such as square or triangular. Selected ones of the connecting channels may have a different cross-sectional configuration than adjacent ones, and the locking pin may have correspondingly configured cross-sectional segments to require precise alignment by pre-determinable rotation of the locking pin to insert and withdraw. The locking pin can thereby not be withdrawn without knowing how to properly rotate for the correct alignment.

BACKGROUND OF THE INVENTION 
This invention relates to the field of door locks, and particularly of the 
kind sometimes known as security locks which can only be reached for 
locking and unlocking from one side of the door. 
Prior art devices of this kind include those disclosed in the following 
United States patents called to the inventor's attention during 
prosecution of Ser. No. 151,640: 
U.S. Pat. No. 4,015,868 discloses a lock assembly having a pair of hinge 
plates connected by a cylindrical hinge pin. The connecting channels of 
the plate secured to the wall of the door jamb protrude part way into the 
swinging path of the door to prevent opening and closing without damage to 
the door. 
U.S. Pat. No. 4,627,651 discloses a strike plate and face plate of a door 
lock in which both have apertures which come into registration when the 
door is closed to receive a lock bolt. 
U.S. Pat. No. 2,038,462 discloses a door latch having a construction which 
makes it useable with either right-hand or left-hand doors. 
U.S. Pat. No. 4,013,311 discloses a lock with a crossbar mounted on a door 
and a keeper mounted on the door frame, having a pin to extend through 
slots in spaced apart ears of the keeper to seat in a groove of the 
crossbar received between the spaced apart ears of the keeper. 
Door locks of the kind known to the proir art are relatively complex or 
they present problems when put in use, such as the one shown in U.S. Pat. 
No. 4,015,868 which has connecting channels that protrude part way into 
the swinging path of the door to prevent opening and closing without 
damage to the door. 
The door lock in accordance with the present invention overcomes such 
problems by providing a lock assembly of simplified construction, 
comprising two plates having interlocking channels in which the 
interlocking channels are constructed and positioned entirely out of the 
swinging path of the door. 
The door lock in accordance with this invention comprises a first thin 
plate for securing to the jamb or upright side wall of a door frame and 
which is sandwiched between the outer swinging edge of the door and the 
door jamb when the door is closed, and a second similar thin plate for 
securing to the side wall of the door adjacent its outer swinging edge to 
align with said first plate when the door is closed. 
The first thin plate has a first pair of spaced apart connecting arms 
extending out from the plate secured to the door jamb in the direction the 
door opens, the first pair of connecting arms terminating just beyond the 
door jamb in respective closed loops defining a first pair of axially 
aligned connecting channels. 
The second thin plate has a second pair of spaced apart connecting arms 
extending out from this plate secured to the door in the direction toward 
the first pair of spaced apart connecting arms of the first thin plate 
when the door is in its closed position, the second pair of spaced apart 
connecting arms terminating just beyond the outer swinging edge of the 
door in respective closed loops defining a second pair of axially aligned 
connecting channels. 
The uppermost connecting arms of one of the plates is received in the space 
between the connecting arms of the other of the connectable plates, and 
the lowermost connecting arm of the latter plate is received in the space 
between the connecting arms of the former plate, when the door is in its 
closed position. At such time, the connecting channels of all four 
connecting arms are axially aligned to provide a through channel to 
receive a locking pin. When the locking pin is inserted through the 
axially aligned connecting channels of all four of the connecting arms, 
the first and second plates are meshed and interlocked together to lock 
the door on which the second plate is secured to the door jamb on which 
the first plate is secured. 
Each plate has three apertures to receive mounting screws therethrough to 
secure the first plate to the door jamb and to secure the second plate to 
the door. 
The connecting channels of each connecting arm may all be cylindrical in 
cross-section to receive a locking pin of cylindrical cross-section. In 
the alternative, the connecting channels may be angular in cross-section 
to receive a locking pin of corresponding angular cross-section such as 
square or triangular. In a further alternative, selected ones of the 
connecting channels may have a cylindrical, square or other cross-section, 
and the locking pin may have a limited longitudinal portion of the same 
corresponding cross-section to pass through such selected one of the 
connecting channels after which the pin may be rotated out of alignment 
with such selected one of the connecting channels having the particularly 
configured cross-section. Two of the alternatively spaced apart connecting 
channels may have particularly configured cross-sections matching the 
cross-sections of two spaced apart longitudinal portions of the locking 
pin, whereby when the pin is positioned in only one pre-determined radial 
position its particularly configured cross-sections lines up with the 
particularly configured cross-sections of the alternatively spaced apart 
connecting channels so the locking pin can be inserted. The intervening 
connecting channels between those having the particularly configured 
cross-sections have an enlarged cross-section to permit rotation of the 
portion of the locking pin having the particularly configured 
cross-section when received in said intervening connecting channels. Thus, 
the locking pin can be rotated to rotate its particularly configured 
cross-sectional portions out of alignment with their respective connecting 
channels having the particularly configured cross-sections, thereby 
locking the locking pin in its interlocking position, interlocking both 
first and second plates together and the door to the door jamb. The 
locking pin cannot be removed and the door unlocked until the locking pin 
is rotated to the specific pre-determined radial position wherein the 
particularly configured cross-sectional portions of the pin and connecting 
channels are in alignment for withdrawal of the pin. 
In another alternative, the leading insert end of the pin has a 
particularly configured cross-sectional configuration, such as square, and 
each alternative one of the inter-meshed connecting channels has a 
corresponding square cross-section but positioned relative to each other 
at different radial positions whereby the locking pin has to be rotated to 
one radial position to pass through a first one of such connecting 
channels, then being received in the enlarged cross-section of an adjacent 
connecting channel where it can be rotated to a second radial position for 
alignment with the next connecting channel having the particularly 
configured cross-section. 
This construction protects against someone gaining entrance by breaking a 
hole through the door big enough to reach a hand through for withdrawal of 
the locking pin, or breaking the glass in doors having windows. The 
locking pin cannot be removed unless it is rotated into the specific 
pre-determined radial position, or series of different radial positions 
required for withdrawal. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a door lock of simplified 
construction and easy to install, comprising two lockable plates each 
having a pair of spaced apart interlocking connecting channels for axial 
alignment when in the locking position and a locking pin receivable 
therein to lock the two plates together, the interlocking connecting 
channels being constructed and positioned entirely out of the swinging 
path of the door to which one of such plates is secured. 
It is an object of the invention to provide a door lock comprising two 
lockable plates each having a plurality of spaced apart interlocking 
connecting channels for axial alignment when in the locking position to 
receive a locking pin therethrough, and means to prevent withdrawal of the 
locking pin until rotated to a particular radial position. 
It is an object of the invention to provide a door lock comprising two 
lockable plates each having a plurality of spaced apart interlocking 
connecting channels for axial alignment when in the locking position to 
receive a locking pin therethrough, wherein the connecting channels have 
an angular cross-sectional configuration.

DESCRIPTION OF PREFERRED EMBODIMENT 
A door lock in accordance with the present invention comprises a pair of 
metal plates having interlocking members, including a first plate 2 for 
securing to the door jamb 4 or upright wall of a door frame 6 and a second 
plate 8 for securing to the door 10 which is to be locked when the door is 
closed and the two metal plates 2 and 8 are brought together. At such 
time, the interlocking members 12 of the first plate 2 mesh with the 
interlocking members 14 of the second plate 8, and the interlocking 
channels 16 through interlocking members 12 of the first plate 2 are 
axially aligned with the interlocking channels 18 through interlocking 
members 14 of the second plate 8. A locking pin 20 is then inserted 
through the aligned interlocking channels 16 and 18 to lock the door in 
its closed position. 
The first metal plate 2 comprises a body portion 22 of thin metal which can 
be sandwiched between the door jamb 4 and the outer swinging edge 24 of 
the door 10. The interlocking members 12 of the first plate 2 comprise a 
pair of spaced apart connecting arms 26 and 28 which extend outwardly from 
the connecting edge 30 of metal plate 2, and terminate in respective 
closed loops 32 and 34 which bound and define the interlocking channels 16 
of the first plate 2 which are axially aligned with each other. The first 
plate 2 includes a pair of apertures 36 through the body portion 22 to 
receive wood screws 38 therethrough to secure the first plate 2 to the 
door jamb 4. 
The second metal plate 8 comprises a body portion 40 of thin metal 
comparable in thickness to that of body portion 22 of metal plate 2. The 
interlocking members 14 of the second plate 8 comprise a pair of spaced 
apart connecting arms 42 and 44 which extend outwardly from the connecting 
edge 46 of the metal plate 8, and terminate in respective closed loops 48 
and 50 which bound and define the interlocking channels 18 of the second 
plate 8 which are axially aligned with each other. The second plate 8 
includes three apertures 52 through the body portion 40 to receive wood 
screws 38 therethrough to secure the second plate 8 to the side wall 54 of 
the door 10 adjacent its outer swinging edge 24, at a point thereon which 
brings the interlocking members 14 of the second plate 8 into interlocking 
engagement with the interlocking members 12 of the first plate 2 when the 
door 10 is moved to its closed position. 
The connecting arms 26 and 28 of the first plate 2 and their respective 
closed loops 32 and 34 are spaced apart a distance corresponding to the 
longitudinal dimension of the connecting arms 42 and 44 of the second 
plate 8 and of their closed loops 48 and 50, whereby closed loop 48 of the 
second plate 8 is snugly received in the space 54 between closed loops 32 
and 34 of the first plate 2, and closed loop 34 of the first plate 2 is 
snugly received in the space 56 between closed loops 48 and 50 of the 
second plate 8. 
The outwardly facing surface 58 of the body portion 22 of plate 2 and the 
outwardly facing surface 60 of the connecting arms 26 and 28 of plate 2 
are coplanar, whereby the closed loops 32 and 34 of plate 2 are positioned 
to one side of the swinging path of the door 10 when it is moved between 
its open and closed positions. The closed loops 32 and 34 of plate 2 do 
not protrude into the swinging path of the door 10, whereby the outer 
swinging edge 24 of the door 10 is able to clear the closed loops 32 and 
34 and cannot be damaged as happens with prior art devices in which 
corresponding connecting loops protrude into the swinging path of the door 
when the plate they extend from is secured to the door jamb surface which 
faces the outer swinging edge of the door in its closed position. 
The cross-sectional configuration of the interlocking channels 16 of plate 
2 and interlocking channels 18 of plate 8 may be circular or cylindrical, 
and in such case the cross-sectional configuration of the locking pin 20 
is also circular or cylindrical. 
The cross-sectional configuration of the interlocking channels 16 of plate 
2 and interlocking channels 18 of plate 8 may in the alternative be 
angular, such as square or triangular, in which case the cross-sectional 
configuration of the locking pin 20 is also angular, such as square or 
triangular respectively. 
In a modification of the invention, the interlocking channels 160 and 180 
and the locking pin 220 are constructed so that the locking pin 220 has to 
be rotated to a pre-determined radius of rotation in order to be inserted 
and withdrawn, or rotated to a plurality of pre-determined radii during 
insertion and withdrawal. 
FIG. 10 illustrates a modified first plate 200 in a top plan view in which 
the interlocking channel 160 of the upper closed loop 320 has a square 
cross-section bounded by four straight side walls 322 of equal dimension. 
The spaced apart lower closed loop 340 is not visible in the top plan view 
of FIG. 10 but portions of its four straight side walls 342 which bound 
its interlocking channel 162 are visible. The four straight side walls 342 
of lower closed loop 340 are of equal dimension and define a square 
cross-section of interlocking channel 162. The side walls 322 of closed 
loop 320 and the side walls 342 of closed loop 340 are of equal dimension, 
and interlocking channels 160 and 162 have square cross-sections of equal 
dimension. The square cross-section channels 160 and 162 are axially 
aligned, but the side walls 342 of interlocking channel 162 are 
rotationally offset from the side walls 322 of interlocking channel 160 as 
can be seen in FIG. 10. 
The modified locking pin 220 shown in FIG. 11 includes an elongated shank 
222 having an enlarged portion 224 of square cross-section corresponding 
in configuration and dimension to that of the interlocking channels 160 
and 162. The longitudinal dimension of the enlarged square cross-section 
portion 224 is less than the corresponding longitudinal dimension of the 
space 54 between the upper closed loop 320 and the lower closed loop 340 
of the modified first plate 200. 
The cross-sectional dimension of the enlarged square cross-section portion 
224 of the modified locking pin 220 is smaller than the circular 
cross-sectional dimension of the interlocking channel 18 of the upper 
closed loop 48 of the second plate 8, whereby when the enlarged portion 
224 of locking pin 220 reaches the interlocking channel 18 of closed loop 
48 as it is being inserted and withdrawn it can be rotated to rotate the 
square cross-section portion 224 to any desired radius of rotation. 
When inserting the modified locking pin 220 to lock the modified plate 200 
secured on the door jamb 4 to the plate 8 secured on the door 10 when in 
its closed position, the walls of the square cross-section portion 224 are 
aligned with the walls 322 of square cross-section channel 160 of the 
upper closed loop 320 of the modified plate 200. The locking pin 220 is 
then inserted until its square cross-section portion passes into the 
circular interlocking channel 18 of the upper closed loop 48 of the plate 
8, at which time the locking pin 220 is rotated to a pre-determined radius 
wherein the walls of its square cross-section portion 224 become aligned 
with the walls 342 of the square cross-section interlocking channel 162 of 
the lower closed loop 340 of the modified plate 200. The locking pin 220 
is then inserted further, passing its square cross-section portion 224 
through the interlocking channel 162 and into the circular interlocking 
channel 18 of the lower closed loop 50 of the plate 8. 
The modified locking pin 220 terminates in a short stub 226 of circular 
cross-section and smaller dimension than that of the square cross-section 
portion 224, to seat in a lower end recess portion 182 of corresponding 
cross-sectional configuration and dimension, such lower end recess portion 
182 being formed as an extension of the lower closed loop 50 of plate 8 
for use with the modified plate 200 and modified locking pin 220. The 
lower end recess portion 182 holds the stub 226 of the modified locking 
pin 220 snugly in place. 
The modified locking pin 220 can be rotated when fully inserted to rotate 
its square cross-section portion 224 out of alignment with the square 
cross-section locking channel 162. The modified locking pin 220 cannot now 
be withdrawn, but is locked in place until rotated to the pre-determined 
radius of rotation wherein the square cross-section portion 224 is again 
aligned with the square cross-section interlocking channel 162. The 
locking pin 220 can then be withdrawn until its square cross-section 
portion 224 reaches the circular cross-section interlocking channel 18 of 
the upper closed loop 48 of the plate 8. The locking pin 220 now has to be 
rotated again to a second pre-determined radius of rotation to align its 
square cross-section portion 224 with the square cross-section of 
interlocking channel 160 of the upper closed loop 320 of the modified 
plate 200, before it can be fully withdrawn to unlock the door 10. 
The modified locking pin 220 as shown in FIG. 11 also includes an annular 
collar 228 at its upper end region to seat in a corresponding annular 
recess 164 of the upper closed loop 320 of the modified plate 200. Thus, 
when the modified locking pin 220 is fully seated in the interlocking 
channels, the projecting stub 226 received in the recess 182 at the lower 
end and the annular collar 228 received in the annular recess 164 at the 
upper end holds the modified locking pin 220 in stable axial alignment 
within the interlocking channels. 
The pin locking construction described herein utilizes cross-sections 
having a square configuration for the respective alternating channels and 
for the relevant portion of the locking pin. A wide variety of specially 
designed cross-sectional configurations may be used which are other than 
circular, or which are non-circular. The respective cross-sections of the 
relevant parts can simply have a radially enlarged segment, such as an 
oval shape, or circular but with a single radial extension such as a 
radially projecting lug on one part, such as the pin, and radially 
projecting recess in the shape of such lug on the other corresponding 
part, such as the receiving channel.