Lock mechanism

A lock mechanism is disclosed in which a hollow cylindrical housing is provided with at least one interior longitudinal slot. A cylinder having a longitudinal keyway is inserted into the housing and an endpiece having at least one radial groove and one circumferential groove is attached to the housing. At least one tumbler is pivotably mounted within the cylinder on an axis transverse to the cylinder. The tumbler has a locking edge sized and positioned to extend into the longitudinal groove in the housing when the tumbler is in a locked position and to be within the cylinder when the tumbler is in an unlocked position. The tumbler also has a tab sized and positioned so as to fit within the radial groove of the endpiece when the tumbler is in a locked position, and to align with and be capable of traveling through the circumferential groove of the endpiece when the tumbler is in an unlocked position. A keying edge is provided on the tumbler which has a given slope relative to a center line through the keyway and which extends into the keyway. The tumbler is spring biased to a locked position. It is moved to an unlocked position by the insertion of a key having a surface which is oriented and sloped to engage the keying edge of the tumbler and rotate the tumbler to an unlocked position.

FIELD OF INVENTION 
The invention relates to key operated lock mechanisms to restrict access to 
a room, area or container. My lock mechanism is primarily intended for use 
on doors, but it can be adopted for other applications. 
DESCRIPTION OF THE PRIOR ART 
There are dozens of key operated lock mechanisms which have been developed 
in the past. The most common employs tumblers and a key having a series of 
teeth cut into one edge. 
The key is inserted into the lock. If the teeth are in proper alignment 
with the tumblers one can turn the key which moves the tumblers and 
releases the lock mechanism. This type of lock is relatively easy to pick. 
Therefore, efforts have been made to develop other lock mechanisms which 
are more secure. 
Moorhouse in U.S. Pat. No. 4,073,171, issued Feb. 14, 1978, discloses a 
lock device having a plurality of rotatable cylindrical drums each having 
a latching member and one or more tumblers attached. The device is 
operated by a key comprised of a rod having pairs of radially extending 
flanges. When the key is inserted into the lock mechanism each pair of 
flanges is aligned with one of the rotatable cylinders. When the key is 
turned, the flanges engage and release the tumblers and turn the 
cylinders. The lock will release when all of the cylinders are aligned 
with one another. Although this lock device may be more complicated, it is 
still capable of being picked without undue difficulty, Because it is more 
complicated, this lock would be more difficult to manufacture than the 
common key locks. It would, therefore, be significantly more expensive. 
Another lock mechanism, known as the Bramah lock, contains locking levers 
or cranks pivotably mounted about transverse axes which pivot into a 
completely unlocked state when a key is completely inserted. In this type 
of lock the key is formed so that when it is inserted it will cooperate 
with the nose of the levers and together with the levers function as 
tumblers. Guiraurd discloses one version of the Bramah lock in his U.S. 
Pat. No. 4,196,606, issued Apr. 8, 1980. Guiraurd proposes that horizontal 
and vertical tabs be cut at one end of the lever which will align with a 
housing only when the key is inserted. When the key is removed the tabs 
will move out of alignment and the lock mechanism will not turn. The 
Bramah lock is comprised of substantially more pieces than conventional 
key locks and is, therefore, more difficult and expensive to manufacture. 
Furthermore, the number of lock combinations are limited. 
SUMMARY OF THE INVENTION 
I have invented a lock mechanism with double locking capability which can 
be made with an almost infinite number of combinations. The lock is 
virtually pick-proof and can be readily manufactured at a relatively low 
cost. 
I prefer to provide a substantially solid cylinder having a longitudinal 
bore through its center and at least one radial slot. A tumbler is 
pivotally mounted in each slot on transverse axes. The tumbler is shaped 
so that when in a locked position it will project out of the cylinder and 
fit with a slot cut in a housing that surrounds the cylinder. When a key 
is inserted it will engage an edge of the tumbler and cause it to rotate. 
Rotation of the cylinder will cause a dead bolt or spring bolt to release 
or will create an electrical contact which will cause the door or 
container to open. The amount of tumbler rotation will depend upon the 
mating edges of the key and tumbler. These edges can be cut so that 
insertion of the key will cause the tumbler to rotate far enough so that 
it will no longer extend into the slot in the housing. A spring on the 
tumbler will cause the tumbler to return to its original locked position 
when the key is removed. The combination of my lock will depend upon the 
number of tumblers, the position of those tumblers relative to radii 
extending from the central bore, and the shape of the tumbler. 
To provide double locking capability I prefer to provide a tab on each 
tumbler that extends from the tumbler to the exterior of the cylinder. I 
provide an endpiece which fits over the end of the cylinder into which the 
tumbler tabs extend. Each tab fits in a radial slot cut in the endpiece. I 
also provide circumferential grooves in the endpiece which are sized and 
positioned so that each tumbler tab will be aligned with a circumferential 
groove when the tumbler is in an unlocked position. When the tumbler is in 
the unlocked position, the tumbler tab can travel through the 
circumferential groove as the cylinder is turned. When the tumbler is 
locked each tab will be in a radial groove but not aligned with its mating 
circumferential groove. Hence, the cylinder cannot rotate. 
Other details, objects and advantages of the invention will become apparent 
as a description of a present preferred embodiment of the invention 
proceeds.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
My lock mechanism has five basic components: a cylinder, housing, endpiece, 
tumblers and a key. A present preferred embodiment of the cylinder is 
shown in FIGS. 1, 3, and 4. The cylinder 2 is a substantially cylindrical 
solid having a longitudinal central bore 4 and at least one radial slot 6 
into which a tumbler 12 shown in FIG. 2 is inserted. The tumbler is held 
in place by a pin 9 passing through a transverse bore 10. As can be seen 
from FIGS. 1 and 2, pin 9 will pass through hole 13 in the tumbler 12 
which is sized to permit the tumbler to pivot around pin 9. A post 14 is 
provided on the face of the tumbler 12 which provides a seat for spring 
clip 16. One end 16a of the spring clip 16 will fit into groove 15 cut 
into post 14. Secondary slots 8 are cut in cylinder 2 to provide clearance 
for the post 14 and spring 16. When the tumbler 12 is fitted into the 
cylinder one end 16b of spring 16 will press against a side 8a of groove 8 
to hold the tumbler in a locked position, as shown in FIG. 5. 
Referring now to FIGS. 5 and 8, the cylinder 2 is inserted into a housing 
20 where it is held in place by a clip 22. The clip 22 is inserted through 
a slot 24 in the housing 20 until it engages a groove 7 cut in the 
cylinder. The housing 20 is a hollow cylindrical body 21 having a face 
plate 26 at one end. The face plate 26 is of somewhat greater diameter to 
provide a flange 25 which acts as a stop when the lock mechanism is 
inserted into a door. A keyhole 27 is cut in the center of the face plate 
26 and is in alignment with bore 4 in the cylinder. I prefer to provide 
sloping sides on the keyhole to make key insertion easier. Grooves 28 are 
cut along the inner surface of the housing 20 to accommodate tumblers 12. 
When the tumblers 12 are in a locked position, they will protrude into 
groove 28 preventing the cylinder 2 from rotating relative to the housing 
20. Finally, threaded holes 29 are cut in the end of the housing to 
receive screws which hold the endpiece in place. The endpiece 30, shown in 
FIGS. 6 and 7 is generally cylindrical having a diameter larger than the 
housing body 21. At least one substantially radial groove 32 is cut in the 
face of the endpiece 30. These grooves are sized and positioned to receive 
a tab 31 which protrudes from the tumblers (see FIG. 2). One may choose to 
use a single tab as shown in FIGS. 2, 5 and 9, or one may use two or more 
tabs as shown in FIGS. 10 and 11. As the tumbler pivots, the tab 31 can 
move through this groove 32. I also provide one or more circumferential 
grooves 33, 34 and 35 in the face of the endpiece 30. When the tumbler is 
in an unlocked position tab 31 will line up with one of these grooves and 
travel through the groove when the cylinder 2 is rotated relative to the 
housing 20. Tab 31 will not align with a circumferential groove when the 
tumbler is in a locked position. Being out of alignment, the tab will 
prevent the cylinder from rotating relative to the housing. The endpiece 
30 is attached to the housing 20 by screws which pass through holes 39. 
The operation of my lock mechanism can be best understood by referring to 
FIGS. 9 through 13. In FIG. 9 I show a tumbler 12 in a locked position and 
a second tumbler 112 shown in chain line in an unlocked position. It is to 
be understood that a single tumbler would pivot from the unlocked position 
of tumbler 112 to the locked position of tumbler 12. In the locked 
position a portion 121 of tumbler 12 extends into groove 28 of housing 20. 
In addition, tab 31 does not align with any of the circumferential grooves 
33, 34 or 35 in the endpiece 30. When a key 40 whose end is shown in chain 
line in FIG. 9 is inserted, face 42 of the key engages edge 122 of the 
tumbler. As the key is pushed into the lock, tumbler 12 will turn to an 
unlocked position shown by tumbler 112. In this position the tumbler no 
longer protrudes into gap 28 as portion 121 has moved to point 121a. Tab 
31 has moved to tab 31a and is in line with circumferential groove 33. 
When the key is removed the tumbler will return to its original position. 
The amount by which the tumbler rotates is determined by the slope of 
tumbler edge 122 and the slope of key face 42. If the slopes do not match, 
tumbler 12 will rotate too much or too little. In either event, tab 31 
would not align with a circumferential groove, or point 121 will be in 
slot 28 of the housing 21 or both will happen. 
FIGS. 10 and 11 are sectional views similar to FIG. 4 showing a pair of 
tumblers having two tabs in locked and unlocked positions. Referring to 
these figures, tumblers 211 and 212 are fitted over pins 9 that pass 
through cylinder 2. A spring clip 216 is fitted around pin 209 and is 
seated at one end in clip support 214. The other end of the clip rests 
against the edge 8a of slot 8 shown in chain line over tumbler 211 and in 
dotted line when it is covered by tumbler 212. Two tabs 230 and 231 
project from tumblers 211 and 212 into radial lot 32 in endpiece 30. 
Endpiece 30 has two circumferential grooves 33 and 34. When the tumblers 
are in a locked position the tabs 230 and 231 will not be aligned with the 
circumferential grooves and the tumbler will extend into slot 28 of 
housing 20. The tumblers are activated by a key 40 which is inserted 
through keyway 4. The key is cut to have sloped surfaces 42 and 44 which 
will engage edges 242 and 244 of tumblers 211 and 212. For the tumblers 
shown in FIG. 10 to reach the unlocked position shown in FIG. 11, they 
must rotate 25.degree.. In the locked position edges 242 have a slope of 
35.degree. from the horizontal and edge 244 is sloped at 40.degree. from 
the horizontal. To achieve a 25.degree. rotation of both tumblers 211 and 
212, key face 42 must have a slope of 10.degree. and key face 44 must have 
a slope of 15.degree.. When the key 40 is fully inserted tumblers 211 and 
212 will have moved to an unlocked position. When the key 40 is removed 
spring clip 216 will return the tumblers back to a locked position. To 
prevent the tumblers from rotating too far when the key is removed the 
radial groove 32 can be cut so that tab 231 will rest against the bottom 
edge 232 of the groove when the tumbler is in a locked position. 
I prefer to provide four tumblers in my lock mechanism as indicated by 
FIGS. 1 and 3. Such an arrangement would require a key like that shown in 
FIG. 12. One end of the body 41 of the key 40 has four sloped surfaces 42, 
43, 44 and 45 each of which engage a tumbler. A handle 46 is attached to 
the opposite end of the body. A notch 48 or other marking is provided to 
indicate the proper orientation of the key when it is inserted into the 
shaft. I prefer to make the body 41 of the key 40 substantially 
rectangular; however, other shapes could be used. Although I have shown a 
key with flat edges, grooves could be cut along the body 41 to accommodate 
teeth projecting into the keyhole or keyway. One could also choose to use 
more or less than four tumblers. No matter how many tumblers are used, 
there must be a mating surface on the end of the key oriented to engage 
each tumbler. Each surface would have a slope compatible with the edge of 
the tumbler. 
For a given embodiment of my lock mechanism there are several ways to 
change the combination. First, one could change the radial orientation of 
the tumblers relative to the cylinder's longitudinal bore. Second, one 
could change the slope on the edge of the tumbler which mates with the 
key. Third, one could change the position of the tabs and circumferential 
grooves in the endpiece. Finally, one could also change the size of any 
component. The possible permutations of these factors are tremendous. 
Hence, hundreds of my locks could be made so that no two of them are 
exactly alike. 
Another advantage of my lock mechanism is that the tumblers are free to 
rotate past the unlocked position. If that occurs the cylinder will not 
turn. It is, therefore, extremely difficult to pick my lock with a hairpin 
or other object. 
Those skilled in the art will recognize that my lock could be adapted to 
operate a variety of dead bolts and spring locks, or could be used to 
activate an electrical mechanism. In FIGS. 10, 11 and 13, I illustrate one 
possible way in which my lock mechanism could be used. As shown in those 
Figures, I provide a stub shaft 250 which extends from cylinder 2 through 
a hole 251 in endpiece 30. This shaft would be generally round with a flat 
surface 252. A tab 254 is fitted over the shaft 250 to activate a bolt or 
to otherwise serve to lock and release a door or container. This 
arrangement could also be adapted for an electrical lock by making tab 254 
of a nonconductive material and applying a strip of solder across it. An 
end cap (not shown) would be fitted over tab 254. This end cap would 
contain two or three contact points which would abut the solder strip to 
complete a circuit when the tab 254 is in an unlocked position. The 
contacts would not touch the solder strip when tab 254 is in a locked 
position. Tab 254 is held in place by a screw 256 which fits into a screw 
hole through the center of shaft 250. 
While I have shown certain present preferred embodiments of my invention, 
it is to be distinctly understood that the invention is not limited 
thereto but may be variously embodied within the scope of the following 
claims.