Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to locks wherein spring-biased pins extend between a housing and a rotatable barrel member when the barrel is in a locked position to prevent rotation, and more particularly to such a lock wherein the pins are moved against their biasing springs to allow rotation of the barrel to an unlocked position by magnetic means.
2. Prior Art
Conventional pin and cylinder locks employ a plurality of cavities formed in a housing to extend radially from the axis of rotation of a cylinder supported in the housing. The cylinder is formed with a line of apertures that mate with and extend from the ends of the apertures in the housing when the cylinder is in the locked position. Pins are supported in these apertures and are biased by springs contained in the housing so that they extend into the cylinder to various lengths when the cylinder is in its locked position. A key insertable into a hole in the cylinder has a plurality of lobes of varying height which abut the ends of the pins to push them into positions where they do not extend between the housing and the cylinder and allow rotation of the cylinder through the key.
Over the years, a number of devices and techniques have been developed to "pick" these locks without use of a key. These locks generally afford little protection against professional burglars and the like
To complicate the task of picking these locks, structures have been proposed wherein the pin apertures are not all aligned axially but are disposed at different radial angles to the barrel. Also, lock structures have been proposed wherein the pins are magnetized and the key consists of a member for supporting a plurality of magnets in the keyhole which will repel certain of the magnetic pins and attract others to move t them into an unlocked position.
These magnetic pin locks have not gained wide commercial acceptance. Among the reasons for this lack of success is the fact that these locks can be picked in a manner similar to mechanical pin locks through use of some appropriate master key-like structure, possibly associated with an adjustable electrical power source for varying the sense of the various magnets. One of the central disadvantages of all pin locks, be they mechanical or magnetic, is the orientation of the pins about a central keyhole which provides a reference location for the application of mechanical or magnetic forces to pick the lock.
SUMMARY OF THE PRESENT INVENTION
The present invention is directed to magnetic pin lock which does not employ a keyhole or any other reference line which may be used to apply magnetic forces to the lock to pick it. Rather, locks formed in accordance with the present invention are opened by the application of magnetic forces of the proper sense applied at a plurality of locations distributed over a two-dimensional surface. In the preferred embodiment of the invention this surface forms an extension of the door or wall surface in which the lock is supported. In order to pick this lock, it is necessary to establish the location of the magnetic pins behind the two-dimensional surface, and the magnetic sense of such pins. While such a lock may be "pickable" it certainly would be much more difficult to pick than any conventional lock structure employing pins arrayed about a central keyhole.
A preferred embodiment of the present invention takes the form of a rotatable cylinder or barrel disposed within a housing. The barrel is connected to a conventional latch mechanism so that when the barrel is in position of rotation coincident with the lock position, the door may not be opened but when the barrel is rotated to its unlocked position the door may be opened. The section of the barrel projecting from the housing is cylindrical and has its end flush with the surface of the housing. A shoulder is formed in the barrel behind the wall surface and the housing has a contiguous surface extending normally to the axis of rotation of the barrel which abuts this shoulder. A number of pin-holes or apertures extend into both the barrel and the housing from this pair of contiguous surfaces. The holes extend normally to the surfaces and parallel to the axis of rotation of the barrel and the pin holes in the barrel and housing are axially aligned when the barrel is in its locked position. The holes need not be positioned in any particular arrangement over the surfaces in which they are formed. They may be formed at different distances from the rotational axis of the barrel and at random distances with respect to one another.
Each set of holes formed by one aperture in the barrel and an aligned aperture in the housing have the same total length but some of the holes have a greater depth in the barrel while other of the holes have a greater depth in the housing.
An elongated cylindrical metal pin formed of a permanently magnetized material is disposed in each of these aperture sets. They have a length slightly shorter than the length of the deeper hole in each set and they have a diameter which allows them to freely slide within the apertures. A coil wire spring is disposed in the deeper aperture in each set so as to bias the pin toward a position outside of that aperture. Thus, when the barrel is in its locked position, the pins extend out of the longer aperture of each set and extend into the shorter aperture, bridging the gap between the abutting surfaces of the barrel and the housing. This prevents the barrel from being moved into an unlocked position relative to the housing.
The key for use with the lock preferably takes the form of a cylinder having a truncated face and containing bar magnets buried in its surface just beneath the face. These magnets correspond in position to the apertures in the barrel so that when the face of the key is brought into proper position with the exposed surface of the barrel magnets the key will tend to attract or repel the pins in the barrel, depending upon their relative polarities. The forces exerted will be such as to move the pins against the bias forces exerted by the springs to cause all of the pins to retract into the deeper aperture of each pair. In this position none of the pins bridge the gap between the barrel and the base and the barrel is free to rotate relative to the base to an unlocked position.
Once the key has been properly applied to the lock to force the pins against their springs so that the barrel is free to rotate relative to the base, the barrel may be rotated either through the key or through the imposition of a rotative force from an auxiliary mechanism such as a door handle. In the preferred embodiment of the invention, the key acts to rotate the barrel. The exposed cylindrical face of the barrel is slightly recessed relative to the adjoining surface of the base so that the cylindrical key may be placed within the recess to assure proper axial alignment. The key face has a shallow aperture which receives a stud projecting out from the exposed surface of the lock barrel at any point displaced from the central axis of the lock. Aligning the stud in the key aperture assures proper rotational alignment of the key with the lock. By rotating the key, a rotary force is transmitted through the stud to the barrel, allowing the barrel to rotate once the pins have been retracted.
While the cylindrical surface of the barrel to which the magnetic forces are applied extends from the housing in the preferred embodiment of the present invention, in an alternate embodiment a thin sheet of material covers the barrel. In such an embodiment alternate means must be provided for applying rotative forces to the barrel to open the door.
Locks formed in accordance with the present invention are therefore relatively simple in construction so as to be low cost and relaible in operation. The absence of any keyhole not only complicates the difficulty associated with picking the lock but makes the lock extremely useful in structures such as safes where the material surrounding the lock is intended to be drill and torch resistant and any apertures such as a keyhole makes it easier to break into the safe.
Other objectives, advantages and applications of the present invention will be made apparent by the following detailed description of a preferred embodiment of the invention. The description makes reference to the accompanying drawings in which:
FIG. 1 is a perspective view of a section of a door incorporating a lock formed in accordance with the present invention and illustrating the key being brought into position to open the lock;
FIG. 2 is a side view of the preferred embodiment of the lock;
FIG. 3 is a sectional view through the lock of FIG. 2 taken along line 3--3 of FIG. 2;
FIG. 4 is a sectional view of the lock taken along line 4--4 of FIG. 3, with the key in position to open the lock;
FIG. 5 is a sectional view of the lock and the key in a closely proximate but not unlocking condition, taken along line 4--4 of FIG. 3; and
FIG. 6 is a sectional view through the lock of FIG. 2 taken along line 6--6 of FIG. 3.
Locks formed in accordance with the present invention are typically employed as door locks for residential, commercial and industrial doors, safe doors, security box doors, as vehicle locks, or in any other situation where pin and cylinder locks have previously been employed.
FIG. 1 illustrates a broken section of a door 10 equipped with a lock formed in accordance with the preferred embodiment of the invention and a key for use with the lock. The lock is formed of a cylindrical housing or barrel 12 and a cylinder mechanism 14 rotatably supported within the housing. The housing 12 is preferably formed of plastic or a non-ferrous metal. It has a central cylindrical bore consisting of a small diameter section 16 and a large diameter section 18 which meet at an internal shoulder 20 extending in a plane normal to the central axis of the cylinder 12 about midway through its thickness.
The lock cylinder 14 is also formed of plastic or a non-ferrous metal and has a diameter complementary to that of the bore section 18 so that it is rotatably supported within the bore. The cylinder has an integrally formed cylindrical rod section 22 of a diameter complementary to the smaller bore section 16 which is rotatably supported within that section. The cylinder and the rod are connected by a shoulder 24 which abuts the shoulder 20 of the housing. The cylinder 14 has a thickness slightly shorter than the length of the large bore section 18 in the housing so that the end face 26 of the cylinder 14 is slightly recessed within the housing. A ring 28 seated in a groove formed in the rod 22 retains the cylinder 14 within the housing 12.
The cylinder 14 has four elongated cylindrical cavities 30, 32, 34 and 36 formed parallel to its central axis and opening onto the shoulder 24. The cavities 30 and 32 are relatively shallow in depth while the cavities 34 and 36 are substantially deeper. Four complementary cavities 38, 40, 42 and 44 are formed in the cylinder 14, extending parallel to its axis and opening onto the shoulder 24. These four holes are all of the same depth, dead-ending just short of the outer cylinder face 26 so that a thin wall of the cylinder material separates them from the face. The cavities 38, 40, 42 and 44 form linear extensions of the cavities 30, 32, 34 and 36 in the housing when the cylinder 14 is at a particular rotational position with respect to the housing which will be termed the "locked" position. Thus, the cavity 30 in the housing 12 and the complementary cavity 38 in the cylinder 14 form a single elongated cavity when the cylinder is in the locked position. Similarly, the cavity pairs 32 and 40, 42 and 34 and 44 and 36 formed single elongated cavities when the cylinder is in the locked position.
An elongated cylindrical bar magnet pin 46 is supported in the cavity set formed by the cavities 32 and 40. The magnet 46 is an elongated cylinder having a diameter slightly smaller than the diameters of the holes 32 and 40 so that it makes a loose sliding fit within them.
The magnet 46 has a truncated end and has a length slightly shorter than the length of the cavity 40. A thin wire coil spring 48 is disposed in the cavity 40 behind the magnet 46 so as to bias the magnet out of the cavity 40. Accordingly, when the cylinder 14 is in its locked position relative to the housing 12 the spring 48 urges the magnetic pin 46 out of the cavity 40 so that its end projects into the cavity 32 as illustrated in FIG. 5. The pin thus bridges the gap across the shoulders 20 and 24 and prevents rotation of the cylinder 14 relative to the housing 12.
A similar magnetic pin and a spring are disposed in the cavity set formed by the cavity 30 in the housing and the complementary cavity 38 in the cylinder.
Another magnetic pin 50 is supported in the cavity 44 formed in the cylinder 14. The pin 50 has a length slightly shorter than the depth of the cavity 44. It has a truncated end which abuts a similar pin 52 disposed partially in the cavity 36 and partially in the cavity 44 when the cylinder is in its locked position. The pin 52 is preferably not formed of a magnetic material. It has the same diameter as the pin 50 and is slightly shorter. A coil spring 54 is seated in the cavity 36 behind the pin 52 so as to urge the pin 52 to move against the pin 50 into the cavity 44. Accordingly, when the cylinder is in the locked position and the key is not in place, as illustrated in FIG. 5, one end of the pin 52 extends into the cavity 44, bridging the gap between the shoulders 20 and 24 and preventing rotation of the cylinder relative to the housing.
A set of pins and a spring similar to the pins 50, 52 and the spring 54 are also disposed in the cavity set 34, 42.
It should be noted that the cavity sets are displaced from the central axis of the lock by varying distances. Thus, the cavity set 30, 38 is the farthest displaced from the axis and the cavity set 34, 42 is the closest to the axis. In effect, these cavity sets may be formed at any points in the shoulder 20, 24 and it is generally desirable that they be formed at different distances from the central axis.
The key used with the lock of the preferred embodiment, generally illustrated at 60, consists of a cylindrical section 62 of non-ferrous material having truncated ends. A ring member 64 for use as a handle or for attachment to a key ring is affixed to one end of the cylinder. Four bar magnets 66 are embedded in the cylinder 62. The bar magnets are cylindrical in shape and each has one of its ends exposed on the interior face 68 of the cylinder 62. The bar magnets 66 are equal in number to the cavity sets formed in the cylinder and housing and the magnets 66 are positioned with respect to the central axis of the cylinder 62 in the same array as the cavities. The key 62 has the same diameter as the lock cylinder 14 allowing its face 68 to be inserted within the free extending section of the bore 18 so that the face 68 of the key is brought into abutment with the face 26 of the lock cylinder.
To achieve proper rotational alignment between the key 62 and the lock, a hole 70 is formed in the face 68 of the key and is adapted to engage a stud 72 projecting from the forward face 26 of the lock cylinder 14. When the key is inserted within the bore 18 so that the stud 72 mates with the hole 70 in the manner illustrated in FIGS. 4 and 6, the ends of the magnets 66 are in close proximity to the ends of the pins disposed in the cylinder cavities 38, 40, 42 and 44, being separated from them only by the thin, non-magnetic wall of the cylinder at the ends of the cavities.
The magnets 66 disposed in the key adjacent to the cylinder cavities 40 and 42 have such polarities relative to the magnetic pins 46 disposed in these cavities as to attract the pins 46 against the bias of the springs 48. As illustrated in FIG. 4, the pin 46 moves into the cavity 40 so that its end no longer projects into the cavity 32 to prevent rotation between the cylinder 14 and the housing 12. The pin contained within the cavity 42 (not shown) moves in the same manner against its biasing springs.
The magnets 66 supported adjacent to the cavities 38 and 44 have such magnetic polarity relative to the magnets 50 disposed in these cavities as to repel the magnets 50. This causes the magnetic pin 50 to tend to move out of its cavity 44, compressing the spring 36. This motion causes the pin 52 to withdraw within the cavity 36 as illustrated in FIG. 4 so that the pin no longer straddles the space between the shoulders 20 and 24 and allows rotation of the cylinder relative to the housing. A similar action occurs with respect to the pin contained within the cavity 44. Accordingly, the cylinder 14 may then be rotated relative to the housing 12 by a rotation of the key 60 which transfers its torque through the stud 72. This causes a rotation on the rod 22 forming part of the cylinder 14 to what will be termed an "opened" position.
The rod 22 is coupled through a conventional lock mechanism to a bolt 70 forming part of the door which is withdrawn when the cylinder is in its opened position and is extended to engage a suitable mating recess when the cylinder is in its locked position.
The lock housing 12 is mounted within its door 10 so that its forward face is flush with the door, leaving a cylindrical recess forward of the surface 26 of the lock cylinder for insertion of the key 60. When the key is not in abutment to the lock, pins 52 and 46 bridge the gap between the cylinder and the housing to prevent rotation of the cylinder and opening of the lock. When the key is brought into position as illustrated in FIGS. 4 and 6 the pins move against their springs to allow rotation of the cylinder.
The number, position and polarity of the recesses and pins within the cylinder and housing may be varied in different locks so as to increase the difficulty of picking the lock.
In other embodiments of the invention the end of the cylinder 14 need not be exposed in order to allow means for exerting a rotational force on the cylinder. Rather, other mechanisms, such as a door handle, could be provided for swinging the bolt 70. Also, the ends of the key magnets need not be exposed at the end of the key, but might be covered by a thin layer of the key material to make it difficult to reproduce the key.