Patent Application
20050199026
1. Field of the Invention
The present invention relates to door locks, and in particular to electric door locks that can be operated in both the fail-safe and fail-secure mode and comprises improvements to increase the operating life of the lock.
2. Description of the Related Art
Security doors to prevent theft or vandalism have evolved over the years from simple doors with heavy duty locks to more sophisticated egress and access control devices. Hardware and systems for limiting and controlling egress and access through doors are generally utilized for theft-prevention or to establish a secured area into which (or from which) entry is limited. For example, stores use such secured doors in certain departments (such as, for example, the automotive department) which may not always be manned to prevent thieves from escaping through the door with valuable merchandise. In addition, industrial companies also use such secured exit doors to prevent pilferage of valuable equipment and merchandise.
One type of door lock which has been used in the past to control egress and access through a door is an electromagnetic system which utilizes an electromagnet mounted on a door jamb, with an armature mounted on the door held by the electromagnet to retain the door in the closed position when the electromagnet is actuated. Such locking mechanisms are illustrated in U.S. Pat. No. 4,439,808, to Gillham, U.S. Pat. No. 4,609,910, to Geringer et al., U.S. Pat. No. 4,652,028, to Logan et al., U.S. Pat. No. 4,720,128 to Logan, Jr., et al., and U.S. Pat. No. 5,000,497, to Geringer et al. All of these references utilize an electromagnet mounted in or on a door jamb and an armature on the door held by the electromagnet to retain the door in the closed position. Such electromagnetic locking systems are quite effective at controlling egress and access through the door they are installed on. Unfortunately, however, such systems are quite expensive, and require a fairly complex installation, often with the electromagnet being mounted in the door jamb.
Another type of system which is known in the art is the electric door strike release mechanism, in which a latch bolt located in and extending from a locking mechanism located in a door is receivable in an electrically operable door strike mounted in the frame of the door. The door may be opened either by retracting the latch bolt into the locking mechanism to thereby disengage it from the door strike, or by electrically actuating the door strike mechanism to cause it to open and to thereby release the extended latch bolt from the door strike mechanism. Typically, such electrically operable door strikes pivot to allow the door to close without the door strike mechanism being electrically actuated. Such door strike mechanisms are illustrated in U.S. Pat. No. 4,017,107, to Hanchett, U.S. Pat. No. 4,626,010, to Hanchett et al., and in U.S. Pat. No. 5,484,180, to Helmar. Like the electromagnet/armature systems discussed above, electrically operated door strike systems are also expensive, and require a significant installation into the door jamb, which must usually be reinforced.
Electrically operable door locks have also been developed that can be installed on a door through which access is to be controlled by an electrically operable security system. Such a lock is disclosed in U.S. Pat. No. 5,876,073 to Geringer et al. The door opening mechanism of the door lock is selectively locked and unlocked by controlling the supply of electricity to the door lock to thereby control access or egress through the door. The electrically operable door lock uses an electromagnetic actuator to drive a locking member between a locked position in which it engages a latch actuating member to prevent it from being rotated to retract a latch bolt to open a door, and an unlocked position in which it is disengaged from the latch actuating member to allow it to be rotated to retract the latch bolt to open the door. By reversing the position of the electromagnetic actuator in the door lock apparatus, the system may operate in either a fail secure mode in which the electromagnetic actuator must be powered to unlock the door, or a fail safe mode in which the electromagnetic actuator must be powered to lock the door.
A universal solenoid actuator has been developed for use in either a fail-safe or a fail-secure lock mechanism or a push-type or pull-type mechanism and comprises a reversible coil assembly. Such an actuator is disclosed in U.S. Pat. No. 5,933,067 to Frolov. It includes at least one plunger and a module for receiving electricity from a power supply and delivering the electricity to the coil assembly. The coil assembly includes a housing which defines a bore extending through the coil assembly, at least one coil surrounding the bore and first and second fittings at opposed ends of the bore. The plunger is received within the bore and is actuated upon application of an electrical potential to the coil assembly. When used with a fail-safe lock, the first fitting is affixed to the lock. When used with a fail-secure lock, the coil assembly is reversed to affix the second fitting to the lock. The coil assembly is terminated at opposite ends for first and second threaded fittings that are sized and shaped to be affixed to conventional lock mechanisms by merely threading the coil assembly into the locking mechanism. Whichever of the first and second fittings is not affixed to a lock mechanism can receive a threaded connector to deliver electricity to the coil assembly.
A door lock has also been developed in which an outside knob assembled at the outside of a door can be manually controlled to be operationally associated with or dissociated from the door lock. Such a lock is described in U.S. Pat. No. 6,581,423 to Lin. When the door lock is fastened, the outside knob can be selectively decoupled from the door lock and become idle. The lock utilizes a manually-operatable controller that is shaped as a seesaw button that protrudes partially from the lock's front plate. By manually operating the button the outside knob is selectively decoupled. This helps prevent the door lock from being damaged and a force is exerted on the doorknob by external impact or by forcible turning.
One embodiment of an electric door lock according to the present invention is interchangeable between fail safe and fail secure modes and comprises a housing for receiving the internal components of the door lock. A latch bolt is mounted within the housing and is movable between partially extended from and retracted into the housing. A doorknob, lever, handle, or other means for turning the components of a lock (hereinafter referred to as a “doorknob”), is mounted to the housing and is rotatable to retract the latch bolt. A solenoid assembly is also mounted within the housing and can be interchangeably arranged to cause the lock to operate in a fail secure mode wherein the doorknob is prevented from retracting the latch bolt when the solenoid is not energized, or a fail safe mode wherein the doorknob is allowed to retract the latch bolt when the solenoid is not energized. The solenoid is nested in place within the housing in both modes.
Another embodiment of an electric door lock according to the present invention is interchangeable between fail safe and fail secure modes, and also comprises similar housing, latch bolt, and doorknob. A solenoid assembly is mounted within the housing and comprises a solenoid body, plunger and rod/tip assembly. The plunger is movably mounted within and drawn into the solenoid body when the solenoid assembly is energized. The rod/tip assembly is capable of being mounted to either end of the plunger to interchange the solenoid assembly to cause the lock to operate in a fail safe or fail secure mode.
Still another embodiment of an electric door lock according to the present invention is interchangeable between fail safe and fail secure modes, and also comprises a similar housing, latch bolt and doorknob. A solenoid assembly is mounted within the housing. A hub mechanism is also mounted within the housing with the doorknob mounted thereto. A coupling member is held within the housing and movable between a first coupling position to allow the hub mechanism to rotate when the doorknob is rotated, or a second coupling position wherein the hub mechanism is not allowed to rotate when the doorknob is rotated. The hub mechanism retracts the latch bolt when the hub mechanism is rotated. A locking lever is also mounted within said housing and operably arranged between the solenoid assembly and the coupling mechanism. The locking lever is movable by the solenoid assembly between first and second locking lever positions, which cause the coupling mechanism to move between the first and second coupling positions.
One embodiment of a solenoid assembly according to the present invention comprises a solenoid body having a longitudinal bore and a coil surrounding the longitudinal bore. Electrical conductors are included to apply an electrical signal to the coil. A plunger is movably arranged within the longitudinal bore and drawn into the solenoid housing when the coil is energized. A rod/tip assembly is mounted to the plunger and a conical spring is mounted between the rod/tip assembly and the solenoid body. The conical spring is compressed when the plunger is drawn into the solenoid body, the conical spring urging the rod/tip assembly to extend from the solenoid body when the coil is not energized.
These and other features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings, in which:
The inventions herein are described with reference to a particular lock but it should be understood that the inventions can be similarly used in other types of locks and other devices unrelated to locks. The components described herein can have many different shapes and sizes beyond those shown and can be arranged in many different ways beyond those described herein.
The lock 10 generally comprises a housing 12 that can be many different shapes and sizes, but has a height, width and depth so that it can be mounted within a door and hold the internal lock components described below. The housing 12 comprises a back plate 13 and is shown in
A latch bolt 16 is mounted within the housing 12 and can be driven by a doorknob (shown in
A hub mechanism 22 is mounted within the housing 12, below the latch bolt 16, and has a handle aperture 24 to receive a spindle 44, 46 as shown in
An auxiliary latch 20 is mounted within the housing 12 parallel to the latch bolt 16, and comprises a front portion that extends from a safety bolt opening 32 in the front plate 14. The auxiliary latch 18 is urged by safety bolt spring 34 to the extended position, and the auxiliary latch 18 can be moved to a retracted position within the housing 10, against the force of string 34, by a force applied to the end of auxiliary latch 18. The operation of auxiliary latch 18 and spring 34 cooperate to hold the latch bolt 14 at a predetermined position. In one embodiment according to the present invention, the auxiliary latch 18 is arranged such that when in its retracted position, the latch bolt 16 can only be retracted by the inside doorknob and the key cylinder. When the auxiliary latch 20 is in its extended position the latch bolt 16 can be retracted. In operation, when the door is closed, the auxiliary latch 20 can be compressed by the frame of the door or the strike plate, and holds the latch bolt 16 at its extended position such that the latch bolt 16 is blocked against operation driven by the outside doorknob.
The hub mechanism 22 comprises a coupling member 36 that can be moved between an extended position as shown in
Referring again to
According to the present invention, the lock 10 also comprises a solenoid 60, a locking lever 62, and a rocker arm 64 that cooperate with coupling member 36 to allow one or both of the doorknobs 40, 42 to retract the latch bolt. Many different solenoids can be used in lock 10 including single or multiple stage coils that are operable with different voltages, such as 12 or 24 volts.
Locking lever 62 is mounted to the housing 12 by locking lever pin 66, with the solenoid 60 mounted at one end of the lever 62 and the rocker arm 64 mounted at the other end. The solenoid 60 includes a rod/tip assembly 68 that is mounted to the solenoid's internal plunger. As described below in
The lever's rocker arm end 72 has a slider surface 74 that cooperates with the rocker arm 72 to extend or retract the coupling member 36. As the rocker arm end 72 moves toward the back of the housing 12, opposite the front plate 14, the end of the rocker arm 64 in contact with the slider surface 74 slides up the surface 74. This causes the rocker arm 64 to rotate about the rocker arm pin 76 and push the coupling member 36 to its retracted position wherein the door handles cannot turn the hub mechanism. When the rocker arm end 72 moves toward the flange plate 14, the rocker arm 64 rotates the opposite direction around rocker arm pin 76, allowing the coupling member 36 to move to its extended position, wherein the doorknobs can turn the hub mechanism 22. The rocker arm 64 is held in contact with the slider surface 74, by rocker arm spring 78 that runs between the rocker arm 64 and the lever's rocker arm end 72.
The rod/tip assembly 106 has a lower threaded section 118 on one end and a hemispheric tip 120 at the other. The plunger 104 also has a longitudinal bore 122 that has a bore threaded section 124 at the plunger's tapered end 114. As more fully described below, the lower threaded section 120 mates with the bore threaded section 122 when the rod/tip assembly 106 is mounted to the plunger 104.
As shown in
According to the present invention, the solenoid assembly is not fixed in the housing 12 shown in
In another embodiment according to the present invention, a solenoid cradle 132 is provided that can be provided to hold the solenoid body 102. The cradle 132 is at least partially hollow and shaped to accept the solenoid body 102 and comprises a bottom surface and four walls. The solenoid body 102 rests within the cradle with the walls preventing sideways or front and back movement of the solenoid body 102. The solenoid body 102 is held in the cradle 132 between the back plate and cover plate in an opening/indentation to hold the solenoid body in the housing. The cradle 132 can be held in place in many different ways, such as the cradle 132 resting in a opening/indentation in one of the housing walls. In another embodiment according to the present invention, the cradle rests in the back plate 13 of the housing 12 by mounting posts 134 that are inserted into mounting holes 135 the back plate 13. When the lock is assembled and the housing cover plate is in place, the cover plate blocks the solenoid body 102 from moving out of the cradle 132. The solenoid body is held in place between the cradle bottom surface and the housing cover plate, and the cradle walls. By utilizing this cradle arrangement, the solenoid assembly 100 can be easily removed to have its mode changed, and then placed back in the cradle. This arrangement avoids the time and inconvenience of having to remove and replace a solenoid that is fixed to the lock housing by screws, bolts, welds, etc.
A spring 136 is mounted on the plunger 104 between the solenoid body 102 and the hemispheric tip 120, to urge the plunger to extend from the solenoid body 102. Many different springs can be used having many different longitudinal and cross-section shapes, such as conventional helical springs, with a preferred spring having a conical longitudinal shape that provides advantages over conventional springs as described below in
Referring to
Referring to
In
One of the advantages of the present invention is that lock 10 can be quickly and easily changed to operate in either the fail safe or fail secure modes. If the lock 10 were arranged in the fail safe mode as shown in
To change back to fail safe mode, the front plate is removed and the solenoid assembly 100 is lifted out of the cradle 132. The rod/tip assembly 106 is turned out of the plunger 104 and the conical spring 36 is stored. The solenoid housing is turned 180 degrees and the rod and tip assembly 106 is inserted into the first solenoid opening 128. The rod/tip assembly 106 is then turned onto the plunger's tapered end 114 and the solenoid assembly 100 is returned to the cradle 132. The cover plate is then secured on the housing 12.
Referring now to
The spring 136 can be arranged to provides advantages over the conventional springs and can improve both the performance and life of the lock 10. The preferred spring has a spring rate (ratio of load over distance of compression) that closely matches the power curve of the solenoid. The preferred spring can also be compressed without stacking of the turns of the spring, which helps prevent locking of the spring turns over other spring turns and allows the spring to compress to a very small height. The can be accomplished by springs having many different shapes.
The conical spring provides additional advantages related to the life of the solenoid assembly 100. When a helical spring is used to oppose plunger movement, the solenoid should be strong enough at the beginning of its stroke or power curve (the point where it is the least efficient) to compress the spring. The conical spring can be arranged to more closely match/track the power curve of the solenoid such that when a conical spring is used, a lower current solenoid can be used. Lower current allows the solenoid to operate at a cooler temperature and can extend the operational life of the solenoid.
The conical shape of spring 136 also allows the spring to compress to a very small height. As the spring is compressed, each turn of the spring 136 is pushed into the spring below, instead of stacking on the turn below as occurs in helical springs. A fully compressed conical spring can compress to a height as small as approximately one turn of the spring.
The lock 10 also comprises an improved latch bolt arrangement that can prevent latch bolt damage compared to prior latch bolts. Prior latch bolts utilize a holding plate as a retractor to align the latch bolt. When excessive torque is applied to the hub mechanism in the reverse of its intended operational direction damaging the internal components of the lock and causing the lock to fail.
The retractor 160 can also be made of a material that melts at a certain temperature such that the lock 10 does not function and door cannot be opened after the temperature exceeds the temperature. One embodiment of a retractor 160 according to the present invention can be made of glass filled nylon that melts at a temperature of approximately 450 degrees. Glass filled nylon provides the additional advantage of being resilient and self lubricating to allow the latch finger to slide across it efficiently.
Although the present invention has been described in considerable detail with references to certain preferred configurations thereof, other versions are possible. The invention can be used in different locks and different components can be used in the locks described above. The steps taken above to interchange the lock between fail safe and fail secure modes can be taken in different order and different steps can be used. Therefore the spirit and scope of the claims should not be limited to the preferred version contained herein.
