# Patent

## Title
Electronic door lock assembly preload compensation system

## Abstract

Disclosed are various embodiments of lock devices, systems, and methods. A locking system includes a locking mechanism with a controller configured to provide an actuation signal to an electronic actuator to extend or retract a locking mechanism and to adjust an allowable peak current for operating the electronic actuator to throw the deadbolt based on whether the allowable peak current is sufficient for the locking mechanism to achieve its locked or unlocked positions. The allowable peak current can be adjusted over time between a minimum and maximum peak current, thus optimizing the actual current draw from the electronic actuator required to throw the locking mechanism and minimizing power consumption.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims the benefit of the filing date of U.S. Provisional Application No. 61/671,511 filed on Jul. 13, 2012, which is incorporated herein by reference.


BACKGROUND
Electromechanical door locks often utilize a battery-based power supply. An issue with many current deadbolt locks that throw the bolt using battery-powered actuators is that they tend to either lack enough power to drive the bolt against door mismatch during strike, or they draw too much battery power and thus create a short battery life. Security, cost, and convenience considerations dictate minimizing current drain and power consumption in order to increase battery life and reduce the uncertainty, expense and inconvenience imposed by dead battery events. Therefore, further improvements in this area of technology are needed.
SUMMARY
The present application relates to systems, apparatus, and methods that minimize power consumption of door locking systems, thus increasing battery life. The systems, apparatus and methods can also enhance the ability of the electronic actuator to extend and retract the locking mechanism in the event of significant bolt-strike mismatch that can be caused by, for example, weather stripping or warped doors. The systems, apparatus and methods can compensate for higher preloads that may occur over time by increasing the allowable peak current that the electronic actuator can draw from the power source to throw the locking mechanism, thus minimizing power consumption initially but providing for the ability to increase the overall force that drives the locking mechanism over time as may be needed due to bolt-strike mismatch conditions that arise. The systems, apparatus and methods disclosed herein can also be applicable to any application in which electronic actuator power modification is desired to meet performance requirements over time and to periodically assess the power consumption needs to increase for improved performance or to decrease to save energy.
These and other aspects, embodiments, forms, objects, and characteristics of the systems and methods disclosed herein are discussed further below.



BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a schematic of a door and an electronic locking system.
FIG. 2 is a graph of the current supplied to a motor over time during travel of a locking mechanism of the electronic locking system of FIG. 1.
FIG. 3 is a flow diagram of a procedure for determining and adjusting an allowable peak current draw of an electronic actuator of the locking system of FIG. 1 during actuation of the locking mechanism.



DETAILED DESCRIPTION
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.
With reference to FIG. 1, there is shown a portion of a door 40 having a door lock assembly 50 useful to secure the door 40 to a door jamb 42 or other suitable fixed structure. The door 40 can be any variety of doors used in residential, business, etc. applications that can be used to close off passageways, rooms, access areas, and the like. The door lock assembly 50 shown in the illustrated embodiments includes a lock housing 51 and a door locking mechanism such as a bolt 52. Bolt 52 is shown in the locked position in FIG. 1 as indicated by bolt end 54 and in the unlocked position as indicated by bolt end 54′. Bolt 52 can move in to and out of the door jamb 42 when securing the door 40. The bolt 52 can move from a retracted position, as indicated by bolt end 54′, to an extended position, as indicated by bolt end 54. Due to mismatch between bolt 52 and jamb 42 and/or strike 44, bolt 52 can be located at a failed position which is at any position between the extended position of end 54 and the retracted position of end 54′ shown in FIG. 1.
The bolt 52 can be moved based upon a force imparted through any one or a combination of an electronic actuator 56 internal to the door lock assembly 50, a key (not shown), and a user device such as a thumbturn (not shown.) Door lock assembly 50 can include a key cylinder (not shown) having a keyhole 58 used to receive a key which can be used to manipulate the bolt 52 to secure the door 50. The front side door lock assembly 50 can alternatively and/or additionally include a numeric pad (not shown) that can be used to engage electronic actuator 56 to drive the bolt 52 if provided an appropriate pass code. Door lock assembly 50 can also include a power module 60 connected to electronic actuator 56 to supply power for turning bolt 52. The power module 60 includes provisions to retain a supply of power, such as but not limited to batteries. In one embodiment the power module 60 is a holder that includes provisions to receive any number and types of batteries, such as but not limited to size AA batteries.
The electronic actuator 56 can receive power via a cable or other suitable connection with the power module 60. In one embodiment the electronic actuator 56 includes a motor that is a permanent magnet direct current (PMDC) motor, but the motor can take a wide variety of other forms useful to convert power provided by the power module 60 to mechanical output that can be used to actuate the bolt 52. Various arrangements for connecting the motor to bolt 52 are contemplated, examples of which are provided by U.S. patent application Ser. No. 13/754,661 filed on Jan. 30, 2013. Furthermore, U.S. patent application Ser. No. 13/754,661 is incorporated herein by reference for any and all purposes.
Electronic actuator 56 is also connected to a controller 62 having a memory 64 for storing instructions for operation of electronic actuator 56. Controller 60 is operable to provide control signals to electronic actuator 56 to throw bolt 52 in response a command signal, such as a locking command or an unlocking command. Controller 60 is further operable to limit the allowable peak current to electronic actuator 56 from power module 60 to operate the motor that actuates bolt 52. In addition, controller 62 is configured to adjust the allowable peak current from power module 60 to electronic actuator 56 in response to one or more determinations that bolt 52 is in a failed position after actuation via electronic actuator 56 at the previously allowed peak current.
As shown in FIG. 2, a graph of the current from power module 60 over time for actuating or throwing bolt 52 is provided. At time t0 the current required to initiate movement of bolt 52 is provided. During the time between t0 and t1, the current supplied to the motor of electronic actuator 56 during travel of bolt 52 to its extended or retracted is shown. At the end of the bolt travel at time t1, the current increases rapidly to a peak current Ip. By limiting the peak current Ip during actuation of bolt 52, battery life can be preserved. Therefore, the controller 62 is programmed so that upon installation and initialization of the door lock assembly 50, the allowable peak current is set at a minimum that, for example, corresponds to no preload acting on bolt 52 as it moves between its extended and retracted positions. If the door and door lock assembly are maintained in a condition in which no preload is exerted on bolt 52, then door lock assembly 50 will continue to operate at the initial allowable peak current. However, the allowable peak current can be increased by controller 62 in response to a failure event determination in which the bolt 52 does not achieve its extended or retracted position after actuation with electronic actuator 56 at the previous allowable peak current. It is further contemplated that the allowable peak current for operation of electronic actuator 56 can vary between a minimum peak current which corresponds the current required to extends and retract bolt 52 under no preload to a maximum peak current which, for example, can be established based on protecting components of door lock assembly 50 from damage.
FIG. 3 provides one embodiment of a procedure that can be programmed into memory 64 and executed by controller 62. Procedure 100 begins at operation 102 in which the allowable peak current is initially programmed into or determined by controller 62. As discussed above, the allowable peak current can be the peak current in which bolt 52 can be actuated with no preload, although other initial allowable peak currents are not precluded. For example, in some embodiments the allowable peak current can be learned upon installation of door lock assembly 50 to account for actual installation conditions.
Procedure 100 continues at operation 104 in which a command signal is received by controller 62 to actuate and lock or unlock bolt 52. Any suitable means for initiating a command signal is contemplated, such as by keypad entry, key fob entry, preprogrammed instructions or timers, wired and wireless instructions, and/or system wide communications. After actuation of bolt 52, procedure 100 continues at operation 106 in which an actual position of bolt 52 is determined relative to a desired position contemplated by the electronic command. If bolt 52 achieves the extended or retracted position of the corresponding locking or unlocking command, then no failure event is indicated at conditional 108. However, if the desired position is not achieved, then a failure event can be flagged at conditional 108.
After flagging of a failure event at condition 108, conditional 110 includes a determination whether the allowable peak current for operation of electronic actuator 56 should be adjusted. In certain embodiments, a predetermined number of consecutive failure events are required to adjust the allowable peak current, preventing inadvertent adjustments due to temporary conditions associated with the door and/or door lock assembly 50. If conditional 110 is affirmative, procedure 100 continues at operation 112 in which the allowable peak current for operation of electronic actuator 56 is adjusted. After completion of operation 112, or if conditionals 108, 110 are negative, procedure 100 continues at operation 104 to await another electronic command.
Systems, apparatus and methods are disclosed that minimize power consumption of door lock assemblies such as autothrow deadbolt systems to save battery life, while providing the ability of the actuator to throw the deadbolt in the event of significant bolt-strike mismatch that can be caused by, for example, weather stripping or warped doors. In one form this may be accomplished through a motor current sensing algorithm that “learns” a door's preload that is required for the actuator to throw and retract the deadbolt locking mechanism upon initial installation. The systems, apparatus and methods will compensate for higher preloads that may occur over time by increasing the peak current that the motor of the actuator can draw from the battery to throw the deadbolt, thus minimizing power consumption initially but providing for the ability to increase the overall force that drives the deadbolt over time that may occur due to bolt-strike mismatch conditions that may arise. The systems and methods disclosed herein can also be applicable to any application in which actuator power modification is desired to meet performance requirements over time and to periodically assess the power consumption needs to increase or can be decreased to save energy.
A motor current sensing algorithm can be employed with controller 62 to “learn” a door's preload in order to help improve battery life of locking mechanisms such as autothrow deadbolts by only supplying the necessary current to extend or retract the deadbolt based on its preload. This may be accomplished with a multi-step current limit setting that will automatically adjust once the deadbolt fails to extend or retract via motor operation to the desired position after a predetermined, certain number of attempts. In one form, by default, the allowable peak current will be at the lowest setting when the door lock assembly is installed onto the door.
The deadbolt will extend and retract at the lowest allowable peak current setting indefinitely unless there are a certain number of consecutive failed extensions or retractions due to increased door preload. A failure event can be determined by, for example, the motor stopping because of an attempt to draw current in excess of the allowable peak current during the failed attempt. As a result, the controller 62 can automatically adjust the allowable peak current to the next higher allowable peak current setting. From this point on, the motor will use this new allowable peak current value before stopping actuation. This will allow the deadbolt to extend and retract into the door with more force in an effort to overcome the increased preload. This incremental adjustment in the allowable peak current can be repeated until the maximum peak current value is reached.
In one aspect, the control procedure for initially establishing a low allowable peak current and incrementally adjusting the allowable peak current in response to actual condition increases battery life over system in which a high allowable peak current is established to account for all preload conditions. By keeping the allowable peak current draw of the motor as low as possible for as long as possible, more battery capacity can be used resulting in longer battery life of the end customer.
Since the peak motor current is used to sense the end of deadbolt travel, the reaching of a simple fixed current threshold indicates that the locking mechanism has not achieved its desired position. High current peaks significantly at end of deadbolt travel. Lower peak currents have a favorable impact on battery life. Door installations with no pre-load will require far less motor torque and thus less peak motor current to confirm end of deadbolt travel. Reducing the allowable peak current threshold helps lengthen battery life, and when motor attempts to draw more than the allowable peak current an indication that preload has increased is provided.
In one form the present application includes controller that is configured to allow an initial attempt with a low allowable peak current threshold that would be sufficient to secure the deadbolt with no pre-load. If the deadbolt does not reach proper extension without attempting to exceed the low allowable peak current, the controller is configured to throw the deadbolt using a moderate peak current threshold. It would be possible to also have a three or more additional peak current thresholds until the maximum peak current threshold that provide maximum torque available is reached. One implementation could include programming the controller 62 to re-calibrate periodically in the event that the door conditions have changes and a lower peak current would now be suitable for operation of the door lock assembly.
According to one aspect, a door lock apparatus includes a locking mechanism actuatable between an unlocked position and a locked position and a power source. The door lock apparatus also includes an electronically controllable actuator operable draw an allowable peak current from the power source to actuate the locking mechanism between the unlocked position and the locked position in response to an electronic command. The door lock apparatus also includes a controller operable to control the electronically controllable actuator to actuate the locking mechanism between the unlocked position and the locked position without exceeding the allowable peak current. The controller is also configured to evaluate a preload condition on of the locking mechanism in response to the electronically controllable actuator attempting to exceed the allowable peak current in response to the electronic command. The controller is configured to increase the allowable peak current when the preload condition of the locking mechanism indicates the respective unlocked or locked positions are not achievable under the allowable peak current due to the electronic actuator attempting to exceed the allowable peak current a predetermined number of times.
In one embodiment, the controller is operable to increase the allowable peak current up to a predetermined maximum peak current. In another embodiment, the controller is operable to increase the allowable peak current in predetermined increments up to the predetermined maximum peak current. In yet another embodiment, the allowable peak current is a predetermined minimum peak current before the allowable peak current is incrementally increased. In other embodiments, the electronically controllable actuator comprises an electric motor, the locking mechanism comprises a deadbolt, and the power source is a battery.
In another aspect, a door lock apparatus includes a lock housing, a power source within the lock housing, a locking mechanism connected to the power source, and an electronically controllable actuator operable draw an allowable peak current from the power source to selectively extend the locking mechanism to a locked position in response to an electronic locking command and to retract the locking mechanism to an unlocked position in response to an electronic unlocking command. The door lock apparatus also includes a controller connected to the electronically controllable actuator that is operable to provide the commands to the electronically controllable actuator to selectively extend and retract the locking mechanism. The controller is configured to determine a position of the locking mechanism in response to one of the electronic locking command and the electronic unlocking command; identify an event failure when the position does not correspond to one of the locked position and the unlocked position in response to the respective electronic locking command and the electronic unlocking command; and change the allowable peak current in response to a predetermined number of event failures.
In one embodiment, the controller is configured so that the predetermined number of event failures includes multiple event failures that occur sequentially without an intervening determination by the controller that the actual position corresponds to the respective locked or unlocked position. In another embodiment, the controller is configured to change the allowable peak current in predetermined increments. In yet another embodiment, the controller is configured to change the allowable peak current in predetermined increments between a minimum allowable peak current that corresponds to no preload on the locking mechanism and a maximum allowable peak current.
According to another aspect, a method for operating a door lock apparatus, comprising: actuating an electronic actuator to unlock or lock the door with a door locking mechanism while supplying an allowable peak current from a power source to the electronic actuator; determining a preload condition of the door locking mechanism while actuating the electronic actuator; determining a failure event in response to the preload condition of the door locking mechanism indicating the respective locked position or unlocked position cannot be achieved without the electronic actuator exceeding the allowable peak current; and increasing the allowable peak current to the electronic door actuator in response to determining the failure event.
In one embodiment of the method, determining the failure event includes determining a predetermined number of times the preload condition prevents the desired locked position or unlocked position from being achieved before incrementally increasing the allowable peak current. In another embodiment, increasing the allowable peak current includes incrementally changing the allowable peak current between a minimum peak current and a maximum peak current. In yet another embodiment, the method includes recalibrating the allowable peak current to the minimum peak current after a period of time.
While the invention has been described in connection with what is presently considered to be a preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the present application, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow.

## Claims

1. A door lock apparatus comprising:
a locking mechanism actuatable between an unlocked position and a locked position, wherein the locking mechanism includes a power source;
an electronically controllable actuator operable to draw an allowable peak current from the power source to actuate the locking mechanism between the unlocked position and the locked position in response to an electronic command; and
a controller operable to control the electronically controllable actuator to actuate the locking mechanism between the unlocked position and the locked position without exceeding the allowable peak current and to evaluate a preload condition of the locking mechanism in response to the electronically controllable actuator attempting to exceed the allowable peak current in response to the electronic command, wherein the controller is configured to increase the allowable peak current when the preload condition of the locking mechanism indicates the respective unlocked or locked positions are not obtainable due to the electronic actuator attempting to exceed the allowable peak current a predetermined number of times.

2. The door lock apparatus according to claim 1, wherein the controller is operable to increase the allowable peak current up to a predetermined maximum peak current.

3. The door lock apparatus according to claim 2, wherein the controller is operable to increase the allowable peak current in predetermined increments up to the predetermined maximum peak current.

4. The door lock apparatus according to claim 3, wherein the allowable peak current is a predetermined minimum peak current before the allowable peak current is incrementally increased.

5. The door lock apparatus according to claim 1, wherein the electronically controllable actuator comprises an electric motor.

6. The door lock apparatus according to claim 1, wherein the locking mechanism comprises a deadbolt.

7. The door lock apparatus according to claim 1, wherein the power source is a battery.

8. A door lock apparatus comprising:
a lock housing;
a power source within the lock housing;
a locking mechanism connected to the power source;
an electronically controllable actuator operable to draw a current from the power source to selectively extend the locking mechanism to a locked position in response to an electronic locking command and to retract the locking mechanism to an unlocked position in response to an electronic unlocking command;
a controller connected to the electronically controllable actuator and operable to provide the commands to the electronically controllable actuator to selectively extend and retract the locking mechanism, wherein the controller is configured to:
limit the current drawn by the electronically controllable actuator to an allowable peak current;
determine a position of the locking mechanism in response to one of the electronic locking command and the electronic unlocking command;
identify an event failure when the position does not correspond to one of the locked position and the unlocked position in response to the respective electronic locking command and the electronic unlocking command; and
change the allowable peak current in response to a predetermined number of event failures.

9. The door lock apparatus according to claim 8, wherein the controller is configured so that the predetermined number of event failures includes multiple event failures that occur sequentially without an intervening determination by the controller that the actual position corresponds to the respective locked or unlocked position.

10. The door lock apparatus according to claim 8, wherein the controller is configured to change the allowable peak current in predetermined increments.

11. The door lock apparatus according to claim 8, wherein the controller is configured to change the allowable peak current in predetermined increments between a minimum allowable peak current that corresponds to no preload on the locking mechanism and a maximum allowable peak current.

12. The door lock apparatus according to claim 8, wherein the electronically controllable actuator comprises an electric motor.

13. The door lock apparatus according to claim 8, wherein the locking mechanism comprises a deadbolt.

14. The door lock apparatus according to claim 8, wherein the power source is a battery.

15. A door lock apparatus comprising:
a lock housing;
a power module located in the lock housing;
an electronic actuator operable to draw a current from the power module;
a locking mechanism having a locked position and an unlocked position, wherein the electronic actuator is operable to drive the locking mechanism between the locked position and the unlocked position with the current drawn from the power module; and
a controller in communication with the electronic actuator, wherein the controller is configured to limit the current drawn by the electronic actuator to an allowable peak current, to identify an event failure condition based upon at least one of the current drawn by the electronic actuator and an actual position of the locking mechanism, and to increase the allowable peak current in response to a predetermined number of event failure conditions.

16. The door lock apparatus of claim 15, wherein the controller is further configured to limit the allowable peak current to a maximum peak current.

17. The door lock apparatus of claim 15, wherein the controller is further configured to determine the actual position of the locking mechanism, to compare the actual position to a desired position of the locking mechanism, to identify a failed attempt when the actual position does not correspond to the desired position, and to identify the event failure condition based at least in part upon the failed attempt.

18. The door lock apparatus of claim 15, wherein the controller is further configured to identify a preload condition in response to an attempt by the electronic actuator to exceed the allowable peak current, and to identify the event failure condition based at least in part upon the preload condition.

19. The door lock apparatus of claim 15, wherein the controller is configured to identify the event failure condition in response to an attempt by the electronic actuator to exceed the allowable peak current during a failed attempt to move the locking mechanism to one of the locked position and the unlocked position.

20. The door lock apparatus of claim 8, wherein the electronically controllable actuator is capable of drawing a maximum peak current from the power source, and wherein the controller is further configured to initially set the allowable peak current lower than the maximum peak current.