Electric latch retraction bar

Abstract

An electric latch retraction device comprising a housing for receiving a plurality of internal components of the electric latch retraction device. An actuator mechanism is included in the housing, the actuator mechanism is adapted to impart linear movement on a latch, such that the latch is retracted towards the housing. A holding mechanism is also included in the housing, the holding mechanism holds the latch in a fully retracted position.

Claims

1. An electric latch retraction device comprising: a housing containing an electric motor wherein said electric motor is adapted to impart linear movement on a latch, such that said latch is retracted towards said housing and toward a fully retracted position; a holding mechanism mounted in said housing, wherein said electric motor comprises an armature adapted to extend from said electric motor and engage said holding mechanism when said latch is in said fully retracted position, said holding mechanism adapted to hold said latch in said fully retracted position with a holding strength sufficient to hold said latch in said fully retracted position with said electric motor in an off state and wherein said latch is released from said fully retracted position when said holding mechanism is in an off state and said electric motor is in said off state; and a sensor, said sensor configured to engage said armature and sense the position of said armature.

2. The electric latch retraction device of claim 1, wherein said sensor is configured to signal a controller to place said motor in said off state when said sensor engages said armature during retraction of said latch.

3. The electric latch retraction device of claim 2, wherein said armature extends from said electric motor as said latch is retracted towards said housing.

4. The electric latch retraction device of claim 2, wherein said armature is magnetically conductive.

5. The electric latch retraction device of claim 1, wherein said holding mechanism is magnetically conductive.

6. The electric latch retraction device of claim 1, wherein said holding mechanism is an electrically actuated magnetic coil.

7. The electric latch retraction device of claim 1, said electric motor comprising an internal mechanism adapted to receive an internal linkage.

8. The electric latch retraction device of claim 7, wherein said internal linkage couples said latch to said electric motor, said internal linkage is adapted to mate with said internal mechanism.

9. The electric latch retraction device of claim 8, said internal linkage comprising a threaded section to mate with said internal mechanism to impart linear movement on said latch.

10. The electric latch retraction device of claim 8, wherein said internal mechanism is a nut, said internal linkage mating with said nut to impart linear movement on said latch.

11. The electric latch retraction device of claim 1, wherein said electric motor is a rotary motor.

12. The electric latch retraction device of claim 1, wherein said electric motor is a step motor.

13. An electric latch retraction device comprising: a housing containing a plurality of internal components of said electric latch retraction device, said internal components comprising an actuator mechanism adapted to impart linear movement on a latch; said internal components further comprising a magnet mounted in said housing, said magnet adapted to hold said latch in a fully retracted position, wherein said internal components further comprise an armature adapted to extend from said actuator mechanism and engage said magnet when said latch is in said fully retracted position; a bias spring in said housing, said bias spring adapted to position said latch in a latched position, wherein said latch is released from said fully retracted position when both said actuator mechanism and said magnet are in an off state; and a sensor, said sensor configured to engage said armature and sense the position of said armature.

14. The electric latch retraction device of claim 13, wherein said internal components further comprise an internal linkage, said internal linkage coupling said latch to said actuator mechanism.

15. The electric latch retraction device of claim 14, wherein said bias spring is included on said internal linkage, said bias spring located on an actuator mechanism end of said internal linkage.

16. The electric latch retraction device of claim 13, wherein said bias spring reverses the linear motion caused by said actuator mechanism when said latch is released from said retracted position.

17. The electric latch retraction device of claim 13, wherein said bias spring reverses the linear motion caused by said actuator mechanism when said magnet is in said off state.

18. An electric latch retraction device comprising: a housing containing an electric motor, wherein said electric motor is adapted to impart linear movement on a latch, such that said latch is retracted towards said housing and towards a fully retracted position; and a magnetically conductive holding mechanism mounted in said housing, wherein said electric motor comprises an armature adapted to extend from said electric motor and engage said magnetically conductive holding mechanism when said latch is in said fully retracted position, said magnetically conductive holding mechanism adapted to hold said latch in said fully retracted position with a holding strength sufficient to hold said latch in said fully retracted position with said electric motor in an off state, wherein said latch is released from said fully retracted position when said magnetically conductive holding mechanism is in an off state and said electric motor is in said off state; and a sensor, said sensor configured to engage said armature and sense the position of said armature.

19. The electric latch retraction device of claim 13, wherein said sensor is configured to signal a controller to place said actuator mechanism in said off state when said sensor engages said armature during retraction of said latch.

20. The electric latch retraction device of claim 18, wherein said sensor is configured to signal a controller to place said electric motor in said off state when said sensor engages said armature during retraction of said latch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is perspective view of a door utilizing one embodiment of an electric latch retraction push bar exit device according to the present invention;

(2) FIG. 2 is a perspective view of one embodiment of an electric latch retraction push bar exit device according to the present invention;

(3) FIG. 3 is an exploded view of a motor and holding magnet assembly that can be utilized in one embodiment of an electric latch retraction push bar exit device according to the present invention;

(4) FIG. 4 is a plan view of the latch retraction push bar exit device shown in FIG. 2 in the unlatched condition; and

(5) FIG. 5 is a plan view of the latch retraction push bar exit device shown in FIG. 2 in the latched condition.

DETAILED DESCRIPTION OF THE INVENTION

(6) The present invention provides an electric latch retraction push-bar exit device (“push-bar exit device”). SDC where the latch can be retracted through the standard pushing action on the push-bar. The exit devices according to the present invention can comprise secondary mechanisms for retracting the latch, such as through an electric motor. On some embodiments, the motor can be internal to the device housing and can comprise a stepper motor type linear actuator to retract the latch. When the actuator has moved to the retracted (unlatched) position, a holding magnet can be activated to hold the actuator in the unlatched position to allowing the motor to be switched off. Many different holding magnets can be used such as a magnetic holding coil.

(7) Upon loss of power or when controller electronics remove power from the magnetic holding coil the actuator can be returned to the at-rest or latched position. In some embodiments biasing springs can be used to return the latch to the locked position and in one embodiment a combination of an actuator biasing spring and a latch biasing spring can reverse the linear movement of the actuator and cause the device to return to the latched position.

(8) It is understood that when an element or component is referred to as being “on”, “connected to” or “coupled to” another element, it can be directly on, connected to or coupled to the other element or intervening elements may also be present. Furthermore, relative terms such as “front”, “back”, “inner”, “outer”, “upper”, “above”, “lower”, “beneath”, and “below”, and similar terms, may be used herein to describe a relationship of one component of element to another. It is understood, however, that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

(9) Although the terms first, second, etc. may be used herein to describe various elements or components these elements and components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first element or component discussed below could be termed a second element or component without departing from the teachings of the present invention.

(10) Embodiments of the invention are described herein with reference to certain illustrations that are schematic illustrations of idealized embodiments of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances are expected. Embodiments of the invention should not be construed as limited to the particular shapes of the elements or components illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of an element or component and are not intended to limit the scope of the invention.

(11) FIG. 1 shows one embodiment of a door 10 utilizing a push-bar exit device 12 according to the present invention. The push-bar exit device 12 is mounted in convention manner to the door 12 with a horizontal orientation and location that allow for the exit device's latch to engage a latch opening in the door frame 13. When engaged the door 10 is prevented from opening, when the latch is retracted from latch opening the door 10 can open. As with convention devices, depressing the push-bar 14 causes the latch to retract from the latch opening to allow opening of the door 10.

(12) Referring now to FIGS. 2-5, the push-bar exit device comprises a housing 18 with the push-bar 14 movably mounted to the housing so that it can be depressed. As with most conventional push-bar exit devices, this action can retract the latch so that it is partially within the housing. As the push-bar 14 is depressed it causes a latch 20 to retract toward the housing. As discussed above, when the latch 20 is retracted the door utilizing the push-bar exit device 12 can be opened. Many different known mechanisms can be used to cause the latch 20 to retract as the push-bar 14 is depressed, and it is understood that each of these known mechanisms can be utilized in different embodiments of push-bar exit devices according to the present invention.

(13) As mentioned above, push bar exit devices according to the present invention are arranged so that latch 20 can be retracted in a manner beyond the manual pushing of the push-bar 14. These can include many different types of linear actuators. In one embodiment, the latch 20 can be retracted in response to an electrical signal, and many different devices and mechanisms can be used to retract the latch 20 is response to an electrical signal. In one embodiment, an electric motor 22 can be used to retract the latch, with motor 22 mounted in place within the housing 18. An adjustment plate 24 can be included within the housing 18 with the motor 22 mounted to the adjustment plate 24 by a mounting block 26. As mentioned above, many different types of motors can be used with a suitable motor 22 such as a rotary or step motor.

(14) The motor 22 can impart linear movement on the latch 20 using many different mechanisms. In one embodiment, the motor 22 can comprise an internal nut that turns when an electrical signal is applied to the motor 22. The housing 18 can also have internal linkage 28 that connects at one end to the latch 20 and at the other end to the motor 22. The motor end of the linkage 28 has a threaded section that mates with the motor's internal nut, and as the nut turns on the threaded section linear movement is imparted on the latch 20 through the linkage 28.

(15) The motor further comprises an armature 32 that extends from the motor 22 as the latch 20 is retracted. A holding magnet 34 is mounted to the adjustment plate 24 by a magnet mounting block 36, with the magnet 34 in alignment with the armature 32. Many different magnets can be used, with a suitable one being an electrically actuated magnetic coil. An actuator switch/sensor 38 is mounted integral to the magnet 34 and as mentioned above, in the path of travel of the armature 32 to sense its position relative to the magnet 34.

(16) A controller 40 can be utilized to control operation of the push-bar exit device 12, and in different embodiments the controller 40 can be remote or local to the exit device 12. The controller can communicate with the exit device using many different “hard-wire” and wireless communication links. In the embodiment shown, the controller comprises commercially available electronics interconnected in conventional way, and in different embodiments the controller 40 can perform many different functions. In the embodiment shown, when the armature 32 engages the sensor 38, the sensor 38 signals the controller 40 to turn the motor off to allow the actuator mechanism to “coast” to the fully retracted position. This coasting action is designed to compensate for manufacturing tolerances in the internal components of the exit device, including but not limited to the adjustment plate 24 and linkage 28. This allows for a “self adjusting” feature eliminating the need to readjust the device linkage as the exit device 12 wears from use.

(17) The controller 40 is also designed to deliver a “timed” period of motor activation. This “timed” period is set to be slightly longer than is needed to retract the latch 20. The controller 40 monitors the actuator sensor 38 to determine when to remove motor power to enable the “coasting” effect and ensure a positive mating of the armature 32 against the magnet 36.

(18) Should the sensor 38 not indicate that the latch 20 has not been retracted and “timed” motor active period has expired, the power to the motor 22 can be turned off. A rest period for motor cooling is initiated and the latch retraction cycle can be attempted again. The motor 22 will not be damaged in the event of binding of the panic device due to door alignment problems or door preload.

(19) As mentioned above, when the armature 32 moves to the retracted position and engages the sensor 38, the armature contacts the magnet. The magnet holds the armature 32 in the retracted position, allows the motor to be switched off while still keeping the device in the unlatched condition. This allows for keeping the exit device 12 in the unlatched condition while not consuming power by continued activation of the motor. The power needed to energize the magnet 34 is less than that consumed by the motor 22, with this arrangement realizing significant reduction in power consumption compared to similar devices without a magnet 34.

(20) A biasing spring 42 is included on the linkage 28 biasing the linkage 28 to the latch 20 to the latched condition. If power is removed from the magnet 34, either by the controller or by loss of power to the exit device 12, the bias spring reverses the linear motion of the motor and causes the exit device 12 to return to the latched condition.

(21) Although the present invention has been described in detail with reference to certain configurations thereof, other versions are possible. Therefore, the spirit and scope of the invention should not be limited to the versions described above.