Patent Application
20240242595
The present disclosure relates generally to multi-mode operation of fire alarm devices.
A fire alarm system can include a number of devices (e.g., alarm devices) that can detect, and/or provide a warning, when smoke, fire, and/or carbon monoxide, among other emergency situations, are present in a facility. Such warnings may be audio and/or visual warnings, for example.
A fire alarm system may be addressable. An addressable fire alarm system may utilize signaling line circuits (SLCs), which commonly may be referred to as “loops”. A loop can include a control panel and a number of fire alarm system devices including, for example, alarm devices, as well as other detectors, call points, and/or interfaces. The control panel can provide power to the devices of the loop, and bi-directional communications can take place between the control panel and the devices of the loop.
Multi-mode operation of fire alarm devices is described herein. For example, an embodiment includes an alarm device for a fire alarm system comprising a self-test component, an alarm component, and a power supply configured to operate in a first mode to provide power to the self-test component and operate in a second mode to provide power to the alarm component.
An addressable fire alarm system generally has combined power transmission and digital communications on a 2-wire loop between a control panel and a number of outstations or field devices.
The devices include fire sensors (e.g., detectors), interfaces and alarm devices. Modern systems tend to combine the alarm functions, short-circuit isolators, and input/output (I/O) functionality with the fire sensors in the same device to reduce overall system costs. A feature becoming more common with fire sensor devices is the ability to self-test. For example, testing an optical smoke sensor can include generating an aerosol stimulus at the device that is at a fire detection level and verifying that an alarm occurs responsive to that stimulus.
Fire sensing devices may include various advanced functions. For instance, in many cases, it is now not uncommon to have a voice-sounder and visual alarm device combined with the fire sensor. While adding many advanced functions into a fire sensing device may be attractive, such functions present difficulties associated with engineering within a relatively small aesthetic design and/or a reasonable product cost.
Previous approaches meet cost, size, and noise generation issues because they utilize separate switch-mode power supplies to power different functions. It is desirable therefore to control a single power supply unit (PSU) so that it can operate in different modes to power different advanced functions within the device.
Embodiments of the present disclosure include a single switch-mode power supply. The power supply can be controlled by circuitry described herein to operate in a first mode as a voltage source (e.g., during a self-test sequence) and to operate in a second mode as a current source (e.g., during an alarm condition). In some embodiments, for instance, a power supply in accordance with embodiments herein can power a self-test module of a multifunctional addressable fire alarm device in the first mode as a voltage source using negative feedback control during a self-test sequence, and can power a visual alarm component of the device (e.g., a strobe) in the second mode as a current source controlled by a digital predictive control loop to provide a low frequency filtering and power function during an alarm condition.
It is noted that while embodiments herein are discussed in the context of a power supply for a fire alarm device, the present disclosure is not so limited. A power supply in accordance with the present disclosure can be used to operate in a first mode as a voltage source and in a second mode as a current source in any suitable device where such switching is desirable.
In the example of a fire alarm device, the self-test module is used to self-test sensors of the device (e.g., optical sensors) with the power supply in the first mode. In some embodiments, the self-test module includes a heater coil. The heater coil can be coated in high temperature paraffin wax or can have a wick embedded in paraffin wax in its center. When the heater coil is switched across the power supply, a large current flows in the coil. This current can be either a direct current (DC) or pulsed alternating current (AC). In either case, the coil can be heated to a sufficiently high temperature such that a portion of the wax vaporizes and forms an aerosol.
In some embodiments, a fan is switched across the power supply using a pulse width modulation (PWM) control to regulate the fan speed. The timing of the coil heating cycle and fan speed cycle can enable the aerosol to move into an optical scatter smoke chamber for detection and to be cleared from the device via the smoke inlet paths, thereby proving smoke entry.
In the above self-test example, a sequence of testing occurs on a loop, so that only a limited number of devices of the fire alarm system will utilize heating current at the same time. Accordingly, the maximum loop current available will not be exceeded. A conventional negative feedback control loop can be configured by a controller (e.g., a microcontroller unit (MCU)) to produce a stable voltage level to power the heater coil and fan during an optical self-test. A self-test sequence will stop if a fire alarm occurs, so the same power supply can be used for each function.
In accordance with the present disclosure, the visual alarm device can utilize the same power supply reconfigured as a digitally controlled current source (e.g., operating in the second mode). In some embodiments, the current source is used to charge a super-capacitor energy store. A large pulse current can be taken out of the super-capacitor energy store using a boost converter to provide a pulse current into a chain of light-emitting diodes (LEDs) periodically (e.g., every two seconds). This low frequency (e.g., 0.5 Hz) pulse current causes the voltage on the super-capacitor to fall.
In previous approaches, a conventional negative feedback control loop would now try to correct this ‘voltage error’ as fast as it can and using as much current as it can. However, this would just cause a large, low frequency, synchronized pulse current to appear on the loop wiring, cumulatively for all the visual alarm devices used. Embodiments herein instead utilize a predictive control loop. The power supply, acting as a controlled current source, charges the super-capacitor energy store back-up over the complete period (e.g., two seconds) to the correct operating point, using the minimum amount of current and filtering out (e.g., completely filtering out) the low frequency load current pulses.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof. The drawings show by way of illustration how one or more embodiments of the disclosure may be practiced.
These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice one or more embodiments of this disclosure. It is to be understood that other embodiments may be utilized and that mechanical, electrical, and/or process changes may be made without departing from the scope of the present disclosure.
As will be appreciated, elements shown in the various embodiments herein can be added, exchanged, combined, and/or eliminated so as to provide a number of additional embodiments of the present disclosure. The proportion and the relative scale of the elements provided in the figures are intended to illustrate the embodiments of the present disclosure, and should not be taken in a limiting sense.
The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 112 may reference element “12” in
As used herein, “a”, “an”, or “a number of” something can refer to one or more such things, while “a plurality of” something can refer to more than one such things. For example, “a number of devices” can refer to one or more devices, while “a plurality of devices” can refer to more than one device. Additionally, the designators “N” and “M” as used herein, particularly with respect to reference numerals in the drawings, indicate that a number of the particular feature so designated can be included with a number of embodiments of the present disclosure. This number may be the same or different between designations.
As shown in
Operations of power supply 106 and/or loop driver 105 can be controlled by control panel 104. In some embodiments, fire alarm system 100 can use combined power transmission and digital communications on a screened (e.g., shielded) two-wire loop. In some embodiments, fire alarm system 100 can use combined power transmission and digital communications on an unshielded cable.
As shown in
For instance, alarm devices 110-1, 110-2, . . . , 110-N can each include an audio notification mechanism, such as a speaker, sounder, or siren (e.g., the warning provided by the device can be and/or include an audio warning), and/or a visual notification mechanism, such as a display, light, sign, or strobe (e.g., the warning provided by the device can be and/or include a visual warning). In some embodiments, the visual notification mechanism is a strobe that includes a number of light-emitting diodes (LEDs) connected in series. However, embodiments of the present disclosure are not limited to a particular type of visual notification mechanism. In some embodiments, the audio notification mechanism is a piezoelectric sounder (e.g., a piezo-sounder) that can provide multiple alarm tones and a voice message. For instance, the audio notification mechanism can be a class-D amplifier that includes a piezoelectric transducer. However, embodiments of the present disclosure are not limited to a particular type of audio notification mechanism.
As shown in
Although not shown in
The memory can be volatile or nonvolatile memory. The memory can also be removable (e.g., portable) memory, or non-removable (e.g., internal) memory. For example, the memory can be random access memory (RAM) (e.g., dynamic random access memory (DRAM), resistive random access memory (RRAM), and/or phase change random access memory (PCRAM)), read-only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM) and/or compact-disk read-only memory (CD-ROM)), flash memory, a laser disk, a digital versatile disk (DVD) or other optical disk storage, and/or a magnetic medium such as magnetic cassettes, tapes, or disks, among other types of memory.
In addition, the circuit includes an analog to digital converter (ADC) component 222, a processor (e.g., microprocessing unit) 224, a pulse width modulation (PWM) component 226, feedback control resistors 228 and 230, and feedback input 232.
The processor 224 can receive commands and/or instructions from a control panel (e.g., the control panel 104) to switch between a first mode and a second mode of operation. The power supply, via the circuit illustrated in
the self-test component 223 is used to self-test sensors of the device (e.g., optical sensors) with the power supply in the first mode. In some embodiments, the self-test module includes a heater coil. The heater coil can be coated in high temperature paraffin wax or can have a wick embedded in paraffin wax in its center. When the heater coil is switched across the power supply, a large current flows in the coil. This current can be either a direct current (DC) or pulsed alternating current (AC). In either case, the coil can be heated to a sufficiently high temperature such that a portion of the wax vaporizes and forms an aerosol.
In some embodiments, a fan is switched across the power supply using a pulse width modulation (PWM) control to regulate the fan speed. The timing of the coil heating cycle and fan speed cycle can enable the aerosol to move into an optical scatter smoke chamber for detection and to be cleared from the device via the smoke inlet paths, thereby proving smoke entry.
In the above self-test example, a sequence of testing occurs on a loop, so that only a limited number of devices of the fire alarm system will utilize heating current at the same time. Accordingly, the maximum loop current available will not be exceeded. A conventional negative feedback control loop can be configured by a controller (e.g., a microcontroller unit (MCU)) to produce a stable voltage level to power the heater coil and fan during an optical self-test. A self-test sequence will stop if a fire alarm occurs, so the same power supply can be used for each function.
In an alarm condition, the mode can be switched from the first mode to the second mode.
As shown in
The supercapacitor can provide a large instantaneous output pulse current to the alarm component 221. The alarm component 221 can include a boost converter that can amplify (e.g., boost) the voltage provided to the alarm component
Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art will appreciate that any arrangement calculated to achieve the same techniques can be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments of the disclosure.
It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combination of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description.
The scope of the various embodiments of the disclosure includes any other applications in which the above structures and methods are used. Therefore, the scope of various embodiments of the disclosure should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.
In the foregoing Detailed Description, various features are grouped together in example embodiments illustrated in the figures for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the embodiments of the disclosure require more features than are expressly recited in each claim.
Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.
