Indoor wireless fire detection device

Abstract

This invention relates to an indoor wireless fire detection device. The device includes: K-type thermocouples, thermocouple digital converter chips, a main control unit, and a power supply module. Multiple sets of K-type thermocouples are installed in the top, middle, and bottom areas of the room. Multiple thermocouple digital converter chips are connected one-to-one with the multiple sets of K-type thermocouples, converting the voltage signals output by the K-type thermocouples into digital signals and outputting them through an SPI (Read-Only Serial Peripheral) interface. The main control unit is connected to each thermocouple digital converter chip and communicates with each chip via an SPI bus. It acquires the output signals of each thermocouple digital converter chip and determines whether to trigger an alarm based on the output signals. The main control unit also connects to WiFi and sends information to a cloud platform. The power supply module supplies power to the thermocouple digital converter chips and the main control unit. This device facilitates timely and accurate alarm information delivery to users.

Description

Technical Field

[0001] This invention relates to the field of Internet of Things (IoT) fire early warning technology, and in particular to an indoor wireless fire detection device. Background Technology

[0002] There are three main types of existing residential fire detection solutions: (1) Traditional stand-alone smoke / temperature detectors: have a single function, no network capability, and no alarm when no one is home; single-point detection, unable to sense vertical temperature gradient.

[0003] (2) Networked fire alarm system: High cost (thousands to tens of thousands of yuan), complex installation and wiring, not suitable for ordinary households.

[0004] (3) Wireless sensors for smart homes: mostly use NTC thermistors, with a narrow measurement range (<100℃), and are easily damaged under high temperature in fire; single-point deployment, lacking three-dimensional monitoring; rely on batteries or sockets, making deployment inconvenient.

[0005] In addition, industry-standard wireless thermocouple acquisition modules are all industrial single-point temperature measurement modules, lacking vertical three-dimensional layout for home use, lacking fire heat plume discrimination algorithms, and are costly and unsuitable for residential use in communities. Summary of the Invention

[0006] Based on this, an indoor wireless fire detection device is provided. This device facilitates the timely and accurate delivery of alarm information to users.

[0007] The specific plan is as follows: An indoor wireless fire detection device, comprising: Multiple sets of K-type thermocouples are used to be installed in the top, middle, and bottom areas of the room. Multiple thermocouple-to-digital converter chips are connected one-to-one with multiple sets of K-type thermocouples to convert the voltage signals output by the K-type thermocouples into digital signals, which are then output through an SPI (Read-Only Serial Peripheral) interface. The main control unit is connected to each thermocouple-to-digital converter chip and communicates with them via an SPI bus. It acquires the output signals of each thermocouple-to-digital converter chip and determines whether to trigger an alarm based on these signals. The main control unit also connects to WiFi and sends information to the cloud platform. A power supply module is used to supply power to the thermocouple digital converter chip and the main control unit.

[0008] In one embodiment, the thermocouple-to-digital converter chip is a MAX6675 chip: each MAX6675 chip is connected to a group of K-type thermocouples.

[0009] In one embodiment, the main control unit includes an ESP8266 WiFi microcontroller module, which communicates with each MAX6675 chip via an SPI bus.

[0010] In one embodiment, the power supply module draws power from the router's network cable or from the router's USB port.

[0011] In one embodiment, both the MAX6675 chip and the ESP8266 WiFi microcontroller module are powered by a single 3.3V power supply. A 0.1μF ceramic decoupling capacitor is connected in parallel at the power input terminals of the MAX6675 chip and the ESP8266 WiFi microcontroller module to suppress power ripple. A self-resetting fuse and a reverse connection protection diode are connected in series in the power circuit.

[0012] In one embodiment, the information sent by the main control unit to the cloud platform includes alarm information, temperature information, and temperature difference information.

[0013] In one embodiment, after receiving an alarm message, the cloud platform pushes a pop-up window to a mobile APP or mini-program, sends a text message, or triggers a voice call.

[0014] In one embodiment, Single-point over-temperature detection: If the detection value of any K-type thermocouple exceeds the first preset threshold, a high-temperature event is generated, and the main control unit sends the high-temperature event to the cloud platform. Vertical temperature difference judgment: Calculate ΔT = T_top - T_bottom, where T_top is the detection value of the K-type thermocouple in the top area of ​​the room and T_bottom is the detection value of the K-type thermocouple in the bottom area of ​​the room. If ΔT > 10℃ and T_top > 55℃, the main control unit sends an alarm message to the cloud platform.

[0015] In one embodiment, Static threshold judgment condition: If the detection value of any K-type thermocouple is greater than or equal to the second preset threshold, the main control unit sends a level one warning message to the cloud platform. Vertical temperature difference judgment condition: Calculate ΔT = T_top - T_bottom, where T_top is the detection value of the K-type thermocouple in the top area of ​​the room, and T_bottom is the detection value of the K-type thermocouple in the bottom area of ​​the room. If ΔT is greater than or equal to the third preset threshold, the control unit sends local abnormal heat source information to the cloud platform. Temperature rise rate judgment condition: If the increase rate of the detection value of any K-type thermocouple is greater than or equal to the set rate, the control unit sends an abnormal rapid temperature rise information to the cloud platform. Multi-cycle verification: If the detection values ​​collected consecutively all meet the above three judgment conditions, the control unit sends an alarm message to the cloud platform.

[0016] In one embodiment, the main control unit detects whether the K-type thermocouple is open-circuited or whether the communication is abnormal based on the acquired information, and reports the fault information to the cloud platform.

[0017] The beneficial effects of this application are as follows: The problems with existing technologies are: the above solutions lack three-dimensional detection of the rising characteristics of hot airflow in fires; there is a contradiction between networking functionality and low cost; power supply is inconvenient; and local heat sources can easily lead to false alarms.

[0018] 1. Three-dimensional monitoring with low false alarms: This application installs K-type thermocouples in the top, middle and bottom areas of the room, using a multi-point vertical arrangement. It also uses temperature difference judgment to effectively eliminate false alarms from local heat sources, and detects fires tens of seconds earlier than single-point detection methods.

[0019] 2. Wireless networking and mobile phone alarm: The device in this application uses home WiFi, which does not require a gateway, and alarm information can be received even when no one is at home.

[0020] 3. Power supply is very simple: it draws power from the router's network cable (PoE) or USB port, requiring no socket and is plug-and-play.

[0021] 4. Ultra-low cost: Suitable for large-scale household deployment in communities.

[0022] 5. High temperature resistance and calibration-free: The K-type thermocouple can measure 700℃, and the MAX6675 chip has built-in cold junction compensation and open circuit detection functions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of an indoor wireless fire detection device according to an embodiment of this application.

[0024] Figure 2 This is a circuit diagram showing the connection of the ESP8266 WiFi microcontroller module, three MAX6675 chips, and the power supply module.

[0025] Figure 3 A flowchart of the operation of an indoor wireless fire detection device according to an embodiment of this application.

[0026] Figure 4 This application presents a schematic diagram of the arrangement of multiple sets of K-type thermocouples inside a room, wherein the circles in the diagram represent the arrangement positions inside the room. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] like Figure 1 As shown, an embodiment of this application provides an indoor wireless fire detection device, which includes: multiple sets of K-type thermocouples, multiple thermocouple digital converter chips, a main control unit, and a power supply module. The multiple sets of K-type thermocouples are used to be installed in the top, middle, and bottom areas of the room. The multiple thermocouple digital converter chips are connected one-to-one with the multiple sets of K-type thermocouples to convert the voltage signals output by the K-type thermocouples into digital signals, which are then output through an SPI (Read-Only Serial Peripheral) interface. The main control unit is connected to each thermocouple digital converter chip and communicates with each thermocouple digital converter chip via an SPI bus. It is used to acquire the output signals of each thermocouple digital converter chip and determine whether to trigger an alarm based on the output signals. The main control unit is also used to connect to WiFi and send information to a cloud platform. The power supply module is used to supply power to the thermocouple digital converter chips and the main control unit.

[0029] Specifically, three sets of K-type thermocouples can be installed in the upper part (0.3m from the ceiling), middle part (about 1.5m from the ceiling), and lower part (0.5m from the ground) of the room, respectively. This allows for the collection of multiple temperature points and the acquisition of vertical temperature gradients.

[0030] In one embodiment, the thermocouple-to-digital converter chip is a MAX6675 chip: each MAX6675 chip is connected to a group of K-type thermocouples.

[0031] Specifically, three MAX6675 chips are connected to a set of K-type thermocouples (probes). The MAX6675 chip integrates a signal amplifier, cold junction compensation circuit and 12-bit analog-to-digital converter (ADC), which can convert the weak voltage signal output by the thermocouple into a digital temperature value and output it through the SPI read-only serial peripheral interface.

[0032] In one embodiment, the main control unit includes an ESP8266 WiFi microcontroller module, which communicates with each MAX6675 chip via an SPI bus.

[0033] Specifically, an ESP8266 WiFi microcontroller module acts as the master control unit, communicating with three MAX6675 chips via the SPI bus. The SCK (serial clock line) and SO (serial data output line, corresponding to MISO on the master device side) pins are connected in parallel to all MAX6675 chips. Each MAX6675 chip has an independent CS (chip select) pin, which is pulled low by the ESP8266 WiFi microcontroller module in stages to achieve multi-channel temperature acquisition. The ESP8266 WiFi microcontroller module simultaneously handles temperature reading, fire detection algorithm execution, local data storage, and WiFi wireless upload functions.

[0034] In one embodiment, the power supply module draws power from the router's network cable or from the router's USB port.

[0035] Specifically, the primary power supply module is a PoE module (powered by the router's network cable), with the alternative being a router USB port power supply (5V → LDO → 3.3V).

[0036] In one embodiment, both the MAX6675 chip and the ESP8266 WiFi microcontroller module are powered by a single 3.3V power supply. A 0.1μF ceramic decoupling capacitor is connected in parallel at the power input terminals of the MAX6675 chip and the ESP8266 WiFi microcontroller module to suppress power ripple. A self-resetting fuse and a reverse connection protection diode are connected in series in the power circuit to improve system reliability.

[0037] In one embodiment, the information sent by the main control unit to the cloud platform includes alarm information, temperature information, and temperature difference information.

[0038] In one embodiment, after receiving an alarm message, the cloud platform pushes a pop-up window to a mobile APP or mini-program, sends a text message, or triggers a voice call.

[0039] In one embodiment, the conditions for the main control unit to determine whether an alarm has been triggered may be: Single-point over-temperature detection: If the detection value of any K-type thermocouple exceeds the first preset threshold, a high-temperature event is generated, and the main control unit sends the high-temperature event to the cloud platform. Vertical temperature difference judgment: Calculate ΔT = T_top - T_bottom, where T_top is the detection value of the K-type thermocouple in the top area of ​​the room and T_bottom is the detection value of the K-type thermocouple in the bottom area of ​​the room. If ΔT > 10℃ and T_top > 55℃, the main control unit sends an alarm message to the cloud platform.

[0040] In one embodiment, the conditions for the main control unit to determine whether an alarm has been triggered may be: Static threshold judgment condition: If the detection value of any K-type thermocouple is greater than or equal to the second preset threshold, the main control unit sends a level one warning message to the cloud platform. Vertical temperature difference judgment condition: Calculate ΔT = T_top - T_bottom, where T_top is the detection value of the K-type thermocouple in the top area of ​​the room, and T_bottom is the detection value of the K-type thermocouple in the bottom area of ​​the room. If ΔT is greater than or equal to the third preset threshold, the control unit sends local abnormal heat source information to the cloud platform. Temperature rise rate judgment condition: If the increase rate of the detection value of any K-type thermocouple is greater than or equal to the set rate, the control unit sends an abnormal rapid temperature rise information to the cloud platform. Multi-cycle verification: If the detection values ​​collected consecutively all meet the above three judgment conditions, the control unit sends an alarm message to the cloud platform.

[0041] In one embodiment, the main control unit detects whether the K-type thermocouple is open-circuited or whether the communication is abnormal based on the acquired information, and reports the fault information to the cloud platform.

[0042] It should be noted that: 1. The time-sharing acquisition control logic for multiple MAX6675 chips is as follows: The ESP8266 WiFi microcontroller module controls three CS signals via independent GPIO pins, using a time-division multiplexing approach to pull the chip select low to achieve multi-channel polling data acquisition. The specific process is as follows: Pull the CS pin of the first MAX6675 chip low to enable the chip's SPI interface; The ESP8266 WiFi microcontroller module outputs 16 clock pulses to read the 16-bit data frame output by the chip; Pulling the first CS pin high terminates the current communication and triggers the chip to start a new round of temperature conversion; Repeat the above process for the second and third MAX6675 chips in sequence to complete the acquisition of three temperature data. The single-channel acquisition interval should not be less than the conversion cycle of the MAX6675 chip (typical value 100ms) to ensure that the read data is the latest conversion result.

[0043] 2. The MAX6675 chip's data frame parsing and fault handling methods are as follows: The 16-bit data frame format read by the ESP8266 WiFi microcontroller module is as follows: D15 (0, virtual bit), D14~D3 (12-bit temperature data, resolution 0.25℃), D2 (thermocouple open circuit detection bit, 1 = probe disconnection, 0 = normal), D1 (device ID, fixed at 0), and D0 (tri-state bit, no practical meaning).

[0044] The system processes the data frames as follows: If D2=1, it is determined as "thermocouple probe open circuit fault", and fault alarm information is uploaded; If the data frame format is abnormal (e.g., virtual bits are not 0), it is determined as "SPI communication failure" and the resampling mechanism is triggered; Normal data can be converted to actual temperature using the formula: Temperature value = Data value × 0.25℃.

[0045] Furthermore, the device in this application is deployed as follows: in the living room of a residence, the router is located on the TV cabinet and has a USB port. The device casing is 6×5×3cm and is fixed to the side of the TV cabinet with 3M adhesive.

[0046] Three K-type thermocouple probe wires are laid along the wall: the top is 0.3m below the ceiling, the middle is 1.2m below the ceiling on the wall, and the bottom is 0.1m from the ground.

[0047] Connect the device to the router's USB port using a Micro USB cable for power, and the device will automatically connect to WiFi and the cloud platform.

[0048] Users can scan a QR code to bind their app and view real-time temperatures.

[0049] Furthermore, the workflow of the device in this application can be: The system reports information every 5 seconds, for example, T_top=25.3℃, T_mid=24.1℃, T_bottom=23.0℃, ΔT=2.3℃.

[0050] In the event of a fire, such as a fire originating in the electrical outlet behind a television, the temperature rises to 62.5℃ at the top, 32.0℃ in the middle, and 24.5℃ at the bottom, with a ΔT of 38.0℃. The ESP8266 WiFi microcontroller module locally determines that T_top > 55℃ and ΔT > 10℃, triggering a fire alarm and sending a notification to the cloud platform via MQTT. The cloud platform then pushes a "living room fire" notification to the user's mobile app, simultaneously sending an SMS and a voice call. The entire process takes less than 10 seconds.

[0051] The device in this application has a false alarm prevention function. For example, if an electric heater is close to the ground, with the bottom at 70°C and the top at 24°C, ΔT is a negative value. The device will only report a "bottom high temperature event" and will not trigger a fire alarm.

[0052] Furthermore, through centralized property management, all devices can be registered to the property cloud platform, and the household number can be displayed on the large screen when an alarm is triggered, allowing property management to conduct on-site verification.

[0053] It should be noted that when the device of this application cannot be close to the router, it can be powered by AA batteries. For example, the ESP8266 WiFi microcontroller module is in deep sleep and wakes up every 5 minutes. Three AA batteries can last for half a year, or it can be powered by lithium batteries.

[0054] It should be noted that the core circuit connections of the device in this application can be found in Table 1.

[0055] Table 1

[0056] The following is combined with Figure 3 The working principle of the device in this application will be explained in detail.

[0057] S100, Power-on Internet Connection: The ESP8266 WiFi microcontroller module automatically connects to the home WiFi and connects to the cloud platform (own IoT platform) via the MQTT protocol.

[0058] S200, Multi-point Acquisition: Time-division reading of three temperature points T_top, T_mid, and T_bottom, with each reading at 250ms interval.

[0059] S300, Edge Computing and Fire Detection: Single-point over-temperature judgment: A high-temperature event is generated when any point exceeds the threshold (e.g., 60℃).

[0060] Vertical temperature difference determination: Calculate ΔT = T_top - T_bottom. If ΔT > 10℃ and T_top > 55℃, it is determined to be a fire heat plume, triggering a "fire gradient alarm". This logic can distinguish between a real fire and a local heat source (such as an electric heater).

[0061] The system is based on three-channel temperature data, and can also employ a three-dimensional discrimination logic of "static threshold + vertical temperature difference + temperature rise rate". Static threshold judgment: If any temperature is greater than or equal to the set threshold (e.g., 55℃), a level 1 warning is triggered; Vertical temperature difference detection: If the temperature difference between the upper and lower paths is greater than or equal to the set threshold (10℃), the influence of the ambient temperature gradient is excluded, and the local abnormal heat source is identified; Temperature rise rate judgment: If the temperature rise per unit time (e.g., 1 minute) of a single channel is greater than or equal to the set rate (e.g., 8℃ / min), the rapid temperature rise is judged to be abnormal; Multi-cycle verification: Only when the above conditions are met for 2 to 3 consecutive data collections is it determined to be a fire hazard and an alarm is triggered, thus avoiding false alarms caused by momentary interference.

[0062] S400, Data Reporting: Under normal conditions, temperature and temperature difference are uploaded every 5 seconds; under alarm conditions, alarm information is immediately sent to the cloud platform via MQTT.

[0063] S500 and cloud platform linkage: After receiving the alarm information, the cloud platform will push pop-ups, send text messages, or trigger voice calls to the user's mobile APP or mini-program.

[0064] S600, Fault Self-Check: Detects open circuits in thermocouples or communication abnormalities and reports fault information.

[0065] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An indoor wireless fire detection device, characterized in that, include: Multiple sets of K-type thermocouples are used to be installed in the top, middle, and bottom areas of the room. Multiple thermocouple-to-digital converter chips are connected one-to-one with multiple sets of K-type thermocouples to convert the voltage signals output by the K-type thermocouples into digital signals, which are then output through an SPI (Read-Only Serial Peripheral) interface. The main control unit is connected to each thermocouple-to-digital converter chip and communicates with them via an SPI bus. It acquires the output signals of each thermocouple-to-digital converter chip and determines whether to trigger an alarm based on these signals. The main control unit also connects to WiFi and sends information to the cloud platform. A power supply module is used to supply power to the thermocouple digital converter chip and the main control unit.

2. The indoor wireless fire detection device according to claim 1, characterized in that, The thermocouple-to-digital converter chip is a MAX6675 chip: each MAX6675 chip is connected to a group of K-type thermocouples.

3. The indoor wireless fire detection device according to claim 2, characterized in that, The main control unit includes an ESP8266 WiFi microcontroller module, which communicates with each MAX6675 chip via an SPI bus.

4. The indoor wireless fire detection device according to claim 1, characterized in that, The power supply module draws power from the router's network cable or from the router's USB port.

5. The indoor wireless fire detection device according to claim 3, characterized in that, Both the MAX6675 chip and the ESP8266 WiFi microcontroller module are powered by a single 3.3V power supply. A 0.1μF ceramic decoupling capacitor is connected in parallel at the power input terminals of the MAX6675 chip and the ESP8266 WiFi microcontroller module to suppress power ripple. A self-resetting fuse and a reverse connection protection diode are connected in series in the power circuit.

6. The indoor wireless fire detection device according to claim 1, characterized in that, The information sent by the main control unit to the cloud platform includes alarm information, temperature information, and temperature difference information.

7. The indoor wireless fire detection device according to claim 6, characterized in that, After receiving the alarm information, the cloud platform will push a pop-up window to the mobile APP or mini-program, send a text message, or trigger a voice call.

8. The indoor wireless fire detection device according to claim 1, characterized in that, Single-point over-temperature detection: If the detection value of any K-type thermocouple exceeds the first preset threshold, a high-temperature event is generated, and the main control unit sends the high-temperature event to the cloud platform. Vertical temperature difference judgment: Calculate ΔT = T_top - T_bottom, where T_top is the detection value of the K-type thermocouple in the top area of ​​the room and T_bottom is the detection value of the K-type thermocouple in the bottom area of ​​the room. If ΔT > 10℃ and T_top > 55℃, the main control unit sends an alarm message to the cloud platform.

9. The indoor wireless fire detection device according to claim 1, characterized in that, Static threshold judgment condition: If the detection value of any K-type thermocouple is greater than or equal to the second preset threshold, the main control unit sends a level one warning message to the cloud platform. Vertical temperature difference judgment condition: Calculate ΔT = T_top - T_bottom, where T_top is the detection value of the K-type thermocouple in the top area of ​​the room, and T_bottom is the detection value of the K-type thermocouple in the bottom area of ​​the room. If ΔT is greater than or equal to the third preset threshold, the main control unit sends local abnormal heat source information to the cloud platform. Temperature rise rate judgment condition: If the increase rate of the detection value of any K-type thermocouple is greater than or equal to the set rate, the main control unit sends an abnormal rapid temperature rise information to the cloud platform. Multi-cycle verification: If the detection values ​​collected consecutively all meet the above three judgment conditions, the main control unit sends an alarm message to the cloud platform.

10. The indoor wireless fire detection device according to claim 1, characterized in that, The main control unit detects whether the K-type thermocouple is open or whether the communication is abnormal based on the acquired information, and reports the fault information to the cloud platform.

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